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Sample records for absorption features due

  1. DEEP SILICATE ABSORPTION FEATURES IN COMPTON-THICK ACTIVE GALACTIC NUCLEI PREDOMINANTLY ARISE DUE TO DUST IN THE HOST GALAXY

    SciTech Connect

    Goulding, A. D.; Forman, W. R.; Jones, C.; Trichas, M.; Alexander, D. M.; Mullaney, J. R.; Bauer, F. E.; Hickox, R. C.

    2012-08-10

    We explore the origin of mid-infrared (mid-IR) dust extinction in all 20 nearby (z < 0.05) bona fide Compton-thick (N{sub H} > 1.5 Multiplication-Sign 10{sup 24} cm{sup -2}) active galactic nuclei (AGNs) with hard energy (E > 10 keV) X-ray spectral measurements. We accurately measure the silicate absorption features at {lambda} {approx} 9.7 {mu}m in archival low-resolution (R {approx} 57-127) Spitzer Infrared Spectrograph spectroscopy, and show that only a minority ( Almost-Equal-To 45%) of nearby Compton-thick AGNs have strong Si-absorption features (S{sub 9.7} = ln (f{sub int}/f{sub obs}) {approx}> 0.5) which would indicate significant dust attenuation. The majority ( Almost-Equal-To 60%) are star formation dominated (AGN:SB < 0.5) at mid-IR wavelengths and lack the spectral signatures of AGN activity at optical wavelengths, most likely because the AGN emission lines are optically extinguished. Those Compton-thick AGNs hosted in low-inclination-angle galaxies exhibit a narrow range in Si-absorption (S{sub 9.7} {approx} 0-0.3), which is consistent with that predicted by clumpy-torus models. However, on the basis of the IR spectra and additional lines of evidence, we conclude that the dominant contribution to the observed mid-IR dust extinction is dust located in the host galaxy (i.e., due to disturbed morphologies, dust lanes, galaxy inclination angles) and not necessarily a compact obscuring torus surrounding the central engine.

  2. 4.6 micron absorption features due to solid phase CO and cyano group molecules toward compact infrared sources

    NASA Technical Reports Server (NTRS)

    Lacy, J. H.; Baas, F.; Allamandola, L. J.; Van De Bult, C. E. P.; Persson, S. E.; Mcgregor, P. J.; Lonsdale, C. J.; Geballe, T. R.

    1984-01-01

    Spectra obtained at a resolving power of 840, for seven protostellar sources in the region of the 4.67-micron fundamental vibrational band of CO, indicate that the deep absorption feature in W33A near 4.61 microns consists of three features which are seen in other sources, but with varying relative strength. UV-irradiation laboratory experiments with 'dirty ice' temperature cycling allow the identification of two of the features cited with solid CO and CO complexed to other molecules. Cyano group-containing molecules have a lower vapor pressure than CO, and can therefore survive in much warmer environments. The formation and location of the CO- and CN-bearing grain mantles and sources of UV irradiation in cold molecular clouds are discussed. Plausible UV light sources can produce the observed cyano group features, but only under conditions in which local heat sources do not cause evaporation of the CO molecules prior to their photoprocessing.

  3. Absorption Features in Soil Spectra Assessment.

    PubMed

    Vašát, Radim; Kodešová, Radka; Borůvka, Luboš; Jakšík, Ondřej; Klement, Aleš; Drábek, Ondřej

    2015-12-01

    From a wide range of techniques appropriate to relate spectra measurements with soil properties, partial least squares (PLS) regression and support vector machines (SVM) are most commonly used. This is due to their predictive power and the availability of software tools. Both represent exclusively statistically based approaches and, as such, benefit from multiple responses of soil material in the spectrum. However, physical-based approaches that focus only on a single spectral feature, such as simple linear regression using selected continuum-removed spectra values as a predictor variable, often provide accurate estimates. Furthermore, if this approach extends to multiple cases by taking into account three basic absorption feature parameters (area, width, and depth) of all occurring features as predictors and subjecting them to best subset selection, one can achieve even higher prediction accuracy compared with PLS regression. Here, we attempt to further extend this approach by adding two additional absorption feature parameters (left and right side area), as they can be important diagnostic markers, too. As a result, we achieved higher prediction accuracy compared with PLS regression and SVM for exchangeable soil pH, slightly higher or comparable for dithionite-citrate and ammonium oxalate extractable Fe and Mn forms, but slightly worse for oxidizable carbon content. Therefore, we suggest incorporating the multiple linear regression approach based on absorption feature parameters into existing working practices. PMID:26555184

  4. Weibel instability due to inverse bremsstrahlung absorption

    SciTech Connect

    Bendib, A.; Bendib, K.,; Bendib, A.; Bendib, K.; Sid, A.,; Bendib, K.,

    1997-06-01

    A new Weibel source due to the inverse bremsstrahlung absorption is presented. It has been shown that in homogeneous plasmas, this mechanism may drive strong collisionless Weibel modes with growth rates of order of {gamma}{approximately}10{sup 11}s{sup {minus}1} and negligible group velocities. In the laser-produced plasmas, for short laser wavelengths ({lambda}{sub L}{lt}1{mu}m) and high laser fluxes (I{gt}10{sup 14}W/cm{sup 2}), this Weibel source is most efficient as the ones due to the heat flux and the plasma expansion. The useful scaling law of the convective e-foldings, with respect to the laser and the plasma parameters, is also derived. {copyright} {ital 1997} {ital The American Physical Society}

  5. Onshore seismic amplifications due to bathymetric features

    NASA Astrophysics Data System (ADS)

    Rodríguez-Castellanos, A.; Carbajal-Romero, M.; Flores-Guzmán, N.; Olivera-Villaseñor, E.; Kryvko, A.

    2016-08-01

    We perform numerical calculations for onshore seismic amplifications, taking into consideration the effect of bathymetric features on the propagation of seismic movements. To this end, the boundary element method is applied. Boundary elements are employed to irradiate waves and, consequently, force densities can be obtained for each boundary element. From this assumption, Huygens’ principle is applied, and since the diffracted waves are built at the boundary from which they are radiated, this idea is equivalent to Somigliana’s representation theorem. The application of boundary conditions leads to a linear system being obtained (Fredholm integral equations). Several numerical models are analyzed, with the first one being used to verify the proposed formulation, and the others being used to estimate onshore seismic amplifications due to the presence of bathymetric features. The results obtained show that compressional waves (P-waves) generate onshore seismic amplifications that can vary from 1.2 to 5.2 times the amplitude of the incident wave. On the other hand, the shear waves (S-waves) can cause seismic amplifications of up to 4.0 times the incident wave. Furthermore, an important result is that in most cases the highest seismic amplifications from an offshore earthquake are located on the shoreline and not offshore, despite the seafloor configuration. Moreover, the influence of the incident angle of seismic waves on the seismic amplifications is highlighted.

  6. Empathic features of absorption and incongruence.

    PubMed

    Wickramasekera, Ian E

    2007-07-01

    A study was undertaken to examine whether empathy could be related to absorption and incongruence (repressive coping). The participants were 71 graduate students who completed measures of empathy, absorption, and incongruence (repressive coping). The results confirmed a previous finding that empathy appears positively related to absorption (r = .42, p < .001). The results also suggest that affective components of empathy are inversely related to repressive coping (r = -.29, p < .05) while cognitive components are positively related to the social desirability aspects of incongruence (r = .31, p < .01). The findings are collectively discussed in terms of the Empathic Involvement Hypothesis of Hypnosis (Wickramasekera II, 2001), the Four-factor theory of Repressive Coping (Eysenck, 1997), Incongruence (Rogers, 1957), and the High Risk Model of Threat Perception (I. E. Wickramasekera I, 1998). PMID:17685245

  7. Absorption Features in Spectra of Magnetized Neutron Stars

    SciTech Connect

    Suleimanov, V.; Hambaryan, V.; Neuhaeuser, R.; Potekhin, A. Y.; Pavlov, G. G.; Adelsberg, M. van; Werner, K.

    2011-09-21

    The X-ray spectra of some magnetized isolated neutron stars (NSs) show absorption features with equivalent widths (EWs) of 50-200 eV, whose nature is not yet well known.To explain the prominent absorption features in the soft X-ray spectra of the highly magnetized (B{approx}10{sup 14} G) X-ray dim isolated NSs (XDINSs), we theoretically investigate different NS local surface models, including naked condensed iron surfaces and partially ionized hydrogen model atmospheres, with semi-infinite and thin atmospheres above the condensed surface. We also developed a code for computing light curves and integral emergent spectra of magnetized neutron stars with various temperature and magnetic field distributions over the NS surface. We compare the general properties of the computed and observed light curves and integral spectra for XDINS RBS 1223 and conclude that the observations can be explained by a thin hydrogen atmosphere above the condensed iron surface, while the presence of a strong toroidal magnetic field component on the XDINS surface is unlikely.We suggest that the harmonically spaced absorption features in the soft X-ray spectrum of the central compact object (CCO) 1E 1207.4-5209 (hereafter 1E 1207) correspond to peaks in the energy dependence of the free-free opacity in a quantizing magnetic field, known as quantum oscillations. To explore observable properties of these quantum oscillations, we calculate models of hydrogen NS atmospheres with B{approx}10{sup 10}-10{sup 11} G(i.e., electron cyclotron energy E{sub c,e}{approx}0.1-1 keV) and T{sub eff} = 1-3 MK. Such conditions are thought to be typical for 1E 1207. We show that observable features at the electron cyclotron harmonics with EWs {approx_equal}100-200 eV can arise due to these quantum oscillations.

  8. An analytic formula for heating due to ozone absorption

    NASA Technical Reports Server (NTRS)

    Lindzen, R. S.; Will, D. I.

    1972-01-01

    An attempt was made to devise a simple expression or formula to describe radiative heating in the atmosphere by ozone absorption. Such absorption occurs in the Hartley, Huggins, and Chappuis bands and is only slightly temperature and pressure dependent.

  9. The Extragalactic Background Light Absorption Feature in the Blazar Component of the Extragalactic Gamma-ray Background

    NASA Astrophysics Data System (ADS)

    Venters, Tonia M.; Pavlidou, Vasiliki; Reyes, Luis C.

    2009-10-01

    High-energy photons from cosmological emitters suffer attenuation due to pair production interactions with the extragalactic background light (EBL). The collective emission of any high-energy emitting cosmological population will exhibit an absorption feature at the highest energies. We calculate this absorption feature in the collective emission of blazars for various models of the blazar gamma-ray luminosity function (GLF) and the EBL. We find that models of the blazar GLF that predict higher relative contributions of high-redshift blazars to the blazar collective spectrum result in emission that is more susceptible to attenuation by the EBL, and hence result in more prominent absorption features, allowing for better differentiation amongst EBL models. We thus demonstrate that observations of such an absorption feature will contain information regarding both the blazar GLF and the EBL, and we discuss tests for EBL models and the blazar GLF that will become possible with upcoming Fermi observations.

  10. Absorption features in the 3 micron spectra of highly obscured objects

    NASA Technical Reports Server (NTRS)

    Smith, Robert G.; Sellgren, Kris; Tokunaga, Alan T.

    1989-01-01

    Using the IRTF cooled-grating spectrometer moderate resolution 2.4 to 3.8 micron spectra of a selection of IR protostars and one object located behind the Taurus dark cloud were obtained. Two examples of the spectra are presented. It is clear that the absorption near 3.07 micron is dominated by H2O ice and a comparison between the spectra and a simple H2O ice model allows a temperature estimate for the hottest ice-coated grains in these sources. Higher resolution observations showed no indication of the absorption due to the N-H stretching vibration of NH3 near 2.963 micron. The most plausible explanation for the 3.3 and 3.45 micron features appears to be absorption by the mixture of hydrocarbons, although they cannot be identified with features already attributed to hydrocarbons in the ISM, reflection nebulae and Comets. However these features appear the same for all sources in the sample, including Elias 16, thus implying a very similar mixture of molecules in each source.

  11. Detection of Variable Gaseous Absorption Features in the Debris Disks Around Young A-type Stars

    NASA Astrophysics Data System (ADS)

    Montgomery, Sharon L.; Welsh, Barry Y.

    2012-10-01

    We present medium resolution (R = 60,000) absorption measurements of the interstellar Ca II K line observed towards five nearby A-type stars (49 Ceti, 5 Vul, ι Cyg, 2 And, and HD 223884) suspected of possessing circumstellar gas debris disks. The stars were observed on a nightly basis during a six night observing run on the 2.1-meter Otto Struve telescope at the McDonald Observatory, Texas. We have detected nightly changes in the absorption strength of the Ca II K line observed near the stellar radial velocity in three of the stars (49 Ceti, i Cyg and HD 223884). Such changes in absorption suggest the presence of a circumstellar (atomic) gas disk around these stars. In addition to the absorption changes in the main Ca II K line profile, we have also observed weak transient absorption features that randomly appear at redshifted velocities in the spectra of 49 Ceti, 5 Vul, and 2 And. These absorption features are most probably associated with the presence of falling evaporated bodies (exo-comets) that liberate evaporating gas on their approach to the central star. This now brings the total number of systems in which exocomet activity has been observed at Ca II or Na I wavelengths on a nightly basis to seven (β Pic, HR 10, HD 85905, β Car, 49 Ceti, 5 Vul, and 2 And), with 2 And exhibiting weaker and less frequent changes. All of the disk systems presently known to exhibit either type of short-term variability in Ca II K line absorption are rapidly rotating A-type stars (V sin i > 120 km s-1). Most exhibit mid-IR excesses, and many of them are very young (< 20 Myr), thus supporting the argument that many of them are transitional objects between Herbig Ae and "Vega-like" A-type stars with more tenuous circumstellar disks. No mid-IR excess (due to the presence of a dust disk) has yet been detected around either 2 And or HD 223884, both of which have been classified as λ Boötis-type stars. This may indicate that the observed changes in gas absorption for these two

  12. On the nature of absorption features toward nearby stars

    NASA Astrophysics Data System (ADS)

    Kohl, S.; Czesla, S.; Schmitt, J. H. M. M.

    2016-06-01

    Context. Diffuse interstellar absorption bands (DIBs) of largely unknown chemical origin are regularly observed primarily in distant early-type stars. More recently, detections in nearby late-type stars have also been claimed. These stars' spectra are dominated by stellar absorption lines. Specifically, strong interstellar atomic and DIB absorption has been reported in τ Boo. Aims: We test these claims by studying the strength of interstellar absorption in high-resolution TIGRE spectra of the nearby stars τ Boo, HD 33608, and α CrB. Methods: We focus our analysis on a strong DIB located at 5780.61 Å and on the absorption of interstellar Na. First, we carry out a differential analysis by comparing the spectra of the highly similar F-stars, τ Boo and HD 33608, whose light, however, samples different lines of sight. To obtain absolute values for the DIB absorption, we compare the observed spectra of τ Boo, HD 33608, and α CrB to PHOENIX models and carry out basic spectral modeling based on Voigt line profiles. Results: The intercomparison between τ Boo and HD 33608 reveals that the difference in the line depth is 6.85 ± 1.48 mÅ at the DIB location which is, however, unlikely to be caused by DIB absorption. The comparison between PHOENIX models and observed spectra yields an upper limit of 34.0 ± 0.3 mÅ for any additional interstellar absorption in τ Boo; similar results are obtained for HD 33608 and α CrB. For all objects we derive unrealistically large values for the radial velocity of any presumed interstellar clouds. In τ Boo we find Na D absorption with an equivalent width of 0.65 ± 0.07 mÅ and 2.3 ± 0.1 mÅ in the D2 and D1 lines. For the other Na, absorption of the same magnitude could only be detected in the D2 line. Our comparisons between model and data show that the interstellar absorption toward τ Boo is not abnormally high. Conclusions: We find no significant DIB absorption in any of our target stars. Any differences between modeled and

  13. Discovery of a second narrow absorption feature in the near-infrared spectrum of Io

    NASA Technical Reports Server (NTRS)

    Lester, D. F.; Trafton, L. M.; Ramseyer, T. F.; Gaffney, N. I.

    1992-01-01

    A high resolution survey of the near-IR reflectance spectrum of Io has shown a sharp absorption feature centered at 5045 +/- 1/cm; this feature is not present in laboratory spectra of dilute CO2 in a matrix. Since the spectrum of cold H2S ice crystals exhibits structure near this wavelength, it is suggested that either (1) the difference in width between this feature and that of the much broader Ionian H2S ice may be due to the presence of different phases of ice at different temperatures, so that these are emphasized in the different spectral regions, or (2) H2S is trapped in an SO2 matrix.

  14. Mg I absorption features in the solar spectrum near 9 and 12 microns

    NASA Technical Reports Server (NTRS)

    Glenar, David A.; Reuter, Dennis C.; Deming, Drake; Chang, Edward S.

    1988-01-01

    High-resolution FTS observations from the Kitt Peak National Solar Observatory and the Spacelab 3 ATMOS experiment have revealed additional infrared transitions due to Mg I in the spectra of both quiet sun and sunspot penumbra. In contrast to previous observations, these transitions are seen in absorption, not emission. Absorption intensities range from 1 to 7 percent of the continuum in the quiet sun. In the penumbra, the same features appear to show Zeeman splitting. Modeling of the line profiles in the photospheric spectrum shows evidence for a factor of three overabundance in the n = 5 or more levels of Mg I in the upper photosphere, but with no deviations from a Planck source function. It is concluded that whatever the process that produces the emission (including the Lemke and Holweger mechanism), it must occur well above the tau(5000) = 0.01 level.

  15. Iron K Features in the Quasar E 1821+643: Evidence for Gravitationally Redshifted Absorption?

    NASA Technical Reports Server (NTRS)

    Yaqoob, Tahir; Serlemitsos, Peter

    2005-01-01

    We report a Chandra high-energy grating detection of a narrow, redshifted absorption line superimposed on the red wing of a broad Fe K line in the z = 0.297 quasar E 1821+643. The absorption line is detected at a confidence level, estimated by two different methods, in the range approx. 2 - 3 sigma. Although the detection significance is not high enough to exclude a non-astrophysical origin, accounting for the absorption feature when modeling the X-ray spectrum implies that the Fe-K emission line is broad, and consistent with an origin in a relativistic accretion disk. Ignoring the apparent absorption feature leads to the conclusion that the Fe-K emission line is narrower, and also affects the inferred peak energy of the line (and hence the inferred ionization state of Fe). If the absorption line (at approx. 6.2 keV in the quasar frame) is real, we argue that it could be due to gravitationally redshifted Fe XXV or Fe XXVI resonance absorption within approx. 10 - 20 gravitational radii of the putative central black hole. The absorption line is not detected in earlier ASCA and Chandra low-energy grating observations, but the absorption line is not unequivocally ruled out by these data. The Chandra high-energy grating Fe-K emission line is consistent with an origin predominantly in Fe I-XVII or so. In an ASCA observation eight years earlier, the Fe-K line peaked at approx. 6.6 keV, closer to the energies of He-like Fe triplet lines. Further, in a Chandra low-energy grating observation the Fe-K line profile was double-peaked, one peak corresponding to Fe I-XVII or so, the other peak to Fe XXVI Ly alpha. Such a wide range in ionization state of Fe is not ruled out by the HEG and ASCA data either, and is suggestive of a complex structure for the line-emitter.

  16. Phase-dependent absorption features in X-ray spectra of XDINSs

    NASA Astrophysics Data System (ADS)

    Borghese, A.; Rea, N.

    2016-06-01

    A detailed pulse phase spectroscopy using all the available XMM-Newton observations of X-ray dim isolated neutron stars (XDINSs) have revealed the presence of narrow and strongly phase-dependent absorption X-ray features. The first discovered was in the X-ray spectrum of the nearby XDINS RX J0720.4-3125. The line seems to be stable in time over a timespan of 12 years and is present in 20% of the pulsar rotation. Because of its narrow width and its strong dependency on the rotational phase, the spectral line is probably due to proton cyclotron absorption in a ˜10^{14} G confined magnetic structure (with a field strength about 7 times the dipolar field of this pulsar). Performing the same analysis to all archival XDINS data, a new possible candidate was found in the X-ray spectrum of RX J1308.6+2127. This absorption feature shows the same phase dependency and energy as the first one, revealing the presence of a high-B structure close to the stellar surface. This result supports the proposed scenario of XDINSs being aged magnetars, having still a strong non-dipolar crustal B-field component.

  17. Empathic Features and Absorption in Fantasy Role-Playing.

    PubMed

    Rivers, Anissa; Wickramasekera, Ian E; Pekala, Ronald J; Rivers, Jennifer A

    2016-01-01

    This study examined the levels of empathy and absorption of individuals who regularly play fantasy and science fiction role-playing games. A hypothesis was developed that higher levels of empathy would be found in individuals who fantasy role-play based upon previous research in hypnosis such as J. R. Hilgard's (1970) imaginative involvement hypothesis, research into the "fantasy prone" personality type (Wilson & Barber, 1981), and the empathic involvement hypothesis (Wickramasekera II & Szlyk, 2003). The participants in the current study were 127 fantasy role-players who volunteered and completed the Davis Interpersonal Reactivity Index (empathy) and the Tellegen Absorption Scale (absorption). The results demonstrated that those who play fantasy role-playing games scored significantly higher than the comparison group on the IRI scale of empathy, confirming the hypothesis that fantasy role-players report experiencing higher levels of empathic involvement with others. Correlational analysis between the measures demonstrated a significant positive correlation between empathy and absorption (r = .43, p < .001). These results collectively suggest that fantasy role-players have a uniquely empathically-imaginative style. The results also confirm and extend previous findings on the relationship between empathy and absorption as predicted by the Empathic Involvement Hypothesis (Wickramasekera II & Szlyk, 2003). PMID:26675155

  18. Revealing spectral features in two-photon absorption spectrum of Hoechst 33342: a combined experimental and quantum-chemical study.

    PubMed

    Olesiak-Banska, Joanna; Matczyszyn, Katarzyna; Zaleśny, Robert; Murugan, N Arul; Kongsted, Jacob; Ågren, Hans; Bartkowiak, Wojciech; Samoc, Marek

    2013-10-10

    We present the results of wide spectral range Z-scan measurements of the two-photon absorption (2PA) spectrum of the Hoechst 33342 dye. The strongest 2PA of the dye in aqueous solution is found at 575 nm, and the associated two-photon absorption cross section is 245 GM. A weak but clearly visible 2PA band at ∼850 nm is also observed, a feature that could not be anticipated from the one-photon absorption spectrum. On the basis of the results of hybrid quantum mechanics/molecular mechanics calculations, we put forward a notion that the long-wavelength feature observed in the two-photon absorption spectrum of Hoechst 33342 is due to the formation of dye aggregates. PMID:24016295

  19. Modelling of the X-ray broad absorption features in Narrow-Line Seyfert 1s

    NASA Astrophysics Data System (ADS)

    Porquet, Delphine; Mouchet, Martine; Dumont Anne-Marie

    2000-09-01

    We investigate the origin of the broad absorption features detected near 1-1.4 keV in several Narrow-Line Seyfert 1 galaxies, by modelling the absorbing medium with various physical parameters, using the ionization code PEGAS. The observed properties of the X-ray absorption features can be reproduced by taking into account the peculiar soft X-ray excess which is well fitted by a blackbody plus an underlying power law. We equally stress that the emission coming from the absorbing medium (related to the covering factor) has a strong influence on the resulting X-ray spectrum, in particular on the apparent position and depth of the absorption features. A non-solar iron abundance may be required to explain the observed deep absorption. We also investigate the influence of an additional collisional ionization process ("hybrid case") on the predicted absorption features.

  20. Ultrafast transient absorption revisited: Phase-flips, spectral fingers, and other dynamical features.

    PubMed

    Cina, Jeffrey A; Kovac, Philip A; Jumper, Chanelle C; Dean, Jacob C; Scholes, Gregory D

    2016-05-01

    We rebuild the theory of ultrafast transient-absorption/transmission spectroscopy starting from the optical response of an individual molecule to incident femtosecond pump and probe pulses. The resulting description makes use of pulse propagators and free molecular evolution operators to arrive at compact expressions for the several contributions to a transient-absorption signal. In this alternative description, which is physically equivalent to the conventional response-function formalism, these signal contributions are conveniently expressed as quantum mechanical overlaps between nuclear wave packets that have undergone different sequences of pulse-driven optical transitions and time-evolution on different electronic potential-energy surfaces. Using this setup in application to a simple, multimode model of the light-harvesting chromophores of PC577, we develop wave-packet pictures of certain generic features of ultrafast transient-absorption signals related to the probed-frequency dependence of vibrational quantum beats. These include a Stokes-shifting node at the time-evolving peak emission frequency, antiphasing between vibrational oscillations on opposite sides (i.e., to the red or blue) of this node, and spectral fingering due to vibrational overtones and combinations. Our calculations make a vibrationally abrupt approximation for the incident pump and probe pulses, but properly account for temporal pulse overlap and signal turn-on, rather than neglecting pulse overlap or assuming delta-function excitations, as are sometimes done. PMID:27155654

  1. Ultrafast transient absorption revisited: Phase-flips, spectral fingers, and other dynamical features

    NASA Astrophysics Data System (ADS)

    Cina, Jeffrey A.; Kovac, Philip A.; Jumper, Chanelle C.; Dean, Jacob C.; Scholes, Gregory D.

    2016-05-01

    We rebuild the theory of ultrafast transient-absorption/transmission spectroscopy starting from the optical response of an individual molecule to incident femtosecond pump and probe pulses. The resulting description makes use of pulse propagators and free molecular evolution operators to arrive at compact expressions for the several contributions to a transient-absorption signal. In this alternative description, which is physically equivalent to the conventional response-function formalism, these signal contributions are conveniently expressed as quantum mechanical overlaps between nuclear wave packets that have undergone different sequences of pulse-driven optical transitions and time-evolution on different electronic potential-energy surfaces. Using this setup in application to a simple, multimode model of the light-harvesting chromophores of PC577, we develop wave-packet pictures of certain generic features of ultrafast transient-absorption signals related to the probed-frequency dependence of vibrational quantum beats. These include a Stokes-shifting node at the time-evolving peak emission frequency, antiphasing between vibrational oscillations on opposite sides (i.e., to the red or blue) of this node, and spectral fingering due to vibrational overtones and combinations. Our calculations make a vibrationally abrupt approximation for the incident pump and probe pulses, but properly account for temporal pulse overlap and signal turn-on, rather than neglecting pulse overlap or assuming delta-function excitations, as are sometimes done.

  2. Relating water absorption features to soil moisture characteristics

    NASA Astrophysics Data System (ADS)

    Tian, Jia; Philpot, William D.

    2015-09-01

    The spectral reflectance of a sample of quartz sand was monitored as the sample progressed from air-dry to fully saturated, and then back to air-dry. Wetting was accomplished by spraying small amounts of water on the surface of the sample, and collecting spectra whenever change occurred. Drying was passive, driven by evaporation from the sand surface, with spectra collected every 5 minutes until the sample was air dry. Water content was determined by monitoring the weight of the sample through both wetting and drying. There was a pronounced difference in the pattern of change in reflectance during wetting and drying, with the differences being apparent both in spectral details (i.e., the depth of absorption bands) and in the magnitude of the reflectance for a particular water content. The differences are attributable to the disposition of water in the sample. During wetting, water initially occurred only on the surface, primarily as water adsorbed onto sand particles. With increased wetting the water infiltrated deeper into the sample, gradually covering all particles and filling the pore spaces. During drying, water and air were distributed throughout the sample for most of the drying period. The differences in water distribution are assumed to be the cause of the differences in reflectance and to the differences in the depths of four strong water absorption bands.

  3. Ly(alpha) emission and absorption features in the spectra of galaxies

    NASA Technical Reports Server (NTRS)

    Chen, W. L.; Neufeld, David A.

    1994-01-01

    The combined effects of interstellar dust absorption and of scattering by hydrogen atoms may give rise to a Ly(alpha) spectral feature of negative equivalent width, as has been observed in several star-forming galaxies. By considering the transfer of Ly(alpha) line radiation and of neighboring stellar continuum radiation within a dusty galaxy, we find that dust absorption has three effects: (1) it reduces the apparent ultraviolet continuum luminosity at all wavelengths; (2) it preferentially decreases the apparent Ly(alpha) line luminosity from H II regions; and (3) it creates an 'attenuation feature' in the continuum spectrum -- centered at the Ly(alpha) rest frequency -- which occurs because the attenuation of the stellar continuum radiation increases as the Ly(alpha) rest frequency is approached, due to the effects of scattering by hydrogen atoms. For plausible values of the galactic dust content and of the disk thickness, these effects can lead to a negative net Ly(alpha) equivalent width, even for galaxies in which the unattenuated spectrum would show a strong Ly(alpha) emission line.

  4. Primordial features due to a step in the inflaton potential

    SciTech Connect

    Hazra, Dhiraj Kumar; Sriramkumar, L.; Aich, Moumita; Souradeep, Tarun; Jain, Rajeev Kumar E-mail: moumita@iucaa.ernet.in E-mail: sriram@hri.res.in

    2010-10-01

    Certain oscillatory features in the primordial scalar power spectrum are known to provide a better fit to the outliers in the cosmic microwave background data near the multipole moments of l = 22 and 40. These features are usually generated by introducing a step in the popular, quadratic potential describing the canonical scalar field. Such a model will be ruled out, if the tensors remain undetected at a level corresponding to a tensor-to-scalar ratio of, say, r ≅ 0.1. In this work, in addition to the popular quadratic potential, we investigate the effects of the step in a small field model and a tachyon model. With possible applications to future datasets (such as PLANCK) in mind, we evaluate the tensor power spectrum exactly, and include its contribution in our analysis. We compare the models with the WMAP (five as well as seven-year), the QUaD and the ACBAR data. As expected, a step at a particular location and of a suitable magnitude and width is found to improve the fit to the outliers (near l = 22 and 40) in all these cases. We point out that, if the tensors prove to be small (say, r∼<0.01), the quadratic potential and the tachyon model will cease to be viable, and more attention will need to be paid to examples such as the small field models.

  5. Spectral calibration of hyperspectral imagery using atmospheric absorption features.

    PubMed

    Guanter, Luis; Richter, Rudolf; Moreno, José

    2006-04-01

    One of the initial steps in the preprocessing of remote sensing data is the atmospheric correction of the at-sensor radiance images, i.e., radiances recorded at the sensor aperture. Apart from the accuracy in the estimation of the concentrations of the main atmospheric species, the retrieved surface reflectance is also influenced by the spectral calibration of the sensor, especially in those wavelengths mostly affected by gaseous absorptions. In particular, errors in the surface reflectance appear when a systematic shift in the nominal channel positions occurs. A method to assess the spectral calibration of hyperspectral imaging spectrometers from the acquired imagery is presented in this paper. The fundamental basis of the method is the calculation of the value of the spectral shift that minimizes the error in the estimates of surface reflectance. This is performed by an optimization procedure that minimizes the deviation between a surface reflectance spectrum and a smoothed one resulting from the application of a low-pass filter. A sensitivity analysis was performed using synthetic data generated with the MODTRAN4 radiative transfer code for several values of the spectral shift and the water vapor column content. The error detected in the retrieval is less than +/- 0.2 nm for spectral shifts smaller than 2 nm, and less than +/- 1.0 nm for extreme spectral shifts of 5 nm. A low sensitivity to uncertainties in the estimation of water vapor content was found, which reinforces the robustness of the algorithm. The method was successfully applied to data acquired by different hyperspectral sensors. PMID:16608005

  6. Plant phenolics and absorption features in vegetation reflectance spectra near 1.66 μm

    NASA Astrophysics Data System (ADS)

    Kokaly, Raymond F.; Skidmore, Andrew K.

    2015-12-01

    Past laboratory and field studies have quantified phenolic substances in vegetative matter from reflectance measurements for understanding plant response to herbivores and insect predation. Past remote sensing studies on phenolics have evaluated crop quality and vegetation patterns caused by bedrock geology and associated variations in soil geochemistry. We examined spectra of pure phenolic compounds, common plant biochemical constituents, dry leaves, fresh leaves, and plant canopies for direct evidence of absorption features attributable to plant phenolics. Using spectral feature analysis with continuum removal, we observed that a narrow feature at 1.66 μm is persistent in spectra of manzanita, sumac, red maple, sugar maple, tea, and other species. This feature was consistent with absorption caused by aromatic Csbnd H bonds in the chemical structure of phenolic compounds and non-hydroxylated aromatics. Because of overlapping absorption by water, the feature was weaker in fresh leaf and canopy spectra compared to dry leaf measurements. Simple linear regressions of feature depth and feature area with polyphenol concentration in tea resulted in high correlations and low errors (% phenol by dry weight) at the dry leaf (r2 = 0.95, RMSE = 1.0%, n = 56), fresh leaf (r2 = 0.79, RMSE = 2.1%, n = 56), and canopy (r2 = 0.78, RMSE = 1.0%, n = 13) levels of measurement. Spectra of leaves, needles, and canopies of big sagebrush and evergreens exhibited a weak absorption feature centered near 1.63 μm, short ward of the phenolic compounds, possibly consistent with terpenes. This study demonstrates that subtle variation in vegetation spectra in the shortwave infrared can directly indicate biochemical constituents and be used to quantify them. Phenolics are of lesser abundance compared to the major plant constituents but, nonetheless, have important plant functions and ecological significance. Additional research is needed to advance our understanding of the spectral influences

  7. Absorption of intense microwaves and ion acoustic turbulence due to heat transport

    SciTech Connect

    De Groot, J.S.; Liu, J.M.; Matte, J.P.

    1994-02-04

    Measurements and calculations of the inverse bremsstrahlung absorption of intense microwaves are presented. The isotropic component of the electron distribution becomes flat-topped in agreement with detailed Fokker-Planck calculations. The plasma heating is reduced due to the flat-topped distributions in agreement with calculations. The calculations show that the heat flux at high microwave powers is very large, q{sub max} {approx} 0.3 n{sub e}v{sub e}T{sub e}. A new particle model to, calculate the heat transport inhibition due to ion acoustic turbulence in ICF plasmas is also presented. One-dimensional PIC calculations of ion acoustic turbulence excited due to heat transport are presented. The 2-D PIC code is presently being used to perform calculations of heat flux inhibition due to ion acoustic turbulence.

  8. Enhancement of microbial motility due to speed-dependent nutrient absorption.

    PubMed

    Di Salvo, Mario E; Condat, C A

    2014-02-01

    Marine microorganisms often reach high swimming speeds, either to take advantage of evanescent nutrient patches or to beat Brownian forces. Since this implies that a sizable part of their energetic budget must be allocated to motion, it is reasonable to assume that some fast-swimming microorganisms may increase their nutrient intake by increasing their speed v. We formulate a model to investigate this hypothesis and its consequences, finding the steady-state solutions and analyzing their stability. Surprisingly, we find that even modest increases in nutrient absorption may lead to a significant increase of the microbial speed. In fact, evaluations obtained using realistic parameter values for bacteria indicate that the speed increase due to the enhanced nutrient absorption may be quite large. PMID:24451235

  9. Behavior of Propagation and Heating Due to Absorption of Ultrasound in Medium

    NASA Astrophysics Data System (ADS)

    Yamaya, Chiaki; Inoue, Hiroshi

    2006-05-01

    Recently, ultrasound waves have been put to practical use not only in diagnostic equipment but also in thermotherapy that uses the effect of ultrasound waves in a living body. The analysis of temperature rise due to the absorption of ultrasound in a soft tissue medium is an important analyzing object for the clarification of the effect of ultrasound waves in biological tissues and the estimation of medium constants. Three-dimensional simulations by the finite-difference time-domain (FDTD) method which used the equations that considers the absorption attenuation based on acoustic basic equations (ABEs) and the Westervelt equation have been performed. The consistency between the ABEs and the Westervelt equation is confirmed. The results of temperature measurement that uses glycerin as the absorbing medium of ultrasound are compared with those of FDTD simulation. The temperature distribution obtained by FDTD simulation almost corresponds to that obtained by experiment.

  10. Selective spatial damping of propagating kink waves due to resonant absorption

    NASA Astrophysics Data System (ADS)

    Terradas, J.; Goossens, M.; Verth, G.

    2010-12-01

    Context. There is observational evidence of propagating kink waves driven by photospheric motions. These disturbances, interpreted as kink magnetohydrodynamic (MHD) waves are attenuated as they propagate upwards in the solar corona. Aims: We show that resonant absorption provides a simple explanation to the spatial damping of these waves. Methods: Kink MHD waves are studied using a cylindrical model of solar magnetic flux tubes, which includes a non-uniform layer at the tube boundary. Assuming that the frequency is real and the longitudinal wavenumber complex, the damping length and damping per wavelength produced by resonant absorption are analytically calculated in the thin tube (TT) approximation, valid for coronal waves. This assumption is relaxed in the case of chromospheric tube waves and filament thread waves. Results: The damping length of propagating kink waves due to resonant absorption is a monotonically decreasing function of frequency. For kink waves with low frequencies, the damping length is exactly inversely proportional to frequency, and we denote this as the TGV relation. When moving to high frequencies, the TGV relation continues to be an exceptionally good approximation of the actual dependency of the damping length on frequency. This dependency means that resonant absorption is selective as it favours low-frequency waves and can efficiently remove high-frequency waves from a broad band spectrum of kink waves. The efficiency of the damping due to resonant absorption depends on the properties of the equilibrium model, in particular on the width of the non-uniform layer and the steepness of the variation in the local Alfvén speed. Conclusions: Resonant absorption is an effective mechanism for the spatial damping of propagating kink waves. It is selective because the damping length is inversely proportional to frequency so that the damping becomes more severe with increasing frequency. This means that radial inhomogeneity can cause solar

  11. Short term X-ray spectral variability of the strong iron-k absorption feature in PDS 456

    NASA Astrophysics Data System (ADS)

    Matzeu, G.; Reeves, J.; Gofford, J.; Nardini, E.; Costa, M.; Braito, V.; O'Brien, P.; Ward, M.; Turner, J.; Miller, L.

    2014-07-01

    We present a recent 500 ks Suzaku and a simultaneous 500 ks XMM-Newton & NuSTAR observations, carried out in 2013, of the nearby (z=0.184) luminous (L_{bol}˜10^{47} erg s^{-1}) quasar PDS 456. Short term X-ray spectral variability, including the presence of a strong and rapidly variable iron-K absorption feature, is observed and subsequently investigated. Here, our attention is focused on the physical interpretation of the short term variability where two models are adopted in the spectral analysis (partial covering vs coronal changes), leading to two valid interpretations. In the partial covering scenario, rapidly varying absorption is due to inhomogeneous dense material and such short timescale changes also entail that that the absorption is due to gas located in the vicinity of the black hole possibly shielding part of the outflow. In the second scenario, the complex spectral variability is due to variations in the intrinsic continuum observed as changes in the soft X-ray spectrum leading subsequent changes in the hard X-ray power-law, possibly induced by Comptonisation in the disc corona. Furthermore it was possible to extrapolate the size and the location of the absorber, its outflowing velocity and a direct estimation of the size of the X-ray emitting region ˜20 R_{g}.

  12. Temperature effect on the far infrared absorption features of aromatic-based Titan aerosol analogs

    NASA Astrophysics Data System (ADS)

    Gautier, T.; Trainer, M. G.; Loeffler, M. J.; Sebree, J.; Anderson, C. M.

    2014-12-01

    The detection of benzene at ppm levels in Titan's atmosphere[1] by Cassini's Ion and Neutral Mass Spectrometer (INMS) has enforced the idea that aromatic and heteroaromatic reaction pathways may play an important role in Titan's atmospheric chemistry, especially in the formation of aerosols. Indeed, Trainer et al.[2] showed that aromatic molecules are easily dissociated by ultraviolet radiation and can therefore contribute significantly to aerosol formation. Sebree et al. [3] used such a mixture of low concentration aromatic and/or heteroaromatic molecules (benzene, naphthalene, pyridine, quinoline and isoquinoline) to produce aerosol analogs and then analyzed their far infrared absorption spectra. Their study shows that such aerosols can reproduce some spectral features observed by Cassini's Composite InfraRed Spectrometer (CIRS) in the far infrared below 500cm-1 [4]. Aerosols absorption at such a low wavenumbers most likely results from lattice resonances within their structure[4,5], and this might be influenced by the temperature of the sample. In this work we investigated the influence of temperature on the absorption spectra of the aerosol samples studied in Sebree et al.[4]. We recorded spectra at 100K and 300K and this revealed variations in the total absorption with temperature, but no new absorption features were observed. Through this investigation we have also found an unexpected strong absorption band of cooled Silicon in the far infrared, which has never been reported in the literature. [1] Waite et al. Science 316 (5826) : 870-875 [2] Trainer et al. ApJL 766: L4, 2013 [3] Sebree et al. Icarus 236: 146-152, 2014 [4] Anderson et al. Icarus 212: 762-778, 2011 [5] Gautier et al. Icarus 221: 320-327, 2012

  13. Investigations on the 1.7 micron residual absorption feature in the vegetation reflection spectrum

    NASA Technical Reports Server (NTRS)

    Verdebout, J.; Jacquemoud, S.; Andreoli, G.; Hosgood, B.; Sieber, A.

    1993-01-01

    The detection and interpretation of the weak absorption features associated with the biochemical components of vegetation is of great potential interest to a variety of applications ranging from classification to global change studies. This recent subject is also challenging because the spectral signature of the biochemicals is only detectable as a small distortion of the infrared spectrum which is mainly governed by water. Furthermore, the interpretation is complicated by complexity of the molecules (lignin, cellulose, starch, proteins) which contain a large number of different and common chemical bonds. In this paper, we present investigations on the absorption feature centered at 1.7 micron; these were conducted both on AVIRIS data and laboratory reflectance spectra of leaves.

  14. Plant phenolics and absorption features in vegetation reflectance spectra near 1.66 μm

    USGS Publications Warehouse

    Kokaly, Raymond F.; Skidmore, Andrew K

    2015-01-01

    Past laboratory and field studies have quantified phenolic substances in vegetative matter from reflectance measurements for understanding plant response to herbivores and insect predation. Past remote sensing studies on phenolics have evaluated crop quality and vegetation patterns caused by bedrock geology and associated variations in soil geochemistry. We examined spectra of pure phenolic compounds, common plant biochemical constituents, dry leaves, fresh leaves, and plant canopies for direct evidence of absorption features attributable to plant phenolics. Using spectral feature analysis with continuum removal, we observed that a narrow feature at 1.66 μm is persistent in spectra of manzanita, sumac, red maple, sugar maple, tea, and other species. This feature was consistent with absorption caused by aromatic C-H bonds in the chemical structure of phenolic compounds and non-hydroxylated aromatics. Because of overlapping absorption by water, the feature was weaker in fresh leaf and canopy spectra compared to dry leaf measurements. Simple linear regressions of feature depth and feature area with polyphenol concentration in tea resulted in high correlations and low errors (% phenol by dry weight) at the dry leaf (r2 = 0.95, RMSE = 1.0%, n = 56), fresh leaf (r2 = 0.79, RMSE = 2.1%, n = 56), and canopy (r2 = 0.78, RMSE = 1.0%, n = 13) levels of measurement. Spectra of leaves, needles, and canopies of big sagebrush and evergreens exhibited a weak absorption feature centered near 1.63 μm, short ward of the phenolic compounds, possibly consistent with terpenes. This study demonstrates that subtle variation in vegetation spectra in the shortwave infrared can directly indicate biochemical constituents and be used to quantify them. Phenolics are of lesser abundance compared to the major plant constituents but, nonetheless, have important plant functions and ecological significance. Additional research is needed to advance our understanding of the

  15. Measurement and feature analysis of absorption spectra of four algal species

    NASA Astrophysics Data System (ADS)

    Zhu, Jianhua; Zhou, Hongli; Han, Bing; Li, Tongji

    2016-04-01

    Two methods for particulate pigments (i.e., quantitative filter technique, QFT, and in vivo measurement, InVivo, respectively) and two methods for dissolved pigments (i.e., Acetone Extracts, AceEx, and high-performance liquid chromatography, HPLC, respectively) were used to obtain the optical absorption coefficient spectra for cultures of four typical algal species. Through normalization and analysis of the spectra, it is shown that (1) the four methods are able to measure optical absorption spectra of particulate and/or dissolved pigments; (2) that the optical absorption spectra of particulate and dissolved pigments were consistent in terms of the peak position in the blue wavelength, and the difference of the peak position in the near infrared wavelength was ~10 nm between each other; and (3) that the leveling effect of the absorption spectra of particulate pigments was significant. These four methods can all effectively measure the absorption coefficients of phytoplankton pigments, while each one has its unique advantages in different applications. Therefore, appropriate method should be carefully selected for various application due to their intrinsic difference.

  16. Enhancement of light absorption in polyazomethines due to plasmon excitation on randomly distributed metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Wróbel, P.; Antosiewicz, T. J.; Stefaniuk, T.; Ciesielski, A.; Iwan, A.; Wronkowska, A. A.; Wronkowski, A.; Szoplik, T.

    2015-05-01

    In photovoltaic devices, metal nanoparticles embedded in a semiconductor layer allow the enhancement of solar-toelectric energy conversion efficiency due to enhanced light absorption via a prolonged optical path, enhanced electric fields near the metallic inclusions, direct injection of hot electrons, or local heating. Here we pursue the first two avenues. In the first, light scattered at an angle beyond the critical angle for reflection is coupled into the semiconductor layer and confined within such planar waveguide up to possible exciton generation. In the second, light is trapped by the excitation of localized surface plasmons on metal nanoparticles leading to enhanced near-field plasmon-exciton coupling at the peak of the plasmon resonance. We report on results of a numerical experiment on light absorption in polymer- (fullerene derivative) blends, using the 3D FDTD method, where exact optical parameters of the materials involved are taken from our recent measurements. In simulations we investigate light absorption in randomly distributed metal nanoparticles dispersed in polyazomethine-(fullerene derivative) blends, which serve as active layers in bulkheterojunction polymer solar cells. In the study Ag and Al nanoparticles of different diameters and fill factors are diffused in two air-stable aromatic polyazomethines with different chemical structures (abbreviated S9POF and S15POF) mixed with phenyl-C61-butyric acid methyl ester (PCBM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The mixtures are spin coated on a 100 nm thick Al layer deposited on a fused silica substrate. Optical constants of the active layers are taken from spectroscopic ellipsometry and reflectance measurements using a rotating analyzer type ellipsometer with auto-retarder performed in the wavelength range from 225 nm to 2200 nm. The permittivities of Ag and Al particles of diameters from 20 to 60 nm are assumed to be equal to those measured on 100 to 200 nm thick metal films.

  17. Absorption features in the x-ray spectrum of an ordinary radio pulsar.

    PubMed

    Kargaltsev, Oleg; Durant, Martin; Misanovic, Zdenka; Pavlov, George G

    2012-08-24

    The vast majority of known nonaccreting neutron stars (NSs) are rotation-powered radio and/or γ-ray pulsars. So far, their multiwavelength spectra have all been described satisfactorily by thermal and nonthermal continuum models, with no spectral lines. Spectral features have, however, been found in a handful of exotic NSs and were thought to be a manifestation of their unique traits. Here, we report the detection of absorption features in the x-ray spectrum of an ordinary rotation-powered radio pulsar, J1740+1000. Our findings bridge the gap between the spectra of pulsars and other, more exotic, NSs, suggesting that the features are more common in the NS spectra than they have been thought so far. PMID:22923576

  18. Changes on image texture features of breakfast flakes cereals during water absorption.

    PubMed

    Medina, Wenceslao T; Quevedo, Roberto A; Aguilera, José M

    2013-02-01

    Normally breakfast cereal flakes are consumed by pouring them into a bowl and covering them with fresh or cold milk. During this process the liquid uptake causes changes in the surface and internal matrix of breakfast cereals that influence texture and integrity. Some breakfast cereal as flakes have a translucent structure that could provide information about the solid matrix and air cells and how they change during liquid absorption. The objective of the study was to assess the image texture changes of corn flakes and frosted flakes during water absorption at 5, 15 and 25 °C, employing 11 image feature textures extracted from grey-level co-occurrence matrix and grey-level run length matrix (at three directions) and to relate the fractal dimension (FD) of images with rupture force (RF) reduction during soaking of both flakes at 5 °C. The most relevant result from principal component analysis calculated with a matrix of 54 (soaking times) × 22 (texture features), shows that it was possible to distinguish an isolated group consisting of different soaking times at the same water temperature in each breakfast cereal flakes evaluated, corroborating that superficial liquid imbibition is important during the liquid absorption process when flakes are soaked. Furthermore, standardized FD could be related to RF in the period when samples tend to search for an equilibrium state. PMID:23345324

  19. [Study on exploring for gas based on analysis of spectral absorption features].

    PubMed

    Xu, Da-Qi; Ni, Guo-Qiang; Jiang, Li-Li; Li, Ting; Ge, Shu-Le; Shu, Xian-Biao

    2007-11-01

    Reflectance spectra in the visible and near-infrared wavelength region provide a rapid and inexpensive means for determining the mineralogy of samples and obtaining information on chemical composition. Hydrocarbon microseepage theory establishes a cause-and-effect relation between oil and gas reservoirs and some special surface anomalies. Therefore the authors can explore for oil and gas by determining the reflectance spectra of surface anomalies. This determination can be fulfilled by means of field work and hyperspectral remote sensing. In the present paper, based on the analysis of reflectance spectra determined in the field of Qinghai X X area, firstly, a macroscopic feature of the reflectance spectra of typical observation points in the gas fields is presented. Secondly, absorption-band parameters of spectra such as the position, depth, width, and asymmetry are extracted. Based on the spectral absorption features of the spectra of 144 samples collected from the field, a spectral library for the Qinghai X X area is built to make the detection of the mineral alterations more rapid and reliable. Thirdly, two methods are improved and proposed to detect hydrocarbon microseepage using hydrocarbon absorption bands of reflectance spectra determined from the field. Finally, a linear unmixing model is studied based on the spectra of 144 samples so as to semi-quantitatively determine the abundance fractions of main minerals in the authors' studied area. PMID:18260381

  20. High-Velocity Absorption Features in FUSE Spectra of Eta Carinae

    NASA Astrophysics Data System (ADS)

    Sonneborn, G.; Iping, R. C.; Gull, T. R.; Vieira, G.

    2002-12-01

    Numerous broad (200 to 1000 km/sec) features in the FUSE spectrum (905-1187 A) of eta Carinae are identified as absorption by a forest of high-velocity narrow lines formed in the expanding circumstellar envelope. These features were previously thought to be P-Cygni lines arising in the wind of the central star. The features span a heliocentric velocity range of -140 to -580 km/sec and are seen prominently in low-ionization ground-state transitions (e.g. N I 1134-35, Fe II 1145-42, 1133, 1127-22, P II 1153, C I 1158) in addition to C III] 1176 A. The high-velocity components of the FUSE transitions have depths about 50% below the continuum. The identifications are consistent with the complex velocity structures seen in ground- and excited-state transitions of Mg I, Mg II, Fe II, V II, etc observed in STIS/E230H spectra (see accompanying posters by Gull, Vieira, and Danks). The origin of other broad features of similar width and depth in the FUSE spectrum, but without low-velocity ISM absorption, are unidentified. However, they are suspected of being absorption of singly-ionized iron-peak elements (e.g. Fe II, V II, Cr II) out of excited levels 1,000 to 20,000 cmE-1 above the ground state. The high-velocity features seen in Fe II 1145 are also present in Fe II 1608 (STIS/E140M), but are highly saturated in the latter. Since these transitions have nearly identical log (flambda) (1.998 vs. 2.080), the differences in the profiles are attributable to the different aperture sizes used (30x30 arcsec for FUSE, 0.2x0.2 arcsec for STIS/E140M). The high-velocity gas appears to be very patchy or has a small covering factor near the central star. Eta Carinae has been observed several times by FUSE over the past three years. The FUSE flux levels and spectral features in eta Car are essentially unchanged over the 2000 March to June 2002 period, establishing a baseline far-UV spectrum in advance of the predicted spectroscopic miniumum in 2003.

  1. High-Velocity Absorption Features in FUSE Spectra of Eta Carinae

    NASA Technical Reports Server (NTRS)

    Sonneborn, G.; Iping, R. C.; Gull, T. R.; Vieira, G.

    2003-01-01

    Numerous broad (200 to 1000 km/sec) features in the FUSE spectrum (905-1187 A) of eta Carinae are identified as absorption by a forest of high-velocity narrow lines formed in the expanding circumstellar envelope. These features were previously thought to be P-Cygni lines arising in the wind of the central star. The features span a heliocentric velocity range of -140 to -580 km/sec and are seen prominently in low-ionization ground-state transitions (e.g. N I 1134-35, Fe II 1145-42, 1133, 1127- 22, P II 1153, C I 1158) in addition to C III] 1176 A. The high-velocity components of the FUSE transitions have depths about 50% below the continuum. The identifications are consistent with the complex velocity structures seen in ground- and excited-state transitions of Mg I, Mg 11, Fe II, V II, etc observed in STIS/E230H spectra. The origin of other broad features of similar width and depth in the FUSE spectrum, but without low-velocity ISM absorption, are unidentified. However, they are suspected of being absorption of singly-ionized iron-peak elements (e.g. Fe II, V II, Cr II) out of excited levels 1,000 to 20,000 cmE-l above the ground state. The high-velocity features seen in Fe II 1145 are also present in Fe II 1608 (STIS/E140M), but are highly saturated in the latter. Since these transitions have nearly identical log (flambda) (1.998 vs. 2.080), the differences in the profiles are attributable to the different aperture sizes used (30 x 30 arcsec for FUSE, 0.2 x 0.2 arcsec for STIS/E140M). The high-velocity gas appears to be very patchy or has a small covering factor near the central star. Eta Carinae has been observed several times by FUSE over the past three years. The FUSE flux levels and spectral features in eta Car are essentially unchanged over the 2000 March to June 2002 period, establishing a baseline far-UV spectrum in advance of the predicted spectroscopic minimum in 2003.

  2. Time-dependent excitation and ionization modelling of absorption-line variability due to GRB 080310

    NASA Astrophysics Data System (ADS)

    Vreeswijk, P. M.; Ledoux, C.; Raassen, A. J. J.; Smette, A.; De Cia, A.; Woźniak, P. R.; Fox, A. J.; Vestrand, W. T.; Jakobsson, P.

    2013-01-01

    We model the time-variable absorption of Fe II, Fe III, Si II, C II and Cr II detected in Ultraviolet and Visual Echelle Spectrograph (UVES) spectra of gamma-ray burst (GRB) 080310, with the afterglow radiation exciting and ionizing the interstellar medium in the host galaxy at a redshift of z = 2.42743. To estimate the rest-frame afterglow brightness as a function of time, we use a combination of the optical VRI photometry obtained by the RAPTOR-T telescope array, which is presented in this paper, and Swift's X-Ray Telescope (XRT) observations. Excitation alone, which has been successfully applied for a handful of other GRBs, fails to describe the observed column density evolution in the case of GRB 080310. Inclusion of ionization is required to explain the column density decrease of all observed Fe II levels (including the ground state 6D9/2) and increase of the Fe III 7S3 level. The large population of ions in this latter level (up to 10% of all Fe III) can only be explained through ionization of Fe II, as a large fraction of the ionized Fe II ions (we calculate 31% using the Flexible Atomic and Cowan codes) initially populate the 7S3 level of Fe III rather than the ground state. This channel for producing a significant Fe III 7S3 level population may be relevant for other objects in which absorption lines from this level, the UV34 triplet, are observed, such as broad absorption line (BAL) quasars and η Carinae. This provides conclusive evidence for time-variable ionization in the circumburst medium, which to date has not been convincingly detected. However, the best-fit distance of the neutral absorbing cloud to the GRB is 200-400 pc, i.e. similar to GRB-absorber distance estimates for GRBs without any evidence for ionization. We find that the presence of time-varying ionization in GRB 080310 is likely due to a combination of the super-solar iron abundance ([Fe/H] = +0.2) and the low H I column density (log N(H i) = 18.7) in the host of GRB 080310. Finally

  3. On the Significance of Absorption Features in HST/COS Data

    NASA Astrophysics Data System (ADS)

    Keeney, Brian A.; Danforth, Charles W.; Stocke, John T.; France, Kevin; Green, James C.

    2012-08-01

    We present empirical scaling relations for the significance of absorption features detected in medium-resolution, far-UV spectra obtained with the Cosmic Origins Spectrograph (COS). These relations properly account for both the extended wings of the COS line-spread function and the non-Poissonian noise properties of the data, which we characterize for the first time, and predict limiting equivalent widths that deviate from the empirical behavior by <= 5% when the wavelength and Doppler parameter are in the ranges of λ = 1150-1750 Å and b > 10 km s-1. We have tested a number of co-addition algorithms and find the noise properties of individual exposures to be closer to the Poissonian ideal than are co-added data in all cases. For unresolved absorption lines, limiting equivalent widths for co-added data are 6% larger than limiting equivalent widths derived from individual exposures with the same signal-to-noise ratio. This ratio scales with b-value for resolved absorption lines, with co-added data having a limiting equivalent width that is 25% larger than individual exposures when b ≈ 150 km s-1. Our co-addition routine originally used a linear interpolation scheme, but has been modified to use nearest-neighbor interpolation instead, as a result of this testing. Consequently, we recommend that users who downloaded previous versions of our co-addition code upgrade to the latest version (ver. 2.0) at http://casa.colorado.edu/~danforth/costools.html.

  4. Ultraviolet spectra of quenched carbonaceous composite derivatives: Comparison to the '217 nanometer' interstellar absorption feature

    NASA Technical Reports Server (NTRS)

    Sakata, Akira; Wada, Setsuko; Tokunaga, Alan T.; Narisawa, Takatoshi; Nakagawa, Hidehiro; Ono, Hiroshi

    1994-01-01

    QCCs (quenched carbonaceous composite) are amorphus carbonaceous material formed from a hydrocarbon plasma. We present the UV-visible spectra of 'filmy QCC; (obtained outside of the beam ejected from the hydrocarbon plasma) and 'dark QCC' (obtained very near to the beam) for comparison to the stellar extinction curve. When filmy QCC is heated to 500-700 C (thermally altered), the wavelength of the absorption maximum increases form 204 nm to 220-222 nm. The dark QCC has an absorption maximum at 217-222 nm. In addition, the thermally altered filmy QCC has a slope change at about 500 nm which resmbles that in the interstellar extinction curve. The resemblance of the extinction curve of the QCCs to that of the interstellar medium suggests that QCC derivatives may be representative of the type of interstellar material that produces the 217 nm interstellar medium feature. The peak extinction of the dark QCC is higher than the average interstellar extinction curve while that of the thermally altered filmy QCC is lower, so that a mixture of dark and thermally altered filmy QCC can match the peak extinction observed in the interstellar medium. It is shown from electron micrographs that most of the thermally altered flimy QCC is in the form of small grainy structure less than 4 nm in diameter. This shows that the structure unit causing the 217-222 nm feature in QCC is very small.

  5. Photoacoustic Experimental System to Confirm Infrared Absorption Due to Greenhouse Gases

    ERIC Educational Resources Information Center

    Kaneko, Fumitoshi; Monjushiro, Hideaki; Nishiyama, Masayoshi; Kasai, Toshio; Harris, Harold H.

    2010-01-01

    An experimental system for detecting infrared absorption using the photoacoustic (PA) effect is described. It is aimed for use at high-school level to illustrate the difference in infrared (IR) absorption among the gases contained in the atmosphere in connection with the greenhouse effect. The experimental system can be built with readily…

  6. Removal of OH Absorption Bands Due to Pyrohydrolysis Reactions in Fluoride-Containing Borosilicate Glasses

    NASA Astrophysics Data System (ADS)

    Kobayashi, Keiji

    1997-05-01

    The purpose of this study is to decrease and to remove OH ions and H2O in borosilicate glasses. Fluoride-containing borosilicate glasses followed by dry-air-bubbling showed the significant decrease of OH absorption bands around 3500 cm-1. The decrease of OH absorption bands was elucidated by the use of pyrohydrolysis reactions in these glasses where fluoride ions react with OH ions or H2O during melting. The rates of the decrease of OH absorption bands substantially depend on high valence cations of fluorides. Particularly, the decrease rates of OH absorption coefficients were in the order of ZrF4-containing glass>AlF3-containing glass>ZnF2-containing glass. ZrF4-containing glass treated by dry-air-bubbling showed a good capability to remove OH absorption band. Fluoride-containing glasses showed the low flow point in comparison with fluoride-free glasses.

  7. Studying Absorption Line Feature in the Relativistic Jet Source GRS 1915+105

    NASA Technical Reports Server (NTRS)

    Tavani, Marco

    1998-01-01

    The galactic superluminal source GRS 1915+105 is among the most interesting objects in our Galaxy. It is subject to erratic accretion instabilities with energization of relativistic jets producing X-ray, optical and radio emission. This source was observed by ASCA on Sept. 27, 1994, April 20, 1995, October 23, 1996 and April 25, 1997 as part of a long timescale investigation. We detected strong variability of the source, and in particular the existence of burst/dip structure in October 1996 and April 1997. Clear evidence of transient absorption features at 6.7, 7.0 and 8.0 keV was obtained for the first time in September 1994 and April 1995. Given the phenomenology of plasmoid energization and ejection, these transient spectral features might be produced by material entrained in the radio jets or in other high-velocity outflows. Our contribution to the interpretation is to incorporate these observations into a overall theoretical picture for GRS 1915+105 also taking into account other observations by XTE and BSAX. The emerging picture is complex. The central source is subject to (most likely) super-Eddington instabilities mediated by magnetic field build-up, reconnection and dissipation in the form of blobs that eventually leads to the formation of transient spectral features from the surrounding of the plasmoid emitting region. A comprehensive theoretical investigation is in progress.

  8. On the Putative Detection of Z>0 X-Ray Absorption Features in the Spectrum of Mrk 421

    SciTech Connect

    Rasmussen, Andrew P.; Kahn, Steven M.; Paerels, Frits; Herder, Jan Willem den; Kaastra, Jelle; de Vries, Cor; /SRON, Utrecht

    2006-04-28

    In a series of papers, Nicastro et al. have claimed the detection of z > 0 O VII absorption features in the spectrum of Mrk 421 obtained with the Chandra Low Energy Transmission Grating Spectrometer (LETGS). We evaluate those claims in the context of a high quality spectrum of the same source obtained with the Reflection Grating Spectrometer (RGS) on XMM-Newton. The data comprise over 955 ksec of usable exposure time and more than 2.6 x 10{sup 4} counts per 50 m{angstrom} at 21.6 {angstrom}. We concentrate on the spectrally clean region (21.3 < {lambda} < 22.5 {angstrom}) where sharp features due to the astrophysically abundant O VII may reveal an intervening, warm-hot intergalactic medium (WHIM). In spite of the fact that the sensitivity of the RGS data is higher than that of the original LETGS data presented by Nicastro et al., we do not confirm detection of any of the intervening systems claimed to date. Rather, we detect only three unsurprising, astrophysically expected features down to the log (N{sub i}) {approx} 14.6 (3{sigma}) sensitivity level. Each of the two purported WHIM features is rejected with a statistical confidence that exceeds that reported for its initial detection. While we can not rule out the existence of fainter, WHIM related features in these spectra, we suggest that previous discovery claims were premature. A more recent paper by Williams et al. claims to have demonstrated that the RGS data we analyze here do not have the resolution or statistical quality required to confirm or deny the LETGS detections. We show that the Williams et al. reduction of the RGS data was highly flawed, leading to an artificial and spurious degradation of the instrument response. We carefully highlight the differences between our analysis presented here and those published by Williams et al.

  9. Detection of a Deep 3-μm Absorption Feature in the Spectrum of Amalthea (JV)

    NASA Astrophysics Data System (ADS)

    Takato, Naruhisa; Bus, Schelte J.; Terada, Hiroshi; Pyo, Tae-Soo; Kobayashi, Naoto

    2004-12-01

    Near-infrared spectra of Jupiter's small inner satellites Amalthea and Thebe are similar to those of D-type asteroids in the 0.8- to 2.5-micrometer wavelength range. A deep absorption feature is detected at 3 micrometers in the spectra of the trailing side of Amalthea, which is similar to that of the non-ice components of Callisto and can be attributed to hydrous minerals. These surface materials cannot be explained if the satellite formed at its present orbit by accreting from a circumjovian nebula. Amalthea and Thebe may be the remnants of Jupiter's inflowing building blocks that formed in the outer part or outside of the circumjovian nebula.

  10. Detection of a deep 3-microm absorption feature in the spectrum of Amalthea (JV).

    PubMed

    Takato, Naruhisa; Bus, Schelte J; Terada, Hiroshi; Pyo, Tae-Soo; Kobayashi, Naoto

    2004-12-24

    Near-infrared spectra of Jupiter's small inner satellites Amalthea and Thebe are similar to those of D-type asteroids in the 0.8- to 2.5-micrometer wavelength range. A deep absorption feature is detected at 3 micrometers in the spectra of the trailing side of Amalthea, which is similar to that of the non-ice components of Callisto and can be attributed to hydrous minerals. These surface materials cannot be explained if the satellite formed at its present orbit by accreting from a circumjovian nebula. Amalthea and Thebe may be the remnants of Jupiter's inflowing building blocks that formed in the outer part or outside of the circumjovian nebula. PMID:15618511

  11. Old stellar populations. 5: Absorption feature indices for the complete LICK/IDS sample of stars

    NASA Technical Reports Server (NTRS)

    Worthey, Guy; Faber, S. M.; Gonzalez, J. Jesus; Burstein, D.

    1994-01-01

    Twenty-one optical absorption features, 11 of which have been previously defined, are automatically measured in a sample of 460 stars. Following Gorgas et al., the indices are summarized in fitting functions that give index strengths as functions of stellar temperature, gravity, and (Fe/H). This project was carried out with the purpose of predicting index strengths in the integrated light of stellar populations of different ages and metallicities, but the data should be valuable for stellar studies in the Galaxy as well. Several of the new indices appear to be promising indicators of metallicity for old stellar populations. A complete list of index data and atmospheric parameters is available in computer-readable form.

  12. Monochromatic calculations of atmospheric radiative transfer due to molecular line absorption

    NASA Technical Reports Server (NTRS)

    Chou, M.-D.; Kouvaris, L.

    1986-01-01

    Sensitivity studies related to the effects of line cutoff, spectral resolution, and temperature and pressure interpolations in radiative transfer have been performed so that a data set of absorption coefficients for water vapor, CO2, and O3 may be created efficiently. Results show that computations of absorption coefficients are affected only slightly by cutting a line off at a wave number 190 times the Lorentz half width from the center, or equivalently, cutting off 0.33 percent of the line intensity from the wings. To achieve a relative cooling rate error smaller than 2 percent, it is sufficient to precompute the absorption coefficient at three temperatures (210, 250, and 290 K) and 19 pressures with Delta (log 10 p) = 0.2. The absorption coefficient at other conditions can be interpolated linearly with pressure and exponentially with a quadratic in temperature. For the spectral resolution the absorption coefficients can be adequately computed at 0.01, 0.002, 0.005, and 0.025/cm intervals in the thermal water vapor, the CO2 and O3 bands, and the solar water vapor bands, respectively, which limits the error to only a few percent in the cooling and heating rates. Using the precomputed absorption coefficients, repeated monochromatic calculations of atmospheric heating/cooling rates for radiation model developments and for comparison with less detailed calculations are no longer difficult.

  13. The X-shooter sample of GRB afterglow spectra: Properties of the absorption features

    NASA Astrophysics Data System (ADS)

    de Ugarte Postigo, Antonio

    2015-08-01

    Since its commissioning at ESO's Very Large Telescope in 2009, the X-shooter spectrograph has become the reference instrument in gamma-ray burst (GRB) afterglow spectroscopy. During this time our collaboration has collected more than 70 spectra of GRB afterglows, with redshifts ranging from 0.06 to 6.3. Thanks to their extreme luminosity and simple intrinsic shape, GRB spectra are optimal tools for the study of galactic environments at basically any redshift. Being produced by the death of short-lived massive stars, they are also tracers of star formation.I will present the sample of absorption spectral features identified in X-shooter's GRB spectra describing observation and analysis techniques. The different features are compared with the characteristics of the explosion (duration, spectral shape, energetics, etc.) and with the properties of the host galaxy (mass, age, etc.) to improve our understanding of the nature of the explosions and how they interact with their environments. Using the large redshift range of the spectra collection we perform studies of the evolution of GRB environments across the history of the Universe and their relation with the evolution of star formation.

  14. Evidence for Mg-rich carbonates on Mars from a 3.9 μm absorption feature

    NASA Astrophysics Data System (ADS)

    Palomba, Ernesto; Zinzi, Angelo; Cloutis, Edward A.; D'Amore, Mario; Grassi, Davide; Maturilli, Alessandro

    2009-09-01

    The origin and nature of the early atmosphere of Mars is still debated. The discovery of sulfate deposits on the surface, coupled with the evidence that there are not large abundances of carbonates detectable on Mars in the optically accessible part of the regolith, leaves open different paleoclimatic evolutionary pathways. Even if carbonates are responsible for the feature observed by TES and Mini-TES at 6.76 μm, alternative hypotheses suggest that it could be due to the presence of Hydrated Iron Sulfates (HIS). Carbonates can be discerned from HIS by investigating the spectral region in which a strong overtone carbonate band is present. The Planetary Fourier Spectrometer on board the Mars Express spacecraft has acquired several thousand martian spectra in the range 1.2-45 μm since January 2004, most of which show a weak absorption feature between 3.8 and 4 μm. A similar feature was observed previously from the Earth, but its origin could not be straightforwardly ascribed to surface materials, and specifically to carbonates. Here we show the surficial nature of this band that can be ascribed to carbonate mixed with the martian soil materials. The materials that best reproduce the detected feature are Mg-rich carbonates (huntite [CaMg 3(CO 3) 4] and/or magnesite [MgCO 3]). The presence of carbonates is demonstrated in both bright and dark martian regions. An evaluation of the likeliest abundance gives an upper limit of ˜10 wt%. The widespread distribution of carbonates supports scenarios that suggest carbonate formation occurred not by precipitation in a water-rich environment but by weathering processes.

  15. Sm3+:Ag NPs assisted modification in absorption features of magnesium tellurite glass

    NASA Astrophysics Data System (ADS)

    Yusoff, N. M.; Sahar, M. R.; Ghoshal, S. K.

    2015-01-01

    Metallic nanoparticles (NPs) assisted enhancements in absorption and emission cross-section of tellurite glass is the present challenge. The influences of samarium (Sm3+) ions and silver (Ag) NPs ratio on physical and optical absorption properties of melt quench synthesized magnesium tellurite glasses are reported. XRD patterns verify the amorphous nature of glasses. Glass density, molar volume and ionic packing fraction are discerned to be in the range of 4.92-5.0 g cm-3, 29.82-30.26 cm3 mol-1 and 0.452-0.446, respectively. Moderate reduction potential of tellurite glass converted Ag1+ to Ag0 via single step process and NPs are formed. TEM image manifest the existence of NPs of average diameter ∼16.94 nm having Gaussian size distribution. The significant changes in structural properties in the presence of Ag NPs are discussed in terms of TeO4 tetrahedra distortion and network depolymerization process. The Sm3+:Ag NPs dependent variation in physical properties are ascribed to the alteration in the number of bridging oxygen to non bridging (NB) one. Enhancement in absorption intensity due to the local field effects of Ag NPs is attributed to the changes in Sm-O bond strength. Optical energy band gap (2.81-3.18 eV) and Urbach energy (0.18-0.24 eV) are found increase and decrease, respectively with the increase of Sm3+:Ag NPs up to 1.33 then quenches and enhances, respectively thereafter which are related to the changes in cross-link and NBO numbers. The FTIR spectra reveal modification in network structures evidenced from vibrational wave-number shifts of TeO4 and TeO3 structural units. The observed notable increase in HOH vibration mode suggests its helpfulness in promoting the absorption of water and light. It is asserted that the physical, optical and structural properties of magnesium tellurite glass can be tuned by controlling Sm3+:Ag NPs.

  16. Radiative absorption enhancements due to the mixing state of atmospheric black carbon

    SciTech Connect

    Cappa, Christopher D.; Onasch, Timothy B.; Massoli, Paola; Worsnop, Douglas R.; Bates, Timothy S.; Cross, Eben S.; Davidovits, Paul; Hakala, Jani; Hayden, Katherine; Jobson, Bertram Thomas; Kolesar, K. R.; Lack, D. A.; Lerner, Brian M.; Li, Shao-Meng; Mellon, Daniel; Nuaaman, Ibraheem; Olfert, Jason; Petaja, Tuukka; Quinn, P. K.; Song, Chen; Subramanian, R.; Williams, Eric; Zaveri, Rahul A.

    2012-08-30

    Atmospheric particulate black carbon (BC) leads to warming of the Earth's climate. Many models that include forcing by BC assume that non-BC aerosol species internally mixed with BC enhance BC absorption, often by a factor of {approx}2. However, such model estimates have yet to be clearly validated through atmospheric observations. Here, we report on direct measurements of the absorption enhancement (Eabs) of BC in the atmosphere around California and find that it is negligible at 532 nm and much smaller than predicted from theoretical calculations that are uniquely constrained by observations, suggesting that the warming by BC may be significantly overestimated (factor of 2) in many climate models. Additionally, non-BC particulate matter is found to contribute {approx}10% to the total absorption at 405 nm.

  17. FE K EMISSION AND ABSORPTION FEATURES IN THE XMM-EPIC SPECTRUM OF THE SEYFERT GALAXY IC 4329A

    NASA Technical Reports Server (NTRS)

    Markowitz, A.; Reeves, J. N.; Braito, V.

    2001-01-01

    We present a re-analysis of the XMM-Newton long-look of the X-ray bright Seyfert galaxy IC 4329a. The Fe K bandpass is dominated by two peaks, consistent with emission from neutral or near-neutral Fe Ka and KP. A relativistic diskline model whereby both peaks are the result of one doubly-peaked diskline profile is found to be a poor description of the data. Models using two relativistic disklines are found to describe the emission profile well. A low-inclination, moderately-relativistic dual-diskline model is possible if the contribution from narrow components, due to distant material, is small or absent. A high-inclination, moderately relativistic profile for each peak is possible if there are roughly equal contributions from both the broad and narrow components. Upper limits on Fe XXV and Fe XXVI emission and absorption at the systemic velocity of IC 4329a are obtained. We also present the results of RXTE monitoring of this source obtained so far; the combined XMM-Newton and RXTE data sets allow us to explore the time-resolved spectral behavior of this source on time scales ranging from hours to 2 years. We find no strong evidence for variability of the Fe Ka emission line on any time scale probed, likely due to the minimal level of continuum variability. We detect a narrow absorption line, at a energy of 7.68 keV in the rest frame of the source; its significance has been confirmed using Monte Carlo simulations. This feature is most likely due to absorption from Fe XXVI blueshifted to approximately 0.1c relative to the systemic velocity, making IC 4329a the lowest-redshift AGN known with a high-velocity, highly-ionized outflow component. As is often the case with similar outflows seen in high-luminosity quasars, the estimated mass outflow rate is larger than the inflow accretion rate, signaling that the outflow represents a substantial portion of the total energy budget of the AGN. The outflow could arise from a radiatively-driven disk wind, or it may be in the

  18. Modeling Ionospheric HF/VHF Radio-Wave Absorption due to Solar Energetic Proton Events

    NASA Astrophysics Data System (ADS)

    Sauer, H. H.; Wilkinson, D. C.

    2007-12-01

    Simple, one-parameter, algorithms have been applied to the observed energetic proton flux as provided by the GOES series of satellites to yield estimates of the high latitude HF and VHF radio-wave absorption for both day and night respectively. The twilight response is obtained as a bi-linear function of the solar zenith angle at the observation positions, and the latitude dependence of the absorption region near the edge of the absorbing region (the polar caps) are estimated from extant models of geomagnetic cut-offs and their dependence on geomagnetic activity. The approximate inverse square frequency dependence of ionospheric absorption is used to translate across the HF/VHF range and predictions of the minimum duration of events are determined. Calculations of the polar cap absorption of HF radio waves have been performed for eleven larger Solar Energetic Proton (SEP) events during the period from 1992 through 2002 and the results compared to observations of 30 MHz Riometers operated by the AFGL and located at Thule, Greenland. While discrepancies between the estimated and observed absorption using these procedures occur, especially at low absorption levels, this model has operational value in view of its simplicity and its being the only extant model, to our knowledge, which treats solar-illumination, geomagnetic cutoff variation, and frequency effects, at least to first order. Specimen graphical representations of the north and south polar caps illustrate the output of the model for the peak of the 12 December 2006 solar proton event. Given sufficient interest, improvements to the methodology used here are practicable and could be expected to achieve accuracies to the order of 25% or better.

  19. Absorption lines in the spectrum of Q0248 + 4302 due to a foreground tidal tail

    SciTech Connect

    Sargent, W.L.W.; Steidel, C.C. California Univ., Berkeley )

    1990-08-01

    The strong absorption lines in the spectrum of the quasar Q0248 + 4302 are discussed. The absorption has been shown to be produced in a sinuous tidal tail which emanates from the nearby galaxy pair G0248 + 4302A,B. There is a velocity difference of about 260 km/s between the systemic redshift of the interacting galaxies and the redshift of the tidal tail at a galactocentric distance of about 11/h kpc. The large velocity spread observed in the tail gas is probably responsible for the unusual strength of the interstellar lines. 18 refs.

  20. Ca II and Na I absorption in the QSO S4 0248 + 430 due to an intervening galaxy

    NASA Technical Reports Server (NTRS)

    Womble, Donna S.; Junkkarinen, Vesa T.; Cohen, Ross D.; Burbidge, E. Margaret

    1990-01-01

    Observations of the QSO S4 0248 + 430 and a nearby anonymous galaxy are presented. Two absorption components are found in both Ca II H and K and Na I D1 and D2 at z(a) = 0.0515, 0.0523. Column densities of log N(Ca II) = 13.29, 13.50, and log N(Na I) = 13.79, 14.18 are found for z(a) = 0.0515, 0.0523 absorption systems, respectively. The column density ratios imply considerable calcium depletion and disk-type absorbing gas. At least one and possibly both absorption components are produced by high-velocity gas. A broadband image of the field shows an asymmetrical armlike feature or possible tidal tail covering and extending past the position of the QSO. The presence of this extended feature and the apparent difference between the absorption velocities and galaxy rotation velocity suggest that the absorbing gas is not ordinary disk gas, but rather is a result of tidal disruption.

  1. Analysis of the alterations in porosity features of some natural stones due to thermal effect.

    PubMed

    Ugur, I; Sengun, N; Demirdag, S; Altindag, R

    2014-07-01

    Three types of commercially available carbonate rocks were used in the study to determine the effect of thermal treatment in the range from 100 °C to 500 °C on porosity features in terms of two different approaches such as pore shape factor and quality index values. The ratio of the ultrasonic velocity measurements before and after water saturation was used to differentiate porosity of pores from porosity of cracks under varying temperatures. It was found that, pores in Burdur Beige and Usak White are in the form of cracks, which are situated through inner structure. On the other hand, pores in Patara Limestone are in the form of porosity with lower pore shape factor values. Quality index calculation is another approach based on the comparison of the measured and theoretical ultrasonic velocity values. When the rocks were subjected to higher temperatures, internal stress was developed, crack lengths and numbers were increased and finally the higher pore shape factor and lower quality index values were obtained. This situation was proven by the higher water absorption values for all the stone types with the higher pore shape factor and lower quality index values depend on the noticeable increase in effective porosity values. PMID:24529822

  2. The origin of blueshifted absorption features in the X-ray spectrum of PG 1211+143: outflow or disc

    NASA Astrophysics Data System (ADS)

    Gallo, L. C.; Fabian, A. C.

    2013-07-01

    In some radio-quiet active galactic nuclei (AGN), high-energy absorption features in the X-ray spectra have been interpreted as ultrafast outflows (UFOs) - highly ionized material (e.g. Fe XXV and Fe XXVI) ejected at mildly relativistic velocities. In some cases, these outflows can carry energy in excess of the binding energy of the host galaxy. Needless to say, these features demand our attention as they are strong signatures of AGN feedback and will influence galaxy evolution. For the same reason, alternative models need to be discussed and refuted or confirmed. Gallo and Fabian proposed that some of these features could arise from resonance absorption of the reflected spectrum in a layer of ionized material located above and corotating with the accretion disc. Therefore, the absorbing medium would be subjected to similar blurring effects as seen in the disc. A priori, the existence of such plasma above the disc is as plausible as a fast wind. In this work, we highlight the ambiguity by demonstrating that the absorption model can describe the ˜7.6 keV absorption feature (and possibly other features) in the quasar PG 1211+143, an AGN that is often described as a classic example of a UFO. In this model, the 2-10 keV spectrum would be largely reflection dominated (as opposed to power law dominated in the wind models) and the resonance absorption would be originating in a layer between about 6 and 60 gravitational radii. The studies of such features constitute a cornerstone for future X-ray observatories like Astro-H and Athena+. Should our model prove correct, or at least important in some cases, then absorption will provide another diagnostic tool with which to probe the inner accretion flow with future missions.

  3. A case of consciousness disturbance resulting from severe hypothyroidism due to chronic thyroiditis and excess iodine absorption.

    PubMed

    Hayashi, Masayuki; Onodera, Kazunari; Suzuki, Kengo; Kataoka, Yuko; Tachikawa, Kazushige; Riku, Shigeo; Tanaka, Hiroshi

    2011-01-01

    An 82-year-old Japanese man had consciousness disturbance due to severe hypothyroidism triggered by percutaneous absorption of iodine from an iodine-containing ointment used in diabetic gangrene treatment. Laboratory data revealed extremely high urinary iodine concentrations, and chronic thyroiditis-induced hypothyroidism. Excess iodine intake can also cause hypothyroidism. It was unlikely that iodine intoxication or Hashimoto's encephalopathy had caused the consciousness disturbance. The patient regained consciousness after discontinuing the use of the ointment and commencing thyroid hormone therapy. We conclude that consciousness disturbance resulted from severe hypothyroidism caused by chronic thyroiditis and excess iodine absorption. PMID:22041370

  4. A search for ultraviolet circumstellar gas absorption features in alpha Piscis Austrinus (Fomalhaut), a possible Beta Pictoris-like system

    NASA Technical Reports Server (NTRS)

    Cheng, K.-P.; Bruhweiler, Fred C.; Kondo, Yoji

    1994-01-01

    Archival high-dispersion International Ultraviolet Explorer (IUE) spectra have been used to search for circumstellar gas absorption features in alpha PsA (A3 V), a nearby (6.7 pc) proto-planetary system candidate. Recent sub-millimeter mapping observations around the region of alpha PsA indicate a spatially resolved dust disk like the one seen around Beta Pic. To determine how closely this putative disk resembles that of Beta Pic, we have searched for signatures of circumstellar gaseous absorption in all the available IUE high-dispersion data of alpha PsA. Examination of co-added IUE spectra shows weak circumstellar absorptions from excited levels in the resonance multiplet of Fe II near 2600 A. We also conclude that the sharp C I feature near 1657 A, previously identified as interstellar absorption toward alpha PsA, likely has a circumstellar origin. However, because the weakness of these absorption features, we will consider the presence of circumstellar gas as tentative and should be verified by using the Goddard High-Resolution Spectrograph aboard the Hubble Space Telescope. No corresponding circumstellar absorption is detected in higher ionization Fe III and Al III. Since the collisionally ionized nonphotospheric Al III resonance absorption seen in Beta Pic is likely formed close to the stellar surface, its absence in the UV spectra of alpha PsA could imply that, in contrast with Beta Pic, there is no active gaseous disk infall onto the central star. In the alpha PsA gaseous disk, if we assume a solar abundance for iron and all the iron is in the form of Fe II, plus a disk temperature of 5000 K, the Fe II UV1 absorption at 2611.8743 A infers a total hydrogen column density along the line of sight through the circumstellar disk of N(H) approximately equals 3.8 x 10(exp 17)/cm.

  5. Bulk damage and absorption in fused silica due to high-power laser applications

    NASA Astrophysics Data System (ADS)

    Nürnberg, F.; Kühn, B.; Langner, A.; Altwein, M.; Schötz, G.; Takke, R.; Thomas, S.; Vydra, J.

    2015-11-01

    Laser fusion projects are heading for IR optics with high broadband transmission, high shock and temperature resistance, long laser durability, and best purity. For this application, fused silica is an excellent choice. The energy density threshold on IR laser optics is mainly influenced by the purity and homogeneity of the fused silica. The absorption behavior regarding the hydroxyl content was studied for various synthetic fused silica grades. The main absorption influenced by OH vibrational excitation leads to different IR attenuations for OH-rich and low-OH fused silica. Industrial laser systems aim for the maximum energy extraction possible. Heraeus Quarzglas developed an Yb-doped fused silica fiber to support this growing market. But the performance of laser welding and cutting systems is fundamentally limited by beam quality and stability of focus. Since absorption in the optical components of optical systems has a detrimental effect on the laser focus shift, the beam energy loss and the resulting heating has to be minimized both in the bulk materials and at the coated surfaces. In collaboration with a laser research institute, an optical finisher and end users, photo thermal absorption measurements on coated samples of different fused silica grades were performed to investigate the influence of basic material properties on the absorption level. High purity, synthetic fused silica is as well the material of choice for optical components designed for DUV applications (wavelength range 160 nm - 260 nm). For higher light intensities, e.g. provided by Excimer lasers, UV photons may generate defect centers that effect the optical properties during usage, resulting in an aging of the optical components (UV radiation damage). Powerful Excimer lasers require optical materials that can withstand photon energy close to the band gap and the high intensity of the short pulse length. The UV transmission loss is restricted to the DUV wavelength range below 300 nm and

  6. Features of X-ray Absorption Densitometry of Large-size Objects with Variable Thickness

    NASA Astrophysics Data System (ADS)

    Osipov, S.; Chakhlov, S.; Osipov, O.; Badin, S.; Abashkin, A.

    2016-01-01

    Features of formation and processing of the primary radiometric signals in the digital high-energy X-ray absorption densitometers for the homogeneous objects with variable thickness are examined. The densitometer's equation based on the polynomial approximation of the object's ray thickness dependence from its mass thickness is proposed. Guidance to select the capacity of the analog-digital converter is given. There is one example of the densitometer's equation coefficients calculation to examine the carbon, aluminum and steel wares with the mass density from 15 to 80 g/cm2. It was shown that disagreement of the experimental and estimated values of the ray thickness for the similar mass thicknesses of the testing object is conditioned by the scattered radiation. On the high-energy digital radiography set with the X-ray source - the betatron MIB-4.5/9 the accuracy of the experimental estimation of the density was within 0.0086 g/cm3 for the steel ware thickness from 25 to 100 mm.

  7. A variable absorption feature in the X-ray spectrum of a magnetar.

    PubMed

    Tiengo, Andrea; Esposito, Paolo; Mereghetti, Sandro; Turolla, Roberto; Nobili, Luciano; Gastaldello, Fabio; Götz, Diego; Israel, Gian Luca; Rea, Nanda; Stella, Luigi; Zane, Silvia; Bignami, Giovanni F

    2013-08-15

    Soft-γ-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slowly rotating, isolated neutron stars that sporadically undergo episodes of long-term flux enhancement (outbursts) generally accompanied by the emission of short bursts of hard X-rays. This behaviour can be understood in the magnetar model, according to which these sources are mainly powered by their own magnetic energy. This is supported by the fact that the magnetic fields inferred from several observed properties of SGRs and AXPs are greater than-or at the high end of the range of-those of radio pulsars. In the peculiar case of SGR 0418+5729, a weak dipole magnetic moment is derived from its timing parameters, whereas a strong field has been proposed to reside in the stellar interior and in multipole components on the surface. Here we show that the X-ray spectrum of SGR 0418+5729 has an absorption line, the properties of which depend strongly on the star's rotational phase. This line is interpreted as a proton cyclotron feature and its energy implies a magnetic field ranging from 2 × 10(14) gauss to more than 10(15) gauss. PMID:23955229

  8. Atmospheric-water absorption features near 2.2 micrometers and their importance in high spectral resolution remote sensing

    NASA Technical Reports Server (NTRS)

    Kruse, F. A.; Clark, R. N.

    1986-01-01

    Selective absorption of electromagnetic radiation by atmospheric gases and water vapor is an accepted fact in terrestrial remote sensing. Until recently, only a general knowledge of atmospheric effects was required for analysis of remote sensing data; however, with the advent of high spectral resolution imaging devices, detailed knowledge of atmospheric absorption bands has become increasingly important for accurate analysis. Detailed study of high spectral resolution aircraft data at the U.S. Geological Survey has disclosed narrow absorption features centered at approximately 2.17 and 2.20 micrometers not caused by surface mineralogy. Published atmospheric transmission spectra and atmospheric spectra derived using the LOWTRAN-5 computer model indicate that these absorption features are probably water vapor. Spectral modeling indicates that the effects of atmospheric absorption in this region are most pronounced in spectrally flat materials with only weak absorption bands. Without correction and detailed knowledge of the atmospheric effects, accurate mapping of surface mineralogy (particularly at low mineral concentrations) is not possible.

  9. Variability, absorption features, and parent body searches in "spectrally featureless" meteorite reflectance spectra: Case study - Tagish Lake

    NASA Astrophysics Data System (ADS)

    Izawa, M. R. M.; Craig, M. A.; Applin, D. M.; Sanchez, J. A.; Reddy, V.; Le Corre, L.; Mann, P.; Cloutis, E. A.

    2015-07-01

    Reflectance spectra of many asteroids and other Solar System bodies are commonly reported as "featureless". Here, we show that weak but consistently detectable absorption bands are observable in 200-2500 nm spectra of the Tagish Lake meteorite, a likely compositional and spectral analogue for low-albedo, "spectrally-featureless" asteroids. Tagish Lake presents a rare opportunity to study multiple lithologies within a single meteorite. Reflectance spectra of Tagish Lake display significant variation between different lithologies. The spectral variations are due in part to mineralogical variations between different Tagish Lake lithologies. Ultraviolet reflectance spectra (200-400 nm), few of which have been reported in the literature to date, reveal albedo and spectral ratio variations as a function of mineralogy. Similarly visible-near infrared reflectance spectra reveal variations in albedo, spectral slope, and the presence of weak absorption features that persist across different lithologies and can be attributed to various phases present in Tagish Lake. These observations demonstrate that significant spectral variability may exist between different lithologies of Tagish Lake, which may affect the interpretation of potential source body spectra. It is also important to consider the spectral variability within the meteorite before excluding compositional links between possible parent bodies in the main belt and Tagish Lake. Tagish Lake materials may also be spectral-compositional analogues for materials on the surfaces of other dark asteroids, including some that are targets of upcoming spacecraft missions. Tagish Lake has been proposed as a spectral match for 'ultra-primitive' D or P-type asteroids, and the variability reported here may be reflected in spatially or rotationally-resolved spectra of possible Tagish Lake parent bodies and source objects in the Near-Earth Asteroid population. A search for objects with spectra similar to Tagish Lake has been carried

  10. Tunable Optical Limiting Action due to Non-linear Absorption in ZnO/Ag Nanocomposites

    NASA Astrophysics Data System (ADS)

    Radhu, S.; Vijayan, C.; Sandeep, Suchand; Philip, Reji

    2011-07-01

    ZnO/Ag nanocomposites with different silver concentration are successfully synthesized by solvothermal method. The characterization of the as- synthesized samples is done using XRD, UV-visible spectroscopy and HRTEM and the results indicate that the composites consist of silver nanoparticles attached to the ZnO nanoparticles. The optical non-linearity in these samples is studied using open aperture Z-scan technique and the experimental results agree well with a theoretical model involving two- photon absorption. It is found that the parameters of optical limiting can be tuned in a broad band by varying the silver concentration in the samples.

  11. Enhancement of microbial motility due to advection-dependent nutrient absorption

    NASA Astrophysics Data System (ADS)

    Condat, Carlos A.; di Salvo, Mario E.

    2014-03-01

    In their classical work, Berg and Purcell [Biophys. J. 20, 193 (1977)] concluded that the motion of a small microorganism would not significantly increase its nutrient uptake rate, if the nutrient consisted of high diffusivity particles. As a result, it has been generally assumed that nutrient transport to small microorganisms such as bacteria is dominated by molecular diffusion and that swimming and feeding currents play a negligible role. On the other hand, recent studies have found that flagellar motion may increase advection-mediated uptake. We formulate a model to investigate the hypothesis that fast-moving microbes may enhance their swimming speed by taking advantage of advection to increase nutrient absorption. Surprisingly, using realistic parameter values for bacteria and algae, we find that even modest increases in nutrient absorption may lead to a significant increase of the microbial speed. We also show that, optimally, the rate of effective energy transfer to the microbial propulsion system should be proportional to the speed for slow motion, while it should be proportional to a power of the speed close to two for fast motion. We are grateful to SECyT-UNC and CONICET, Argentina, for financial support.

  12. Changes of color and water-absorption of Hungarian porous limestone due to biomineralization

    NASA Astrophysics Data System (ADS)

    Juhász, P.; Kopecskó, K.

    2013-12-01

    Bacteria induced calcium carbonate precipitation nowadays is a widely examined process being a possible alternative for traditional stone conservation methods. While research has been mostly limited to laboratory measurements, application connected, further in situ experiments should be performed in order to evaluate the applicability of the method. In our experiment, several bio-based treating compounds were compared, which have already been analyzed in different laboratories. Method for the treatment was based on the treatment of a French research group, and the compounds were applied on Hungarian porous limestone slabs, in situ. For inoculation bacteria strains Bacillus cereus and Myxococcus xanthus were used, and non-inoculated compounds were also analyzed. After the treatment, specimens were analyzed by means of discoloration effect, water absorption and migration characteristics. Almost all the treating compounds gave favorable or acceptable results for the examined properties, comparing to the properties measured in the non-cured state. Measurements on the chromatic- and on the water absorption aspects gave significant results, while further measurements are running for the more exact evaluation of the migration characteristics, i.e. effective migration depth and wetted volume.

  13. Analysis of simultaneous emission and absorption Ti spectral features observed with the MMI instrument in OMEGA implosions

    NASA Astrophysics Data System (ADS)

    Joshi, Tirtha; Johns, Heather; Mayes, Daniel; Durmaz, Tunay; Mancini, Roberto; Tommasini, Riccardo; Delettrez, Jack; Regan, Sean; Nagayama, Taisuke

    2012-10-01

    We discuss the observation and analysis of spectra from titanium-doped OMEGA direct-drive implosions. The targets were spherical plastic shells with a submicron Ti-doped tracer-layer initially located on the inner surface of the shell and filled with deuterium gas. The x-ray signal from the titanium tracer is observed at the collapse of the implosion and recorded with a streaked spectrometer (SSCA) and three identical gated,multi-monochromatic x-ray imager (MMI) instruments that view the implosion along three quasi-orthogonal lines-of-sight. Both streaked and MMI data show simultaneous emission and absorption features due to titanium K-shell line transitions but only the MMI data permits to diagnose the tracer's spatial properties in the core. To this end, MMI data were processed to obtain narrow-band images and spatially-resolved spectra.footnotetextT. Nagayama et al., J. App. Phys.109, 093303 (2011). Abel inversion of angle-averaged image intensity profiles reveal the spatial distribution of the titanium tracer in the core, while detailed analysis of the space-resolved spectra yields temperature, density and mixing distributions. Results are presented for several shell thicknesses and implosions driven with different laser pulse shapes.

  14. Surface vs. atmospheric origin of 2.1-2.5 micron absorption features in the Martian spectrum

    NASA Technical Reports Server (NTRS)

    Bell, James F., III; Crisp, David

    1992-01-01

    For 20 years the origin of subtle absorption features in the spectrum of Mars near 2.3 micro-m ('K' band: 1.9-2.5 micro-m) has been debated. This spectral region contains gaseous absorption features predominantly from CO2 and CO on Mars and from telluric H2O and CO2. The authors have obtained new higher spectral resolution telescopic K band spectra of 10 surface regions using the Infrared Telescope Facility (IRTF) at Mauna Kea during 1990. The goals were to confirm the existence of broad features seen at lower spectral resolution and to determine whether these bands are caused by atmospheric gases, surface (or airborne dust) minerals, or a combination of both.

  15. [Study on intestinal absorption features of oligosaccharides in Morinda officinalis How. with sigle-pass perfusion].

    PubMed

    Deng, Shao-Dong; Zhang, Peng; Lin, Li; Xiao, Feng-Xia; Lin, Jing-Ran

    2015-01-01

    To study the in situ intestinal absorption of five oligosaccharides contained in Morinda officinalis How. (sucrose, kestose, nystose, 1F-Fructofuranosyinystose and Bajijiasu). The absorption of the five oligosaccharides in small intestine (duodenum, jejunum and ileum) and colon of rats and their contents were investigated by using in situ single-pass perfusion model and HPLC-ELSD. The effects of drug concentration, pH in perfusate and P-glycoprotein inhibitor on the intestinal absorption were investigated to define the intestinal absorption mechanism of the five oligosaccharides in rats. According to the results, all of the five oligosaccharides were absorbed in the whole intestine, and their absorption rates were affected by the pH of the perfusion solution, drug concentration and intestinal segments. Verapamil Hydrochloride could significantly increase the absorptive amount of sucrose and Bajijiasu, suggesting sucrose and Bajijiasu are P-gp's substrate. The five oligosaccharides are absorbed mainly through passive diffusion in the intestinal segments, without saturated absorption. They are absorbed well in all intestines and mainly in duodenum and jejunum. PMID:25993803

  16. Soliton Formation and Superluminality Effect due to Nonlinear Absorption of Femtosecond Laser Pulse Energy by the Medium Containing Nanorods

    NASA Astrophysics Data System (ADS)

    Trofimov, Vyacheslav A.; Lysak, Tatiana M.

    2016-02-01

    We investigate a femtosecond pulse propagation in a medium, containing nanorods, with taking into account the dependence of multi-photon absorption from the aspect ratio of nanorods. Nanorods melting due to the laser energy absorption leads to the non-stationary interaction of laser pulse with the medium and time-dependent nanorod aspect ratio changing. Under certain conditions, we found out the soliton-like mode of a laser pulse propagation and the superluminality effect: acceleration of light (fast light) in comparison with light propagation in a linear medium. We discuss a physical mechanism of superluminality effect for considering laser pulse propagation. Using spatio-temporal analogy, one can see the similarity between the pulse centre evolution along longitudinal coordinate and the beam centre evolution under the infrared optical radiation propagation in a cloud, or fog, which moves across the beam, with taking into account its thermal blooming.

  17. An evaluation of techniques for the extraction of mineral absorption features from high spectral resolution remote sensing data

    NASA Technical Reports Server (NTRS)

    Rast, Michael; Hook, Simon J.; Alley, Ronald E.; Elvidge, Christopher D.

    1991-01-01

    Airborne Visible/Infrared Imaging Spectrometer data covering the wavelength range between 2000 and 2400 nm are examined for their ability to display the diagnostic mineral absorption features of certain alteration minerals, employing various data processing techniques. The techniques may be separated into two broad categories: scene based techniques that use parameters derived from the data themselves, and correction techniques utilizing external information such as solar/atmospheric models. Results indicate that the data corrected utilizing the LOWTRAN 7 atmospheric transfer code constrained with local weather station data are the most effective at showing the diagnostic absorption features of the regions of known mineralogy and introduce the least number of artifacts into the data.

  18. Detection of dynamic background due to swaying movements from motion features.

    PubMed

    Pham, Duc-Son; Arandjelović, Ognjen; Venkatesh, Svetha

    2015-01-01

    Dynamically changing background (dynamic background) still presents a great challenge to many motion-based video surveillance systems. In the context of event detection, it is a major source of false alarms. There is a strong need from the security industry either to detect and suppress these false alarms, or dampen the effects of background changes, so as to increase the sensitivity to meaningful events of interest. In this paper, we restrict our focus to one of the most common causes of dynamic background changes: 1) that of swaying tree branches and 2) their shadows under windy conditions. Considering the ultimate goal in a video analytics pipeline, we formulate a new dynamic background detection problem as a signal processing alternative to the previously described but unreliable computer vision-based approaches. Within this new framework, we directly reduce the number of false alarms by testing if the detected events are due to characteristic background motions. In addition, we introduce a new data set suitable for the evaluation of dynamic background detection. It consists of real-world events detected by a commercial surveillance system from two static surveillance cameras. The research question we address is whether dynamic background can be detected reliably and efficiently using simple motion features and in the presence of similar but meaningful events, such as loitering. Inspired by the tree aerodynamics theory, we propose a novel method named local variation persistence (LVP), that captures the key characteristics of swaying motions. The method is posed as a convex optimization problem, whose variable is the local variation. We derive a computationally efficient algorithm for solving the optimization problem, the solution of which is then used to form a powerful detection statistic. On our newly collected data set, we demonstrate that the proposed LVP achieves excellent detection results and outperforms the best alternative adapted from existing art in

  19. Effect of a drag force due to absorption of solar radiation on solar sail orbital dynamics

    NASA Astrophysics Data System (ADS)

    Kezerashvili, Roman Ya.; Vázquez-Poritz, Justin F.

    2013-03-01

    While solar electromagnetic radiation can be used to propel a solar sail, it is shown that the Poynting-Robertson effect related to the absorbed portion of the radiation leads to a drag force in the transversal direction. The Poynting-Robertson effect is considered for escape trajectories, Heliocentric bound orbits and non-Keplerian bound orbits. For escape trajectories, this drag force diminishes the cruising velocity, which has a cumulative effect on the Heliocentric distance. For Heliocentric and non-Keplerian bound orbits, the Poynting-Robertson effect decreases its orbital speed, thereby causing it to slowly spiral towards the Sun. Since the Poynting-Robertson effect is due to the absorbed portion of the electromagnetic radiation, degradation of a solar sail implies that this effect becomes enhanced during a mission.

  20. Ultraviolet-visible absorptive features of water extractable and humic fractions of animal manure and compost

    Technology Transfer Automated Retrieval System (TEKTRAN)

    UV-vis spectroscopy is a useful tool for characterizing water extractable or humic fractions of natural organic matter (WEOM). Whereas the whole UV-visible spectra of these fractions are more or less featureless, the specific UV absorptivity at 254 and 280 nm as well as spectral E2/E3 and E4/E6 rat...

  1. Preparation of Honeycomb SnO₂ Foams and Configuration-Dependent Microwave Absorption Features.

    PubMed

    Zhao, Biao; Fan, Bingbing; Xu, Yawei; Shao, Gang; Wang, Xiaodong; Zhao, Wanyu; Zhang, Rui

    2015-12-01

    Ordered honeycomb-like SnO2 foams were successfully synthesized by means of a template method. The honeycomb SnO2 foams were analyzed by X-ray diffraction (XRD), thermogravimetric and differential scanning calorimetry (TG-DSC), laser Raman spectra, scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR). It can be found that the SnO2 foam configurations were determined by the size of polystyrene templates. The electromagnetic properties of ordered SnO2 foams were also investigated by a network analyzer. The results reveal that the microwave absorption properties of SnO2 foams were dependent on their configuration. The microwave absorption capabilities of SnO2 foams were increased by increasing the size of pores in the foam configuration. Furthermore, the electromagnetic wave absorption was also correlated with the pore contents in SnO2 foams. The large and high amounts pores can bring about more interfacial polarization and corresponding relaxation. Thus, the perfect ordered honeycomb-like SnO2 foams obtained in the existence of large amounts of 322 nm polystyrene spheres showed the outstanding electromagnetic wave absorption properties. The minimal reflection loss (RL) is -37.6 dB at 17.1 GHz, and RL less than -10 dB reaches 5.6 GHz (12.4-18.0 GHz) with thin thickness of 2.0 mm. The bandwidth (<-10 dB, 90% microwave dissipation) can be monitored in the frequency regime of 4.0-18.0 GHz with absorber thickness of 2.0-5.0 mm. The results indicate that these ordered honeycomb SnO2 foams show the superiorities of wide-band, high-efficiency absorption, multiple reflection and scatting, high antioxidation, lightweight, and thin thickness. PMID:26552325

  2. Critical coupling and coherent perfect absorption for ranges of energies due to a complex gain and loss symmetric system

    SciTech Connect

    Hasan, Mohammad; Ghatak, Ananya; Mandal, Bhabani Prasad

    2014-05-15

    We consider a non-Hermitian medium with a gain and loss symmetric, exponentially damped potential distribution to demonstrate different scattering features analytically. The condition for critical coupling (CC) for unidirectional wave and coherent perfect absorption (CPA) for bidirectional waves are obtained analytically for this system. The energy points at which total absorption occurs are shown to be the spectral singular points for the time reversed system. The possible energies at which CC occurs for left and right incidence are different. We further obtain periodic intervals with increasing periodicity of energy for CC and CPA to occur in this system. -- Highlights: •Energy ranges for CC and CPA are obtained explicitly for complex WS potential. •Analytical conditions for CC and CPA for PT symmetric WS potential are obtained. •Conditions for left and right CC are shown to be different. •Conditions for CC and CPA are shown to be that of SS for the time reversed system. •Our model shows the great flexibility of frequencies for CC and CPA.

  3. Form drag in rivers due to small-scale natural topographic features: 2. Irregular sequences

    USGS Publications Warehouse

    Kean, J.W.; Smith, J.D.

    2006-01-01

    The size, shape, and spacing of small-scale topographic features found on the boundaries of natural streams, rivers, and floodplains can be quite variable. Consequently, a procedure for determining the form drag on irregular sequences of different-sized topographic features is essential for calculating near-boundary flows and sediment transport. A method for carrying out such calculations is developed in this paper. This method builds on the work of Kean and Smith (2006), which describes the flow field for the simpler case of a regular sequence of identical topographic features. Both approaches model topographic features as two-dimensional elements with Gaussian-shaped cross sections defined in terms of three parameters. Field measurements of bank topography are used to show that (1) the magnitude of these shape parameters can vary greatly between adjacent topographic features and (2) the variability of these shape parameters follows a lognormal distribution. Simulations using an irregular set of topographic roughness elements show that the drag on an individual element is primarily controlled by the size and shape of the feature immediately upstream and that the spatial average of the boundary shear stress over a large set of randomly ordered elements is relatively insensitive to the sequence of the elements. In addition, a method to transform the topography of irregular surfaces into an equivalently rough surface of regularly spaced, identical topographic elements also is given. The methods described in this paper can be used to improve predictions of flow resistance in rivers as well as quantify bank roughness.

  4. Determination of the in-flight spectral calibration of AVIRIS using atmospheric absorption features

    NASA Technical Reports Server (NTRS)

    Green, Robert O.

    1995-01-01

    Spectral calibration of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) as data are acquired in flight is essential to quantitative analysis of the measured upwelling spectral radiance. In each spectrum measured by AVIRIS in flight, there are numerous atmospheric gas absorption bands that drive this requirement for accurate spectral calibration. If the surface and atmospheric properties are measured independently, these atmospheric absorption bands may be used to deduce the in-flight spectral calibration of an imaging spectrometer. Both the surface and atmospheric characteristics were measured for a calibration target during an in-flight calibration experiment held at Lunar Lake, Nevada on April 5, 1994. This paper uses upwelling spectral radiance predicted for the calibration target with the MODTRAN radiative transfer code to validate the spectral calibration of AVIRIS in flight.

  5. Specific features of optical absorption in rare-earth orthoaluminate DyAlO3

    NASA Astrophysics Data System (ADS)

    Valiev, U. V.; Gruber, J. B.; Rakhimov, Sh. A.

    2003-04-01

    Polarization spectra of optical absorption of the 4 f-4 f transition 6 H 15/2 → 6 F 3/2 in the rare-earth orthoaluminate DyAlO3 are theoretically and experimentally studied at the temperature T=78 K. It is shown that the nontrivial character of the anisotropy of the polarization absorption spectra at low temperatures can be explained by the J-J mixing of excited multiplets of the 4 f 9 configuration of Dy3+ ions in a low-symmetry crystal field of the orthoaluminate structure. The energy and wave functions of the Stark sublevels within the excited 6 F 5/2 multiplet in the 4 f 9 configuration of the Dy3+ rare-earth ion in the crystal field of C s symmetry are numerically calculated.

  6. Specific features of gas absorption in a rotating permeable porous medium

    NASA Astrophysics Data System (ADS)

    Bazhaikin, A. N.

    2014-01-01

    The absorption of gaseous ammonia (NH3), sulfur dioxide (SO2), and carbon dioxide (CO2) by water in a rotating cellular-porous disk medium has been experimentally studied. Data on the degree of air cleaning from these impurities are obtained, which are indicative of an anomalously high solubility (exceeding equilibrium values) of indicated gases in water under conditions studied. The results show the possibility of creating effective absorbers for air cleaning from gaseous impurities.

  7. Cryptography based on the absorption/emission features of multicolor semiconductor nanocrystal quantum dots

    NASA Astrophysics Data System (ADS)

    Zhou, Ming; Chang, Shoude; Grover, Chander P.

    2004-06-01

    Further to the optical coding based on fluorescent semiconductor quantum dots (QDs), a concept of using mixtures of multiple single-color QDs for creating highly secret cryptograms based on their absorption/emission properties was demonstrated. The key to readout of the optical codes is a group of excitation lights with the predetermined wavelengths programmed in a secret manner. The cryptograms can be printed on the surfaces of different objects such as valuable documents for security purposes.

  8. Features of Pc5 pulsations in the geomagnetic field, auroral luminosity, and Riometer absorption

    NASA Astrophysics Data System (ADS)

    Belakhovsky, V. B.; Pilipenko, V. A.; Samsonov, S. N.; Lorentsen, D.

    2016-01-01

    Simultaneous morning Pc5 pulsations ( f ~ 3-5 mHz) in the geomagnetic field, aurora intensities (in the 557.7 and 630.0 nm oxygen emissions and the 471.0 nm nitrogen emission), and riometer absorption, were studied based on the CARISMA, CANMOS, and NORSTAR network data for the event of January 1, 2000. According to the GOES-8 satellite observations, these Pc5 geomagnetic pulsations are observed as incompressible Alfvén waves with toroidal polarization in the magnetosphere. Although the Pc5 pulsation frequencies in auroras, the geomagnetic field, and riometer absorption are close to one another, stable phase relationships are not observed between them. Far from all trains of geomagnetic Pc5 pulsations are accompanied by corresponding auroral pulsations; consequently, geomagnetic pulsations are primary with respect to auroral pulsations. Both geomagnetic and auroral pulsations propagate poleward, and the frequency decreases with increasing geomagnetic latitude. When auroral Pc5 pulsations appear, the ratio of the 557.7/630.0 nm emission intensity sharply increases, which indicates that auroral pulsations result from not simply modulated particle precipitation but also an additional periodic acceleration of auroral electrons by the wave field. A high correlation is not observed between Pc5 pulsations in auroras and the riometer absorption, which indicates that these pulsations have a common source but different generation mechanisms. Auroral luminosity modulation is supposedly related to the interaction between Alfvén waves and the region with the field-aligned potential drop above the auroral ionosphere, and riometer absorption modulation is caused by the scattering of energetic electrons by VLF noise pulsations.

  9. Form drag in rivers due to small-scale natural topographic features: 1. Regular sequences

    USGS Publications Warehouse

    Kean, J.W.; Smith, J.D.

    2006-01-01

    Small-scale topographic features are commonly found on the boundaries of natural rivers, streams, and floodplains. A simple method for determining the form drag on these features is presented, and the results of this model are compared to laboratory measurements. The roughness elements are modeled as Gaussian-shaped features defined in terms of three parameters: a protrusion height, H; a streamwise length scale, ??; and a spacing between crests, ??. This shape is shown to be a good approximation to a wide variety of natural topographic bank features. The form drag on an individual roughness element embedded in a series of identical elements is determined using the drag coefficient of the individual element and a reference velocity that includes the effects of roughness elements further upstream. In addition to calculating the drag on each element, the model determines the spatially averaged total stress, skin friction stress, and roughness height of the boundary. The effects of bank roughness on patterns of velocity and boundary shear stress are determined by combining the form drag model with a channel flow model. The combined model shows that drag on small-scale topographic features substantially alters the near-bank flow field. These methods can be used to improve predictions of flow resistance in rivers and to form the basis for fully predictive (no empirically adjusted parameters) channel flow models. They also provide a foundation for calculating the near-bank boundary shear stress fields necessary for determining rates of sediment transport and lateral erosion.

  10. Dipping in CygnusX-2 in a multi-wavelength campaign due to absorption of extended ADC emission

    NASA Astrophysics Data System (ADS)

    Bałucińska-Church, M.; Schulz, N. S.; Wilms, J.; Gibiec, A.; Hanke, M.; Spencer, R. E.; Rushton, A.; Church, M. J.

    2011-06-01

    We report results of one-day simultaneous multiwavelength observations of CygnusX-2 using XMM, Chandra, the European VLBI Network and the XMM Optical Monitor. During the observations, the source did not exhibit Z-track movement, but remained in the vicinity of the soft apex. It was in a radio quiescent/quiet state of <150 μJy. Strong dip events were seen as 25% reductions in X-ray intensity. The use of broadband CCD spectra in combination with narrow-band grating spectra has now demonstrated for the first time that these dipping events in CygnusX-2 are caused by absorption in cool material in quite a unique way. In the band 0.2 - 10 keV, dipping appears to be due to progressive covering of the Comptonized emission of an extended accretion disk corona, the covering factor rising to 40% in deep dipping with an associated column density of 3 × 1023 atom cm-2. Remarkably, the blackbody emission of the neutron star is not affected by these dips, in strong contrast with observations of typical low mass X-ray binary dipping sources. The Chandra and XMM gratings directly measure the optical depths in absorption edges such as Ne K, Fe L, and O K and a comparison of the optical depths in the edges of non-dip and dip data reveals no increase of optical depth during dipping even though the continuum emission sharply decreases. Based on these findings, at orbital phase 0.35, we propose that dipping in this observation is caused by absorption in the outer disk by structures located opposite to the impact bulge of the accretion stream. With an inclination angle >60° these structures can still cover large parts of the extended ADC, without absorbing emission from the central neutral star.

  11. Calculations of Solar Shortwave Heating Rates due to Black Carbon and Ozone Absorption Using in Situ Measurements

    NASA Technical Reports Server (NTRS)

    Gao, R. S.; Hall, S. R.; Swartz, W. H.; Spackman, J. R.; Watts, L. A.; Fahey, D. W.; Aikin, K. C.; Shetter, R. E.; Bui, T. P.

    2008-01-01

    Results for the solar heating rates in ambient air due to absorption by black-carbon (BC) containing particles and ozone are presented as calculated from airborne observations made in the tropical tropopause layer (TTL) in January-February 2006. The method uses airborne in situ observations of BC particles, ozone and actinic flux. Total BC mass is obtained along the flight track by summing the masses of individually detected BC particles in the range 90 to 600-nm volume-equivalent diameter, which includes most of the BC mass. Ozone mixing ratios and upwelling and partial downwelling solar actinic fluxes were measured concurrently with BC mass. Two estimates used for the BC wavelength-dependent absorption cross section yielded similar heating rates. For mean altitudes of 16.5, 17.5, and 18.5 km (0.5 km) in the tropics, average BC heating rates were near 0.0002 K/d. Observed BC coatings on individual particles approximately double derived BC heating rates. Ozone heating rates exceeded BC heating rates by approximately a factor of 100 on average and at least a factor of 4, suggesting that BC heating rates in this region are negligible in comparison.

  12. Changes in the halo formation rates due to features in the primordial spectrum

    SciTech Connect

    Hazra, Dhiraj Kumar

    2013-03-01

    Features in the primordial scalar power spectrum provide a possible roadway to describe the outliers at the low multipoles in the WMAP data. Apart from the CMB angular power spectrum, these features can also alter the matter power spectrum and, thereby, the formation of the large scale structure. Carrying out a complete numerical analysis, we investigate the effects of primordial features on the formation rates of the halos. We consider a few different inflationary models that lead to features in the scalar power spectrum and an improved fit to the CMB data, and analyze the corresponding imprints on the formation of halos. Performing a Markov Chain Monte Carlo analysis with the WMAP seven year data and the SDSS halo power spectrum from LRG DR7 for the models of our interest, we arrive at the parameter space of the models allowed by the data. We illustrate that, inflationary potentials, such as the quadratic potential with sinusoidal modulations and the axion monodromy model, which generate certain repeated, oscillatory features in the inflationary perturbation spectrum, do not induce a substantial difference in the number density of halos at their best fit values, when compared with, say, a nearly scale invariant spectrum as is generated by the standard quadratic potential. However, we find that the number density and the formation rates of halos change by about 13–22% for halo masses ranging over 10{sup 4}–10{sup 14} M{sub s}un, for potential parameters that lie within 2-σ around the best fit values arrived at from the aforesaid joint constraints. We briefly discuss the implications of our results.

  13. The Role of Polycyclic Aromatic Hydrocarbons in Dense Cloud Absorption Features: The Last Major Unanswered Question in Interstellar Ice Spectroscopy

    NASA Astrophysics Data System (ADS)

    Chiar, Jean

    Interstellar dust plays a vital role in the star formation process and the eventual formation of planetary systems including our own. Ice mantles are an important component of the dust: reactions involving simple ices can create more complex (and astrobiologically interesting) molecules, and ices sublimated back into the gas phase influence the gas- phase chemistry. Although polycyclic aromatic hydrocarbons (PAHs) are commonly thought to be very abundant interstellar species and, as such, are likely to be important components of interstellar ices, their contribution to the infrared spectra and chemistry of ices in dense molecular clouds is an open question. This program makes extensive use of three major NASA-funded databases: the Spitzer archive, the 2MASS archive, and the NASA Ames PAH database in order to answer the last major unanswered question in interstellar ice spectroscopy: what role do PAHs play in contributing to unidentified absorption features observed in dense cloud spectra. PAHs are observed to be present and abundant in nearly all phases of the galactic and extragalactic interstellar medium. The evidence for the ubiquity of interstellar PAHs is the widespread well-known family of prominent emission bands at 3.28, 6.2, 7.7, 8.6, and 11.2 micron. To date, these PAH bands have been most easily detected in regions where individual gas phase PAH molecules (neutrals and ions) become highly vibrationally excited by the ambient radiation field. While PAHs and closely related aromatic materials should be present throughout dense interstellar regions, PAH emission is quenched in cold dark dense clouds. Also, in these regions, most PAHs should efficiently condense out onto dust grains, either as "pure" solids or as "guest molecules" in icy grain mantles, much as is the case for most other interstellar molecules. Thus, in dense molecular clouds, condensed PAHs will give rise to IR absorption bands rather than emission features. While PAH absorption has been

  14. Titan aerosol analog absorption features produced from aromatics in the far infrared

    NASA Astrophysics Data System (ADS)

    Sebree, Joshua A.; Trainer, Melissa G.; Loeffler, Mark J.; Anderson, Carrie M.

    2014-07-01

    We present results on the formation of Titan aerosol analogs produced via far-UV irradiation of five aromatic precursors: benzene, naphthalene, pyridine, quinoline and isoquinoline. This is the first reported evidence of far-IR emission features observed below 200 cm-1 in laboratory-created Titan aerosols. These laboratory studies were motivated by recent analyses of Cassini Composite Infrared Spectrometer (CIRS) spectra that show a broad aerosol emission feature in the far-IR spectral region centered near 140 cm-1, which is unique to Titan’s photochemically-produced aerosol (Anderson, C.M., Samuelson, R.E. [2011]. Icarus 212, 762-778). We find that all three of the aerosol analogs formed from nitrogen-containing aromatics have similar broad emission features near that of the observed CIRS far-IR aerosol spectral feature. In addition, the inclusion of 1.5% methane to that of trace amounts of benzene also gives rise to an aerosol with a weak far-IR emission feature located below 200 cm-1.

  15. Method and apparatus for simulating atomospheric absorption of solar energy due to water vapor and CO.sub.2

    DOEpatents

    Sopori, Bhushan L.

    1995-01-01

    A method and apparatus for improving the accuracy of the simulation of sunlight reaching the earth's surface includes a relatively small heated chamber having an optical inlet and an optical outlet, the chamber having a cavity that can be filled with a heated stream of CO.sub.2 and water vapor. A simulated beam comprising infrared and near infrared light can be directed through the chamber cavity containing the CO.sub.2 and water vapor, whereby the spectral characteristics of the beam are altered so that the output beam from the chamber contains wavelength bands that accurately replicate atmospheric absorption of solar energy due to atmospheric CO.sub.2 and moisture.

  16. Method and apparatus for simulating atmospheric absorption of solar energy due to water vapor and CO{sub 2}

    DOEpatents

    Sopori, B.L.

    1995-06-20

    A method and apparatus for improving the accuracy of the simulation of sunlight reaching the earth`s surface includes a relatively small heated chamber having an optical inlet and an optical outlet, the chamber having a cavity that can be filled with a heated stream of CO{sub 2} and water vapor. A simulated beam comprising infrared and near infrared light can be directed through the chamber cavity containing the CO{sub 2} and water vapor, whereby the spectral characteristics of the beam are altered so that the output beam from the chamber contains wavelength bands that accurately replicate atmospheric absorption of solar energy due to atmospheric CO{sub 2} and moisture. 8 figs.

  17. Mapping vegetation types with the multiple spectral feature mapping algorithm in both emission and absorption

    NASA Technical Reports Server (NTRS)

    Clark, Roger N.; Swayze, Gregg A.; Koch, Christopher; Ager, Cathy

    1992-01-01

    Vegetation covers a large portion of the Earth's land surface. Remotely sensing quantitative information from vegetation has proven difficult because in a broad sense, all vegetation is similar from a chemical viewpoint, and most healthy plants are green. Plant species are generally characterized by the leaf and flower or fruit morphology, not by remote sensing spectral signatures. But to the human eye, many plants show varying shades of green, so there is direct evidence for spectral differences between plant types. Quantifying these changes in a predictable manner has not been easy. The Clark spectral features mapping algorithm was applied to mapping spectral features in vegetation species.

  18. Automated extraction of absorption features from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and Geophysical and Environmental Research Imaging Spectrometer (GERIS) data

    NASA Technical Reports Server (NTRS)

    Kruse, Fred A.; Calvin, Wendy M.; Seznec, Olivier

    1988-01-01

    Automated techniques were developed for the extraction and characterization of absorption features from reflectance spectra. The absorption feature extraction algorithms were successfully tested on laboratory, field, and aircraft imaging spectrometer data. A suite of laboratory spectra of the most common minerals was analyzed and absorption band characteristics tabulated. A prototype expert system was designed, implemented, and successfully tested to allow identification of minerals based on the extracted absorption band characteristics. AVIRIS spectra for a site in the northern Grapevine Mountains, Nevada, have been characterized and the minerals sericite (fine grained muscovite) and dolomite were identified. The minerals kaolinite, alunite, and buddingtonite were identified and mapped for a site at Cuprite, Nevada, using the feature extraction algorithms on the new Geophysical and Environmental Research 64 channel imaging spectrometer (GERIS) data. The feature extraction routines (written in FORTRAN and C) were interfaced to the expert system (written in PROLOG) to allow both efficient processing of numerical data and logical spectrum analysis.

  19. THE 217.5 nm BAND, INFRARED ABSORPTION, AND INFRARED EMISSION FEATURES IN HYDROGENATED AMORPHOUS CARBON NANOPARTICLES

    SciTech Connect

    Duley, W. W.; Hu, Anming E-mail: a2hu@uwaterloo.ca

    2012-12-20

    We report on the preparation of hydrogenated amorphous carbon nanoparticles whose spectral characteristics include an absorption band at 217.5 nm with the profile and characteristics of the interstellar 217.5 nm feature. Vibrational spectra of these particles also contain the features commonly observed in absorption and emission from dust in the diffuse interstellar medium. These materials are produced under ''slow'' deposition conditions by minimizing the flux of incident carbon atoms and by reducing surface mobility. The initial chemistry leads to the formation of carbon chains, together with a limited range of small aromatic ring molecules, and eventually results in carbon nanoparticles having an sp {sup 2}/sp {sup 3} ratio Almost-Equal-To 0.4. Spectroscopic analysis of particle composition indicates that naphthalene and naphthalene derivatives are important constituents of this material. We suggest that carbon nanoparticles with similar composition are responsible for the appearance of the interstellar 217.5 nm band and outline how these particles can form in situ under diffuse cloud conditions by deposition of carbon on the surface of silicate grains. Spectral data from carbon nanoparticles formed under these conditions accurately reproduce IR emission spectra from a number of Galactic sources. We provide the first detailed fits to observational spectra of Type A and B emission sources based entirely on measured spectra of a carbonaceous material that can be produced in the laboratory.

  20. Improvement in the photocurrent collection due to enhanced absorption of light by synthesizing staggered layers of silver nanoclusters in silicon

    SciTech Connect

    Dhoubhadel, Mangal S.; Lakshantha, Wickramaarachchige J.; Rout, Bibhudutta; McDaniel, Floyd D.; Lightbourne, Sherard; D’Souza, Francis

    2015-07-23

    The quest for increased efficiency of solar cells has driven the research in synthesizing photovoltaic cells involving Si based materials. The efficiency of solar cells involving crystalline Si is stalled around 25% for the last decade. Recently Shi et al. had shown that light trapping can be enhanced by fabricating double layers of Ag nanoparticles in silicon based materials. The light trapping is critically important in a photo devices such as solar cells in order to increase light absorption and efficiency. In the present work, we report enhancement in the absorption of light in Ag ion implanted Si substrates. Multiple low energies Ag ions, ranging from ∼80 keV to ∼30 keV, with different fluences ranging from ∼1 × 10{sup 16} to ∼1 × 10{sup 17} atoms/cm{sup 2} were sequentially implanted into commercially available Si (100) substrates followed by post-thermal annealing to create different sizes of Ag nanoclusters (NC) at different depths in the top 100 nm of the Si. The absorbance of light is increased in Ag implanted Si with a significant increase in the current collection in I-V (current-voltage) photo switching measurements. The experimental photovoltaic cells fabricated with the Ag-implanted Si samples were optically characterized under AM (air mass) 1.5 solar radiation conditions (∼1.0 kW/m{sup 2}). An enhancement in the charge collection were measured in the annealed samples, where prominent Ag NCs were formed in the Si matrix compared to the as-implanted samples with amorphous layers. We believe the enhancement of the photo-current density from the samples with Ag NC is due to the improvement of efficiency of charge collection of e{sup −}-h{sup +} pairs produced by the incident light.

  1. Modeling of geomagnetic activity due to passage of different structures and features of high speed streams

    NASA Astrophysics Data System (ADS)

    Mustajab, Fainana

    2016-07-01

    The modeling of terrestrial environment and relative geoeffectiveness due to high speed streams of different type and also compare their geoeffectiveness due to fine structures associated with streams, for example i) streams with different speed, ii) streams with different durations, iii) streams from different solar source and iv) associated fine structures. We also observed high speed streams during 1996 to 2011, and divided them into convenient groups based on their i) speed, ii) durations, iii) solar sources and iv) Dst groups. Performed them method of superposed-epoch analysis and other some statistical-analysis and correlation analysis between geomagnetic index Dst and plasma/field parameters during for both main phase and recovery phase. Streams having the passage duration ranging from 4.5 days to 10.5 days is 59% while other groups, having passage duration <4.5 days and > 10.5 days, contribute only near about 13%. When we observe group according to speed of streams, 30% of high speed streams are having the speed >650km/s and other groups are near about equally distributed in the range 400km/s to 650km/s. Out of 575 high speed streams, 45% streams are caused by single coronal hole, 20% due to multiple coronal hole, 24% by compound i.e: due to coronal hole and coronal mass ejections and only 10% from coronal mass ejections. The streams which are responsible for quiet, weak, moderate storms are nearly equal and only 12% streams cause severe storms. Dst gives best correlation with V(km/s) and BVres to the power 2 (x10res to the power 6) for over all storm time. B(nT) and BV(x10res to the power 3) represent good correlation with Dst during recovery phase duration for the speed groups. I observed the percentage of quiet storms decreases with increasing speed of streams. Near about equal percentage of weak storm are observed in each set of speed of stream. 17% moderate storms are found to contribute for the speed range 400-550km/s and ≈33% contribution is

  2. Clinical & pathological features of acute toxicity due to Cassia occidentalis in vertebrates.

    PubMed

    Vashishtha, V M; John, T J; Kumar, Amod

    2009-07-01

    Cassia occidentalis is an annual shrub found in many countries including India. Although bovines and ovines do not eat it, parts of the plant are used in some traditional herbal medicines. Several animal studies have documented that fresh or dried beans are toxic. Ingestion of large amounts by grazing animals has caused serious illness and death. The toxic effects in large animals, rodents and chicken are on skeletal muscles, liver, kidney and heart. The predominant systems involved depend upon the animal species and the dose of the beans consumed. Brain functions are often affected. Gross lesions at necropsy consist of necrosis of skeletal muscle fibres and hepatic centrilobular necrosis; renal tubular necrosis is less frequent. Muscle and liver cell necrosis is reflected in biochemical abnormalities. The median lethal dose (LD(50)) is 1 g/kg for mice and rats. Toxicity is attributed to various anthraquinones and their derivatives and alkaloids, but the specific toxins have not been identified. Data on human toxicity are extremely scarce. This review summarizes information available on Cassia toxicity in animals and compares it with toxic features reported in children. The clinical spectrum and histopathology of C. occidentalis poisoning in children resemble those of animal toxicity, affecting mainly hepatic, skeletal muscle and brain tissues. The case-fatality rate in acute severe poisoning is 75-80 per cent in children. PMID:19700797

  3. Host cell death due to enteropathogenic Escherichia coli has features of apoptosis.

    PubMed

    Crane, J K; Majumdar, S; Pickhardt, D F

    1999-05-01

    Enteropathogenic Escherichia coli (EPEC) is a cause of prolonged watery diarrhea in children in developing countries. The ability of EPEC to kill host cells was investigated in vitro in assays using two human cultured cell lines, HeLa (cervical) and T84 (colonic). EPEC killed epithelial cells as assessed by permeability to the vital dyes trypan blue and propidium iodide. In addition, EPEC triggered changes in the host cell, suggesting apoptosis as the mode of death; such changes included early expression of phosphatidylserine on the host cell surface and internucleosomal cleavage of host cell DNA. Genistein, an inhibitor of tyrosine kinases, and wortmannin, an inhibitor of host phosphatidylinositol 3-kinase, markedly increased EPEC-induced cell death and enhanced the features of apoptosis. EPEC-induced cell death was contact dependent and required adherence of live bacteria to the host cell. A quantitative assay for EPEC-induced cell death was developed by using the propidium iodide uptake method adapted to a fluorescence plate reader. With EPEC, the rate and extent of host cell death were less that what has been reported for Salmonella, Shigella, and Yersinia, three other genera of enteric bacteria known to cause apoptosis. However, rapid apoptosis of the host cell may not favor the pathogenic strategy of EPEC, a mucosa-adhering, noninvasive pathogen. PMID:10225923

  4. Comparison of facial features of DiGeorge syndrome (DGS) due to deletion 10p13-10pter with DGS due to 22q11 deletion

    SciTech Connect

    Goodship, J.; Lynch, S.; Brown, J.

    1994-09-01

    DiGeorge syndrome (DGS) is a congenital anomaly consisting of cardiac defects, aplasia or hypoplasia of the thymus and parathroid glands, and dysmorphic facial features. The majority of DGS cases have a submicroscopic deletion within chromosome 22q11. However there have been a number of reports of DGS in association with other chromosomal abnormalities including four cases with chromosome 10p deletions. We describe a further 10p deletion case and suggest that the facial features in children with DGS due to deletions of 10p are different from those associated with chromosome 22 deletions. The propositus was born at 39 weeks gestation to unrelated caucasian parents, birth weight 2580g (10th centile) and was noted to be dysmorphic and cyanosed shortly after birth. The main dysmorphic facial features were a broad nasal bridge with very short palpebral fissures. Echocardiography revealed a large subsortic VSD and overriding aorta. She had a low ionised calcium and low parathroid hormone level. T cell subsets and PHA response were normal. Abdominal ultrasound showed duplex kidneys and on further investigation she was found to have reflux and raised plasma creatinine. She had an anteriorly placed anus. Her karyotype was 46,XX,-10,+der(10)t(3;10)(p23;p13)mat. The dysmorphic facial features in this baby are strikingly similar to those noted by Bridgeman and Butler in child with DGS as the result of a 10p deletion and distinct from the face seen in children with DiGeorge syndrome resulting from interstitial chromosome 22 deletions.

  5. Far-IR Absorption Features of Titan Aerosol Analogs Produced from Aromatic Precursors

    NASA Astrophysics Data System (ADS)

    Sebree, Joshua; Trainer, M. G.; Anderson, C. M.; Loeffler, M. J.

    2012-10-01

    The arrival of the Cassini spacecraft in orbit around Saturn has led to the discovery of benzene (C6H6) at ppm levels, as well as large positive ions in Titan’s atmosphere, tentatively identified as polycyclic aromatic hydrocarbons (PAHs).[1] The presence of aromatic molecules, which are photolytically active in the ultraviolet, may be an important part of the formation of aerosol particles in Titan’s haze layers, even at these low concentrations. To date, there have been no laboratory experiments in the literature exploring this area of study. The analysis of data from the Composite Infrared Spectrometer (CIRS) on-board Cassini has recently uncovered a broad emission feature centered at 140 cm-1 in the far-IR that is unique to the aerosol layers of Titan’s atmosphere.[2] Current optical constants from laboratory-generated aerosol analogs have been unable to reproduce this feature.[3,4] From the broadness of this feature, we speculate that the emission is a blended composite of low-energy vibrations of large molecules such as PAHs and their nitrogen containing counterparts, polycyclic aromatic nitrogen heterocycles (PANHs). We hypothesize that the inclusion of trace amounts of aromatic precursors will aid in the production of these large structures in the laboratory-generated aerosols. In this study, we perform UV irradiation of several aromatic precursors, both with and without nitrogen heteroatoms, to understand their influence on the observable characteristics of the aerosol. Measured optical and chemical properties will be compared to those formed from CH4/N2 mixtures [5,6] as well as to those from Cassini observations. [1] Waite, J. H., et al. (2007) Science 316 870-875. [2] Anderson, C.M, et al. (2011) Icarus 212 762-778. [3] Khare, B.N., et al. (1984) Icarus 60 127-137. [4] Imanaka, H., et al. (2012) Icarus 218 247-261. [5] Trainer, M.G., et al. (2006) PNAS 103 18035-18042. [6] Trainer, M.G., et al. (2012) Astrobiology 12 315-326.

  6. X-RAY EMISSION AND ABSORPTION FEATURES DURING AN ENERGETIC THERMONUCLEAR X-RAY BURST FROM IGR J17062-6143

    SciTech Connect

    Degenaar, N.; Miller, J. M.; Wijnands, R.; Altamirano, D.; Fabian, A. C.

    2013-04-20

    Type-I X-ray bursts are thermonuclear explosions occurring in the surface layers of accreting neutron stars. These events are powerful probes of the physics of neutron stars and their surrounding accretion flow. We analyze a very energetic type-I X-ray burst from the neutron star low-mass X-ray binary IGR J17062-6143 that was detected with Swift on 2012 June 25. The light curve of the {approx_equal}18 minute long X-ray burst tail shows an episode of {approx_equal}10 minutes during which the intensity is strongly fluctuating by a factor of {approx_equal}3 above and below the underlying decay trend on a timescale of seconds. The X-ray spectrum reveals a highly significant emission line around {approx_equal}1 keV, which can be interpreted as an Fe-L shell line caused by the irradiation of cold gas. We also detect significant absorption lines and edges in the Fe-K band, which are strongly suggestive of the presence of hot, highly ionized gas along the line of sight. None of these features are present in the persistent X-ray spectrum of the source. The timescale of the strong intensity variations, the velocity width of the Fe-L emission line (assuming Keplerian motion), and photoionization modeling of the Fe-K absorption features each independently point to gas at a radius of {approx_equal} 10{sup 3} km as the source of these features. The unusual X-ray light curve and spectral properties could have plausibly been caused by a disruption of the accretion disk due to the super-Eddington fluxes reached during the X-ray burst.

  7. Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+641. 2.5

    NASA Technical Reports Server (NTRS)

    Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle, W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.; Kaiser, M. E.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We present a moderate-resolution (approximately 20 km/s) spectrum of the broad-absorption line QSO PG 1351+64 between 915-1180 angstroms, obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). Additional low-resolution spectra at longer wavelengths were also obtained with the Hubble Space Telescope (HST) and ground-based telescopes. Broad absorption is present on the blue wings of C III lambda977, Ly-beta, O VI lambda-lambda-1032,1038, Ly-alpha, N V lambda-lambda-1238,1242, Si IV lambda-lambda-1393,1402, and C IV lambda-lambda-1548,1450. The absorption profile can be fitted with five components at velocities of approximately -780, -1049, -1629, -1833, and -3054 km/s with respect to the emission-line redshift of z = 0.088. All the absorption components cover a large fraction of the continuum source as well as the broad-line region. The O VI emission feature is very weak, and the O VI/Ly-alpha flux ratio is 0.08, one of the lowest among low-redshift active galaxies and QSOs. The ultraviolet continuum shows a significant change in slope near 1050 angstroms in the restframe. The steeper continuum shortward of the Lyman limit extrapolates well to the observed weak X-ray flux level. The absorbers' properties are similar to those of high-redshift broad absorption-line QSOs. The derived total column density of the UV absorbers is on the order of 10(exp 21)/s, unlikely to produce significant opacity above 1 keV in the X-ray. Unless there is a separate, high-ionization X-ray absorber, the QSO's weak X-ray flux may be intrinsic. The ionization level of the absorbing components is comparable to that anticipated in the broad-line region, therefore the absorbers may be related to broad-line clouds along the line of sight.

  8. Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+64. 3.1

    NASA Technical Reports Server (NTRS)

    Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle, W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.; Kaiser, M. E.; Fisher, R. (Technical Monitor)

    2001-01-01

    We present a moderate-resolution (approximately 20 km s(exp -1) spectrum of the mini broad absorption line QSO PG 1351+64 between 915-1180 A, obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). Additional low-resolution spectra at longer wavelengths were also obtained with the Hubble Space Telescope (HST) and ground-based telescopes. Broad absorption is present on the blue wings of C III (lambda)977, Ly(beta), O VI (lambda)(lambda)1032,1038, Ly(alpha), N V (lambda)(lambda)1238,1242, Si IV (lambda)(lambda)1393,1402, and C IV (lambda)(lambda)1548,1450. The absorption profile can be fitted with five components at velocities of approximately -780, -1049, -1629, -1833, and -3054 km s(exp -1) with respect to the emission-line redshift of z = 0.088. All the absorption components cover a large fraction of the continuum source as well as the broad-line region. The O VI emission feature is very weak, and the O VI/Ly(alpha) flux ratio is 0.08, one of the lowest among low-redshift active galaxies and QSOs. The UV (ultraviolet) continuum shows a significant change in slope near 1050 A in the restframe. The steeper continuum shortward of the Lyman limit extrapolates well to the observed weak X-ray flux level. The absorbers' properties are similar to those of high-redshift broad absorption-line QSOs. The derived total column density of the UV absorbers is on the order of 10(exp 21) cm(exp -2), unlikely to produce significant opacity above 1 keV in the X-ray. Unless there is a separate, high-ionization X-ray absorber, the QSO's weak X-ray flux may be intrinsic. The ionization level of the absorbing components is comparable to that anticipated in the broad-line region, therefore the absorbers may be related to broad-line clouds along the line of sight.

  9. Deterioration of Pracana Dam due to ASR. Main features and repair works

    SciTech Connect

    Matos, D.S.; Camelo, S.; Silva, H.S.; Pinho, J.S.

    1995-12-31

    Some of the Portuguese concrete dams show evidences of ASR. In majority the phenomena is still benign. However, in a few cases some significant deterioration of ASR type have malfunctions arose. In such cases deteriorations of ASR type have been detected while in the others the ASSR type prevail, depending on the type of aggregate. The paper reports the most important case of ASR in Portuguese concrete dams. Pracana dam is a buttress structures built in 1948-51, being the aggregates predominantly of quartzitic and metapellitic nature. Subsequently to the intense fracturing due to a quick concrete cooling during the first filling of the reservoir, high levels of expansion rates had been detected by means of monitoring system. After 8 years emptied reservoir, rehabilitation works took place in 1991-92 aiming at the concrete mass regeneration and the installation of an upstream face membrane, the improvement of spillway capacity and of the foundation performances. The behaviour of the dam as well as the performed tests (petrographic, mechanic, ultrasonic and expansibility ones) and repair works are described in the paper.

  10. Spectroscopic determination of leaf biochemistry using band-depth analysis of absorption features and stepwise multiple linear regression

    USGS Publications Warehouse

    Kokaly, R.F.; Clark, R.N.

    1999-01-01

    We develop a new method for estimating the biochemistry of plant material using spectroscopy. Normalized band depths calculated from the continuum-removed reflectance spectra of dried and ground leaves were used to estimate their concentrations of nitrogen, lignin, and cellulose. Stepwise multiple linear regression was used to select wavelengths in the broad absorption features centered at 1.73 ??m, 2.10 ??m, and 2.30 ??m that were highly correlated with the chemistry of samples from eastern U.S. forests. Band depths of absorption features at these wavelengths were found to also be highly correlated with the chemistry of four other sites. A subset of data from the eastern U.S. forest sites was used to derive linear equations that were applied to the remaining data to successfully estimate their nitrogen, lignin, and cellulose concentrations. Correlations were highest for nitrogen (R2 from 0.75 to 0.94). The consistent results indicate the possibility of establishing a single equation capable of estimating the chemical concentrations in a wide variety of species from the reflectance spectra of dried leaves. The extension of this method to remote sensing was investigated. The effects of leaf water content, sensor signal-to-noise and bandpass, atmospheric effects, and background soil exposure were examined. Leaf water was found to be the greatest challenge to extending this empirical method to the analysis of fresh whole leaves and complete vegetation canopies. The influence of leaf water on reflectance spectra must be removed to within 10%. Other effects were reduced by continuum removal and normalization of band depths. If the effects of leaf water can be compensated for, it might be possible to extend this method to remote sensing data acquired by imaging spectrometers to give estimates of nitrogen, lignin, and cellulose concentrations over large areas for use in ecosystem studies.We develop a new method for estimating the biochemistry of plant material using

  11. Detection of narrow C 4 and Si 4 absorption features in spectra of stars within 200 pc f the Sun

    NASA Technical Reports Server (NTRS)

    Molaro, P.; Beckman, J. E.; Franco, M.; Morossi, C.; Ramella, M.

    1984-01-01

    Detection of narrow (Beta lambda 0.5 A) absorption features in C 4 at lambda lambda 1548 and 1550 have been made in the spectra of 4 late B dwarfs within 200 pc of the Sun; the Si4 doublet at lambda lambda 1393 and 1403 shows up in two of them. It is argued that it is difficult to account for the strengths, widths, shapes, and C IV/Si IV ratios in terms consistent with a circumstellar origin except possibly for an asymmetric C IV component in one star (HD 185037). The most probable source is semi-torrid gas in the 50,000 K range forming the interfaces between cooler H 1 clouds and the ambient medium at coronal temperatures. Late B rapid rotators are used for local interstellar medium probing of this kind.

  12. New narrow infrared absorption features in the spectrum of Io between 3600 and 3100 cm (2.8-3.2 micrometers)

    NASA Technical Reports Server (NTRS)

    Sandford, Scott A.; Geballe, Thomas R.; Salama, Farid; Goorvitch, David

    1994-01-01

    We report the discovery of a series of infrared absorption bands between 3600 and 3100/cm (2.8-3.2 micrometers) in the spectrum of Io. Individual narrow bands are detected at 3553, 3514.5, 3438, 3423, 3411.5, and 3401/cm (2.815, 2.845, 2.909, 2.921, 2.931, and 2.940 micrometers, respectively). The positions and relative strengths of these bands, and the difference of their absolute strengths between the leading and trailing faces of Io, indicate that they are due to SO2. The band at 3438/cm (2.909 micrometers) could potentially have a contribution from an additional molecular species. The existence of these bands in the spectrum of Io indicates that a substantial fraction of the SO2 on Io must reside in transparent ices having relatively large crystal sizes. The decrease in the continuum observed at the high frequency ends of the spectra is probably due to the low frequency side of the recently detected, strong 3590/cm (2.79 micrometer) feature. This band is likely due to the combination of a moderately strong SO2 band and an additional absorption from another molecular species, perhaps H2O isolated in SO2 at low concentrations. A broad (FWHM approximately = 40-60/cm), weak band is seen near 3160/cm (3.16 micrometers) and is consistent with the presence of small quantities of H2O isolated in SO2-rich ices. There is no evidence in the spectra for the presence of H2O vapor on Io. Thus, the spectra presented here neither provide unequivocal evidence for the presence of H2O on Io nor preclude it at the low concentrations suggested by past studies.

  13. Specific absorption rate variation in a brain phantom due to exposure by a 3G mobile phone: problems in dosimetry.

    PubMed

    Behari, J; Nirala, Jay Prakash

    2013-12-01

    A specific absorption rate (SAR) measurements system has been developed for compliance testing of personal mobile phone in a brain phantom material contained in a Perspex box. The volume of the box has been chosen corresponding to the volume of a small rat and illuminated by a 3G mobile phone frequency (1718.5 MHz), and the emitted radiation directed toward brain phantom .The induced fields in the phantom material are measured. Set up to lift the plane carrying the mobile phone is run by a pulley whose motion is controlled by a stepper motor. The platform is made to move at a pre-determined rate of 2 degrees per min limited up to 20 degrees. The measured data for induced fields in various locations are used to compute corresponding SAR values and inter comparison obtained. These data are also compared with those when the mobile phone is placed horizontally with respect to the position of the animal. The SAR data is also experimentally obtained by measuring a rise in temperature due to this mobile exposures and data compared with those obtained in the previous set. To seek a comparison with the safety criteria same set of measurements are performed in 10 g phantom material contained in a cubical box. These results are higher than those obtained with the knowledge of induced field measurements. It is concluded that SAR values are sensitive to the angular position of the moving platform and are well below the safety criteria prescribed for human exposure. The data are suggestive of having a fresh look to understand the mode of electromagnetic field -bio interaction. PMID:24579373

  14. Solar radiation absorption in the atmosphere due to water and ice clouds: Sensitivity experiments with plane-parallel clouds

    SciTech Connect

    Gautier, C.

    1995-09-01

    One cloud radiation issue that has been troublesome for several decades is the absorption of solar radiation by clouds. Many hypotheses have been proposed to explain the discrepancies between observations and modeling results. A good review of these often-competing hypotheses has been provided by Stephens and Tsay. They characterize the available hypotheses as failing into three categories: (1) those linked to cloud microphysical and consequent optical properties; (2) those linked to the geometry and heterogeneity of clouds; and (3) those linked to atmospheric absorption.Current modeling practice is seriously inconsistent with new observational inferences concerning absorption of solar radiation in the atmosphere. The author and her colleagues contend that an emphasis on R may, therefore, not be the optimal way of addressing the cloud solar absorption issue. 4 refs., 1 fig.

  15. TOWARD DETECTING THE 2175 A DUST FEATURE ASSOCIATED WITH STRONG HIGH-REDSHIFT Mg II ABSORPTION LINES

    SciTech Connect

    Jiang Peng; Zhou Hongyan; Wang Junxian; Wang Tinggui; Ge Jian

    2011-05-10

    We report detections of 39 2175 A dust extinction bump candidates associated with strong Mg II absorption lines at z{approx} 1-1.8 on quasar spectra in Sloan Digital Sky Survey (SDSS) DR3. These strong Mg II absorption line systems are detected among 2951 strong Mg II absorbers with a rest equivalent width W{sub r} {lambda}2796> 1.0 A at 1.0 < z < 1.86, which is part of a full sample of 7421 strong Mg II absorbers compiled by Prochter et al. The redshift range of the absorbers is chosen to allow the 2175 A extinction features to be completely covered within the SDSS spectrograph operation wavelength range. An upper limit of the background quasar emission redshift at z = 2.1 is set to prevent the Ly{alpha} forest lines from contaminating the sensitive spectral region for the 2175 A bump measurements. The FM90 parameterization is applied to model the optical/UV extinction curve in the rest frame of Mg II absorbers of the 2175 A bump candidates. The simulation technique developed by Jiang et al. is used to derive the statistical significance of the candidate 2175 A bumps. A total of 12 absorbers are detected with 2175 A bumps at a 5{sigma} level of statistical significance, 10 are detected at a 4{sigma} level, and 17 are detected at a 3{sigma} level. Most of the candidate bumps in this work are similar to the relatively weak 2175 A bumps observed in the Large Magellanic Cloud LMC2 supershell rather than the strong ones observed in the Milky Way. This sample has greatly increased the total number of 2175 A extinction bumps measured on SDSS quasar spectra. Follow-up observations may rule out some of the possible false detections and reveal the physical and chemical natures of 2175 A quasar absorbers.

  16. Radial Trends in IMF-sensitive Absorption Features in Two Early-type Galaxies: Evidence for Abundance-driven Gradients

    NASA Astrophysics Data System (ADS)

    McConnell, Nicholas J.; Lu, Jessica R.; Mann, Andrew W.

    2016-04-01

    Samples of early-type galaxies show a correlation between stellar velocity dispersion and the stellar initial mass function (IMF) as inferred from gravity-sensitive absorption lines in the galaxies’ central regions. To search for spatial variations in the IMF, we have observed two early-type galaxies with Keck/LRIS and measured radial gradients in the strengths of absorption features from 4000–5500 Å and 8000–10000 Å. We present spatially resolved measurements of the dwarf-sensitive spectral indices {Na} {{I}} (8190 Å) and Wing-Ford {{FeH}} (9915 Å), as well as indices for species of H, C2, CN, Mg, Ca, {{TiO}}, and Fe. Our measurements show a metallicity gradient in both objects, and Mg/Fe consistent with a shallow gradient in α-enhancement, matching widely observed trends for massive early-type galaxies. The {Na} {{I}} index and the CN1 index at 4160 Å exhibit significantly steeper gradients, with a break at r∼ 0.1 {r}{{eff}} (r∼ 300 pc). Inside this radius, {Na} {{I}} strength increases sharply toward the galaxy center, consistent with a rapid central rise in [Na/Fe]. In contrast, the ratio of the {{FeH}} to Fe index strength decreases toward the galaxy center. This behavior cannot be reproduced by a steepening IMF inside of 0.1 {r}{{eff}} if the IMF is a single power law. While gradients in the mass function above ∼ 0.4 {M}ȯ may occur, exceptional care is required to disentangle these IMF variations from the extreme variations in individual element abundances near the galaxies’ centers.

  17. A compilation of electronic transitions in the CO molecule and the interpretation of some puzzling interstellar absorption features

    NASA Astrophysics Data System (ADS)

    Morton, Donald C.; Noreau, Louis

    1994-11-01

    This compilation lists wavenumbers, wavelengths, and oscillator strengths for 1589 electronic transitions of (12)C(16)O, (13)C(16)O, (12)C(18)O, and (13)C(18)O between 1000 and 1545 A. These are the transitions from J double prime = 0 to 6 and v double prime = 0 of the ground term which are most likely to appear as interstellar absorption lines in spectra observed with the Hubble Space Telescope and other instruments in space. We include a derivation of the formulae relating transition probabilities, lifetimes, line strengths, and oscillator strengths for individual rovibronic transitions and whole bands. The compilation contains all the known spin-permitted bands A1Pi - X1Sigma+, B1Sigma+ - X1Sigma+, C1Sigma+ - X1Sigma+, E1Pi - X1Sigma+, and F1Sigma+ - X1Sigma+, as well as the spin-forbidden a'3Sigma+ - X1Sigma+, d3delta - X1Sigma+ and e3Sigma- - X1Sigma+ bands which are enhanced by perturbations of A1Pi on certain of their upper levels. Oscillator strengths are quoted for each rovibronic transition, taking account of the mixing of the triplet states with A1 Pi, v' = 0 to 6. A separate finding list orders the stronger transitions with J double prime less than or equal to 3 by wavelength. Comparison of the compiled data with existing UV observations of HD 27778, zeta Oph, and 20 Aql shows how the a' - X, d - X, and e - X bands that borrow oscillator strength from A - X can account for several puzzling absorption features. Finally, we include some suggestions for further study with spectrographs in the laboratory and in space.

  18. Spectroscopic Character and Spatial Distribution of Hydroxyl and Water Absorption Features Measured on the Lunar Surface by the Moon Mineralogy Mapper Imaging Spectrometer on Chandrayaan-1

    NASA Astrophysics Data System (ADS)

    Green, R. O.; Pieters, C. M.; Goswami, J.; Clark, R. N.; Annadurai, M.; Boardman, J. W.; Buratti, B. J.; Combe, J.; Dyar, M. D.; Head, J. W.; Hibbitts, C.; Hicks, M.; Isaacson, P.; Klima, R. L.; Kramer, G. Y.; Kumar, S.; Livo, K. E.; Lundeen, S.; Malaret, E.; McCord, T. B.; Mustard, J. F.; Nettles, J. W.; Petro, N. E.; Runyon, C. J.; Staid, M.; Sunshine, J. M.; Taylor, L. A.; Tompkins, S.; Varanasi, P.

    2009-12-01

    The Moon Mineralogy Mapper imaging spectrometer on Chandrayaan-1 has a broad spectral range from 430 to 3000 nm. By design, the range was specified to extend to 3000 nm to allow for possible detection of trace volatile compounds that possess absorption bands near 3000 nm. Soon after acquisition and calibration of a large fraction of the lunar surface in early February 2009, absorption features in the 2700 to 3000 nm region were detected over unexpectedly large regional areas. This extraordinary discovery has withstood extensive re-analysis and falsification efforts. We have concluded these absorption features are fundamentally present in the M3 measurements and are indicators of extensive hydroxyl and water-bearing materials occurring on the surface of the Moon. Based on current analyses, these absorption features appear strongest at high latitudes, but also occur in association with several fresh feldspathic craters. Interestingly, the distribution of these absorption features are not directly correlated with existing neutron spectrometer hydrogen abundance data for the sunlight surface. This may indicate that the formation and retention of hydroxyl and water is an active process largely restricted to the upper most surface. We present the detailed spectroscopic character of these absorption features in the 2700 to 3000 nm spectral region, including selected examples through all levels of measurement processing from raw data to calibrated apparent surface reflectance. In summary we show the measured strength and latitudinal distribution of the absorptions as well as selected localized occurrences in association with fresh feldspathic craters. The presence of hydroxyl and water bearing material over extensive regions of the lunar surface provides a new and unexpected source of volatiles. Options for harvesting these elements directly from the regolith may provide an alternate supply of volatiles for long term human exploration objectives.

  19. Variation of spectral properties of dielectric ionic crystal in the terahertz range due to the polariton absorption.

    PubMed

    Dzedolik, Igor V; Pereskokov, Vladislav

    2014-05-20

    The dispersion equations for polariton waves in dielectric ionic crystal with the absorption are obtained. The self-consistent solutions of the system of Maxwell electromagnetic field equations and the equations of motion of ions have been used. The elastic and absorption properties of the crystal are taken into account in the ion equations of motion. It is shown that the separated equations of motion for positive and negative ions allow obtaining all branches of phonon and polariton spectrum by the example of the ionic crystal of cubic symmetry at the terahertz range. It has been shown that the variation of absorption in the crystal leads to changing of the character of spectrum branch and the polariton velocities. PMID:24922221

  20. Use of calibration targets in the measurement of 2.22-micron mineral absorption features in Thematic Mapper data

    NASA Technical Reports Server (NTRS)

    Elvidge, Christopher D.

    1987-01-01

    A mineral absorption index (MAI) has been developed to separate leaf water and mineral absorption in the 2.22-micron Thematic Mapper band. The MAI uses three baselines to estimate and subtract the absorption attributable to vegetation. Digital number data from calibration targets devoid of vegetation are used to establish the positions of the baselines in Thematic Mapper data.

  1. Long-Term Sickness Absence Due to Mental Disorders Is Associated with Individual Features and Psychosocial Work Conditions

    PubMed Central

    da Silva-Junior, João Silvestre; Fischer, Frida Marina

    2014-01-01

    Aims Sickness absence is a socioeconomic global burden. In Brazil, mental disorders are the third leading cause of social security benefits payments. The aim of the present study was to compare factors associated with long-term sickness absence between workers who claimed social benefits due to mental disorders or by other causes. We investigated individual features and occupational characteristics. In addition, we evaluated psychosocial factors at work assessed by the Demand-Control-Support (DCS) and Effort-Reward Imbalance (ERI) models, and whether they were associated with long-term sickness absence due to mental disorders (LTSA-MD). Methods The present case-control study was conducted in São Paulo, Brazil. The sample (n = 385) included workers on sick leave for more than 15 days. Cases were the participants with disabling psychiatric illnesses, and controls were the ones with other disabling diseases. Interviews were conducted to assess individual features (sociodemographic data, health habits/lifestyle, health conditions) and occupational characteristics. The participants' perception of exposure to dimensions of the DCS and ERI models was also recorded. Multiple logistic regressions were performed to evaluate the association between independent variables and LTSA-MD. Results All the regression analyses showed that LTSA-MD was associated with female sex, self-reported white skin color, higher education level, high tobacco consumption, high alcohol intake, two or more comorbidities, exposure to violence at work, high job strain and low social support at work, effort-reward imbalance and high overcommitment to work. LTSA-MD was associated with separate and combined DCS and ERI stress models. Conclusions Individual features and work conditions were associated with LTSA-MD. Combined analysis of stress models showed that psychosocial factors at work were significantly associated with LTSA-MD. Resourceful use of this information may contribute to the

  2. Estimation of plant water content by spectral absorption features centered at 1,450 nm and 1,940 nm regions.

    PubMed

    Wang, Jie; Xu, Ruisong; Yang, Shilun

    2009-10-01

    Vegetation water content could possibly provide widespread utility in agriculture, forestry and hydrology. In this article, three species leaves were measured radiometrically in order to determine a relationship between leaf water status and the spectral feature centered at 1,450 and 1,940 nm where there are strong water absorptions. The first step of our research is to measure leaf spectra with a FieldSpec-FR. After the spectral analysis using the continuum removal technique, the spectral absorption feature parameters: absorption band depth (D (1450), D (1940)), the normalized band depth of absorption in 1,450 and 1,940 nm (BNA(1450), BNA(1940)), the ratio of the two reflectance of continuum line (R (1450i )/R (1940i )), the ratio of the two band depth (D (1450)/D (1940)) and the ratio of the two absorption areas (A (1450)/A (1940)) in the two wavebands were extracted from each leaf spectrum. The fuel moisture content (FMC), specific leaf weight (SLW), equivalent water thickness (EWT) were measured for each leaf sample. A correlation analysis was conducted between the spectral absorption feature parameters and corresponding FMC, SLW and EWT. In addition, some existing indices for assessing water status such as WI (water index), WI/NDVI (water index/normalized difference vegetation index), MSI (moisture stress index), NDWI (normalized difference water index)were calculated and the correlation between them and water status were analyzed too. The results by comparing the correlations indicated that the spectral absorption feature indices we proposed were better. The indexes BNA(1940), D (1450)/D (1940), and A (1450)/A (1940) were well correlated with FMC, and the correlation between the indexes D (1450,) D (1940), R (1450i )/R (1940i ) and EWT were strong. The index A (1450)/A (1940) was tested to be a good indictor for evaluating plant water content, because there was strongest positive correlation between it and FMC than other indices. PMID:18853268

  3. Mood disorder with mixed, psychotic features due to vitamin b12 deficiency in an adolescent: case report.

    PubMed

    Tufan, Ali Evren; Bilici, Rabia; Usta, Genco; Erdoğan, Ayten

    2012-01-01

    Vitamin B12 is one of the essential vitamins affecting various systems of the body. Reports of psychiatric disorders due to its deficiency mostly focus on middle aged and elderly patients. Here we report a case of vitamin B 12 deficiency in a 16-year old, male adolescent who presented with mixed mood disorder symptoms with psychotic features. Chief complaints were "irritability, regressive behavior, apathy, crying and truancy" which lasted for a year. Premorbid personality was unremarkable with no substance use/exposure or infections. No stressors were present. The patient was not vegetarian. Past medical history and family history was normal. Neurological examination revealed glossitis, ataxia, rigidity in both shoulders, cog-wheel rigidity in the left elbow, bilateral problems of coordination in cerebellar examination, reduced swinging of the arms and masked face. Romberg's sign was present. Laboratory evaluations were normal. Endoscopy and biopsy revealed atrophy of the gastric mucosa with Helicobacter Pylori colonization. Schilling test was suggestive of malabsorbtion. He was diagnosed with Mood disorder with Mixed, Psychotic Features due to Vitamin B12 Deficiency and risperidone 0.5 mg/day and intramuscular vitamin B12 500 mcg/day were started along with referral for treatment of Helicobacter pylori. A visit on the second week revealed no psychotic features. Romberg's sign was negative and cerebellar tests were normal. Extrapyramidal symptoms were reduced while Vitamin B12 levels were elevated. Risperidone was stopped and parenteral Vitamin B12 treatment was continued with monthly injections for 3 months. Follow-up endoscopy and biopsy at the first month demonstrated eradication of H. pylori. He was followed monthly for another 6 months and psychiatric symptoms did not recur at the time of last evaluation. Despite limitations, this case may underline the observation that mood disorders with psychotic features especially with accompanying extrapyramidal

  4. Mood disorder with mixed, psychotic features due to vitamin b12 deficiency in an adolescent: case report

    PubMed Central

    2012-01-01

    Vitamin B12 is one of the essential vitamins affecting various systems of the body. Reports of psychiatric disorders due to its deficiency mostly focus on middle aged and elderly patients. Here we report a case of vitamin B 12 deficiency in a 16-year old, male adolescent who presented with mixed mood disorder symptoms with psychotic features. Chief complaints were “irritability, regressive behavior, apathy, crying and truancy” which lasted for a year. Premorbid personality was unremarkable with no substance use/exposure or infections. No stressors were present. The patient was not vegetarian. Past medical history and family history was normal. Neurological examination revealed glossitis, ataxia, rigidity in both shoulders, cog-wheel rigidity in the left elbow, bilateral problems of coordination in cerebellar examination, reduced swinging of the arms and masked face. Romberg’s sign was present. Laboratory evaluations were normal. Endoscopy and biopsy revealed atrophy of the gastric mucosa with Helicobacter Pylori colonization. Schilling test was suggestive of malabsorbtion. He was diagnosed with Mood disorder with Mixed, Psychotic Features due to Vitamin B12 Deficiency and risperidone 0.5 mg/day and intramuscular vitamin B12 500 mcg/day were started along with referral for treatment of Helicobacter pylori. A visit on the second week revealed no psychotic features. Romberg’s sign was negative and cerebellar tests were normal. Extrapyramidal symptoms were reduced while Vitamin B12 levels were elevated. Risperidone was stopped and parenteral Vitamin B12 treatment was continued with monthly injections for 3 months. Follow-up endoscopy and biopsy at the first month demonstrated eradication of H. pylori. He was followed monthly for another 6 months and psychiatric symptoms did not recur at the time of last evaluation. Despite limitations, this case may underline the observation that mood disorders with psychotic features especially with accompanying

  5. Assessment of the deformation of the Bateman bipolar hip prosthesis inner bearing due to moisture absorption and creep.

    PubMed

    Lockie, K; Binns, M; Fisher, J; Jobbins, B

    1992-01-01

    The mechanism of inner bearing stiffness of bipolar hip prostheses has been investigated. The Ultra-high Molecular Weight Polyethylene (UHMWPE) component of the Bateman bipolar hip prosthesis has been subjected to a series of static and dynamic tests to assess water absorption and creep. Although deformation of the UHMWPE occurred, this did not produce an increased resistance to movement in the inner bearing. PMID:1572706

  6. Nonlinear Heart Rate Variability features for real-life stress detection. Case study: students under stress due to university examination

    PubMed Central

    2011-01-01

    Background This study investigates the variations of Heart Rate Variability (HRV) due to a real-life stressor and proposes a classifier based on nonlinear features of HRV for automatic stress detection. Methods 42 students volunteered to participate to the study about HRV and stress. For each student, two recordings were performed: one during an on-going university examination, assumed as a real-life stressor, and one after holidays. Nonlinear analysis of HRV was performed by using Poincaré Plot, Approximate Entropy, Correlation dimension, Detrended Fluctuation Analysis, Recurrence Plot. For statistical comparison, we adopted the Wilcoxon Signed Rank test and for development of a classifier we adopted the Linear Discriminant Analysis (LDA). Results Almost all HRV features measuring heart rate complexity were significantly decreased in the stress session. LDA generated a simple classifier based on the two Poincaré Plot parameters and Approximate Entropy, which enables stress detection with a total classification accuracy, a sensitivity and a specificity rate of 90%, 86%, and 95% respectively. Conclusions The results of the current study suggest that nonlinear HRV analysis using short term ECG recording could be effective in automatically detecting real-life stress condition, such as a university examination. PMID:22059697

  7. Correlated visible-light absorption and intrinsic magnetism of SrTiO3 due to oxygen deficiency: bulk or surface effect?

    PubMed

    Choi, Heechae; Song, Jin Dong; Lee, Kwang-Ryeol; Kim, Seungchul

    2015-04-20

    The visible-light absorption and luminescence of wide band gap (3.25 eV) strontium titanate (SrTiO3) are well-known, in many cases, to originate from the existence of natural oxygen deficiency in the material. In this study based on density functional theory (DFT) calculations, we provide, to the best of our knowledge, the first report indicating that oxygen vacancies in the bulk and on the surfaces of SrTiO3 (STO) play different roles in the optical and magnetic properties. We found that the doubly charged state of oxygen vacancy (VO(2+)) is dominant in bulk SrTiO3 and does not contribute to the sub-band gap photoexcitation or intrinsic magnetism of STO. Neutral oxygen vacancies (VO(0)) on (001) surfaces terminated with both TiO2 and SrO layers induce magnetic moments, which are dependent on the charged state of VO. The calculated absorption spectra for the (001) surfaces exhibit mid-infrared absorption (<0.5 eV) and sub-band gap absorption (2.5-3.1 eV) due to oxygen vacancies. In particular, VO(0) on the TiO2-terminated surface has a relatively low formation energy and magnetic moments, which can explain the recently observed spin-dependent photon absorptions of STO in a magnetic circular dichroism measurement [Rice, W. D.; et al. Nat. Mater.13, 481, 2014]. PMID:25815532

  8. Absolute calibration and atmospheric versus mineralogic origin of absorption features in 2.0 to 2.5 micron Mars spectra obtained during 1993

    NASA Technical Reports Server (NTRS)

    Bell, James F., III; Pollack, James B.; Geballe, Thomas R.; Cruikshank, Dale P.; Freedman, Richard

    1994-01-01

    We obtained new high resolution reflectance spectra of Mars during the 1993 opposition from Mauna Kea Observatory using the UKIRT CGS4 spectrometer. Fifty spectra of 1600-2000 km surface regions and a number of standard star spectra were obtained in the 2.04 to 2.44 micron wavelength region on 4 February 1993 UT. Near-simultaneous observations of bright standard stars were used to perform terrestrial atmospheric corrections and an absolute flux calibration. Using the known magnitude of the stars and assuming blackbody continuum behavior, the flux from Mars could be derived. A radiative transfer model and the HITRAN spectral line data base were used to compute atmospheric transmission spectra for Mars and the Earth in order to simulate the contributions of these atmospheres to our observed data. Also, we examined the ATMOS solar spectrum in the near-IR to try to identify absorption features in the spectrum of the Sun that could be misinterpreted as Mars features. Eleven absorption features were detected in our Mars spectra. Our data provide no conclusive identification of the mineralogy responsible for the absorption features we detected. However, examination of terrestrial spectral libraries and previous high spectral resolution mineral studies indicates that the most likely origin of these features is either CO3(sup 2-), HCO3(-), or HSO4(-) anions in framework silicates or possibly (Fe, Mg)-OH bonds in sheet silicates.

  9. Physical properties of coronal mass ejection plasma associated with erupting prominences as seen emission or absorption features in EUV and X-rays

    NASA Astrophysics Data System (ADS)

    Lee, Jin-Yi; Raymond, John C.; Reeves, Kathy; Moon, Yong-Jae; Kim, Kap-Sung

    2016-05-01

    We investigate the physical properties (temperature, density, mass, and energy) of coronal mass ejection plasmas observed by the Atmospheric Imaging Assembly on Solar Dynamics Observatory and X-ray Telescope on Hinode. The prominences are seen as absorption features in EUV at the beginning of their eruptions. Later the prominences change to emission features during eruptions, which indicates the heating of the erupting plasma. We find the temperatures and densities of the erupting prominences using absorption properties of hydrogen and helium in different passbands. We estimate the temperatures and densities of the erupting plasma in emission features using differential emission measure method, which uses both EUV and X-ray observations applying various spectra using photospheric and coronal abundances. We verify and discuss the methods for the estimation of temperatures and densities for erupting plasmas. Lastly, we discuss the heating of the coronal mass ejection plasmas.

  10. Spectroscopy of Mars form 2.04 to 2.44 micron during the 1993 opposition: Absolute calibration and atmospheric vs mineralogic origin of narrow absorption features

    NASA Technical Reports Server (NTRS)

    Bell, James F., III; Pollack, James B.; Geballe, Thomas R.; Cruikshank, Dale P.; Freedman, Richard

    1994-01-01

    We present moderate-resolution (lambda/delta lambda = 300 to 370) reflectance spectral of Mars from 2.04 to 2.44 microns that were obtained at United Kingdom Infrared Telescope (UKIRT) during the 1993 opposition. Seven narrow absorption features were detected and found to have a Mars origin. By comparison with solar and Mars atmospheric spectra, five of these features were attributed all or in part to Mars atmospheric CO2 or CO (2.052 +/- 0.003, 2.114 +/- 0.002, 2.150 +/- 0.003, 2.331 +/- 0.001, and 2.357 +/- 0.002 microns). Two of the bands (2.331 +/- 0.001 and 2.357 +/- 0.002 micron) appear to have widths and depths that are consistent with additional, nonatmospheric absorptions, although a solar contribution cannot be entirely ruled out. Two other weak bands centered at 2.278 +/- 0.002 and 2.296 +/- 0.002 microns may be at least partially mineralogic in origin. The data provide no conclusive identification of the mineralogy responsible for these absorption features. However, examination of terrestrial spectral libraries and previous mineralogy responsible for these absorption features. However, examination of terrestrial spectral libraires and previous moderate spectral resolution mineral studies indicates that the most likely origin of these features is either (bi)carbonate or (bi)sulfate anions in framework silicates of (Fe, Mg)-OH bonds in sheet silicates. If the bands are caused by phyllosilicate minerals, then an explanation must be found for the extremely narrow widths of the cation-OH features in the Mars spectra as compared to terrestrial minerals.

  11. The enhancement of cosmic radio noise absorption due to hiss-driven energetic electron precipitation during substorms

    NASA Astrophysics Data System (ADS)

    Li, Haimeng; Yuan, Zhigang; Yu, Xiongdong; Huang, Shiyong; Wang, Dedong; Wang, Zhenzhen; Qiao, Zheng; Wygant, John R.

    2015-07-01

    The Van Allen probes, low-altitude NOAA satellite, MetOp satellite, and riometer are used to analyze variations of precipitating energetic electron fluxes and cosmic radio noise absorption (CNA) driven by plasmaspheric hiss with respect to geomagnetic activities. The hiss-driven energetic electron precipitations (at L ~ 4.7-5.3, magnetic local time (MLT) ~ 8-9) are observed during geomagnetic quiet condition and substorms, respectively. We find that the CNA detected by riometers increased very little in the hiss-driven event during quiet condition on 6 September 2012. The hiss-driven enhancement of riometer was still little during the first substorm on 30 September 2012. However, the absorption detected by the riometer largely increased, while the energies of the injected electrons became higher during the second substorm on 30 September 2012. The enhancement of CNA (ΔCNA) observed by the riometer and calculated with precipitating energetic electrons is in agreement during the second substorm, implying that the precipitating energetic electrons increase CNA to an obviously detectable level of the riometer during the second substorm on 30 September 2012. The conclusion is consistent with Rodger et al. (2012), which suggest that the higher level of ΔCNA prefers to occur in the substorms, because substorms may produce more intense energetic electron precipitation associated with electron injection. Furthermore, the combination of the observations and theory calculations also suggests that higher-energy electron (>55 keV) precipitation contributes more to the ΔCNA than the lower energy electron precipitation. In this paper, the higher-energy electron precipitation is related to lower frequency hiss.

  12. The D2O absorption spectra in SiO2 airgel pores: technical features of treatment

    NASA Astrophysics Data System (ADS)

    Lugovskoi, A.; Duchko, A.

    2015-11-01

    The dynamic of the D2O in silica airgel absorption spectra in 4000…6000 cm-1 were recorded using Fourier Transform spectrometer FS-125M at room temperature and pressure of 23.4 mbar with spectral resolution of 0.03 cm-1. It is shown that the D2O dimers to make a significant contribution into absorption when nanopores filled with gas molecules is small. Is present a detailed description of techniques for processing the primary experimental data.

  13. Relating Aerosol Absorption due to Soot, Organic Carbon, and Dust to Emission Sources Determined from In-situ Chemical Measurements

    SciTech Connect

    Cazorla, Alberto; Bahadur, R.; Suski, Kaitlyn; Cahill, John F.; Chand, Duli; Schmid, Beat; Ramanathan, V.; Prather, Kimberly

    2013-09-17

    Estimating the aerosol contribution to the global or regional radiative forcing can take advantage of the relationship between the spectral aerosol optical properties and the size and chemical composition of aerosol. Long term global optical measurements from observational networks or satellites can be used in such studies, and using in-situ chemical mixing state measurements can help us to constrain the limitations of such an estimation. In this study, the Absorption Ångström Exponent (AAE) and the Scattering Ångström Exponent (SAE) are used to develop a new methodology for deducing chemical speciation based on wavelength dependence of the optical properties. In addition, in-situ optical properties and single particle chemical composition measured during three aircraft field campaigns are combined in order to validate the methodology for the estimation of aerosol composition using spectral optical properties. Results indicate a dominance of mixed types in the classification leading to an underestimation of the primary sources, however secondary sources are better classified. The distinction between carbonaceous aerosols from fossil fuel and biomass burning origins is not clear. On the other hand, the knowledge of the aerosol sources in California from chemical studies help to identify other misclassification such as the dust contribution.

  14. Papular dermatitis due to Leishmania infantum infection in seventeen dogs: diagnostic features, extent of the infection and treatment outcome

    PubMed Central

    2014-01-01

    Background This study describes immunological responses, diagnostic features, follow up and treatment outcomes from seventeen dogs with papular dermatitis due to Leishmania infection diagnosed by cytology or real time-PCR. Methods Specific Leishmania humoral and cellular immune responses were evaluated by means of an immunofluorescence antibody test in all cases and a delayed-type hypersensitivity (DTH) reaction to leishmanin in eight cases. The extent of infection was studied in several tissues including blood, lymph node, conjunctival and oral swabs, by means of PCR, at the time of diagnosis and during follow-up. Culture was performed on nine dogs from cutaneous lesions and lymph node aspirates and molecular typing was carried out on isolates based on ITS-1, ITS-2 and Haspb gene sequencing analysis. Results Cytological and molecular results from fine needle aspirates of papules were diagnostic in 8 out of 13 (61.5%) cases and in 14 out of 15 dogs (93.3%), respectively. In all dogs, specific anti-Leishmania antibody levels were low or absent. Blood and lymph node PCRs and lymph node culture were negative in all dogs. Three out of the nine dogs (33%) were positive by culture from cutaneous lesions. The three isolates were identified as ITS type A, however, polymorphism was observed in the Haspb gene (PCR products of 626 bp, 962 bp and 371 bp). DTH response was positive in all tested dogs at the time of diagnosis. The majority of dogs were successfully treated with only N-methylglucamine antimoniate, after which cutaneous lesions disappeared or were reduced to depigmented, flattened scars. All dogs remained seronegative and the majority of dogs were negative by PCR in several tissues during follow-up. Conclusions This study points out that papular dermatitis due to L. infantum is probably an underestimated benign cutaneous problem, associated with a parasite specific cell mediated immunity and a poor humoral immune response. Papular dermatitis is seen in young dogs

  15. Physiological roles of dietary glutamate signaling via gut-brain axis due to efficient digestion and absorption.

    PubMed

    Torii, Kunio; Uneyama, Hisayuki; Nakamura, Eiji

    2013-04-01

    Dietary glutamate (Glu) stimulates to evoke the umami taste, one of the five basic tastes, enhancing food palatability. But it is also the main gut energy source for the absorption and metabolism for each nutrient, thus, only a trace amount of Glu reaches the general circulation. Recently, we demonstrated a unique gut sensing system for free Glu (glutamate signaling). Glu is the only nutrient among amino acids, sugars and electrolytes that activates rat gastric vagal afferents from the luminal side specifically via metabotropic Glu receptors type 1 on mucosal cells releasing mucin and nitrite mono-oxide (NO), then NO stimulates serotonin (5HT) release at the enterochromaffin cell. Finally released 5HT stimulates 5HT3 receptor at the nerve end of the vagal afferent fiber. Functional magnetic resonance imaging (f-MRI, 4.7 T) analysis revealed that luminal sensing with 1 % (w/v) monosodium L-glutamate (MSG) in rat stomach activates both the medial preoptic area (body temperature controller) and the dorsomedial hypothalamus (basic metabolic regulator), resulting in diet-induced thermogenesis during mealing without changes of appetite for food. Interestingly, rats were forced to eat a high fat and high sugar diet with free access to 1 % (w/w) MSG and water in a choice paradigm and showed the strong preference for the MSG solution and subsequently, they displayed lower fat deposition, weight gain and blood leptin. On the other hand, these brain functional changes by the f-MRI signal after 60 mM MSG intubation into the stomach was abolished in the case of total vagotomized rats, suggesting that luminal glutamate signaling contributes to control digestion and thermogenesis without obesity. PMID:23463402

  16. Anomalous atmospheric spectral features between 300 and 310 nm interpreted in light or new ozone absorption coefficient measurements

    NASA Technical Reports Server (NTRS)

    Mcpeters, R. D.; Bass, A. M.

    1982-01-01

    Real structure is revealed, by an analysis of continuous scan data from the solar backscattered UV instrument on Nimbus 7, in the backscattered atmospheric albedo region between 300 and 310 nm where spectral anomalies have been reported in ground-based observation. The spectral anomalies are explainable as structure at the 1-5% level in the ozone absorption coefficient, as measured by Bass and Paur (1981). The new absorption coefficient measurements are judged to approach the 1%-level of accuracy in atmospheric radiation calculation, which should resolve discrepancies between different Dobson wavelength pairs and between different instruments and permit the more accurate analysis of such second-order effects as NO emission, SO2 absorption in polluted atmospheres, and Raman scattering effects.

  17. Spectroscopy of Mars from 2.04 to 2.44 micrometers during the 1993 opposition: absolute calibration and atmospheric vs mineralogic origin of narrow absorption features.

    PubMed

    Bell JF 3rd; Pollack, J B; Geballe, T R; Cruikshank, D P; Freedman, R

    1994-09-01

    We present moderate-resolution (lambda/delta lambda = 300 to 370) reflectance spectra of Mars from 2.04 to 2.44 micrometers that were obtained at UKIRT during the 1993 opposition. Seven narrow absorption features were detected and found to have a Mars origin. By comparison with solar and Mars atmospheric spectra, five of these features were attributed all or in part to Mars atmospheric CO2 or CO(2.052 +/- 0.003, 2.114 +/- 0.002, 2.150 +/- 0.003, 2.331 +/- 0.001, and 2.357 +/- 0.002 micrometers). Two of the bands (2.331 +/- 0.001 and 2.357 +/- 0.002 micrometers) appear to have widths and depths that are consistent with additional, nonatmospheric absorptions, although a solar contribution cannot be entirely ruled out. Two other weak bands centered at 2.278 +/- 0.002 and 2.296 +/- 0.002 micrometers may be at least partially mineralogic in origin. The data provide no conclusive identification of the mineralogy responsible for these absorption features. However, examination of terrestrial spectral libraries and previous moderate spectral resolution mineral studies indicates that the most likely origin of these features is either (bi)carbonate or (bi)sulfate anions in framework silicates or (Fe, Mg)-OH bonds in sheet silicates. If the bands are caused by phyllosilicate minerals, then an explanation must be found for the extremely narrow widths of the cation-OH features in the Mars spectra as compared to terrestrial minerals. PMID:11539175

  18. Spectroscopy of Mars from 2.04 to 2.44 micrometers during the 1993 opposition: absolute calibration and atmospheric vs mineralogic origin of narrow absorption features

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.; Geballe, T. R.; Cruikshank, D. P.; Freedman, R.

    1994-01-01

    We present moderate-resolution (lambda/delta lambda = 300 to 370) reflectance spectra of Mars from 2.04 to 2.44 micrometers that were obtained at UKIRT during the 1993 opposition. Seven narrow absorption features were detected and found to have a Mars origin. By comparison with solar and Mars atmospheric spectra, five of these features were attributed all or in part to Mars atmospheric CO2 or CO(2.052 +/- 0.003, 2.114 +/- 0.002, 2.150 +/- 0.003, 2.331 +/- 0.001, and 2.357 +/- 0.002 micrometers). Two of the bands (2.331 +/- 0.001 and 2.357 +/- 0.002 micrometers) appear to have widths and depths that are consistent with additional, nonatmospheric absorptions, although a solar contribution cannot be entirely ruled out. Two other weak bands centered at 2.278 +/- 0.002 and 2.296 +/- 0.002 micrometers may be at least partially mineralogic in origin. The data provide no conclusive identification of the mineralogy responsible for these absorption features. However, examination of terrestrial spectral libraries and previous moderate spectral resolution mineral studies indicates that the most likely origin of these features is either (bi)carbonate or (bi)sulfate anions in framework silicates or (Fe, Mg)-OH bonds in sheet silicates. If the bands are caused by phyllosilicate minerals, then an explanation must be found for the extremely narrow widths of the cation-OH features in the Mars spectra as compared to terrestrial minerals.

  19. Moderate-resolution spectroscopy of the lensed quasar 2237 + 0305 - A search for CA II absorption due to the interstellar medium in the foreground lensing galaxy

    NASA Astrophysics Data System (ADS)

    Hintzen, Paul; Maran, Stephen P.; Michalitsianos, Andrew G.; Foltz, Craig B.; Chaffee, Frederic H., Jr.; Kafatos, Minas

    1990-01-01

    The gravitational lens system 2237+0305 consists of a low-redshift barred spiral galaxy (z = 0.0394) centered on a more distant quasar (z = 1.695). Because the lensing galaxy is nearly face on, spectroscopy of the background quasar affords a unique opportunity to study the interstellar medium in the galaxy's center and . We report moderate-resolution spectroscopy of QSO2237+0305 yielding a 3σ upper limit of 72 mÅ for the rest equivalent width of Ca II K absorption due to gas in the intervening galaxy. Since gas in the Milky Way "thick disk" typically produces 220 mÅ Ca II lines along lines of sight at high galactic latitude, while our line of sight to QSO 2237+0305 is effectively the weighted mean of four lines of sight, each of which transects an entire halo diameter in the lensing galaxy rather than just a radius, our Ca II upper limit argues against the presence of such a thick disk near the center of the lensing galaxy. Also, published studies indicate that at 8200 Å, QSO 2237+0305 suffers roughly 0.5 mag of extinction due to the leasing galaxy. Assuming a normal gas-to-dust ratio and allowing for various sources of uncertainty, this absorption estimate combined with our Ca II K upper limit implies that calcium is depleted with respect to hydrogen by at least 2.7-3.7 dex, compared to solar abundances. This depletion is similar to the more extreme cases seen in our own galaxy, and higher-dispersion observations may further decrease the upper limit on Ca II absorption.

  20. The first UV absorption band of l-tryptophan is not due to two simultaneous orthogonal electronic transitions differing in the dipole moment.

    PubMed

    Catalán, Javier

    2016-06-01

    Based on UV/Vis spectroscopic evidence obtained in this work, the first band in the absorption spectrum of l-tryptophan is largely due to a single electronic transition from the ground state to the (1)Lb excited state. However, emission spectra of this compound recorded at a variable temperature in ethanol, n-butanol and diethyl ether are structureless and considerably red-shifted at room temperature; also, lowering the temperature causes the emission to become structured and to undergo such a strong blue shift that it appears to be due to the (1)Lb state of the compound. Based on these findings, the formation (from the excited (1)Lb state) of the excited state responsible for the structureless, markedly red-shifted emission in l-tryptophan is strongly dependent not only on the viscosity of the medium, but also on its dipolarity. PMID:27197597

  1. FIRST ULTRAVIOLET REFLECTANCE SPECTRA OF PLUTO AND CHARON BY THE HUBBLE SPACE TELESCOPE COSMIC ORIGINS SPECTROGRAPH: DETECTION OF ABSORPTION FEATURES AND EVIDENCE FOR TEMPORAL CHANGE

    SciTech Connect

    Stern, S. A.; Spencer, J. R.; Shinn, A.; Cunningham, N. J.; Hain, M. J.

    2012-01-15

    We have observed the mid-UV spectra of both Pluto and its large satellite, Charon, at two rotational epochs using the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) in 2010. These are the first HST/COS measurements of Pluto and Charon. Here we describe the observations and our reduction of them, and present the albedo spectra, average mid-UV albedos, and albedo slopes we derive from these data. These data reveal evidence for a strong absorption feature in the mid-UV spectrum of Pluto; evidence for temporal change in Pluto's spectrum since the 1990s is reported, and indirect evidence for a near-UV spectral absorption on Charon is also reported.

  2. High sensitivity liquid phase measurements using broadband cavity enhanced absorption spectroscopy (BBCEAS) featuring a low cost webcam based prism spectrometer.

    PubMed

    Qu, Zhechao; Engstrom, Julia; Wong, Donald; Islam, Meez; Kaminski, Clemens F

    2013-11-01

    Cavity enhanced techniques enable high sensitivity absorption measurements in the liquid phase but are typically more complex, and much more expensive, to perform than conventional absorption methods. The latter attributes have so far prevented a wide spread use of these methods in the analytical sciences. In this study we demonstrate a novel BBCEAS instrument that is sensitive, yet simple and economical to set up and operate. We use a prism spectrometer with a low cost webcam as the detector in conjunction with an optical cavity consisting of two R = 0.99 dielectric mirrors and a white light LED source for illumination. High sensitivity liquid phase measurements were made on samples contained in 1 cm quartz cuvettes placed at normal incidence to the light beam in the optical cavity. The cavity enhancement factor (CEF) with water as the solvent was determined directly by phase shift cavity ring down spectroscopy (PS-CRDS) and also by calibration with Rhodamine 6G solutions. Both methods yielded closely matching CEF values of ~60. The minimum detectable change in absorption (αmin) was determined to be 6.5 × 10(-5) cm(-1) at 527 nm and was limited only by the 8 bit resolution of the particular webcam detector used, thus offering scope for further improvement. The instrument was used to make representative measurements on dye solutions and in the determination of nitrite concentrations in a variation of the widely used Griess Assay. Limits of detection (LOD) were ~850 pM for Rhodamine 6G and 3.7 nM for nitrite, respectively. The sensitivity of the instrument compares favourably with previous cavity based liquid phase studies whilst being achieved at a small fraction of the cost hitherto reported, thus opening the door to widespread use in the community. Further means of improving sensitivity are discussed in the paper. PMID:24049768

  3. Atmospheric Profiling Combining the Features of GPS ro & Mls: Satellite to Satellite Occultations Near Water & Ozone Absorption Lines

    NASA Astrophysics Data System (ADS)

    Kursinski, E. R.; Ward, D.; Otarola, A. C.; McGhee, J.; Reed, H.; Erickson, D.

    2015-12-01

    Assessing climate models & their predictions requires observations that determine the state of the real climate system precisely and unambiguously, independently from models. For this purpose, we have been developing a new orbiting remote sensing system called the Active Temperature, Ozone & Moisture Microwave Spectrometer (ATOMMS) which is a cross between GPS RO and the Microwave Limb Sounder. ATOMMS actively probes water vapor, ozone & other absorption lines at cm & mm wavelengths in a satellite to satellite occultation geometry to simultaneously profile temperature, pressure, water vapor and ozone as well as other important constituents. Individual profiles of water vapor, temperature & pressure heights will extend from near the surface into the mesosphere with ~1%, 0.4K and 10 m precision respectively and still better accuracy, with 100 m vertical resolution. Ozone profiles will extend upward from the upper troposphere. Line of sight wind profiles will extend upwards from the mid-stratosphere. ATOMMS is a doubly differential absorption system which eliminates drift and both sees clouds and sees thru them, to deliver performance in clouds within a factor of 2 of the performance in clear skies. This all-weather sampling combined with insensitivity to surface emissivity avoids sampling biases that limit most existing satellite records. ATOMMS will profile slant liquid water in clouds & rain and as well as turbulence via scintillations ("twinkling of a star"). Using prototype ATOMMS instrumentation that we developed with funding from NSF, several ATOMMS ground field campaigns precisely measured water vapor, cloud amount, rainfall, turbulence and absorption line spectroscopy. ATOMMS's dynamic range was demonstrated as water vapor was derived to 1% precision in optical depths up to 17. We are developing high altitude aircraft to aircraft instrumentation to further demonstrate ATOMMS performance, refine spectroscopy & support future field campaigns. Our vision is a

  4. L-asparagine crystals with wide gap semiconductor features: Optical absorption measurements and density functional theory computations

    NASA Astrophysics Data System (ADS)

    Zanatta, G.; Gottfried, C.; Silva, A. M.; Caetano, E. W. S.; Sales, F. A. M.; Freire, V. N.

    2014-03-01

    Results of optical absorption measurements are presented together with calculated structural, electronic, and optical properties for the anhydrous monoclinic L-asparagine crystal. Density functional theory (DFT) within the generalized gradient approximation (GGA) including dispersion effects (TS, Grimme) was employed to perform the calculations. The optical absorption measurements revealed that the anhydrous monoclinic L-asparagine crystal is a wide band gap material with 4.95 eV main gap energy. DFT-GGA+TS simulations, on the other hand, produced structural parameters in very good agreement with X-ray data. The lattice parameter differences Δa, Δb, Δc between theory and experiment were as small as 0.020, 0.051, and 0.022 Å, respectively. The calculated band gap energy is smaller than the experimental data by about 15%, with a 4.23 eV indirect band gap corresponding to Z → Γ and Z → β transitions. Three other indirect band gaps of 4.30 eV, 4.32 eV, and 4.36 eV are assigned to α3 → Γ, α1 → Γ, and α2 → Γ transitions, respectively. Δ-sol computations, on the other hand, predict a main band gap of 5.00 eV, just 50 meV above the experimental value. Electronic wavefunctions mainly originating from O 2p-carboxyl, C 2p-side chain, and C 2p-carboxyl orbitals contribute most significantly to the highest valence and lowest conduction energy bands, respectively. By varying the lattice parameters from their converged equilibrium values, we show that the unit cell is less stiff along the b direction than for the a and c directions. Effective mass calculations suggest that hole transport behavior is more anisotropic than electron transport, but the mass values allow for some charge mobility except along a direction perpendicular to the molecular layers of L-asparagine which form the crystal, so anhydrous monoclinic L-asparagine crystals could behave as wide gap semiconductors. Finally, the calculations point to a high degree of optical anisotropy for the

  5. L-asparagine crystals with wide gap semiconductor features: Optical absorption measurements and density functional theory computations

    SciTech Connect

    Zanatta, G.; Gottfried, C.; Silva, A. M.; Caetano, E. W. S.; Sales, F. A. M.; Freire, V. N.

    2014-03-28

    Results of optical absorption measurements are presented together with calculated structural, electronic, and optical properties for the anhydrous monoclinic L-asparagine crystal. Density functional theory (DFT) within the generalized gradient approximation (GGA) including dispersion effects (TS, Grimme) was employed to perform the calculations. The optical absorption measurements revealed that the anhydrous monoclinic L-asparagine crystal is a wide band gap material with 4.95 eV main gap energy. DFT-GGA+TS simulations, on the other hand, produced structural parameters in very good agreement with X-ray data. The lattice parameter differences Δa, Δb, Δc between theory and experiment were as small as 0.020, 0.051, and 0.022 Å, respectively. The calculated band gap energy is smaller than the experimental data by about 15%, with a 4.23 eV indirect band gap corresponding to Z → Γ and Z → β transitions. Three other indirect band gaps of 4.30 eV, 4.32 eV, and 4.36 eV are assigned to α3 → Γ, α1 → Γ, and α2 → Γ transitions, respectively. Δ-sol computations, on the other hand, predict a main band gap of 5.00 eV, just 50 meV above the experimental value. Electronic wavefunctions mainly originating from O 2p–carboxyl, C 2p–side chain, and C 2p–carboxyl orbitals contribute most significantly to the highest valence and lowest conduction energy bands, respectively. By varying the lattice parameters from their converged equilibrium values, we show that the unit cell is less stiff along the b direction than for the a and c directions. Effective mass calculations suggest that hole transport behavior is more anisotropic than electron transport, but the mass values allow for some charge mobility except along a direction perpendicular to the molecular layers of L-asparagine which form the crystal, so anhydrous monoclinic L-asparagine crystals could behave as wide gap semiconductors. Finally, the calculations point to a high degree of optical

  6. A HIRES Detection of NA I D Absorption in the Spectrum of the QSO PKS 2020-370 Due to the Galaxy Klemola 31A

    NASA Astrophysics Data System (ADS)

    Junkkarinen, V. T.; Barlow, T. A.

    1994-12-01

    By using the Keck telescope and HIRES spectrograph we have detected Na I D absorption lines in the spectrum of the QSO PKS 2020-370 (V = 17.5, z = 1.048) due to the galaxy Klemola 31A (z = 0.0288). The PKS 2020-370 line of sight is near an apparent spiral arm only 20" from the nucleus of Klemola 31A which corresponds to 17 kpc (H_o = 50 km s(-1) Mpc(-1) ). The spectrum of PKS 2020-370 has strong Ca II absorption lines (W_λ ~ 350 m Angstroms \\ for the K line) at the galaxy redshift (Boksenberg et al, 1980, ApJ, 242, L145), but previous attempts to detect Na I have resulted in upper limits (Boisse et al. 1988, A&A, 191, 193, Womble, 1992, thesis UCSD). We observed PKS 2020-370 with HIRES in May 1994 at a resolution of 8 km s(-1) FWHM for a total of 90 minutes. The Na I D doublet is detected with a total W_λ for the Na I 5891.6 Angstroms \\ (vac) absorption line of about 160 m Angstroms . The absorption appears as two main velocity components separated by 23 km s(-1) . The optically thin estimate for N(Na I) = 1.0 times 10(12) cm(-2) gives an estimated N(Ca II)/N(Na I) = 5. This value suggests that the gas in Klemola 31A along the QSO line of sight is ``halo like''. Along ``disk like'' lines of sight where Ca is thought to be depleted onto grains in our Galaxy, the N(Ca II)/N(Na I) ratio is usually small (<= 1). Other QSO--galaxy pairs often show disk like N(Ca II)/N(Na I) ratios when the line of sight intersects starlight at 25 mag per sq. arcsec (Womble, 1992 thesis UCSD). The PKS 2020-370 sightline is near the optical extent of Klemola 31A but the N(Ca II)/N(Na I) is consistent with the sightline passing through two clouds in the halo. This research has been supported in part by NASA NAS5--29293 and NAG5--1630.

  7. Multimodal tissue imaging: using coregistered optical tomography data to estimate tissue autofluorescence intensity change due to scattering and absorption by neoplastic epithelial cells.

    PubMed

    Pahlevaninezhad, Hamid; Cecic, Ivana; Lee, Anthony M D; Kyle, Alastair H; Lam, Stephen; MacAulay, Calum; Lane, Pierre M

    2013-10-01

    Autofluorescence (AF) imaging provides valuable information about the structural and chemical states of tissue that can be used for early cancer detection. Optical scattering and absorption of excitation and emission light by the epithelium can significantly affect observed tissue AF intensity. Determining the effect of epithelial attenuation on the AF intensity could lead to a more accurate interpretation of AF intensity. We propose to use optical coherence tomography coregistered with AF imaging to characterize the AF attenuation due to the epithelium. We present imaging results from three vital tissue models, each consisting of a three-dimensional tissue culture grown from one of three epithelial cell lines (HCT116, OVCAR8, and MCF7) and immobilized on a fluorescence substrate. The AF loss profiles in the tissue layer show two different regimes, each approximately linearly decreasing with thickness. For thin cell cultures (<300 μm), the AF signal changes as AF(t)/AF(0)=1-1.3t (t is the thickness in millimeter). For thick cell cultures (>400 μm), the AF loss profiles have different intercepts but similar slopes. The data presented here can be used to estimate AF loss due to a change in the epithelial layer thickness and potentially to reduce AF bronchoscopy false positives due to inflammation and non-neoplastic epithelial thickening. PMID:24108573

  8. THE 3-5 {mu}m SPECTRUM OF NGC 1068 AT HIGH ANGULAR RESOLUTION: DISTRIBUTION OF EMISSION AND ABSORPTION FEATURES ACROSS THE NUCLEAR CONTINUUM SOURCE

    SciTech Connect

    Geballe, T. R.; Mason, R. E.; Rodriguez-Ardila, A.; Axon, D. J.

    2009-08-20

    We report moderate resolution 3-5 {mu}m spectroscopy of the nucleus of NGC 1068 obtained at 0.''3 (20 pc) resolution with the spectrograph slit aligned approximately along the ionization cones of the active galactic nucleus. The deconvolved full width at half-maximum of the nuclear continuum source in this direction is 0.''3. Four coronal lines of widely different excitations were detected; the intensity of each peaks near radio knot C, approximately 0.''3 north of the infrared continuum peak, where the radio jet changes direction. Together with the broadened line profiles observed near that location, this suggests that shock ionization is the dominant excitation mechanism of the coronal lines. The depth of the 3.4 {mu}m hydrocarbon absorption is maximum at and just south of the continuum peak, similar to the 10 {mu}m silicate absorption. That and the similar and rapid variations of the optical depths of both features across the nucleus suggest that substantial portions of both arise in a dusty environment just in front of the continuum source(s). A new and tighter limit is set on the column density of CO. Although clumpy models of the dust screen might explain the shallowness of the silicate feature, the presence of the 3.4 {mu}m feature and the absence of CO are strongly reminiscent of Galactic diffuse cloud environments and a consistent explanation for them and the observed silicate feature is found if all three phenomena occur in such an environment, existing as close as 10 pc to the central engine.

  9. The Relationship between the Optical Depth of the 9.7 μm Silicate Absorption Feature and Infrared Differential Extinction in Dense Clouds

    NASA Astrophysics Data System (ADS)

    Chiar, J. E.; Ennico, K.; Pendleton, Y. J.; Boogert, A. C. A.; Greene, T.; Knez, C.; Lada, C.; Roellig, T.; Tielens, A. G. G. M.; Werner, M.; Whittet, D. C. B.

    2007-09-01

    We have examined the relationship between the optical depth of the 9.7 μm silicate absorption feature (τ9.7) and the near-infrared color excess, E(J-Ks), in the Serpens, Taurus, IC 5146, Chameleon I, Barnard 59, and Barnard 68 dense clouds/cores. Our data set, based largely on Spitzer IRS spectra, spans E(J-Ks)=0.3-10 mag (corresponding to visual extinction between about 2 and 60 mag). All lines of sight show the 9.7 μm silicate feature. Unlike in the diffuse ISM where a tight linear correlation between the 9.7 μm silicate feature optical depth and the extinction (AV) is observed, we find that the silicate feature in dense clouds does not show a monotonic increase with extinction. Thus, in dense clouds, τ9.7 is not a good measure of total dust column density. With few exceptions, the measured τ9.7 values fall well below the diffuse ISM correlation line for E(J-Ks)>2 mag (AV>12 mag). Grain growth via coagulation is a likely cause of this effect.

  10. Simultaneous soft and hard X-ray spectroscopy of AM Herculis with EXOSAT: Discovery of photospheric absorption features

    NASA Technical Reports Server (NTRS)

    Paerels, Frits; Heise, John; Teeseling, Andre Van

    1994-01-01

    We present 0.1-10 keV spectroscopic observations of AM Herculis obtained with the Transmission Grating Spectrometers and Medium Energy experiments on EXOSAT, taken when the object was in its 'reversed X-ray mode.' The observation covers over six binary orbits without interruption, enabling us to analyze the phase and intensity dependence of both the hard and the soft spectrum simultaneously. We resolve the optically thick soft X-ray spectrum, and find definite evidence for time- and phase-dependent photospheric absorption structure arising in the white dwarf atmosphere. We present a simple empirical analysis of the combined soft and hard X-ray spectra, to examine whether the effect of a better determination of the column density of neutral absorbing material, afforded by our data, would solve the problem of the large relative soft X-ray overluminosity previously observed in AM Her. We find that a single absorbing column fits the entire spectrum, and that the column densities implied are indeed substantially lower than previously estimated. However, during half the binary orbit we still determine a strong lower limit to the soft-to-hard luminosity ratio of L(sub soft)/L(sub hard) is greater than or approximately equal to 10, in conflict with the simple radiative shock models for the accretion region. We argue that this indicates the need to reexamine the luminosity problem using explicit models for the emission spectrum based on a full solution of the atmospheric radiative transfer problem.

  11. Absorption features in the quasar HS 1603 + 3820 II. Distance to the absorber obtained from photoionisation modelling

    NASA Astrophysics Data System (ADS)

    Różańska, A.; Nikołajuk, M.; Czerny, B.; Dobrzycki, A.; Hryniewicz, K.; Bechtold, J.; Ebeling, H.

    2014-04-01

    We present the photoionisation modelling of the intrinsic absorber in the bright quasar HS 1603 + 3820. We constructed the broad-band spectral energy distribution using the optical/UV/X-ray observations from different instruments as inputs for the photoionisation calculations. The spectra from the Keck telescope show extremely high CIV to HI ratios, for the first absorber in system A, named A1. This value, together with high column density of CIV ion, place strong constraints on the photoionisation model. We used two photoionisation codes to derive the hydrogen number density at the cloud illuminated surface. By estimating bolometric luminosity of HS 1603 + 3820 using the typical formula for quasars, we calculated the distance to A1. We could find one photoionization solution, by assuming either a constant density cloud (which was modelled using CLOUDY), or a stratified cloud (which was modelled using TITAN), as well as the solar abundances. This model explained both the ionic column density of CIV and the high CIV to HI ratio. The location of A1 is 0.1 pc, and it is situated even closer to the nucleus than the possible location of the Broad Line Region in this object. The upper limit of the distance is sensitive to the adopted covering factor and the carbon abundance. Photoionisation modelling always prefers dense clouds with the number density n0 = 1010 - 1012 cm-3, which explains intrinsic absorption in HS 1603 + 3820. This number density is of the same order as that in the disk atmosphere at the implied distance of A1. Therefore, our results show that the disk wind that escapes from the outermost accretion disk atmosphere can build up dense absorber in quasars.

  12. Structural features and the reaction mechanism of cytochrome oxidase: iron and copper X-ray absorption fine structure.

    PubMed Central

    Powers, L; Chance, B; Ching, Y; Angiolillo, P

    1981-01-01

    X-ray edge absorption of copper and extended fine structure studies of both copper and iron centers have been made of cytochrome oxidase from beef heart, Paracoccus dentrificans, and HB-8 thermophilic bacteria (1-2.5 mM in heme). The desired redox state (fully oxidized, reduced CO, mixed valence formate and CO) in the x-ray beam was controlled by low temperature (-140 degrees C) and was continuously monitored by simultaneous optical spectroscopy and by electron paramagnetic resonance (EPR) monitoring every 30 min of x-ray exposure. The structure of the active site, a cytochrome a3-copper pair in fully oxidized and in mixed valence formate states where they are spin coupled, contains a sulphur bridge with three ligands 2.60 +/- 0.03 A from Fea3 and 2.18 +/- 0.03 A from Cua3. The distance between Fea3 and Cua3 is 3.75 +/- 0.05 A, making the sulphur bond angle 103 degrees reasonable for sp3 sulphur bonding. The Fea3 first shell has four typical heme nitrogens (2.01 +/- 0.03 A) with a proximal nitrogen at 2.14 +/- 0.03 A. The sixth ligand is the bridging sulphur. The Cua3 first shell is identical to oxidized stellacyanin containing two nitrogens and a bridging sulphur. Upon reduction with CO, the active site is identical to reduced stellacyanin for the Cua3 first shell and contains the sulphur that forms the bridge in fully oxidized and mixed valence formate states. The Fea3 first shell is identical to oxyhemoglobin but has CO instead of O2. The other redox centers, Fea and the other "EPR detectable" Cu are not observed in higher shells of Fea3. Fea has six equidistant nitrogens and Cua has one (or two) nitrogens and three (or two) sulphurs with typical distances; these ligands change only slight on reduction. These structures afford the basis for an oxygen reduction mechanism involving oxy- and peroxy intermediates. Images FIGURE 2 PMID:6264990

  13. Modelling the Emission And/or Absorption Features in the High Resolution Spectra of the Southern Binary System: HH Car

    NASA Astrophysics Data System (ADS)

    Koseoglu, Dogan; Bakış, Hicran

    2016-07-01

    High-resolution spectra (R=48000) of the southern close binary system, HH Car, has been analyzed with modern analysis techniques. Precise absolute parameters were derived from the simultaneous solution of the radial velocity, produced in this study and the light curves, published. According to the results of these analyses, the primary component is an O9 type main sequence star while the secondary component is a giant/subgiant star with a spectral type of B0. Hα emissions can be seen explicitly in the spectra of HH Car. These features were modelled using the absolute parameters of the components. Since components of HH Car are massive early-type stars, mass loss through stellar winds can be expected. This study revealed that the components of HH Car have stellar winds and the secondary component loses mass to the primary. Stellar winds and the gas stream between the components were modelled as a hot shell around the system. It is determined that the interaction between the winds and the gas stream leads to formation of a high temperature impact region.

  14. Errarum: Detection of Absorption-Line Features in the X-Ray Spectra of the Galactic Superluminal Source GRO J1655-40

    NASA Astrophysics Data System (ADS)

    Ueda, Y.; Inoue, H.; Tanaka, Y.; Ebisawa, K.; Nagase, F.; Kotani, T.; Gehrels, N.

    1998-06-01

    In the paper ``Detection of Absorption-Line Features in the X-Ray Spectra of the Galactic Superluminal Source GRO J1655-40'' by Y. Ueda, H. Inoue, Y. Tanaka, K. Ebisawa, F. Nagase, T. Kotani, and N. Gehrels (ApJ, 492, 782 [1998]), there is an error in the curve of growth for the Kα absorption line (Fig. 4). The revised version of Figure 4 given here replaces Figure 4 in the paper. Several numbers derived from the figure should be corrected accordingly, but the conclusion of the paper is not affected. In the third paragraph of the discussion section (page 786), the iron column density of the plasma should be 1019-1020 cm-2, which corresponds to a hydrogen column density of 3 × 1023-3 × 1024 cm-2. The final limit on the hydrogen column density of the line-absorbing plasma should be changed to 3 × 1023 cm-2 < NH < 1024 cm-2.

  15. D-xylose absorption

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003606.htm D-xylose absorption To use the sharing features on this page, please enable JavaScript. D-xylose absorption is a laboratory test to determine ...

  16. Numerical analysis of specific absorption rate in the human head due to a 13.56 MHz RFID-based intra-ocular pressure measurement system.

    PubMed

    Hirtl, Rene; Schmid, Gernot

    2013-09-21

    A modern wireless intra-ocular pressure monitoring system, based on 13.56 MHz inductively coupled data transmission, was dosimetrically analyzed with respect to the specific absorption rate (SAR) induced inside the head and the eye due to the electromagnetic field exposure caused by the reader antenna of the transmission system. The analysis was based on numerical finite difference time domain computations using a high resolution anatomical eye model integrated in a modern commercially available anatomical model of a male head. Three different reader antenna configurations, a 7-turn elliptic (30 mm × 50 mm) antenna at 12 mm distance from the eye, a flexible circular antenna (60 mm diameter, 8 turns on 2 mm substrate) directly attached to the skin, and a circular 7-turn antenna (30 mm diameter at 12 mm distance to the eye) were analyzed, respectively. Possible influences of the eye-lid status (closed or opened) and the transponder antenna contained in a contact lens directly attached to the eye were taken into account. The results clearly demonstrated that for typical reader antenna currents required for proper data transmission, the SAR values remain far below the limits for localized exposure of the head, as defined by the International Commission for Non-Ionizing Radiation Protection. Particularly the induced SAR inside the eye was found to be substantially (orders of magnitudes for typical reader antenna currents in the order of 1 A turn) below values which have been reported to be critical with respect to thermally induced adverse health effects in eye tissues. PMID:24002053

  17. Detection of a z=0.0515, 0.0522 absorption system in the QSO S4 0248+430 due to an intervening galaxy

    NASA Technical Reports Server (NTRS)

    Womble, Donna S.; Junkkarinen, Vesa T.; Cohen, Ross D.; Burbidge, E. Margaret

    1990-01-01

    In some of the few cases where the line of sight to a Quasi-Stellar Object (QSO) passes near a galaxy, the galaxy redshift is almost identical to an absorption redshift in the spectrum of the QSO. Although these relatively low redshift QSO-galaxy pairs may not be typical of the majority of the narrow heavy-element QSO absorption systems, they provide a direct measure of column densities in the outer parts of galaxies and some limits on the relative abundances of the gas. Observations are presented here of the QSO S4 0248+430 and a nearby anonymous galaxy (Kuhr 1977). The 14 second separation of the line of sight to the QSO (z sub e = 1.316) and the z=0.052 spiral galaxy, (a projected separation of 20 kpc ((h sub o = 50, q sub o = 0)), makes this a particularly suitable pair for probing the extent and content of gas in the galaxy. Low resolution (6A full width half maximum), long slit charge coupled device (CCD) spectra show strong CA II H and K lines in absorption at the redshift of the galaxy (Junkkarinen 1987). Higher resolution spectra showing both Ca II H and K and Na I D1 and D2 in absorption and direct images are reported here.

  18. Enhanced photoluminescence due to two-photon enhanced three-photon absorption in Mn{sup 2+}-doped ZnS quantum dots

    SciTech Connect

    Subha, Radhu; Nalla, Venkatram; Ji, Wei; Feng, Xiaobo; Vijayan, C.

    2014-10-15

    In this work, we have investigated the multi-photon absorption induced photoluminescence in Mn{sup 2+}-doped ZnS quantum dots in the wavelength range 860 – 1050 nm (Near-Infrared Window I). The observed three-photon action cross-section has been compared with the theoretical prediction under four band approximation. An enhancement of four to five orders has been observed in the range from 970 to 1050 nm compared to the theoretical value, which is attributed to two-photon enhanced three-photon absorption. Transient lifetime measurements reveal a lifetime of 0.35 ± 0.3 ms, which is four to five orders higher than other conventional fluorescent probes.

  19. Bias in Dobson total ozone measurements at high latitudes due to approximations in calculations of ozone absorption coefficients and air mass

    NASA Astrophysics Data System (ADS)

    Bernhard, G.; Evans, R. D.; Labow, G. J.; Oltmans, S. J.

    2005-05-01

    The Dobson spectrophotometer is the primary standard instrument for ground-based measurements of total column ozone. The accuracy of its data depends on the knowledge of ozone absorption coefficients used for data reduction. We document an error in the calculations that led to the set of absorption coefficients currently recommended by the World Meteorological Organisation (WMO). This error has little effect because an empirical adjustment was applied to the original calculations before the coefficients were adopted by WMO. We provide evidence that this adjustment was physically sound. The coefficients recommended by WMO are applied in the Dobson network without correction for the temperature dependence of the ozone absorption cross sections. On the basis of data measured by Dobson numbers 80 and 82, which were operated by the National Oceanic and Atmospheric Administration (NOAA) Climate Monitoring and Diagnostics Laboratory at the South Pole, we find that omission of temperature corrections may lead to systematic errors in Dobson ozone data of up to 4%. The standard Dobson ozone retrieval method further assumes that the ozone layer is located at a fixed height. This approximation leads to errors in air mass calculations, which are particularly relevant at high latitudes where ozone measurements are performed at large solar zenith angles (SZA). At the South Pole, systematic errors caused by this approximation may exceed 2% for SZAs larger than 80°. The bias is largest when the vertical ozone distribution is distorted by the "ozone hole" and may lead to underestimation of total ozone by 4% at SZA = 85° (air mass 9). Dobson measurements at the South Pole were compared with ozone data from a collocated SUV-100 UV spectroradiometer and Version 8 overpass data from NASA's Total Ozone Mapping Spectrometer (TOMS). Uncorrected Dobson ozone values tend to be lower than data from the two other instruments when total ozone is below 170 Dobson units or SZAs are larger than

  20. Effects of thermophoresis and heat generation/absorption on MHD flow due to an oscillatory stretching sheet with chemically reactive species

    NASA Astrophysics Data System (ADS)

    Sheikh, Mariam; Abbas, Zaheer

    2015-12-01

    The effects of chemical reaction and heat generation/absorption on MHD flow over an oscillatory stretching surface in a viscous fluid have been studied in the presence of thermophoresis. The porous plate is oscillated back and forth in its own plane and suction/injection is also taking into account. The similarity solution of the developed non-linear governing partial differential equations is constructed in the form of series using homotopy analysis method. The convergence of the obtained series solutions is discussed in the whole domain (0 ≤ η ≤ ∞) . A parametric study of the all governing parameters is accomplished and the physical results are shown graphically.

  1. Impaired Intestinal Calcium Absorption in Protein 4.1R-deficient Mice Due to Altered Expression of Plasma Membrane Calcium ATPase 1b (PMCA1b)*

    PubMed Central

    Liu, Congrong; Weng, Haibao; Chen, Lixiang; Yang, Shaomin; Wang, Hua; Debnath, Gargi; Guo, Xinhua; Wu, Liancheng; Mohandas, Narla; An, Xiuli

    2013-01-01

    Protein 4.1R was first identified in the erythrocyte membrane skeleton. It is now known that the protein is expressed in a variety of epithelial cell lines and in the epithelia of many tissues, including the small intestine. However, the physiological function of 4.1R in the epithelial cells of the small intestine has not so far been explored. Here, we show that 4.1R knock-out mice exhibited a significantly impaired small intestinal calcium absorption that resulted in secondary hyperparathyroidism as evidenced by increased serum 1,25-(OH)2-vitamin D3 and parathyroid hormone levels, decreased serum calcium levels, hyperplasia of the parathyroid, and demineralization of the bones. 4.1R is located on the basolateral membrane of enterocytes, where it co-localizes with PMCA1b (plasma membrane calcium ATPase 1b). Expression of PMCA1b in enterocytes was decreased in 4.1−/− mice. 4.1R directly associated with PMCA1b, and the association involved the membrane-binding domain of 4.1R and the second intracellular loop and C terminus of PMCA1b. Our findings have enabled us to define a functional role for 4.1R in small intestinal calcium absorption through regulation of membrane expression of PMCA1b. PMID:23460639

  2. Enhanced squeezing by absorption

    NASA Astrophysics Data System (ADS)

    Grünwald, P.; Vogel, W.

    2016-04-01

    Absorption is usually expected to be detrimental to quantum coherence effects. However, there have been few studies into the situation for complex absorption spectra. We consider the resonance fluorescence of excitons in a semiconductor quantum well. The creation of excitons requires absorption of the incoming pump-laser light. Thus, the absorption spectrum of the medium acts as a spectral filter for the emitted light. Surprisingly, absorption can even improve quantum effects, as is demonstrated for the squeezing of the resonance fluorescence of the quantum-well system. This effect can be explained by an improved phase matching due to absorption.

  3. Photovoltaic enhancement due to surface-plasmon assisted visible-light absorption at the inartificial surface of lead zirconate-titanate film

    NASA Astrophysics Data System (ADS)

    Zheng, Fengang; Zhang, Peng; Wang, Xiaofeng; Huang, Wen; Zhang, Jinxing; Shen, Mingrong; Dong, Wen; Fang, Liang; Bai, Yongbin; Shen, Xiaoqing; Sun, Hua; Hao, Jianhua

    2014-02-01

    PZT film of 300 nm thickness was deposited on tin indium oxide (ITO) coated quartz by a sol-gel method. Four metal electrodes, such as Pt, Au, Cu and Ag, were used as top electrodes deposited on the same PZT film by sputtering at room temperature. In ITO-PZT-Ag and ITO-PZT-Au structures, the visible light (400-700 nm) can be absorbed partially by a PZT film, and the maximum efficiency of photoelectric conversion of the ITO-PZT-Ag structure was enhanced to 0.42% (100 mW cm-2, AM 1.5G), which is about 15 times higher than that of the ITO-PZT-Pt structure. Numerical simulations show that the natural random roughness of polycrystalline-PZT-metal interface can offer a possibility of coupling between the incident photons and SPs at the metal surface. The coincidence between the calculated SP properties and the measured EQE spectra reveals the SP origin of the photovoltaic enhancement in these ITO-PZT-metal structures, and the improved photocurrent output is caused by the enhanced optical absorption in the PZT region near the metal surface, rather than by the direct charge-transfer process between two materials.PZT film of 300 nm thickness was deposited on tin indium oxide (ITO) coated quartz by a sol-gel method. Four metal electrodes, such as Pt, Au, Cu and Ag, were used as top electrodes deposited on the same PZT film by sputtering at room temperature. In ITO-PZT-Ag and ITO-PZT-Au structures, the visible light (400-700 nm) can be absorbed partially by a PZT film, and the maximum efficiency of photoelectric conversion of the ITO-PZT-Ag structure was enhanced to 0.42% (100 mW cm-2, AM 1.5G), which is about 15 times higher than that of the ITO-PZT-Pt structure. Numerical simulations show that the natural random roughness of polycrystalline-PZT-metal interface can offer a possibility of coupling between the incident photons and SPs at the metal surface. The coincidence between the calculated SP properties and the measured EQE spectra reveals the SP origin of the

  4. Magneto-thermoelectric effects in the two-dimensional electron gas of a HgTe quantum well due to THz laser heating by cyclotron resonance absorption

    NASA Astrophysics Data System (ADS)

    Pakmehr, Mehdi; Bruene, Christoph; Buhmann, Hartmut; Molenkamp, Laurens; McCombe, Bruce

    2015-03-01

    HgTe quantum wells (QWs) have shown a number of interesting phenomena over the past 20 years, most recently the first two-dimensional topological insulating state. We have studied thermoelectric photovoltages of 2D electrons in a 6.1 nm wide HgTe quantum well induced by cyclotron resonance absorption (B = 2 - 5 T) of a focused THz laser beam. We have estimated thermo-power coefficients by detailed analysis of the beam profile at the sample surface and the photovoltage signals developed across various contacts of a large Hall bar structure at a bath temperature of 1.6 K. We obtain reasonable values of the magneto-thermopower coefficients. Work at UB was supported by NSF DMR 1008138 and the Office of the Provost, and at the University of Wuerzburg by DARPA MESO Contract N6601-11-1-4105, by DFG Grant HA5893/4-1 within SPP 1666 and the Leibnitz Program, and the EU ERC-AG Program (Project 3-TOP.

  5. Photovoltaic enhancement due to surface-plasmon assisted visible-light absorption at the inartificial surface of lead zirconate-titanate film.

    PubMed

    Zheng, Fengang; Zhang, Peng; Wang, Xiaofeng; Huang, Wen; Zhang, Jinxing; Shen, Mingrong; Dong, Wen; Fang, Liang; Bai, Yongbin; Shen, Xiaoqing; Sun, Hua; Hao, Jianhua

    2014-03-01

    PZT film of 300 nm thickness was deposited on tin indium oxide (ITO) coated quartz by a sol-gel method. Four metal electrodes, such as Pt, Au, Cu and Ag, were used as top electrodes deposited on the same PZT film by sputtering at room temperature. In ITO-PZT-Ag and ITO-PZT-Au structures, the visible light (400-700 nm) can be absorbed partially by a PZT film, and the maximum efficiency of photoelectric conversion of the ITO-PZT-Ag structure was enhanced to 0.42% (100 mW cm(-2), AM 1.5G), which is about 15 times higher than that of the ITO-PZT-Pt structure. Numerical simulations show that the natural random roughness of polycrystalline-PZT-metal interface can offer a possibility of coupling between the incident photons and SPs at the metal surface. The coincidence between the calculated SP properties and the measured EQE spectra reveals the SP origin of the photovoltaic enhancement in these ITO-PZT-metal structures, and the improved photocurrent output is caused by the enhanced optical absorption in the PZT region near the metal surface, rather than by the direct charge-transfer process between two materials. PMID:24477668

  6. Osteopetrorickets due to Snx10 Deficiency in Mice Results from Both Failed Osteoclast Activity and Loss of Gastric Acid-Dependent Calcium Absorption

    PubMed Central

    Ye, Liang; Morse, Leslie R.; Zhang, Li; Sasaki, Hajime; Mills, Jason C.; Odgren, Paul R.; Sibbel, Greg; Stanley, James R. L.; Wong, Gee; Zamarioli, Ariane; Battaglino, Ricardo A.

    2015-01-01

    Mutations in sorting nexin 10 (Snx10) have recently been found to account for roughly 4% of all human malignant osteopetrosis, some of them fatal. To study the disease pathogenesis, we investigated the expression of Snx10 and created mouse models in which Snx10 was knocked down globally or knocked out in osteoclasts. Endocytosis is severely defective in Snx10-deficent osteoclasts, as is extracellular acidification, ruffled border formation, and bone resorption. We also discovered that Snx10 is highly expressed in stomach epithelium, with mutations leading to high stomach pH and low calcium solubilization. Global Snx10-deficiency in mice results in a combined phenotype: osteopetrosis (due to osteoclast defect) and rickets (due to high stomach pH and low calcium availability, resulting in impaired bone mineralization). Osteopetrorickets, the paradoxical association of insufficient mineralization in the context of a positive total body calcium balance, is thought to occur due to the inability of the osteoclasts to maintain normal calcium–phosphorus homeostasis. However, osteoclast-specific Snx10 knockout had no effect on calcium balance, and therefore led to severe osteopetrosis without rickets. Moreover, supplementation with calcium gluconate rescued mice from the rachitic phenotype and dramatically extended life span in global Snx10-deficient mice, suggesting that this may be a life-saving component of the clinical approach to Snx10-dependent human osteopetrosis that has previously gone unrecognized. We conclude that tissue-specific effects of Snx10 mutation need to be considered in clinical approaches to this disease entity. Reliance solely on hematopoietic stem cell transplantation can leave hypocalcemia uncorrected with sometimes fatal consequences. These studies established an essential role for Snx10 in bone homeostasis and underscore the importance of gastric acidification in calcium uptake. PMID:25811986

  7. Comparison of whole-body specific absorption rate for human phantoms with and without skeletal features. Final report, 1 January-31 December 1985

    SciTech Connect

    Hurt, W.D.

    1986-05-01

    The most common biological effect of overexposure to radiofrequency radiation (RFR) fields may be described as an acute thermal burden. The extent of the effect depends primarily on the time rate of transfer of the energy to the biological specimen. The depth of penetration and the amount of incident energy absorbed varies as a function of the frequency of the incident radiation. As the frequency decreases, the penetration of energy into biological tissue becomes deeper; however, wavelengths in the kilohertz (kHz) and lower megahertz (MHz) regions are so long with respect to the physical dimensions of the human subject that energy absorption is negligible. The purpose of this research was to measure the energy absorption in human phantoms when exposed to high-frequency (HF) band fields.

  8. Specific features of the anisotropy of low-temperature microwave magnetoresistivity of lightly doped p-Ge due to the presence of light and heavy holes

    SciTech Connect

    Veinger, A. I. Zabrodskii, A. G.; Tisnek, T. V.; Goloshchapov, S. I.

    2011-10-15

    The microwave magnetoresistivity of lightly doped (nondegenerate) p-Ge has been studied by the electron spin resonance method. This technique can be employed to record the derivative of the microwave absorption with respect to the magnetic field on the assumption that changes in this absorption are proportional to changes in the conductivity of a semiconductor. At the 10-GHz frequency of the electromagnetic field, the averaging time of the effective masses of light and heavy holes at low temperatures is substantially longer than the oscillation period. This makes it possible to study the individual responses of light and heavy holes to the magnetic field. It is shown that the microwave magnetoabsorption associated with light holes only slightly depends on the direction of the magnetic field relative to the crystallographic axes of Ge. At the same time, the signal related to heavy holes changes by several times when a sample is rotated in a magnetic field. The experimental results are correlated with the theory of the classical magnetoresistive effect.

  9. CAN GROUND-BASED TELESCOPES DETECT THE OXYGEN 1.27 {mu}m ABSORPTION FEATURE AS A BIOMARKER IN EXOPLANETS?

    SciTech Connect

    Kawahara, Hajime; Matsuo, Taro; Takami, Michihiro; Fujii, Yuka; Kotani, Takayuki; Tamura, Motohide; Murakami, Naoshi; Guyon, Olivier

    2012-10-10

    The oxygen absorption line imprinted in the scattered light from Earth-like planets has been considered the most promising metabolic biomarker for exolife. We examine the feasibility of the detection of the 1.27 {mu}m oxygen band from habitable exoplanets, in particular, around late-type stars observed with a future instrument on a 30 m class ground-based telescope. We analyzed the night airglow around 1.27 {mu}m with the IRCS/echelle spectrometer on Subaru and found that the strong telluric emission from atmospheric oxygen molecules declines by an order of magnitude by midnight. By compiling nearby star catalogs combined with the sky background model, we estimate the detectability of the oxygen absorption band from an Earth twin, if it exists, around nearby stars. We find that the most dominant source of photon noise for the oxygen 1.27 {mu}m band detection comes from the night airglow if the contribution of the stellar point-spread function (PSF) halo is suppressed enough to detect the planet. We conclude that the future detectors, for which the detection contrast is limited by photon noise, can detect the oxygen 1.27 {mu}m absorption band of Earth twins for {approx}50 candidates of the late-type star. This paper demonstrates the importance of deploying a small inner working angle as an efficient coronagraph and extreme adaptive optics on extremely large telescopes, and clearly shows that doing so will enable the study of potentially habitable planets.

  10. Effect of prenatal lead toxicity on surface ultrastructural features, elemental composition and infrared absorption characteristics of the skin of albino mice.

    PubMed

    Dey, S; Arjun, J; Das, M; Bhattacharjee, C R; Dkhar, P S

    2001-01-01

    The epidermis and dermis of albino mice born to females receiving oral sublethal doses of lead during pregnancy developed several abnormalities. These included perforations, tissue damage, cell deformity, and disordered organization of collagen bundles, as revealed by scanning electron microscopy. An increase in the concentrations of zinc, iron, magnesium, calcium and a decrease in that of copper was evident from atomic absorption spectroscopical analysis, when entire skin tissues were examined. Infrared spectroscopy revealed the occurrence of split bands in the spectra at 1,200-1,000 cm(-1), suggesting a reduction in the symmetry of the sulphate group (glycosaminoglycans) of skin probably caused by covalent bonding of it with lead. PMID:11545451

  11. CONFIRMATION OF ENHANCED DWARF-SENSITIVE ABSORPTION FEATURES IN THE SPECTRA OF MASSIVE ELLIPTICAL GALAXIES: FURTHER EVIDENCE FOR A NON-UNIVERSAL INITIAL MASS FUNCTION

    SciTech Connect

    Van Dokkum, Pieter G.; Conroy, Charlie

    2011-07-01

    We recently found that massive cluster elliptical galaxies have strong Na I {lambda}8183, 8195 and FeH {lambda}9916 Wing-Ford band absorption, indicating the presence of a very large population of stars with masses {approx}< 0.3 M{sub sun}. Here we test this result by comparing the elliptical galaxy spectra to those of luminous globular clusters associated with M31. These globular clusters have similar metallicities, abundance ratios, and ages as massive elliptical galaxies but their low dynamical mass-to-light ratios rule out steep stellar initial mass functions (IMFs). From high-quality Keck spectra we find that the dwarf-sensitive absorption lines in globular clusters are significantly weaker than in elliptical galaxies and consistent with normal IMFs. The differences in the Na I and Wing-Ford indices are 0.027 {+-} 0.007 mag and 0.017 {+-} 0.006 mag, respectively. We directly compare the two classes of objects by subtracting the averaged globular cluster spectrum from the averaged elliptical galaxy spectrum. The difference spectrum is well fit by the difference between a stellar population synthesis model with a bottom-heavy IMF and one with a bottom-light IMF. We speculate that the slope of the IMF may vary with velocity dispersion, although it is not yet clear what physical mechanism would be responsible for such a relation.

  12. Methimazole-Induced Chronic Arthritis; Bilateral Gynecomastia Associated with the Combination of Methylphenidate and Paroxetine; Adrenal Suppression and Cushingoid Features with Inhaled Fluticasone; Pulmonary Thromboembolism Due to Paliperidone

    PubMed Central

    Mancano, Michael A.

    2014-01-01

    The purpose of this feature is to heighten awareness of specific adverse drug reactions (ADRs), discuss methods of prevention, and promote reporting of ADRs to the US Food and Drug Administration’s (FDA’s) Med Watch program (800-FDA-1088). If you have reported an interesting, preventable ADR to Med Watch, please consider sharing the account with our readers. Write to Dr. Mancano at ISMP, 200 Lakeside Drive, Suite 200, Horsham, PA 19044 (phone: 215-707-4936; e-mail: mmancano@temple.edu). Your report will be published anonymously unless otherwise requested. This feature is provided by the Institute for Safe Medication Practices (ISMP) in cooperation with the FDA’s Med Watch program and Temple University School of Pharmacy. ISMP is an FDA Med Watch partner. PMID:25477609

  13. Progression of neuropsychiatric and cognitive features due to exons 2 to 5 deletion in the epsilon-sarcoglycan gene: a case report.

    PubMed

    Multani, Namita; Moro, Elena; Lang, Anthony; Zurowski, Mateusz; Duff Canning, Sarah; Tartaglia, Maria Carmela

    2016-01-01

    Physical symptoms of myoclonus dystonia due to epsilon-sarcoglycan mutations are well documented; however, the progression of neuropsychiatric and cognitive symptoms remains unclear. We present a case of a 34-year-old woman with early childhood onset of myoclonic jerks, dystonic posture and developmental delay due to exons 2 to 5 deletion in the epsilon-sarcoglycan gene. Over time, she developed neuropsychiatric symptoms. She underwent bilateral deep brain stimulation of the ventral intermediate nucleus of the thalamus for her motor symptoms, which greatly improved but she exhibited slow deterioration of her neuropsychiatric and cognitive symptoms, particularly apathy, aggression and severe executive dysfunction. PMID:26652670

  14. Clinical features and molecular analysis of the α thalassemia/mental retardation syndromes. 1. Cases due to deletions involving chromosome band 16p13.3

    PubMed Central

    Wilkie, A. O. M.; Buckle, V. J.; Harris, P. C.; Lamb, J.; Barton, N. J.; Reeders, S. T.; Lindenbaum, R. H.; Nicholls, R. D.; Barrow, M.; Bethlenfalvay, N. C.; Hutz, M. H.; Tolmie, J. L.; Weatherall, D. J.; Higgs, D. R.

    1990-01-01

    We describe eight patients who have α thalassemia which cannot be accounted for by the Mendelian inheritance of abnormal α globin genes. Apart from the hematologic abnormality, the other universal clinical finding is mild to moderate mental handicap; there is also a broad spectrum of associated dysmorphic features. Initial analysis of the α globin gene complex (which maps to chromosome band 16p13.3), demonstrated that the α thalassemia results from failure of the patient to inherit an α globin allele from one of the parents. Using a combined molecular and cytogenetic approach, we have extended this analysis to show that all of these patients have 16p deletions which are variable in extent but limited to the terminal band 16p13.3; in at least four cases the deletion results from unbalanced chromosome translocation, and hence aneuploidy of a second chromosome is also present. The relatively nonspecific clinical phenotype contrasts with the other currently known microdeletion syndromes; this may reflect ascertainment bias in the recognition of such syndromes. This work represents the first step in the characterization of a new microdeletion syndrome that is probably underdiagnosed at present. Imagesp[1116]-aFigure 1Figure 3Figure 5 PMID:2339704

  15. Extreme Variability in a Broad Absorption Line Quasar

    NASA Astrophysics Data System (ADS)

    Stern, Daniel; Graham, Matthew; Arav, Nahum; Djorgovski, Stanislav G.; Chamberlain, Carter; Barth, Aaron J.; Donalek, Ciro; Drake, Andrew J.; Glikman, Eilat; Jun, Hyunsung David; Mahabal, Ashish A.; Steidel, Charles C.

    2016-01-01

    We report on extreme spectral variability seen in a broad absorption line quasar over the past decade, initially identified from the Catalina Real-time Transient Survey (CRTS). Photometrically, the source had a visual magnitude of V = 17.3 between 2002 and 2008. Then, over the following 5 years, the source slowly brightened by approximately one magnitude, to V = 16.2. A combination of archival and newly acquired spectra reveal the source to be an iron low-ionization broad absorption line (Fe-LoBAL) quasar with extreme changes in its absorption spectrum. Some absorption features completely disappear over the 9 years of optical spectra, while other features remain essentially unchanged. Absorption systems separated by several 1000 km/s in velocity show coordinated changes in the depths of their troughs, correlated with the flux changes. Therefore, we interpret the variability in the absorption troughs to be due to changes in photoionization, rather than due to motion of material into our line of sight. This source highlights the sort of rare transition objects that astronomy will now be finding through dedicated time domain surveys.

  16. Cholesterol absorption.

    PubMed

    Ostlund, Richard E

    2002-03-01

    Cholesterol absorption is a key regulatory point in human lipid metabolism because it determines the amount of endogenous biliary as well as dietary cholesterol that is retained, thereby influencing whole body cholesterol balance. Plant sterols (phytosterols) and the drug ezetimibe reduce cholesterol absorption and low-density lipoprotein cholesterol in clinical trials, complementing the statin drugs, which inhibit cholesterol biosynthesis. The mechanism of cholesterol absorption is not completely known but involves the genes ABC1, ABCG5, and ABCG8, which are members of the ATP-binding cassette protein family and appear to remove unwanted cholesterol and phytosterols from the enterocyte. ABC1 is upregulated by the liver X (LXR) and retinoid X (RXR) nuclear receptors. Acylcholesterol acytransferase-2 is an intestinal enzyme that esterifies absorbed cholesterol and increases cholesterol absorption when dietary intake is high. New clinical treatments based on better understanding of absorption physiology are likely to substantially improve clinical cholesterol management in the future. PMID:17033296

  17. Methane overtone absorption by intracavity laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Obrien, James J.

    1990-01-01

    Interpretation of planetary methane (CH4) visible-near IR spectra, used to develop models of planetary atmospheres, has been hampered by a lack of suitable laboratory spectroscopic data. The particular CH4 spectral bands are due to intrinsically weak, high overtone-combination transitions too complex for classical spectroscopic analysis. The traditional multipass cell approach to measuring spectra of weakly absorbing species is insufficiently sensitive to yield reliable results for some of the weakest CH4 absorption features and is difficult to apply at the temperatures of the planetary environments. A time modulated form of intracavity laser spectroscopy (ILS), has been shown to provide effective absorption pathlengths of 100 to 200 km with sample cells less than 1 m long. The optical physics governing this technique and the experimental parameters important for obtaining reliable, quantitative results are now well understood. Quantitative data for CH4 absorption obtained by ILS have been reported recently. Illustrative ILS data for CH4 absorption in the 619.7 nm and 681.9 nm bands are presented. New ILS facilities at UM-St. Louis will be used to measure CH4 absorption in the 700 to 1000 nm region under conditions appropriate to the planetary atmospheres.

  18. Generalized Landauer equation: absorption-controlled diffusion processes.

    PubMed

    Godoy, S; García-Colín, L S; Micenmacher, V

    1999-05-01

    The exact expression of the one-dimensional Boltzmann multiple-scattering coefficients, for the passage of particles through a slab of a given material, is obtained in terms of the single-scattering cross section of the material, including absorption. The remarkable feature of the result is that for multiple scattering in a metal, free from absorption, one recovers the well-known Landauer result for conduction electrons. In the case of particles, such as neutrons, moving through a weak absorbing media, Landuer's formula is modified due to the absorption cross section. For photons, in a strong absorbing media, one recovers the Lambert-Beer equation. In this latter case one may therefore speak of absorption-controlled diffusive processes. PMID:11969603

  19. Broadband perfect absorption of ultrathin conductive films with coherent illumination: Superabsorption of microwave radiation

    NASA Astrophysics Data System (ADS)

    Li, Sucheng; Luo, Jie; Anwar, Shahzad; Li, Shuo; Lu, Weixin; Hang, Zhi Hong; Lai, Yun; Hou, Bo; Shen, Mingrong; Wang, Chinhua

    2015-06-01

    Absorption of microwaves by metallic conductors is typically inefficient, albeit naturally broadband, due to the huge impedance mismatch between metal and free space. Reducing metal to ultrathin profile may improve absorption efficiency, but a maximal 50% absorption limit induced by the field continuity exists. Here, we experimentally show that broadband, perfect (100%) absorption of microwaves can be realized in a single layer of ultrathin conductive film when illuminated coherently by two oppositely directed incident beams. Our experiments keep the field continuity and simultaneously break the 50% limit. Inheriting the intrinsic broadband feature of metals, complete absorption is observed to be frequency independent in microwave experiments from 6 to 18 GHz. Remarkably, this occurs in films with thicknesses that are at the extreme subwavelength scales, ˜λ /10 000 or less. Our work proposes a way to achieve total electromagnetic wave absorption in an ultrawide spectrum of radio waves and microwaves with a simple conductive film.

  20. The clinical features of Ehlers-Danlos syndrome type VII due to a deletion of 24 amino acids from the pro alpha 1(I) chain of type I procollagen.

    PubMed Central

    Cole, W G; Evans, R; Sillence, D O

    1987-01-01

    The clinical features and progress of a child with the type VII form of Ehlers-Danlos syndrome due to a deletion in the pro alpha 1(I) of type I procollagen were studied. The child was born with bilateral dislocations of hips and knees and all other joints were markedly hypermobile. Persistent severe joint instability was the major clinical abnormality. She had a depressed nasal bridge with prominent paranasal folds and deeply set eyes with mild hypertelorism and micrognathia. The skin was soft, moderately hyperelastic, and sagged over the face and knees. Skin fragility and easy bruising appeared when she started walking. Electron microscopy of the dermis showed irregular collagen fibrils. Images PMID:3430546

  1. Lipids: Absorption and transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to the hydrophobic nature of lipids, dietary fat is handled differently than protein or carbohydrate with respect with digestion and absorption. Dietary fats are broken down throughout the gastrointestinal system. A unique group of enzymes and cofactors allows this process to proceed in an eff...

  2. Estimation of the spring wheat water and chlorophyll content in rainfed agriculture areas of the Loess Plateau based on the spectral absorption feature of the liquid water and chlorophyll

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoping; Guo, Ni; Zhang, Kai; Zhao, Hong

    2008-10-01

    Because of the high water content of vegetation, water absorption feature dominate spectral reflectance of vegetation in the near-infrared region of the spectrum, and chlorophyll dominate the visible region. Previous studies have primarily related water band indices (WI) to vegetation water content. But the similar studies are vacancy in Rained Agriculture Areas of Loess. Two observation tests were carried out in arid and semi-arid area in Loess Plateau in order to find out the best preferential sensitively spectral index to water content and chlorophyll for the spring wheat and to monitor crops drought in this area. The results indicated that at leaf level the NDVI and EVI are the highest sensitive indices to the FMC and Chlorophyll, and for the leaf EWT, SAVI is the best index((r=0.738,P<0.01)) at canopy level, the red edge (λred) and the water content have the best relationship, and the sensitivity for WI1180 and NDWI are better. And the λred is also the best indictor for the chlorophyll at canopy level, the second is R670/R440, Furthmore, If considered the potential for atmospheric interference when data are collected from aircraft or satellite plarforms, So WI1180, WI1450 and NDWI may be the feasible for satellite remote sensing of vegetation water content at the canopy level. Meanwhile the NDVI and EVI may be the best index for satellite remote sensing of vegetation water content at leaf level for the arid and semiarid Rainfed Agriculture Areas of Loess Plateau.

  3. Excellent microwave absorption property of Graphene-coated Fe nanocomposites

    PubMed Central

    Zhao, Xingchen; Zhang, Zhengming; Wang, Liaoyu; Xi, Kai; Cao, Qingqi; Wang, Dunhui; Yang, Yi; Du, Youwei

    2013-01-01

    Graphene has evoked extensive interests for its abundant physical properties and potential applications. It is reported that the interfacial electronic interaction between metal and graphene would give rise to charge transfer and change the electronic properties of graphene, leading to some novel electrical and magnetic properties in metal-graphene heterostructure. In addition, large specific surface area, low density and high chemical stability make graphene act as an ideal coating material. Taking full advantage of the aforementioned features of graphene, we synthesized graphene-coated Fe nanocomposites for the first time and investigated their microwave absorption properties. Due to the charge transfer at Fe-graphene interface in Fe/G, the nanocomposites show distinct dielectric properties, which result in excellent microwave absorption performance in a wide frequency range. This work provides a novel approach for exploring high-performance microwave absorption material as well as expands the application field of graphene-based materials. PMID:24305606

  4. ABSORPTION ANALYZER

    DOEpatents

    Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

    1961-11-14

    A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

  5. Visible absorption spectrum of liquid ethylene

    PubMed Central

    Nelson, Edward T.; Patel, C. Kumar N.

    1981-01-01

    The visible absorption spectrum of liquid ethylene at ≈ 108 K from 5500 Å to 7200 Å was measured by using a pulsed tunable dye laser, immersed-transducer, gated-detection opto-acoustic spectroscopy technique. The absorption features show the strongest band with an absorption coefficient of ≈2 × 10-2 cm-1 and the weakest band with an absorption coefficient of ≈1 × 10-4 cm-1. Proposed assignments of the observed absorption peaks involve combinations of overtones of local and normal modes of vibration of ethylene. PMID:16592978

  6. Detectability of cold streams into high-redshift galaxies by absorption lines

    NASA Astrophysics Data System (ADS)

    Goerdt, Tobias; Dekel, Avishai; Sternberg, Amiel; Gnat, Orly; Ceverino, Daniel

    2012-08-01

    Cold gas streaming along the dark matter filaments of the cosmic web is predicted to be the major source of fuel for disc buildup, violent disc instability and star formation in massive galaxies at high redshift. We investigate to what extent such cold gas is detectable in the extended circumgalactic environment of galaxies via Lyα absorption and selected low-ionization metal absorption lines. We model the expected absorption signatures using high-resolution zoom-in adaptive mesh refinement cosmological simulations. In the post-processing, we distinguish between self-shielded gas and unshielded gas. In the self-shielded gas, which is optically thick to Lyman continuum radiation, we assume pure collisional ionization for species with an ionization potential greater than 13.6 eV. In the optically-thin, unshielded gas, these species are also photoionized by the metagalactic radiation. In addition to absorption of radiation from background quasars, we compute the absorption line profiles of radiation emitted by the galaxy at the centre of the same halo. We predict the strength of the absorption signal for individual galaxies without stacking. We find that the Lyα absorption profiles produced by the streams are consistent with observations of absorption and emission Lyα profiles in high-redshift galaxies. Due to the low metallicities in the streams, and their low covering factors, the metal absorption features are weak and difficult to detect.

  7. Cloud absorption radiometer

    NASA Technical Reports Server (NTRS)

    Strange, M. G.

    1988-01-01

    The Cloud Absorption Radiometer (CAR) was developed to measure spectrally how light is scattered by clouds and to determine the single scattering albedo, important to meteorology and climate studies, with unprecedented accuracy. This measurement is based on ratios of downwelling to upwelling radiation within clouds, and so is not strongly dependent upon absolute radiometric calibration of the instrument. The CAR has a 5-inch aperture and 1 degree IFOV, and spatially scans in a plane orthogonal to the flight vector from the zenith to nadir at 1.7 revolutions per second. Incoming light is measured in 13 spectral bands, using silicon, germanium, and indium-antimonide detectors. Data from each channel is digitally recorded in flight with 10-bit (0.1 percent) resolution. The instrument incorporates several novel features. These features are briefly detailed.

  8. Gastrointestinal citrate absorption in nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Fegan, J.; Khan, R.; Poindexter, J.; Pak, C. Y.

    1992-01-01

    Gastrointestinal absorption of citrate was measured in stone patients with idiopathic hypocitraturia to determine if citrate malabsorption could account for low urinary citrate. Citrate absorption was measured directly from recovery of orally administered potassium citrate (40 mEq.) in the intestinal lavage fluid, using an intestinal washout technique. In 7 stone patients citrate absorption, serum citrate levels, peak citrate concentration in serum and area under the curve were not significantly different from those of 7 normal subjects. Citrate absorption was rapid and efficient in both groups, with 96 to 98% absorbed within 3 hours. The absorption of citrate was less efficient from a tablet preparation of potassium citrate than from a liquid preparation, probably due to a delayed release of citrate from wax matrix. However, citrate absorption from solid potassium citrate was still high at 91%, compared to 98% for a liquid preparation. Thus, hypocitraturia is unlikely to be due to an impaired gastrointestinal absorption of citrate in stone patients without overt bowel disease.

  9. Simultaneous infrared and UV-visible absorption spectra of matrix-isolated carbon vapor

    NASA Technical Reports Server (NTRS)

    Kurtz, Joe; Huffman, Donald R.

    1989-01-01

    Carbon molecules were suggested as possible carriers of the diffuse interstellar bands. In particular, it was proposed that the 443 nm diffuse interstellar band is due to the same molecule which gives rise to the 447 nm absorption feature in argon matrix-isolated carbon vapor. If so, then an associated C-C stretching mode should be seen in the IR. By doing spectroscopy in both the IR and UV-visible regions on the same sample, the present work provides evidence for correlating UV-visible absorption features with those found in the IR. Early data indicates no correlation between the strongest IR feature (1997/cm) and the 447 nm band. Correlation with weaker IR features is being investigated.

  10. Asymmetry in the winter-anomalous behaviour of absorption at midlatitudes in the Northern and Southern Hemispheres

    NASA Astrophysics Data System (ADS)

    Schwentek, H.; Elling, W.; Peres, M.

    1980-06-01

    Ionospheric absorption data at 1.73 and 2.28 MHz were obtained during a winter at Lindau (51.6 deg N) and Ushuaia (54.8 deg S). These data are compared in order to detect a possible asymmetry in the behavior of the ionospheric absorption in the Northern and Southern Hemispheres. A real asymmetry was found, mainly in the features of excess winter-anomalous absorption. It is suggested that this asymmetry is due to different meteorological processes in the two hemispheres around the mesopause region in winter.

  11. A reverberation room round robin on the determination of absorption coefficients

    NASA Astrophysics Data System (ADS)

    Kath, U.

    In ten reverberation rooms with very different volumes and different room shapes, the absorption coefficients for mineral fiber mat were measured. The particular feature of this round robin was that the absorption material was much thicker than in other similar experiments and that it was measured not only with an area of 12 sq m on the floor, but also as a complete surface covering of a small wall in order to avoid the edge effect. The decay curves were evaluated in at least two institutions and the absorption coefficients were calculated using the Eyring equation. The absorption coefficients were quite dispersed from one room to another and also from one-third octave band to the adjacent ones. Errors due to change are small, thus one is dealing with systematic errors.

  12. Ultraviolet absorption by interstellar gas at large distances from the galactic plane

    NASA Technical Reports Server (NTRS)

    Savage, B. D.; De Boer, K. S.

    1981-01-01

    Eighteen high-dispersion IUE spectra of six stars in the Large Magellanic Cloud, three stars in the Small Magellanic Cloud, and two foreground stars were analyzed. Fourteen spectra cover the wavelengths 1150-2000 A, and four cover 1900-3200 A; the velocity resolution is about 25 km/s. All the Magellanic Cloud spectra exhibit very strong interstellar absorption lines due to a wide range of ionization stages at galactic velocities and at velocities associated with the IMC or SMC. The observational results are related to current theoretical ideas about the origin and physical state of gaseous galactic halos; the analysis is restricted to the Milky Way absorption features.

  13. Measurements of trace constituents from atmospheric infrared emission and absorption spectra, a feasibility study

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Williams, W. J.; Murcray, D. G.

    1974-01-01

    The feasibility of detecting eight trace constituents (CH4, HCl, HF, HNO3, NH3, NO, NO2 and SO2) against the rest of the atmospheric background at various altitudes from infrared emission and absorption atmospheric spectra was studied. Line-by-line calculations and observational data were used to establish features that can be observed in the atmospheric spectrum due to each trace constituent. Model calculations were made for experimental conditions which approximately represent state of the art emission and absorption spectrometers.

  14. Absorption modulation enhancement of Azo-polymer film induced by plasmonic field

    NASA Astrophysics Data System (ADS)

    Wang, Xiangxian; Zhang, Douguo; Fu, Qiang; Ming, Hai; Wu, Wenxuan; Zhang, Qijin

    2012-11-01

    A thin photochromic film on top of the resist layer can be used as a virtual mask to fabricate super-resolution lithography patterns. In this letter, based on the azobenzene polymer, the absorption intensity of the 365nm LED is effectively modulated by 532nm laser, the modulation degree reaches to 87%.When the silver nanocubes are dropped onto the surface of the polymer film, the modulation degree is significantly higher than that without the nanoparticles in the same intensity of 532nm laser due to the field enhancement of excitation of surface plasmons. The absorption modulation features of the polymer film are favorable for the further smaller line width nanolithography.

  15. An iron absorption model of gamma-ray burst spectra

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.; Kargatis, Vincent E.

    1994-01-01

    Most gamma-ray bursts (GRBs) exhibit deficits of X-rays below approximately 200 keV. Here we consider a spectral model in which the burst source is shielded by an optically thick layer of circumburster material (CBM) rich in iron-group elements whose photoelectric absorption opacity exceeds the Thomson opacity below approximately 120 keV. For power-law distributions of absorption depths along the lines of sight the absorbed spectrum can indeed mimic the typial GRB spectrum. This model predicts that (a) the spectrum should evolve monotonically from hard to soft during each energy release, which is observed in most bursts, especially in fast rise exponential decay bursts; (b) Fe spectral features near 7 keV may be present in some bursts; and (c) the ratio of burst distances to the CBM and to Earth should be approximately 10(exp -11) if the spectral evolution is purely due to Fe stripping by the photons.

  16. Inversion of instantaneous equivalent absorption coefficient and its application

    SciTech Connect

    Weihua, W. )

    1992-01-01

    Absorption coefficient is an important parameter for reservoir description. The major troubles in extracting absorption coefficient from seismic data are amplitude and waveform distortions; they greatly restrict the inversion which is based on reflection amplitude variation or reflection frequency variation. This paper presents a new method which avoids amplitude and uses waveform variation gradient in wave propagation to make the inversion of absorption coefficient. Apparent absorption coefficient and pseudo absorption coefficient are adopted so as to remove the influence which the waveform distortion due to thin bed tuning brings to absorption coefficient extraction. The final instantaneous equivalent absorption coefficient, a true absorption coefficient which reflects real absorptive character of a seismic medium, can be obtained by subtracting the pseudo absorption coefficient (inversely calculated using maximum entropy) from the apparent absorption coefficient the authors have calculated.

  17. Absorption heat pumps

    NASA Astrophysics Data System (ADS)

    Huhtinen, M.; Heikkilae, M.; Andersson, R.

    1987-03-01

    The aim of the study was to analyze the technical and economic feasibility of absorption heat pumps in Finland. The work was done as a case study: the technical and economic analyses have been carried out for six different cases, where in each the suitable size and type of the heat pump plant and the auxiliary components and connections were specified. The study also detailed the costs concerning the procurement, installation and test runs of the machinery, as well as the savings in energy costs incurred by the introduction of the plant. Conclusions were drawn of the economic viability of the applications studied. The following cases were analyzed: heat recovery from flue gases and productin of district heat in plants using peat, natural gas, and municipal wastes as a fuel. Heat recovery in the pulp and paper industry for the upgrading of pressure of secondary steam and for the heating of white liquor and combustion and drying the air. Heat recovery in a peat-fulled heat and power plant from flue gases that have been used for the drying of peat. According to the study, the absorption heat pump suits best to the production of district heat, when the heat source is the primary energy is steam produced by the boiler. Included in the flue as condensing is the purification of flue gases. Accordingly, benefit is gained on two levels in thick applications. In heat and power plants the use of absorption heat pumps is less economical, due to the fact that the steam used by the pump reduces the production of electricity, which is rated clearly higher than heat.

  18. Role of metallic absorption on enhancing the light emitting efficiency by plasmonic gratings

    NASA Astrophysics Data System (ADS)

    Gou, Yuchun; Xuan, Yimin

    2013-09-01

    Due to the adoption of the metallic materials in the surface-plasmon-based light emitting diodes (SP-LEDs), strong absorption of the metal can result in the dissipation of the most photons in the form of thermal energy. In order to investigate the role of the metallic absorption in the SP-LEDs, by means of a series of computational examples of our proposed structure, the effects of several features on the absorptivity of the metal and the light extraction efficiency (LEE) of the chips have been analyzed in detail. The results indicate that the chips with combined metallic and dielectric gratings can exhibit relatively the highest LEE, whereas the absorption of the metal in the chips is very strong, and the absorptivity is several times of LEE. It is concluded that to reduce the absorption and keep high light extraction, proper structure in which the odd mode of surface plasmons can be stimulated at the desired wavelength should be used. In addition, the hexagonal gratings show relatively larger light extraction enhancement and stronger absorption than the rectangular ones.

  19. Intracavity absorption line shape and the super-regen model

    NASA Astrophysics Data System (ADS)

    Lewellen, L. R.; Brink, G. O.

    1981-10-01

    Intracavity absorption has been observed in a short lived excited state of helium produced in an RF discharge inside the dye laser cavity. The line shape consists of an absorption feature with two symmetric enhancement wings. The central absorption feature is considerably broadened over the natural width, and this is shown to be in agreement with the superregen model. It is also shown that under certain conditions the ICA signal inverts so that the central feature becomes enhanced and the symmetric wings appear as absorption. This result is also in agreement with predictions of the model.

  20. Infra-red absorption lines by molecules in grain mantles

    NASA Astrophysics Data System (ADS)

    Hagen, W.; Allamandola, L. J.; Greenberg, J. M.

    1980-06-01

    The laboratory spectrum of a solid mixture of H2O, CO, CH3OH, and NH3 at a temperature of 10 K reproduces the shape and peak positions of interstellar features. It is shown that the broad absorption features evident in the MIR spectra of some astronomical objects associated with interstellar dust can be explained by absorptions of molecules in grain mantles.

  1. Effect of in-material losses on terahertz absorption, transmission, and reflection in photonic crystals made of polar dielectrics

    SciTech Connect

    Serebryannikov, Andriy E.; Nojima, S.; Alici, K. B.; Ozbay, Ekmel

    2015-10-07

    The effect of the material absorption factor on terahertz absorption (A), transmittance (T), and reflectance (R) for slabs of PhC that comprise rods made of GaAs, a polar dielectric, is studied. The main goal was to illustrate how critical a choice of the absorption factor for simulations is and to indicate the importance of the possible modification of the absorption ability by using either active or lossy impurities. The spectra of A, T, and R are strongly sensitive to the location of the polaritonic gap with respect to the photonic pass and stop bands connected with periodicity that enables the efficient combination of the effects of material and structural parameters. It will be shown that the spectra can strongly depend on the utilized value of the material absorption factor. In particular, both narrow and wide absorption bands may appear owing to a variation of the material parameters with a frequency in the vicinity of the polaritonic gap. The latter are often achieved at wideband suppression of transmission, so that an ultra-wide stop band can appear as a result of adjustment of the stop bands having different origin. The results obtained at simultaneous variation of the absorption factor and frequency, and angle of incidence and frequency, indicate the possibility of the existence of wide ranges of tolerance, in which the basic features do remain. This allows for mitigating the accuracy requirements for the absorption factor in simulations and promises the efficient absorption of nonmonochromatic waves and beams with a wide angular spectrum. Suppression of narrowband effects in transmission is demonstrated at rather large values of the absorption factor, when they appear due to either the defect modes related to structural defects or dispersion inspired variations of the material parameters in the vicinity of the polaritonic gap. Comparison with auxiliary structures helps one to detect the common features and differences of homogeneous slabs and slabs of a

  2. Narrow Absorption Components in Be Star Winds

    NASA Technical Reports Server (NTRS)

    Grady, C. A.

    1985-01-01

    The stars omega Ori (B2 IIIe), 66 Oph (B2 IVe), and 59 Cyg (B1.5 IVe) are discussed. The extent to which the narrow absorption components in these Be stars differs from narrow components in the O stars and gamma Cas is explored. Any models or mechanisms for the formation of narrow absorption features in the UV resonance lines of Be star spectra must account for the presence of multiple narrow absorption features which are variable in number, radial velocity, and strength. Models predicting a high and low density structure to the stellar wind caused by instabilities in a flow driven by radiation pressure or by variable mass loss may be more successful in describing the behavior of winds in early Be stars. These models appear to be capable of producing single absorption components in the velocity range observed for O stars and very early Be stars.

  3. Enhanced absorption cycle computer model

    NASA Astrophysics Data System (ADS)

    Grossman, G.; Wilk, M.

    1993-09-01

    Absorption heat pumps have received renewed and increasing attention in the past two decades. The rising cost of electricity has made the particular features of this heat-powered cycle attractive for both residential and industrial applications. Solar-powered absorption chillers, gas-fired domestic heat pumps, and waste-heat-powered industrial temperature boosters are a few of the applications recently subjected to intensive research and development. The absorption heat pump research community has begun to search for both advanced cycles in various multistage configurations and new working fluid combinations with potential for enhanced performance and reliability. The development of working absorption systems has created a need for reliable and effective system simulations. A computer code has been developed for simulation of absorption systems at steady state in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the system's components and property subroutines containing thermodynamic properties of the working fluids. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnections. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system, and the heat duty at each unit, from which the coefficient of performance (COP) may be determined. This report describes the code and its operation, including improvements introduced into the present version. Simulation results are described for LiBr-H2O triple-effect cycles, LiCl-H2O solar-powered open absorption cycles, and NH3-H2O single-effect and generator-absorber heat exchange cycles. An appendix contains the user's manual.

  4. OH 1.563 micron Absorption from Starspots on Active Stars

    NASA Astrophysics Data System (ADS)

    O'Neal, Douglas; Neff, James E.

    1997-03-01

    We present results from a study of starspots on active stars using a pair of vibrational-rotational absorption lines of the OH molecule near 1.563mu m. We detect excess OH absorption due to dark, cool starspots on the RS CVn binaries II Pegasi, V1762 Cygni, and lambda Andromedae. This is the first detection of OH absorption from spots on stars other than the Sun. We have measured absorption equivalent widths of these OH lines (which are blended at the resolution of our observations) in inactive giant and dwarf stars of spectral types G, K, and M. We find that the total equivalent width of the line pair increases approximately linearly as effective temperature decreases from 5000 K to 3000 K. This greatly extends the temperature range over which starspots can be detected through molecular absorption features. We measure starspot filling factors by fitting the spectra of active stars with linear combinations of comparison star spectra representing the spot and non-spot regions of the star. Fitting only one spectral feature, we cannot derive independent constraints on starspot area and temperature. Assuming spot temperatures based on previous analyses, we find (for one epoch) spot filling factors between 35% and 48% for II Peg, 22% and 26% for lambda And, and 27% and 32% for V1762 Cyg.

  5. On the statistics of quasar absorption lines

    NASA Astrophysics Data System (ADS)

    Zuiderwijk, E. J.

    1984-12-01

    The distribution of absorption lines in 13 quasar spectra is analyzed and shown to be fully consistent with the hypothesis of randomly, but not uniformly, distributed absorption features. The analysis by Libby et al. (1984), in which it is claimed that the number of wavelength coincidences among absorption lines in different quasar spectra (as measured in the rest frame of the quasars) is much larger than expected, implying absorbers in the quasars themselves, is totally invalid. Instead, the number of these coincidences is fully commensurate with the expected one on the assumption of randomness.

  6. Coherent Absorption of N00N States.

    PubMed

    Roger, Thomas; Restuccia, Sara; Lyons, Ashley; Giovannini, Daniel; Romero, Jacquiline; Jeffers, John; Padgett, Miles; Faccio, Daniele

    2016-07-01

    Recent results in deeply subwavelength thickness films demonstrate coherent control and logical gate operations with both classical and single-photon light sources. However, quantum processing and devices typically involve more than one photon and nontrivial input quantum states. Here we experimentally investigate two-photon N00N state coherent absorption in a multilayer graphene film. Depending on the N00N state input phase, it is possible to selectively choose between single- or two-photon absorption of the input state in the graphene film. These results demonstrate that coherent absorption in the quantum regime exhibits unique features, opening up applications in multiphoton spectroscopy and imaging. PMID:27447505

  7. Coherent Absorption of N00N States

    NASA Astrophysics Data System (ADS)

    Roger, Thomas; Restuccia, Sara; Lyons, Ashley; Giovannini, Daniel; Romero, Jacquiline; Jeffers, John; Padgett, Miles; Faccio, Daniele

    2016-07-01

    Recent results in deeply subwavelength thickness films demonstrate coherent control and logical gate operations with both classical and single-photon light sources. However, quantum processing and devices typically involve more than one photon and nontrivial input quantum states. Here we experimentally investigate two-photon N00N state coherent absorption in a multilayer graphene film. Depending on the N00N state input phase, it is possible to selectively choose between single- or two-photon absorption of the input state in the graphene film. These results demonstrate that coherent absorption in the quantum regime exhibits unique features, opening up applications in multiphoton spectroscopy and imaging.

  8. Influence of Sn{sup 4+} and Sn{sup 4+}/Mg{sup 2+} doping on structural features and visible absorption properties of {alpha}-Fe{sub 2}O{sub 3} hematite

    SciTech Connect

    Gaudon, M.; Pailhe, N.; Majimel, J.; Wattiaux, A.; Abel, J.; Demourgues, A.

    2010-09-15

    Pure, Sn-doped and Mg/Sn co-doped {alpha}-Fe{sub 2}O{sub 3} hematite samples were synthesized by precipitation process. Fe{sub 2}O{sub 3} is the most popular red mineral pigment which is used largely in traditional ceramics, tar and concrete. The compounds were characterized by powder X-ray diffraction (XRD), scanning transmission electronic microscopy (energy dispersive X-ray cartography), Moessbauer spectroscopy, magnetic investigations versus temperature and visible-NIR spectroscopy. Both {sup 57}Fe and {sup 119}Sn Moessbauer analyses combined with rietveld XRD refinements are the ideal techniques to characterize tin-iron oxides. Hence, thanks to these techniques it was shown how the synthesis temperature influences directly the grain size and the dopants concentration limit which can be incorporated into the host hematite matrix. The stabilization of these tetravalent and divalent dopants into the hematite framework leads to reduce the crystal growth and to limit the (AF) ordering due to the formation of cationic vacancies. The study of the Morin magnetic transition emphasizes this demonstration. In a second part, the influence of the dopants incorporation on the material color was investigated in order to show which key parameters allow improving the red color saturation of iron oxides. In order to improve the red color of the hematites, it was shown that the introduction of cationic vacancies-limiting the octahedral distortion thanks to the interruption of the dissymmetric metal-metal orbital coupling-is the key point. Vacancies are created by Sn{sup 4+}, doping for an increase of the introduced Sn{sup 4+} concentration; it acts to the detriment of the color saturation. - Graphical Abstract: Sn-doped or Sn/Mg-doped Fe{sub 2}O{sub 3} hematites, were analyzed by X-ray diffraction refinement, Moessbauer spectroscopy, magnetic characterization and TEM investigations. Their color is correlated to the doping ions concentration.

  9. Vibronic Structures in Absorption and Fluorescence Spectra of Firefly Oxyluciferin in Aqueous Solutions.

    PubMed

    Hiyama, Miyabi; Noguchi, Yoshifumi; Akiyama, Hidefumi; Yamada, Kenta; Koga, Nobuaki

    2015-01-01

    To elucidate the factors determining the spectral shapes and widths of the absorption and fluorescence spectra for keto and enol oxyluciferin and their conjugate bases in aqueous solutions, the intensities of vibronic transitions between their ground and first electronic excited states were calculated for the first time via estimation of the vibrational Franck-Condon factors. The major normal modes, overtones and combination tones in absorption and fluorescence spectra are similar for all species. The theoretical full widths at half maximum of absorption spectra are 0.4-0.7 eV and those for the fluorescence spectra are 0.4-0.5 eV, except for phenolate-keto that exhibits exceptionally sharp peak widths due to the dominance of the 0-0' or 0'-0 band. These spectral shapes and widths explain many relevant features of the experimentally observed spectra. PMID:25946599

  10. The Redshift-Dependence of Gamma-Ray Absorption in the Environments of Blazars

    SciTech Connect

    Reimer, A.; /Stanford U., HEPL /KIPAC, Menlo Park

    2011-11-21

    One of the key scientific objectives of the new generation high energy instruments is the quest for signatures from the extragalactic background light (EBL) at UV/optical/IR energies and its evolution by means of photon-photon absorption over extragalactic distances.I will discuss the various methods proposed, and biases that may be introduced when studying the evolution of the EBL with capable {gamma}-ray observatories like e.g. GLAST or CTA, where the {gamma}-ray horizon is probed by means of statistical analysis of absorption features in AGN spectra at various redshifts. In particular, the effect of the redshift-dependence of 'local opacity' in {gamma}-ray loud quasars due to possible {gamma}-ray absorption through photon-photon pair production of jet photons in the external photon environments (accretion disk, broad-line region radiation field) on evolutionary studies of the EBL is highlighted.

  11. Twin-peaks absorption spectra of excess electron in ionic liquids

    NASA Astrophysics Data System (ADS)

    Musat, Raluca M.; Kondoh, Takafumi; Yoshida, Yoichi; Takahashi, Kenji

    2014-07-01

    The solvated electron in room temperature ionic liquids (RTILs) has been the subject of several investigations and several reports exist on its nature and absorption spectrum. These studies concluded that the solvated electron exhibits an absorption spectrum peaking in the 1000-1400 nm region; a second absorption band peaking in the UV region has been assigned to the hole or dication radicals simultaneously formed in the system. Here we report on the fate of the excess electron in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, P14+/NTf2- using nanosecond pulse radiolysis. Scavenging experiments allowed us to record and disentangle the complex spectrum measured in P14+/NTf2-. We identified a bi-component absorption spectrum, due to the solvated electron, the absorption maxima located at 1080 nm and around 300 nm, as predicted by previous ab-initio molecular dynamics simulations for the dry excess electron. We also measured the spectra using different ionic liquids and confirmed the same feature of two absorption peaks. The present results have important implications for the characterization of solvated electrons in ionic liquids and better understanding of their structure and reactivity.

  12. One- and two-photon absorption of a spiropyran-merocyanine system: experimental and theoretical studies.

    PubMed

    Matczyszyn, Katarzyna; Olesiak-Banska, Joanna; Nakatani, Keitaro; Yu, Pei; Murugan, N Arul; Zaleśny, Robert; Roztoczyńska, Agnieszka; Bednarska, Joanna; Bartkowiak, Wojciech; Kongsted, Jacob; Ågren, Hans; Samoć, Marek

    2015-01-29

    We report on the nonlinear optical properties measurements and quantum-chemical calculations of a well-known photochromic system consisting of spiropyran and the merocyanine photoproduct. The study of nonlinear absorption and refraction properties of the molecules dissolved in chloroform were performed with the Z-scan technique, using femtosecond pulses in a wide range of wavelengths. Maxima in the two-photon absorption spectrum at 700 and 1050 nm were found for the merocyanine form, and the corresponding two-photon absorption cross section is 80 GM and 20 GM, respectively. The latter feature does not vanish completely in the nonlinear spectrum of the spiropyran form, possibly because of the existence of some photoconversion caused by the laser beam during the measurements. A nonlinear absorption peak at 900 nm is found in the spiropyran form with an effective cross section of about 20 GM; it is likely due to three-photon absorption or to absorption by some intermediate species. The experimental data are supported by calculations performed with the use of a hybrid quantum mechanics-molecular mechanics approach. PMID:25531561

  13. Feature engineering for drug name recognition in biomedical texts: feature conjunction and feature selection.

    PubMed

    Liu, Shengyu; Tang, Buzhou; Chen, Qingcai; Wang, Xiaolong; Fan, Xiaoming

    2015-01-01

    Drug name recognition (DNR) is a critical step for drug information extraction. Machine learning-based methods have been widely used for DNR with various types of features such as part-of-speech, word shape, and dictionary feature. Features used in current machine learning-based methods are usually singleton features which may be due to explosive features and a large number of noisy features when singleton features are combined into conjunction features. However, singleton features that can only capture one linguistic characteristic of a word are not sufficient to describe the information for DNR when multiple characteristics should be considered. In this study, we explore feature conjunction and feature selection for DNR, which have never been reported. We intuitively select 8 types of singleton features and combine them into conjunction features in two ways. Then, Chi-square, mutual information, and information gain are used to mine effective features. Experimental results show that feature conjunction and feature selection can improve the performance of the DNR system with a moderate number of features and our DNR system significantly outperforms the best system in the DDIExtraction 2013 challenge. PMID:25861377

  14. Discerning Spectral Features in L Dwarfs

    NASA Astrophysics Data System (ADS)

    Nunez, Alejandro; Cruz, K.; Burgasser, A. J.; Kirkpatrick, J. D.; Reid, I. N.

    2011-01-01

    Brown dwarfs are star-like objects that, due to their very low masses (less than 75 Jupiter masses,) never reach the main sequence, and instead cool with time. This cooling leads to a breakdown of the relationship between temperature and mass that exists for stars. Therefore, brown dwarfs with similar temperatures (as indicated by spectral type) could have very different masses and ages. We are investigating the near-infrared spectra of L dwarfs with the same optically derived spectral types (implying similar effective temperatures) with the goal of distinguishing subtle differences, patterns, and/or correlations among absorption features that could reveal information about their ages and masses. Our sample consists of 43 L0-L8 dwarfs with both optical and near-infrared spectra, thus covering the 0.65 to 2.4-micron range. Our analysis included objects with either "typical” or peculiar spectra. Some of the objects with peculiar spectra are suspected low-gravity/young and blue/low-metallicity dwarfs. For each optical type, we normalized and overplotted the spectra in four bands separately: Optical, J, H, and K band. Each resulting plot was examined by eye to look for subtle differences in spectral absorption features, likely due to age and mass. We present the preliminary results from this detailed spectral analysis. In particular, our analysis reveals the major spectral differences in the near infrared of both "red” and "blue” L dwarfs. This work was funded by the RISE Grant GM R25 6066, and we acknowledge the hospitality of the American Museum of Natural History.

  15. Saturnian trapped radiation and its absorption by satellites and rings: the first results from pioneer 11.

    PubMed

    Simpson, J A; Bastian, T S; Chenette, D L; Lentz, G A; McKibben, R B; Pyle, K R; Tuzzolino, A J

    1980-01-25

    Electrons and protons accelerated and trapped in a Saturnian magnetic field have been found by the University of Chicago experiments on Pioneer 11 within 20 Saturn radii (Rs) of the planet. In the innermost regions, strong absorption effects due to satellites and ring material were observed, and from approximately 4 Rs inwards to the outer edge of the A ring at 2.30 Rs (where the radiation is absorbed), the intensity distributions of protons (>/= 0.5 million electron volts) and electrons (2 to 20 million electron volts) were axially symmetric, consistent with a centered dipole aligned with the planetary rotation axis. The maximum fluxes observed for protons (> 35 million electron volts and for electrons < 3.4 million electron volts) were 3 x 10(4) and 3 x 10(6) per square centimeter per second, respectively. Absorption of radiation by Mimas provides a means of estimating the radial diffusion coefficient for charged particle transport. However, the rapid flux increases observed between absorption features raise new questions concerning the physics of charged particle transport and acceleration. An absorption feature near 2.5 Rs has led to the discovery of a previously unknown satellite with a diameter of approximately 200 kilometers, semimajor axis of 2.51 Rs, and eccentricity of 0.013. Radiation absorption features that suggest a nonuniform distribution of matter around Saturn have also been found from 2.34 to 2.36 Rs, near the position of the F ring discovered by the Pioneer imaging experiment. Beneath the A, B, and C rings we continued to observe a low flux of high-energy electrons. We conclude that the inner Saturn magnetosphere, because of its near-axial symmetry and the many discrete radiation absorption regions, offers a unique opportunity to study the acceleration and transport of charged particles in a planetary magnetic field. PMID:17833550

  16. New Dust Features Observed with ISO

    NASA Technical Reports Server (NTRS)

    Tielens, Alexander G. G. M.; Young, Richard E. (Technical Monitor)

    1997-01-01

    This paper will review our current knowledge of circumstellar and interstellar dust with the emphasis on infrared spectroscopy with ISO. Objects embedded in or located behind molecular clouds show a wealth of absorption features due to simple molecules in an icy mantle. The SWS on ISO has provided us, for the first time, with complete 3-45 um spectra which allow an inventory of interstellar ice. Among the species identified are H2O, CH3OH, CH4, CO2, CO, and OCS. These species are formed through simple reactions among gas phase species accreted on grain surfaces, possibly modified by FUV photolysis and warm-up (ie., outgassing). The implications of the observations for our understanding of these processes will be reviewed. The IR spectra of many UV bright objects are dominated by strong emission features at 3.3, 6.2, 7.7, and 11.3 micrometers. These are generally attributed to Polycyclic Aromatic Hydrocarbons (PAHs) molecules. The observational evidence will be reviewed. The emphasis will be on recent data which show widespread spectral variations, particularly among protoplanetary and planetary nebulae, and their implications. One of the most exciting, recent discoveries on interstellar and circumstellar dust has been the detection of spectral structure due to crystalline olivine and enstatite in a variety of objects surrounded by circumstellar silicates. These spectra will be reviewed and circumstellar silicate mineralogy will be discussed.

  17. General features

    SciTech Connect

    Wallace, R.E.

    1990-01-01

    The San Andreas fault system, a complex of faults that display predominantly large-scale strike slip, is part of an even more complex system of faults, isolated segments of the East Pacific Rise, and scraps of plates lying east of the East Pacific Rise that collectively separate the North American plate from the Pacific plate. This chapter briefly describes the San Andreas fault system, its setting along the Pacific Ocean margin of North America, its extent, and the patterns of faulting. Only selected characteristics are described, and many features are left for depictions on maps and figures.

  18. A Study of Carbon Features in Type Ia Supernova Spectra

    NASA Astrophysics Data System (ADS)

    Parrent, Jerod T.; Thomas, R. C.; Fesen, Robert A.; Marion, G. H.; Challis, Peter; Garnavich, Peter M.; Milisavljevic, Dan; Vinkò, Jòzsef; Wheeler, J. Craig

    2011-05-01

    One of the major differences between various explosion scenarios of Type Ia supernovae (SNe Ia) is the remaining amount of unburned (C+O) material and its velocity distribution within the expanding ejecta. While oxygen absorption features are not uncommon in the spectra of SNe Ia before maximum light, the presence of strong carbon absorption has been reported only in a minority of objects, typically during the pre-maximum phase. The reported low frequency of carbon detections may be due to low signal-to-noise data, low abundance of unburned material, line blending between C II λ6580 and Si II λ6355, ejecta temperature differences, asymmetrical distribution effects, or a combination of these. However, a survey of published pre-maximum spectra reveals that more SNe Ia than previously thought may exhibit C II λ6580 absorption features and relics of line blending near ~6300 Å. Here we present new SN Ia observations where spectroscopic signatures of C II λ6580 are detected and investigate the presence of C II λ6580 in the optical spectra of 19 SNe Ia using the parameterized spectrum synthesis code, SYNOW. Most of the objects in our sample that exhibit C II λ6580 absorption features are of the low-velocity gradient subtype. Our study indicates that the morphology of carbon-rich regions is consistent with either a spherical distribution or a hemispheric asymmetry, supporting the recent idea that SN Ia diversity may be a result of off-center ignition coupled with observer line-of-sight effects.

  19. Determination of ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb in NORM products from oil and gas exploration: problems in activity underestimation due to the presence of metals and self-absorption of photons.

    PubMed

    Landsberger, S; Brabec, C; Canion, B; Hashem, J; Lu, C; Millsap, D; George, G

    2013-11-01

    Typical calibration of solid environmental samples for the determination of (226)Ra, (228)Ra and (210)Pb entails the use of standard reference materials which have a very similar matrix. However, TENORM samples from the oil and gas exploration contain unusually high amounts of calcium, strontium and barium which can severely attenuate the photons of (210)Pb and (226)Ra with their characteristic 46.1 keV and 186.2 keV gamma-rays, respectively and to some extent (228)Ra with the characteristic gamma-rays of 911.2 keV and 969.0 keV. We used neutron activation analysis to evaluate the content of TENORM for calcium, barium and strontium and then used a software program SELABS to determine the self-absorption. Our results confirm that even in Petrie containers with small dimensions the (210)Pb can be underestimated by almost by a factor of four while (226)Ra can be underestimated by 5%. The (228)Ra activities are virtually unaffected due to the higher energy gamma-rays. However, the implications for TENORM studies that employ large Marinelli containers having sample sizes between 0.25 and 1.0 L may be severely compromised by the presence of high Z elements in elevated concentrations. The usual spectral interferences on (226)Ra, (228)Ra and (210)Pb coming from other radionuclides in the (234)U, (235)U and (238)U decay chains are virtually nonexistent due the very high activity levels of (226)Ra, (228)Ra and (210)Pb in the tens of thousands of Bq/kg. PMID:23514714

  20. Optical absorption components of light-modulated absorption spectrum of CdS

    NASA Technical Reports Server (NTRS)

    Conway, E. J.; Long, E. R.

    1975-01-01

    The amplitude and decay coefficient of light-induced modulation of absorption (LIMA) was measured as a function of wavelength from 535 to 850 nm for single-crystal CdS. The decay coefficient exhibited a discontinuous resonance at 710 nm which was due to the overlap and cancellation of two opposing absorption changes. A method was developed to separate these opposing absorption changes using the measured decay coefficients. The discrete-level-to-band energy for one absorption change was found to be 1.64 eV. An improved model was developed which contains two associated levels in the band gap separated by 0.32 eV.

  1. Circumstellar material in type Ia supernovae via sodium absorption features.

    PubMed

    Sternberg, A; Gal-Yam, A; Simon, J D; Leonard, D C; Quimby, R M; Phillips, M M; Morrell, N; Thompson, I B; Ivans, I; Marshall, J L; Filippenko, A V; Marcy, G W; Bloom, J S; Patat, F; Foley, R J; Yong, D; Penprase, B E; Beeler, D J; Allende Prieto, C; Stringfellow, G S

    2011-08-12

    Type Ia supernovae are key tools for measuring distances on a cosmic scale. They are generally thought to be the thermonuclear explosion of an accreting white dwarf in a close binary system. The nature of the mass donor is still uncertain. In the single-degenerate model it is a main-sequence star or an evolved star, whereas in the double-degenerate model it is another white dwarf. We show that the velocity structure of absorbing material along the line of sight to 35 type Ia supernovae tends to be blueshifted. These structures are likely signatures of gas outflows from the supernova progenitor systems. Thus, many type Ia supernovae in nearby spiral galaxies may originate in single-degenerate systems. PMID:21836010

  2. Formaldehyde absorption toward W51

    NASA Technical Reports Server (NTRS)

    Kogut, A.; Smoot, G. F.; Bennett, C. L.; Petuchowski, S. J.

    1989-01-01

    Formaldehyde (H2CO) absorption toward the H II region complex W51A (G49.5 - 0.4) in the 6 cm and 2 cm wavelength rotational transitions has been measured with angular resolution of about 0.15 pc. The continuum H II region shows a large, previously undetected shell structure 5.5 pc along the major axis. The absorption, converted to optical depth, shows a higher degree of clumping throughout the map than previous maps at lower resolution; in particular, two narrow regions of enhanced opacity are observed. The absorption in the velocity range 64-67 km/s LSR extends over most of the region, with an observed velocity gradient of 5.2 km/s pc. The opacity structure largely parallels the velocity structure, with a ridge of enhanced opacity to the north of the highest velocity feature. The S/N of the maps allows accurate modeling of the spectral profiles. Nine distinct clumps in the foreground clouds have been identified and parametrized, and column densities for the 1(11) and 2(12) rotational levels of orthoformaldehyde have been derived.

  3. JCE Feature Columns

    NASA Astrophysics Data System (ADS)

    Holmes, Jon L.

    1999-05-01

    The Features area of JCE Online is now readily accessible through a single click from our home page. In the Features area each column is linked to its own home page. These column home pages also have links to them from the online Journal Table of Contents pages or from any article published as part of that feature column. Using these links you can easily find abstracts of additional articles that are related by topic. Of course, JCE Online+ subscribers are then just one click away from the entire article. Finding related articles is easy because each feature column "site" contains links to the online abstracts of all the articles that have appeared in the column. In addition, you can find the mission statement for the column and the email link to the column editor that I mentioned above. At the discretion of its editor, a feature column site may contain additional resources. As an example, the Chemical Information Instructor column edited by Arleen Somerville will have a periodically updated bibliography of resources for teaching and using chemical information. Due to the increase in the number of these resources available on the WWW, it only makes sense to publish this information online so that you can get to these resources with a simple click of the mouse. We expect that there will soon be additional information and resources at several other feature column sites. Following in the footsteps of the Chemical Information Instructor, up-to-date bibliographies and links to related online resources can be made available. We hope to extend the online component of our feature columns with moderated online discussion forums. If you have a suggestion for an online resource you would like to see included, let the feature editor or JCE Online (jceonline@chem.wisc.edu) know about it. JCE Internet Features JCE Internet also has several feature columns: Chemical Education Resource Shelf, Conceptual Questions and Challenge Problems, Equipment Buyers Guide, Hal's Picks, Mathcad

  4. Atmospheric Solar Heating in Minor Absorption Bands

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah

    1998-01-01

    Solar radiation is the primary source of energy driving atmospheric and oceanic circulations. Concerned with the huge computing time required for computing radiative transfer in weather and climate models, solar heating in minor absorption bands has often been neglected. The individual contributions of these minor bands to the atmospheric heating is small, but collectively they are not negligible. The solar heating in minor bands includes the absorption due to water vapor in the photosynthetically active radiation (PAR) spectral region from 14284/cm to 25000/cm, the ozone absorption and Rayleigh scattering in the near infrared, as well as the O2 and CO2 absorption in a number of weak bands. Detailed high spectral- and angular-resolution calculations show that the total effect of these minor absorption is to enhance the atmospheric solar heating by approximately 10%. Depending upon the strength of the absorption and the overlapping among gaseous absorption, different approaches are applied to parameterize these minor absorption. The parameterizations are accurate and require little extra time for computing radiative fluxes. They have been efficiently implemented in the various atmospheric models at NASA/Goddard Space Flight Center, including cloud ensemble, mesoscale, and climate models.

  5. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  6. Solar absorption surface panel

    DOEpatents

    Santala, Teuvo J.

    1978-01-01

    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  7. Petawatt laser absorption bounded

    PubMed Central

    Levy, Matthew C.; Wilks, Scott C.; Tabak, Max; Libby, Stephen B.; Baring, Matthew G.

    2014-01-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials. PMID:24938656

  8. Petawatt laser absorption bounded

    NASA Astrophysics Data System (ADS)

    Levy, Matthew C.; Wilks, Scott C.; Tabak, Max; Libby, Stephen B.; Baring, Matthew G.

    2014-06-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials.

  9. Percutaneous absorption of drugs.

    PubMed

    Wester, R C; Maibach, H I

    1992-10-01

    The skin is an evolutionary masterpiece of living tissue which is the final control unit for determining the local and systemic availability of any drug which must pass into and through it. In vivo in humans, many factors will affect the absorption of drugs. These include individual biological variation and may be influenced by race. The skin site of the body will also influence percutaneous absorption. Generally, those body parts exposed to the open environment (and to cosmetics, drugs and hazardous toxic substances) are most affected. Treating patients may involve single daily drug treatment or multiple daily administration. Finally, the body will be washed (normal daily process or when there is concern about skin decontamination) and this will influence percutaneous absorption. The vehicle of a drug will affect release of drug to skin. On skin, the interrelationships of this form of administration involve drug concentration, surface area exposed, frequency and time of exposure. These interrelationships determine percutaneous absorption. Accounting for all the drug administered is desirable in controlled studies. The bioavailability of the drug then is assessed in relationship to its efficacy and toxicity in drug development. There are methods, both quantitative and qualitative, in vitro and in vivo, for studying percutaneous absorption of drugs. Animal models are substituted for humans to determine percutaneous absorption. Each of these methods thus becomes a factor in determining percutaneous absorption because they predict absorption in humans. The relevance of these predictions to humans in vivo is of intense research interest. The most relevant determination of percutaneous absorption of a drug in humans is when the drug in its approved formulation is applied in vivo to humans in the intended clinical situation. Deviation from this scenario involves the introduction of variables which may alter percutaneous absorption. PMID:1296607

  10. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  11. Why Replacing Different Oxygens of Thymine with Sulfur Causes Distinct Absorption and Intersystem Crossing.

    PubMed

    Bai, Shuming; Barbatti, Mario

    2016-08-18

    Recent experiments replacing oxygen atoms by sulfur in thymine have revealed that absorption and intersystem crossing properties of these derivatives are strongly dependent on the position and number of the substitutions, affecting their potential performance for photodynamical therapy. Using multireference quantum chemical methods (CASPT2 and DFT/MRCI), we calculated absorption spectra and spin-orbit coupling matrix elements for thymine (Thy), 2-thiothymine (2tThy), 4-thiothymine (4tThy), and 2,4-dithiothymine (2,4dtThy), to investigate this relation between structure and photophysics. The simulations showed that a simple 4-electrons/4-orbital minimum model can explain the main experimentally observed spectral features. Moreover, the computational estimate of intersystem crossing lifetimes in this sequence of molecules revealed that the experimental value attributed to thymine in water might be underestimated by a factor 20, most probably due to an overlap of singlet/triplet absorption signals in the transient absorption spectrum. The difference between the absorptivity of 2tThy and 2tThd was also investigated, but no conclusive explanation could be found. PMID:27454198

  12. Seismic signatures of carbonate caves affected by near-surface absorptions

    NASA Astrophysics Data System (ADS)

    Rao, Ying; Wang, Yanghua

    2015-12-01

    The near-surface absorption within a low-velocity zone generally has an exponential attenuation effect on seismic waves. But how does this absorption affect seismic signatures of karstic caves in deep carbonate reservoirs? Seismic simulation and analysis reveals that, although this near-surface absorption attenuates the wave energy of a continuous reflection, it does not alter the basic kinematic shape of bead-string reflections, a special seismic characteristic associated with carbonate caves in the Tarim Basin, China. Therefore, the bead-strings in seismic profiles can be utilized, with a great certainty, for interpreting the existence of caves within the deep carbonate reservoirs and for evaluating their pore spaces. Nevertheless, the difference between the central frequency and the peak frequency is increased along with the increment in the absorption. While the wave energy of bead-string reflections remains strong, due to the interference of seismic multiples generated by big impedance contrast between the infill materials of a cave and the surrounding carbonate rocks, the central frequency is shifted linearly with respect to the near-surface absorption. These two features can be exploited simultaneously, for a stable attenuation analysis of field seismic data.

  13. A search for formic acid in the upper troposphere - A tentative identification of the 1105-per cm nu-6 band Q branch in high-resolution balloon-borne solar absorption spectra

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.

    1984-01-01

    Infrared solar absorption spectra recorded at 0.02-per cm resolution during a balloon flight from Alamogordo, NM (33 deg N), on March 23, 1981, have been analyzed for the possible presence of absorption by formic acid (HCOOH). An absorption feature at 1105 per cm has been tentatively identified in upper tropospheric spectra as due to the nu-6 band Q branch. A preliminary analysis indicates a concentration of about 0.6 ppbv and 0.4 ppbv near 8 and 10 km, respectively.

  14. A Search for Formic Acid in the Upper Troposphere: A Tentative Identification of the 1105-cm(exp -1) nu(sub 6) Band Q Branch in High-Resolution Balloon-Borne Solar Absorption Spectra

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.

    1984-01-01

    Infrared solar absorption spectra recorded at 0.02/cm resolution during a balloon flight from Alamogordo, N.M. (33 deg N), on March 23, 1981, have been analyzed for the possible presence of absorption by formic acid (HCOOH). An absorption feature at 1105/ cm has been tentatively identified in upper tropospheric spectra as due to the nu(sub 6) band Q branch. A preliminary analysis indicates a concentration of approx. = 0.6 ppbv and approx. = 0.4 ppbv near 8 and 10 km, respectively.

  15. Depressive disorder due to craniopharyngioma.

    PubMed Central

    Spence, S A; Taylor, D G; Hirsch, S R

    1995-01-01

    Secondary causes of depression are legion, and must always be considered in patients presenting with features atypical of primary idiopathic depressive disorder. The case described is that of a middle-aged woman presenting initially with a major depressive disorder who was subsequently found to have a craniopharyngioma, leading to a revised diagnosis of mood disorder due to the tumour. Some features of the presentation might have led to earlier diagnosis had their localizing significance been recognized. Diencephalic lesions should always be considered in patients presenting with the hypersomnic-hyperphagic variant of depressive disorder. Images Figure 1 PMID:8544149

  16. The Hubble Space Telescope quasar absorption line key project. II - Data calibration and absorption-line selection

    NASA Technical Reports Server (NTRS)

    Schneider, Donald P.; Hartig, George F.; Jannuzi, Buell T.; Kirhakos, Sofia; Saxe, David H.; Weymann, Ray J.; Bahcall, John N.; Bergeron, Jacqueline; Boksenberg, Alec; Sargent, W. L. W.

    1993-01-01

    We present the observational and data processing aspects of the Hubble Space Telescope Quasar Absorption Line Key Project. Topics discussed include the observational technique, calibration of the data, software that simulates the data, the automated procedure used to identify and characterize the absorption features, and the determination of the sensitivity limits of the survey.

  17. Absorption chillers: Technology for the future

    SciTech Connect

    Garland, P.W.; Garland, R.W.

    1997-12-31

    In an era of heightened awareness of energy efficiency and the associated environmental impacts, many industries worldwide are exploring ``environmentally friendly`` technologies that provide equivalent or improved performance while reducing or eliminating harmful side-effects. The refrigeration and air-conditioning industry, due to its reliance on CFCs and HCFCs, has invested in research in alternatives to the industry standard vapor compression machines. One alternative technology with great promise is chemical absorption. Absorption chillers offer comparable refrigeration output with reduced SO{sub 2}, CO{sub 2}, and NO{sub x} emissions. Absorption chillers do not use CFCs or HCFCs, refrigerants that contribute to ozone depletion and global warming. Additionally, gas-fired absorption chillers can save significant amounts in energy costs when used in combination with a vapor compression chiller in a hybrid system. The hybrid system can take advantage of the comparatively low price of natural gas (per unit ton) and rely on the high performance of vapor compression when electricity prices are lower. The purpose of this article is to provide an introduction for those new to absorption technology as well as a discussion of selected high efficiency cycles, a discussion on the technology of coupling absorption with vapor compression systems to form a hybrid system, and the environmental impacts of absorption.

  18. Compounds affecting cholesterol absorption

    NASA Technical Reports Server (NTRS)

    Hua, Duy H. (Inventor); Koo, Sung I. (Inventor); Noh, Sang K. (Inventor)

    2004-01-01

    A class of novel compounds is described for use in affecting lymphatic absorption of cholesterol. Compounds of particular interest are defined by Formula I: ##STR1## or a pharmaceutically acceptable salt thereof.

  19. Absorption heat pump system

    DOEpatents

    Grossman, Gershon

    1984-01-01

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  20. Absorption heat pump system

    DOEpatents

    Grossman, G.

    1982-06-16

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  1. Dipeptide absorption in man

    PubMed Central

    Hellier, M. D.; Holdsworth, C. D.; McColl, I.; Perrett, D.

    1972-01-01

    A quantitative perfusion method has been used to study intestinal absorption of two dipeptides—glycyl-glycine and glycyl-l-alanine—in normal subjects. In each case, the constituent amino acids were absorbed faster when presented as dipeptides than as free amino acids, suggesting intact dipeptide transport. During absorption constituent amino acids were measured within the lumen and it is suggested that these represent amino acids which have diffused back to the lumen after absorption as dipeptide. Portal blood analyses during absorption of a third dipeptide, glycyl-l-lysine, have shown that this dipeptide, known to be transported intact from the intestinal lumen, is hydrolysed to its constitutent amino acids before it reaches portal venous blood. PMID:4652039

  2. Optical absorption measurement system

    DOEpatents

    Draggoo, Vaughn G.; Morton, Richard G.; Sawicki, Richard H.; Bissinger, Horst D.

    1989-01-01

    The system of the present invention contemplates a non-intrusive method for measuring the temperature rise of optical elements under high laser power optical loading to determine the absorption coefficient. The method comprises irradiating the optical element with a high average power laser beam, viewing the optical element with an infrared camera to determine the temperature across the optical element and calculating the absorption of the optical element from the temperature.

  3. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2004-08-31

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  4. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2003-10-14

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  5. Electromagnetically induced absorption via incoherent collisions

    SciTech Connect

    Yang Xihua; Sheng Jiteng; Xiao Min

    2011-10-15

    We conduct theoretical studies on electromagnetically induced absorption via incoherent collisions in an inhomogeneously broadened ladder-type three-level system with the density-matrix approach. The effects of the collision-induced coherence decay rates as well as the probe laser field intensity on the probe field absorption are examined. It is shown that with the increase of the collisional decay rates in a moderate range, a narrow dip due to electromagnetically induced transparency superimposed on the Doppler-broadened absorption background can be turned into a narrow peak under the conditions that the probe field intensity is not very weak as compared to the pump field, which results from the enhancement of constructive interference and suppression of destructive interference between one-photon and multiphoton transition pathways. The physical origin of the collision-assisted electromagnetically induced absorption is analyzed with a power-series solution of the density-matrix equations.

  6. Multiphoton absorption in amyloid protein fibres

    NASA Astrophysics Data System (ADS)

    Hanczyc, Piotr; Samoc, Marek; Norden, Bengt

    2013-12-01

    Fibrillization of peptides leads to the formation of amyloid fibres, which, when in large aggregates, are responsible for diseases such as Alzheimer's and Parkinson's. Here, we show that amyloids have strong nonlinear optical absorption, which is not present in native non-fibrillized protein. Z-scan and pump-probe experiments indicate that insulin and lysozyme β-amyloids, as well as α-synuclein fibres, exhibit either two-photon, three-photon or higher multiphoton absorption processes, depending on the wavelength of light. We propose that the enhanced multiphoton absorption is due to a cooperative mechanism involving through-space dipolar coupling between excited states of aromatic amino acids densely packed in the fibrous structures. This finding will provide the opportunity to develop nonlinear optical techniques to detect and study amyloid structures and also suggests that new protein-based materials with sizable multiphoton absorption could be designed for specific applications in nanotechnology, photonics and optoelectronics.

  7. Estimation of molar absorptivities and pigment sizes for eumelanin and pheomelanin using femtosecond transient absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Piletic, Ivan R.; Matthews, Thomas E.; Warren, Warren S.

    2009-11-01

    Fundamental optical and structural properties of melanins are not well understood due to their poor solubility characteristics and the chemical disorder present during biomolecular synthesis. We apply nonlinear transient absorption spectroscopy to quantify molar absorptivities for eumelanin and pheomelanin and thereby get an estimate for their average pigment sizes. We determine that pheomelanin exhibits a larger molar absorptivity at near IR wavelengths (750nm), which may be extended to shorter wavelengths. Using the molar absorptivities, we estimate that melanin pigments contain ˜46 and 28 monomer units for eumelanin and pheomelanin, respectively. This is considerably larger than the oligomeric species that have been recently proposed to account for the absorption spectrum of eumelanin and illustrates that larger pigments comprise a significant fraction of the pigment distribution.

  8. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  9. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, R.C.; Biermann, W.J.

    1989-05-09

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit. 1 fig.

  10. Multiplexed absorption tomography with calibration-free wavelength modulation spectroscopy

    SciTech Connect

    Cai, Weiwei; Kaminski, Clemens F.

    2014-04-14

    We propose a multiplexed absorption tomography technique, which uses calibration-free wavelength modulation spectroscopy with tunable semiconductor lasers for the simultaneous imaging of temperature and species concentration in harsh combustion environments. Compared with the commonly used direct absorption spectroscopy (DAS) counterpart, the present variant enjoys better signal-to-noise ratios and requires no baseline fitting, a particularly desirable feature for high-pressure applications, where adjacent absorption features overlap and interfere severely. We present proof-of-concept numerical demonstrations of the technique using realistic phantom models of harsh combustion environments and prove that the proposed techniques outperform currently available tomography techniques based on DAS.

  11. Line shape studies in CW dye laser intracavity absorption

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Brink, G. O.; Spence, S.; Lakkaraju, H. S.

    1980-01-01

    The line shape of the signals observed by intracavity absorption in an atomic beam of barium is studied as a function of absorber density. Complex structure is observed consisting of both absorption and enhancement features. Comparison is made with models of intracavity absorption, and it is concluded that the rate equation model in its present form does not explain the structure. On the other hand the super-regen model does seem able to partially account for the observed structure. The complexity of the line shape will directly affect those workers who are using intracavity absorption as a spectroscopic technique.

  12. Multi-wavelength differential absorption measurements of chemical species

    NASA Astrophysics Data System (ADS)

    Brown, David M.

    algorithms to select filters for use with a MWIR (midwave infrared) imager for detection of plumes of methane, propane, gasoline vapor, and diesel vapor. These simulations were prepared for system designs operating on a down-looking airborne platform. A data analysis algorithm for use with a hydrocarbon imaging system extracts regions of interest from the field-of-view for further analysis. An error analysis is presented for a scanning DAS (Differential Absorption Spectroscopy) lidar system operating from an airborne platform that uses signals scattered from topographical targets. The analysis is built into a simulation program for testing real-time data processing approaches, and to gauge the effects on measurements of path column concentration due to ground reflectivity variations. An example simulation provides a description of the data expected for methane. Several accomplishments of this research include: (1) A new lidar technique for detection and measurement of concentrations of atmospheric species is demonstrated that uses a low-power supercontinuum source. (2) A new multi-wavelength algorithm, which demonstrates excellent performance, is applied to processing spectroscopic data collected by a longpath supercontinuum laser absorption instrument. (3) A simulation program for topographical scattering of a scanning DAS system is developed, and it is validated with aircraft data from the ITT Industries ANGEL (Airborne Natural Gas Emission Lidar) 3-lambda lidar system. (4) An error analysis procedure for DAS is developed, and is applied to measurements and simulations for an airborne platform. (5) A method for filter selection is developed and tested for use with an infrared imager that optimizes the detection for various hydrocarbons that absorb in the midwave infrared. (6) The development of a Fourier analysis algorithm is described that allows a user to rapidly separate hydrocarbon plumes from the background features in the field of view of an imaging system.

  13. Design and synthesis of liquid crystals with controlled absorption properties in the midwave infrared region

    NASA Astrophysics Data System (ADS)

    Tripathi, Suvagata

    The infrared region of electromagnetic radiation is attractive for communication applications as the scattering is lower compared to that in the visible spectrum. Infrared lasers are widely used in bar-code scanners, laser rangefinders and topology mapping applications. Typically, the direction of a laser beam is altered by mechanically moving a mirror or a lens. But this process can impose severe limitations on critical performance parameters (longevity, precision, response time etc.) of the device. Thus, electro-optic control of the direction of the beam is highly desired. Commercial liquid crystals (LCs) are less than ideal for this purpose because they almost invariably have several absorption bands in the infrared region. For example, several absorption bands exist in the mid-infrared region (3-5 mum) due to common structure features found in LCs such as CH, CH 2, CH3 and CN. In the off-resonance regions, the baseline absorption coefficient can take very high value (up to alpha ~10/cm). This absorption loss becomes especially significant if the optical path is long. As the molecular vibration frequency (o) depends upon the spring constant (kappa) and the effective mass (m) of a diatomic group by the equation = √(kappa/m), replacement of hydrogen atoms in a molecule with heavier atoms can shift the absorptions to the far infrared region, thus making the midwave infrared region more transparent. Another strategy has been to develop high birefringence LCs so that lower liquid crystal cell gap can be used, thus minimizing the absorption loss due to the LC layer. But most of these materials have problems with UV stability. In the scope of this thesis, several strategies are investigated to mitigate the absorption loss in the midwave infrared region. The ultimate goal of this thesis is to develop LCs that will have both high birefringence and low absorption properties in the midwave-infrared region. Another goal of the thesis is to develop materials for

  14. Petawatt laser absorption bounded

    NASA Astrophysics Data System (ADS)

    Levy, Matthew; Wilks, Scott; Tabak, Max; Libby, Stephen; Baring, Matthew

    2014-10-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top relativistic particle accelerators, ultrafast charged particle imaging systems and fast ignition inertial confinement fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. In this presentation, using a relativistic Rankine-Hugoniot-like analysis, we show how to derive the theoretical maximum and minimum of f. These boundaries constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. Close agreement is shown with several dozens of published experimental data points and simulation results, helping to confirm the theory. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials.

  15. Percutaneous absorption of Octopirox.

    PubMed

    Black, J G; Kamat, V B

    1988-01-01

    containing 1% Octopirox is 29,400, so that the possibility of systemic effects due to absorption through the skin is remote. PMID:3345970

  16. Nebular Hydrogen Absorption in the Ejecta of Eta Carinae

    NASA Technical Reports Server (NTRS)

    Gull, Theodore R.; Ishibashi, K.; Davidson, K.; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    Space Telescope Imaging Spectrograph (STIS) observations of Eta Carinae and immediate ejecta reveal narrow Balmer absorption lines in addition to the nebular-scattered broad P-Cygni absorptions. The narrow absorption correlates with apparent disk structure that separates the two Homunculus lobes. We trace these features about half way up the Northern lobe until the scattered stellar Balmer line doppler-shifts redward beyond the nebular absorption feature. Three-dimensional data cubes, made by mapping the Homunculus at Balmer alpha and Balmer beta with the 52 x 0.1 arcsecond aperture and about 5000 spectral resolving power, demonstrate that the absorption feature changes slowly in velocity with nebular position. We have monitored the stellar Balmer alpha line profile of the central source over the past four years. The equivalent width of the nebular absorption feature changes considerably between observations. The changes do not correlate with measured brightness of Eta Carinae. Likely clumps of neutral hydrogen with a scale size comparable to the stellar disk diameter are passing through the intervening light path on the timescales less than several months. The excitation mechanism involves Lyman alpha radiation (possibly the Lyman series plus Lyman continuum) and collisions leading to populating the 2S metastable state. Before the electron can jump to the ground state by two photon emission (lifetime about 1/8 second), a stellar Balmer photon is absorbed and the electron shifts to an NP level. We see the absorption feature in higher Balmer lines, and but not in Paschen lines. Indeed we see narrow nebular Paschen emission lines. At present, we do not completely understand the details of the absorption. Better understanding should lead to improved insight of the unique conditions around Eta Carinae that leads to these absorptions.

  17. Infrared differential absorption for atmospheric pollutant detection

    NASA Technical Reports Server (NTRS)

    Byer, R. L.

    1974-01-01

    Progress made in the generation of tunable infrared radiation and its application to remote pollutant detection by the differential absorption method are summarized. It is recognized that future remote pollutant measurements depended critically on the availability of high energy tunable transmitters. Futhermore, due to eye safety requirements, the transmitted frequency must lie in the 1.4 micron to 13 micron infrared spectral range.

  18. Intestinal Water Absorption Varies with Expected Dietary Water Load among Bats but Does Not Drive Paracellular Nutrient Absorption.

    PubMed

    Price, Edwin R; Brun, Antonio; Gontero-Fourcade, Manuel; Fernández-Marinone, Guido; Cruz-Neto, Ariovaldo P; Karasov, William H; Caviedes-Vidal, Enrique

    2015-01-01

    Rapid absorption and elimination of dietary water should be particularly important to flying species and were predicted to vary with the water content of the natural diet. Additionally, high water absorption capacity was predicted to be associated with high paracellular nutrient absorption due to solvent drag. We compared the water absorption rates of sanguivorous, nectarivorous, frugivorous, and insectivorous bats in intestinal luminal perfusions. High water absorption rates were associated with high expected dietary water load but were not highly correlated with previously measured rates of (paracellular) arabinose clearance. In conjunction with these tests, we measured water absorption and the paracellular absorption of nutrients in the intestine and stomach of vampire bats using luminal perfusions to test the hypothesis that the unique elongated vampire stomach is a critical site of water absorption. Vampire bats' gastric water absorption was high compared to mice but not compared to their intestines. We therefore conclude that (1) dietary water content has influenced the evolution of intestinal water absorption capacity in bats, (2) solvent drag is not the only driver of paracellular nutrient absorption, and (3) the vampire stomach is a capable but not critical location for water absorption. PMID:26658415

  19. Percutaneous absorption from soil.

    PubMed

    Andersen, Rosa Marie; Coman, Garrett; Blickenstaff, Nicholas R; Maibach, Howard I

    2014-01-01

    Abstract Some natural sites, as a result of contaminants emitted into the air and subsequently deposited in soil or accidental industrial release, have high levels of organic and non-organic chemicals in soil. In occupational and recreation settings, these could be potential sources of percutaneous exposure to humans. When investigating percutaneous absorption from soil - in vitro or vivo - soil load, particle size, layering, soil "age" time, along with the methods of performing the experiment and analyzing the results must be taken into consideration. Skin absorption from soil is generally reduced compared with uptake from water/acetone. However, the absorption of some compounds, e.g., pentachlorophenol, chlorodane and PCB 1254, are similar. Lipophilic compounds like dichlorodiphenyltrichloroethane, benzo[A]pyrene, and metals have the tendency to form reservoirs in skin. Thus, one should take caution in interpreting results directly from in vitro studies for risk assessment; in vivo validations are often required for the most relevant risk assessment. PMID:25205703

  20. Development of Updated ABsorption SIMulation Software (ABSIM)

    SciTech Connect

    Yang, Zhiyao; Tang, Xin; Qu, Ming; Abdelaziz, Omar; Gluesenkamp, Kyle R

    2014-01-01

    ABsorption SIMulation, ABSIM, was developed for the simulation of absorption systems by The Oak Ridge National Laboratory during 1980s and 1990s. ABSIM provides a platform for users to investigate various cycle configurations and working fluids, to calculate their operating parameters, to predict their performance, and to compare them with each other on a uniform basis. ABSIM is indeed a very useful and accurate tool for researchers to investigate various absorption systems. However, it has not been well maintained: it is incompatible with recent operating systems; the interface needs improved user-friendliness, and the system needs better parameter setting and debugging tools to help achieve convergence. Therefore, it is highly needed to update and improve ABSIM. The paper presents recent efforts to improve ABSIM s compatibility with current operating systems, user interface, and analysis capabilities. The paper details the features and functions of the newly updated ABSIM software. The new ABSIM still uses the previously validated calculation engine of the old ABSIM. The new graphic user interfaces (GUI) were developed in Qt, which is an open source license GUI software based on C++. XML was used as the database for data storage in the new ABSIM. The new ABSIM has been designed to be easily learned and used. It has enhanced editing and construction functions, plus enhanced analysis features including parametric tables, plotting, property plots, and master panels for debugging. A single effect water/LiBr absorption system is used as a case study in this paper to illustrate the features, capabilities, and functions of the new ABSIM. This case study was actually an example system available in the old ABSIM. The new version of ABSIM will be continuously developed to include additional subroutines for the components in liquid desiccant systems. The new ABSIM will be available to public for free. The ultimate goal of the new ABSIM is to allow it to become a simulation

  1. Electrochromic poly(acetylene)s with switchable visible/near-IR absorption characteristics.

    PubMed

    Pauly, Anja C; Varnado, C Daniel; Bielawski, Christopher W; Theato, Patrick

    2014-01-01

    Ferrocene is incorporated into a poly(acetylene) derivative via the postpolymerization amidation of a polymer precursor bearing pentafluorophenyl ester-leaving groups with aminoferrocene. While the neutral polymer exhibits a strong absorbance at 553 nm due to its conjugated backbone, oxidation of the ferrocene moieties with silver tetrafluoroborate causes the material to absorb in the near-IR (λ max ≈ 1215 nm). Subsequent reduction of the oxidized polymer with decamethylferrocene restores the initial absorbance profile, demonstrating that the material features switchable visible/near-IR absorption characteristics. PMID:23996218

  2. Epignathus with Fetiform Features

    PubMed Central

    Kumar, Sunil Y; Shrikrishna, U; Shetty, Jayaprakash; Sitaram, Aishwarya

    2011-01-01

    Epignathus is an extremely rare oropharyngeal teratoma that commonly arises from the palate, leading to a high mortality (80–100%) due to airway obstruction in the neonatal period. We present a case of epignathus immature teratoma with fetiform features, originating from basisphenoid in a 28-week preterm male baby, who succumbed to death immediately after birth. Since epignathus is a life-threatening condition at the time of delivery, a prenatal diagnosis is essential to coordinate the treatment and appropriate management by securing the airway, either by endotracheal intubation or tracheostomy followed by complete resection of the tumor. PMID:21701667

  3. Multiplasmon Absorption in Graphene

    NASA Astrophysics Data System (ADS)

    Jablan, Marinko; Chang, Darrick E.

    2015-06-01

    We show that graphene possesses a strong nonlinear optical response in the form of multiplasmon absorption, with exciting implications in classical and quantum nonlinear optics. Specifically, we predict that graphene nanoribbons can be used as saturable absorbers with low saturation intensity in the far-infrared and terahertz spectrum. Moreover, we predict that two-plasmon absorption and extreme localization of plasmon fields in graphene nanodisks can lead to a plasmon blockade effect, in which a single quantized plasmon strongly suppresses the possibility of exciting a second plasmon.

  4. Chaotic Systems with Absorption

    NASA Astrophysics Data System (ADS)

    Altmann, Eduardo G.; Portela, Jefferson S. E.; Tél, Tamás

    2013-10-01

    Motivated by applications in optics and acoustics we develop a dynamical-system approach to describe absorption in chaotic systems. We introduce an operator formalism from which we obtain (i) a general formula for the escape rate κ in terms of the natural conditionally invariant measure of the system, (ii) an increased multifractality when compared to the spectrum of dimensions Dq obtained without taking absorption and return times into account, and (iii) a generalization of the Kantz-Grassberger formula that expresses D1 in terms of κ, the positive Lyapunov exponent, the average return time, and a new quantity, the reflection rate. Simulations in the cardioid billiard confirm these results.

  5. Absorption heat pump system

    DOEpatents

    Grossman, Gershon; Perez-Blanco, Horacio

    1984-01-01

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  6. Laser Absorption by Over-Critical Plasmas

    NASA Astrophysics Data System (ADS)

    May, J.; Tonge, J.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.; Mori, W. B.

    2015-11-01

    Absorption of high intensity laser light by matter has important applications to emerging sciences and technology, such as Fast Ignition ICF and ion acceleration. As such, understanding the underlying mechanisms of this absorption is key to developing these technologies. Critical features which distinguish the interaction of high intensity light - defined here as a laser field having a normalized vector potential greater than unity - are that the reaction of the material to the fields results in sharp high-density interfaces; and that the movement of the electrons is in general relativistic, both in a fluid and a thermal sense. The results of these features are that the absorption mechanisms are qualitatively distinct from those at lower intensities. We will review previous work, by our group and others, on the absorption mechanisms, and highlight current research. We will show that the standing wave structure of the reflected laser light is key to particle dynamics for normally incident lasers. The authors acknowledge the support of the Department of Energy under contract DE-NA 0001833 and the National Science Foundation under contract ACI 1339893.

  7. Nebular UV Absorption Lines in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet

    We propose to continue our Cycle 1 program of studying the Lyman and Werner bands of H_2, seen in absorption against the UV continua of planetary nebula central stars, which arise within neutral-molecular envelopes surrounding the ionized gas. These are the pump lines for a fluorescent cascade of near-infrared emission lines which are observed in many planetary nebulae. By observing the UV lines we can probe the chemical and thermal structure of the envelopes, as well as measure molecular column densities and clarify the excitation processes for the infrared lines. In Cycle 1 we were granted time for three targets, one of which was successfully observed shortly before submission of this proposal. Although the data were not yet available for examination, similar target observed by the project team revealed a rich set of H_2 circumstellar absorption features, demonstrating the feasibility of our program. FUSE spectra also include absorption features from atomic species such as O I and C II, which give rise to important far-infrared fine-structure cooling lines that likewise have been observed from planetary nebulae. In Cycle 2, we add as a secondary goal a search for nebular components of the O VI 032, 1038 AA absorption lines, which trace the presence of hot shocked gas, in nebulae with anomalously strong optical recombination lines of ions of oxygen and nitrogen. This will test a plausible hypothesis for the origin of this anomaly.

  8. Time-varying sodium absorption in the Type Ia supernova 2013gh

    NASA Astrophysics Data System (ADS)

    Ferretti, R.; Amanullah, R.; Goobar, A.; Johansson, J.; Vreeswijk, P. M.; Butler, R. P.; Cao, Y.; Cenko, S. B.; Doran, G.; Filippenko, A. V.; Freeland, E.; Hosseinzadeh, G.; Howell, D. A.; Lundqvist, P.; Mattila, S.; Nordin, J.; Nugent, P. E.; Petrushevska, T.; Valenti, S.; Vogt, S.; Wozniak, P.

    2016-07-01

    Context. Temporal variability of narrow absorption lines in high-resolution spectra of Type Ia supernovae (SNe Ia) is studied to search for circumstellar matter. Time series which resolve the profiles of absorption lines such as Na I D or Ca II H&K are expected to reveal variations due to photoionisation and subsequent recombination of the gases. The presence, composition, and geometry of circumstellar matter may hint at the elusive progenitor system of SNe Ia and could also affect the observed reddening law. Aims: To date, there are few known cases of time-varying Na I D absorption in SNe Ia, all of which occurred during relatively late phases of the supernova (SN) evolution. Photoionisation, however, is predicted to occur during the early phases of SNe Ia, when the supernovae peak in the ultraviolet. We attempt, therefore, to observe early-time absorption-line variations by obtaining high-resolution spectra of SNe before maximum light. Methods: We have obtained photometry and high-resolution spectroscopy of SNe Ia 2013gh and iPTF 13dge, to search for absorption-line variations. Furthermore, we study interstellar absorption features in relation to the observed photometric colours of the SNe. Results: Both SNe display deep Na I D and Ca II H&K absorption features. Furthermore, small but significant variations are detected in a feature of the Na I D profile of SN 2013gh. The variations are consistent with either geometric effects of rapidly moving or patchy gas clouds or photoionisation of Na I gas at R ≈ 1019 cm from the explosion. Conclusions: Our analysis indicates that it is necessary to focus on early phases to detect photoionisation effects of gases in the circumstellar medium of SNe Ia. Different absorbers such as Na I and Ca II can be used to probe for matter at different distances from the SNe. The nondetection of variations during early phases makes it possible to put limits on the abundance of the species at those distances. Full Tables 2 and 3 are only

  9. Single shot near edge x-ray absorption fine structure spectroscopy in the laboratory

    NASA Astrophysics Data System (ADS)

    Mantouvalou, I.; Witte, K.; Martyanov, W.; Jonas, A.; Grötzsch, D.; Streeck, C.; Löchel, H.; Rudolph, I.; Erko, A.; Stiel, H.; Kanngießer, B.

    2016-05-01

    With the help of adapted off-axis reflection zone plates, near edge X-ray absorption fine structure spectra at the C and N K-absorption edge have been recorded using a single 1.2 ns long soft X-ray pulse. The transmission experiments were performed with a laser-produced plasma source in the laboratory rendering time resolved measurements feasible independent on large scale facilities. A resolving power of E/ΔE ˜ 950 at the respective edges could be demonstrated. A comparison of single shot spectra with those collected with longer measuring time proves that all features of the used reference samples (silicon nitrate and polyimide) can be resolved in 1.2 ns. Hence, investigations of radiation sensitive biological specimen become possible due to the high efficiency of the optical elements enabling low dose experiments.

  10. Measurement and calculation of the sound absorption coefficient of pine wood charcoal

    NASA Astrophysics Data System (ADS)

    Suh, Jae Gap; Baik, Kyung min; Kim, Yong Tae; Jung, Sung Soo

    2013-10-01

    Although charcoal has been widely utilized for physical therapy and as a deodorant, water purifier, etc. due to its porous features, research on its role as a sound-absorbing material is rarely found. Thus, the sound absorption coefficients of pine wood charcoal were measured using an impedance tube and were compared with the theoretical predictions in the frequency range of 500˜ 5000 Hz. The theory developed in the current study only considers the lowest possible mode propagating along the air channels of the charcoal and shows good agreements with the measurements. As the frequency is increased, the sound absorption coefficients of pine wood charcoals also increase, but are lower than those of other commonly-used sound-absorbing materials.

  11. Zinc absorption in inflammatory bowel disease

    SciTech Connect

    Valberg, L.S.; Flanagan, P.R.; Kertesz, A.; Bondy, D.C.

    1986-07-01

    Zinc absorption was measured in 29 patients with inflammatory bowel disease and a wide spectrum of disease activity to determine its relationship to disease activity, general nutritional state, and zinc status. Patients with severe disease requiring either supplementary oral or parenteral nutrition were excluded. The mean 65ZnCl2 absorption, in the patients, determined using a 65Zn and 51Cr stool-counting test, 45 +/- 17% (SD), was significantly lower than the values, 54 +/- 16%, in 30 healthy controls, P less than 0.05. Low 65ZnCl2 absorption was related to undernutrition, but not to disease activity in the absence of undernutrition or to zinc status estimated by leukocyte zinc measurements. Mean plasma zinc or leukocyte zinc concentrations in patients did not differ significantly from controls, and only two patients with moderate disease had leukocyte zinc values below the 5th percentile of normal. In another group of nine patients with inflammatory bowel disease of mild-to-moderate severity and minimal nutritional impairment, 65Zn absorption from an extrinsically labeled turkey test meal was 31 +/- 10% compared to 33 +/- 7% in 17 healthy controls, P greater than 0.1. Thus, impairment in 65ZnCl2 absorption in the patients selected for this study was only evident in undernourished persons with moderate or severe disease activity, but biochemical evidence of zinc deficiency was uncommon, and clinical features of zinc depletion were not encountered.

  12. Two-Phonon Absorption

    ERIC Educational Resources Information Center

    Hamilton, M. W.

    2007-01-01

    A nonlinear aspect of the acousto-optic interaction that is analogous to multi-photon absorption is discussed. An experiment is described in which the second-order acousto-optically scattered intensity is measured and found to scale with the square of the acoustic intensity. This experiment using a commercially available acousto-optic modulator is…

  13. Total absorption Cherenkov spectrometers

    NASA Astrophysics Data System (ADS)

    Malinovski, E. I.

    2015-05-01

    A short review of 50 years of work done with Cherenkov detectors in laboratories at the Lebedev Physical Institute is presented. The report considers some issues concerning the use of Cherenkov total absorption counters based on lead glass and heavy crystals in accelerator experiments.

  14. Cholesterol Absorption and Metabolism.

    PubMed

    Howles, Philip N

    2016-01-01

    Inhibitors of cholesterol absorption have been sought for decades as a means to treat and prevent cardiovascular diseases (CVDs) associated with hypercholesterolemia. Ezetimibe is the one clear success story in this regard, and other compounds with similar efficacy continue to be sought. In the last decade, the laboratory mouse, with all its genetic power, has become the premier experimental model for discovering the mechanisms underlying cholesterol absorption and has become a critical tool for preclinical testing of potential pharmaceutical entities. This chapter briefly reviews the history of cholesterol absorption research and the various gene candidates that have come under consideration as drug targets. The most common and versatile method of measuring cholesterol absorption is described in detail along with important considerations when interpreting results, and an alternative method is also presented. In recent years, reverse cholesterol transport (RCT) has become an area of intense new interest for drug discovery since this process is now considered another key to reducing CVD risk. The ultimate measure of RCT is sterol excretion and a detailed description is given for measuring neutral and acidic fecal sterols and interpreting the results. PMID:27150091

  15. ZINC ABSORPTION BY INFANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Zinc is a vital mineral in human nutrition, and rare cases of overt zinc deficiency are well described in term and preterm infants. A variety of methods have been developed to assess zinc absorption, retention, and balance in humans, either using mass (metabolic) balance or stable isotope-based METH...

  16. Absorption driven focus shift

    NASA Astrophysics Data System (ADS)

    Harrop, N.; Wolf, S.; Maerten, O.; Dudek, K.; Ballach, S.; Kramer, R.

    2016-03-01

    Modern high brilliance near infrared lasers have seen a tremendous growth in applications throughout the world. Increased productivity has been achieved by higher laser power and increased brilliance of lasers. Positive impacts on the performance and costs of parts are opposed to threats on process stability and quality, namely shift of focus position over time. A high initial process quality will be reduced by contamination of optics, eventually leading to a focus shift or even destruction of the optics. Focus analysis at full power of multi-kilowatt high brilliance lasers is a very demanding task because of high power densities in the spot and the high power load on optical elements. With the newly developed high power projection optics, the High-Power Micro-Spot Monitor High Brilliance (HP-MSM-HB) is able to measure focus diameter as low as 20 μm at power levels up to 10 kW at very low internal focus shift. A main driving factor behind thermally induced focus shift is the absorption level of the optical element. A newly developed measuring system is designed to determine the relative absorption level in reference to a gold standard. Test results presented show a direct correlation between absorption levels and focus shift. The ability to determine the absorption level of optical elements as well as their performance at full processing power before they are put to use, enables a high level of quality assurance for optics manufacturers and processing head manufacturers alike.

  17. Fractal-like receiver geometries and features for increased light trapping and thermal efficiency

    NASA Astrophysics Data System (ADS)

    Ho, Clifford K.; Christian, Joshua M.; Yellowhair, Julius; Ortega, Jesus; Andraka, Charles

    2016-05-01

    Novel designs to increase light trapping and thermal efficiency of concentrating solar receivers at multiple length scales have been conceived and tested. The fractal-like geometries and features are introduced at both macro (meters) and meso (millimeters to centimeters) scales. Advantages include increased solar absorptance, reduced thermal emittance, and increased thermal efficiency. Radial and linear structures at the meso (tube shape and geometry) and macro (total receiver geometry and configuration) scales redirect reflected solar radiation toward the interior of the receiver for increased absorptance. Hotter regions within the interior of the receiver can reduce thermal emittance due to reduced local view factors to the environment, and higher concentration ratios can be employed with similar surface irradiances to reduce the effective optical aperture, footprint, and thermal losses. Coupled optical/fluid/thermal models have been developed to evaluate the performance of these designs relative to conventional designs, and meso-scale tests have been performed. Results show that fractal-like structures and geometries can increase the thermal efficiency by several percentage points at both the meso and macro scales, depending on factors such as intrinsic absorptance. The impact was more pronounced for materials with lower intrinsic solar absorptances (<0.9). The goal of this work is to increase the effective solar absorptance of oxidized substrate materials from ~0.9 to 0.95 or greater using these fractal-like geometries without the need for coatings.

  18. Water-related absorption in fibrous diamonds

    NASA Astrophysics Data System (ADS)

    Zedgenizov, D. A.; Shiryaev, A. A.; Kagi, H.; Navon, O.

    2003-04-01

    Cubic and coated diamonds from several localities (Brasil, Canada, Yakutia) were investigated using spectroscopic techniques. Special emphasis was put on investigation of water-related features of transmission Infra-red and Raman spectra. Presence of molecular water is inferred from broad absorption bands in IR at 3420 and 1640 cm-1. These bands were observed in many of the investigated samples. It is likely that molecular water is present in microinclusions in liquid state, since no clear indications of solid H_2O (ice VI-VII, Kagi et al., 2000) were found. Comparison of absorption by HOH and OH vibrations shows that diamonds can be separated into two principal groups: those containing liquid water (direct proportionality of OH and HOH absorption) and those with stronger absorption by OH group. Fraction of diamonds in every group depends on their provenance. There might be positive correlation between internal pressure in microinclusions (determined using quartz barometer, Navon et al., 1988) and affiliation with diamonds containing liquid water. In many cases absorption by HOH vibration is considerably lower than absorption by hydroxyl (OH) group. This may be explained if OH groups are partially present in mineral and/or melt inclusions. This hypothesis is supported by following fact: in diamonds with strong absorption by silicates and other minerals shape and position of the OH band differs from that in diamonds with low absorption by minerals. Moreover, in Raman spectra of individual inclusions sometimes the broad band at 3100 cm-1 is observed. This band is OH-related. In some samples water distribution is not homogeneous. Central part of the diamond usually contains more water than outer parts, but this is not a general rule for all the samples. Water absorption usually correlated with absorption of other components (carbonates, silicates and others). At that fibrous diamonds with relatively high content of silicates are characterized by molecular water. OH

  19. Two-dimensional probe absorption in coupled quantum dots

    NASA Astrophysics Data System (ADS)

    Liu, Ningwu; Zhang, Yan; Kang, Chengxian; Wang, Zhiping; Yu, Benli

    2016-07-01

    We investigate the two-dimensional (2D) probe absorption in coupled quantum dots. It is found that, due to the position-dependent quantum interference effect, the 2D optical absorption spectrum can be easily controlled via adjusting the system parameters. Thus, our scheme may provide some technological applications in solid-state quantum communication.

  20. WATER ABSORPTION FROM GAS VERY NEAR THE MASSIVE PROTOSTAR AFGL 2136 IRS 1

    SciTech Connect

    Indriolo, Nick; Neufeld, D. A.; Seifahrt, A.; Richter, M. J.

    2013-10-10

    We present ground-based observations of the ν{sub 1} and ν{sub 3} fundamental bands of H{sub 2}O toward the massive protostar AFGL 2136 IRS 1, identifying absorption features due to 47 different ro-vibrational transitions between 2.468 μm and 2.561 μm. Analysis of these features indicates the absorption arises in warm (T = 506 ± 25 K), very dense (n(H{sub 2}) > 5 × 10{sup 9} cm{sup –3}) gas, suggesting an origin close to the central protostar. The total column density of warm water is estimated to be N(H{sub 2}O) = (1.02 ± 0.02) × 10{sup 19} cm{sup –2}, giving a relative abundance of N(H{sub 2}O)/N(H{sub 2}) ≈ 10{sup –4}. Our study represents the first extensive use of water vapor absorption lines in the near infrared, and demonstrates the utility of such observations in deriving physical parameters.

  1. DISENTANGLING THE CIRCUMNUCLEAR ENVIRONS OF CENTAURUS A. II. ON THE NATURE OF THE BROAD ABSORPTION LINE

    SciTech Connect

    Espada, D.; Matsushita, S.; Sakamoto, K.; Peck, A. B.; Henkel, C.; Iono, D.; Israel, F. P.; Muller, S.; Petitpas, G.; Pihlstroem, Y.; Taylor, G. B.; Trung, D. V.

    2010-09-01

    We report on atomic gas (H I) and molecular gas (as traced by CO(2-1)) redshifted absorption features toward the nuclear regions of the closest powerful radio galaxy, Centaurus A (NGC 5128). Our H I observations using the Very Long Baseline Array allow us to discern with unprecedented sub-parsec resolution H I absorption profiles toward different positions along the 21 cm continuum jet in the inner 0.''3 (or 5.4 pc). In addition, our CO(2-1) data obtained with the Submillimeter Array probe the bulk of the absorbing molecular gas with little contamination by emission, which was not possible with previous CO single-dish observations. We shed light on the physical properties of the gas in the line of sight with these data, emphasizing the still open debate about the nature of the gas that produces the broad absorption line ({approx}55 km s{sup -1}). First, the broad H I line is more prominent toward the central and brightest 21 cm continuum component than toward a region along the jet at a distance {approx}20 mas (or 0.4 pc) further from the nucleus. This indicates that the broad absorption line arises from gas located close to the nucleus, rather than from diffuse and more distant gas. Second, the different velocity components detected in the CO(2-1) absorption spectrum match well with other molecular lines, such as those of HCO{sup +}(1-0), except the broad absorption line that is detected in HCO{sup +}(1-0) (and most likely related to that of the H I). Dissociation of molecular hydrogen due to the active galactic nucleus seems to be efficient at distances r {approx}< 10 pc, which might contribute to the depth of the broad H I and molecular lines.

  2. Absorption from a multi-layer circumnuclear medium and reflection from the accretion disc in NGC 1365

    NASA Astrophysics Data System (ADS)

    Risaliti, G.

    2016-05-01

    NGC 1365 hosts an X-ray obscured AGN known for both its variable absorption and its relativistic features in the reflection component. Recent simultaneous observations performed by XMM-Newton and NuSTAR caught the source in a rare, nearly unobscured state, revealing the presence of a warm absorber and a neutral, but low column density (∼ 1022 cm-2) absorber, usually not observable due to thicker layers along the line of sight. Here I propose a multi-layer structure of the circumnuclear medium which can explain all the observed absorption states of this source, and their variability properties. Remarkably, despite the spectral complexity due to this multi-component absorber, the relativistic reflection component (and hence the black hole spin) can be unambiguously measured through a time resolved spectroscopic analysis.

  3. Research on absorption test methods of Yb-doped double cladding fiber

    NASA Astrophysics Data System (ADS)

    Wang, Pupu; Li, Rundong; Rong, Liang; Ji, Wei; Gao, Yankun; Jiang, Cong; Gu, Shaoyi

    2016-01-01

    Absorption coefficient is a very useful feature for active fiber. In fiber laser system, the length of active fiber is chosen according to absorption coefficient. And the length of fiber can directly influence the feature of fiber laser. Therefore, how to obtain an accurate absorption coefficient is very important. Because fiber exists re-emission in typical absorption band pumped by power. It is difficult to accurately measure absorption coefficient. The absorption coefficients of Yb-doped double cladding fiber at 975 nm measured by several methods were compared. In conclusion, for the fibers with same length pumped by white light, the absorption coefficient is the highest when cutback only once. Meanwhile, when fibers with different length were measured by the same method, the absorption coefficient is inversely proportional to optical fiber length.

  4. Nasal Absorption of Macromolecules from Powder Formulations and Effects of Sodium Carboxymethyl Cellulose on Their Absorption.

    PubMed

    Tanaka, Akiko; Furubayashi, Tomoyuki; Matsushita, Akifumi; Inoue, Daisuke; Kimura, Shunsuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2016-01-01

    The nasal absorption of macromolecules from powder formulations and the effect of sodium carboxymethyl cellulose (CMC-Na) as a pharmaceutical excipient on their absorption were studied. Model macromolecules were fluorescein isothiocyanate-labeled dextran (average molecular weight of 4.4kDa, FD4) and insulin. The plasma concentration of FD4 after application of the powder containing 50% starch (control) was higher than that after application of the solution, and the absorption from 50% starch powder was enhanced by the substitution of starch with CMC-Na. The fractional absorption of FD4 after administration of the CMC-Na powder formulation was 30% and 40% higher than that after administration from the solution and the starch powder, respectively. The nasal absorption of insulin from the powder and the effect of CMC-Na were similar with those of FD4. The effective absorption of FD4 and insulin after application of powder with CMC-Na could be due to the increase in the nasal residence of FD4 and insulin. No damage in the nasal mucosa or dysfunction of the mucociliary clearance was observed after application of the drug powder and CMC-Na. The present findings indicate that nasal delivery of powder formulations with the addition of CMC-Na as an excipient is a promising approach for improving the nasal absorption of macromolecules. PMID:27598527

  5. Light absorption and morphological properties of soot-containing aerosols observed at an East Asian outflow site, Noto Peninsula, Japan

    NASA Astrophysics Data System (ADS)

    Ueda, Sayako; Nakayama, Tomoki; Taketani, Fumikazu; Adachi, Kouji; Matsuki, Atsushi; Iwamoto, Yoko; Sadanaga, Yasuhiro; Matsumi, Yutaka

    2016-03-01

    The coating of black carbon (BC) with inorganic salts and organic compounds can enhance the magnitude of light absorption by BC. To elucidate the enhancement of light absorption of aged BC particles and its relation to the mixing state and morphology of individual particles, we conducted observations of particles at an Asian outflow site in Noto Peninsula, Japan, in the spring of 2013. Absorption and scattering coefficients at 405, 532, and 781 nm and mass concentrations/mixing states of refractory BC in PM2.5 were measured using a three-wavelength photoacoustic soot spectrometer and a single-particle soot photometer (SP2), respectively, after passage through a thermodenuder (TD) maintained at 300 or 400 °C or a bypass line maintained at room temperature (25 °C). The average enhancement factor of BC light absorption due to coating was estimated by comparing absorption coefficients at 781 nm for particles that with and without passing through the TD at 300 °C and was found to be 1.22. The largest enhancements (> 1.30) were observed under high absorption coefficient periods when the air mass was long-range transported from urban areas in China. Aerosol samples were also analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. The morphological features and mixing states of soot-containing particles of four samples collected during the high absorption events were analyzed by comparing microphotographs before and after the evaporation of beam-sensitive materials by irradiation with a high-density electron beam. The majority of the soot in all samples was found as mixed particles with sulfate-containing spherules or as clusters of such spherules. For samples showing high enhancement (> 1.30) of BC light absorption, the TEM showed that the internally mixed soot-containing particles tended to have a more spherical shape and to be thickly coated. The SP2 measurements also suggested that the proportion of thickly coated

  6. Light absorption and morphological properties of soot-containing aerosols observed at an East Asian outflow site, Noto Peninsula, Japan

    NASA Astrophysics Data System (ADS)

    Ueda, S.; Nakayama, T.; Taketani, F.; Adachi, K.; Matsuki, A.; Iwamoto, Y.; Sadanaga, Y.; Matsumi, Y.

    2015-09-01

    The coating of black carbon (BC) with inorganic salts and organic compounds can enhance the magnitude of light absorption by BC. To elucidate the enhancement of light absorption of aged BC particles and its relation to the mixing state and morphology of individual particles, we conducted observations of particles at an Asian outflow site in Noto Peninsula, Japan, in the spring of 2013. Absorption and scattering coefficients at 405, 532, and 781 nm and mass concentrations/mixing states of refractory-BC in PM2.5 were measured using a three-wavelength photoacoustic soot spectrometer and a single-particle soot photometer (SP2), respectively, after passage through a heater maintained at 300 or 400 °C or a bypass line maintained at room temperature (25 °C). The average enhancement of BC light absorption due to coating was estimated by comparing absorption coefficients at 781 nm for particles that with and without passing through the heater and was found to be 22-23 %. The largest enhancements (> 30 %) were observed under high absorption coefficient conditions when the air mass was long-range transported from urban areas in China. Aerosol samples were also analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. The morphological features and mixing states of soot-containing particles of four samples collected during the high absorption coefficient events were analyzed by comparing microphotographs before and after the evaporation of beam-sensitive materials by irradiation with a high density electron beam. The majority of the soot in all samples was found as mixed particles with spherical sulfate or as clusters of sulfate spherules. For samples showing high enhancement (> 30 %) of BC light absorption, TEM showed that the internally mixed soot-containing particles tended to have a more spherical shape and to be embedded into the sulfate. The SP2 measurements also suggested that the proportion of thickly-coated soot was

  7. Evaluation wavelength range mapping, a tool to optimize the evaluation window in differential absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Vogel, L.; Sihler, H.; Lampel, J.; Wagner, T.; Platt, U.

    2012-04-01

    Optical remote sensing via Differential Optical Absorption Spectroscopy (DOAS) has become a standard technique to assess various trace gases in the atmosphere. Measurement instruments are usually classified into active instruments applying an artificial light source and passive instruments using natural light sources, e.g., scattered or direct sunlight. Platforms range from ground based to satellites and trace gases are studied in all kinds of different environments. Naturally, the evaluation of gathered spectra needs to be tuned to each specific case and trace gas of interest due to the wide range of measurement conditions, atmospheric compositions and instruments used. A well chosen evaluation wavelength range is crucial to the DOAS technique. It should be as large as possible and include the largest differential absorption features of the trace gas of interest in order to maximize sensitivity. However, the differential optical densities of other absorbers should be minimized in order to prevent interferences between different absorption cross sections. Furthermore, instrumental specific features and wavelength dependent radiative transfer effects may have malicious effects and lead to erroneous values. Usually a compromise needs to be found depending on the conditions at hand. Evaluation wavelength range mapping is an easily applied tool to visualize wavelength depending evaluation features of DOAS and to find the optimal retrieval wavelength range. As an example, synthetic spectra are studied which simulate passive DOAS measurements of stratospheric bromine monoxide (BrO) by Zenith-DOAS and Multi-Axis DOAS (MAX-DOAS) measurements of BrO in volcanic plumes. The influence of the I0-effect and the Ring-effect on the respective retrievals are demonstrated. However, due to the general nature of the tool it is applicable to any DOAS measurement and the technique also allows to study any other wavelength dependent influences on retrieved trace gas columns.

  8. Development of a Near-Ir Cavity Enhanced Absorption Spectrometer for the Detection of Atmospheric Oxidation Products and Organoamines

    NASA Astrophysics Data System (ADS)

    Eddingsaas, Nathan C.; Jewell, Breanna; Thurnherr, Emily

    2014-06-01

    An estimated 10,000 to 100,000 different compounds have been measured in the atmosphere, each one undergoes many oxidation reactions that may or may not degrade air quality. To date, the fate of even some of the most abundant hydrocarbons in the atmosphere is poorly understood. One difficulty is the detection of atmospheric oxidation products that are very labile and decompose during analysis. To study labile species under atmospheric conditions, a highly sensitive, non-destructive technique is needed. Here we describe a near-IR incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) setup that we are developing to meet this end. We have chosen to utilize the near-IR, where vibrational overtone absorptions are observed, due to the clean spectral windows and better spectral separation of absorption features. In one spectral window we can simultaneously and continuously monitor the composition of alcohols, hydroperoxides, and carboxylic acids in an air mass. In addition, we have used our CEAS setup to detect organoamines. The long effective path length of CEAS allows for low detection limits, even of the overtone absorption features, at ppb and ppt levels.

  9. 69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER UNDER CONSTRUCTION. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  10. Chaotic systems with absorption.

    PubMed

    Altmann, Eduardo G; Portela, Jefferson S E; Tél, Tamás

    2013-10-01

    Motivated by applications in optics and acoustics we develop a dynamical-system approach to describe absorption in chaotic systems. We introduce an operator formalism from which we obtain (i) a general formula for the escape rate κ in terms of the natural conditionally invariant measure of the system, (ii) an increased multifractality when compared to the spectrum of dimensions D(q) obtained without taking absorption and return times into account, and (iii) a generalization of the Kantz-Grassberger formula that expresses D(1) in terms of κ, the positive Lyapunov exponent, the average return time, and a new quantity, the reflection rate. Simulations in the cardioid billiard confirm these results. PMID:24138240

  11. Pathways of iron absorption.

    PubMed

    Conrad, Marcel E; Umbreit, Jay N

    2002-01-01

    Iron is vital for all living organisms but excess iron can be lethal because it facilitates free radical formation. Thus iron absorption is carefully regulated to maintain an equilibrium between absorption and body loss of iron. In countries where meat is a significant part of the diet, most body iron is derived from dietary heme because heme binds few of the dietary chelators that bind inorganic iron. Uptake of heme into enterocytes occurs as a metalloporphyrin in an endosomal process. Intracellular iron is released from heme by heme oxygenase to enter plasma as inorganic iron. Ferric iron is absorbed via a beta(3) integrin and mobilferrin pathway (IMP) which is unshared with other nutritional metals. Ferrous iron uptake is facilitated by a DMT-1 pathway which is shared with manganese. In the iron deficient gut, large quantities of both mobilferrin and DMT-1 are found in goblet cells and intraluminal mucins suggesting that they are secreted with mucin into the intestinal lumen to bind iron to facilitate uptake by the cells. In the cytoplasm, IMP and DMT associate in a large protein complex called paraferritin which serves as a ferrireductase. Paraferritin solublizes iron binding proteins and reduces iron to make iron available for production of iron containing proteins such as heme. Iron uptake by intestinal absorptive cells is regulated by the iron concentration within the cell. Except in hemochromatosis it remains in equilibrium with total body stores via transferrin receptors on the basolateral membrane of absorptive cells. Increased intracellular iron either up-regulates or satiates iron binding proteins on regulatory proteins to alter their location in the intestinal mucosa. PMID:12547224

  12. Absorption spectrum of DNA for wavelengths greater than 300 nm

    SciTech Connect

    Sutherland, J.C.; Griffin, K.P.

    1981-06-01

    Although DNA absorption at wavelengths greater than 300 nm is much weaker than that at shorter wavelengths, this absorption seems to be responsible for much of the biological damage caused by solar radiation of wavelengths less than 320 nm. Accurate measurement of the absorption spectrum of DNA above 300 nm is complicated by turbidity characteristic of concentrated solutions of DNA. We have measured the absorption spectra of DNA from calf thymus, Clostridium perfringens, Escherichia coli, Micrococcus luteus, salmon testis, and human placenta using procedures which separate optical density due to true absorption from that due to turbidity. Above 300 nm, the relative absorption of DNA increases as a function of guanine-cytosine content, presumably because the absorption of guanine is much greater than the absorption of adenine at these wavelengths. This result suggests that the photophysical processes which follow absorption of a long-wavelength photon may, on the average, differ from those induced by shorter-wavelength photons. It may also explain the lower quantum yield for the killing of cells by wavelengths above 300 nm compared to that by shorter wavelengths.

  13. Aerosol optical absorption measurements with photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Wang, Lei; Liu, Qiang; Wang, Guishi; Tan, Tu; Zhang, Weijun; Chen, Weidong; Gao, Xiaoming

    2015-04-01

    Many parameters related to radiative forcing in climate research are known only with large uncertainties. And one of the largest uncertainties in global radiative forcing is the contribution from aerosols. Aerosols can scatter or absorb the electromagnetic radiation, thus may have negative or positive effects on the radiative forcing of the atmosphere, respectively [1]. And the magnitude of the effect is directly related to the quantity of light absorbed by aerosols [2,3]. Thus, sensitivity and precision measurement of aerosol optical absorption is crucial for climate research. Photoacoustic spectroscopy (PAS) is commonly recognized as one of the best candidates to measure the light absorption of aerosols [4]. A PAS based sensor for aerosol optical absorption measurement was developed. A 532 nm semiconductor laser with an effective power of 160 mW was used as a light source of the PAS sensor. The PAS sensor was calibrated by using known concentration NO2. The minimum detectable optical absorption coefficient (OAC) of aerosol was determined to be 1 Mm-1. 24 hours continues measurement of OAC of aerosol in the ambient air was carried out. And a novel three wavelength PAS aerosol OAC sensor is in development for analysis of aerosol wavelength-dependent absorption Angstrom coefficient. Reference [1] U. Lohmann and J. Feichter, Global indirect aerosol effects: a review, Atmos. Chem. Phys. 5, 715-737 (2005) [2] M. Z. Jacobson, Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols, Nature 409, 695-697 (2001) [3] V. Ramanathan and G. Carmichae, Global and regional climate changes due to black carbon, nature geoscience 1, 221-227 (2008) [4] W.P Arnott, H. Moosmuller, C. F. Rogers, T. Jin, and R. Bruch, Photoacoustic spectrometer for measuring light absorption by aerosol: instrument description. Atmos. Environ. 33, 2845-2852 (1999).

  14. Cloud geometry effects on atmospheric solar absorption

    SciTech Connect

    Fu, Q.; Cribb, M.C.; Barker, H.W.; Krueger, S.K.; Grossman, A.

    2000-04-15

    A 3D broadband solar radiative transfer scheme is formulated by integrating a Monte Carlo photon transport algorithm with the Fu-Liou radiation model. It is applied to fields of tropical mesoscale convective clouds and subtropical marine boundary layer clouds that were generated by a 2D cloud-resolving model. The effects of cloud geometry on the radiative energy budget are examined by comparing the full-resolution Monte Carlo results with those from the independent column approximation (ICA) that applies the plane-parallel radiation model to each column. For the tropical convective cloud system, it is found that cloud geometry effects always enhance atmospheric solar absorption regardless of solar zenith angle. In a large horizontal domain (512 km), differences in domain-averaged atmospheric absorption between the Monte Carlo and the ICA are less than 4 W m{sup {minus}2} in the daytime. However, for a smaller domain (e.g., 75 km) containing a cluster of deep convective towers, domain-averaged absorption can be enhanced by more than 20 W m{sup {minus}2}. For a subtropical marine boundary layer cloud system during the stratus-to-cumulus transition, calculations show that the ICA works very well for domain-averaged fluxes of the stratocumulus cloud fields even for a very small domain (4.8 km). For the trade cumulus cloud field, the effects of cloud sides and horizontal transport of photons become more significant. Calculations have also been made for both cloud systems including black carbon aerosol and a water vapor continuum. It is found that cloud geometry produces no discernible effects on the absorption enhancement due to the black carbon aerosol and water vapor continuum. The current study indicates that the atmospheric absorption enhancement due to cloud-related 3D photon transport is small. This enhancement could not explain the excess absorption suggested by recent studies.

  15. UV laser long-path absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Dorn, Hans-Peter; Brauers, Theo; Neuroth, Rudolf

    1994-01-01

    Long path Differential Optical Absorption Spectroscopy (DOAS) using a picosecond UV laser as a light source was developed in our institute. Tropospheric OH radicals are measured by their rotational absorption lines around 308 nm. The spectra are obtained using a high resolution spectrograph. The detection system has been improved over the formerly used optomechanical scanning device by application of a photodiode array which increased the observed spectral range by a factor of 6 and which utilizes the light much more effectively leading to a considerable reduction of the measurement time. This technique provides direct measurements of OH because the signal is given by the product of the absorption coefficient and the OH concentration along the light path according to Lambert-Beers law. No calibration is needed. Since the integrated absorption coefficient is well known the accuracy of the measurement essentially depends on the extent to which the OH absorption pattern can be detected in the spectra. No interference by self generated OH radicals in the detection lightpath has been observed. The large bandwidth (greater than 0.15 nm) and the high spectral resolution (1.5 pm) allows absolute determination of interferences by other trace gas absorptions. The measurement error is directly accessible from the absorption-signal to baseline-noise ratio in the spectra. The applicability of the method strongly depends on visibility. Elevated concentrations of aerosols lead to considerable attenuation of the laser light which reduces the S/N-ratio. In the moderately polluted air of Julich, where we performed a number of OH measurement spectra. In addition absorption features of unidentified species were frequently detected. A quantitative deconvolution even of the known species is not easy to achieve and can leave residual structures in the spectra. Thus interferences usually increase the noise and deteriorate the OH detection sensitivity. Using diode arrays for sensitive

  16. Relic Neutrino Absorption Spectroscopy

    SciTech Connect

    Eberle, b

    2004-01-28

    Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10{sup 21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m{sub {nu}} 0.1 eV for the lightest neutrino. With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably.

  17. GAS AND DUST ABSORPTION IN THE DoAr 24E SYSTEM

    SciTech Connect

    Kruger, Andrew J.; Richter, Matthew J.; Seifahrt, Andreas; Carr, John S.; Najita, Joan R.; Moerchen, Margaret M.; Doppmann, Greg W.

    2012-11-20

    We present findings for DoAr 24E, a binary system that includes a classical infrared companion. We observed the DoAr 24E system with the Spitzer Infrared Spectrograph (IRS), with high-resolution, near-infrared spectroscopy of CO vibrational transitions, and with mid-infrared imaging. The source of high extinction toward infrared companions has been an item of continuing interest. Here we investigate the disk structure of DoAr 24E using the column densities, temperature, and velocity profiles of two CO absorption features seen toward DoAr 24Eb. We model the spectral energy distributions found using T-ReCS imaging and investigate the likely sources of extinction toward DoAr 24Eb. We find the lack of silicate absorption and small CO column density toward DoAr 24Eb suggest that the mid-infrared continuum is not as extinguished as the near-infrared, possibly due to the mid-infrared originating from an extended region. This, along with the velocity profile of the CO absorption, suggests that the source of high extinction is likely due to a disk or disk wind associated with DoAr 24Eb.

  18. CO2 Capture from Flue Gas by Phase Transitional Absorption

    SciTech Connect

    Liang Hu

    2009-06-30

    A novel absorption process called Phase Transitional Absorption was invented. What is the Phase Transitional Absorption? Phase Transitional Absorption is a two or multi phase absorption system, CO{sub 2} rich phase and CO{sub 2} lean phase. During Absorption, CO{sub 2} is accumulated in CO{sub 2} rich phase. After separating the two phases, CO{sub 2} rich phase is forward to regeneration. After regeneration, the regenerated CO{sub 2} rich phase combines CO{sub 2} lean phase to form absorbent again to complete the cycle. The advantage for Phase Transitional Absorption is obvious, significantly saving on regeneration energy. Because CO{sub 2} lean phase was separated before regeneration, only CO{sub 2} rich phase was forward to regeneration. The absorption system we developed has the features of high absorption rate, high loading and working capacity, low corrosion, low regeneration heat, no toxic to environment, etc. The process evaluation shows that our process is able to save 80% energy cost by comparing with MEA process.

  19. Enhanced absorption cycle computer model. Final report

    SciTech Connect

    Grossman, G.; Wilk, M.

    1993-09-01

    Absorption heat pumps have received renewed and increasing attention in the past two decades. The rising cost of electricity has made the particular features of this heat-powered cycle attractive for both residential and industrial applications. Solar-powered absorption chillers, gas-fired domestic heat pumps, and waste-heat-powered industrial temperatures boosters are a few of the applications recently subjected to intensive research and development. The absorption heat pump research community has begun to search for both advanced cycles in various multistage configurations and new working fluid combinations with potential for enhanced performance and reliability. The development of working absorptions systems has created a need for reliable and effective system simulations. A computer code has been developed for simulation of absorption systems at steady state in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the system`s components and property subroutines containing thermodynamic properties of the working fluids. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnections. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system, and the heat duty at each unit, from which the coefficient of performance (COP) may be determined. This report describes the code and its operation, including improvements introduced into the present version. Simulation results are described for LiBr-H{sub 2}O triple-effect cycles, LiCl-H{sub 2}O solar-powered open absorption cycles, and NH{sub 3}-H{sub 2}O single-effect and generator-absorber heat exchange cycles. An appendix contains the User`s Manual.

  20. Saturnian trapped radiation and its absorption by satellites and rings: the first results from Pioneer 11

    SciTech Connect

    Simpson, J.A.; Bastian, T.S.; Chenette, D.L.; Lentz, G.A.; McKibben, R.B.; Pyle, K.R.; Tuzzolino, A.J.

    1980-01-25

    Electrons and protons accelerated and trapped in a Saturnian magnetic field were found by the University of Chicago experiments on Pioneer 11 within 20 Saturn radii (R/sub S/) of the planet. In the innermost regions, strong absorption effects due to satellites and ring material were observed, and from approx.4 R/sub S/ inwards to the outer edge of the A ring at 2.30 R/sub S/ (where the radiation is absorbed), the intensity distributions of protons (greater than or equal to 0.5 million electron volts) and electrons (2 to 20 million electron volts) were axially symmetric, consistent with a centered dipole aligned with the planetary rotation axis. The maximum fluxes observed for protons (> 35 million electron volts and for electrons > 3.4 million electron volts) were 3 x 10/sup 4/ and 3 x 10/sup 6/ per square centimeter per second, respectively. Absorption of radiation by Mimas provides a means of estimating the radial diffusion coefficient for charged particle transport. However, the rapid flux increases observed between absorption features raise new questions concerning the physics of charged-particle transport and acceleration. An absorption feature 2.5 R/sub S/ has led to the discovery of a previously unknown satellite with a diameter of greater than or equal to 200 kilometers, semimajor axis of 2.51 R/sub S/, and eccentricity of 0.013. Radiation absorption features that suggest a nonuniform distribution of matter around Saturn have also been found from 2.34 to 2.36 R/sub S/, near the position of the F ring discovered by the Pioneer imaging experiment. Beneath the A, B, and C rings a low flux of high-energy electrons was observed. It is concluded that the inner Saturn magnetosphere, because of its near-axial symmetry and the many discrete radiation absorption regions, offers a unique opportunity to study the acceleration and transport of charged particles in a planetary magnetic field. 5 figures, 2 tables

  1. Corrosion Problems in Absorption Chillers

    ERIC Educational Resources Information Center

    Stetson, Bruce

    1978-01-01

    Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

  2. Exciton absorption of entangled photons in semiconductor quantum wells

    NASA Astrophysics Data System (ADS)

    Rodriguez, Ferney; Guzman, David; Salazar, Luis; Quiroga, Luis; Condensed Matter Physics Group Team

    2013-03-01

    The dependence of the excitonic two-photon absorption on the quantum correlations (entanglement) of exciting biphotons by a semiconductor quantum well is studied. We show that entangled photon absorption can display very unusual features depending on space-time-polarization biphoton parameters and absorber density of states for both bound exciton states as well as for unbound electron-hole pairs. We report on the connection between biphoton entanglement, as quantified by the Schmidt number, and absorption by a semiconductor quantum well. Comparison between frequency-anti-correlated, unentangled and frequency-correlated biphoton absorption is addressed. We found that exciton oscillator strengths are highly increased when photons arrive almost simultaneously in an entangled state. Two-photon-absorption becomes a highly sensitive probe of photon quantum correlations when narrow semiconductor quantum wells are used as two-photon absorbers. Research funds from Facultad de Ciencias, Universidad de los Andes

  3. Acoustic Absorption Characteristics of People.

    ERIC Educational Resources Information Center

    Kingsbury, H. F.; Wallace, W. J.

    1968-01-01

    The acoustic absorption characteristics of informally dressed college students in typical classroom seating are shown to differ substantially from data for formally dressed audiences in upholstered seating. Absorption data, expressed as sabins per person or absorption coefficient per square foot, shows that there is considerable variation between…

  4. Acetaminophen (paracetamol) oral absorption and clinical influences.

    PubMed

    Raffa, Robert B; Pergolizzi, Joseph V; Taylor, Robert; Decker, John F; Patrick, Jeffrey T

    2014-09-01

    Acetaminophen (paracetamol) is a widely used nonopioid, non-NSAID analgesic that is effective against a variety of pain types, but the consequences of overdose can be severe. Because acetaminophen is so widely available as a single agent and is increasingly being formulated in fixed-ratio combination analgesic products for the potential additive or synergistic analgesic effect and/or reduced adverse effects, accidental cumulative overdose is an emergent concern. This has rekindled interest in the sites, processes, and pharmacokinetics of acetaminophen oral absorption and the clinical factors that can influence these. The absorption of oral acetaminophen occurs primarily along the small intestine by passive diffusion. Therefore, the rate-limiting step is the rate of gastric emptying into the intestines. Several clinical factors can affect absorption per se or the rate of gastric emptying, such as diet, concomitant medication, surgery, pregnancy, and others. Although acetaminophen does not have the abuse potential of opioids or the gastrointestinal bleeding or organ adverse effects of NSAIDs, excess amounts can produce serious hepatic injury. Thus, an understanding of the sites and features of acetaminophen absorption--and how they might be influenced by factors encountered in clinical practice--is important for pain management using this agent. It can also provide insight for design of formulations that would be less susceptible to clinical variables. PMID:26013309

  5. Christiansen effect in disperse systems with resonant absorption

    SciTech Connect

    Zimnyakov, D A; Isaeva, Elmira A; Isaeva, A A

    2012-01-31

    We discuss the results of experimental studies of competition of absorption and scattering of laser radiation propagating in dispersive media with resonant absorption. As media under study, use is made of a suspension of polystyrene particles in solutions of rhodamine 6G in ethylene glycol probed by laser light with a wavelength of 532 nm. It is found that an increase in the dye concentration leads to an increase in optical transmittance of suspensions and an increase in speckle modulation of the forward-scattered radiation. We interpret these features as a manifestation of Christiansen effect in disperse systems with resonance absorption.

  6. Scattering with absorptive interaction

    NASA Astrophysics Data System (ADS)

    Cassing, W.; Stingl, M.; Weiguny, A.

    1982-07-01

    The S matrix for a wide class of complex and nonlocal potentials is studied, with special attention given to the motion of singularities in the complex k plane as a function of the imaginary coupling strength. Modifications of Levinson's theorem are obtained and discussed. Analytic approximations to the S matrix in the vicinity of narrow resonances are exhibited and compared to numerical results of resonating-group calculations. The problem of defining resonances in the case of complex interactions is discussed, making contact with the usual analysis of scattering in terms of Argand diagrams. NUCLEAR REACTIONS Scattering theory, S matrix for absorptive potentials.

  7. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, M.E.; Bien, F.; Bernstein, L.S.

    1986-12-09

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

  8. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, Michael E.; Bien, Fritz; Bernstein, Lawrence S.

    1986-01-01

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined.

  9. The absorption of polymeric composites

    NASA Astrophysics Data System (ADS)

    Řídký, R.; Popovič, M.; Rolc, S.; Drdlová, M.; Krátký, J.

    2016-06-01

    An absorption capacity of soft, viscoelastic materials at high strain rates is important for wide range of practical applications. Nowadays there are many variants of numerical models suitable for this kind of analysis. The main difficulty is in selection of the most realistic numerical model and a correct setup of many unknown material constants. Cooperation between theoretical simulations and real testing is next crucial point in the investigation process. Standard open source material database offer material properties valid for strain rates less than 250 s-1. There are experiments suitable for analysis of material properties with strain rates close to 2000 s-1. The high strain-rate characteristics of a specific porous blast energy absorbing material measured by modified Split Hopkinson Pressure Bar apparatus is presented in this study. Testing these low impedance materials using a metallic split Hopkinson pressure bar setup results in poor signal to noise ratios due to impedance mismatching. These difficulties are overcome by using polymeric Hopkinson bars. Conventional Hopkinson bar analysis cannot be used on the polymeric bars due to the viscoelastic nature of the bar material. One of the possible solution leads to complex and frequency depended Young modulus of testing bars material. This testing technique was applied to materials composed of porous glass/ceramic filler and polymeric binder, with density of 125 - 300 kg/m3 and particle size in range of 50 µm - 2 mm. The achieved material model was verified in practical application of sandwich structure includes polymeric composites under a blast test.

  10. Papilledema Due to Mirtazapine

    PubMed Central

    Ceylan, Mehmet Emin; Evrensel, Alper; Cömert, Gökçe

    2016-01-01

    Background: Mirtazapine is a tetracyclic antidepressant that enhances both noradrenergic and serotonergic transmission. The most common cause of papilledema is increased intracranial pressure due to brain tumor. Also it may occur as a result of idiopathic intracranial hypertension (IIH, pseudo tumor cerebri). Moreover, papilledema may also develop due to retinitis, vasculitis, Graves’ disease, hypertension, leukemia, lymphoma, diabetes mellitus and radiation. Case Report: In this article, a patient who developed papilledema while under treatment with mirtazapine (30 mg/day) for two years and recovered with termination of mirtazapine treatment was discussed to draw the attention of clinicians to this side effect of mirtazapine. Conclusion: Idiopathic intracranial hypertension and papilledema due to psychotropic drugs has been reported in the literature. Mirtazapine may rarely cause peripheral edema. However, papilledema due to mirtazapine has not been previously reported. Although papilledema is a very rare side effect of an antidepressant treatment, fundoscopic examinations of patients must be performed regularly. PMID:27308085

  11. Connecting the Silicate Dust and Gas Properties of Distant Galaxies Using Quasar Absorption Systems

    NASA Astrophysics Data System (ADS)

    Aller, Monique C.; Kulkarni, Varsha P.; York, Donald G.; Welty, Daniel E.; Vladilo, Giovanni; Som, Debopam; Lackey, Kyle; Dwek, Eli; Beiranvand, Nassim; Morrison, Sean

    2016-01-01

    We present recent results from our program investigating the silicate dust properties in distant galaxies using quasar absorption systems. The dust and gas properties of distant galaxies can be characterized by studying the absorption features produced by them along the sightlines to luminous background quasars. Based on our prior finding that silicate dust absorption in z<1.5 quasar absorption systems exhibits a range of optical depths and absorption feature substructures, suggestive of silicate grain property variations, we are investigating silicate dust absorption in quasar absorption systems toward quasars with archival Spitzer Space Telescope Infrared Spectrograph (IRS) spectra. We present our measurements of the 10 and/or 18 micron silicate dust absorption feature(s) in these systems, and discuss constraints on the grain properties, such as composition and crystallinity, based on the shape and substructure present in these features. We also investigate the correlations between the silicate dust properties and the reddening. Connections between the silicate dust and gas phase metal absorption properties can also be probed for some of our targets with archival ground-based spectra. These relationships will yield valuable insights into the star formation history and evolution of metals and dust. This work is supported by NASA through ADAP grant NNX14AG74G and by an award issued by JPL/Caltech, and from US-NSF grant AST-1108830 to the University of South Carolina.

  12. Coupled absorption filters for thermal detectors.

    PubMed

    Wang, Yuyan; Potter, Benjamin J; Talghader, Joseph J

    2006-07-01

    A resonant absorption cavity that couples long-wavelength infrared (LWIR) light into a movable plate has been demonstrated for thermal detectors, especially microbolometers. Each device is continuously tunable over 8.7-11.1 microm by using electrostatic actuation with voltages from 0 to 42 V. The width of the resonance is relatively broad, approximately 1.5 microm, to match the large widths of many spectral features in the LWIR. At an actuation voltage of 45 V, the device switches into a broadband mode with an absorption width of 2.83 microm. This latter mode is used to enhance sensitivity in low-light situations in which little spectral information is present. PMID:16770393

  13. Overview-absorption/Rankine solar cooling program

    NASA Astrophysics Data System (ADS)

    Wahlig, M.; Heitz, A.; Boyce, B.

    1980-03-01

    The tasks being performed in the absorption and Rankine program areas run the gamut from basic work on fluids to development of chillers and chiller components, to field and reliability testing of complete cooling systems. In the absorption program, there are six current and five essentially completed projects. In the Rankine program, there are five current projects directly supported by DOE, and three projects funded through and managed by NASA/MSFC (Manned Space Flight Center, Huntsville, Alabama). The basic features of these projects are discussed. The systems under development in five of these current projects were selected for field testing in the SOLERAS program, a joint US-Saudi Arabian enterprise. Some technical highlights of the program are presented.

  14. [Plant Spectral Discrimination Based on Phenological Features].

    PubMed

    Zhang, Lei; Zhao, Jian-long; Jia, Kun; Li, Xiao-song

    2015-10-01

    Spectral analysis plays a significant role onplant characteristic identification and mechanism recognition, there were many papers published on the aspects of absorption features in the spectra of chlorophyll and moisture, spectral analysis onvegetation red edge effect, spectra profile feature extraction, spectra profile conversion, vegetation leaf structure and chemical composition impacts on the spectra in past years. However, fewer researches issued on spectral changes caused by plant seasonal changes of life form, chlorophyll, leaf area index. This paper studied on spectral observation of 11 plants of various life form, plant leaf structure and its size, phenological characteristics, they include deciduous forest with broad vertical leaf, needle leaf evergreen forest, needle leaf deciduous forest, deciduous forest with broadflat leaf, high shrub with big leaf, high shrub with little leaf, deciduous forest with broad little leaf, short shrub, meadow, steppe and grass. Field spectral data were observed with SVC-HR768 (Spectra Vista company, USA), the band width covers 350-2 500 nm, spectral resolution reaches 1-4 nm. The features of NDVI, spectral maximum absorption depth in green band, and spectral maximum absorption depth in red band were measured after continuum removal processing, the mean, amplitude and gradient of these features on seasonal change profile were analyzed, meanwhile, separability research on plant spectral feature of growth period and maturation period were compared. The paper presents a calculation method of separability of vegetation spectra which consider feature spatial distances. This index is carried on analysis of the vegetation discrimination. The results show that: the spectral features during plant growth period are easier to distinguish than them during maturation period. With the same features comparison, plant separability of growth period is 3 points higher than it during maturation period. The overall separabilityof vegetation

  15. The HI absorption "Zoo"

    NASA Astrophysics Data System (ADS)

    Geréb, K.; Maccagni, F. M.; Morganti, R.; Oosterloo, T. A.

    2015-03-01

    We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis on the radio sources, while here we characterize the absorption spectra of the individual detections using the recently presented busy function. The H I absorption spectra show a broad variety of widths, shapes, and kinematical properties. The full width half maximum (FWHM) of the busy function fits of the detected H I lines lies in the range 32 km s-1absorption (FW20) lies in the range 63 km s-1 200 km s-1). We study the kinematical and radio source properties of each group, with the goal of identifying different morphological structures of H I. Narrow lines mostly lie at the systemic velocity and are likely produced by regularly rotating H I disks or gas clouds. More H I disks can be present among galaxies with lines of intermediate widths; however, the H I in these sources is more unsettled. We study the asymmetry parameter and blueshift/redshift distribution of the lines as a function of their width. We find a trend for which narrow profiles are also symmetric, while broad lines are the most asymmetric. Among the broadest lines, more lines appear blueshifted than redshifted, similarly to what was found by previous studies. Interestingly, symmetric broad lines are absent from the sample. We argue that if a profile is broad, it is also asymmetric and shifted relative to the systemic velocity because it is tracing unsettled H I gas. In particular, besides three of the broadest (up to FW20 = 825 km s-1

  16. Improved self-absorption correction for extended x-ray absorption fine-structure measurements

    SciTech Connect

    Booth, C.H.; Bridges, F.

    2003-06-04

    Extended x-ray absorption fine-structure (EXAFS) data collected in the fluorescence mode are susceptible to an apparent amplitude reduction due to the self-absorption of the fluorescing photon by the sample before it reaches a detector. Previous treatments have made the simplifying assumption that the effect of the EXAFS on the correction term is negligible, and that the samples are in the thick limit. We present a nearly exact treatment that can be applied for any sample thickness or concentration, and retains the EXAFS oscillations in the correction term.

  17. PROBING THE '30 {mu}m' FEATURE: LESSONS FROM EXTREME CARBON STARS

    SciTech Connect

    Messenger, Stephen J.; Speck, Angela; Volk, Kevin E-mail: speckan@missouri.edu

    2013-02-20

    Some carbon-rich evolved stars exhibit a very prominent spectral feature at {approx}{sup 3}0 {mu}m''. The C-rich nature of these objects suggests that the carrier is a sulfide, carbide, or other substance apt to form in a reducing environment. However, the carrier of this spectral feature remains disputed, with magnesium sulfide (MgS) as the most favored candidate. In order to investigate the carrier of the {sup 3}0 {mu}m'' feature further, we have taken a dual approach, studying both laboratory and observational data. In order to obtain a homogeneous sample, we studied the {sup 3}0 {mu}m'' feature observed in the spectra of galactic extreme carbon stars that exhibit the 11 {mu}m SiC absorption feature. Thus, we avoid potential differences in the target objects that could contribute to the observed differences in the shape, position, and strength of the {sup 3}0 {mu}m'' feature. In addition, we analyzed the shape and position of the {sup 3}0 {mu}m'' features for a range of sulfide minerals for which laboratory data exist. Our study of observed astronomical features shows a range of shapes and positions for the {sup 3}0 {mu}m'' feature despite similarities in the source objects. The nature of our sample argues against grain processing or temperature differences due to hardening of the stellar radiation field with evolution. While there are very few correlations between spectral parameters for our sample, the peak positions of the {approx}11 {mu}m absorption and 30 {mu}m emission features do correlate, and these peak positions correlate with the modeled optical depth. These correlations suggest that the carriers of the observable spectral features are closely related to one another and to the density/pressure in the dust formation zone. Furthermore, we suggest that the blue-broadening of the 11 {mu}m feature cannot be attributed to SiS{sub 2} based on existing laboratory spectra, but further lab work is needed to investigate the effect of increasing oxidation.

  18. Probing the "30 μm" Feature: Lessons from Extreme Carbon Stars

    NASA Astrophysics Data System (ADS)

    Messenger, Stephen J.; Speck, Angela; Volk, Kevin

    2013-02-01

    Some carbon-rich evolved stars exhibit a very prominent spectral feature at ~"30 μm." The C-rich nature of these objects suggests that the carrier is a sulfide, carbide, or other substance apt to form in a reducing environment. However, the carrier of this spectral feature remains disputed, with magnesium sulfide (MgS) as the most favored candidate. In order to investigate the carrier of the "30 μm" feature further, we have taken a dual approach, studying both laboratory and observational data. In order to obtain a homogeneous sample, we studied the "30 μm" feature observed in the spectra of galactic extreme carbon stars that exhibit the 11 μm SiC absorption feature. Thus, we avoid potential differences in the target objects that could contribute to the observed differences in the shape, position, and strength of the "30 μm" feature. In addition, we analyzed the shape and position of the "30 μm" features for a range of sulfide minerals for which laboratory data exist. Our study of observed astronomical features shows a range of shapes and positions for the "30 μm" feature despite similarities in the source objects. The nature of our sample argues against grain processing or temperature differences due to hardening of the stellar radiation field with evolution. While there are very few correlations between spectral parameters for our sample, the peak positions of the ~11 μm absorption and 30 μm emission features do correlate, and these peak positions correlate with the modeled optical depth. These correlations suggest that the carriers of the observable spectral features are closely related to one another and to the density/pressure in the dust formation zone. Furthermore, we suggest that the blue-broadening of the 11 μm feature cannot be attributed to SiS2 based on existing laboratory spectra, but further lab work is needed to investigate the effect of increasing oxidation.

  19. Differential optoacoustic absorption detector

    NASA Technical Reports Server (NTRS)

    Shumate, M. S. (Inventor)

    1978-01-01

    A differential optoacoustic absorption detector employed two tapered cells in tandem or in parallel. When operated in tandem, two mirrors were used at one end remote from the source of the beam of light directed into one cell back through the other, and a lens to focus the light beam into the one cell at a principal focus half way between the reflecting mirror. Each cell was tapered to conform to the shape of the beam so that the volume of one was the same as for the other, and the volume of each received maximum illumination. The axes of the cells were placed as close to each other as possible in order to connect a differential pressure detector to the cells with connecting passages of minimum length. An alternative arrangement employed a beam splitter and two lenses to operate the cells in parallel.

  20. Analyzing Water's Optical Absorption

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A cooperative agreement between World Precision Instruments (WPI), Inc., and Stennis Space Center has led the UltraPath(TM) device, which provides a more efficient method for analyzing the optical absorption of water samples at sea. UltraPath is a unique, high-performance absorbance spectrophotometer with user-selectable light path lengths. It is an ideal tool for any study requiring precise and highly sensitive spectroscopic determination of analytes, either in the laboratory or the field. As a low-cost, rugged, and portable system capable of high- sensitivity measurements in widely divergent waters, UltraPath will help scientists examine the role that coastal ocean environments play in the global carbon cycle. UltraPath(TM) is a trademark of World Precision Instruments, Inc. LWCC(TM) is a trademark of World Precision Instruments, Inc.

  1. CO2 Absorption Spectroscopy and Climate Change

    NASA Astrophysics Data System (ADS)

    Feldman, Daniel; Mlawer, Eli; Mlynczak, Martin; Gero, Jon; Collins, William; Torn, Margaret

    2014-03-01

    Most of the absorption, and therefore radiative forcing, due to increased atmospheric CO2 occurs in line wings, so utilizing an accurate line shape is necessary for climate science. Recent advances in CO2 absorption spectroscopy have been incorporated into benchmark line-by-line radiative transfer models. These updates include the Energy Corrected Sudden Approximation to represent isolated line profiles, line mixing, and line clusters. The CO2 line profiles are sub-Lorentzian and are explicitly modeled up to 25 cm-1 from each line's center. Consistent continuum absorption is implemented over the remainder of the profile except for modest empirical adjustments based on observations. Thus, line-by-line models calculate the absorption effects of CO2 that agree with theory and measurements. This is validated with long-term spectroscopic measurements from the ARM program's AERI instrument. This spectroscopy trains computationally-efficient correlated-k methods for climate model radiative transfer, but they overpredict instantaneous radiative forcing from doubled CO2 by approximately 7% in part because they have larger errors handling the impact of increased CO2 in the stratosphere than the troposphere. The implications of this can be tested with supercomputers. This work was supported by the Director, Office of Science, Office of Biol. & Env. Res., Clim. & Env. Sci. Div., of the U.S. D.O.E., Contract No. DE-AC02-05CH11231 as part of the Atmos. Sys. Res.

  2. How Van der Waals Interactions Influence the Absorption Spectra of Pheophorbide a Complexes: A Mixed Quantum-Classical Study.

    PubMed

    Megow, Jörg

    2015-10-01

    The computation of dispersive site energy shifts due to van der Waals interaction (London dispersion forces) was combined with mixed quantum-classical methodology to calculate the linear optical absorption spectra of large pheophorbide a (Pheo) dendrimers. The computed spectra agreed very well with the measurements considering three characteristic optical features occurring with increasing aggregate size: a strong line broadening, a redshift, and a low-energy shoulder. The improved mixed quantum-classical methodology is considered a powerful tool in investigating molecular aggregates. PMID:26275373

  3. Absorption, fluorescence and second harmonic generation in Cr³⁺-doped BiB₃O₆ glasses.

    PubMed

    Kuznik, W; Fuks-Janczarek, I; Wojciechowski, A; Kityk, I V; Kiisk, V; Majchrowski, A; Jaroszewicz, L R; Brik, M G; Nagy, G U L

    2015-06-15

    Synthesis, spectral properties and photoinduced nonlinear optical effects of chromium-doped BiB3O6 glass are studied in the present paper. Absorption, excitation and time resolved luminescence spectra are presented and luminescence decay behavior is discussed. Detailed analysis of the obtained spectra (assignment of the most prominent spectral features in terms of the corresponding Cr(3+) energy levels, crystal field strength Dq, Racah parameters B and C) was performed. A weak photostimulated second harmonic generation signal was found to increase drastically due to poling by proton implantation in the investigated sample. PMID:25795605

  4. Providers get their due.

    PubMed

    Morrissey, J

    1994-11-01

    Providers are getting their due, but only after employing computer software programs to help sort through the complex managed-care contracts they've negotiated. More and more accounting departments are relying on contract management systems to ensure accurate billing. PMID:10138187

  5. Paying Their Dues.

    ERIC Educational Resources Information Center

    Scalzo, Teresa

    1995-01-01

    Some colleges and universities have found that alumni prefer to have ownership of their alumni association, and such a membership program can raise revenues for the institution while providing a valuable communication tool. A strong dues program can work well with an annual giving campaign. A variety of membership structures is possible. Details…

  6. Percutaneous absorption in preterm infants.

    PubMed

    West, D P; Halket, J M; Harvey, D R; Hadgraft, J; Solomon, L M; Harper, J I

    1987-11-01

    The skin of preterm infants varies considerably in its level of maturity. To understand skin absorption in premature infants better, we report a technique for the assessment of percutaneous absorption at various gestational and postnatal ages using stable, isotope-labeled (13C6) benzoic acid. Our results indicate that in the preterm infant, this method detects enhanced skin absorption in the first postnatal days, which declines over three weeks to that expected of a full-term infant. This approach also indicates an inverse relationship between gestational age and skin absorption, as well as postnatal age and skin absorption. The reported technique is a safe and noninvasive method using a model skin penetrant for the study of percutaneous absorption in preterm infants from which basic data may be derived to add to our understanding of skin barrier function. PMID:3422856

  7. Microwave absorptions of ultrathin conductive films and designs of frequency-independent ultrathin absorbers

    SciTech Connect

    Li, Sucheng; Anwar, Shahzad; Lu, Weixin; Hang, Zhi Hong; Hou, Bo E-mail: phyhoubo@gmail.com; Shen, Mingrong; Wang, Chin-Hua

    2014-01-15

    We study the absorption properties of ultrathin conductive films in the microwave regime, and find a moderate absorption effect which gives rise to maximal absorbance 50% if the sheet (square) resistance of the film meets an impedance matching condition. The maximal absorption exhibits a frequency-independent feature and takes place on an extremely subwavelength scale, the film thickness. As a realistic instance, ∼5 nm thick Au film is predicted to achieve the optimal absorption. In addition, a methodology based on metallic mesh structure is proposed to design the frequency-independent ultrathin absorbers. We perform a design of such absorbers with 50% absorption, which is verified by numerical simulations.

  8. Absorption of surface acoustic waves by topological insulator thin films

    SciTech Connect

    Li, L. L.; Xu, W.

    2014-08-11

    We present a theoretical study on the absorption of the surface acoustic waves (SAWs) by Dirac electrons in topological insulator (TI) thin films (TITFs). We find that due to momentum and energy conservation laws, the absorption of the SAWs in TITFs can only be achieved via intra-band electronic transitions. The strong absorption can be observed up to sub-terahertz frequencies. With increasing temperature, the absorption intensity increases significantly and the cut-off frequency is blue-shifted. More interestingly, we find that the absorption of the SAWs by the TITFs can be markedly enhanced by the tunable subgap in the Dirac energy spectrum of the TI surface states. Such a subgap is absent in conventional two-dimensional electron gases (2DEGs) and in the gapless Dirac 2DEG such as graphene. This study is pertinent to the exploration of the acoustic properties of TIs and to potential application of TIs as tunable SAW devices working at hypersonic frequencies.

  9. Enhanced broadband absorption in gold by plasmonic tapered coaxial holes.

    PubMed

    Mo, Lei; Yang, Liu; Nadzeyka, Achim; Bauerdick, Sven; He, Sailing

    2014-12-29

    Gold absorbers based on plasmonic tapered coaxial holes (PTCHs) are demonstrated theoretically and experimentally. An average absorption of over 0.93 is obtained theoretically in a broad wavelength range from 300 nm to 900 nm without polarization sensitivity due to the structural symmetry. Strong scattering of the incident light by the tapered coaxial holes is the main reason for the high absorption in the short wavelength range below about 550 nm, while gap surface plasmon polaritons propagating along the taper dominate the resonance-induced high absorption in the long wavelength range. Combining two PTCHs with different structural parameters can further enhance the absorption and thus increase the spectral bandwidth, which is verified by a sample fabricated by focused ion beam milling. This design is promising to be extended to other metals to realize effective and efficient light harvesting and absorption. PMID:25607189

  10. Intrinsic nature of visible-light absorption in amorphous semiconducting oxides

    SciTech Connect

    Kang, Youngho; Song, Hochul; Han, Seungwu; Nahm, Ho-Hyun; Jeon, Sang Ho; Cho, Youngmi

    2014-03-01

    To enlighten microscopic origin of visible-light absorption in transparent amorphous semiconducting oxides, the intrinsic optical property of amorphous InGaZnO{sub 4} is investigated by considering dipole transitions within the quasiparticle band structure. In comparison with the crystalline InGaZnO{sub 4} with the optical gap of 3.6 eV, the amorphous InGaZnO{sub 4} has two distinct features developed in the band structure that contribute to significant visible-light absorption. First, the conduction bands are down-shifted by 0.55 eV mainly due to the undercoordinated In atoms, reducing the optical gap between extended states to 2.8 eV. Second, tail states formed by localized oxygen p orbitals are distributed over ∼0.5 eV near the valence edge, which give rise to substantial subgap absorption. The fundamental understanding on the optical property of amorphous semiconducting oxides based on underlying electronic structure will pave the way for resolving instability issues in recent display devices incorporating the semiconducting oxides.

  11. Polyethylene/silica nanocomposites: absorption current and the interpretation of SCLC

    NASA Astrophysics Data System (ADS)

    Lau, K. Y.; Vaughan, A. S.; Chen, G.; Hosier, I. L.; Ching, K. Y.; Quirke, N.

    2016-07-01

    The topic of nanodielectrics continues to receive significant attention from today’s dielectrics community, due to the property enhancements that can stem from the unique interfacial features within such material systems. Nevertheless, understanding the interfacial phenomena that occur in nanodielectrics, which determine their electrical behaviour, is challenging. In this paper, we report on an investigation into the absorption current behaviour of two nanocomposite systems, one containing an untreated nanosilica and the other containing the same nanofiller chemically modified using trimethoxy(propyl)silane. The results indicate that the absorption current behaviour of all the nanocomposites is very different from that of the reference, unfilled polymer; while the current flowing through the unfilled polyethylene decreased monotonically with time in a conventional manner, all the nanocomposites revealed an initial decrease followed by a period in which the current increased with increasing time of electric field application. Possible mechanisms leading to the observed absorption current behaviour in the nanocomposites are discussed with the aid of space charge measurements. The presence of space charge limited conduction (SCLC) and its trap-filled limit is proposed.

  12. Experimental issues on K- absorption by few nucleons and the search for Bound Kaonic Nuclear Systems

    NASA Astrophysics Data System (ADS)

    Filippi, A.

    2010-08-01

    The available experimental data on K- absorption on nuclei are rather old and scarce and cannot help very much to understand whether the formation of composite objects made by kaons and many nucleons can occur. The existence of such structures is suggested by a few theoretical models, but many others do not expect them—or at least consider their experimental observation very difficult. The experimental study of their existence is based on the observation of hyperon-nucleon correlations, and on the features of the Λp(d,t) invariant mass distributions. If existing, in fact, these aggregates should non-mesonically decay in hyperon-nucleons final states, being the pionic channels forbidden due to energy conservation. Complementary information may also be gathered by the study of missing mass distributions. Recent experiments restarted the study of K-A absorption in light nuclei, namely on 4He by KEK-E549, and on 6,7Li, 9Be and 12C by FINUDA at DAΦNE. The experimental results obtained so far by the various experiments studying the K- absorption in nuclei are here summarized and presented.

  13. Hydroxyl 1.563 Micron Absorption from Starspots on Active Stars

    NASA Astrophysics Data System (ADS)

    O'Neal, Douglas; Neff, James E.; Saar, Steven H.; Mines, Jonathan K.

    2001-10-01

    We present results from a study of starspots on active stars using a pair of vibrational-rotational absorption lines of the OH molecule near 1.563 μm. We detect excess OH absorption due to dark, cool starspots on several active stars of the RS CVn and BY Dra classes. Our results for the single-lined spectroscopic binaries II Pegasi, V1762 Cygni, and λ Andromedae augment those from a previous study that used a less sensitive detector. In this study, we were able for the first time to use molecular absorption features to measure starspot properties on double-lined spectroscopic binaries. Measuring the equivalent widths of these OH lines in inactive giant and dwarf stars of spectral types G, K, and M, we find that the total equivalent width of the line pair increases approximately linearly as effective temperature decreases from 5000 to 3000 K. We measure starspot filling factors by fitting the spectra of active stars with linear combinations of comparison star spectra representing the spot and nonspot regions of the star.

  14. Narrowing of sub-Doppler saturated-absorption resonances in multilayer gas cells

    NASA Astrophysics Data System (ADS)

    Izmailov, A. Ch.

    2014-07-01

    We have studied theoretically nontrivial specific features of sub-Doppler resonances of saturated absorption in a multilayer gas cell with a rarefied gas medium, which is a compact analog of a large number of plane-parallel atomic beams. Spatially separated saturating and probing monochromatic laser beams that co- and counterpropagate (at the same frequency) in this cell have been considered. In this situation, the action of the light radiation of the saturating beam on the probing beam is determined by optically pumped atoms that fly between the beams under conditions that the longitudinal components of their velocities experience selection due to a specific geometry of the multilayer cell. Such a selection leads to a narrowing of the sub-Doppler resonance in the absorption of the probing beam and decreases the difference between the structures of this resonance for the cases of co- and counterpropagation of the saturating radiation. We have found that, in the considered multilayer cell, the effective width of the sub-Doppler resonance can be smaller (by a factor of about 1.5) than the extremely narrow characteristic width of the well-known Lamb dip in spectroscopy of saturated absorption in the standard gas cell. Results of this study can be used in atomic spectroscopy of ultrahigh resolution and for the laser-frequency stabilization.

  15. Optical Absorption in Liquid Semiconductors

    NASA Astrophysics Data System (ADS)

    Bell, Florian Gene

    An infrared absorption cell has been developed which is suitable for high temperature liquids which have absorptions in the range .1-10('3) cm('-1). The cell is constructed by clamping a gasket between two flat optical windows. This unique design allows the use of any optical windows chemically compatible with the liquid. The long -wavelength limit of the measurements is therefore limited only by the choice of the optical windows. The thickness of the cell can easily be set during assembly, and can be varied from 50 (mu)m to .5 cm. Measurements of the optical absorption edge were performed on the liquid alloy Se(,1-x)Tl(,x) for x = 0, .001, .002, .003, .005, .007, and .009, from the melting point up to 475(DEGREES)C. The absorption was found to be exponential in the photon energy over the experimental range from 0.3 eV to 1.2 eV. The absorption increased linearly with concentration according to the empirical relation (alpha)(,T)(h(nu)) = (alpha)(,1) + (alpha)(,2)x, and the absorption (alpha)(,1) was interpreted as the absorption in the absence of T1. (alpha)(,1) also agreed with the measured absorption in 100% Se at corresponding temperatures and energies. The excess absorption defined by (DELTA)(alpha) = (alpha)(,T)(h(nu))-(alpha)(,1) was interpreted as the absorption associated with Tl and was found to be thermally activated with an activation energy E(,t) = 0.5 eV. The exponential edge is explained as absorption on atoms immersed in strong electric fields surrounding ions. The strong fields give rise to an absorption tail similar to the Franz-Keldysh effect. A simple calculation is performed which is based on the Dow-Redfield theory of absorption in an electric field with excitonic effects included. The excess absorption at low photon energies is proportional to the square of the concentration of ions, which are proposed to exist in the liquid according to the relation C(,i) (PROPORTIONAL) x(' 1/2)(.)e('-E)t('/kT), which is the origin of the thermal activation

  16. X-ray Absorption Spectroscopy

    SciTech Connect

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  17. Human due diligence.

    PubMed

    Harding, David; Rouse, Ted

    2007-04-01

    Most companies do a thorough job of financial due diligence when they acquire other companies. But all too often, deal makers simply ignore or underestimate the significance of people issues in mergers and acquisitions. The consequences are severe. Most obviously, there's a high degree of talent loss after a deal's announcement. To make matters worse, differences in decision-making styles lead to infighting; integration stalls; and productivity declines. The good news is that human due diligence can help companies avoid these problems. Done early enough, it helps acquirers decide whether to embrace or kill a deal and determine the price they are willing to pay. It also lays the groundwork for smooth integration. When acquirers have done their homework, they can uncover capability gaps, points of friction, and differences in decision making. Even more important, they can make the critical "people" decisions-who stays, who goes, who runs the combined business, what to do with the rank and file-at the time the deal is announced or shortly thereafter. Making such decisions within the first 30 days is critical to the success of a deal. Hostile situations clearly make things more difficult, but companies can and must still do a certain amount of human due diligence to reduce the inevitable fallout from the acquisition process and smooth the integration. This article details the steps involved in conducting human due diligence. The approach is structured around answering five basic questions: Who is the cultural acquirer? What kind of organization do you want? Will the two cultures mesh? Who are the people you most want to retain? And how will rank-and-file employees react to the deal? Unless an acquiring company has answered these questions to its satisfaction, the acquisition it is making will be very likely to end badly. PMID:17432159

  18. Gas in scattering media absorption spectroscopy - GASMAS

    NASA Astrophysics Data System (ADS)

    Svanberg, Sune

    2008-09-01

    An overview of the new field of Gas in Scattering Media Absorption Spectroscopy (GASMAS) is presented. GASMAS combines narrow-band diode-laser spectroscopy with diffuse media optical propagation. While solids and liquids have broad absorption features, free gas in pores and cavities in the material is characterized by sharp spectral signatures, typically 10,000 times sharper than those of the host material. Many applications in materials science, food packaging, pharmaceutics and medicine have been demonstrated. So far molecular oxygen and water vapour have been studied around 760 and 935 nm, respectively. Liquid water, an important constituent in many natural materials, such as tissue, has a low absorption at such wavelengths, allowing propagation. Polystyrene foam, wood, fruits, food-stuffs, pharmaceutical tablets, and human sinus cavities have been studied. Transport of gas in porous media can readily be studied by first immersing the material in, e.g., pure nitrogen, and then observing the rate at which normal air, containing oxygen, reinvades the material. The conductance of the sinus connective passages can be measured in this way by flushing the nasal cavity with nitrogen. Also other dynamic processes such as drying of materials can be studied. The techniques have also been extended to remote-sensing applications (LIDAR-GASMAS).

  19. A broadband absorption spectrometer using light emitting diodes for ultrasensitive, in situ trace gas detection

    SciTech Connect

    Langridge, Justin M.; Shillings, Alexander J. L.; Jones, Roderic L.; Ball, Stephen M.

    2008-12-15

    A broadband absorption spectrometer has been developed for highly sensitive and target-selective in situ trace gas measurements. The instrument employs two distinct modes of operation: (i) broadband cavity enhanced absorption spectroscopy (BBCEAS) is used to quantify the concentration of gases in sample mixtures from their characteristic absorption features, and (ii) periodic measurements of the cavity mirrors' reflectivity are made using step-scan phase shift cavity ringdown spectroscopy (PSCRDS). The latter PSCRDS method provides a stand-alone alternative to the more usual method of determining mirror reflectivities by measuring BBCEAS absorption spectra for calibration samples of known composition. Moreover, the instrument's two modes of operation use light from the same light emitting diode transmitted through the cavity in the same optical alignment, hence minimizing the potential for systematic errors between mirror reflectivity determinations and concentration measurements. The ability of the instrument to quantify absorber concentrations is tested in instrument intercomparison exercises for NO{sub 2} (versus a laser broadband cavity ringdown spectrometer) and for H{sub 2}O (versus a commercial hygrometer). A method is also proposed for calculating effective absorption cross sections for fitting the differential structure in BBCEAS spectra due to strong, narrow absorption lines that are under-resolved and hence exhibit non-Beer-Lambert law behavior at the resolution of the BBCEAS measurements. This approach is tested on BBCEAS spectra of water vapor's 4v+{delta} absorption bands around 650 nm. The most immediate analytical application of the present instrument is in quantifying the concentration of reactive trace gases in the ambient atmosphere. The instrument's detection limits for NO{sub 3} as a function of integration time are considered in detail using an Allan variance analysis. Experiments under laboratory conditions produce a 1{sigma} detection limit

  20. Absorption of ac fields in amorphous indium-oxide films

    NASA Astrophysics Data System (ADS)

    Ovadyahu, Z.

    2014-08-01

    Absorption data from applied ac fields in Anderson-localized amorphous indium-oxide (InxO) films are shown to be frequency and disorder dependent. The absorption shows a roll-off at a frequency which is much lower than the electron-electron scattering rate of the material when it is in the diffusive regime. This is interpreted as evidence for discreteness of the energy spectrum of the deeply localized regime. This is consistent with recent many-body localization scenarios. As the metal-insulator transition is approached, the absorption shifts to higher frequencies. Comparing with the previously obtained results on the crystalline version of indium-oxide (In2O3-x) implies a considerably higher inelastic electron-phonon scattering rate in the amorphous material. The range over which the absorption versus frequency decreases may indicate that a wide distribution of localization length is a common feature in these systems.

  1. Absorption of impinging water droplet in porous stones.

    PubMed

    Lee, J B; Radu, A I; Vontobel, P; Derome, D; Carmeliet, J

    2016-06-01

    This paper presents an experimental investigation and numerical analysis of the absorption of water droplets impacting porous stones. The absorption process of an impinging droplet is here fully characterized from spreading to evaporation in terms of absorbed mass during droplet depletion and moisture content distribution in a time-resolved manner for three different natural stones. High-speed imaging and neutron radiography are used to quantify moisture absorption in porous stones of varying moisture properties from deposition until depletion. During impact and spreading, the droplet exhibits a dynamic non-wetting behavior. At maximum spreading, the droplet undergoes pinning, resulting into the contact radius remaining constant until droplet depletion. Absorption undergoes two phases: initially, absorption is hindered due a contact resistance attributed to entrapped air; afterwards, a more perfect capillary contact occurs and absorption goes on until depletion, concurrently with evaporation and further redistribution. A finite-element numerical model for isothermal unsaturated moisture transport in porous media captures the phases of mass absorption in good agreement with the experimental data. Droplet spreading and absorption are highly determined by the impact velocity of the droplet, while moisture content redistribution after depletion is much less dependent on impact conditions. PMID:26975034

  2. Infrared Absorption Spectroscopy Measurement of SOx using Tunable Infrared Laser

    NASA Astrophysics Data System (ADS)

    Fukuchi, Tetsuo

    The absorption characteristics of sulfur dioxide (SO2) and sulfur trioxide (SO3) in the infrared region were measured using a quantum cascade laser and an absorption cell of length 1 m heated to 150°C. The laser was scanned over the wavelength range 6.9-7.4 μm, which included the absorption bands of SO2 and SO3. Measurement results showed that the absorption bands of SO2 and SO3 partially overlapped, with peaks at 7.28 μm and 7.35 μm for SO2 and 7.14 μm and 7.25 μm for SO3. These results showed the possbility of using infrared laser absorption spectroscopy for measurement of sulfur oxides (SOx) in flue gas. For SO3 measurement, infrared absorption spectroscopy was shown to be more suitable than ultraviolet absorption spectroscopy. The absorption characteristics of open air in the same wavelength region showed that the interference due to water vapor must be efficiently removed to perform SOx measurement in flue gas.

  3. Theory of strong-field attosecond transient absorption

    NASA Astrophysics Data System (ADS)

    Wu, Mengxi; Chen, Shaohao; Camp, Seth; Schafer, Kenneth J.; Gaarde, Mette B.

    2016-03-01

    Attosecond transient absorption is one of the promising new techniques being developed to exploit the availability of sub-femtosecond extreme ultraviolet (XUV) pulses to study the dynamics of the electron on its natural time scale. The temporal resolution in a transient absorption setup comes from the control of the relative delay and coherence between pump and probe pulses, while the spectral resolution comes from the characteristic width of the features that are being probed. In this review we focus on transient absorption scenarios where an attosecond pulse of XUV radiation creates a broadband excitation that is subsequently probed by a few cycle infrared (IR) laser. Because the attosecond XUV pulses are locked to the IR field cycle, the exchange of energy in the laser-matter interaction can be studied with unprecedented precision. We focus on the transient absorption by helium atoms of XUV radiation around the first ionization threshold, where we can simultaneoulsy solve the time-dependent Schrödinger equation for the single atom response and the Maxwell wave equation for the collective response of the nonlinear medium. We use a time-domain method that allows us to treat on an equal footing all the different linear and nonlinear processes by which the medium can exchange energy with the fields. We present several simple models, based on a few-level system interacting with a strong IR field, to explain many of the novel features found in attosecond transient absorption spectrograms. These include the presence of light-induced states, which demonstrate the ability to probe the dressed states of the atom. We also present a time-domain interpretation of the resonant pulse propagation features that appear in absorption spectra in dense, macroscopic media. We close by reviewing several recent experimental results that can be explained in terms of the models we discuss. Our aim is to present a road map for understanding future attosecond transient absorption

  4. Intestinal folate absorption

    PubMed Central

    Strum, Williamson; Nixon, Peter F.; Bertino, Joseph B.; Binder, Henry J.

    1971-01-01

    Intestinal absorption of the monoglutamate form of the principal dietary and circulating folate compound, 5-methyltetrahydrofolic acid (5-MTHF), was studied in the rat utilizing a synthetic highly purified radiolabeled diastereoisomer. Chromatography confirmed that the compound was not altered after transfer from the mucosa to the serosa. Accumulation against a concentration gradient was not observed in duodenal, jejunal, or ileal segments at 5-MTHF concentration from 0.5 to 500 nmoles/liter. Unidirectional transmural flux determination also did not indicate a significant net flux. Mucosal to serosal transfer of 5-MTHF was similar in all segments of the intestine and increased in a linear fashion with increased initial mucosal concentrations. Further, no alteration in 5-MTHF transfer was found when studied in the presence of metabolic inhibitors or folate compounds. These results indicate that 5-MTHF is not absorbed by the rat small intestine by a carrier-mediated system and suggest that 5-MTHF transfer most likely represents diffusion. Images PMID:5564397

  5. The coupled effect of fiber volume fraction and void fraction on hydraulic fluid absorption of quartz/BMI laminates

    NASA Astrophysics Data System (ADS)

    Hurdelbrink, Keith R.; Anderson, Jacob P.; Siddique, Zahed; Altan, M. Cengiz

    2016-03-01

    Bismaleimide (BMI) resin with quartz (AQ581) fiber reinforcement is a composite material frequently used in aerospace applications, such as engine cowlings and radomes. Various composite components used in aircrafts are exposed to different types of hydraulic fluids, which may lead to anomalous absorption behavior over the service life of the composite. Accurate predictive models for absorption of liquid penetrants are particularly important as the composite components are often exposed to long-term degradation due to absorbed moisture, hydraulic fluids, or similar liquid penetrants. Microstructural features such as fiber volume fraction and void fraction can have a significant effect on the absorption behavior of fiber-reinforced composites. In this paper, hydraulic fluid absorption characteristics of quartz/BMI laminates fabricated from prepregs preconditioned at different relative humidity and subsequently cured at different pressures are presented. The composite samples are immersed into hydraulic fluid at room temperature, and were not subjected to any prior degradation. To generate process-induced microvoids, prepregs were conditioned in an environmental chamber at 2% or 99% relative humidity at room temperature for a period of 24 hours prior to laminate fabrication. To alter the fiber volume fraction, the laminates were fabricated at cure pressures of 68.9 kPa (10 psi) or 482.6 kPa (70 psi) via a hot-press. The laminates are shown to have different levels of microvoids and fiber volume fractions, which were observed to affect the absorption dynamics considerably and exhibited clear non-Fickian behavior. A one-dimensional hindered diffusion model (HDM) was shown to be successful in predicting the hydraulic fluid absorption. Model prediction indicates that as the fabrication pressure increased from 68.9 kPa to 482.6 kPa, the maximum fluid content (M∞) decreased from 8.0% wt. to 1.0% wt. The degree of non-Fickian behavior, measured by hindrance coefficient (

  6. Modeling the Oxygen K Absorption in the Interstellar Medium: An XMM-Newton View of Sco X-1

    NASA Technical Reports Server (NTRS)

    Garcia, J.; Ramirez, J. M.; Kallman, T. R.; Witthoeft, M.; Bautista, M. A.; Mendoza, C.; Palmeri, P.; Quinet, P.

    2011-01-01

    We investigate the absorption structure of the oxygen in the interstellar medium by analyzing XMM-Newton observations of the low mass X-ray binary Sco X-1. We use simple models based on the O I atomic cross section from different sources to fit the data and evaluate the impact of the atomic data in the interpretation of astrophysical observations. We show that relatively small differences in the atomic calculations can yield spurious results. We also show that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21 - 24.5 Angstrom wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of Epsilon = 10(exp -4) erg/sq cm, and an oxygen column density of N(sub O) approx. = 8-10 x 10(exp 17)/sq cm. Our models are able to reproduce both the K edge and the K(alpha) absorption line from O I, which are the two main features in this region. We find no conclusive evidence for absorption by other than atomic oxygen.

  7. Modeling the Oxygen K Absorption in the Interstellar Medium: An XMM-Newton View of Sco X-1

    NASA Astrophysics Data System (ADS)

    García, J.; Ramírez, J. M.; Kallman, T. R.; Witthoeft, M.; Bautista, M. A.; Mendoza, C.; Palmeri, P.; Quinet, P.

    2011-04-01

    We investigate the X-ray absorption structure of oxygen in the interstellar medium by analyzing XMM - Newton observations of the low-mass X-ray binary Sco X-1. Simple models based on the O I atomic photoabsorption cross section from different sources are used to fit the data and evaluate the impact of the atomic data on the interpretation of the observations. We show that relatively small differences in the atomic calculations can yield spurious results, and that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21.0-24.5 Å wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of ξ = 10-4 erg cm s-1 and an oxygen column density of N O ≈ (8-10) × 1017 cm-2. The models are able to reproduce both the K edge and the Kα absorption line from O I which are the two main features in this region. We find no conclusive evidence for absorption by anything other than atomic oxygen.

  8. MODELING THE OXYGEN K ABSORPTION IN THE INTERSTELLAR MEDIUM: AN XMM-NEWTON VIEW OF Sco X-1

    SciTech Connect

    GarcIa, J.; Bautista, M. A.; RamIrez, J. M.; Kallman, T. R.; Witthoeft, M.; Mendoza, C.; Palmeri, P.; Quinet, P. E-mail: manuel.bautista@wmich.edu E-mail: michael.c.witthoeft@nasa.gov E-mail: claudio@ivic.gob.v E-mail: quinet@umh.ac.be

    2011-04-10

    We investigate the X-ray absorption structure of oxygen in the interstellar medium by analyzing XMM - Newton observations of the low-mass X-ray binary Sco X-1. Simple models based on the O I atomic photoabsorption cross section from different sources are used to fit the data and evaluate the impact of the atomic data on the interpretation of the observations. We show that relatively small differences in the atomic calculations can yield spurious results, and that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21.0-24.5 A wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of {xi} = 10{sup -4} erg cm s{sup -1} and an oxygen column density of N{sub O} {approx} (8-10) x 10{sup 17} cm{sup -2}. The models are able to reproduce both the K edge and the K{alpha} absorption line from O I which are the two main features in this region. We find no conclusive evidence for absorption by anything other than atomic oxygen.

  9. Collaborative Writing Features

    ERIC Educational Resources Information Center

    Yong Mei Fung

    2010-01-01

    As part of a research study on collaborative writing, this paper discusses defining and facilitating features that occur during face-to-face collaboration, based on the literature and research. The defining features are mutual interaction, negotiations, conflict, and shared expertise. Facilitating features include affective factors, use of L1,…

  10. Quantitative materials analysis of micro devices using absorption-based thickness measurements

    NASA Astrophysics Data System (ADS)

    Sim, L. M.; Wog, B. S.; Spowage, A. C.

    2006-01-01

    Preliminary work in designing an X-ray inspection machine with the capability of providing quantitative thickness analysis based on absorption measurements has been demonstrated. This study attempts to use the gray levels data to investigate the nature and thickness of occluded features and materials within devices. The investigation focused on metallic materials essential to semiconductor and MEMS technologies such as tin, aluminium, copper, silver, iron and zinc. The materials were arranged to simulate different feature thicknesses and sample geometries. The X-ray parameters were varied in-order to modify the X-ray energy spectrum with the aim of optimising the measurement conditions for each sample. The capability of the method to resolve differences in thicknesses was found to be highly dependent on the material. The thickness resolution with aluminium was the poorest due to its low radiographic density. The thickness resolutions achievable for silver and tin were significantly better and of the order of 0.015 mm and 0.025 mm respectively. From the linear relationship between the X-ray attenuation and sample thickness established, the energy dependent linear attenuation coefficient for each material was determined for a series of specific energy spectra. A decrease in the linear attenuation coefficient was observed as the applied voltage and thickness of the material increased. The results provide a platform for the development of a novel absorption-based thickness measurement system that can be optimised for a range of industrial applications.

  11. Neutron absorption detector

    DOEpatents

    Bell, Zane William; Boatner, Lynn Allen

    2011-05-31

    A method of detecting an activator, the method including impinging a receptor material that is not predominately water and lacks a photoluminescent material with an activator and generating Cherenkov effect light due to the activator impinging the receptor material. The method further including identifying a characteristic of the activator based on the light.

  12. Solar Absorption in Cloudy Atmospheres

    NASA Technical Reports Server (NTRS)

    Harshvardhan; Ridgway, William; Ramaswamy, V.; Freidenreich, S. M.; Batey, Michael

    1996-01-01

    The theoretical computations used to compute spectral absorption of solar radiation are discussed. Radiative properties relevant to the cloud absorption problem are presented and placed in the context of radiative forcing. Implications for future measuring programs and the effect of horizontal inhomogeneities are discussed.

  13. Atlas of Infrared Absorption Lines

    NASA Technical Reports Server (NTRS)

    Park, J. H.

    1977-01-01

    This atlas of infrared absorption line contains absorption line parameters (line strength vs. wavenumber) from 500 to 7000 cm(exp-1) for 15 gases: H2O, CO2, O3, N2O, CO, CH4, O2, SO2, NO, NO2, NH3, HCl, HF, HNO3 and CH3Cl.

  14. Hot tube atomic absorption spectrochemistry.

    PubMed

    Woodriff, R; Stone, R W

    1968-07-01

    A small, commercially available atomic absorption instrument is used with a heated graphite tube for the atomic absorption analysis of liquid and solid silver samples. Operating conditions of the furnace are described and a sensitivity of about 5 ng of silver is reported. PMID:20068797

  15. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  16. Atmospheric absorption of sound - Update

    NASA Technical Reports Server (NTRS)

    Bass, H. E.; Sutherland, L. C.; Zuckerwar, A. J.

    1990-01-01

    Best current expressions for the vibrational relaxation times of oxygen and nitrogen in the atmosphere are used to compute total absorption. The resulting graphs of total absorption as a function of frequency for different humidities should be used in lieu of the graph published earlier by Evans et al (1972).

  17. The Far-Infrared Absorption Spectrum of Low Temperature Hydrogen Gas.

    NASA Astrophysics Data System (ADS)

    Wishnow, Edward Hyman

    contribute to the translational continuum, no sharp spectral features are observed that can be attributed to dimer transitions. These low temperature, low pressure spectra are the first experimental searches for dimer structure across the translational band. The H_2^ectra show the sharp R(0) line of HD superposed on the translational band at 89.2 cm^{-1}, where the HD is present in the gas in natural abundance. The electric dipole moment of HD has been measured from the intensity of this line and it equals (0.81 +/- 0.05)times10^{-3} debye. The low temperature H_2^ectra provide an experimental test of the theory of collision -induced absorption and the model of the H_2 intermolecular potential. Furthermore, since the present experimental conditions are close to those found in the atmospheres of the planets Uranus and Neptune, these spectra also have relevance to astronomical observations of H_2. This work demonstrates, in particular, the feasibility of using measurements of the HD R(0) line and the underlying H_2 translational band to obtain planetary D/H ratios. In addition to hydrogen, spectra of H _2-He mixtures, D_2, N_2, O_2; and mixtures of N_2, CH _4, and CO with Ar, have been obtained at 78 and 88 K over the spectral region 20-180 cm ^{-1}. The N_2 and N_2-Ar spectra exhibit structure superposed on the collision-induced translational-rotational band; this structure has not been previously observed and it is probably due to dimer transitions.

  18. ALPHA ATTENUATION DUE TO DUST LOADING

    SciTech Connect

    Dailey, A; Dennis Hadlock, D

    2007-08-09

    Previous studies had been done in order to show the attenuation of alpha particles in filter media. These studies provided an accurate correction for this attenuation, but there had not yet been a study with sufficient results to properly correct for attenuation due to dust loading on the filters. At the Savannah River Site, filter samples are corrected for attenuation due to dust loading at 20%. Depending on the facility the filter comes from and the duration of the sampling period, the proper correction factor may vary. The objective of this study was to determine self-absorption curves for each of three counting instruments. Prior work indicated significant decreases in alpha count rate (as much as 38%) due to dust loading, especially on filters from facilities where sampling takes place over long intervals. The alpha count rate decreased because of a decrease in the energy of the alpha. The study performed resulted in a set of alpha absorption curves for each of three detectors. This study also took into account the affects of the geometry differences in the different counting equipment used.

  19. Optical absorption of silicon nanowires

    SciTech Connect

    Xu, T.; Lambert, Y.; Krzeminski, C.; Grandidier, B.; Stievenard, D.; Leveque, G.; Akjouj, A.; Pennec, Y.; Djafari-Rouhani, B.

    2012-08-01

    We report on simulations and measurements of the optical absorption of silicon nanowires (NWs) versus their diameter. We first address the simulation of the optical absorption based on two different theoretical methods: the first one, based on the Green function formalism, is useful to calculate the scattering and absorption properties of a single or a finite set of NWs. The second one, based on the finite difference time domain (FDTD) method, is well-adapted to deal with a periodic set of NWs. In both cases, an increase of the onset energy for the absorption is found with increasing diameter. Such effect is experimentally illustrated, when photoconductivity measurements are performed on single tapered Si nanowires connected between a set of several electrodes. An increase of the nanowire diameter reveals a spectral shift of the photocurrent intensity peak towards lower photon energies that allow to tune the absorption onset from the ultraviolet radiations to the visible light spectrum.

  20. Ultraviolet absorption spectrum of HOCl

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.

    1993-01-01

    The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 +/- 0.3) x 10 exp -19/sq cm (2 sigma error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988). An HOCl nu2 infrared band intensity of 230 +/- 35/sq cm atm was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.

  1. Observations of the interstellar ice grain feature in the Taurus molecular clouds

    SciTech Connect

    Whittet, D.C.B.; Bode, H.F.; Longmore, A.J.; Baines, D.W.T.; Evans, A.

    1983-01-01

    Although water ice was originally proposed as a major constituent of the interstellar grain population (e.g. Oort and van de Hulst, 1946), the advent of infrared astronomy has shown that the expected absorption due to O-H stretching vibrations at 3 ..mu..m is illusive. Observations have in fact revealed that the carrier of this feature is apparently restricted to regions deep within dense molecular clouds (Merrill et al., 1976; Willner et al., 1982). However, the exact carrier of this feature is still controversial, and many questions remain as to the conditions required for its appearance. It is also uncertain whether it is restricted to circumstellar shells, rather than the general cloud medium. Detailed discussion of the 3 ..mu..m band properties is given elsewhere in this volume. 15 references, 4 figures.

  2. Effect of UV Absorption on Fabrication of Fiber-Optic Bragg Gratings

    NASA Technical Reports Server (NTRS)

    Wang, Ying; Sharma, Anup; Burdine, Robert (Technical Monitor)

    2000-01-01

    UV light is used to fabricate fiber-optic gratings also heats up the fiber due to absorption by either the fiber-buffer, fiber-cladding, doped with titania or a thin coating of paint. Significant enhancement in the rate of grating fabrication is observed due to UV light absorption.

  3. Studies of galaxies giving rise to QSO absorption systems and observations of the high-redshift universe

    NASA Astrophysics Data System (ADS)

    Chen, Hsiao-Wen

    I present a study of the galaxies that give rise to Lyman-α (Lyα) and triply ionized carbon (CIV) absorption lines observed in the spectra of background quasi-stellar objects (QSOs), as well as on studies of the high-redshift universe. By comparing the redshifts of galaxies and Lyα absorption systems along common lines of sight, I confirmed the existence of an anti- correlation between Lyα absorption equivalent width and galaxy impact parameter. Further analysis showed that tenuous gas is likely to be distributed around galaxies in spherical halos rather than in flattened disks with the gaseous extent scaling with galaxy B-band and K-band luminosities. I found that extended gaseous halos are a common and generic feature of galaxies over a wide range of luminosity and morphological type and Lyα absorption systems traced a significant and representative portion of the galaxy population. Applying the scaling relation between galaxy gaseous radius and galaxy B-band luminosity to predict the incidence of Lyα absorption systems originating in extended gaseous envelopes of galaxies, I found that luminous galaxies can explain about 50% of Lyα absorption systems with absorption equivalent width W > 0.3 Å. By comparing the redshifts of galaxies and CIV absorption systems along common lines of sight, I found that extended gaseous halos of galaxies have been metal contaminated out to large galactocentric radii, ~100 h-1 kpc. The covering factor of ionized gas in galactic halos was estimated to be 0.93 with a 1 σ lower bound of 0.83, which may strongly constrain the possibilities that CIV absorption systems arised in accreting satellite galaxies or in filaments of gravitationally collapsed structures. To study the high-redshift universe, I analyzed very deep slitless spectroscopy observations acquired by the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. These observations are especially suited for identifying very distant galaxies due to

  4. Gas-absorption process

    DOEpatents

    Stephenson, Michael J.; Eby, Robert S.

    1978-01-01

    This invention is an improved gas-absorption process for the recovery of a desired component from a feed-gas mixture containing the same. In the preferred form of the invention, the process operations are conducted in a closed-loop system including a gas-liquid contacting column having upper, intermediate, and lower contacting zones. A liquid absorbent for the desired component is circulated through the loop, being passed downwardly through the column, regenerated, withdrawn from a reboiler, and then recycled to the column. A novel technique is employed to concentrate the desired component in a narrow section of the intermediate zone. This technique comprises maintaining the temperature of the liquid-phase input to the intermediate zone at a sufficiently lower value than that of the gas-phase input to the zone to effect condensation of a major part of the absorbent-vapor upflow to the section. This establishes a steep temperature gradient in the section. The stripping factors below this section are selected to ensure that virtually all of the gases in the downflowing absorbent from the section are desorbed. The stripping factors above the section are selected to ensure re-dissolution of the desired component but not the less-soluble diluent gases. As a result, a peak concentration of the desired component is established in the section, and gas rich in that component can be withdrawn therefrom. The new process provides important advantages. The chief advantage is that the process operations can be conducted in a single column in which the contacting zones operate at essentially the same pressure.

  5. Photosensitivity in sponge due to cytochrome c oxidase?

    PubMed

    Björn, Lars Olof; Rasmusson, Allan G

    2009-06-01

    An action spectrum for photosensitivity in sponge larvae published by Leys et al. [J. Comp. Physiol., A, 2002, 188, 199-202] was interpreted by the authors as being due to a combination of light absorption by flavin or carotenoid in the blue region, and another pigment such as pterin in the long-wavelength region. Here we show here that their action spectrum closely matches the absorption spectrum of reduced cytochrome c oxidase that is present in sponges, and compare with other photoreactions which are thought to be due to this chromoprotein. PMID:19492101

  6. Practical multi-featured perfect absorber utilizing high conductivity silicon

    NASA Astrophysics Data System (ADS)

    Gok, Abdullah; Yilmaz, Mehmet; Bıyıklı, Necmi; Topallı, Kağan; Okyay, Ali K.

    2016-03-01

    We designed all-silicon, multi-featured band-selective perfect absorbing surfaces based on CMOS compatible processes. The center wavelength of the band-selective absorber can be varied between 2 and 22 μm while a bandwidth as high as 2.5 μm is demonstrated. We used a silicon-on-insulator (SOI) wafer which consists of n-type silicon (Si) device layer, silicon dioxide (SiO2) as buried oxide layer, and n-type Si handle layer. The center wavelength and bandwidth can be tuned by adjusting the conductivity of the Si device and handle layers as well as the thicknesses of the device and buried oxide layers. We demonstrate proof-of-concept absorber surfaces experimentally. Such absorber surfaces are easy to microfabricate because the absorbers do not require elaborate microfabrication steps such as patterning. Due to the structural simplicity, low-cost fabrication, wide spectrum range of operation, and band properties of the perfect absorber, the proposed multi-featured perfect absorber surfaces are promising for many applications. These include sensing devices, surface enhanced infrared absorption applications, solar cells, meta-materials, frequency selective sensors and modulators.

  7. THE STANDARD CALIBRATION INSTRUMENT AUTOMATION SYSTEM FOR THE ATOMIC ABSORPTION SPECTROPHOTOMETER. PART III: PROGRAM DOCUMENTATION

    EPA Science Inventory

    This report contains complete documentation for the 15 programs and 11 data files of the EPA Atomic Absorption Instrument Automation System. The system incorporates the following major features: (1) multipoint calibration using first, second, or third degree regression or linear ...

  8. Interstellar Silicate Dust Grain Properties in Distant Galaxies Probed by Quasar Absorption Systems

    NASA Astrophysics Data System (ADS)

    Aller, Monique C.; Kulkarni, Varsha P.; York, Donald G.; Welty, Daniel E.; Vladilo, Giovanni; Som, Debopam

    2015-01-01

    Dust grains are a fundamental component of the interstellar medium, and significantly impact many of the physical processes driving galaxy evolution, including star formation, and the heating, cooling and ionization of interstellar material. Using the absorption features produced by dust in the spectra of luminous background quasars, it is possible to study the properties of extragalactic interstellar dust grains. We will present results from an ongoing program utilizing existing Spitzer Space Telescope infrared quasar spectra to probe silicate dust grain properties in z<1.4 quasar absorption systems. In combination with complementary ground-based data on associated gas-phase metal absorption lines, we explore connections between the interstellar dust and gas in the quasar absorption systems. Our project yields clear detections of the 10 micron silicate dust absorption feature in the studied systems, as well as detections of the 18 micron silicate dust absorption feature in sources with adequate spectral coverage. Based on measured variations in the breath, peak wavelength, and substructure of the 10 micron absorption features, there appear to be differences in the silicate dust grain properties from system-to-system. We also show indications of trends between the gas-phase metal properties, such as metallicity and gas velocity spread, with the silicate dust grain absorption properties. Support for this work is provided by NASA through an award issued by JPL/Caltech and through NASA grant NNX14AG74G, and from National Science Foundation grants AST-0908890 and AST-1108830 to the University of South Carolina.

  9. Size-dependent absorption and defect states in CdSe nanocrystals in various multilayer structures.

    PubMed

    Nesheva, D; Levi, Z; Aneva, Z; Zrinscak, I; Main, C; Reynolds, S

    2002-12-01

    GeS2-CdSe superlattices and composite films are prepared by consecutive thermal evaporation of CdSe and GeS2 in vacuum. CdSe layer thickness varies between 1 and 10 nm, while the thickness of GeS2 layers is either equal (in superlattices) to or 20 times greater (in composite films) than that of CdSe layers. Standard spectral photocurrent measurements and various constant photocurrent methods are used to study optical absorption of all samples. An overall blueshift is observed with decreasing CdSe layer thickness of superlattices. This shift is related to a size-induced increase of the optical band gap of CdSe due to one-dimensional carrier confinement in the continuous nanocrystalline CdSe layers. A number of features are observed in the absorption spectra of composite films containing CdSe nanocrystals with average radii of approximately 2.5 and approximately 3.3 nm. They are discussed in terms of three-dimensional carrier confinement and are considered a manifestation of excited electron states in CdSe nanocrystals embedded in GeS2 thin film matrix. In addition to these discrete features, the exponential dependence of the optical absorption (Urbach) edge indicates a distribution of "valence band" tail states associated with disorder. Transient photoconductivity measurements made on similarly prepared SiOx-CdSe superlattices exhibit a rapid fall in photocurrent by a power law decay over several orders of magnitude of time, which is consistent with multi-pletrapping transport via an extensive distribution of deep defects. PMID:12908429

  10. Adaptive feature extraction expert

    SciTech Connect

    Yuschik, M.

    1983-01-01

    The identification of discriminatory features places an upper bound on the recognition rate of any automatic speech recognition (ASR) system. One way to structure the extraction of features is to construct an expert system which applies a set of rules to identify particular properties of the speech patterns. However, these patterns vary for an individual speaker and from speaker to speaker so that another expert is actually needed to learn the new variations. The author investigates the problem by using sets of discriminatory features that are suggested by a feature generation expert, improves the selectivity of these features with a training expert, and finally develops a minimally spanning feature set with a statistical selection expert. 12 references.

  11. Resonant Absorption of Bessel Beams

    NASA Astrophysics Data System (ADS)

    Fan, J.; Parra, E.; Milchberg, H. M.

    1999-11-01

    We report the first observation of enhanced laser-plasma optical absorption in a subcritical density plasma resulting from spatial resonances, here in the laser breakdown of a gas with a Bessel beam. The enhancement in absorption is directly correlated to enhancements both in confinement of laser radiation to the plasma and in its heating. Under certain conditions, azimuthal asymmetry in the laser beam is essential for efficient gas breakdown. Simulations of this absorption consistently explain the experimental observations. This work is supported by the National Science Foundation (PHY-9515509) and the US Department of Energy (DEF G0297 ER 41039).

  12. Absorption by dirty black holes: Null geodesics and scalar waves

    NASA Astrophysics Data System (ADS)

    Macedo, Caio F. B.; Leite, Luiz C. S.; Crispino, Luís C. B.

    2016-01-01

    Black holes are a paradigm in physics nowadays and are expected to be hosted at the centers of galaxies. Supermassive galactic black holes are not isolated, and their surroundings play crucial roles in many observational features. The absorption and scattering of fields by isolated black holes have been vastly studied, allowing the understanding of many phenomenological features. However, as far as we are aware, a study of the influence of the presence of matter surrounding black holes in their planar wave scattering and absorption spectrum is still lacking in the literature. This may be important in the analysis of, for instance, the accretion of dark matter by black holes. We consider planar massless scalar waves incident upon a Schwarzschild black hole surrounded by a thin spherical shell. We use the partial-wave method to determine the absorption cross section and present a selection of numerical results. In the low-frequency regime, we show that the absorption cross section is equal to the horizon area. At the high-frequency regime, we show that the absorption cross section approaches the geodesic capture cross section.

  13. Collision-induced absorption of O2 in the Herzberg continuum

    NASA Technical Reports Server (NTRS)

    SHARDANAND; Rao, A. D. P.

    1977-01-01

    Using a one meter normal incidence grating monochromator, the total absorption of radiation for O2 has been reinvestigated between 2000-2500 A. The absorption cross sections of O2 and O4 are then derived from total absorption measurements and compared with other available data. Additional measurements of O2 absorption have been made in the presence of Ar which does not absorb in this spectral region and is chemically inactive with O2. It is found that the absorption of oxygen increases in the presence of Ar, which is interpreted as due to the formation of O2-Ar dimers.

  14. Diode laser absorption sensors for combustion control

    NASA Astrophysics Data System (ADS)

    Xin, Zhou

    Combustion is the most widely used energy conversion technique in the world. Diode-laser absorption sensors offer significant opportunities and advantages for in situ measurements of multiple combustion parameters such as temperature and species concentration due to their high sensitivity, high spectral resolution, fast time response, robustness and non-intrusive character. The overall objective of this thesis is to design and develop time-resolved and real-time tunable diode laser sensors with the potential for combustion control. A crucial element in the design of a tunable-diode-laser optical-absorption-based sensor is the selection of optimum transitions. The strategy and spectroscopic criteria for selecting optimum wavelength regions and absorption line combinations are developed. The development of this design-rule approach establishes a new paradigm to optimize tunable diode laser sensors for target applications. The water vapor spectrum in the 1-2 mum near-infrared region is systematically analyzed to find the best absorption transition pairs for sensitive measurement of temperature in the target combustion environment using a single tunable diode laser. Two sensors are developed in this work. The first sensor is a 1.8 mum, single-laser temperature sensor based on direct absorption scans. Successful time-resolved measurements in a variety of laboratory and practical devices are presented and used to identify potential improvements, and design rules for a second-generation sensor are developed based on the lessons learned. The second generation sensor is a 1.4 mum, single-laser temperature sensor using water vapor absorption detected by wavelength-modulation spectroscopy (WMS), which facilitates rapid data analysis and a 2 kHz real-time data rate in the combustion experiments reported here. Demonstration experiments in a heated cell and a forced Hencken burner confirm the sensitivity and accuracy of the sensors. The first application of TDL thermometry to a

  15. Harnessing the electromagnetic absorptions of metamaterials for positive applications

    NASA Astrophysics Data System (ADS)

    Xiang, Yuanjiang; Zou, Yanhong; Luo, Hailu; Dai, Xiaoyu; Wen, Shuangchun; Fan, Dianyuan

    2010-08-01

    Absorption or loss is inevitable for the metal-based metamaterials (MMs) due to the intrinsic loss of the metal, and constitutes a major hurdle to the practical realization of most applications such as a sub-wavelength lens. Thus, to reduce the losses becomes one of the major challenges in the MM field. However, the inevitable loss can also be harnessed to take a positive role in the applications of MMs such as stealth technology or other types of cloaking devices. In this presentation, after a brief review of the advances in MMs-based absorbers, we present several schemes to fulfill the desired electromagnetic absorption properties, both linear and nonlinear. For linear absorption, we have experimentally demonstrated that the absorption performance of an ordinary microwave absorbing material can be evidently improved by using the electric resonance resulting from an array of subwavelength metallic circuit elements. For nonlinear absorption, we show theoretically that the active linear magnetic permeability induces a nonlinear absorption, similar to the two-photon absorption (TPA), of electric field in a lossy MM with a Kerr-type nonlinear polarization.

  16. Scramjet Performance Assessment Using Water Absorption Diagnostics (U)

    NASA Technical Reports Server (NTRS)

    Cavolowsky, John A.; Loomis, Mark P.; Deiwert, George

    1995-01-01

    Simultaneous multiple path measurements of temperature and H2O concentration will be presented for the AIMHYE test entries in the NASA Ames 16-Inch Shock Tunnel. Monitoring the progress of high temperature chemical reactions that define scramjet combustor efficiencies is a task uniquely suited to nonintrusive optical diagnostics. One application strategy to overcome the many challenges and limitations of nonintrusive measurements is to use laser absorption spectroscopy coupled with optical fibers. Absorption spectroscopic techniques with rapidly tunable lasers are capable of making simultaneous measurements of mole fraction, temperature, pressure, and velocity. The scramjet water absorption diagnostic was used to measure combustor efficiency and was compared to thrust measurements using a nozzle force balance and integrated nozzle pressures to develop a direct technique for evaluating integrated scramjet performance. Tests were initially performed with a diode laser tuning over a water absorption feature at 1391.7 nm. A second diode laser later became available at a wavelength near 1343.3 nm covering an additional water absorption feature and was incorporated in the system for a two-wavelength technique. Both temperature and mole fraction can be inferred from the lineshape analysis using this approach. Additional high temperature spectroscopy research was conducted to reduce uncertainties in the scramjet application. The lasers are optical fiber coupled to ports at the combustor exit and in the nozzle region. The output from the two diode lasers were combined in a single fiber, and the resultant two-wavelength beam was subsequently split into four legs. Each leg was directed through 60 meters of optical fiber to four combustor exit locations for measurement of beam intensity after absorption by the water within the flow. Absorption results will be compared to 1D combustor analysis using RJPA and nozzle CFD computations as well as to data from a nozzle metric

  17. A SURVEY OF ALKALI LINE ABSORPTION IN EXOPLANETARY ATMOSPHERES

    SciTech Connect

    Jensen, Adam G.; Redfield, Seth; Endl, Michael; Cochran, William D.; Koesterke, Lars; Barman, Travis S. E-mail: sredfield@wesleyan.edu E-mail: wdc@astro.as.utexas.edu E-mail: barman@lowell.edu

    2011-12-20

    We obtained over 90 hr of spectroscopic observations of four exoplanetary systems with the Hobby-Eberly Telescope. Observations were taken in transit and out of transit, and we analyzed the differenced spectra-i.e., the transmission spectra-to inspect it for absorption at the wavelengths of the neutral sodium (Na I) doublet at {lambda}{lambda}5889, 5895 and neutral potassium (K I) at {lambda}7698. We used the transmission spectrum at Ca I {lambda}6122-which shows strong stellar absorption but is not an alkali metal resonance line that we expect to show significant absorption in these atmospheres-as a control line to examine our measurements for systematic errors. We use an empirical Monte Carlo method to quantify these systematic errors. In a reanalysis of the same data set using a reduction and analysis pipeline that was derived independently, we confirm the previously seen Na I absorption in HD 189733b at a level of (- 5.26 {+-} 1.69) Multiplication-Sign 10{sup -4} (the average value over a 12 A integration band to be consistent with previous authors). Additionally, we tentatively confirm the Na I absorption seen in HD 209458b (independently by multiple authors) at a level of (- 2.63 {+-} 0.81) Multiplication-Sign 10{sup -4}, though the interpretation is less clear. Furthermore, we find Na I absorption of (- 3.16 {+-} 2.06) Multiplication-Sign 10{sup -4} at <3{sigma} in HD 149026b; features apparent in the transmission spectrum are consistent with real absorption and indicate this may be a good target for future observations to confirm. No other results (Na I in HD 147506b and Ca I and K I in all four targets) are significant to {>=}3{sigma}, although we observe some features that we argue are primarily artifacts.

  18. Encapsulation effects on carbonaceous aerosol light absorption

    SciTech Connect

    Sedlacek, A.J.; Onasch, T.; Davidovits, P.; Cross, E.; Mazzoleni, C.

    2010-03-15

    The contribution of aerosol absorption on direct radiative forcing is still an active area of research, in part, because aerosol extinction is dominated by light scattering and, in part, because the primary absorbing aerosol of interest, soot, exhibits complex aging behavior that alters its optical properties. The consequences of this can be evidenced by the work of Ramanathan and Carmichael (2008) who suggest that incorporating the atmospheric heating due to brown clouds (plumes containing soot byproducts from automobiles, biomass burning, wood-burning kitchen stoves, and coal-fired power plants) will increase black carbon (BC) radiative forcing from the Intergovernmental Panel on Climate Change best estimate of 0.34 Wm-2 (±0.25 Wm-2) (IPCC 2007) to 0.9 Wm-2. This noteworthy degree of uncertainty is due largely to the interdependence of BC optical properties on particle mixing state and aggregate morphology, each of which changes as the particle ages in the atmosphere and becomes encapsulated within a coating of inorganic and/or organic substances. In July 2008, a laboratory-based measurement campaign, led by Boston College and Aerodyne, was initiated to begin addressing this interdependence. To achieve insights into the interdependence of BC optical properties on particle mixing state and aggregate morphology, measurements of both the optical and physical properties of flame-generated soot under nascent, coated, and denuded conditions were conducted. This poster presents data on black carbon (BC) light absorption measured by Photothermal Interferometry (Sedlacek and Lee 2007). In addition to examining nascent BC—to provide a baseline measurement—encapsulation with varying thicknesses of either dioctyl sebacate (DOS) or sulfuric acid was conducted to glean insights into the interplay between particle mixing state and optical properties. Additionally, some experiments were carried out where BC was coated and then denuded. In the case of DOS-coated soot, a

  19. The rediscovery of absorption chillers

    SciTech Connect

    Katzel, J.

    1992-04-23

    Absorption chillers are back - and for two very good reasons: they are environmentally sound and, in many cases, economically attractive. One factor fueling this resurgence is the outlook for natural gas, the energy source of most absorption systems. Deregulation has spurred exploration, and forecasts indicate an abundant supply and relatively low prices through 2050. Threats of global warming and depletion of the ozone layer also are forces driving the absorption chiller market. Being a good corporate citizen today means minimizing or eliminating the use of chlorofluorocarbons (CFCs), the basis of many refrigerants used in mechanical chillers. Even as chemical and chiller manufacturers alike work to develop substitute refrigerants, the perfect alternative has yet to be found. Absorption units are free of these problems, a benefit that appeals to many people.

  20. Spectroscopic features of cytochrome P450 reaction intermediates

    PubMed Central

    Luthra, Abhinav; Denisov, Ilia G.; Sligar, Stephen G.

    2010-01-01

    Preface Cytochromes P450 constitute a broad class of heme monooxygenase enzymes with more than 11,500 isozymes which have been identified in organisms from all biological kingdoms [1]. These enzymes are responsible for catalyzing dozens chemical oxidative transformations such as hydroxylation, epoxidation, N-demethylation, etc., with very broad range of substrates [2-3]. Historically these enzymes received their name from ‘pigment 450’ due to the unusual position of the Soret band in UV-Vis absorption spectra of the reduced CO-saturated state [4-5]. Despite detailed biochemical characterization of many isozymes, as well as later discoveries of other ‘P450-like heme enzymes’ such as nitric oxide synthase and chloroperoxidase, the phenomenological term ‘cytochrome P450’ is still commonly used as indicating an essential spectroscopic feature of the functionally active protein which is now known to be due to the presence of a thiolate ligand to the heme iron [6]. Heme proteins with an imidazole ligand such as myoglobin and hemoglobin as well as an inactive form of P450 are characterized by Soret maxima at 420 nm [7]. This historical perspective highlights the importance of spectroscopic methods for biochemical studies in general, and especially for heme enzymes, where the presence of the heme iron and porphyrin macrocycle provides rich variety of specific spectroscopic markers available for monitoring chemical transformations and transitions between active intermediates of catalytic cycle. PMID:21167809

  1. Differential optical absorption spectrometer for measurement of tropospheric pollutants

    NASA Astrophysics Data System (ADS)

    Evangelisti, F.; Baroncelli, A.; Bonasoni, P.; Giovanelli, G.; Ravegnani, F.

    1995-05-01

    Our institute has recently developed a differential optical absorption spectrometry system called the gas analyzer spectrometer correlating optical absorption differences (GASCOAD), which features as a detector a linear image sensor that uses an artificial light source for long-path tropospheric-pollution monitoring. The GASCOAD, its method of eliminating interference from background sky light, and subsequent spectral analysis are reported and discussed. The spectrometer was used from 7 to 22 February 1993 in Milan, a heavily polluted metropolitan area, to measure the concentrations of SO2, NO2, O3, and HNO2 averaged over a 1.7-km horizontal light path. The findings are reported and briefly discussed.

  2. Plasma absorption evidence via chirped pulse spectral transmission measurements

    SciTech Connect

    Jedrkiewicz, Ottavia; Minardi, Stefano; Couairon, Arnaud; Jukna, Vytautas; Selva, Marco; Di Trapani, Paolo

    2015-06-08

    This work aims at highlighting the plasma generation dynamics and absorption when a Bessel beam propagates in glass. We developed a simple diagnostics allowing us to retrieve clear indications of the formation of the plasma in the material, thanks to transmission measurements in the angular and wavelength domains. This technique featured by the use of a single chirped pulse having the role of pump and probe simultaneously leads to results showing the plasma nonlinear absorption effect on the trailing part of the pulse, thanks to the spectral-temporal correspondence in the measured signal, which is also confirmed by numerical simulations.

  3. Stratospheric infrared continuum absorptions observed by the ATMOS instrument

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Zander, R.; Namkung, J. S.; Farmer, C. B.; Norton, R. H.

    1989-01-01

    A quantitative analysis of infrared continuum absorption features observed in ATMOS/Spacelab 3 (1985) spectra of the lower stratosphere is reported. Continuous absorption produced primarily by the collision-induced fundamental vibration-rotation band of O2 and to a lesser extent by the superposition of H2O far line wings has been observed in the 1400 to 1800/cm interval below tangent heights of about 25 km. Continuum optical depths measured in microwindows nearly free of atmospheric line absorption are 0.78 + or - 0.06 times those calculated with the O2 absorption coefficients of Timofeyev and Tonkov (1978). Transmittance measurements in microwindows between 2395 and 2535/cm have been used to study continuous absorption from the collision induced fundamental vibration-rotation band of N2 and the far wings of strong CO2 lines. The measured transmittances have been analyzed to derive best fit absorption coefficients for the N2 pressure-induced band at lower stratospheric temperatures (about 210 K).

  4. Electromagnetically induced absorption in a three-resonator metasurface system

    PubMed Central

    Zhang, Xueqian; Xu, Ningning; Qu, Kenan; Tian, Zhen; Singh, Ranjan; Han, Jiaguang; Agarwal, Girish S.; Zhang, Weili

    2015-01-01

    Mimicking the quantum phenomena in metamaterials through coupled classical resonators has attracted enormous interest. Metamaterial analogs of electromagnetically induced transparency (EIT) enable promising applications in telecommunications, light storage, slow light and sensing. Although the EIT effect has been studied extensively in coupled metamaterial systems, excitation of electromagnetically induced absorption (EIA) through near-field coupling in these systems has only been sparsely explored. Here we present the observation of the EIA analog due to constructive interference in a vertically coupled three-resonator metamaterial system that consists of two bright and one dark resonator. The absorption resonance is one of the collective modes of the tripartite unit cell. Theoretical analysis shows that the absorption arises from a magnetic resonance induced by the near-field coupling of the three resonators within the unit cell. A classical analog of EIA opens up opportunities for designing novel photonic devices for narrow-band filtering, absorptive switching, optical modulation, and absorber applications. PMID:26023061

  5. Giant absorption of light by molecular vibrations on a chip

    PubMed Central

    Karabchevsky, A.; Kavokin, A. V.

    2016-01-01

    Vibrational overtone spectroscopy of molecules is a powerful tool for drawing information on molecular structure and dynamics. It relies on absorption of near infrared radiation (NIR) by molecular vibrations. Here we show the experimental evidence of giant enhancement of the absorption of light in solutions of organic molecules due to the switch from ballistic to diffusive propagation of light through a channel silicate glass waveguide. We also experimentally address a dynamics of absorption as a function of time of adsorption of the organic molecules on a waveguide. The observed enhancement in diffusion regime is by a factor of 300 in N-Methylaniline and by factor of 80 in Aniline compared to the expected values in the case of ballistic propagation of light in a waveguide. Our results underscore the importance of a guide surface modification and the disordered molecular nano-layer in enhancement of absorption by amines on engineered integrated system. PMID:26887658

  6. Electromagnetically induced absorption in a three-resonator metasurface system.

    PubMed

    Zhang, Xueqian; Xu, Ningning; Qu, Kenan; Tian, Zhen; Singh, Ranjan; Han, Jiaguang; Agarwal, Girish S; Zhang, Weili

    2015-01-01

    Mimicking the quantum phenomena in metamaterials through coupled classical resonators has attracted enormous interest. Metamaterial analogs of electromagnetically induced transparency (EIT) enable promising applications in telecommunications, light storage, slow light and sensing. Although the EIT effect has been studied extensively in coupled metamaterial systems, excitation of electromagnetically induced absorption (EIA) through near-field coupling in these systems has only been sparsely explored. Here we present the observation of the EIA analog due to constructive interference in a vertically coupled three-resonator metamaterial system that consists of two bright and one dark resonator. The absorption resonance is one of the collective modes of the tripartite unit cell. Theoretical analysis shows that the absorption arises from a magnetic resonance induced by the near-field coupling of the three resonators within the unit cell. A classical analog of EIA opens up opportunities for designing novel photonic devices for narrow-band filtering, absorptive switching, optical modulation, and absorber applications. PMID:26023061

  7. Giant absorption of light by molecular vibrations on a chip.

    PubMed

    Karabchevsky, A; Kavokin, A V

    2016-01-01

    Vibrational overtone spectroscopy of molecules is a powerful tool for drawing information on molecular structure and dynamics. It relies on absorption of near infrared radiation (NIR) by molecular vibrations. Here we show the experimental evidence of giant enhancement of the absorption of light in solutions of organic molecules due to the switch from ballistic to diffusive propagation of light through a channel silicate glass waveguide. We also experimentally address a dynamics of absorption as a function of time of adsorption of the organic molecules on a waveguide. The observed enhancement in diffusion regime is by a factor of 300 in N-Methylaniline and by factor of 80 in Aniline compared to the expected values in the case of ballistic propagation of light in a waveguide. Our results underscore the importance of a guide surface modification and the disordered molecular nano-layer in enhancement of absorption by amines on engineered integrated system. PMID:26887658

  8. Giant absorption of light by molecular vibrations on a chip

    NASA Astrophysics Data System (ADS)

    Karabchevsky, A.; Kavokin, A. V.

    2016-02-01

    Vibrational overtone spectroscopy of molecules is a powerful tool for drawing information on molecular structure and dynamics. It relies on absorption of near infrared radiation (NIR) by molecular vibrations. Here we show the experimental evidence of giant enhancement of the absorption of light in solutions of organic molecules due to the switch from ballistic to diffusive propagation of light through a channel silicate glass waveguide. We also experimentally address a dynamics of absorption as a function of time of adsorption of the organic molecules on a waveguide. The observed enhancement in diffusion regime is by a factor of 300 in N-Methylaniline and by factor of 80 in Aniline compared to the expected values in the case of ballistic propagation of light in a waveguide. Our results underscore the importance of a guide surface modification and the disordered molecular nano-layer in enhancement of absorption by amines on engineered integrated system.

  9. Surface plasmon enhanced absorption and suppressed transmission in periodic arrays of graphene ribbons

    NASA Astrophysics Data System (ADS)

    Nikitin, A. Yu.; Guinea, F.; Garcia-Vidal, F. J.; Martin-Moreno, L.

    2012-02-01

    Resonance diffraction in the periodic array of graphene microribbons is theoretically studied following a recent experiment [L. Ju , Nature Nanotech.1748-338710.1038/nnano.2011.146 6, 630 (2011)]. Systematic studies over a wide range of parameters are presented. It is shown that a much richer resonant picture would be observable for higher relaxation times of charge carriers: More resonances appear and transmission can be totally suppressed. The comparison with the absorption cross-section of a single ribbon shows that the resonant features of the periodic array are associated with leaky plasmonic modes. The longest-wavelength resonance provides the highest visibility of the transmission dip and has the strongest spectral shift and broadening with respect to the single-ribbon resonance, due to collective effects.

  10. [A novel hyperspectra absorption enhancing method based on morphological top-hat transformation].

    PubMed

    Li, Hui; Lin, Qi-zhong; Wang, Qin-jun; Liu, Qing-jie; Chen, Yu

    2010-09-01

    Hyperspectral characteristics analysis of ground features is the basis for applications of high-resolution imaging technology to ground target identification and ground features classification. Based on morphological multi-scale Top-Hat transformation, a novel spectral absorption enhancing algorithms was put forward, which enhanced spectral absorption features while maintaining shape features of the absorption peak bands. Eleven reflectance spectra of different mineral groups were chosen from the mineral spectral library of the United States Geological Survey (USGS), and we used a K-means clustering analysis on both the absorption-enhanced spectra and the original reflectance spectra. Results showed that, firstly, clustering groups of the absorption-enhanced spectra (AES) had better similarity within the same clustering group, and greater difference between different groups, furthermore, they were more consistent with the geological background of these minerals compared with clustering result of the original spectra (OS). Secondly, while all the original spectra were re-sampled to their ASTER spectra and the AES clustering result was displayed in the form of ASTER spectra of the minerals, we could easily describe both the representative spectral feature of each clustering group, and the typical spectral differences between every two groups. These fully demonstrate that the absorption-enhanced spectra have enhanced absorption features of the mineral spectra, and improved the separability of hyper-spectra. Accordingly, feature analysis based on absorption enhanced spectra can be used as reference for information extracting based on multi-spectral remote sensing image data, and it is a very useful method of hyperspectral analysis. PMID:21105412

  11. π-Extended "Earring" Porphyrins with Multiple Cavities and Near-Infrared Absorption.

    PubMed

    Rao, Yutao; Kim, Taeyeon; Park, Kyu Hyung; Peng, Fulei; Liu, Lei; Liu, Yunmei; Wen, Bin; Liu, Shubin; Kirk, Steven Robert; Wu, Licheng; Chen, Bo; Ma, Ming; Zhou, Mingbo; Yin, Bangshao; Zhang, Yuexing; Kim, Dongho; Song, Jianxin

    2016-05-23

    β,β-tripyrrin-bridged earring porphyrins were synthesized through Suzuki-Miyaura cross coupling reactions. These porphyrinoids have multiple cavities and can accommodate two or three metal ions per molecule. The structures of the porphyrins have been elucidated by x-ray diffraction analysis, and feature curved π planes. The electronic spectra of the porphyrins exhibit near-infrared (NIR) absorptions and metal insertion leads to red-shifted and intensified absorption features. Electrochemical analysis and transient absorption measurements indicated that the porphyrins exhibit effective electronic communication between their central and peripheral moieties. PMID:27038255

  12. Role of Spatial Chirp in High Harmonic Extreme Ultraviolet (XUV) Absorption Spectroscopy of Thin Films

    NASA Astrophysics Data System (ADS)

    Lin, Ming-Fu

    XUV light from high harmonic generation is an emerging new tool for studying ultrafast dynamics. Such sources have intrinsic ``spatial chirp'' that can cause significant periodic artifacts in absorption spectra of inhomogeneous samples. We show that a uniform thin-film morphology is required in order to obtain harmonic-structure free absorption spectra, especially for organometallic complexes that have strong non-resonant absorption features from the organic ligands. Demonstration of several static absorption spectra of different organometallic complexes and perovskite materials reveals elemental, oxidation state, and band structure specificity in agreement with theoretical results.

  13. The temperature dependence of collision-induced absorption by oxygen near 6 microns

    NASA Technical Reports Server (NTRS)

    Orlando, John J.; Tyndall, Geoffrey S.; Nickerson, Karen E.; Calvert, Jack G.

    1991-01-01

    Coefficients for oxygen absorption in the infrared induced by collisions with O2 and N2 are reported over the range 1400-1800/cm and 225-356 K. These coefficients are used to calculate the absorption for O2 in air as a function of temperature and wavenumber, and comparisons are made with previous determinations. In addition, structured absorption features superimposed on the broad collision-induced absorption band, which were observed at all temperatures studied, are interpreted in terms of the presence of (O2)2 and O2-N2 van der Waals molecules.

  14. Enhanced near-infrared absorption in graphene with multilayer metal-dielectric-metal nanostructure.

    PubMed

    Zhang, Lei; Tang, Linlong; Wei, Wei; Cheng, Xinlu; Wang, Wei; Zhang, Hong

    2016-09-01

    A multilayer metal-dielectric-metal nanostructure is proposed to enhance the absorption in graphene in a near-infrared region. The main feature of the structure is the generation of strong magnetic response within the dielectric spacer, which is directly related to absorption enhancement in graphene to over 22 times higher than that of free-standing monolayer graphene. We also show that absorption enhancement in graphene can be easily controlled by adjusting the geometry of the propose structure. The simple structural configuration and the flexible tunability in absorption enhancement are beneficial for practical fabrication and future applications in graphene-based active optoelectronic devices. PMID:27607608

  15. New spectral features of stratospheric trace gases

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Kosters, J. J.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.

    1990-01-01

    A new Michelson-type interferometer system operating in the infrared at very high resolution (0.002 to 0.003 wavenumber FWHM) was used to record numerous balloon-borne solar absorption spectra of the stratosphere, ground-based solar absorption spectra, and laboratory spectra of molecules of atmospheric interest. Results obtained are reported for several important stratospheric trace gases, HNO3, ClONO2, HO2NO2, NO2, and COF2, in the 8 to 12 micron spectral region. Many features of these gases were identified in the stratospheric spectra. Comparison of the spectra with line-by-line simulations shows previous spectral parameters are often inadequate. New analysis of high resolution laboratory and atmospheric spectra and improved theoretical calculations will be required for all bands. Preliminary versions of several sets of improved line parameters are presented.

  16. Tomographic laser absorption spectroscopy using Tikhonov regularization.

    PubMed

    Guha, Avishek; Schoegl, Ingmar

    2014-12-01

    The application of tunable diode laser absorption spectroscopy (TDLAS) to flames with nonhomogeneous temperature and concentration fields is an area where only few studies exist. Experimental work explores the performance of tomographic reconstructions of species concentration and temperature profiles from wavelength-modulated TDLAS measurements within the plume of an axisymmetric McKenna burner. Water vapor transitions at 1391.67 and 1442.67 nm are probed using calibration-free wavelength modulation spectroscopy with second harmonic detection (WMS-2f). A single collimated laser beam is swept parallel to the burner surface, where scans yield pairs of line-of-sight (LOS) data at multiple radial locations. Radial profiles of absorption data are reconstructed using Tikhonov regularized Abel inversion, which suppresses the amplification of experimental noise that is typically observed for reconstructions with high spatial resolution. Based on spectral data reconstructions, temperatures and mole fractions are calculated point-by-point. Here, a least-squares approach addresses difficulties due to modulation depths that cannot be universally optimized due to a nonuniform domain. Experimental results show successful reconstructions of temperature and mole fraction profiles based on two-transition, nonoptimally modulated WMS-2f and Tikhonov regularized Abel inversion, and thus validate the technique as a viable diagnostic tool for flame measurements. PMID:25607968

  17. New features in MEDM.

    SciTech Connect

    Evans, K., Jr.

    1999-04-13

    MEDM, which is derived from Motif Editor and Display Manager, is the primary graphical interface to the EPICS control system. This paper describes new features that have been added to MEDM in the last two years. These features include new editing capabilities, a PV Info dialog box, a means of specifying limits and precision, a new implementation of the Cartesian Plot, new features for several objects, new capability for the Related Display, help, a user-configurable Execute Menu, reconfigured start-up options, and availability for Windows 95/98/NT. Over one hundred bugs have been fixed, and the program is quite stable and in extensive use.

  18. Absorption band Q model for the Earth

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.; Given, J. W.

    1981-01-01

    Attenuation in solids and liquids, as measured by the quality factor Q, is typically frequency dependent. In seismology, however, Q is usually assumed to be independent of frequency. Body wave, surface wave, and normal mode data are used to place constraints on the frequency dependence of Q in the mantle. Specific features of the absorption band model are: low-Q in the seismic band at both the top and the base of the mantle, low-Q for long-period body waves in the outer core, an inner core Q sub s that increases with period, and low Q sub p/Q sub s at short periods in the middle mantle.

  19. Small quantum absorption refrigerator with reversed couplings.

    PubMed

    Silva, Ralph; Skrzypczyk, Paul; Brunner, Nicolas

    2015-07-01

    Small quantum absorption refrigerators have recently attracted renewed attention. Here we present a missing design of a two-qubit fridge, the main feature of which is that one of the two machine qubits is itself maintained at a temperature colder than the cold bath. This is achieved by "reversing" the couplings to the baths compared to previous designs, where only a transition is maintained cold. We characterize the working regime and the efficiency of the fridge. We demonstrate the soundness of the model by deriving and solving a master equation. Finally, we discuss the performance of the fridge, in particular the heat current extracted from the cold bath. We show that our model performs comparably to the standard three-level quantum fridge and thus appears appealing for possible implementations of nanoscale thermal machines. PMID:26274153

  20. Small quantum absorption refrigerator with reversed couplings

    NASA Astrophysics Data System (ADS)

    Silva, Ralph; Skrzypczyk, Paul; Brunner, Nicolas

    2015-07-01

    Small quantum absorption refrigerators have recently attracted renewed attention. Here we present a missing design of a two-qubit fridge, the main feature of which is that one of the two machine qubits is itself maintained at a temperature colder than the cold bath. This is achieved by "reversing" the couplings to the baths compared to previous designs, where only a transition is maintained cold. We characterize the working regime and the efficiency of the fridge. We demonstrate the soundness of the model by deriving and solving a master equation. Finally, we discuss the performance of the fridge, in particular the heat current extracted from the cold bath. We show that our model performs comparably to the standard three-level quantum fridge and thus appears appealing for possible implementations of nanoscale thermal machines.

  1. Absorption of different lead compounds

    PubMed Central

    Barltrop, D.; Meek, F.

    1975-01-01

    A rapid method for the determination of relative absorption of dietary lead by rats is described. The influence of age, weight and dose rate has been determined and using standard conditions the tissue lead content of blood, kidney and femur are significantly correlated with each other and are a function of ingested lead. Eight lead compounds were evaluated using this technique and the findings related to lead acetate as a reference compound. Of the inorganic preparations studied, lead carbonate (basic) and metallic lead showed a twelve-fold difference in absorption, with the remaining compounds giving intermediate values. The absorption of lead from four organic compounds was determined from diets containing 7·5% corn oil added to the standard diet. Lead tallate was absorbed to the same degree as lead acetate, but lesser absorptions resulted from lead octoate, naphthenate and alsynate. The addition of corn oil to a final concentration of 7·5% of the diet enhanced the absorption of lead acetate. PMID:1208290

  2. Volcanic features of Io

    USGS Publications Warehouse

    Carr, M.H.; Masursky, H.; Strom, R.G.; Terrile, R.J.

    1979-01-01

    Volcanic activity is apparently higher on Io than on any other body in the Solar System. Its volcanic landforms can be compared with features on Earth to indicate the type of volcanism present on Io. ?? 1979 Nature Publishing Group.

  3. Automated colon cancer detection using hybrid of novel geometric features and some traditional features.

    PubMed

    Rathore, Saima; Hussain, Mutawarra; Khan, Asifullah

    2015-10-01

    Automatic classification of colon into normal and malignant classes is complex due to numerous factors including similar colors in different biological constituents of histopathological imagery. Therefore, such techniques, which exploit the textural and geometric properties of constituents of colon tissues, are desired. In this paper, a novel feature extraction strategy that mathematically models the geometric characteristics of constituents of colon tissues is proposed. In this study, we also show that the hybrid feature space encompassing diverse knowledge about the tissues׳ characteristics is quite promising for classification of colon biopsy images. This paper thus presents a hybrid feature space based colon classification (HFS-CC) technique, which utilizes hybrid features for differentiating normal and malignant colon samples. The hybrid feature space is formed to provide the classifier different types of discriminative features such as features having rich information about geometric structure and image texture. Along with the proposed geometric features, a few conventional features such as morphological, texture, scale invariant feature transform (SIFT), and elliptic Fourier descriptors (EFDs) are also used to develop a hybrid feature set. The SIFT features are reduced using minimum redundancy and maximum relevancy (mRMR). Various kernels of support vector machines (SVM) are employed as classifiers, and their performance is analyzed on 174 colon biopsy images. The proposed geometric features have achieved an accuracy of 92.62%, thereby showing their effectiveness. Moreover, the proposed HFS-CC technique achieves 98.07% testing and 99.18% training accuracy. The better performance of HFS-CC is largely due to the discerning ability of the proposed geometric features and the developed hybrid feature space. PMID:25819060

  4. Absorption line CW EPR using an amplitude modulated longitudinal field.

    PubMed

    Fedin, Matvey; Gromov, Igor; Schweiger, Arthur

    2004-11-01

    In standard continuous wave electron paramagnetic resonance (CW-EPR) experiments, the first derivative of absorption lines is detected. This type of a line shape is caused by the magnetic field modulation and is usually an undesired feature, since the sensitivity of CW-EPR drastically decreases with increasing linewidth. A new approach is introduced, which allows for the measurement of absorption line EPR spectra in systems with broad inhomogeneous lines. The method makes use of multiple-photon transitions that are induced in spin systems when a transverse microwave and a longitudinal radio frequency field are simultaneously applied. The absorption lines are obtained by using amplitude modulation of the radio frequency field and slight saturation of the spectral lines. The basics of the new approach are discussed and experimental examples are given. PMID:15504685

  5. A method for normalization of X-ray absorption spectra

    SciTech Connect

    Weng, T.-C.; Waldo, G.S.; Penner-Hahn, J.E.

    2010-07-20

    Accurate normalization of X-ray absorption data is essential for quantitative analysis of near-edge features. A method, implemented as the program MBACK, to normalize X-ray absorption data to tabulated mass absorption coefficients is described. Comparison of conventional normalization methods with MBACK demonstrates that the new normalization method is not sensitive to the shape of the background function, thus allowing accurate comparison of data collected in transmission mode with data collected using fluorescence ion chambers or solid-state fluorescence detectors. The new method is shown to have better reliability and consistency and smaller errors than conventional normalization methods. The sensitivity of the new normalization method is illustrated by analysis of data collected during an equilibrium titration.

  6. Electron density compression and oscillating effects on laser energy absorption in overdense plasma targets.

    PubMed

    Ge, Z Y; Zhuo, H B; Yu, W; Yang, X H; Yu, T P; Li, X H; Zou, D B; Ma, Y Y; Yin, Y; Shao, F Q; Peng, X J

    2014-03-01

    An analytical model for energy absorption during the interaction of an ultrashort, ultraintense laser with an overdense plasma is proposed. Both the compression effect of the electron density profile and the oscillation of the electron plasma surface are self-consistently included, which exhibit significant influences on the laser energy absorption. Based on our model, the general scaling law of the compression effect depending on laser strength and initial density is derived, and the temporal variation of the laser absorption due to the boundary oscillating effect is presented. It is found that due to the oscillation of the electron plasma surface, the laser absorption rate will vibrate periodically at ω or 2ω frequency for the p-polarized and s-polarized laser, respectively. The effect of plasma collision on the laser absorption has also been investigated, which shows a considerable rise in absorption with increasing electron-ion collision frequency for both polarizations. PMID:24730955

  7. Features in Saturn's rings

    NASA Technical Reports Server (NTRS)

    Esposito, Larry W.; Harris, Craig C.; Simmons, Karen E.

    1987-01-01

    A systematic, uniform search of Voyage 2 photopolarimeter system (PSS) data set for all significant features of Saturn's rings is described. On August 25, 1981, the PSS observed the occultation of the star Delta Scorpii by the rings of Saturn, and the timing of the data taking was rapid enough that the spatial resolution in the radial direction in the ring plane was better than 100 m. Tabular information and figures for 216 significant features that were found are presented.

  8. Feature Characterization Library

    2006-08-03

    FCLib is a data analysis toolkit constructed to meet the needs of data discovery in large-scale, spatio-temporal data such as finite element simulation data. FCLib is a C library toolkit of building blocks that can be assembled into complex analyses. Important features of FCLib include the following: (1) Support of feature-based analysis, (2) minimization of low-oevel processing, (3) ease of use, and (4) applicable to the wide variety of science domains.

  9. Terbium chloride--aluminum chloride vapor system. I. Absorption and excitation spectra

    SciTech Connect

    Caird, J.A.; Carnall, W.T.; Hessler, J.P.; Williams, C.W.

    1981-01-15

    The absorption spectrum of the vapor complex formed at elevated temperatures between TbCl/sub 3/ and AlCl/sub 3/ has been measured in the region 20 000--50 000 cm/sup -1/. Oscillator strengths of f--f absorption bands below 37 000 cm/sup -1/ were determined. Strong absorption due to opposite parity 4f/sup 7/5d states was observed in the 37 000 to 50 000 cm/sup -1/ region with a peak molar absorptivity of approximately 500 l/mol cm. Significant additional absorption attributed to a molecular complex was also observed in this region. By measuring the excitation spectrum it was found that the molecular absorption does not appear to lead to fluorescence of the /sup 5/D/sub 4/ state. In contrast, absorption by the 4f/sup 7/5d states does result in strong /sup 5/D/sub 4/ fluorescence.

  10. Correlation of XANES features with the scintillation efficiencies of Ce doped alkaline earth lithium silicate glasses

    SciTech Connect

    Blanchard, D.L.; Sunberg, D.S.; Craig, R.A.; Bliss, M.; Weber, M.J.

    1994-11-01

    Cerium-activated, lithium-silicate glasses are widely used as thermal neutron detectors because of their versatility, robustness and low cost. The glasses convert the energy of the neutrons to visible light pulses that may be counted. This process, scintillation, is generally thought to be composed of three steps: ionization, energy transfer, and luminescence. If defects are present, they can trap the excitations, altering the scintillation output. These features have been discussed previously. The presence of magnesium in these glasses increases scintillation efficiency, but as previously observed the effect drops by a factor greater than 2.5 with substitution through the series of alkaline earths. Here, cerium activated glasses of composition 20Li{sub 2}O{center_dot}15MO{center_dot}64.4SiO{sub 2}{center_dot}0.6Ce{sub 3}O{sub 3} (where m is Mg, Ca, Sr, or Ba) exhibit scintillation efficiencies that vary by more than a factor of 2.5 with the alkaline earth. Previous work has suggested a correlation between the microstructure of these glasses and scintillation efficiency. Measurements of the Ce L{sub III} x-ray absorption edge in the Mg, Ca and Sr glasses display a feature near the absorption edge that is suggestive of the presence of Ce{sup 4+}. The area of this peak is, in fact, correlated with the scintillation efficiency of the glass. The amount of Ce{sup 4+} indicated by the intensity of this feature is, however, too high to be a permanent population. The authors suspect that the feature is a transient phenomenon related to creation of Ce{sup 4+} and trapped electrons due to photoionization by the x-ray beam.

  11. Photodetachment spectroscopy of fluorenone radical anions microsolvated with methanol: rationalizing the anomalous solvatochromic behavior due to hydrogen bonding.

    PubMed

    Maeyama, Toshihiko; Yagi, Izumi; Yoshida, Keiji; Fujii, Asuka; Mikami, Naohiko

    2015-04-23

    The attribution of the extraordinary blue shift for the intramolecular charge-transfer absorption band of fluorenone radical anion solvated in protic media was investigated by means of photodetachment spectroscopy of the gas-phase anions microsolvated with methanol, in conjunction with quantum chemical calculations based on density functional theory. Sequential shifts of the vertical detachment energy as a function of the cluster size are consistent with theoretical predictions, where up to two methanol molecules can directly attach to the carbonyl group. In the photodetachment excitation spectra as alternatives to the photoabsorption spectra, with increasing cluster size, a new absorption band grows in the higher-energy region, which coincides with the blue-shifted band in protic media. Spectral simulations using time-dependent density functional theory with the CAM-B3LYP functional reproduced the feature of the phenomenon. Analyses on the electronic configuration elucidated that the extraordinarily blue shifts originate from energy-level repulsion due to solvation-induced resonant coupling with another electronic state. The orbital transition for the counterpart state corresponds to the first absorption band of the neutral fluorenone molecule, which has small oscillator strength from the ground state. It was found that correction of long-range electron exchange correlation is important for the spectral simulation involving the electronic-state coupling. PMID:25825951

  12. Thermodynamic derivatives of infrared absorptance

    NASA Technical Reports Server (NTRS)

    Broersma, S.; Walls, W. L.

    1974-01-01

    Calculation of the concentration, pressure, and temperature dependence of the spectral absorptance of a vibrational absorption band. A smooth thermodynamic dependence was found for wavelength intervals where the average absorptance is less than 0.65. Individual rotational lines, whose parameters are often well known, were used as bases in the calculation of medium resolution spectra. Two modes of calculation were combined: well-separated rotational lines plus interaction terms, or strongly overlapping lines that were represented by a compound line of similar shape plus corrections. The 1.9- and 6.3-micron bands of H2O and the 4.3-micron band of CO2 were examined in detail and compared with experiment.

  13. Absorption properties of identical atoms

    SciTech Connect

    Sancho, Pedro

    2013-09-15

    Emission rates and other optical properties of multi-particle systems in collective and entangled states differ from those in product ones. We show the existence of similar effects in the absorption probabilities for (anti)symmetrized states of two identical atoms. The effects strongly depend on the overlapping between the atoms and differ for bosons and fermions. We propose a viable experimental verification of these ideas. -- Highlights: •The absorption rates of a pair of identical atoms in product and (anti)symmetrized states are different. •The modifications of the optical properties are essentially determined by the overlapping between the atoms. •The absorption properties differ, in some cases, for bosons and fermions.

  14. Sensitivity in forward modeled hyperspectral reflectance due to phytoplankton groups

    NASA Astrophysics Data System (ADS)

    Manzo, Ciro; Bassani, Cristiana; Pinardi, Monica; Giardino, Claudia; Bresciani, Mariano

    2016-04-01

    Phytoplankton is an integral part of the ecosystem, affecting trophic dynamics, nutrient cycling, habitat condition, and fisheries resources. The types of phytoplankton and their concentrations are used to describe the status of water and the processes inside of this. This study investigates bio-optical modeling of phytoplankton functional types (PFT) in terms of pigment composition demonstrating the capability of remote sensing to recognize freshwater phytoplankton. In particular, a sensitivity analysis of simulated hyperspectral water reflectance (with band setting of HICO, APEX, EnMAP, PRISMA and Sentinel-3) of productive eutrophic waters of Mantua lakes (Italy) environment is presented. The bio-optical model adopted for simulating the hyperspectral water reflectance takes into account the reflectance dependency on geometric conditions of light field, on inherent optical properties (backscattering and absorption coefficients) and on concentrations of water quality parameters (WQPs). The model works in the 400-750nm wavelength range, while the model parametrization is based on a comprehensive dataset of WQP concentrations and specific inherent optical properties of the study area, collected in field surveys carried out from May to September of 2011 and 2014. The following phytoplankton groups, with their specific absorption coefficients, a*Φi(λ), were used during the simulation: Chlorophyta, Cyanobacteria with phycocyanin, Cyanobacteria and Cryptophytes with phycoerythrin, Diatoms with carotenoids and mixed phytoplankton. The phytoplankton absorption coefficient aΦ(λ) is modelled by multiplying the weighted sum of the PFTs, Σpia*Φi(λ), with the chlorophyll-a concentration (Chl-a). To highlight the variability of water reflectance due to variation of phytoplankton pigments, the sensitivity analysis was performed by keeping constant the WQPs (i.e., Chl-a=80mg/l, total suspended matter=12.58g/l and yellow substances=0.27m-1). The sensitivity analysis was

  15. Diagnosing the accretion flow in ultraluminous X-ray sources using soft X-ray atomic features

    NASA Astrophysics Data System (ADS)

    Middleton, Matthew J.; Walton, Dominic J.; Fabian, Andrew; Roberts, Timothy P.; Heil, Lucy; Pinto, Ciro; Anderson, Gemma; Sutton, Andrew

    2015-12-01

    The lack of unambiguous detections of atomic features in the X-ray spectra of ultraluminous X-ray sources (ULXs) has proven a hindrance in diagnosing the nature of the accretion flow. The possible association of spectral residuals at soft energies with atomic features seen in absorption and/or emission and potentially broadened by velocity dispersion could therefore hold the key to understanding much about these enigmatic sources. Here we show for the first time that such residuals are seen in several sources and appear extremely similar in shape, implying a common origin. Via simple arguments we assert that emission from extreme colliding winds, absorption in a shell of material associated with the ULX nebula and thermal plasma emission associated with star formation are all highly unlikely to provide an origin. Whilst CCD spectra lack the energy resolution necessary to directly determine the nature of the features (i.e. formed of a complex of narrow lines or intrinsically broad lines), studying the evolution of the residuals with underlying spectral shape allows for an important, indirect test for their origin. The ULX NGC 1313 X-1 provides the best opportunity to perform such a test due to the dynamic range in spectral hardness provided by archival observations. We show through highly simplified spectral modelling that the strength of the features (in either absorption or emission) appears to anticorrelate with spectral hardness, which would rule out an origin via reflection of a primary continuum and instead supports a picture of atomic transitions in a wind or nearby material associated with such an outflow.

  16. The Course of Due Process.

    ERIC Educational Resources Information Center

    Getty, Laura A.; Summy, Sarah E.

    2004-01-01

    Discussion of due process rights for children with disabilities considers common issues leading to due process requests, due process procedures, hearing officers, procedural violations, effects of due process meetings, and areas for improvement (i.e., accountability, paperwork). Tables list categories of procedural violations with examples and…

  17. Solar powered absorption air conditioning

    NASA Astrophysics Data System (ADS)

    Vardon, J. M.

    1980-04-01

    Artificial means of providing or removing heat from the building are discussed along with the problem of the appropriate building design and construction for a suitable heat climate inside the building. The use of a lithium bromide-water absorption chiller, powered by a hot water store heated by an array of stationary flat collectors, is analyzed. An iterative method of predicting the cooling output from a LiBr-water absorption refrigeration plant having variable heat input is described and a model allowing investigation of the performance of a solar collector and thermal storage system is developed.

  18. Periodic microwave absorption in superconductors

    SciTech Connect

    Martinek, J.; Stankowski, J. )

    1994-08-01

    A model explaining the presence of a periodic train of microwave absorption lines in the magnetic modulated microwave absorption (MMMA) spectra of high- and low-temperature superconductors is proposed. The model assumes the occurrence of regular superconducting current loops, closed by Josephson junctions, in these materials. The system of such loops is considered within the basic model of the rf superconducting quantum interference device taking into account the effect of thermal fluctuations. The magnetic-field and temperature dependencies of the MMMA obtained on the basis of the proposed model are in qualitative agreement with experimental data.

  19. Absorption-heat-pump system

    DOEpatents

    Grossman, G.; Perez-Blanco, H.

    1983-06-16

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  20. Optical absorption analysis and optimization of gold nanoshells.

    PubMed

    Tuersun, Paerhatijiang; Han, Xiang'e

    2013-02-20

    Gold nanoshells, consisting of a nanoscale dielectric core coated with an ultrathin gold shell, have wide biomedical applications due to their strong optical absorption properties. Gold nanoshells with high absorption efficiencies can help to improve these applications. We investigate the effects of the core material, surrounding medium, core radius, and shell thickness on the absorption spectra of gold nanoshells by using the light-scattering theory of a coated sphere. Our results show that the position and intensity of the absorption peak can be tuned over a wide range by manipulating the above-mentioned parameters. We also obtain the optimal absorption efficiencies and structures of hollow gold nanoshells and gold-coated SiO(2) nanoshells embedded in water at wavelengths of 800, 820, and 1064 nm. The results show that hollow gold nanoshells possess the maximum absorption efficiency (5.42) at a wavelength of 800 nm; the corresponding shell thickness and core radius are 4.8 and 38.9 nm, respectively. They can be used as the ideal photothermal conversation particles for biomedical applications. PMID:23435006

  1. Gastrointestinal absorption of uranium compounds--a review.

    PubMed

    Konietzka, Rainer

    2015-02-01

    Uranium occurs naturally in soil and rocks, and therefore where it is present in water-soluble form it also occurs naturally in groundwater as well as in drinking water obtained from groundwater. Animal studies suggest that the toxicity of uranium is mainly due to its damage to kidney tubular cells following exposure to soluble uranium compounds. The assessments of the absorption of uranium via the gastrointestinal tract vary, and this has consequences for regulation, in particular the derivation of e.g. drinking water limit values. Absorption rates vary according to the nature and solubility of the compound in which uranium is presented to the test animals and depending on the animal species used in the test. No differences for sex have been observed for absorption in either animals or humans. However, human biomonitoring data do show that boys excrete significantly more uranium than girls. In animal studies neonates took up more uranium than adults or older children. Nutritional status, and in particular the iron content of the diet, have a marked influence on absorption, and higher uranium levels in food intake also appear to increase the absorption rate. If the pointers to an absorption mechanism competing with iron are correct, these mechanisms could also explain the relatively high concentration and chemical toxicity of uranium in the kidneys. It is here (and in the duodenum) that divalent metal transporter 1 (DMT1), which is primarily responsible for the passage of iron (or uranium?) through the cell membranes, is most strongly expressed. PMID:25263405

  2. Evidence for sulphur implantation in Europa's UV absorption band

    NASA Technical Reports Server (NTRS)

    Lane, A. L.; Nelson, R. M.; Matson, D. L.

    1981-01-01

    The UV spectral characteristics of the Galilean satellites are investigated (using data from the International Ultraviolet Explorer (IUE) spacecraft) as a function of the orbital position, large-scale areal variability, and temporal dynamics. The discovery of an absorption feature at 280 nm in Europa's reflection spectrum is reported and observations show that the absorption is strongest on the trailing hemisphere (central longitude 270 degrees). The feature resembles SO2 and seems to result from S-O bond formation between deeply implanted sulphur atoms and the adjacent damaged water-ice-lattice. The sulphur supposedly comes from energetic (hundreds of keV) sulphur ions that are present in the Jovian magnetosphere. An appropriate equilibrium condition can be found to match the observed spectral data if sputtering erosion occurs at no greater than approximately 20 meters per one billion years.

  3. Consistency of ARESE II Cloud Absorption Estimates and Sampling Issues

    NASA Technical Reports Server (NTRS)

    Oreopoulos, L.; Marshak, A.; Cahalan, R. F.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Data from three cloudy days (March 3, 21, 29, 2000) of the ARM Enhanced Shortwave Experiment II (ARESE II) were analyzed. Grand averages of broadband absorptance among three sets of instruments were compared. Fractional solar absorptances were approx. 0.21-0.22 with the exception of March 3 when two sets of instruments gave values smaller by approx. 0.03-0.04. The robustness of these values was investigated by looking into possible sampling problems with the aid of 500 nm spectral fluxes. Grand averages of 500 nm apparent absorptance cover a wide range of values for these three days, namely from a large positive (approx. 0.011) average for March 3, to a small negative (approximately -0.03) for March 21, to near zero (approx. 0.01) for March 29. We present evidence suggesting that a large part of the discrepancies among the three days is due to the different nature of clouds and their non-uniform sampling. Hence, corrections to the grand average broadband absorptance values may be necessary. However, application of the known correction techniques may be precarious due to the sparsity of collocated flux measurements above and below the clouds. Our analysis leads to the conclusion that only March 29 fulfills all requirements for reliable estimates of cloud absorption, that is, the presence of thick, overcast, homogeneous clouds.

  4. Damped Lyman-alpha absorption by disk galaxies with large redshifts. III. Intermediate-resolution spectroscopy

    SciTech Connect

    Turnshek, D.A.; Wolfe, A.M.; Lanzetta, K.M.; Briggs, F.H.; Cohen, R.D.; Multiple Mirror Telescope Observatory, Tucson, AZ; Pittsburgh Univ., PA; California Univ., La Jolla )

    1989-09-01

    New intermediate-resolution spectroscopy for six members of a sample of 68 moderate- to high-redshift QSOs is presented. Evidence is reported which indicates that seven strong absorption features in the QSO spectra are due to damped Ly-alpha absorption. A standard curve-of-growth analysis on five of the damped systems is performed, and relevant properties are tabulated and discussed. Six of the seven damped Ly-alpha systems have H I column densities of 2 x 10 to the 20th/sq cm or larger, while the remaining system has an H I column density of about 10 to the 20th/sq cm. It is suggested that damped Ly-alpha systems arise when a sight line intercepts a high-redshift protogalaxy disk containing a quiescent cloud component characterized by high column density and low effective velocity dispersion. At the same time, the sight line usually intercepts a broader turbulent component, which is identified as the halo, characterized by much lower column density and higher effective velocity dispersion. 42 refs.

  5. The Suzaku Observation of NGC 3516: Complex Absorption and the Broad and Narrow Fe K Lines

    NASA Technical Reports Server (NTRS)

    Markowitz, Alex; Reeves, James N.; Miniutti, Giovanni; Serlemitsos, Peter; Kunieda, Hideyo; Taqoob, Tahir; Fabian, Andrew C.; Fukazawa, Yasushi; Mushotzky, Richard; Okajima, Takashi; Gallo, Luigi; Awaki, Hisamitsu; Griffiths, Richard E.

    2007-01-01

    We present results from a 150 ksec Suzaku observation of the Seyfert 1 NGC 3516 in October 2005. The source was in a relatively highly absorbed state. Our best-fit model is consistent with partial covering by a lowly-ionized absorber with a column density near 5x10(exp 22) cm(exp -2) and with a covering fraction 96-100 percent. Narrow K-shell absorption features due to He- and H-like Fe confirm the presence of a high-ionization absorbing component as well. A broad Fe K(alpha) diskline is required in all fits, even after the complex absorption is taken into account; an additional partial-covering component is an inadequate substitute for the continuum curvature associated with the broad line. The narrow Fe Ka line at 6.4 keV is resolved, yielding a velocity width commensurate with the optical Broad Line Region. The strength of the Compton reflection hump suggests a contribution mainly from the broad Fe line origin. We include in our model soft band emission lines from He- and H-like ions and radiative recombination lines, consistent with photo-ionization, though a small contribution from collisional ionization is possible.

  6. Absorption Mode FT-ICR Mass Spectrometry Imaging

    SciTech Connect

    Smith, Donald F.; Kilgour, David P.; Konijnenburg, Marco; O'Connor, Peter B.; Heeren, Ronald M.

    2013-12-03

    Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here we present the first use of absorption mode for Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image and then these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode ?Datacubes? for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast.

  7. Active Galactic Nuclei Probed by QSO Absorption Lines

    NASA Astrophysics Data System (ADS)

    Misawa, Toru

    2007-07-01

    Quasars are the extremely bright nuclei found in about 10% of galaxies. A variety of absorption features (known collectively as quasar absorption lines) are detected in the rest-frame UV spectra of these objects. While absorption lines that have very broad widths originate in gas that is probably physocally related to the quasars, narrow absorption lines (NALs) were thought to arise in galaxies and/or in the intter-alacttic medium between the quasars and us. Using high-resolution spectra of quasars, it is found that a substantial fraction of NALs arise in gas in the immediate vicinity of the quasars. A dramatically variable, moderately-broad absorption line in the spectrum of the quasar HS 1603+3820l is also found. The variability of this line is monitored in a campaign with Subaru telescope. These observational results are compared to models for outflows from the quasars, specifically, models for accretion disk winds and evaporating obscuring tori. It is quite important to determine the mechanism of outflow because of its cosmological implications. The outflow could expel angular momentum from the accretion disk and enable quasars to accrete and shine. In addition, the outflow may also regulate star formation in the early stages of the assembly of the host galaxy and enrich the interstellar and intergalactic medium with metals.

  8. Powerful laser pulse absorption in partly homogenized foam plasma

    NASA Astrophysics Data System (ADS)

    Cipriani, M.; Gus'kov, S. Yu.; De Angelis, R.; Andreoli, P.; Consoli, F.; Cristofari, G.; Di Giorgio, G.; Ingenito, F.; Rupasov, A. A.

    2016-03-01

    The internal volume structure of a porous medium of light elements determines unique features of the absorption mechanism of laser radiation; the characteristics of relaxation and transport processes in the produced plasma are affected as well. Porous materials with an average density larger than the critical density have a central role in enhancing the pressure produced during the ablation by the laser pulse; this pressure can exceed the one produced by target direct irradiation. The problem of the absorption of powerful laser radiation in a porous material is examined both analytically and numerically. The behavior of the medium during the process of pore filling in the heated region is described by a model of viscous homogenization. An expression describing the time and space dependence of the absorption coefficient of laser radiation is therefore obtained from the model. A numerical investigation of the absorption of a nanosecond laser pulse is performed within the present model. In the context of numerical calculations, porous media with an average density larger than the critical density of the laser-produced plasma are considered. Preliminary results about the inclusion of the developed absorption model into an hydrodynamic code are presented.

  9. Estimating the Chromospheric Absorption of Transition Region Moss Emission

    NASA Astrophysics Data System (ADS)

    De Pontieu, Bart; Hansteen, Viggo H.; McIntosh, Scott W.; Patsourakos, Spiros

    2009-09-01

    Many models for coronal loops have difficulty explaining the observed EUV brightness of the transition region, which is often significantly less than theoretical models predict. This discrepancy has been addressed by a variety of approaches including filling factors and time-dependent heating, with varying degrees of success. Here, we focus on an effect that has been ignored so far: the absorption of EUV light with wavelengths below 912 Å by the resonance continua of neutral hydrogen and helium. Such absorption is expected to occur in the low-lying transition region of hot, active region loops that is colocated with cool chromospheric features and called "moss" as a result of the reticulated appearance resulting from the absorption. We use cotemporal and cospatial spectroheliograms obtained with the Solar and Heliospheric Observatory/SUMER and Hinode/EIS of Fe XII 1242 Å, 195 Å, and 186.88 Å, and compare the density determination from the 186/195 Å line ratio to that resulting from the 195/1242 Å line ratio. We find that while coronal loops have compatible density values from these two line pairs, upper transition region moss has conflicting density determinations. This discrepancy can be resolved by taking into account significant absorption of 195 Å emission caused by the chromospheric inclusions in the moss. We find that the amount of absorption is generally of the order of a factor of 2. We compare to numerical models and show that the observed effect is well reproduced by three-dimensional radiative MHD models of the transition region and corona. We use STEREO A/B data of the same active region and find that increased angles between line of sight and local vertical cause additional absorption. Our determination of the amount of chromospheric absorption of TR emission can be used to better constrain coronal heating models.

  10. ESTIMATING THE CHROMOSPHERIC ABSORPTION OF TRANSITION REGION MOSS EMISSION

    SciTech Connect

    De Pontieu, Bart; Hansteen, Viggo H.; McIntosh, Scott W.; Patsourakos, Spiros

    2009-09-10

    Many models for coronal loops have difficulty explaining the observed EUV brightness of the transition region, which is often significantly less than theoretical models predict. This discrepancy has been addressed by a variety of approaches including filling factors and time-dependent heating, with varying degrees of success. Here, we focus on an effect that has been ignored so far: the absorption of EUV light with wavelengths below 912 A by the resonance continua of neutral hydrogen and helium. Such absorption is expected to occur in the low-lying transition region of hot, active region loops that is colocated with cool chromospheric features and called 'moss' as a result of the reticulated appearance resulting from the absorption. We use cotemporal and cospatial spectroheliograms obtained with the Solar and Heliospheric Observatory/SUMER and Hinode/EIS of Fe XII 1242 A, 195 A, and 186.88 A, and compare the density determination from the 186/195 A line ratio to that resulting from the 195/1242 A line ratio. We find that while coronal loops have compatible density values from these two line pairs, upper transition region moss has conflicting density determinations. This discrepancy can be resolved by taking into account significant absorption of 195 A emission caused by the chromospheric inclusions in the moss. We find that the amount of absorption is generally of the order of a factor of 2. We compare to numerical models and show that the observed effect is well reproduced by three-dimensional radiative MHD models of the transition region and corona. We use STEREO A/B data of the same active region and find that increased angles between line of sight and local vertical cause additional absorption. Our determination of the amount of chromospheric absorption of TR emission can be used to better constrain coronal heating models.

  11. Monte Carlo Simulation for Quantification of Light Transport Features in Apples

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Light interaction with turbid biological materials involves absorption and scattering. Quantitative understanding of light propagation features in the fruit is critical to designing better optical systems for inspection of food quality. This article reports on the quantification of light propagation...

  12. Three featured plenary sessions

    NASA Astrophysics Data System (ADS)

    2012-07-01

    The conference included three plenary sessions. The plenary on Governance, Security, Economy, and the Ecosystem of the Changing Arctic featured Vera Alexander, president, Arctic Research Consortium of the U.S.; Alan Thornhill, chief environmental officer, U.S. Department of the Interior's Bureau of Ocean Energy Management; and Fran Ulmer, chair, U.S. Arctic Research Commission. A plenary on the U.N. Convention on the Law of the Sea featured Ambassador David Balton, deputy assistant secretary for oceans and fisheries, U.S. Department of State; and Rear Admiral Frederick Kenney Jr., judge advocate general and chief counsel, U.S. Coast Guard. The plenary on Science and the 21st Century featured Phil Keslin, chief technology officer, small lab within Google.

  13. On the 5D Extra-Force according to Basini Capozziello Ponce De Leon Formalism and five important features: Kar Sinha Gravitational Bending of Light, Chung Freese Superluminal Behaviour, Maartens Clarkson Black Strings, experimental measures of Extra Dimensions on board International Space Station (ISS) and the existence of the Particle Z due to a higher dimensional spacetime

    NASA Astrophysics Data System (ADS)

    Loup, Fernando

    2006-10-01

    We use the Conformal Metric as described in Kar Sinha work on Gravitational Bending of Light in a 5 D Spacetime to recompute the equations of the 5 D Force in Basini Capozziello Ponce De Leon Formalism and we arrive at a result that possesses some advantages. The equations of the Extra Force as proposed by Ponce De Leon are now more elegant in Conformal Formalism and many algebraic terms can be simplified or even suppressed. Also we recompute the Kar Sinha Gravitational Bending of Light affected by the presence of the Extra Dimension and analyze the Superluminal Chung Freese Features of this Formalism describing the advantages of the Chung Freese BraneWorld when compared to other Superluminal spacetime metrics (e.g. Warp Drive) and we describe why the Extra Dimension is invisible and how the Extra Dimension could be made visible at least in theory. We also examine the Maartens Clarkson Black Holes in 5 D (Black Strings) coupled to massive Kaluza Klein graviton modes predicted by Extra Dimensions theories and we study experimental detection of Extra Dimensions on-board LIGO and LISA Space Telescopes. We also propose the use of International Space Station (ISS) to measure the additional terms (resulting from the presence of Extra Dimensions) in the Kar Sinha Gravitational Bending of Light in Outer Space to verify if we really lives in a Higher Dimensional Spacetime. Also we demonstrate that Particle Z can only exist if the 5 D spacetime exists.

  14. Ultraviolet and Light Absorption Spectrometry.

    ERIC Educational Resources Information Center

    Hargis, L. G.; Howell, J. A.

    1984-01-01

    Reviews developments in ultraviolet and light absorption spectrometry from December 1981 through November 1983, focusing on the chemistry involved in developing suitable reagents, absorbing systems, and methods of determination, and on physical aspects of the procedures. Includes lists of spectrophotometric methods for metals, non-metals, and…

  15. Slow light and saturable absorption

    NASA Astrophysics Data System (ADS)

    Selden, A. C.

    2009-06-01

    Quantitative analysis of slow light experiments utilising coherent population oscillation (CPO) in a range of saturably absorbing media, including ruby and alexandrite, Er3+:Y2SiO5, bacteriorhodopsin, semiconductor quantum devices and erbium-doped optical fibres, shows that the observations may be more simply interpreted as saturable absorption phenomena. A basic two-level model of a saturable absorber displays all the effects normally associated with slow light, namely phase shift and modulation gain of the transmitted signal, hole burning in the modulation frequency spectrum and power broadening of the spectral hole, each arising from the finite response time of the non-linear absorption. Only where hole-burning in the optical spectrum is observed (using independent pump and probe beams), or pulse delays exceeding the limits set by saturable absorption are obtained, can reasonable confidence be placed in the observation of slow light in such experiments. Superluminal (“fast light”) phenomena in media with reverse saturable absorption (RSA) may be similarly explained.

  16. Migrant labor absorption in Malaysia.

    PubMed

    Nayagam, J

    1992-01-01

    The use of migrant workers to ease labor shortages caused by rapid industrialization in Malaysia during the twentieth century is examined. "This paper will focus on: (1) the extent, composition and distribution of migrant workers; (2) the labor shortage and absorption of migrant workers; and (3) the role of migrant workers in the government's economic restructuring process." PMID:12285766

  17. Comment on "Radiative Absorption Enhancements Due to the Mixing State of Atmospheric Black Carbon"

    NASA Astrophysics Data System (ADS)

    Jacobson, Mark Z.

    2013-01-01

    Cappa et al. (Reports, 31 August 2012, p. 1078) suggest that black carbon (BC) in a mixture absorbs only ~6% more sunlight than when volatile chemicals are evaporated from the mixture, and state that "many climate models may overestimate warming by BC." However, the authors misinterpret at least some model results and omit optical focusing at high relative humidity and of involatile components. Thus, their conclusion about model error is not demonstrated.

  18. Changes of blood plasma optical absorption spectrum due to bilirubin photoconversion

    NASA Astrophysics Data System (ADS)

    Altshuler, V. M.; Khanin, Yakov I.; Mironov, Yury A.

    1993-06-01

    This paper discusses some of our experimental results on the organism immunity increase caused by an intravenous UV irradiation of blood. The rabbits from an experimental group were treated with an optical fiber (620 micrometers core diameter) introduced to vena auricularis superficialis lateralis of the rabbits' ear. Pulsed UV laser emission was introduced through the optical fiber and rabbits' blood was irradiated for 10 minutes with the pulse repetition rate of 10 Hz. Subsequently, all rabbits from the experimental and a reference group were infected with the virulent strain of Staphylococcus aureus H 470. These results clearly indicate that the intravenous UV laser irradiation of blood had a positive therapeutic effect on the course of the animals' staphylococcal infection.

  19. Response to comment on "Radiative absorption enhancements due to the mixing state of atmospheric black carbon".

    PubMed

    Cappa, Christopher D; Onasch, Timothy B; Massoli, Paola; Worsnop, Douglas R; Bates, Timothy S; Cross, Eben S; Davidovits, Paul; Hakala, Jani; Hayden, Katherine L; Jobson, B Tom; Kolesar, Katheryn R; Lack, Daniel A; Lerner, Brian M; Li, Shao-Meng; Mellon, Daniel; Nuaaman, Ibraheem; Olfert, Jason S; Petäjä, Tuukka; Quinn, Patricia K; Song, Chen; Subramanian, R; Williams, Eric J; Zaveri, Rahul A

    2013-01-25

    Jacobson argues that our statement that "many climate models may overestimate warming by BC" has not been demonstrated. Jacobson challenges our results on the basis that we have misinterpreted some model results, omitted optical focusing under high relative humidity conditions and by involatile components, and because our measurements consist of only two locations over short atmospheric time periods. We address each of these arguments, acknowledging important issues and clarifying some misconceptions, and stand by our observations. We acknowledge that Jacobson identified one detail in our experimental technique that places an additional constraint on the interpretation of our observations and reduces somewhat the potential consequences of the stated implications. PMID:23349273

  20. Wet precipitation scavenging of soluble atmospheric trace gases due to chemical absorption in inhomogeneous atmosphere

    NASA Astrophysics Data System (ADS)

    Elperin, Tov; Fominykh, Andrew; Krasovitov, Boris

    2016-04-01

    We analyze the effects of irreversible chemical reactions of the first and higher orders and aqueous-phase dissociation reactions on the rate of trace gas scavenging by rain in the atmosphere with non-uniform concentration and temperature. We employ an one-dimensional model of precipitation scavenging of chemically active soluble gaseous pollutants that is valid for small gradients of temperature and concentration in the atmosphere. It is demonstrated that transient altitudinal distribution of concentration under the influence of rain is determined by the partial hyperbolic differential equation of the first order. Scavenging coefficients are calculated for wet removal of chlorine, nitrogen dioxide and sulfur dioxide for the exponential and linear initial altitudinal distributions of trace gases concentration in the atmosphere and linear and uniform altitudinal temperature distributions. Theoretical predictions of the dependence of the magnitude of the scavenging coefficient on rain intensity for sulfur dioxide are in a good agreement with the available atmospheric measurements.

  1. Energy absorption due to spatial resonance of Alfven waves at continuum tip

    NASA Astrophysics Data System (ADS)

    Chen, Eugene; Berk, Herb; Breizman, Boris; Zheng, Linjin

    2011-10-01

    We investigate the response of tokamak plasma to an external driving source. An impedance-like function depending on the driving frequency that is growing at a small rate, is calculated and interpreted with different source profiles. Special attention is devoted to the case where driving frequency approaches that of the TAE continuum tip. The calculation can be applied to the estimation of TAE damping rate by analytically continuing the inverse of the impedance function to the lower half plane. The root of the analytic continuation corresponds to the existence of a quasi-mode, from which the damping rate can be found.

  2. Aerosol Absorption and Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Stier, Philip; Seinfeld, J. H.; Kinne, Stefan; Boucher, Olivier

    2007-01-01

    We present a comprehensive examination of aerosol absorption with a focus on evaluating the sensitivity of the global distribution of aerosol absorption to key uncertainties in the process representation. For this purpose we extended the comprehensive aerosol-climate model ECHAM5-HAM by effective medium approximations for the calculation of aerosol effective refractive indices, updated black carbon refractive indices, new cloud radiative properties considering the effect of aerosol inclusions, as well as by modules for the calculation of long-wave aerosol radiative properties and instantaneous aerosol forcing. The evaluation of the simulated aerosol absorption optical depth with the AERONET sun-photometer network shows a good agreement in the large scale global patterns. On a regional basis it becomes evident that the update of the BC refractive indices to Bond and Bergstrom (2006) significantly improves the previous underestimation of the aerosol absorption optical depth. In the global annual-mean, absorption acts to reduce the shortwave anthropogenic aerosol top-of-atmosphere (TOA) radiative forcing clear-sky from -0.79 to -0.53 W m(sup -2) (33%) and all-sky from -0.47 to -0.13W m(sup -2 (72%). Our results confirm that basic assumptions about the BC refractive index play a key role for aerosol absorption and radiative forcing. The effect of the usage of more accurate effective medium approximations is comparably small. We demonstrate that the diversity in the AeroCom land-surface albedo fields contributes to the uncertainty in the simulated anthropogenic aerosol radiative forcings: the usage of an upper versus lower bound of the AeroCom land albedos introduces a global annual-mean TOA forcing range of 0.19W m(sup -2) (36%) clear-sky and of 0.12W m(sup -2) (92%) all-sky. The consideration of black carbon inclusions on cloud radiative properties results in a small global annual-mean all-sky absorption of 0.05W m(sup -2) and a positive TOA forcing perturbation of 0

  3. Escalator design features evaluation

    NASA Technical Reports Server (NTRS)

    Zimmerman, W. F.; Deshpande, G. K.

    1982-01-01

    Escalators are available with design features such as dual speed (90 and 120 fpm), mat operation and flat steps. These design features were evaluated based on the impact of each on capital and operating costs, traffic flow, and safety. A human factors engineering model was developed to analyze the need for flat steps at various speeds. Mat operation of escalators was found to be cost effective in terms of energy savings. Dual speed operation of escalators with the higher speed used during peak hours allows for efficient operation. A minimum number of flat steps required as a function of escalator speed was developed to ensure safety for the elderly.

  4. Al III, Si IV, and C IV absorption toward zeta Ophiuchi: Evidence for photionized and collisionally ionized gas

    NASA Technical Reports Server (NTRS)

    Sembach, Kenneth R.; Savage, Blair D.; Jenkins, Edward B.

    1994-01-01

    We present Goddard High-Resolution Spectrograph observations at 3.5 km/s resolution and signal-to-noise ratios of 30 to 60 for the Al III, Si IV, and N V absorption lines in the far-ultraviolet spectrum of the O9.5 V star zeat Ophiuchi. The measurement reveal three types of highly ionized gas along the 140 pc line of sight. (1) Narrow components of Al III (b = 4.3 km/s, the mean value of (v(helio)) = -7.8 km/s; b = 3.2 km/s, the mean value of (v(sub helio)) = -14.4 km/s) and Si IV (b = 5.3 km/s, the mean value of (v(sub helio)) = -15.0 km/s) trace photionized gas in the expanding H II region surrounding zeta Oph. The observed magnitude and direction of the velocity offset between the Al III and Si IV profiles can be explained by models of H II regions that incorporate expansion. Narrow C IV absorption associated with the H II region is not detected. Predictions of the expected amounts of Si IV and C IV overestimate the column densities of these ions by factors of 30 and more than 10, respectively. The discrepancy may be due to the effects of elemental depletions in the gas and/or to the interaction of the stellar wind with surrounding matter. (2) Broad (b = 15 to 18 km/s) and weak Si IV and C IV absorption components are detected near the mean value of (v(sub helio)) = -26 km/s. The high-ionization species associated with these absorption components are probably produced by electron collisional ionization in a heated gas. This absorption may be physically related to the zeta Oph bow shock ot to a cloud complex situated within the local interstellar medium at d less than 60 pc. The C IV to Si IV column density ratio in this gas is 8, a factor of 6 less than conductive interface models predict, but this discrepancy may be removed by considering the effects of self-photoionization within the cooling gas in the model calculations. (3) A broad (b = 13 km/s) and weak C IV absorption feature detected at the mean value of (v(sub helio)) = -61 km/s is not seen in other

  5. Nonlinear absorption of Alfven wave in dissipative plasma

    SciTech Connect

    Taiurskii, A. A. Gavrikov, M. B.

    2015-10-28

    We propose a method for studying absorption of Alfven wave propagation in a homogeneous non-isothermal plasma along a constant magnetic field, and relaxation of electron and ion temperatures in the A-wave. The absorption of a A-wave by the plasma arises due to dissipative effects - magnetic and hydrodynamic viscosities of electrons and ions and their elastic interaction. The method is based on the exact solution of two-fluid electromagnetic hydrodynamics of the plasma, which for A-wave, as shown in the work, are reduced to a nonlinear system of ordinary differential equations.

  6. Local disorder investigation in NiS(2-x)Se(x) using Raman and Ni K-edge x-ray absorption spectroscopies.

    PubMed

    Marini, C; Joseph, B; Caramazza, S; Capitani, F; Bendele, M; Mitrano, M; Chermisi, D; Mangialardo, S; Pal, B; Goyal, M; Iadecola, A; Mathon, O; Pascarelli, S; Sarma, D D; Postorino, P

    2014-11-12

    We report on Raman and Ni K-edge x-ray absorption investigations of a NiS(2-x)Se(x) (with x = 0.00, 0.50/0.55, 0.60, and 1.20) pyrite family. The Ni K-edge absorption edge shows a systematic shift going from an insulating phase (x = 0.00 and 0.50) to a metallic phase (x = 0.60 and 1.20). The near-edge absorption features show a clear evolution with Se doping. The extended x-ray absorption fine structure data reveal the evolution of the local structure with Se doping which mainly governs the local disorder. We also describe the decomposition of the NiS(2-x)Se(x) Raman spectra and investigate the weights of various phonon modes using Gaussian and Lorentzian profiles. The effectiveness of the fitting models in describing the data is evaluated by means of Bayes factor estimation. The Raman analysis clearly demonstrates the disorder effects due to Se alloying in describing the phonon spectra of NiS(2-x)Se(x) pyrites. PMID:25320052

  7. Emission from water vapor and absorption from other gases at 5-7.5 μm in Spitzer-IRS Spectra Of Protoplanetary Disks

    SciTech Connect

    Sargent, B. A.; Forrest, W.; Watson, Dan M.; Kim, K. H.; Richter, I.; Tayrien, C.; D'Alessio, P.; Calvet, N.; Furlan, E.; Green, J.; Pontoppidan, K.

    2014-09-10

    We present spectra of 13 T Tauri stars in the Taurus-Auriga star-forming region showing emission in Spitzer Space Telescope Infrared Spectrograph 5-7.5 μm spectra from water vapor and absorption from other gases in these stars' protoplanetary disks. Seven stars' spectra show an emission feature at 6.6 μm due to the ν{sub 2} = 1-0 bending mode of water vapor, with the shape of the spectrum suggesting water vapor temperatures >500 K, though some of these spectra also show indications of an absorption band, likely from another molecule. This water vapor emission contrasts with the absorption from warm water vapor seen in the spectrum of the FU Orionis star V1057 Cyg. The other 6 of the 13 stars have spectra showing a strong absorption band, peaking in strength at 5.6-5.7 μm, which for some is consistent with gaseous formaldehyde (H{sub 2}CO) and for others is consistent with gaseous formic acid (HCOOH). There are indications that some of these six stars may also have weak water vapor emission. Modeling of these stars' spectra suggests these gases are present in the inner few AU of their host disks, consistent with recent studies of infrared spectra showing gas in protoplanetary disks.

  8. Local disorder investigation in NiS2-xSex using Raman and Ni K-edge x-ray absorption spectroscopies

    NASA Astrophysics Data System (ADS)

    Marini, C.; Joseph, B.; Caramazza, S.; Capitani, F.; Bendele, M.; Mitrano, M.; Chermisi, D.; Mangialardo, S.; Pal, B.; Goyal, M.; Iadecola, A.; Mathon, O.; Pascarelli, S.; Sarma, D. D.; Postorino, P.

    2014-11-01

    We report on Raman and Ni K-edge x-ray absorption investigations of a NiS2-xSex (with x = 0.00, 0.50/0.55, 0.60, and 1.20) pyrite family. The Ni K-edge absorption edge shows a systematic shift going from an insulating phase (x = 0.00 and 0.50) to a metallic phase (x = 0.60 and 1.20). The near-edge absorption features show a clear evolution with Se doping. The extended x-ray absorption fine structure data reveal the evolution of the local structure with Se doping which mainly governs the local disorder. We also describe the decomposition of the NiS2-xSex Raman spectra and investigate the weights of various phonon modes using Gaussian and Lorentzian profiles. The effectiveness of the fitting models in describing the data is evaluated by means of Bayes factor estimation. The Raman analysis clearly demonstrates the disorder effects due to Se alloying in describing the phonon spectra of NiS2-xSex pyrites.

  9. Residential solar-absorption chiller thermal dynamics

    SciTech Connect

    Guertin, J.M.; Wood, B.D.; McNeill, B.W.

    1981-03-01

    Research is reported on the transient performance of a commercial residential 3 ton lithium bromide-water absorption chiller designed for solar firing. Emphasis was placed on separating the chiller response from that of the entire test facility so that its transient response could solely be observed and quantified. It was found that the entire system time response and thermal capacitance has a major impact on performance degradation due to transient operation. Tests run to ascertain computer algorithms which simulate system isolated chiller performance, revealed processes hitherto undocumented. Transient operation is simulated by three distinct algorithms associated with the three phases of chiller operation. The first phase is start up time. It was revealed during testing that the time required to reach steady state performance values, when the chiller was turned on, was a linear function of steady state water supply temperatures. The second phase is quasi steady state performance. Test facility's performance compared favorably with the manufacturer's published data. The third phase is the extra capacity produced during spin down. Spin down occurs when the hot water supply pump is turned off while the other system pumps remain operating for a few minutes, thus allowing extra chiller capacity to be realized. The computer algorithms were used to generate plots which show the operational surface of an isolated absorption chiller subjected to off design and transient operation.

  10. Laser engines operating by resonance absorption.

    PubMed

    Garbuny, M; Pechersky, M J

    1976-05-01

    The coherence properties and power levels of lasers available at present lend themselves to the remote operation of mechanical engines by resonance absorption in a working gas. Laser radiation is capable of producing extremely high temperatures in a gas. Limits to the achievable temperatures in the working gas of an engine are imposed by the solid walls and by loss of resonance absorption due to thermal saturation, bleaching, and dissociation. However, it is shown that by proper control of the laser beam in space, time, and frequency, as well as by choice of the absorbing gas, these limits are to a great extent removed so that very high temperatures are indeed attainable. The working gas is largely monatomic, preferably helium with the addition of a few volume percent of an absorber. Such a gas mixture, internally heated, permits an optimization of the expansion ratio, with resulting thermal efficiencies and work ratios, not achievable in conventional engines. A relationship between thermal efficiency and work ratio is derived that is quite general for the optimization condition. The performance of laser piston engines, turbines, and the Stirling cycle based on these principles is discussed and compared with conventional engine operation. Finally, a brief discussion is devoted to the possibility and concepts for the direct conversion of selective vibrational or electronic excitation into mechanical work, bypassing the translational degrees of freedom. PMID:20165143

  11. Percutaneous absorption of methimazole: an in vitro study of the absorption pharmacokinetics for two different vehicles.

    PubMed

    Hill, K E; Mills, P C; Jones, B R; Bolwell, C F; Aberdein, D; Chambers, J P

    2015-12-01

    The use of transdermal medications in cats has become popular in veterinary medicine due to the ease of administration compared to oral medication. However, the research to support systemic absorption of drugs applied to the pinna after transdermal administration in cats is limited. The aim of this study was to characterize the percutaneous absorption pharmacokinetics of methimazole in a lipophilic vehicle compared to methimazole in Pluronic(®) lecithin organogel (PLO) using a finite dose applied to feline ear skin in an in vitro Franz cell model. The two formulations of methimazole (10 mg) were applied to the inner stratum corneum of six pairs of feline ears. The receptor medium was sampled up to 30 h post-administration, and methimazole concentrations were measured using high-performance liquid chromatography (HPLC). Histological examination of all ears was undertaken as small differences in the thickness of ear skin may have contributed to inter-individual differences in methimazole absorption between six cats. Methimazole was absorbed more completely across the pinnal skin when administered in the lipophilic vehicle compared to administration in the PLO gel (P < 0.001). PMID:25683868

  12. Optical absorption of nanoporous silicon: quasiparticle band gaps and absorption spectra

    NASA Astrophysics Data System (ADS)

    Shi, Guangsha; Kioupakis, Emmanouil

    2013-03-01

    Silicon is an earth-abundant material of great importance in semiconductors electronics, but its photovoltaic applications are limited by the low absorption coefficient in the visible due to its indirect band gap. One strategy to improve the absorbance is to perforate silicon with nanoscale pores, which introduce carrier scattering that enables optical transitions across the indirect gap. We used density functional and many-body perturbation theory in the GW approximation to investigate the electronic and optical properties of porous silicon for various pore sizes, spacings, and orientations. Our calculations include up to 400 atoms in the unit cell. We will discuss the connection of the band-gap value and absorption coefficient to the underlying nanopore geometry. The absorption coefficient in the visible range is found to be optimal for appropriately chosen nanopore size, spacing, and orientation. Our work allows us to predict porous-silicon structures that may have optimal performance in photovoltaic applications. This research was supported as part of CSTEC, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science. Computational resources were provided by the DOE NERSC facility.

  13. Propagation-invariant classification of sounds in channels with dispersion and absorption.

    PubMed

    Okopal, Greg; Loughlin, Patrick J

    2010-11-01

    In a previous paper [G. Okopal et al., J. Acoust. Soc. Am. 123, 832-841 (2008)], a method to obtain features of a wave that are unaffected by dispersion, per mode, was developed for improving classification of underwater sounds (e.g., sonar backscatter). The current paper builds on this work and presents additional contributions. First, it is shown that the dispersion-invariant moments developed previously are not invariant to frequency-dependent attenuation (absorption); consequently, their classification performance degrades in such channels. Second, a feature extraction method is developed to obtain features that are invariant to dispersion, and to two forms of absorption (known a priori): namely, absorption that yields spectral magnitude attenuation (in dB) that is linear with frequency, and linear with log-frequency. Third, the relationship of these absorption- and dispersion-invariant moment (ADIM) features to the cepstrum of the wave is examined, and it is shown that cepstral moments are also invariant to dispersion, and to the first form of absorption for odd-order moments. Finally, simulations are conducted to illustrate the performance of the ADIMs and cepstral moments on classifying the backscatter from steel shells in a dispersive channel with absorption. Receiver operator characteristic curves quantify the superior discriminability of the ADIMs and cepstral moments compared to ordinary moments. PMID:21110584

  14. Main features of meiosis

    SciTech Connect

    1993-12-31

    Chapter 17, outlines the main features of meiosis, beginning with its significance and proceeding through the meiotic stages. Meiosis is the most important modification of mitosis because it is the reduction division that gives rise to the haploid generation in the life cycle. 17 refs., 6 figs.

  15. Assistive Technologies, Feature Issue.

    ERIC Educational Resources Information Center

    Wobschall, Rachel, Ed.; Lakin, Charlie, Ed.

    1995-01-01

    This feature issue of a newsletter on community integration of individuals with developmental disabilities considers the role of assistive technologies. It describes efforts to utilize consumer direction, public policy, creativity, energy, and professional know-how in the pursuit of technology-based opportunities to enhance community inclusion,…

  16. Feature- Spring 2010

    Cancer.gov

    NCI CAM News is a twice yearly newsletter produced by OCCAM to bring you information on the National Cancer Institute's latest CAM activities. Featured in the newsletter are: Highlights of NCI-sponsored CAM research Resources for researchers such as funding opportunities and grant writing workshops Upcoming meetings and lectures

  17. Retrieval interval mapping, a tool to optimize the spectral retrieval range in differential optical absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Vogel, L.; Sihler, H.; Lampel, J.; Wagner, T.; Platt, U.

    2012-06-01

    Remote sensing via differential optical absorption spectroscopy (DOAS) has become a standard technique to identify and quantify trace gases in the atmosphere. The technique is applied in a variety of configurations, commonly classified into active and passive instruments using artificial and natural light sources, respectively. Platforms range from ground based to satellite instruments and trace-gases are studied in all kinds of different environments. Due to the wide range of measurement conditions, atmospheric compositions and instruments used, a specific challenge of a DOAS retrieval is to optimize the parameters for each specific case and particular trace gas of interest. This becomes especially important when measuring close to the detection limit. A well chosen evaluation wavelength range is crucial to the DOAS technique. It should encompass strong absorption bands of the trace gas of interest in order to maximize the sensitivity of the retrieval, while at the same time minimizing absorption structures of other trace gases and thus potential interferences. Also, instrumental limitations and wavelength depending sources of errors (e.g. insufficient corrections for the Ring effect and cross correlations between trace gas cross sections) need to be taken into account. Most often, not all of these requirements can be fulfilled simultaneously and a compromise needs to be found depending on the conditions at hand. Although for many trace gases the overall dependence of common DOAS retrieval on the evaluation wavelength interval is known, a systematic approach to find the optimal retrieval wavelength range and qualitative assessment is missing. Here we present a novel tool to determine the optimal evaluation wavelength range. It is based on mapping retrieved values in the retrieval wavelength space and thus visualize the consequence of different choices of retrieval spectral ranges, e.g. caused by slightly erroneous absorption cross sections, cross correlations and

  18. Continuum Absorption Coefficient of Atoms and Ions

    NASA Technical Reports Server (NTRS)

    Armaly, B. F.

    1979-01-01

    The rate of heat transfer to the heat shield of a Jupiter probe has been estimated to be one order of magnitude higher than any previously experienced in an outer space exploration program. More than one-third of this heat load is due to an emission of continuum radiation from atoms and ions. The existing computer code for calculating the continuum contribution to the total load utilizes a modified version of Biberman's approximate method. The continuum radiation absorption cross sections of a C - H - O - N ablation system were examined in detail. The present computer code was evaluated and updated by being compared with available exact and approximate calculations and correlations of experimental data. A detailed calculation procedure, which can be applied to other atomic species, is presented. The approximate correlations can be made to agree with the available exact and experimental data.

  19. Non-Voigt Lyalpha Absorption Line Profiles.

    PubMed

    Outram; Carswell; Theuns

    2000-02-01

    Recent numerical simulations have lead to a paradigm shift in our understanding of the intergalactic medium and the loss of a physical justification for Voigt profile fitting of the Lyalpha forest. Many individual lines seen in simulated spectra have significant departures from the Voigt profile, yet could be well fitted by a blend of two or more such lines. We discuss the expected effect on the line profiles due to ongoing gravitational structure formation and Hubble expansion. We develop a method to detect departures from Voigt profiles of the absorption lines in a statistical way and apply this method to simulated Lyalpha forest spectra, confirming that the profiles seen do statistically differ from Voigt profiles. PMID:10622758

  20. Sevelamer carbonate markedly reduces levothyroxine absorption.

    PubMed

    Iovino, Michele; Iovine, Nicola; Petrosino, Alfanso; Giagulli, Vito A; Licchelli, Brunella; Guastamacchia, Edoardo; Triggiani, Vincenzo

    2014-01-01

    We report the case of a young woman affected by hypothyroidism due to Hashimoto's thyroiditis, previously well compensated with a full replacement therapy (150 mcg/day of levothyroxine), presenting a clinical picture of myxedema, with a TSH=650 mU/L. Two years earlier she had started a dialysis treatment because of a chronic renal failure and had been under treatment for the last 18 months with sevelamer carbonate, a phosphate binder. No improvement of clinical conditions nor reduction in TSH serum levels was observed even on increasing the dose of levothyroxine up to 300 mcg/day, whereas euthyroidism finally restored by administering the first morning dose of sevelamer carbonate at least 4 hours after levothyroxine administration. This case shows that sevelamer carbonate, in analogy with what has been already reported for sevelamer hydrochloride, can interfere with levothyroxine absorption leading to a condition of hypothyroidism in patients previously well compensated with a given replacement dose. PMID:25183496

  1. Derivation of water vapour absorption cross-sections in the red region

    NASA Technical Reports Server (NTRS)

    Lal, M.; Chakrabarty, D. K.

    1994-01-01

    Absorption spectrum in 436 to 448 nm wavelength region gives NO2 and O3 column densities. This spectrum can also give H2O column density. The spectrum in the range of 655 to 667 nm contains absorption due to NO3 and H2O. Combining the absorption spectra in the wavelength ranges of 436 to 448 and 655 to 667 nm, water vapor absorption cross-sections in this range comes out to be of the order of 2.0 x 10(exp -24) cm(exp -2).

  2. Inhibitory effect of Ipomoea aquatica extracts on glucose absorption using a perfused rat intestinal preparation.

    PubMed

    Sokeng, S D; Rokeya, B; Hannan, J M A; Junaida, K; Zitech, P; Ali, L; Ngounou, G; Lontsi, D; Kamtchouing, P

    2007-12-01

    Investigations were carried out to evaluate the effect of Ipomoea aquatica aqueous and dichloromethane/methanol extracts on the glucose absorption using a rat intestinal preparation in situ. Extracts orally tested at the dose of 160 mg/kg exerted a significant inhibitory effect on glucose absorption when compared with control animals. The most pronounced effect was observed with the aqueous extract. Ouabain used as reference inhibitor strongly inhibited glucose absorption. On the other hand both plant extracts inhibited the gastrointestinal motility suggesting that the inhibition of glucose absorption is not due to the acceleration of intestinal transit. PMID:17651914

  3. Direct measurements of nonlinear absorption and refraction in solutions of phthalocyanines

    NASA Technical Reports Server (NTRS)

    Wei, T. H.; Hagan, D. J.; Sence, M. J.; Van Stryland, E. W.; Perry, J. W.; Coulter, D. R.

    1992-01-01

    Direct measurements are reported of the excited singlet-state absorption cross section and the associated nonlinear refractive cross section using picosecond pulses at 532 nm in solutions of phthalocyanine and naphthalocyanine dyes. By monitoring the transmittance and far-field spatial beam distortion for different pulsewidths in the picosecond regime, it is shown that both the nonlinear absorption and refraction are fluence (energy-per-unit-area) rather than irradiance dependent. Thus, excited-state absorption is the dominant nonlinear absorption process, and the observed nonlinear refraction is also due to real population excitation.

  4. Spectral features of biogenic calcium carbonates and implications for astrobiology

    NASA Astrophysics Data System (ADS)

    Berg, B. L.; Ronholm, J.; Applin, D. M.; Mann, P.; Izawa, M.; Cloutis, E. A.; Whyte, L. G.

    2014-09-01

    The ability to discriminate biogenic from abiogenic calcium carbonate (CaCO3) would be useful in the search for extant or extinct life, since CaCO3 can be produced by both biotic and abiotic processes on Earth. Bioprecipitated CaCO3 material was produced during the growth of heterotrophic microbial isolates on medium enriched with calcium acetate or calcium citrate. These biologically produced CaCO3, along with natural and synthetic non-biologically produced CaCO3 samples, were analysed by reflectance spectroscopy (0.35-2.5 μm), Raman spectroscopy (532 and 785 nm), and laser-induced fluorescence spectroscopy (365 and 405 nm excitation). Optimal instruments for the discrimination of biogenic from abiogenic CaCO3 were determined to be reflectance spectroscopy, and laser-induced fluorescence spectroscopy. Multiple absorption features in the visible light region occurred in reflectance spectra for most biogenic CaCO3 samples, which are likely due to organic pigments. Multiple fluorescence peaks occurred in emission spectra (405 nm excitation) of biogenic CaCO3 samples, which also are best attributed to the presence of organic compounds; however, further analyses must be performed in order to better determine the cause of these features to establish criteria for confirming the origin of a given CaCO3 sample. Raman spectroscopy was not useful for discrimination since any potential Raman peaks in spectra of biogenic carbonates collected by both the 532 and 785 nm lasers were overwhelmed by fluorescence. However, this also suggests that biogenic carbonates may be identified by the presence of this organic-associated fluorescence. No reliable spectroscopic differences in terms of parameters such as positions or widths of carbonate-associated absorption bands were found between the biogenic and abiogenic carbonate samples. These results indicate that the presence or absence of organic matter intimately associated with carbonate minerals is the only potentially useful

  5. Absorption coefficients of selected explosives and related compounds in the range of 0.1-2.8 THz.

    PubMed

    Chen, Jian; Chen, Yunqing; Zhao, Hongwei; Bastiaans, Glenn J; Zhang, X-C

    2007-09-17

    We have investigated the absorption spectra of seventeen explosives and related compounds (ERCs) by using terahertz time-domain spectroscopy in the 0.1-2.8 THz region. Most of these substances show characteristic absorption features in this frequency range. The measured absorption coefficients of these ERCs form a database, which is of great importance for biochemical, defense and security related applications. PMID:19547570

  6. Theoretical Study of New Combined Absorption-Ejector Refrigeration System

    NASA Astrophysics Data System (ADS)

    Abed, A. M.; Sopian, K.; Alghoul, M. A.; Al-Shamani, A. N.; Ruslan, M. H.; Mat, S.

    2015-09-01

    An improved system of the new combined single stage absorption cycle operated with NH3/H2O as working fluid was performed. In order to enhance performance the cycle a new configuration of absorption system was utilized. The performances of two configurations of the combined absorption cycle were compared; a) with common solution heat exchanger and b) divided the streamline of solution heat exchanger to recover the internal heat. Based on the analysis, it has been shown that the second configuration a significant reduction of the required generator and absorber loads by about 20% and 17% respectively, with increased coefficient of performance (COP) about 12% compared to the first configuration. This improvement in the overall COP is found due to improve energy utilization efficiency significantly.

  7. Broadband solar absorption enhancement via periodic nanostructuring of electrodes

    PubMed Central

    Adachi, Michael M.; Labelle, André J.; Thon, Susanna M.; Lan, Xinzheng; Hoogland, Sjoerd; Sargent, Edward H.

    2013-01-01

    Solution processed colloidal quantum dot (CQD) solar cells have great potential for large area low-cost photovoltaics. However, light utilization remains low mainly due to the tradeoff between small carrier transport lengths and longer infrared photon absorption lengths. Here, we demonstrate a bottom-illuminated periodic nanostructured CQD solar cell that enhances broadband absorption without compromising charge extraction efficiency of the device. We use finite difference time domain (FDTD) simulations to study the nanostructure for implementation in a realistic device and then build proof-of-concept nanostructured solar cells, which exhibit a broadband absorption enhancement over the wavelength range of λ = 600 to 1100 nm, leading to a 31% improvement in overall short-circuit current density compared to a planar device containing an approximately equal volume of active material. Remarkably, the improved current density is achieved using a light-absorber volume less than half that typically used in the best planar devices. PMID:24121519

  8. Optical absorption of ion-beam sputtered amorphous silicon coatings

    NASA Astrophysics Data System (ADS)

    Steinlechner, Jessica; Martin, Iain W.; Bassiri, Riccardo; Bell, Angus; Fejer, Martin M.; Hough, Jim; Markosyan, Ashot; Route, Roger K.; Rowan, Sheila; Tornasi, Zeno

    2016-03-01

    Low mechanical loss at low temperatures and a high index of refraction should make silicon optimally suited for thermal noise reduction in highly reflective mirror coatings for gravitational wave detectors. However, due to high optical absorption, amorphous silicon (aSi) is unsuitable for being used as a direct high-index coating material to replace tantala. A possible solution is a multimaterial design, which enables exploitation of the excellent mechanical properties of aSi in the lower coating layers. The possible number of aSi layers increases with absorption reduction. In this work, the optimum heat treatment temperature of aSi deposited via ion-beam sputtering was investigated and found to be 450 °C . For this temperature, the absorption after deposition of a single layer of aSi at 1064 nm and 1550 nm was reduced by more than 80%.

  9. Focused optical and acoustic beams in media with nonlinear absorption

    NASA Astrophysics Data System (ADS)

    Rudenko, O. V.; Sukhorukov, A. A.

    1996-11-01

    Optical and acoustic beams are known to be useful for medical and biological applications, such as diagnostics, surgery, etc. At high intensities both nonlinear lens effects and nonlinear absorption can be significant for the beams. The nonlinear absorption arises due to two-photon optical processes or acoustic shock wave formation. The present work is devoted to the theoretical description of nonlinear beam propagation and focal spot formation taking into account the competition between focusing, diffraction and absorption. We derived a new nonlinear integro- differential equation describing the spatial evolution of the beam width. The general analytical solution of this equation is obtained for arbitrary boundary conditions. The simple formulas are derived for the angle divergence in the far field, as well as for beam width at nonlinear waist. The results of the analysis of these key parameters in different situations are presented.

  10. Dimension effect in lattice absorption of silicon carbide

    NASA Astrophysics Data System (ADS)

    Sokolov, I. A.; Ordin, S. V.

    2005-12-01

    We report high-sensitive experimental investigations of the SiC powders transmission spectra in the lattice oscillations region. For the SiC powders with the grain size of the order of the wave length the transmission minimum is shifted to the low-frequency range with respect to the transverse oscillation frequency of a single crystal ω T orresponding to phonon absorption with greater wave vectors. The decrease of the grain size leads to the shift and narrowing of the lattice absorption band to the high-frequency region. The observed change in the form and position of an absorption band corresponds to the narrowing of an optical phonon band due to decrease of the crystalline grain size, and approaching the lattice oscillation frequency to the frequency of molecular oscillations of Si-C in carbosilane owing to the surface energy contribution increase.

  11. 44th Annual Anomalous Absorption Conference

    SciTech Connect

    Beg, Farhat

    2014-03-03

    Conference Grant Report July 14, 2015 Submitted to the U. S. Department of Energy Attn: Dr. Sean Finnegan By the University of California, San Diego 9500 Gilman Drive La Jolla, California 92093 On behalf of the 44th Annual Anomalous Absorption Conference 8-13 June 2014, in Estes Park, Colorado Support Requested: $10,100 Amount expended: $3,216.14 Performance Period: 1 March 20 14 to 28 February 20 15 Principal Investigator Dr. Farhat Beg Center for Energy Research University of California, San Diego 9500 Gilman Drive La Jolla, California 92093-0417 858-822-1266 (telephone) 858-534-4543 (fax) fbeg@ucsd.edu Administrative Point of Contact: Brandi Pate, 858-534-0851, blpate®ucsd.edu I. Background The forty-fourth Anomalous Absorption Conference was held in Estes Park, Colorado from June 5-8, 2014 (aac2014.ucsd.edu). The first Anomalous Absorption Conference was held in 1971 to assemble experts in the poorly understood area of laser-plasma absorption. The goal of that conference was to address the anomalously large laser absorption seen in plasma experiments with respect to the laser absorption predicted by linear plasma theory. Great progress in this research area has been made in the decades since that first meeting, due in part to the scientific interactions that have occurred annually at this conference. Specifically, this includes the development of nonlinear laser-plasma theory and the simulation of laser interactions with plasmas. Each summer since that first meeting, this week-long conference has been held at unique locations in North America as a scientific forum for intense scientific exchanges relevant to the interaction of laser radiation with plasmas. Responsibility for organizing the conference has traditional rotated each year between the major Inertial Confinement Fusion (ICF) laboratories and universities including LANL, LLNL, LLE, UCLA UC Davis and NRL. As the conference has matured over the past four decades, its technical footprint has expanded

  12. The Intestinal Absorption of Folates

    PubMed Central

    Visentin, Michele; Diop-Bove, Ndeye; Zhao, Rongbao; Goldman, I. David

    2014-01-01

    The properties of intestinal folate absorption were documented decades ago. However, it was only recently that the proton-coupled folate transporter (PCFT) was identified and its critical role in folate transport across the apical brush-border membrane of the proximal small intestine established by the loss-of-function mutations identified in the PCFT gene in subjects with hereditary folate malabsorption and, more recently, by the Pcft-null mouse. This article reviews the current understanding of the properties of PCFT-mediated transport and how they differ from those of the reduced folate carrier. Other processes that contribute to the transport of folates across the enterocyte, along with the contribution of the enterohepatic circulation, are considered. Important unresolved issues are addressed, including the mechanism of intestinal folate absorption in the absence of PCFT and regulation of PCFT gene expression. The impact of a variety of ions, organic molecules, and drugs on PCFT-mediated folate transport is described. PMID:24512081

  13. The intestinal absorption of folates.

    PubMed

    Visentin, Michele; Diop-Bove, Ndeye; Zhao, Rongbao; Goldman, I David

    2014-01-01

    The properties of intestinal folate absorption were documented decades ago. However, it was only recently that the proton-coupled folate transporter (PCFT) was identified and its critical role in folate transport across the apical brush-border membrane of the proximal small intestine established by the loss-of-function mutations identified in the PCFT gene in subjects with hereditary folate malabsorption and, more recently, by the Pcft-null mouse. This article reviews the current understanding of the properties of PCFT-mediated transport and how they differ from those of the reduced folate carrier. Other processes that contribute to the transport of folates across the enterocyte, along with the contribution of the enterohepatic circulation, are considered. Important unresolved issues are addressed, including the mechanism of intestinal folate absorption in the absence of PCFT and regulation of PCFT gene expression. The impact of a variety of ions, organic molecules, and drugs on PCFT-mediated folate transport is described. PMID:24512081

  14. Maximum entropy and drug absorption.

    PubMed

    Charter, M K; Gull, S F

    1991-10-01

    The application of maximum entropy to the calculation of drug absorption rates was introduced in an earlier paper. Here it is developed further, and the whole procedure is presented as a problem in scientific inference to be solved using Bayes' theorem. Blood samples do not need to be taken at equally spaced intervals, and no smoothing, interpolation, extrapolation, or other preprocessing of the data is necessary. The resulting input rate estimates are smooth and physiologically realistic, even with noisy data, and their accuracy is quantified. Derived quantities such as the proportion of the dose absorbed, and the mean and median absorption times, are also obtained, together with their error estimates. There are no arbitrarily valued parameters in the analysis, and no specific functional form, such as an exponential or polynomial, is assumed for the input rate functions. PMID:1783989

  15. Optical absorption in trilayer graphene

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Zhang, Fan; Niu, Qian

    2013-03-01

    We use a low energy effective model to analyze the optical responses of trilayer graphene samples. We first show that optical absorption of the ABA-stacked trilayer has strong dependence on both the Fermi energy and optical frequency, which is in sharp contrast to that of ABC-stacked trilayer graphene. Secondly, we are able to determine the possible existence of trigonal warping effects in the bandstructure of ABC-stacked trilayer graphene by a divergence in the absorption spectra at around 10 meV. In addition, we can partially distinguish the vairious broken symmetry states driven by electron-electron interactions in ABC-stacked trilayer graphene. In particular, the quantum anomalous Hall (QAH) state is sensitive to the polarization of the incident light, giving a way to detect its possible existence.

  16. Extracting features to recognize partially occluded objects

    NASA Astrophysics Data System (ADS)

    Koch, Mark W.; Ramamurthy, Arjun

    1991-12-01

    Noisy objects, partially occluded objects, and objects in random positions and orientations cause significant problems for current robotic vision systems. In the past, an association graph has formed the basis for many model based matching methods. However, the association graph has many false nodes due to local and noisy features. Objects having similar local structures create many false arcs in the association graph. The maximal clique recursive and tree search procedures for finding sets of structurally compatible matches have exponential time complexity, due to these false arcs and nodes. This represents a real problem as the number of objects appearing in the scene and the model set size increase. Our approach is similar to randomized string matching algorithms. Points on edges represent the model features. A fingerprint defines a subset of model features that uniquely identify the model. These fingerprints remove the ambiguities and inconsistencies present in the association graph and eliminate the problems of Turney's connected salient features. The vision system chooses the fingerprints at random, preventing a knowledgeable adversary from constructing examples that destroy the advantages of fingerprinting. Fingerprints consist of local model features called point vectors. We have developed a heuristic approach for extracting fingerprints from a set of model objects. A list of connected and unconnected scene edges represent the scene. A Hough transform type approach matches model fingerprints to scene features. Results are given for scenes containing varying amounts of occlusion.

  17. Photodetector with enhanced light absorption

    DOEpatents

    Kane, James

    1985-01-01

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  18. Absorption properties of identical atoms

    NASA Astrophysics Data System (ADS)

    Sancho, Pedro

    2013-09-01

    Emission rates and other optical properties of multi-particle systems in collective and entangled states differ from those in product ones. We show the existence of similar effects in the absorption probabilities for (anti)symmetrized states of two identical atoms. The effects strongly depend on the overlapping between the atoms and differ for bosons and fermions. We propose a viable experimental verification of these ideas.

  19. Geometrical interpretation of optical absorption

    SciTech Connect

    Monzon, J. J.; Barriuso, A. G.; Sanchez-Soto, L. L.; Montesinos-Amilibia, J. M.

    2011-08-15

    We reinterpret the transfer matrix for an absorbing system in very simple geometrical terms. In appropriate variables, the system appears as performing a Lorentz transformation in a (1 + 3)-dimensional space. Using homogeneous coordinates, we map that action on the unit sphere, which is at the realm of the Klein model of hyperbolic geometry. The effects of absorption appear then as a loxodromic transformation, that is, a rhumb line crossing all the meridians at the same angle.

  20. Multiphonon infrared absorption in silicon

    NASA Astrophysics Data System (ADS)

    Pradhan, M. M.; Garg, R. K.; Arora, M.

    1987-01-01

    Investigations have been carried out on silicon crystals, grown by float zone (FZ) and Czochralski (CZ) methods, of infrared absorption bands using a Fourier transform infrared spectrophotometer. Multiphonon bands are identified in the light of recent theoretical calculations based on the total energy of silicon crystal lattice. Theoretical results of Ihm et al. (1) and Yin and Cohen (2,3) are found to be in good agreement with the experimental observations of multiphonon infrared bands.

  1. Abnormal passive chloride absorption in cystic fibrosis jejunum functionally opposes the classic chloride secretory defect

    PubMed Central

    Russo, Michael A.; Högenauer, Christoph; Coates, Stephen W.; Santa Ana, Carol A.; Porter, Jack L.; Rosenblatt, Randall L.; Emmett, Michael; Fordtran, John S.

    2003-01-01

    Due to genetic defects in apical membrane chloride channels, the cystic fibrosis (CF) intestine does not secrete chloride normally. Depressed chloride secretion leaves CF intestinal absorptive processes unopposed, which results in net fluid hyperabsorption, dehydration of intestinal contents, and a propensity to inspissated intestinal obstruction. This theory is based primarily on in vitro studies of jejunal mucosa. To determine if CF patients actually hyperabsorb fluid in vivo, we measured electrolyte and water absorption during steady-state perfusion of the jejunum. As expected, chloride secretion was abnormally low in CF, but surprisingly, there was no net hyperabsorption of sodium or water during perfusion of a balanced electrolyte solution. This suggested that fluid absorption processes are reduced in CF jejunum, and further studies revealed that this was due to a marked depression of passive chloride absorption. Although Na+-glucose cotransport was normal in the CF jejunum, absence of passive chloride absorption completely blocked glucose-stimulated net sodium absorption and reduced glucose-stimulated water absorption 66%. This chloride absorptive abnormality acts in physiological opposition to the classic chloride secretory defect in the CF intestine. By increasing the fluidity of intraluminal contents, absence of passive chloride absorption may reduce the incidence and severity of intestinal disease in patients with CF. PMID:12840066

  2. Intrinsic Feature Motion Tracking

    2013-03-19

    Subject motion during 3D medical scanning can cause blurring and artifacts in the 3D images resulting in either rescans or poor diagnosis. Anesthesia or physical restraints may be used to eliminate motion but are undesirable and can affect results. This software measures the six degree of freedom 3D motion of the subject during the scan under a rigidity assumption using only the intrinsic features present on the subject area being monitored. This movement over timemore » can then be used to correct the scan data removing the blur and artifacts. The software acquires images from external cameras or images stored on disk for processing. The images are from two or three calibrated cameras in a stereo arrangement. Algorithms extract and track the features over time and calculate position and orientation changes relative to an initial position. Output is the 3D position and orientation change measured at each image.« less

  3. Unidentified Infrared Emission Features

    NASA Astrophysics Data System (ADS)

    Joblin, Christine

    2015-03-01

    When referring to unidentified infrared emission features, one has in mind the series of aromatic IR bands (AIBs) between 3.3 and 15 μm that are observed in emission in many environments where UV photons irradiate interstellar matter. These bands are now used by astronomers to classify objects and characterize local physical conditions. However, a deep analysis cannot proceed without understanding the properties of the band carriers. Large polycyclic aromatic hydrocarbon molecules are attractive candidates but interstellar species are still poorly characterized. Various studies emphasize the need for tackling the link between molecular aromatic species, aliphatic material and very small carbonaceous grains. Other unidentified emission features such as the 6.9, 21 and 30 μm bands could be involved in the evolutionary scenario.

  4. Intrinsic Feature Motion Tracking

    SciTech Connect

    Goddard, Jr., James S.

    2013-03-19

    Subject motion during 3D medical scanning can cause blurring and artifacts in the 3D images resulting in either rescans or poor diagnosis. Anesthesia or physical restraints may be used to eliminate motion but are undesirable and can affect results. This software measures the six degree of freedom 3D motion of the subject during the scan under a rigidity assumption using only the intrinsic features present on the subject area being monitored. This movement over time can then be used to correct the scan data removing the blur and artifacts. The software acquires images from external cameras or images stored on disk for processing. The images are from two or three calibrated cameras in a stereo arrangement. Algorithms extract and track the features over time and calculate position and orientation changes relative to an initial position. Output is the 3D position and orientation change measured at each image.

  5. North Polar Features

    NASA Technical Reports Server (NTRS)

    2004-01-01

    28 November 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows banded terrain of the north polar region of Mars. The bands are exposures of layered material, possibly composed of dust and ice. The dark, rounded to elliptical mounds in this image might be the locations of ancient sand dunes that were completely buried in the north polar layered material. In more recent times, these mounds have been exhumed from within the layered material. Alternatively, the dark features are not ancient, exhumed dunes, but perhaps the remnants of a dark layer of material that once covered the entire area shown in the image. These features are located near 79.9oN, 31.4oW. The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  6. GAX absorption cycle design process

    SciTech Connect

    Priedeman, D.K.; Christensen, R.N.

    1999-07-01

    This paper presents an absorption system design process that relies on computer simulations that are validated by experimental findings. An ammonia-water absorption heat pump cycle at 3 refrigeration tons (RT) and chillers at 3.3 RT and 5 RT (10.5 kW, 11.6 kW, and 17.6 kW) were initially modeled and then built and tested. The experimental results were used to calibrate both the cycle simulation and the component simulations, yielding computer design routines that could accurately predict component and cycle performance. Each system was a generator-absorber heat exchange (GAX) cycle, and all were sized for residential and light commercial use, where very little absorption equipment is currently used. The specific findings of the 5 RT (17.6 kW) chiller are presented. Modeling incorporated a heat loss from the gas-fired generator and pressure drops in both the evaporator and absorber. Simulation results and experimental findings agreed closely and validated the modeling method and simulation software.

  7. Purge needs in absorption chillers

    SciTech Connect

    Murray, J.G. )

    1993-10-01

    Absorption chillers are regaining a significant share of large tonnage chiller sales, such as they had 20 years ago. Gas-fired chillers are now available that have a base energy (ultimate fuel usage) consumption rate per ton comparable to that in electric units. Effective purging in an absorption chiller is an absolute necessity to achieve the low chilled water temperature needed for dehumidification and to fully benefit from the energy savings offered by double-effect cycles. Although the purge system is usually not shown on the typical cycle schematic, its proper functioning is a key requirement for satisfactory machine operation. This article discusses the effect of noncondensible (N/C) gases on the absorption cooling process and the basics of purge systems. In addition, the article discusses the rationale for the important design step of selecting the location of the N/C probe, and discusses purge systems applicable to the direct-fired, double-effect machines now entering the marketplace.

  8. New Electrocardiographic Features in Brugada Syndrome

    PubMed Central

    de Luna, Antonio B; García-Niebla, Javier; Baranchuk, Adrian

    2014-01-01

    Brugada syndrome is a genetically determined familial disease with autosomal dominant transmission and variable penetrance, conferring a predisposition to sudden cardiac death due to ventricular arrhythmias. The syndrome is characterized by a typical electrocardiographic pattern in the right precordial leads. This article will focus on the new electrocardiographic features recently agreed on by expert consensus helping to identify this infequent electrocardiographic pattern. PMID:24827804

  9. Isidis Planitia Features

    NASA Technical Reports Server (NTRS)

    2004-01-01

    26 June 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the most typical features of Isidis Planitia at full (1.5 meters -- 5 feet -- per pixel) resolution. The typical features are: (1) light-toned, ripple-like dunes and (2) mounds with summit pits. The dunes are formed by wind. The double-cone feature in the lower right quarter of the image is similar to many mounds and chains of mounds or cones found all across Isidis Planitia. These were seen at lower resolution in Viking orbiter images in the 1970s and were generally considered to be either small volcanoes or ice-cored mounds known as pingoes. With high resolution MOC images, it became apparent that many of these mounds may simply be the remnants of crater and pit chain floors, elevated above the surrounding plains as the layers of rock into which they formed were stripped away. Like much of Mars, there are more questions than answers. This image is located near 8.6oN, 268.2oW, and covers an area about 1.1 km (0.7 mi) wide. Sunlight illuminates the scene from the left/lower left.

  10. Ceraunius Tholus Feature

    NASA Technical Reports Server (NTRS)

    2004-01-01

    11 December 2004 Today's Mars Picture of the Day features two images. The top picture is a mosaic of Viking orbiter images acquired in the late 1970s. The lower image is a high resolution picture from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). The Viking mosaic shows Ceraunius Tholus, a volcano in the Tharsis region that was first viewed in images obtained by Mariner 9 in 1972. Several channels run down the slope of the Ceraunius Tholus volcano. The deepest of those channels ends in an elliptical crater. The elliptical crater was formed by a very oblique meteor impact. Where the channel meets the floor of the elliptical crater, there is a small mound of material. Presumably, this material was deposited in the elliptical crater after running down through the channel on the volcano's northwest flank.

    Near the top/center of the mound in the elliptical crater is a small, circular depression. Some have speculated for years that this depression is related to volcanism, others thought that it may be an impact crater. The MGS MOC image (lower of the two images) shows that crater. It is not the source of lava flows or any other volcanic features. Most likely, it is an old impact crater. This feature is located near 25.2oN, 97.7oW. The MOC image covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.

  11. Thyroid storm due to head injury.

    PubMed

    Karaören, Gülşah Yılmaz; Sahin, Omer Torun; Erbesler, Zeynel Abidin; Bakan, Nurten

    2014-07-01

    In this case report, we would like to present a 36-year-old male patient injured in a street fight without any disease previously known, who was accepted to our intensive care unit with the preliminary diagnoses of minimal cerebral contusion and aspiration pneumonia however by the physical examination, clinical and laboratory findings, was diagnosed as thyroid storm due to trauma. In the current literature, only a few cases reported showing thyroid storm-induced by trauma, and we would like to present the clinical features and management of this life-threatening endocrinological emergency. PMID:25135028

  12. Volumetric Semantic Segmentation using Pyramid Context Features

    PubMed Central

    Barron, Jonathan T.; Arbeláez, Pablo; Keränen, Soile V. E.; Biggin, Mark D.; Knowles, David W.; Malik, Jitendra

    2015-01-01

    We present an algorithm for the per-voxel semantic segmentation of a three-dimensional volume. At the core of our algorithm is a novel “pyramid context” feature, a descriptive representation designed such that exact per-voxel linear classification can be made extremely efficient. This feature not only allows for efficient semantic segmentation but enables other aspects of our algorithm, such as novel learned features and a stacked architecture that can reason about self-consistency. We demonstrate our technique on 3D fluorescence microscopy data of Drosophila embryos for which we are able to produce extremely accurate semantic segmentations in a matter of minutes, and for which other algorithms fail due to the size and high-dimensionality of the data, or due to the difficulty of the task. PMID:26029008

  13. Dynamic absorption coefficients of CAR and non-CAR resists at EUV

    NASA Astrophysics Data System (ADS)

    Fallica, Roberto; Stowers, Jason K.; Grenville, Andrew; Frommhold, Andreas; Robinson, Alex P. G.; Ekinci, Yasin

    2016-03-01

    The dynamic absorption coefficients of several CAR and non-CAR EUV photoresists are measured experimentally using a specifically developed setup in transmission mode at the XIL beamline of the Swiss Light Source. The absorption coefficient α and the Dill parameters ABC were measured with unprecedented accuracy. In general the α of resists match very closely with the theoretical value calculated from elemental densities and absorption coefficients, whereas exceptions are observed. In addition, through the direct measurements of the absorption coefficients and dose-to-clear values, we introduce a new figure of merit called Chemical Sensitivity to account for all the post-absorption chemical reaction ongoing in the resist, which is also predicts a quantitative clearing volume, and respectively clearing radius, due to the photon absorption in the resist. These parameters may help in deeper insight into the underlying mechanisms of EUV concept of clearing volume and clearing radius are then defined and quantitatively calculated.

  14. X-Ray Absorption Spectroscopy Of Thin Foils Irradiated By An Ultra-short Laser Pulse

    SciTech Connect

    Renaudin, P.; Blancard, C.; Cosse, P.; Faussurier, G.; Lecherbourg, L.; Audebert, P.; Bastiani-Ceccotti, S.; Geindre, J.-P.; Shepherd, R.

    2007-08-02

    Point-projection K-shell absorption spectroscopy has been used to measure absorption spectra of transient plasma created by an ultra-short laser pulse. The 1s-2p and 1s-3p absorption lines of weakly ionized aluminum and the 2p-3d absorption lines of bromine were measured over an extended range of densities in a low-temperature regime. Independent plasma characterization was obtained using frequency domain interferometry diagnostic (FDI) that allows the interpretation of the absorption spectra in terms of spectral opacities. Assuming local thermodynamic equilibrium, spectral opacity calculations have been performed using the density and temperature inferred from the FDI diagnostic to compare to the measured absorption spectra. A good agreement is obtained when non-equilibrium effects due to non-stationary atomic physics are negligible at the x-ray probe time.

  15. X-Ray Absorption Spectroscopy Of Thin Foils Irradiated By An Ultra-short Laser Pulse

    NASA Astrophysics Data System (ADS)

    Renaudin, P.; Lecherbourg, L.; Blancard, C.; Cossé, P.; Faussurier, G.; Audebert, P.; Bastiani-Ceccotti, S.; Geindre, J.-P.; Shepherd, R.

    2007-08-01

    Point-projection K-shell absorption spectroscopy has been used to measure absorption spectra of transient plasma created by an ultra-short laser pulse. The 1s-2p and 1s-3p absorption lines of weakly ionized aluminum and the 2p-3d absorption lines of bromine were measured over an extended range of densities in a low-temperature regime. Independent plasma characterization was obtained using frequency domain interferometry diagnostic (FDI) that allows the interpretation of the absorption spectra in terms of spectral opacities. Assuming local thermodynamic equilibrium, spectral opacity calculations have been performed using the density and temperature inferred from the FDI diagnostic to compare to the measured absorption spectra. A good agreement is obtained when non-equilibrium effects due to non-stationary atomic physics are negligible at the x-ray probe time.

  16. Ultrasensitive optical absorption in graphene based on bound states in the continuum

    PubMed Central

    Zhang, Mingda; Zhang, Xiangdong

    2015-01-01

    We have designed a sphere-graphene-slab structure so that the electromagnetic wave can be well confined in the graphene due to the formation of a bound state in a continuum (BIC) of radiation modes. Based on such a bound state, we have realized strong optical absorption in the monolayer graphene. Such a strong optical absorption exhibits many advantages. It is ultrasensitive to the wavelength because the Q factor of the absorption peak can be more than 2000. By taking suitable BICs, the selective absorption for S and P waves has not only been realized, but also all-angle absorption for the S and P waves at the same time has been demonstrated. We have also found that ultrasensitive strong absorptions can appear at any wavelength from mid-infrared to far-infrared band. These phenomena are very beneficial to biosensing, perfect filters and waveguides. PMID:25652437

  17. High-resolution continuum source electrothermal atomic absorption spectrometry — An analytical and diagnostic tool for trace analysis

    NASA Astrophysics Data System (ADS)

    Welz, Bernhard; Borges, Daniel L. G.; Lepri, Fábio G.; Vale, Maria Goreti R.; Heitmann, Uwe

    2007-09-01

    The literature about applications of high-resolution continuum source atomic absorption spectrometry (HR-CS AAS) with electrothermal atomization is reviewed. The historic development of HR-CS AAS is briefly summarized and the main advantages of this technique, mainly the 'visibility' of the spectral environment around the analytical line at high resolution and the unequaled simultaneous background correction are discussed. Simultaneous multielement CS AAS has been realized only in a very limited number of cases. The direct analysis of solid samples appears to have gained a lot from the special features of HR-CS AAS, and the examples from the literature suggest that calibration can be carried out against aqueous standards. Low-temperature losses of nickel and vanadyl porphyrins could be detected and avoided in the analysis of crude oil due to the superior background correction system. The visibility of the spectral environment around the analytical line revealed that the absorbance signal measured for phosphorus at the 213.6 nm non-resonance line without a modifier is mostly due to the PO molecule, and not to atomic phosphorus. The future possibility to apply high-resolution continuum source molecular absorption for the determination of non-metals is discussed.

  18. The circumstellar nature of the metallic features in a hot DA white dwarf

    NASA Technical Reports Server (NTRS)

    Holberg, J. B.; Bruhweiler, F. C.; Andersen, J.

    1995-01-01

    A new co-added IUE echelle spectrum of the bright DA white dwarf CD -38 deg 10980, together with a newly determined radial velocity for this star, indicate that the sharp lined Si and C absorption features seen in the UV are clearly circumstellar in origin. Absorption in both excited and ground state transitions occurs at a velocity displaced by -12.1 +/- 2.0 km.s with respect to the photospheric velocity. Weak features due to the Si IV doublet are seen at a velocity intermediate between that of the circumstellar features and the photosphere. First time estimates of column densities for excited and ground states of C II, Si II, and Si III are derived. These quantities are used with electron density estimates derived from these species to determine the location and physical conditions of the circumstellar gas in the vicinity of CD -38 deg 10980. If collisional excitation alone is responsible for the excited levels of Si III observed in CD -38 deg 10980, then electron densities in the circumstellar gas must exceed 10(exp 9)/cu cm. Substantially lower electron densities are possible if the circumstellar gas is located near enough to the star so that photoexcitation is the dominant process responsible for the excited lines seen in the UV. Strong limits are placed on the photospheric abundance of Si and C in the star itself. These limits are in sharp contrast to the theoretical predictions of radiative levitation in which Si, but not C, is expected in the photosphere of a white dwarf such as CD -38 deg 10980. The interstellar line of sight to CD -38 deg 10980 is also investigated.

  19. Characterization of hydrophobic nanoporous particle liquids for energy absorption

    NASA Astrophysics Data System (ADS)

    Hsu, Yi; Liu, Yingtao

    2016-04-01

    Recently, the development of hydrophobic nanoporous technologies has drawn increased attention, especially for the applications of energy absorption and impact protection. Although significant amount of research has been conducted to synthesis and characterize materials to protect structures from impact damage, the tradition methods focused on converting kinetic energy to other forms, such as heat and cell buckling. Due to their high energy absorption efficiency, hydrophobic nanoporous particle liquids (NPLs) are one of the most attractive impact mitigation materials. During impact, such particles directly trap liquid molecules inside the non-wetting surface of nanopores in the particles. The captured impact energy is simply stored temporarily and isolated from the original energy transmission path. In this paper we will investigate the energy absorption efficiency of combinations of silica nanoporous particles and with multiple liquids. Inorganic particles, such as nanoporous silica, are characterized using scanning electron microscopy. Small molecule promoters, such as methanol and ethanol, are introduced to the prepared NPLs. Their effects on the energy absorption efficiency are studied in this paper. NPLs are prepared by dispersing the studied materials in deionized water. Energy absorption efficiency of these liquids are experimentally characterized using an Instron mechanical testing frame and in-house develop stainless steel hydraulic cylinder system.

  20. Development of an Ionic-Liquid Absorption Heat Pump

    SciTech Connect

    Holcomb, Don

    2011-03-29

    Solar Fueled Products (SFP) is developing an innovative ionic-liquid absorption heat pump (ILAHP). The development of an ILAHP is extremely significant, as it could result in annual savings of more than 190 billion kW h of electrical energy and $19 billion. This absorption cooler uses about 75 percent less electricity than conventional cooling and heating units. The ILAHP also has significant environmental sustainability benefits, due to reduced CO2 emissions. Phase I established the feasibility and showed the economic viability of an ILAHP with these key accomplishments: • Used the breakthrough capabilities provided by ionic liquids which overcome the key difficulties of the common absorption coolers. • Showed that the theoretical thermodynamic performance of an ILAHP is similar to existing absorption-cooling systems. • Established that the half-effect absorption cycle reduces the peak generator temperature, improving collector efficiency and reducing collector area. • Component testing demonstrated that the most critical components, absorber and generator, operate well with conventional heat exchangers. • Showed the economic viability of an ILAHP. The significant energy savings, sustainability benefits, and economic viability are compelling reasons to continue the ILAHP development.