Science.gov

Sample records for cold clumpy absorbers

  1. Clumpy cold dark matter

    NASA Technical Reports Server (NTRS)

    Silk, Joseph; Stebbins, Albert

    1993-01-01

    A study is conducted of cold dark matter (CDM) models in which clumpiness will inhere, using cosmic strings and textures suited to galaxy formation. CDM clumps of 10 million solar mass/cu pc density are generated at about z(eq) redshift, with a sizable fraction surviving. Observable implications encompass dark matter cores in globular clusters and in galactic nuclei. Results from terrestrial dark matter detection experiments may be affected by clumpiness in the Galactic halo.

  2. Cold, clumpy accretion onto an active supermassive black hole.

    PubMed

    Tremblay, Grant R; Oonk, J B Raymond; Combes, Françoise; Salomé, Philippe; O'Dea, Christopher P; Baum, Stefi A; Voit, G Mark; Donahue, Megan; McNamara, Brian R; Davis, Timothy A; McDonald, Michael A; Edge, Alastair C; Clarke, Tracy E; Galván-Madrid, Roberto; Bremer, Malcolm N; Edwards, Louise O V; Fabian, Andrew C; Hamer, Stephen; Li, Yuan; Maury, Anaëlle; Russell, Helen R; Quillen, Alice C; Urry, C Megan; Sanders, Jeremy S; Wise, Michael W

    2016-06-09

    Supermassive black holes in galaxy centres can grow by the accretion of gas, liberating energy that might regulate star formation on galaxy-wide scales. The nature of the gaseous fuel reservoirs that power black hole growth is nevertheless largely unconstrained by observations, and is instead routinely simplified as a smooth, spherical inflow of very hot gas. Recent theory and simulations instead predict that accretion can be dominated by a stochastic, clumpy distribution of very cold molecular clouds--a departure from the 'hot mode' accretion model--although unambiguous observational support for this prediction remains elusive. Here we report observations that reveal a cold, clumpy accretion flow towards a supermassive black hole fuel reservoir in the nucleus of the Abell 2597 Brightest Cluster Galaxy (BCG), a nearby (redshift z = 0.0821) giant elliptical galaxy surrounded by a dense halo of hot plasma. Under the right conditions, thermal instabilities produce a rain of cold clouds that fall towards the galaxy's centre, sustaining star formation amid a kiloparsec-scale molecular nebula that is found at its core. The observations show that these cold clouds also fuel black hole accretion, revealing 'shadows' cast by the molecular clouds as they move inward at about 300 kilometres per second towards the active supermassive black hole, which serves as a bright backlight. Corroborating evidence from prior observations of warmer atomic gas at extremely high spatial resolution, along with simple arguments based on geometry and probability, indicate that these clouds are within the innermost hundred parsecs of the black hole, and falling closer towards it.

  3. Cold, clumpy accretion onto an active supermassive black hole

    NASA Astrophysics Data System (ADS)

    Tremblay, Grant R.; Oonk, J. B. Raymond; Combes, Françoise; Salomé, Philippe; O'Dea, Christopher P.; Baum, Stefi A.; Voit, G. Mark; Donahue, Megan; McNamara, Brian R.; Davis, Timothy A.; McDonald, Michael A.; Edge, Alastair C.; Clarke, Tracy E.; Galván-Madrid, Roberto; Bremer, Malcolm N.; Edwards, Louise O. V.; Fabian, Andrew C.; Hamer, Stephen; Li, Yuan; Maury, Anaëlle; Russell, Helen R.; Quillen, Alice C.; Urry, C. Megan; Sanders, Jeremy S.; Wise, Michael W.

    2016-06-01

    Supermassive black holes in galaxy centres can grow by the accretion of gas, liberating energy that might regulate star formation on galaxy-wide scales. The nature of the gaseous fuel reservoirs that power black hole growth is nevertheless largely unconstrained by observations, and is instead routinely simplified as a smooth, spherical inflow of very hot gas. Recent theory and simulations instead predict that accretion can be dominated by a stochastic, clumpy distribution of very cold molecular clouds—a departure from the ‘hot mode’ accretion model—although unambiguous observational support for this prediction remains elusive. Here we report observations that reveal a cold, clumpy accretion flow towards a supermassive black hole fuel reservoir in the nucleus of the Abell 2597 Brightest Cluster Galaxy (BCG), a nearby (redshift z = 0.0821) giant elliptical galaxy surrounded by a dense halo of hot plasma. Under the right conditions, thermal instabilities produce a rain of cold clouds that fall towards the galaxy’s centre, sustaining star formation amid a kiloparsec-scale molecular nebula that is found at its core. The observations show that these cold clouds also fuel black hole accretion, revealing ‘shadows’ cast by the molecular clouds as they move inward at about 300 kilometres per second towards the active supermassive black hole, which serves as a bright backlight. Corroborating evidence from prior observations of warmer atomic gas at extremely high spatial resolution, along with simple arguments based on geometry and probability, indicate that these clouds are within the innermost hundred parsecs of the black hole, and falling closer towards it.

  4. CLUMPY STREAMS FROM CLUMPY HALOS: DETECTING MISSING SATELLITES WITH COLD STELLAR STRUCTURES

    SciTech Connect

    Yoon, Joo Heon; Johnston, Kathryn V.; Hogg, David W.

    2011-04-10

    Dynamically cold stellar streams are ideal probes of the gravitational field of the Milky Way. This paper re-examines the question of how such streams might be used to test for the presence of {sup m}issing satellites{sup -}the many thousands of dark-matter subhalos with masses 10{sup 5}-10{sup 7} M{sub sun} which are seen to orbit within Galactic-scale dark-matter halos in simulations of structure formation in {Lambda}CDM cosmologies. Analytical estimates of the frequency and energy scales of stream encounters indicate that these missing satellites should have a negligible effect on hot debris structures, such as the tails from the Sagittarius dwarf galaxy. However, long cold streams, such as the structure known as GD1 or those from the globular cluster Palomar 5 (Pal 5), are expected to suffer many tens of direct impacts from missing satellites during their lifetimes. Numerical experiments confirm that these impacts create gaps in the debris' orbital energy distribution, which will evolve into degree- and sub-degree-scale fluctuations in surface density over the age of the debris. Maps of Pal 5's own stream contain surface density fluctuations on these scales. The presence and frequency of these inhomogeneities suggests the existence of a population of missing satellites in numbers predicted in the standard {Lambda}CDM cosmologies.

  5. A submillimeter galaxy illuminating its circumgalactic medium: Lyα scattering in a cold, clumpy outflow

    SciTech Connect

    Geach, J. E.; Coppin, K. E. K.; Smith, D. J. B.; Bower, R. G.; Alexander, D. M.; Swinbank, A. M.; Blain, A. W.; Bremer, M. N.; Chapin, E. L.; Chapman, S. C.; Clements, D. L.; Dunlop, J. S.; Koprowski, M. P.; Michałowski, M. J.; Farrah, D.; Jenness, T.; Robson, E. I.; Scott, D.; Spaans, M.; Van der Werf, P.

    2014-09-20

    We report the detection at 850 μm of the central source in SSA22-LAB1, the archetypal 'Lyman-α Blob' (LAB), a 100 kpc scale radio-quiet emission-line nebula at z = 3.1. The flux density of the source, S {sub 850} = 4.6 ± 1.1 mJy, implies the presence of a galaxy or group of galaxies with a total luminosity of L {sub IR} ≈ 10{sup 12} L {sub ☉}. The position of an active source at the center of a ∼50 kpc radius ring of linearly polarized Lyα emission detected by Hayes et al. suggests that the central source is leaking Lyα photons preferentially in the plane of the sky, which undergo scattering in H I clouds at a large galactocentric radius. The Lyα morphology around the submillimeter detection is reminiscent of a biconical outflow, and the average Lyα line profiles of the two 'lobes' are dominated by a red peak, which is expected for a resonant line emerging from a medium with a bulk velocity gradient that is outflowing relative to the line center. Taken together, these observations provide compelling evidence that the central active galaxy (or galaxies) is responsible for a large fraction of the extended Lyα emission and morphology. Less clear is the history of the cold gas in the circumgalactic medium being traced by Lyα: is it mainly pristine material accreting into the halo that has not yet been processed through an interstellar medium (ISM), now being blown back as it encounters an outflow, or does it mainly comprise gas that has been swept-up within the ISM and expelled from the galaxy?.

  6. NEARBY CLUMPY, GAS RICH, STAR-FORMING GALAXIES: LOCAL ANALOGS OF HIGH-REDSHIFT CLUMPY GALAXIES

    SciTech Connect

    Garland, C. A.; Pisano, D. J.; Rabidoux, K.; Low, M.-M. Mac; Kreckel, K.; Guzmán, R. E-mail: djpisano@mail.wvu.edu E-mail: mordecai@amnh.org E-mail: guzman@astro.ufl.edu

    2015-07-10

    Luminous compact blue galaxies (LCBGs) have enhanced star formation rates (SFRs) and compact morphologies. We combine Sloan Digital Sky Survey data with H i data of 29 LCBGs at redshift z ∼ 0 to understand their nature. We find that local LCBGs have high atomic gas fractions (∼50%) and SFRs per stellar mass consistent with some high-redshift star-forming galaxies (SFGs). Many local LCBGs also have clumpy morphologies, with clumps distributed across their disks. Although rare, these galaxies appear to be similar to the clumpy SFGs commonly observed at z ∼ 1–3. Local LCBGs separate into three groups: (1) interacting galaxies (∼20%); (2) clumpy spirals (∼40%); and (3) non-clumpy, non-spirals with regular shapes and smaller effective radii and stellar masses (∼40%). It seems that the method of building up a high gas fraction, which then triggers star formation, is not the same for all local LCBGs. This may lead to a dichotomy in galaxy characteristics. We consider possible gas delivery scenarios and suggest that clumpy spirals, preferentially located in clusters and with companions, are smoothly accreting gas from tidally disrupted companions and/or intracluster gas enriched by stripped satellites. Conversely, as non-clumpy galaxies are preferentially located in the field and tend to be isolated, we suggest clumpy, cold streams, which destroy galaxy disks and prevent clump formation, as a likely gas delivery mechanism for these systems. Other possibilities include smooth cold streams, a series of minor mergers, or major interactions.

  7. The discovery of large amounts of cold, X-ray absorbing matter in cooling flows

    NASA Technical Reports Server (NTRS)

    White, D. A.; Fabian, A. C.; Johnstone, R. M.; Mushotzky, R. F.; Arnaud, K. A.

    1991-01-01

    The discovery of significant excess absorption in the X-ray spectra of 12 clusters of galaxies is reported. The spectra also require a cooling-flow component, which confirms the results of imaging studies of the clusters showing the strongly peaked emission characteristic of cooling flows. The total mass of absorbing gas is determined on the assumption that it is distributed through the cooling flow region and has cosmic abundance. It is shown that the gas is most likely in the form of small cold clouds. The excess absorption is interpreted as being due to photoelectric absorption in cold gas clouds distributed through the cooling flows.

  8. Large flux change due to the intervening cold absorbers in NGC 3516

    NASA Astrophysics Data System (ADS)

    Nogami, K.; Negoro, H.; Hong, S.; Mihara, T.

    2004-06-01

    NGC3516 in the low flux state shows a flat energy spectrum (photon index ~1) and an intense narrow iron line. Such spectra are also observed in other Seyfert galaxies, and a broad bump structure around 6 keV above the 'flat' power-law spectrum has been interpreted as the gravitationally red-shifted iron line, disk reflection, or cold and/or warm absorbers. However, six years if BeppoSAX observations, including our latest three ones in 2001, clearly demonstrate that energy spectra above 20 keV always exhibit steep power-laws with photon indices ~2, and the flux changes only by a factor of 2, while the soft X-ray flux by a factor of ~10. From this fact, using BeppoSAX and ASCA data, we have concluded that the flat spectrum results from reprocessed, and partially covered power-laws with Γ~1.8 by warm matter nearby the central source and a cold absorber moved in the line of sight, respectively, and that the broad iron line and disk reflection components are less significant than one ever thought. Thus, the long-term spectral variations can be considered by intervening absorbers rather than changes in the accretion rate.

  9. High-z QSO Absorption Systems: Metal-Poor Cold Flows and Mg II Absorber Host Galaxies

    NASA Astrophysics Data System (ADS)

    Cooper, Thomas; Simcoe, R. A.; Cooksey, K.; O'Meara, J.

    2014-01-01

    Cosmological simulations have suggested a new model for gas accretion in young galaxies, in which baryons flow into the star-forming disk along filamentary streams without shock heating at the dark matter halo virial radius. Observationally, these cold flows manifest as Lyman Limit Systems with low heavy element abundances. To search for cold flows in the early Universe, we have obtained echellette-resolution spectra of an HI-selected sample of LLS at z>3.5 from the Sloan Digital Sky Survey. The sightlines were selected to exhibit no heavy element absorption at the resolution afforded by SDSS, and the higher resolution data provides metallicity measurements precise enough to determine if they exhibit cold flow accretion characteristics. In a parallel program, we use the Magellan Telescopes and HST/WFC-3 to investigate the connection between Mg II absorbers and proximate galaxies at 3, extending fruitful studies of the circumgalactic medium to larger redshift.

  10. Clumpy and Extended Starbursts in the Brightest Unlensed Submillimeter Galaxies

    NASA Astrophysics Data System (ADS)

    Iono, Daisuke; Yun, Min S.; Aretxaga, Itziar; Hatsukade, Bunyo; Hughes, David; Ikarashi, Soh; Izumi, Takuma; Kawabe, Ryohei; Kohno, Kotaro; Lee, Minju; Matsuda, Yuichi; Nakanishi, Kouichiro; Saito, Toshiki; Tamura, Yoichi; Ueda, Junko; Umehata, Hideki; Wilson, Grant; Michiyama, Tomonari; Ando, Misaki

    2016-09-01

    The central structure in three of the brightest unlensed z = 3-4 submillimeter galaxies is investigated through 0.″015-0.″05 (120-360 pc) 860 μm continuum images obtained using the Atacama Large Millimeter/submillimeter Array (ALMA). The distribution in the central kiloparsec in AzTEC1 and AzTEC8 is extremely complex, and they are composed of multiple ˜200 pc clumps. AzTEC4 consists of two sources that are separated by ˜1.5 kpc, indicating a mid-stage merger. The peak star formation rate densities in the central clumps are ˜300-3000 M ⊙ yr-1 kpc-2, suggesting regions with extreme star formation near the Eddington limit. By comparing the flux obtained by ALMA and Submillimeter Array, we find that 68%-90% of the emission is extended (≳1 kpc) in AzTEC4 and 8. For AzTEC1, we identify at least 11 additional compact (˜200 pc) clumps in the extended 3-4 kpc region. Overall, the data presented here suggest that the luminosity surface densities observed at ≲150 pc scales are roughly similar to that observed in local ULIRGs, as in the eastern nucleus of Arp 220. Between 10% and 30% of the 860 μm continuum is concentrated in clumpy structures in the central kiloparsec, while the remaining flux is distributed over ≳1 kpc regions, some of which could also be clumpy. These sources can be explained by a rapid inflow of gas such as a merger of gas-rich galaxies, surrounded by extended and clumpy starbursts. However, the cold mode accretion model is not ruled out.

  11. Extinction and dust properties in a clumpy medium

    NASA Astrophysics Data System (ADS)

    Scicluna, P.; Siebenmorgen, R.

    2015-12-01

    The dust content of the universe is primarily explored via its interaction with stellar photons, which are absorbed or scattered by the dust, producing the effect known as interstellar extinction. However, owing to the physical extension of the observing beam, real observations may detect a significant number of dust-scattered photons. This may result in a change in the observed (or effective) extinction with a dependence on the spatial distribution of the dust and the spatial resolution of the instrument. We investigate the influence of clumpy dust distributions on the effective extinction toward both embedded sources and those seen through the diffuse interstellar medium (ISM). We use a Monte Carlo radiative transfer code to examine the effective extinction for various geometries. By varying the number, optical depth and volume-filling factor of clumps inside the model for spherical shells and the diffuse interstellar medium (ISM), we explore the evolution of the extinction curve and effective optical depth. Depending on the number of scattering events in the beam, the extinction curve is observed to steepen in homogeneous media and flatten in clumpy media. As a result, clumpy dust distributions are able to reproduce extinction curves with arbitrary RV,eff, the effective ratio of total-to-selective extinction. The flattening is also able to "wash out" the 2175 Å bump and results in a shift of the peak to shorter wavelengths. The mean RV,eff of a shell is shown to correlate with the optical depth of an individual clump and the wavelength at which a clump becomes optically thick. Similar behaviour is seen for edge-on discs or tori. However, at grazing inclinations the combination of extinction and strong forward scattering results in chaotic behaviour. Caution is therefore advised when attempting to measure extinction in AGN tori for example or toward SNIa or GRB afterglows. In face-on discs, the shape of the scattered continuum is observed to change significantly

  12. CLUMPY ACCRETION ONTO BLACK HOLES. I. CLUMPY-ADVECTION-DOMINATED ACCRETION FLOW STRUCTURE AND RADIATION

    SciTech Connect

    Wang Jianmin; Cheng Cheng; Li Yanrong

    2012-04-01

    We investigate the dynamics of clumps embedded in and confined by the advection-dominated accretion flows (ADAFs), in which collisions among the clumps are neglected. We start from the collisionless Boltzmann equation and assume that interaction between the clumps and the ADAF is responsible for transporting the angular momentum of clumps outward. The inner edge of the clumpy-ADAF is set to be the tidal radius of the clumps. We consider strong- and weak-coupling cases, in which the averaged properties of clumps follow the ADAF dynamics and are mainly determined by the black hole potential, respectively. We propose the analytical solution of the dynamics of clumps for the two cases. The velocity dispersion of clumps is one magnitude higher than the ADAF for the strong-coupling case. For the weak-coupling case, we find that the mean radial velocity of clumps is linearly proportional to the coefficient of the drag force. We show that the tidally disrupted clumps would lead to an accumulation of the debris to form a debris disk in the Shakura-Sunyaev regime. The entire hot ADAF will be efficiently cooled down by photons from the debris disk, giving rise to a collapse of the ADAF, and quench the clumpy accretion. Subsequently, evaporation of the collapsed ADAF drives resuscitate of a new clumpy-ADAF, resulting in an oscillation of the global clumpy-ADAF. Applications of the present model are briefly discussed to X-ray binaries, low ionization nuclear emission regions, and BL Lac objects.

  13. Clumpy Molecular Structures Revolving the B[e] Supergiant MWC 137

    NASA Astrophysics Data System (ADS)

    Kraus, M.; Cidale, L. S.; Liimets, T.; Cappa, C. E.; Duronea, N.; Gunawan, D. S.; Oksala, M. E.; Santander-García, M.; Arias, M. L.; Nickeler, D. H.; Maravelias, G.; Borges Fernandes, M.; Curé, M.

    2017-02-01

    The peculiar emission-line star MWC 137 with its extended optical nebula was recently classified as a B[e] supergiant. To study the spatial distribution of its circumstellar molecular gas on small and large scales, we obtained near-infrared and radio observations using SINFONI and APEX, respectively. We find that the hot CO gas is arranged in a moving clumpy ring and shell structures close to the star, while a cold CO envelope is encircling the borders of the optical nebula from South to West.

  14. Clumpy Galaxies in the Early Universe

    NASA Astrophysics Data System (ADS)

    Elmegreen, Debra Meloy

    2007-05-01

    High redshift galaxies larger than 10 pixels were observed with the HST ACS in the Ultra Deep Field and Tadpole galaxy field in order to determine their morphological classes and photometric properties. Over 1300 galaxies were studied; most are at redshifts 1 to 3, although several dozen Lyman Break Galaxies were observed at redshifts 4 and 5. Galaxy types include chains, clump-clusters, doubles, tadpoles, spirals, and ellipticals. Ordinary spiral and elliptical galaxies are rare in the early universe; clumpy galaxies dominate at fainter than magnitude 25. Face-on spirals are scarce at high z because of surface brightness selection effects. Chain galaxies and clump-cluster galaxies appear to be a single galaxy type viewed at different orientations; they have no bulges or exponential profiles. Spiral galaxies at high z have exponential profiles with scale lengths that average half that of local galaxies, implying that disks must grow from the inside out with time. Star-forming clusters in both clump-clusters and spirals have exponential radial distributions, suggesting that the clumps in clump-clusters will eventually disperse to form exponential disks. There is a nearly uniform fraction of barred galaxies with z, suggesting that bar dissolution is not a prominent occurrence. The appearance of blue clumpy bars suggests that bar formation sometimes occurs from gas-phase disk instabilities rather than stellar instabilities. Thirty percent of elliptical galaxies at high z contain blue clumps. The prominent star-forming clumps in clump clusters and ellipticals were compared with stellar evolution models to determine ages and masses; these regions are unlike star-forming regions in the local universe. They have ages less than 1 Gyr and contain one billion solar masses. They resemble isolated clumps in the UDF, suggesting accretion in a hierarchical build-up model.

  15. Parameters of type IIP SN 2012A and clumpiness effects

    NASA Astrophysics Data System (ADS)

    Utrobin, V. P.; Chugai, N. N.

    2015-03-01

    Context. The explosion energy and the ejecta mass of a type IIP supernova (SN IIP) derived from hydrodynamic simulations are principal parameters of the explosion theory. Few SNe IIP have been studied by hydrodynamic modeling so far, however. Some doubts exist about the reliability of the derived SN IIP parameters. Aims: We studied the well-observed type IIP SN 2012A with hydrodynamic modeling. We examined its early spectra for ejecta clumpiness. We also explored other observational effects of clumpiness. Methods: We determined the supernova parameters by means of standard hydrodynamic modeling. We used the early hydrogen Hα and Hβ lines as clumpiness diagnostics. We used a modified hydrodynamic code to study the clumpiness effect in the light curve and expansion kinematics. Results: We found that SN 20012A is the result of the explosion of a red supergiant with a radius of 715 ± 100 R⊙. The explosion energy is (5.25 ± 0.6) × 1050 erg, the ejecta mass is 13.1 ± 0.7 M⊙, and the total 56Ni mass is 0.012 ± 0.002 M⊙. The estimated mass of a progenitor, a main-sequence star, is 15 ± 1 M⊙. The Hα and Hβ lines in early spectra indicate that outer ejecta are clumpy. Hydrodynamic simulations show that the clumpiness modifies the early light curve and increases the maximum velocity of the outer layers. Conclusions: The pre-SN 2012A was a normal red supergiant with the progenitor mass of ≈ 15 M⊙. The outer layers of ejecta indicate the clumpy structure. The clumpiness of the external layers can increase the maximum expansion velocity.

  16. SPECTROPOLARIMETRIC SIGNATURES OF CLUMPY SUPERNOVA EJECTA

    SciTech Connect

    Hole, K. T.; Nordsieck, K. H.; Kasen, D.

    2010-09-10

    Polarization has been detected at early times for all types of supernovae (SNe), indicating that all such systems result from or quickly develop some form of asymmetry. In addition, the detection of strong line polarization in SNe is suggestive of chemical inhomogeneities ('clumps') in the layers above the photosphere, which may reflect hydrodynamical instabilities during the explosion. We have developed a fast, flexible, approximate semi-analytic code for modeling polarized line radiative transfer within three-dimensional inhomogeneous rapidly expanding atmospheres. Given a range of model parameters, the code generates random sets of clumps in the expanding ejecta and calculates the emergent line profile and Stokes parameters for each configuration. The ensemble of these configurations represents the effects both of various host geometries and of different viewing angles. We present results for the first part of our survey of model geometries, specifically the effects of the number and size of clumps (and the related effect of filling factor) on the emergent spectrum and Stokes parameters. Our simulations show that random clumpiness can produce line polarization in the range observed in SNe Ia, as well as the Q-U loops that are frequently seen in all SNe. We have also developed a method to connect the results of our simulations to robust observational parameters such as maximum polarization and polarized equivalent width in the line. Our models, in connection with spectropolarimetric observations, can constrain the three-dimensional structure of SN ejecta and offer important insight into the SN explosion physics and the nature of their progenitor systems.

  17. A DEEP SEARCH FOR FAINT GALAXIES ASSOCIATED WITH VERY LOW-REDSHIFT C IV ABSORBERS: A CASE WITH COLD-ACCRETION CHARACTERISTICS

    SciTech Connect

    Burchett, Joseph N.; Tripp, Todd M.; Werk, Jessica K.; Prochaska, J. Xavier; Ford, Amanda Brady; Davé, Romeel

    2013-12-20

    Studies of QSO absorber-galaxy connections are often hindered by inadequate information on whether faint/dwarf galaxies are located near the QSO sight lines. To investigate the contribution of faint galaxies to QSO absorber populations, we are conducting a deep galaxy redshift survey near low-z C IV absorbers. Here we report a blindly detected C IV absorption system (z {sub abs} = 0.00348) in the spectrum of PG1148+549 that appears to be associated either with an edge-on dwarf galaxy with an obvious disk (UGC 6894, z {sub gal} = 0.00283) at an impact parameter of ρ = 190 kpc or with a very faint dwarf irregular galaxy at ρ = 23 kpc, which is closer to the sightline but has a larger redshift difference (z {sub gal} = 0.00107, i.e., δv = 724 km s{sup –1}). We consider various gas/galaxy associations, including infall and outflows. Based on current theoretical models, we conclude that the absorber is most likely tracing (1) the remnants of an outflow from a previous epoch, a so-called {sup a}ncient outflow{sup ,} or (2) intergalactic gas accreting onto UGC 6894, ''cold mode'' accretion. The latter scenario is supported by H I synthesis imaging data that shows the rotation curve of the disk being codirectional with the velocity offset between UGC 6894 and the absorber, which is located almost directly along the major axis of the edge-on disk.

  18. Investigations of freezing and cold storage for the analysis of peatland dissolved organic carbon (DOC) and absorbance properties.

    PubMed

    Peacock, Mike; Freeman, Chris; Gauci, Vincent; Lebron, Inma; Evans, Chris D

    2015-07-01

    Although measured rates of biological degradation of DOC are typically low under dark conditions, it is assumed that water samples must be analysed soon after collection to provide an accurate measure of DOC concentration and UV-visible absorbance. To examine the impact of storage on DOC quality and quantity, we took water samples from an ombrotrophic peatland, and stored them in the dark at 4 °C for 138-1082 days. A median of 29% of DOC was lost during storage, but losses of absorbance at 254 nm were less. DOC loss followed a first-order exponential decay function, and was dependent on storage time. DOC half-life was calculated as 1253 days. Specific absorbance at 254 nm suggested that samples containing more aromatic DOC were more resistant to degradation, although time functioned as the primary control. Samples from two fens showed that loss of absorbance was greater at 400 nm rather than 254 nm, after 192 days storage, suggesting that non-aromatic DOC is preferentially degraded. These results suggest that samples can be stored for several months before losses of DOC become detectable, and that it is possible to back-calculate initial DOC concentrations in long-term stored samples based on known decay rates. Freeze/thaw experiments using samples from a range of peatlands suggested that DOC concentration was mostly unaffected by the process, but DOC increased 37% in one sample. Freezing had unpredictable and sometimes strong effects on absorbance, SUVA and E ratios, therefore freezing is not recommended as a method of preservation for these analyses.

  19. MASSIVE BLACK HOLE PAIRS IN CLUMPY, SELF-GRAVITATING CIRCUMNUCLEAR DISKS: STOCHASTIC ORBITAL DECAY

    SciTech Connect

    Fiacconi, Davide; Mayer, Lucio; Roškar, Rok; Colpi, Monica

    2013-11-01

    We study the dynamics of massive black hole pairs in clumpy gaseous circumnuclear disks. We track the orbital decay of the light, secondary black hole M {sub .2} orbiting around the more massive primary at the center of the disk, using N-body/smoothed particle hydrodynamic simulations. We find that the gravitational interaction of M {sub .2} with massive clumps M {sub cl} erratically perturbs the otherwise smooth orbital decay. In close encounters with massive clumps, gravitational slingshots can kick the secondary black hole out of the disk plane. The black hole moving on an inclined orbit then experiences the weaker dynamical friction of the stellar background, resulting in a longer orbital decay timescale. Interactions between clumps can also favor orbital decay when the black hole is captured by a massive clump that is segregating toward the center of the disk. The stochastic behavior of the black hole orbit emerges mainly when the ratio M {sub .2}/M {sub cl} falls below unity, with decay timescales ranging from ∼1 to ∼50 Myr. This suggests that describing the cold clumpy phase of the interstellar medium in self-consistent simulations of galaxy mergers, albeit so far neglected, is important to predict the black hole dynamics in galaxy merger remnants.

  20. Star formation and chemical abundances in clumpy irregular galaxies

    SciTech Connect

    Boesgaard, A.M.; Edwards, S.; Heidmann, J.

    1982-01-15

    Clumpy irregular galaxies consist of several bright clumps which are huge H II complexes (about 100 times brighter and more massive than 30 Doradus) and contain about 10/sup 5/ O and B stars. Image-tube spectrograms with 1--3 A resolution have been obtained of the brightest emission regions of three clumpy galaxies and one candidate clumpy galaxy with the Mauna Kea 2.24 m telescope. The electron temperatures were found to be in the range 7000--9000 K and electron densities a few hundred cm/sup 3/: quite typical for normal H II regions. The abundances of O, N. S in Mrk 432 are comparable to those in Orion, while the three clumpy galaxies are slightly deficient in O and S (by factors of 2 to 4) and N (by factors of 3 to 6). The galaxies appear to be normal (like Sc galaxies) in mass and composition. Supernovae remnants are indicated by the high (S II)/H..cap alpha.. ratio. Possible triggering mechanisms for the exceptional star formation activity are discussed.

  1. Competition drives clumpy species coexistence in estuarine phytoplankton.

    PubMed

    Segura, A M; Kruk, C; Calliari, D; García-Rodriguez, F; Conde, D; Widdicombe, C E; Fort, H

    2013-01-01

    Understanding the mechanisms that maintain biodiversity is a fundamental problem in ecology. Competition is thought to reduce diversity, but hundreds of microbial aquatic primary producers species coexist and compete for a few essential resources (e.g., nutrients and light). Here, we show that resource competition is a plausible mechanism for explaining clumpy distribution on individual species volume (a proxy for the niche) of estuarine phytoplankton communities ranging from North America to South America and Europe, supporting the Emergent Neutrality hypothesis. Furthermore, such a clumpy distribution was also observed throughout the Holocene in diatoms from a sediment core. A Lotka-Volterra competition model predicted position in the niche axis and functional affiliation of dominant species within and among clumps. Results support the coexistence of functionally equivalent species in ecosystems and indicate that resource competition may be a key process to shape the size structure of estuarine phytoplankton, which in turn drives ecosystem functioning.

  2. Kinematic imprint of clumpy disk formation on halo objects

    NASA Astrophysics Data System (ADS)

    Inoue, Shigeki

    2013-02-01

    Context. Clumpy disk galaxies in the distant universe, at redshift of z ≳ 1, have been observed to host several giant clumps in their disks. They are thought to correspond to early formative stages of disk galaxies. On the other hand, halo objects, such as old globular clusters and halo stars, are likely to consist of the oldest stars in a galaxy (age ≳ 10 Gyr), clumpy disk formation can thus be presumed to take place in a pre-existing halo system. Aims: Giant clumps orbit in the same direction in a premature disk and are so massive that they may be expected to interact gravitationally with halo objects and exercise influence on the kinematic state of the halo. Accordingly, I scrutinize the possibility that the clumps leave a kinematic imprint of the clumpy disk formation on a halo system. Methods: I perform a restricted N-body calculation with a toy model to study the kinematic influence on a halo by orbital motions of clumps and the dependence of the results on masses (mass loss), number, and orbital radii of the clumps. Results: I show that halo objects can catch clump motions and acquire disky rotation in a dynamical friction time scale of the clumps, ~0.5 Gyr. The influence of clumps is limited within a region around the disk, while the halo system shows vertical gradients of net rotation velocity and orbital eccentricity. The significance of the kinematic influence strongly depends on the clump masses; the lower limit of postulated clump mass would be ~5 × 108 M⊙. The result also depends on whether the clumps are subjected to rapid mass loss or not, which is an open question under debate in recent studies. The existence of such massive clumps is not unrealistic. I therefore suggest that the imprints of past clumpy disk formation could remain in current galactic halos.

  3. Synthetic absorption lines for a clumpy medium: a spectral signature for cloud acceleration in AGN?

    NASA Astrophysics Data System (ADS)

    Waters, Tim; Proga, Daniel; Dannen, Randall; Kallman, Timothy R.

    2017-01-01

    There is increasing evidence that the highly ionised multiphase components of AGN disc winds may be due to thermal instability. The ions responsible for forming the observed X-ray absorption lines may only exist in relatively cool clumps that can be identified with the so-called `warm absorbers'. Here we calculate synthetic absorption lines for such warm absorbers from first principles by combining 2D hydrodynamic solutions of a two-phase medium with a dense grid of photoionization models to determine the detailed ionization structure of the gas. Our calculations reveal that cloud disruption, which leads to a highly complicated velocity field (i.e. a clumpy flow), will only mildly affect line shapes and strengths when the warm gas becomes highly mixed but not depleted. Prior to complete disruption, clouds which are optically thin to the driving UV resonance lines will cause absorption at an increasingly blueshifted line of sight velocity as they are accelerated. This behavior will imprint an identifiable signature on the line profile if warm absorbers are enshrouded in an even broader absorption line produced by a high column of intercloud gas. Interestingly, we show that it is possible to develop a spectral diagnostic for cloud acceleration by differencing the absorption components of a doublet line, a result which can be qualitatively understood using a simple partial covering model. Our calculations also permit us to comment on the spectral differences between cloud disruption and ionization changes driven by flux variability. Notably, cloud disruption offers another possibility for explaining absorption line variability.

  4. Low Angular Momentum in Clumpy, Turbulent Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Obreschkow, Danail; Glazebrook, Karl; Bassett, Robert; Fisher, David B.; Abraham, Roberto G.; Wisnioski, Emily; Green, Andrew W.; McGregor, Peter J.; Damjanov, Ivana; Popping, Attila; Jørgensen, Inger

    2015-12-01

    We measure the stellar specific angular momentum {j}s={J}s/{M}s in four nearby (z ≈ 0.1) disk galaxies that have stellar masses {M}s near the break {M}s* of the galaxy mass function but look like typical star-forming disks at z ≈ 2 in terms of their low stability (Q ≈ 1), clumpiness, high ionized gas dispersion (40-50 {km} {{{s}}}-1), high molecular gas fraction (20%-30%), and rapid star formation (˜ 20{M}⊙ {{yr}}-1). Combining high-resolution (Keck-OSIRIS) and large-radius (Gemini-GMOS) spectroscopic maps, only available at low z, we discover that these targets have ˜ 3 times less stellar angular momentum than typical local spiral galaxies of equal stellar mass and bulge fraction. Theoretical considerations show that this deficiency in angular momentum is the main cause of their low stability, while the high gas fraction plays a complementary role. Interestingly, the low {j}s values of our targets are similar to those expected in the {M}s* population at higher z from the approximate theoretical scaling {j}s\\propto {(1+z)}-1/2 at fixed {M}s. This suggests that a change in angular momentum, driven by cosmic expansion, is the main cause for the remarkable difference between clumpy {M}s* disks at high z (which likely evolve into early-type galaxies) and mass-matched local spirals.

  5. Probing the clumpy winds of giant stars with high mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Grinberg, Victoria; Hell, Natalie; Hirsch, Maria; Garcia, Javier; Huenemoerder, David; Leutenegger, Maurice A.; Nowak, Michael; Pottschmidt, Katja; Schulz, Norbert S.; Sundqvists, Jon O.; Townsend, Richard D.; Wilms, Joern

    2016-04-01

    Line-driven winds from early type stars are structured, with small, overdense clumps embedded in tenuous hot gas. High mass X-ray binaries (HMXBs), systems where a neutron star or a black hole accretes from the line-driven stellar wind of an O/B-type companion, are ideal for studying such winds: the wind drives the accretion onto the compact object and thus the X-ray production. The radiation from close to the compact object is quasi-pointlike and effectively X-rays the wind.We used RXTE and Chandra-HETG observations of two of the brightest HMXBs, Cyg X-1 and Vela X-1, to decipher their wind structure. In Cyg X-1, we show that the orbital variability of absorption can be only explained by a clumpy wind model and constrain the porosity of the wind as well as the onion-like structure of the clumps. In Vela X-1 we show, using the newest reference energies for low ionization Si-lines obtained with LLNL’s EBIT-I, that the ionized phase of the circumstellar medium and the cold clumps have different velocities.

  6. A Chandra view of the clumpy reflector at the heart of the Circinus galaxy

    NASA Astrophysics Data System (ADS)

    Marinucci, A.; Miniutti, G.; Bianchi, S.; Matt, G.; Risaliti, G.

    2013-12-01

    We present a spectral and imaging analysis of the X-ray reflecting structure at the heart of the Circinus galaxy, investigating the innermost regions surrounding the central black hole. By studying an archival 200 ks Chandra Advanced CCD Imaging Spectrometer-S observation, we are able to image the extended clumpy structure responsible for both cold reflection of the primary radiation and neutral iron Kα line emission. We measure an excess of the equivalent width of the iron Kα line which follows an axisymmetric geometry around the nucleus on a hundred pc scale. Spectra extracted from different regions confirm a scenario in which the dominant mechanism is the reflection of the nuclear radiation from Compton-thick gas. Significant differences in the equivalent width of the iron Kα emission line (up to a factor of 2) are found. It is argued that these differences are due to different scattering angles with respect to the line of sight rather than to different iron abundances.

  7. MIXING OF CLUMPY SUPERNOVA EJECTA INTO MOLECULAR CLOUDS

    SciTech Connect

    Pan Liubin; Desch, Steven J.; Scannapieco, Evan; Timmes, F. X.

    2012-09-01

    Several lines of evidence, from isotopic analyses of meteorites to studies of the Sun's elemental and isotopic composition, indicate that the solar system was contaminated early in its evolution by ejecta from a nearby supernova. Previous models have invoked supernova material being injected into an extant protoplanetary disk, or isotropically expanding ejecta sweeping over a distant (>10 pc) cloud core, simultaneously enriching it and triggering its collapse. Here, we consider a new astrophysical setting: the injection of clumpy supernova ejecta, as observed in the Cassiopeia A supernova remnant, into the molecular gas at the periphery of an H II region created by the supernova's progenitor star. To track these interactions, we have conducted a suite of high-resolution (1500{sup 3} effective) three-dimensional numerical hydrodynamic simulations that follow the evolution of individual clumps as they move into molecular gas. Even at these high resolutions, our simulations do not quite achieve numerical convergence, due to the challenge of properly resolving the small-scale mixing of ejecta and molecular gas, although they do allow some robust conclusions to be drawn. Isotropically exploding ejecta do not penetrate into the molecular cloud or mix with it, but, if cooling is properly accounted for, clumpy ejecta penetrate to distances {approx}10{sup 18} cm and mix effectively with large regions of star-forming molecular gas. In fact, the {approx}2 M{sub Sun} of high-metallicity ejecta from a single core-collapse supernova is likely to mix with {approx}2 Multiplication-Sign 10{sup 4} M{sub Sun} of molecular gas material as it is collapsing. Thus, all stars forming late ( Almost-Equal-To 5 Myr) in the evolution of an H II region may be contaminated by supernova ejecta at the level {approx}10{sup -4}. This level of contamination is consistent with the abundances of short-lived radionuclides and possibly some stable isotopic shifts in the early solar system and is

  8. First X-ray Statistical Tests for Clumpy-Torus Models: Constraints from RXTEmonitoring of Seyfert AGN

    NASA Astrophysics Data System (ADS)

    Markowitz, Alex; Krumpe, Mirko; Nikutta, R.

    2016-06-01

    In two papers (Markowitz, Krumpe, & Nikutta 2014, and Nikutta et al., in prep.), we derive the first X-ray statistical constraints for clumpy-torus models in Seyfert AGN by quantifying multi-timescale variability in line of-sight X-ray absorbing gas as a function of optical classification.We systematically search for discrete absorption events in the vast archive of RXTE monitoring of 55 nearby type Is and Compton-thin type IIs. We are sensitive to discrete absorption events due to clouds of full-covering, neutral/mildly ionized gas transiting the line of sight. Our results apply to both dusty and non-dusty clumpy media, and probe model parameter space complementary to that for eclipses observed with XMM-Newton, Suzaku, and Chandra.We detect twelve eclipse events in eight Seyferts, roughly tripling the number previously published from this archive. Event durations span hours to years. Most of our detected clouds are Compton-thin, and most clouds' distances from the black hole are inferred to be commensurate with the outer portions of the BLR or the inner regions of infrared-emitting dusty tori.We present the density profiles of the highest-quality eclipse events; the column density profile for an eclipsing cloud in NGC 3783 is doubly spiked, possibly indicating a cloud that is being tidallysheared. We discuss implications for cloud distributions in the context of clumpy-torus models. We calculate eclipse probabilities for orientation-dependent Type I/II unification schemes.We present constraints on cloud sizes, stability, and radial distribution. We infer that clouds' small angular sizes as seen from the SMBH imply 107 clouds required across the BLR + torus. Cloud size is roughly proportional to distance from the black hole, hinting at the formation processes (e.g., disk fragmentation). All observed clouds are sub-critical with respect to tidal disruption; self-gravity alone cannot contain them. External forces, such as magnetic fields or ambient pressure, are

  9. First X-ray Statistical Tests for Clumpy Torii Models: Constraints from RXTE monitoring of Seyfert AGN

    NASA Astrophysics Data System (ADS)

    Markowitz, A.

    2015-09-01

    We summarize two papers providing the first X-ray-derived statistical constraints for both clumpy-torus model parameters and cloud ensemble properties. In Markowitz, Krumpe, & Nikutta (2014), we explored multi-timescale variability in line-of-sight X-ray absorbing gas as a function of optical classification. We examined 55 Seyferts monitored with the Rossi X-ray Timing Explorer, and found in 8 objects a total of 12 eclipses, with durations between hours and years. Most clouds are commensurate with the outer portions of the BLR, or the inner regions of infrared-emitting dusty tori. The detection of eclipses in type Is disfavors sharp-edged tori. We provide probabilities to observe a source undergoing an absorption event for both type Is and IIs, yielding constraints in [N_0, sigma, i] parameter space. In Nikutta et al., in prep., we infer that the small cloud angular sizes, as seen from the SMBH, imply the presence of >10^7 clouds in BLR+torus to explain observed covering factors. Cloud size is roughly proportional to distance from the SMBH, hinting at the formation processes (e.g. disk fragmentation). All observed clouds are sub-critical with respect to tidal disruption; self-gravity alone cannot contain them. External forces (e.g. magnetic fields, ambient pressure) are needed to contain them, or otherwise the clouds must be short-lived. Finally, we infer that the radial cloud density distribution behaves as 1/r^{0.7}, compatible with VLTI observations. Our results span both dusty and non-dusty clumpy media, and probe model parameter space complementary to that for short-term eclipses observed with XMM-Newton, Suzaku, and Chandra.

  10. Black hole growth and AGN feedback under clumpy accretion

    NASA Astrophysics Data System (ADS)

    DeGraf, C.; Dekel, A.; Gabor, J.; Bournaud, F.

    2017-04-01

    High-resolution simulations of supermassive black holes in isolated galaxies have suggested the importance of short (∼10 Myr) episodes of rapid accretion caused by interactions between the black hole and massive dense clouds within the host. Accretion of such clouds could potentially provide the dominant source for black hole growth in high-z galaxies, but it remains unresolved in cosmological simulations. Using a stochastic subgrid model calibrated by high-resolution isolated galaxy simulations, we investigate the impact that variability in black hole accretion rates has on black hole growth and the evolution of the host galaxy. We find this clumpy accretion to more efficiently fuel high-redshift black hole growth. This increased mass allows for more rapid accretion even in the absence of high-density clumps, compounding the effect and resulting in substantially faster overall black hole growth. This increased growth allows the black hole to efficiently evacuate gas from the central region of the galaxy, driving strong winds up to ∼2500 km s-1, producing outflows ∼10 × stronger than the smooth accretion case, suppressing the inflow of gas on to the host galaxy, and suppressing the star formation within the galaxy by as much as a factor of 2. This suggests that the proper incorporation of variability is a key factor in the co-evolution between black holes and their hosts.

  11. CLUMPY GALAXIES IN CANDELS. I. THE DEFINITION OF UV CLUMPS AND THE FRACTION OF CLUMPY GALAXIES AT 0.5 < z < 3

    SciTech Connect

    Guo, Yicheng; Koo, David C.; Barro, Guillermo; Faber, Sandra M.; Fang, Jerome J.; Bell, Eric F.; Conselice, Christopher J.; Giavalisco, Mauro; Lu, Yu; Mandelker, Nir; Dekel, Avishai; McIntosh, Daniel M.; Primack, Joel R.; Ceverino, Daniel; and others

    2015-02-10

    Although giant clumps of stars are thought to be crucial to galaxy formation and evolution, the most basic demographics of clumps are still uncertain, mainly because the definition of clumps has not been thoroughly discussed. In this paper, we carry out a study of the basic demographics of clumps in star-forming galaxies at 0.5 < z < 3, using our proposed physical definition that UV-bright clumps are discrete star-forming regions that individually contribute more than 8% of the rest-frame UV light of their galaxies. Clumps defined this way are significantly brighter than the H II regions of nearby large spiral galaxies, either individually or blended, when physical spatial resolution and cosmological dimming are considered. Under this definition, we measure the fraction of star-forming galaxies that have at least one off-center clump (f {sub clumpy}) and the contributions of clumps to the rest-frame UV light and star formation rate (SFR) of star-forming galaxies in the CANDELS/GOODS-S and UDS fields, where our mass-complete sample consists of 3239 galaxies with axial ratio q > 0.5. The redshift evolution of f {sub clumpy} changes with the stellar mass (M {sub *}) of the galaxies. Low-mass (log (M {sub *}/M {sub ☉}) < 9.8) galaxies keep an almost constant f {sub clumpy} of ∼60% from z ∼ 3 to z ∼ 0.5. Intermediate-mass and massive galaxies drop their f {sub clumpy} from 55% at z ∼ 3 to 40% and 15%, respectively, at z ∼ 0.5. We find that (1) the trend of disk stabilization predicted by violent disk instability matches the f {sub clumpy} trend of massive galaxies; (2) minor mergers are a viable explanation of the f {sub clumpy} trend of intermediate-mass galaxies at z < 1.5, given a realistic observability timescale; and (3) major mergers are unlikely responsible for the f {sub clumpy} trend in all masses at z < 1.5. The clump contribution to the rest-frame UV light of star-forming galaxies shows a broad peak around galaxies with log (M {sub *}/M {sub

  12. Soft versus hard X-ray emission in active galactic nuclei: partial-covering and warm-plus-cold absorber models

    NASA Astrophysics Data System (ADS)

    Ceballos, M. T.; Barcons, X.

    1996-09-01

    We analyse the ROSAT Position Sensitive Proportional Counter (PSPC) hardness ratio and the 0.5-2-keV to 2-10-keV flux ratio of 65 active galactic nuclei (AGN) for which there are both ROSAT archival observations available and 2-10-keV fluxes, mostly from the HEAO-1 MC-LASS survey. We conclude that the simplest spectral model for the AGN that can accommodate the variety of X-ray colours obtained is a standard power law (with energy spectral index alpha~0.9) plus a ~0.1-keV blackbody, both of which are partially absorbed. In our sample, type 1 AGN require an absorbing column around 10^22 cm^-2 with covering fractions between 20 and 100 per cent, while type 2 AGN display larger columns and ~100 per cent coverage. This simple model also provides a good link between soft and hard AGN X-ray luminosity functions and source counts. We also consider a warm absorber as an alternative model to partial covering and find that the presence of gas in two phases (ionized and neutral) is required.

  13. Formation and evolution of clumpy tidal tails in globular clusters

    NASA Astrophysics Data System (ADS)

    Di Matteo, P.; Miocchi, P.; Capuzzo Dolcetta, R.

    2004-05-01

    Numerical simulations of a globular cluster orbiting in the central region of a triaxial galaxy have been performed, in order to study the formation and subsequent evolution of tidal tails and their main features. Tails begin to form after about a quarter of the cluster orbital period and tend to lie along its orbit, with a leading tail that precedes the cluster and an outer tail that trails behind it. Tails show clumpy substructures; the most prominent ones (for a globular cluster moving on a quasi-circular orbit around the galaxy) are located at a distance from the cluster center between 50 pc and 80 pc and, after 3 orbital periods, contain about 10% of the cluster mass at that epoch. The morphology of tails and clumps will be compared with available observational data, in particular with that concerning Palomar 5, for which evident clumps in the tails have been detected. Kinematical properties of stars in the tails (line-of-sight velocities and velocity dispersion profiles) will be presented and compared to kinematical data of M15 and ω Centauri, two galactic globular clusters for which there is evidence that the velocity dispersion remains constant at large radii. All the simulations have been performed with our own implementation of a tree-code, that uses a multipolar expansion of the potential truncated at the quadrupole moment and that ran on high performance computers employing an original parallelization approach implemented via MPI routines. The time-integration of the `particles' trajectories is performed by a 2nd order leap-frog algorithm, using individual and variable time-steps. Part of this work has been done using the IBM SP4 platform located at CINECA (Bologna, Italy) thanks to the grant inarm007 obtained in the framework of INAF-CINECA agreements.

  14. AGN Survey to characterize the clumpy torus using FORCAST

    NASA Astrophysics Data System (ADS)

    Lopez-Rodriguez, Enrique

    2015-10-01

    A geometrically and optically thick torus of gas and dust obscures the black hole and accretion disk in active galactic nuclei (AGN) in some lines of sight. One of the most important question that still remain uncertain is: How do the properties, such as torus geometry and distribution of clumps, of the torus depend on the AGN luminosity and/or activity class? Infrared (IR) observations are essential to these investigations as the torus intercepts and re-radiates (peaking within 30-40 um) a substantial amount of flux from the central engine. Near-IR (NIR) and mid-IR (MIR) observations from the ground have been key to advance our knowledge in this field. However, the atmosphere is opaque to the 30-40 um range and observations are impossible from ground-based telescopes. FORCAST presents a unique opportunity to explore AGN, providing the best angular resolution observations within the 30-40 um range for the current suite of instruments. From our analysis using Cycle 2 observations, we found that FORCAST provides the largest constraining power of the clumpy torus models in the suggested wavelength range. We therefore request an AGN Survey using FORCAST of snapshot imaging observations of a flux-limited (>500 mJy at 37.1 um) sample of 23 Seyfert galaxies with existing high-angular resolution MIR spectra observed on 8-m class telescopes. Using the FORCAST data requested here in combination with already acquired NIR and MIR data, we will have an unprecedentedly homogeneous AGN sample of IR (1-40 um) SED at the largest spatial-resolution, which yield to a better knowledge of the torus structure in the AGN unified model.

  15. Sound Absorbers

    NASA Astrophysics Data System (ADS)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  16. VizieR Online Data Catalog: NGC2548 clumpy spatial and kinematic structure (Vicente+, 2016)

    NASA Astrophysics Data System (ADS)

    Vicente, B.; Sanchez, N.; Alfaro, E.

    2016-10-01

    We used precise astrometric data from the Carte du Ciel - San Fernando catalogue to study the clumpy structure in NGC 2548. We have completed our spatial and kinematic information with photometric data from the UCAC4 catalogue. With this, we derived positions and proper motions for each of the detected cores in this cluster. This table contains all the astrometric and photometric data for the 1655 stars toward NGC 2548. (1 data file).

  17. An X-ray spectral model for clumpy tori in active galactic nuclei

    SciTech Connect

    Liu, Yuan; Li, Xiaobo E-mail: lixb@ihep.ac.cn

    2014-05-20

    We construct an X-ray spectral model for the clumpy torus in an active galactic nucleus (AGN) using Geant4, which includes the physical processes of the photoelectric effect, Compton scattering, Rayleigh scattering, γ conversion, fluorescence line, and Auger process. Since the electrons in the torus are expected to be bounded instead of free, the deviation of the scattering cross section from the Klein-Nishina cross section has also been included, which changes the X-ray spectra by up to 25% below 10 keV. We have investigated the effect of the clumpiness parameters on the reflection spectra and the strength of the fluorescent line Fe Kα. The volume filling factor of the clouds in the clumpy torus only slightly influences the reflection spectra, however, the total column density and the number of clouds along the line of sight significantly change the shapes and amplitudes of the reflection spectra. The effect of column density is similar to the case of a smooth torus, while a small number of clouds along the line of sight will smooth out the anisotropy of the reflection spectra and the fluorescent line Fe Kα. The smoothing effect is mild in the low column density case (N {sub H} = 10{sup 23} cm{sup –2}), whereas it is much more evident in the high column density case (N {sub H} = 10{sup 25} cm{sup –2}). Our model provides a quantitative tool for the spectral analysis of the clumpy torus. We suggest that the joint fits of the broad band spectral energy distributions of AGNs (from X-ray to infrared) should better constrain the structure of the torus.

  18. A Game of Hide and Seek: Expectations of Clumpy Resources Influence Hiding and Searching Patterns

    PubMed Central

    Wilke, Andreas; Minich, Steven; Panis, Megane; Langen, Tom A.; Skufca, Joseph D.; Todd, Peter M.

    2015-01-01

    Resources are often distributed in clumps or patches in space, unless an agent is trying to protect them from discovery and theft using a dispersed distribution. We uncover human expectations of such spatial resource patterns in collaborative and competitive settings via a sequential multi-person game in which participants hid resources for the next participant to seek. When collaborating, resources were mostly hidden in clumpy distributions, but when competing, resources were hidden in more dispersed (random or hyperdispersed) patterns to increase the searching difficulty for the other player. More dispersed resource distributions came at the cost of higher overall hiding (as well as searching) times, decreased payoffs, and an increased difficulty when the hider had to recall earlier hiding locations at the end of the experiment. Participants’ search strategies were also affected by their underlying expectations, using a win-stay lose-shift strategy appropriate for clumpy resources when searching for collaboratively-hidden items, but moving equally far after finding or not finding an item in competitive settings, as appropriate for dispersed resources. Thus participants showed expectations for clumpy versus dispersed spatial resources that matched the distributions commonly found in collaborative versus competitive foraging settings. PMID:26154661

  19. A Game of Hide and Seek: Expectations of Clumpy Resources Influence Hiding and Searching Patterns.

    PubMed

    Wilke, Andreas; Minich, Steven; Panis, Megane; Langen, Tom A; Skufca, Joseph D; Todd, Peter M

    2015-01-01

    Resources are often distributed in clumps or patches in space, unless an agent is trying to protect them from discovery and theft using a dispersed distribution. We uncover human expectations of such spatial resource patterns in collaborative and competitive settings via a sequential multi-person game in which participants hid resources for the next participant to seek. When collaborating, resources were mostly hidden in clumpy distributions, but when competing, resources were hidden in more dispersed (random or hyperdispersed) patterns to increase the searching difficulty for the other player. More dispersed resource distributions came at the cost of higher overall hiding (as well as searching) times, decreased payoffs, and an increased difficulty when the hider had to recall earlier hiding locations at the end of the experiment. Participants' search strategies were also affected by their underlying expectations, using a win-stay lose-shift strategy appropriate for clumpy resources when searching for collaboratively-hidden items, but moving equally far after finding or not finding an item in competitive settings, as appropriate for dispersed resources. Thus participants showed expectations for clumpy versus dispersed spatial resources that matched the distributions commonly found in collaborative versus competitive foraging settings.

  20. Supermassive black hole pairs in clumpy galaxies at high redshift: delayed binary formation and concurrent mass growth

    NASA Astrophysics Data System (ADS)

    Tamburello, Valentina; Capelo, Pedro R.; Mayer, Lucio; Bellovary, Jillian M.; Wadsley, James W.

    2017-01-01

    Massive gas-rich galaxy discs at z ˜ 1-3 host massive star-forming clumps with typical baryonic masses in the range 107-108 M⊙ which can affect the orbital decay and concurrent growth of supermassive black hole (BH) pairs. Using a set of high-resolution simulations of isolated clumpy galaxies hosting a pair of unequal-mass BHs, we study the interaction between massive clumps and a BH pair at kiloparsec scales, during the early phase of the orbital decay. We find that both the interaction with massive clumps and the heating of the cold gas layer of the disc by BH feedback tend to delay significantly the orbital decay of the secondary, which in many cases is ejected and then hovers for a whole gigayear around a separation of 1-2 kpc. In the envelope, dynamical friction is weak and there is no contribution of disc torques: these lead to the fastest decay once the orbit of the secondary BH has circularized in the disc mid-plane. In runs with larger eccentricities the delay is stronger, although there are some exceptions. We also show that, even in discs with very sporadic transient clump formation, a strong spiral pattern affects the decay time-scale for BHs on eccentric orbits. We conclude that, contrary to previous belief, a gas-rich background is not necessarily conducive to a fast BH decay and binary formation, which prompts more extensive investigations aimed at calibrating event-rate forecasts for ongoing and future gravitational-wave searches, such as with Pulsar Timing Arrays and the future evolved Laser Interferometer Space Antenna.

  1. Three-dimensional Non-LTE Radiative Transfer of CS in Clumpy Dense Cores

    NASA Astrophysics Data System (ADS)

    Park, Y.-S.; Hong, S. S.

    1998-02-01

    With a Monte Carlo radiative transfer code we have investigated excitation conditions of the CS molecule in dense cores and synthesized line profiles for several transitions of both CS and C34S. We took two kinds of models of the dense core: a clumpy and a smooth model. In the clumpy model, the core is composed of many small clumps, whose volume filling factor f is unity in the central region of r <= 0.2R and then declines as f ~ r-1.5. However, H2 number density in the clump is kept constant and also independent of the clump position. The mean number density, nH2(r), is thus constant in the central part and then decreases as the same power law. In the smooth model, the gas fills the core completely, and its local density exactly follows the mean density of the clumpy model. For both models, each clump has thermal as well as bulk motions, velocity dispersion of the latter being proportional to r0.5. In the clumpy structured core, the excitation temperature of the CS transitions is found to be generally constant over an entire region. As a consequence, the synthesized profile is of a Gaussian shape superposed with some wiggles, which reflects the existence of clumps under the bulk motion. The trend of flat distribution of excitation temperature becomes more prominent for optically thin transitions of the rarer species C34S. The profiles develop flat-top features with minor wiggles only when the core becomes extremely thick in the optical sense. On the other hand, wider profiles that have self-absorption are synthesized in the smooth core. The self-absorption is formed by a steep gradient in the radial distribution of the excitation temperature. For optically thin C34S transitions, both the clumpy and the smooth cores exhibit profiles close to a Gaussian shape. Comparing line parameters derived in the Monte Carlo code and those by the large-scale velocity gradient calculations, we found that only the clumpy models can give correct estimations of the density and

  2. Cold Stress

    MedlinePlus

    ... Publications and Products Programs Contact NIOSH NIOSH COLD STRESS Recommend on Facebook Tweet Share Compartir Workers who ... cold environments may be at risk of cold stress. Extreme cold weather is a dangerous situation that ...

  3. Interaction of clumpy dark matter with interstellar medium in astrophysical systems

    NASA Astrophysics Data System (ADS)

    Baushev, A. N.

    2012-02-01

    Contemporary cosmological conceptions suggest that the dark matter in haloes of galaxies and galaxy clusters has most likely a clumpy structure. If a stream of gas penetrates through it, a small-scale gravitational field created by the clumps disturbs the flow resulting in momentum exchange between the stream and the dark matter. In this article, we perform an analysis of this effect, based on the hierarchical halo model of the dark matter structure and Navarro-Frenk-White density profiles. We consider the clumps of various masses, from the smallest up to the highest ones M≥ 109 M⊙. It has been found that in any event the effect grows with the mass of the clump: not only the drag force ? acting on the clump but also its acceleration ? increases. We discuss various astrophysical systems. The mechanism proved to be ineffective in the case of galaxy or galaxy cluster collisions. On the other hand, it played an important role during the process of galaxy formation. As a result, the dark matter should have formed a more compact, oblate and faster rotating substructure in the halo of our Galaxy. We have shown that this thick disc should be more clumpy than the halo. This fact is very important for the indirect detection experiments since it is the clumps that give the main contribution to the annihilation signal. Our calculations show that the mechanism of momentum exchange between the dark and baryon matter is ineffective on the outskirts of the galactic halo. It means that the clumps from there were not transported to the thick disc, and this region should be more clumpy than the halo on the average.

  4. Modeling optical and UV polarization of AGNs. III. From uniform-density to clumpy regions

    NASA Astrophysics Data System (ADS)

    Marin, F.; Goosmann, R. W.; Gaskell, C. M.

    2015-05-01

    Context. A growing body of evidence suggests that some, if not all, scattering regions of active galactic nuclei (AGNs) are clumpy. The inner AGN components cannot be spatially resolved with current instruments and must be studied by numerical simulations of observed spectroscopy and polarization data. Aims: We run radiative transfer models in the optical/UV for a variety of AGN reprocessing regions with different distributions of clumpy scattering media. We obtain geometry-sensitive polarization spectra and images to improve our previous AGN models and their comparison with the observations. Methods: We use the latest public version 1.2 of the Monte Carlo code stokes presented in the first two papers of this series to model AGN reprocessing regions of increasing morphological complexity. We replace previously uniform-density media with up to thousands of constant-density clumps. We couple a continuum source to fragmented equatorial scattering regions, polar outflows, and toroidal obscuring dust regions and investigate a wide range of geometries. We also consider different levels of fragmentation in each scattering region to evaluate the importance of fragmentation for the net polarization of the AGN. Results: In comparison with uniform-density models, equatorial distributions of gas and dust clouds result in grayer spectra and show a decrease in the net polarization percentage at all lines of sight. The resulting polarization position angle depends on the morphology of the clumpy structure, with extended tori favoring parallel polarization while compact tori produce orthogonal polarization position angles. In the case of polar scattering regions, fragmentation increases the net polarization unless the cloud filling factor is small. A complete AGN model constructed from the individual, fragmented regions can produce low polarization percentages (<2%), with a parallel polarization angle for observer inclinations up to 70° for a torus half opening angle of 60°. For

  5. Characterizing Clumpy Structure of z 2 Galaxies in HST Observations from CANDELS and Hydrodynamical Simulations

    NASA Astrophysics Data System (ADS)

    Mozena, Mark; Faber, S. M.; Primack, J. R.; Dekel, A.; Ceverino, D.; Koo, D. C.; Fumagalli, M.; Wuyts, S.; Rosario, D. J.; Lai, K.; Kocevski, D. D.; McGrath, E. J.; Trump, J. R.; CANDELS

    2011-01-01

    The first data from the HST Multi-Cycle Treasury CANDELS (Cosmic Assembly Near Infra-red Deep Extragalactic Legacy Survey - candels.ucolick.org) are producing images of thousands of z 2 galaxies in observed optical (ACS) and NIR (WFC3) bands. We have developed a new visual classification scheme for z 2 galaxies which is motivated by the significant population of galaxies that are dominated by giant clumps in the HST images, and by the theoretical predictions for clumpy galaxies based on analytic studies and zoom-in hydrodynamical cosmological simulations. This classification method was developed using about a thousand z 2 galaxies in the GOODS-S Early Release Survey (ERS) region imaged with ACS and WFC3. The ERS data have been observed in a way similar to the CANDELS observations. I will also discuss the latest cosmologically motivated ART hydrodynamical simulations by Ceverino, Dekel, and Primack. We render these simulated z 2 galaxies to mimic our HST ACS and WFC3 images and visually classify their stellar structure to compare them with the galaxies observed in ERS. We have compared the effects of dust extinction due to the complex clumpy distribution of gas within these simulations. Comparing the visual classification of the HST observations with the simulations provides new clues to galaxy assembly.

  6. Common Cold

    MedlinePlus

    ... nose, coughing - everyone knows the symptoms of the common cold. It is probably the most common illness. In ... avoid colds. There is no cure for the common cold. For relief, try Getting plenty of rest Drinking ...

  7. NGC 2548: clumpy spatial and kinematic structure in an intermediate-age Galactic cluster

    NASA Astrophysics Data System (ADS)

    Vicente, Belén; Sánchez, Néstor; Alfaro, Emilio J.

    2016-09-01

    NGC 2548 is a ˜400-500 Myr old open cluster with evidence of spatial substructures likely caused by its interaction with the Galactic disc. In this work we use precise astrometric data from the Carte du Ciel - San Fernando (CdC-SF) catalogue to study the clumpy structure in this cluster. We confirm the fragmented structure of NGC 2548 but, additionally, the relatively high precision of our kinematic data lead us to the first detection of substructures in the proper motion space of a stellar cluster. There are three spatially separated cores each of which has its own counterpart in the proper motion distribution. The two main cores lie nearly parallel to the Galactic plane whereas the third one is significantly fainter than the others and it moves towards the Galactic plane separating from the rest of the cluster. We derive core positions and proper motions, as well as the stars belonging to each core.

  8. Sub-millimeter Galaxies: Dusty, Clumpy and Messy Starbursts in the Distant Universe

    NASA Astrophysics Data System (ADS)

    Menéndez-Delmestre, K.; Blain, A. W.; Swinbank, M.; Smail, I.; Ivison, R.; Chapman, S. C.; Gonçalves, T. S.

    2014-10-01

    We present the first spatially-resolved observations of the Hα emission in three z˜2 sub-millimeter selected galaxies (SMGs) using the Keck OH-Suppressing Infrared Imaging Spectrograph (OSIRIS) with Laser Guide Star Adaptive Optics (LGS-AO). With the unprecedent kpc-scale resolution - up to ten times that achieved with previous seeing-limited studies - and the kinematic insight that these observations provide, we unveil a clumpy Hα structure and reveal velocity offsets that suggest these systems are in an advanced merging phase. The spatially-resolved spectral information also allows us to disentangle the Hα emission arising from an active galactic nucleus (AGN) from that associated with star formation.

  9. Radiative Transfer Model of Dust Attenuation Curves in Clumpy, Galactic Environments

    NASA Astrophysics Data System (ADS)

    Seon, Kwang-Il; Draine, Bruce T.

    2016-12-01

    The attenuation of starlight by dust in galactic environments is investigated through models of radiative transfer in a spherical, clumpy interstellar medium (ISM). We show that the attenuation curves are primarily determined by the wavelength dependence of absorption rather than by the underlying extinction (absorption+scattering) curve; the observationally derived attenuation curves cannot constrain a unique extinction curve unless the absorption or scattering efficiency is specified. Attenuation curves consistent with the “Calzetti curve” are found by assuming the silicate-carbonaceous dust model for the Milky Way (MW), but with the 2175 Å bump suppressed or absent. The discrepancy between our results and previous work that claimed the Small Magellanic Cloud dust to be the origin of the Calzetti curve is ascribed to the difference in adopted albedos; we use the theoretically calculated albedos, whereas the previous works adopted albedos derived empirically from observations of reflection nebulae. It is found that the attenuation curves calculated with the MW dust model are well represented by a modified Calzetti curve with a varying slope and UV bump strength. The strong correlation between the slope and UV bump strength, as found in star-forming galaxies at 0.5\\lt z\\lt 2.0, is well reproduced when the abundance of the UV bump carriers is assumed to be 30%-40% of that of the MW dust; radiative transfer effects lead to shallower attenuation curves with weaker UV bumps as the ISM is more clumpy and dustier. We also argue that some local starburst galaxies have a UV bump in their attenuation curves, albeit very weak.

  10. Searching for AGN Signatures in HST WFC3/IR Grism Spectra of Clumpy Galaxies at 0.5 < z < 2

    NASA Astrophysics Data System (ADS)

    Han, Anna; Schawinski, K.; Simmons, B. D.; Urry, C. M.; Glikman, E.; Bamford, S.; Lintott, C.

    2012-01-01

    The recent discovery of a "clumpy” galaxy with three actively growing black holes in separate clumps at z = 1.35 raises the possibility of supermassive black holes (SMBHs) forming in situ within gas clouds at later epochs than previously expected. We carry out a systematic search for 0.5 < z < 2 galaxies containing multiple active galactic nuclei (AGN) by examining clumpy galaxies with Hubble Space Telescope WFC3/IR grism survey data. We select our sample of clumpy galaxies using SExtractor and galaxy classifications from the Hubble Zoo citizen science project. We then analyze the grism data of individual clumps within each galaxy to characterize the probability of SMBHs forming and growing in the clumps of forming disk galaxies at 0.5 < z < 2.

  11. No more active galactic nuclei in clumpy disks than in smooth galaxies at z ∼ 2 in CANDELS/3D-HST

    SciTech Connect

    Trump, Jonathan R.; Luo, Bin; Brandt, W. N.; Barro, Guillermo; Guo, Yicheng; Koo, David C.; Faber, S. M.; Brammer, Gabriel B.; Ferguson, Henry C.; Grogin, Norman A.; Kartaltepe, Jeyhan; Koekemoer, Anton M.; Bell, Eric F.; Dekel, Avishai; Hopkins, Philip F.; Kocevski, Dale D.; McIntosh, Daniel H.; Momcheva, Ivelina; and others

    2014-10-01

    We use CANDELS imaging, 3D-HST spectroscopy, and Chandra X-ray data to investigate if active galactic nuclei (AGNs) are preferentially fueled by violent disk instabilities funneling gas into galaxy centers at 1.3 < z < 2.4. We select galaxies undergoing gravitational instabilities using the number of clumps and degree of patchiness as proxies. The CANDELS visual classification system is used to identify 44 clumpy disk galaxies, along with mass-matched comparison samples of smooth and intermediate morphology galaxies. We note that despite being mass-matched and having similar star formation rates, the smoother galaxies tend to be smaller disks with more prominent bulges compared to the clumpy galaxies. The lack of smooth extended disks is probably a general feature of the z ∼ 2 galaxy population, and means we cannot directly compare with the clumpy and smooth extended disks observed at lower redshift. We find that z ∼ 2 clumpy galaxies have slightly enhanced AGN fractions selected by integrated line ratios (in the mass-excitation method), but the spatially resolved line ratios indicate this is likely due to extended phenomena rather than nuclear AGNs. Meanwhile, the X-ray data show that clumpy, smooth, and intermediate galaxies have nearly indistinguishable AGN fractions derived from both individual detections and stacked non-detections. The data demonstrate that AGN fueling modes at z ∼ 1.85—whether violent disk instabilities or secular processes—are as efficient in smooth galaxies as they are in clumpy galaxies.

  12. Modelling clumpy photon-dominated regions in 3D. Understanding the Orion Bar stratification

    NASA Astrophysics Data System (ADS)

    Andree-Labsch, S.; Ossenkopf-Okada, V.; Röllig, M.

    2017-01-01

    Context. Models of photon-dominated regions (PDRs) still fail to fully reproduce some of the observed properties. In particular they do not reproduce the combination of the intensities of different PDR cooling lines together with the chemical stratification, as observed for example for the Orion Bar PDR. Aims: We aim to construct a numerical PDR model, KOSMA-τ 3D, to simulate full spectral cubes of line emission from arbitrary PDRs in three dimensions (3D). The model will reproduce the intensity of the main cooling lines from the Orion Bar PDR and the observed layered structure of the different transitions. Methods: We built up a 3D compound, made of voxels (3D pixels) that contain a discrete mass distribution of spherical "clumpy" structures, approximating the fractal ISM. To analyse each individual clump the new code was combined with the KOSMA-τ PDR model. Probabilistic algorithms were used to calculate the local FUV flux for each voxel as well as the voxel-averaged line emissivities and optical depths, based on the properties of the individual clumps. Finally, the computation of the radiative transfer through the compound provided full spectral cubes. To test the new model we tried to simulate the structure of the Orion Bar PDR and compared the results to observations from HIFI/Herschel and from the Caltech Submillimetre Observatory (CSO). In this context new Herschel data from the HEXOS guaranteed-time key program is presented. Results: Our model is able to reproduce the line-integrated intensities within a factor of 2.5 and the observed stratification pattern within 0.016 pc for the [Cii] 158 μm and different 12/13CO and HCO+ transitions, based on the representation of the Orion Bar PDR by a clumpy edge-on cavity wall. In the cavity wall, a large fraction of the total mass needs to be contained in clumps. The mass of the interclump medium is constrained by the FUV penetration. Furthermore, the stratification profile cannot be reproduced by a model that has

  13. Astrochemical Properties of Planck Cold Clumps

    NASA Astrophysics Data System (ADS)

    Tatematsu, Ken’ichi; Liu, Tie; Ohashi, Satoshi; Sanhueza, Patricio; Nguyễn Lu’o’ng, Quang; Hirota, Tomoya; Liu, Sheng-Yuan; Hirano, Naomi; Choi, Minho; Kang, Miju; Thompson, Mark A.; Fuller, Gary; Wu, Yuefang; Li, Di; Di Francesco, James; Kim, Kee-Tae; Wang, Ke; Ristorcelli, Isabelle; Juvela, Mika; Shinnaga, Hiroko; Cunningham, Maria; Saito, Masao; Lee, Jeong-Eun; Tóth, L. Viktor; He, Jinhua; Sakai, Takeshi; Kim, Jungha; JCMT Large Program “SCOPE” collaboration; TRAO Key Science Program “TOP” collaboration

    2017-02-01

    We observed 13 Planck cold clumps with the James Clerk Maxwell Telescope/SCUBA-2 and with the Nobeyama 45 m radio telescope. The N2H+ distribution obtained with the Nobeyama telescope is quite similar to SCUBA-2 dust distribution. The 82 GHz HC3N, 82 GHz CCS, and 94 GHz CCS emission are often distributed differently with respect to the N2H+ emission. The CCS emission, which is known to be abundant in starless molecular cloud cores, is often very clumpy in the observed targets. We made deep single-pointing observations in DNC, HN13C, N2D+, and cyclic-C3H2 toward nine clumps. The detection rate of N2D+ is 50%. Furthermore, we observed the NH3 emission toward 15 Planck cold clumps to estimate the kinetic temperature, and confirmed that most targets are cold (≲20 K). In two of the starless clumps we observed, the CCS emission is distributed as it surrounds the N2H+ core (chemically evolved gas), which resembles the case of L1544, a prestellar core showing collapse. In addition, we detected both DNC and N2D+. These two clumps are most likely on the verge of star formation. We introduce the chemical evolution factor (CEF) for starless cores to describe the chemical evolutionary stage, and analyze the observed Planck cold clumps.

  14. Common cold

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000678.htm Common cold To use the sharing features on this page, please enable JavaScript. The common cold most often causes a runny nose, nasal congestion, ...

  15. Nature of the warm absorber outflow in NGC 4051

    NASA Astrophysics Data System (ADS)

    Mizumoto, Misaki; Ebisawa, Ken

    2017-04-01

    The narrow-line Seyfert 1 galaxy NGC 4051 is known to exhibit significant X-ray spectral/flux variations and have a number of emission/absorption features. X-ray observations have revealed that these absorption features are blueshifted, which indicates that NGC 4051 has warm absorber outflow. In order to constrain physical parameters of the warm absorber outflow, we analyse the archival data with the longest exposure taken by XMM-Newton in 2009. We calculate the root-mean-square (rms) spectra with the grating spectral resolution for the first time. The rms spectra have a sharp peak and several dips, which can be explained by variable absorption features and non-variable emission lines; a lower ionized warm absorber (WA1: log ξ = 1.5, v = -650 km s-1) shows large variability, whereas higher ionized warm absorbers (WA2: log ξ = 2.5, v = -4100 km s-1, WA3: log ξ = 3.4, v = -6100 km s-1) show little variability. WA1 shows the maximum variability at a time-scale of ∼104 s, suggesting that the absorber locates at ∼103 times of the Schwarzschild radius. The depth of the absorption features due to WA1 and the observed soft X-ray flux are anticorrelated in several observational sequences, which can be explained by variation of partial covering fraction of the double-layer blobs that are composed of the Compton-thick core and the ionized layer (=WA1). WA2 and WA3 show little variability and presumably extend uniformly in the line of sight. The present result shows that NGC 4051 has two types of the warm absorber outflows; the static, high-ionized and extended line-driven disc winds and the variable, low-ionized and clumpy double-layer blobs.

  16. Resonance Absorption of Laser Light by Warm and Cold Plasmas.

    DTIC Science & Technology

    1981-03-01

    34 Ponderomotive Force................38 Hot Electron Energy ................40 Validity bf Assumptions..............41 V. Conclusions...Indicated by Arrows) for the Warm and Cold Plasma Models ..... ................ 31 7 Cold Plasma: Fraction of Laser Energy Resonantly Absorbed as a...Function of Incident Angle .. ............ 35 8 Warm Plasma: Fraction of Laser Energy Resonantly Absorbed as a Function of Incident Angle (T = 637 ev and

  17. Extreme Gas Fractions in Clumpy, Turbulent Disk Galaxies at z ~ 0.1

    NASA Astrophysics Data System (ADS)

    Fisher, David B.; Glazebrook, Karl; Bolatto, Alberto; Obreschkow, Danail; Mentuch Cooper, Erin; Wisnioski, Emily; Bassett, Robert; Abraham, Roberto G.; Damjanov, Ivana; Green, Andy; McGregor, Peter

    2014-08-01

    In this Letter, we report the discovery of CO fluxes, suggesting very high gas fractions in three disk galaxies seen in the nearby universe (z ~ 0.1). These galaxies were investigated as part of the DYnamics of Newly Assembled Massive Objects (DYNAMO) survey. High-resolution Hubble Space Telescope imaging of these objects reveals the presence of large star forming clumps in the bodies of the galaxies, while spatially resolved spectroscopy of redshifted Hα reveals the presence of high dispersion rotating disks. The internal dynamical state of these galaxies resembles that of disk systems seen at much higher redshifts (1 < z < 3). Using CO(1-0) observations made with the Plateau de Bure Interferometer, we find gas fractions of 20%-30% and depletion times of t dep ~ 0.5 Gyr (assuming a Milky-Way-like αCO). These properties are unlike those expected for low-redshift galaxies of comparable specific star formation rate, but they are normal for their high-z counterparts. DYNAMO galaxies break the degeneracy between gas fraction and redshift, and we show that the depletion time per specific star formation rate for galaxies is closely tied to gas fraction, independent of redshift. We also show that the gas dynamics of two of our local targets corresponds to those expected from unstable disks, again resembling the dynamics of high-z disks. These results provide evidence that DYNAMO galaxies are local analogs to the clumpy, turbulent disks, which are often found at high redshift.

  18. From Mirrors to Windows: Lyman-alpha Radiative Transfer in a Very Clumpy Medium

    NASA Astrophysics Data System (ADS)

    Gronke, Max; Dijkstra, Mark; McCourt, Michael; Oh, S. Peng

    2016-12-01

    Lyman-alpha (Lyα) is the strongest emission line in the universe and is frequently used to detect and study the most distant galaxies. Because Lyα is a resonant line, photons typically scatter prior to escaping; this scattering process complicates the interpretation of Lyα spectra, but also encodes a wealth of information about the structure and kinematics of neutral gas in the Galaxy. Modeling the Lyα line therefore allows us to study tiny-scale features of the gas. Curiously, observed Lyα spectra can be modeled successfully with very simple, homogeneous geometries (such as an expanding, spherical shell), whereas more realistic, multiphase geometries often fail to reproduce the observed spectra. This seems paradoxical since the gas in galaxies is known to be multiphase. In this Letter, we show that spectra emerging from clumpy geometries with a large number (≳ 10 for a clump column density of {N}{{H}{{I}},{cl}}∼ {10}17 {{cm}}-2) of clouds along the line of sight converge to the predictions from simplified, homogeneous models. We suggest that this resolves the apparent discrepancy and may provide a way to study the gas structure in galaxies on scales far smaller than can be probed in either cosmological simulations or direct (i.e., spatially resolved) observations.

  19. Energy-Absorbing, Lightweight Wheels

    NASA Technical Reports Server (NTRS)

    Waydo, Peter

    2003-01-01

    Improved energy-absorbing wheels are under development for use on special-purpose vehicles that must traverse rough terrain under conditions (e.g., extreme cold) in which rubber pneumatic tires would fail. The designs of these wheels differ from those of prior non-pneumatic energy-absorbing wheels in ways that result in lighter weights and more effective reduction of stresses generated by ground/wheel contact forces. These wheels could be made of metals and/or composite materials to withstand the expected extreme operating conditions. As shown in the figure, a wheel according to this concept would include an isogrid tire connected to a hub via spring rods. The isogrid tire would be a stiff, lightweight structure typically made of aluminum. The isogrid aspect of the structure would both impart stiffness and act as a traction surface. The hub would be a thin-walled body of revolution having a simple or compound conical or other shape chosen for structural efficiency. The spring rods would absorb energy and partially isolate the hub and the supported vehicle from impact loads. The general spring-rod configuration shown in the figure was chosen because it would distribute contact and impact loads nearly evenly around the periphery of the hub, thereby helping to protect the hub against damage that would otherwise be caused by large loads concentrated onto small portions of the hub.

  20. Composition for absorbing hydrogen

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Enz, Glenn L.

    1995-01-01

    A hydrogen absorbing composition. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  1. Composition for absorbing hydrogen

    DOEpatents

    Heung, L.K.; Wicks, G.G.; Enz, G.L.

    1995-05-02

    A hydrogen absorbing composition is described. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  2. Wing galaxies: A formation mechanism of the clumpy irregular galaxy Markarian 297

    NASA Technical Reports Server (NTRS)

    Taniguchi, Yoshiaki; Noguchi, Masafumi

    1990-01-01

    In order to contribute to an understanding of collision-induced starburst activities, the authors present a detailed case study on the starburst galaxy Markarian 297 (= NGC 6052 = Arp 209; hereafter Mrk 297). This galaxy is classified as a clumpy irregular galaxy (CIG) according to its morphological properties (cf. Heidmann, 1987). Two major clumps and many small clumps are observed in the entire region of Mrk 297 (Hecquet, Coupinot, and Maucherat 1987). The overall morphology of Mrk 297 is highly chaotic and thus it seems difficult to determine possible orbits of galaxy-galaxy collision. However, the authors have serendipitously found a possible orbit during a course of numerical simulations for a radial-penetration collision between galaxies. The radial-penetration collision means that an intruder penetrates a target galaxy radially passing by its nucleus. This kind of collision is known to explain a formation mechanism of ripples around disk galaxies (Wallin and Struck-Marcell 1988). Here, the authors show that the radial-penetration collision between galaxies successfully explains both overall morphological and kinematical properties of Mrk 297. The authors made two kinds of numerical simulations for Mrk 297. One is N-body (1x10(exp 4) particles) simulations in which effects of self gravity of the stellar disk are taken into account. These simulations are used to study detailed morphological feature of Mrk 297. The response of gas clouds are also investigated in order to estimate star formation rates in such collisions. The other is test-particle simulations, which are utilized to obtain a rough picture of Mrk 297 and to analyze the velocity field of Mrk 297. The techniques of the numerical simulations are the same as those in Noguchi (1988) and Noguchi and Ishibashi (1986). In the present model, an intruding galaxy with the same mass of a target galaxy moves on a rectilinear orbit which passes the center of the target.

  3. EXTREME GAS FRACTIONS IN CLUMPY, TURBULENT DISK GALAXIES AT z ∼ 0.1

    SciTech Connect

    Fisher, David B.; Glazebrook, Karl; Bassett, Robert; Bolatto, Alberto; Obreschkow, Danail; Cooper, Erin Mentuch; Wisnioski, Emily; Abraham, Roberto G.; Damjanov, Ivana; Green, Andy; McGregor, Peter

    2014-08-01

    In this Letter, we report the discovery of CO fluxes, suggesting very high gas fractions in three disk galaxies seen in the nearby universe (z ∼ 0.1). These galaxies were investigated as part of the DYnamics of Newly Assembled Massive Objects (DYNAMO) survey. High-resolution Hubble Space Telescope imaging of these objects reveals the presence of large star forming clumps in the bodies of the galaxies, while spatially resolved spectroscopy of redshifted Hα reveals the presence of high dispersion rotating disks. The internal dynamical state of these galaxies resembles that of disk systems seen at much higher redshifts (1 < z < 3). Using CO(1-0) observations made with the Plateau de Bure Interferometer, we find gas fractions of 20%-30% and depletion times of t {sub dep} ∼ 0.5 Gyr (assuming a Milky-Way-like α{sub CO}). These properties are unlike those expected for low-redshift galaxies of comparable specific star formation rate, but they are normal for their high-z counterparts. DYNAMO galaxies break the degeneracy between gas fraction and redshift, and we show that the depletion time per specific star formation rate for galaxies is closely tied to gas fraction, independent of redshift. We also show that the gas dynamics of two of our local targets corresponds to those expected from unstable disks, again resembling the dynamics of high-z disks. These results provide evidence that DYNAMO galaxies are local analogs to the clumpy, turbulent disks, which are often found at high redshift.

  4. NEAR-INFRARED REVERBERATION BY DUSTY CLUMPY TORI IN ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Kawaguchi, Toshihiro; Mori, Masao

    2011-08-20

    According to recent models, the accretion disk and black hole in active galactic nuclei (AGNs) are surrounded by a clumpy torus. We investigate the NIR flux variation of the torus in response to a UV flash for various geometries. Anisotropic illumination by the disk and the torus self-occultation contrast our study with earlier works. Both the waning effect of each clump and the torus self-occultation selectively reduce the emission from the region with a short delay. Therefore, the NIR delay depends on the viewing angle (where a more inclined angle leads to a longer delay), and the time response shows an asymmetric profile with negative skewness, opposing the results for optically thin tori. The range of the computed delay coincides with the observed one, suggesting that the viewing angle is primarily responsible for the scatter of the observed delay. We also propose that the red NIR-to-optical color of type 1.8/1.9 objects is caused not only by the dust extinction but also the intrinsically red color. Compared with the modest torus thickness, both a thick and a thin tori display weaker NIR emission. A selection bias is thus expected such that NIR-selected AGNs tend to possess moderately thick tori. A thicker torus shows a narrower and more heavily skewed time profile, while a thin torus produces a rapid response. A super-Eddington accretion rate leads to much weaker NIR emission due to the disk self-occultation and the disk truncation by self-gravity. A long delay is expected from an optically thin and/or a largely misaligned torus. Very weak NIR emission, such as in hot-dust-poor active nuclei, can arise from a geometrically thin torus, a super-Eddington accretion rate, or a slightly misaligned torus.

  5. EVIDENCE FOR A CLUMPY, ROTATING GAS DISK IN A SUBMILLIMETER GALAXY AT z = 4

    SciTech Connect

    Hodge, J. A.; Walter, F.; Carilli, C. L.; De Blok, W. J. G.; Riechers, D.; Daddi, E.

    2012-11-20

    We present Karl G. Jansky Very Large Array observations of the CO(2-1) emission in the z = 4.05 submillimeter galaxy (SMG) GN20. These high-resolution data allow us to image the molecular gas at 1.3 kpc resolution just 1.6 Gyr after the big bang. The data reveal a clumpy, extended gas reservoir, 14 {+-} 4 kpc in diameter, in unprecedented detail. A dynamical analysis shows that the data are consistent with a rotating disk of total dynamical mass 5.4 {+-} 2.4 Multiplication-Sign 10{sup 11} M {sub Sun }. We use this dynamical mass estimate to constrain the CO-to-H{sub 2} mass conversion factor ({alpha}{sub CO}), finding {alpha}{sub CO} = 1.1 {+-} 0.6 M {sub Sun }(K km s{sup -1} pc{sup 2}){sup -1}. We identify five distinct molecular gas clumps in the disk of GN20 with masses a few percent of the total gas mass, brightness temperatures of 16-31K, and surface densities of >3200-4500 Multiplication-Sign ({alpha}{sub CO}/0.8) M {sub Sun} pc{sup -2}. Virial mass estimates indicate they could be self-gravitating, and we constrain their CO-to-H{sub 2} mass conversion factor to be <0.2-0.7 M {sub Sun }(K km s{sup -1} pc{sup 2}){sup -1}. A multiwavelength comparison demonstrates that the molecular gas is concentrated in a region of the galaxy that is heavily obscured in the rest-frame UV/optical. We investigate the spatially resolved gas excitation and find that the CO(6-5)/CO(2-1) ratio is constant with radius, consistent with star formation occurring over a large portion of the disk. We discuss the implications of our results in the context of different fueling scenarios for SMGs.

  6. Radiative transfer in a clumpy universe: The colors of high-redshift galaxies

    NASA Technical Reports Server (NTRS)

    Madau, Piero

    1995-01-01

    We assess the effects of the stochastic attenuation produced by intervening QSO absorption systems on the broadband colors of galaxies at cosmological distances. We compute the H I opacity of a clumpy universe as a function of redshift, including scattering in resonant lines, such as Lyman alpha, Lyman beta, Lyman gamma, and higher order members, and Lyman-continuum absorption. Both the numerous, optically thin Lyman-alpha forest clouds and the rarer, optically thick Lyman limit systems are found to contribute to the obscuration of background sources. We study the mean properties of primeval galaxies at high redshift in four broad optical passbands, U(sub n), B, G, and R. Even if young galaxies radiated a significant amount of ionizing photons, the attenuation due to the accumulated photoelectric opacity along the path is so severe that sources beyond z approximately 3 will drop out of the U(sub n) image together. We also show that the observed B-R color of distant galaxies can be much redder than expected from a stellar population. At z approximately 3.5, the blanketing by discrete absorption lines in the Lyman series is so effective that background galaxies appear, on average, 1 mag fainter in B. By z approximately 4, the observed B magnitude increment due to intergalactic absorption exceeds 2 mag. By modeling the intrinsic UV spectral energy distribution of star-forming galaxies with a stellar population synthesis code, we show that the (B-R)(sub AB) approximately 0 criterion for identifying 'flat-spectrum,' metal-producing galaxies is biased against objects at z greater than 3. The continuum blanketing from the Lyman series produces a characteristic staircase profile in the transmitted power. We suggest that this cosmic Lyman decrement might be used as a tool to identify high-z galaxies.

  7. MAPPING THE CLUMPY STRUCTURES WITHIN SUBMILLIMETER GALAXIES USING LASER-GUIDE STAR ADAPTIVE OPTICS SPECTROSCOPY

    SciTech Connect

    Menendez-Delmestre, Karin; Goncalves, Thiago S.; Blain, Andrew W.; Swinbank, Mark; Smail, Ian; Ivison, Rob J.; Chapman, Scott C.

    2013-04-20

    We present the first integral-field spectroscopic observations of high-redshift submillimeter-selected galaxies (SMGs) using Laser-Guide Star Adaptive Optics. We target H{alpha} emission of three SMGs at redshifts z {approx} 1.4-2.4 with the OH-Suppressing Infrared Imaging Spectrograph on Keck. The spatially resolved spectroscopy of these galaxies reveals unresolved broad-H{alpha} line regions (FWHM >1000 km s{sup -1}) likely associated with an active galactic nucleus (AGN) and regions of diffuse star formation traced by narrow-line H{alpha} emission (FWHM {approx}< 500 km s{sup -1}) dominated by multiple H{alpha}-bright stellar clumps, each contributing 1%-30% of the total clump-integrated H{alpha} emission. We find that these SMGs host high star formation rate surface densities, similar to local extreme sources, such as circumnuclear starbursts and luminous infrared galaxies. However, in contrast to these local environments, SMGs appear to be undergoing such intense activity on significantly larger spatial scales as revealed by extended H{alpha} emission over 4-16 kpc. H{alpha} kinematics show no evidence of ordered global motion as would be found in a disk, but rather large velocity offsets ({approx}few Multiplication-Sign 100 km s{sup -1}) between the distinct stellar clumps. Together with the asymmetric distribution of the stellar clumps around the AGN in these objects, it is unlikely that we are unveiling a clumpy disk structure as has been suggested in other high-redshift populations of star-forming galaxies. The SMG clumps in this sample may correspond to remnants of originally independent gas-rich systems that are in the process of merging, hence triggering the ultraluminous SMG phase.

  8. Externally tuned vibration absorber

    DOEpatents

    Vincent, Ronald J.

    1987-09-22

    A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

  9. Shock absorber control system

    SciTech Connect

    Nakano, Y.; Ohira, M.; Ushida, M.; Miyagawa, T.; Shimodaira, T.

    1987-01-13

    A shock absorber control system is described for controlling a dampening force of a shock absorber of a vehicle comprising: setting means for setting a desired dampening force changeable within a predetermined range; drive means for driving the shock absorber to change the dampening force of the shock absorber linearly; control means for controlling the drive means in accordance with the desired dampening force when the setting of the desired dampening force has been changed; detecting means for detecting an actual dampening force of the shock absorber; and correcting means for correcting the dampening force of the shock absorber by controlling the drive means in accordance with a difference between the desired dampening force and the detected actual dampening force.

  10. CPCs with segmented absorbers

    SciTech Connect

    Keita, M.; Robertson, H.S. )

    1991-01-01

    One of the most promising means of improving the performance of solar thermal collectors is to reduce the energy lost by the hot absorber. One way to do this, not currently part of the technology, is to recognize that since the absorber is usually not irradiated uniformly, it is therefore possible to construct an absorber of thermally isolated segments, circulate the fluid in sequence from low to high irradiance segments, and reduce loss by improving effective concentration. This procedure works even for ideal concentrators, without violating Winston's theorem. Two equivalent CPC collectors with single and segmented absorber were constructed and compared under actual operating conditions. The results showed that the daily thermal efficiency of the collector with segmented absorber is higher (about 13%) than that of the collector with nonsegmented absorber.

  11. Methods for absorbing neutrons

    DOEpatents

    Guillen, Donna P [Idaho Falls, ID; Longhurst, Glen R [Idaho Falls, ID; Porter, Douglas L [Idaho Falls, ID; Parry, James R [Idaho Falls, ID

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  12. Cold injuries.

    PubMed

    Kruse, R J

    1995-01-01

    There are two categories of cold injury. The first is hypothermia, which is a systemic injury to cold, and the second is frostbite, which is a local injury. Throughout history, entire armies, from George Washington to the Germans on the Russian Front in World War II, have fallen prey to prolonged cold exposure. Cold injury is common and can occur in all seasons if ambient temperature is lower than the core body temperature. In the 1985 Boston Marathon, even though it was 76 degrees and sunny, there were 75 runners treated for hypothermia. In general, humans adapt poorly to cold exposure. Children are at particular risk because of their relatively greater surface area/body mass ratio, causing them to cool even more rapidly than adults. Because of this, the human's best defense against cold injury is to limit his/her exposure to cold and to dress appropriately. If cold injury has occurred and is mild, often simple passive rewarming such as dry blankets and a warm room are sufficient treatment.

  13. Advanced neutron absorber materials

    DOEpatents

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  14. SHOCKED SUPERWINDS FROM THE z {approx} 2 CLUMPY STAR-FORMING GALAXY, ZC406690

    SciTech Connect

    Newman, Sarah F.; Genzel, Reinhard; Shapiro Griffin, Kristen; Davies, Ric; Foerster-Schreiber, Natascha M.; Tacconi, Linda J.; Kurk, Jaron; Wuyts, Stijn; Genel, Shy; Buschkamp, Peter; Eisenhauer, Frank; Lutz, Dieter; Lilly, Simon J.; Carollo, C. Marcella; Renzini, Alvio; Mancini, Chiara; Bouche, Nicolas; Burkert, Andreas; Cresci, Giovanni; Hicks, Erin; and others

    2012-06-20

    We have obtained high-resolution data of the z {approx} 2 ring-like, clumpy star-forming galaxy (SFG) ZC406690 using the VLT/SINFONI with adaptive optics (in K band) and in seeing-limited mode (in H and J bands). Our data include all of the main strong optical emission lines: [O II], [O III], H{alpha}, H{beta}, [N II], and [S II]. We find broad, blueshifted H{alpha} and [O III] emission line wings in the spectra of the galaxy's massive, star-forming clumps ({sigma} {approx} 85 km s{sup -1}) and even broader wings (up to 70% of the total H{alpha} flux, with {sigma} {approx} 290 km s{sup -1}) in regions spatially offset from the clumps by {approx}2 kpc. The broad emission likely originates from large-scale outflows with mass outflow rates from individual clumps that are 1-8 Multiplication-Sign the star formation rate (SFR) of the clumps. Based on emission line ratio diagnostics ([N II]/H{alpha} and [S II]/H{alpha}) and photoionization and shock models, we find that the emission from the clumps is due to a combination of photoionization from the star-forming regions and shocks generated in the outflowing component, with 5%-30% of the emission deriving from shocks. In terms of the ionization parameter (6 Multiplication-Sign 10{sup 7} to 10{sup 8} cm s{sup -1}, based on both the SFR and the O{sub 32} ratio), density (local electron densities of 300-1800 cm{sup -3} in and around the clumps, and ionized gas column densities of 1200-8000 M{sub Sun }pc{sup -2}), and SFR (10-40 M{sub Sun} yr{sup -1}), these clumps more closely resemble nuclear starburst regions of local ultraluminous infrared galaxies and dwarf irregulars than H II regions in local galaxies. However, the star-forming clumps are not located in the nucleus as in local starburst galaxies but instead are situated in a ring several kpc from the center of their high-redshift host galaxy, and have an overall disk-like morphology. The two brightest clumps are quite different in terms of their internal properties

  15. Shocked Superwinds from the z ~ 2 Clumpy Star-forming Galaxy, ZC406690

    NASA Astrophysics Data System (ADS)

    Newman, Sarah F.; Shapiro Griffin, Kristen; Genzel, Reinhard; Davies, Ric; Förster-Schreiber, Natascha M.; Tacconi, Linda J.; Kurk, Jaron; Wuyts, Stijn; Genel, Shy; Lilly, Simon J.; Renzini, Alvio; Bouché, Nicolas; Burkert, Andreas; Cresci, Giovanni; Buschkamp, Peter; Carollo, C. Marcella; Eisenhauer, Frank; Hicks, Erin; Lutz, Dieter; Mancini, Chiara; Naab, Thorsten; Peng, Yingjie; Vergani, Daniela

    2012-06-01

    We have obtained high-resolution data of the z ~ 2 ring-like, clumpy star-forming galaxy (SFG) ZC406690 using the VLT/SINFONI with adaptive optics (in K band) and in seeing-limited mode (in H and J bands). Our data include all of the main strong optical emission lines: [O II], [O III], Hα, Hβ, [N II], and [S II]. We find broad, blueshifted Hα and [O III] emission line wings in the spectra of the galaxy's massive, star-forming clumps (σ ~ 85 km s-1) and even broader wings (up to 70% of the total Hα flux, with σ ~ 290 km s-1) in regions spatially offset from the clumps by ~2 kpc. The broad emission likely originates from large-scale outflows with mass outflow rates from individual clumps that are 1-8× the star formation rate (SFR) of the clumps. Based on emission line ratio diagnostics ([N II]/Hα and [S II]/Hα) and photoionization and shock models, we find that the emission from the clumps is due to a combination of photoionization from the star-forming regions and shocks generated in the outflowing component, with 5%-30% of the emission deriving from shocks. In terms of the ionization parameter (6 × 107 to 108 cm s-1, based on both the SFR and the O32 ratio), density (local electron densities of 300-1800 cm-3 in and around the clumps, and ionized gas column densities of 1200-8000 M ⊙pc-2), and SFR (10-40 M ⊙ yr-1), these clumps more closely resemble nuclear starburst regions of local ultraluminous infrared galaxies and dwarf irregulars than H II regions in local galaxies. However, the star-forming clumps are not located in the nucleus as in local starburst galaxies but instead are situated in a ring several kpc from the center of their high-redshift host galaxy, and have an overall disk-like morphology. The two brightest clumps are quite different in terms of their internal properties, energetics, and relative ages, and thus we are given a glimpse at two different stages in the formation and evolution of rapidly star-forming giant clumps at high

  16. A total and polarized infrared flux view of the AGN clumpy torus

    NASA Astrophysics Data System (ADS)

    Lopez Rodriguez, Enrique

    2013-12-01

    Magnetohydrodynamical theories consider the torus of Active Galactic Nuclei (AGN) to be part of an outflow wind moving away from the central engine. In this framework, the torus is a particular region of the wind, where dusty and optically thick clouds are formed. The outflows are strongly related to the accretion rate and magnetic field strength, which play an important role in the creation, morphology and evolution of the torus. Through infrared (IR) imaging and polarimetry observations, this dissertation (1) searches for signatures of dusty tori in low-luminosity AGN (LLAGN); (2) explores the role and strength of magnetic field in the torus; and (3) investigates the nucleus of radio-loud AGN. Recent theoretical models predicted that LLAGN do not host a Seyfert-like torus, since low-luminosities (<1042 erg s-1 ) cannot sustain the required outflow rate. High-spatial resolution mid-IR (MIR) imaging and nuclear spectral energy distribution of 22 LLAGN reveals different IR characteristics by dividing the sample in terms of the Eddington ratio. These galaxies show a diversity of nuclear morphologies and have a high MIR/X-ray luminosity ratio compared to higher-luminosity AGN. Star formation, jets and/or truncated accretion disk can explain the MIR excess. Although several models have been made to account for the outflowing dusty winds from the central engine, the magnetic field strength at the position of the torus remains poorly characterized. Through a novel study using near-IR polarimetry, the magnetic field strength in the clumpy torus was estimated. Specifically, if paramagnetic alignment is assumed in the dusty clouds of the torus, the magnetic field strength of the torus of IC5063 is estimated to be in the range of 12--128 mG. Alternatively, Chandrasekhar-Fermi method suggests a lower-limit magnetic field strength of 13 mG. For the archetypical radio-loud AGN, Cygnus A, MIR polarimetry using CanariCam on the 10.4-m Gran Telescopio de Canarias revealed a high

  17. The evidence for clumpy accretion in the Herbig Ae star HR 5999

    NASA Technical Reports Server (NTRS)

    Perez, M. R.; Grady, C. A.; The, P. S.

    1993-01-01

    Analysis of IUE high- and low-dispersion spectra of the young Herbig Ae star HR 5999 (HD 144668) covering 1978-1992 revealed dramatic changes in the Mg II h and k (2795.5, 2802.7 A) emission profiles, changes in the column density and distribution in radial velocity of accreting gas, and flux in the Ly(alpha), O I, and C IV emission lines, which are correlated with the UV excess luminosity. Variability in the spectral type inferred from the UV spectral energy distribution, ranging from A5 IV-III in high state to A7 III in the low state, was also observed. The trend of earlier inferred spectral type with decreasing wavelength and with increasing UV continuum flux has previously been noted as a signature of accretion disks in lower mass pre-main sequence stars (PMS) and in systems undergoing FU Orionis-type outbursts. Our data represent the first detection of similar phenomena in an intermediate mass (M greater than or equal to 2 solar mass) PMS star. Recent IUE spectra show gas accreting toward the star with velocities as high as plus 300 km/s, much as is seen toward beta Pic, and suggest that we also view this system through the debris disk. The absence of UV lines with the rotational broadening expected given the optical data (A7 IV, V sini=180 plus or minus 20 km/s for this system) also suggests that most of the UV light originates in the disk, even in the low continuum state. The dramatic variability in the column density of accreting gas, is consistent with clumpy accretion, such as has been observed toward beta Pic, is a hallmark of accretion onto young stars, and is not restricted to the clearing phase, since detectable amounts of accretion are present for stars with 0.5 Myr less than t(sub age) less than 2.8 Myr. The implications for models of beta Pic and similar systems are briefly discussed.

  18. Multispectral metamaterial absorber.

    PubMed

    Grant, J; McCrindle, I J H; Li, C; Cumming, D R S

    2014-03-01

    We present the simulation, implementation, and measurement of a multispectral metamaterial absorber (MSMMA) and show that we can realize a simple absorber structure that operates in the mid-IR and terahertz (THz) bands. By embedding an IR metamaterial absorber layer into a standard THz metamaterial absorber stack, a narrowband resonance is induced at a wavelength of 4.3 μm. This resonance is in addition to the THz metamaterial absorption resonance at 109 μm (2.75 THz). We demonstrate the inherent scalability and versatility of our MSMMA by describing a second device whereby the MM-induced IR absorption peak frequency is tuned by varying the IR absorber geometry. Such a MSMMA could be coupled with a suitable sensor and formed into a focal plane array, enabling multispectral imaging.

  19. Submillimeter and far infrared line observations of M17 SW: A clumpy molecular cloud penetrated by UV radiation

    NASA Technical Reports Server (NTRS)

    Stutzki, J.; Stacey, G. J.; Genzel, R.; Harris, A. I.; Jaffe, d. T.; Lugten, J. B.

    1987-01-01

    Millimeter, submillimeter, and far infrared spectroscopic observations of the M17 SW star formation region are discussed. The results require the molecular cloud near the interface to be clumpy or filamentary. As a consequence, far ultraviolet radiation from the central OB stellar cluster can penetrate into the dense molecular cloud to a depth of several pc, thus creating bright and extended (CII) emission from the photodissociated surfaces of dense atomic and molecular clumps or sheets. The extended (CII) emission throughout the molecular cloud SW of the M17 complex has a level 20 times higher than expected from a single molecular cloud interface exposed to an ultraviolet radiation field typical of the solar neighborhood. This suggests that the molecular cloud as a whole is penetrated by ultraviolet radiation and has a clumpy or filamentary structure. The number of B stars expected to be embedded in the M17 molecular cloud probably can provide the UV radiation necessary for the extended (CII) emission. Alternatively, the UV radiation could be external, if the interstellar radiation in the vicinity of M17 is higher than in the solar neighborhood.

  20. Cold intolerance

    MedlinePlus

    Some causes of cold intolerance are: Anemia Anorexia nervosa Blood vessel problems, such as Raynaud phenomenon Chronic severe illness General poor health Underactive thyroid ( hypothyroidism ) Problem with the hypothalamus (a part ...

  1. Internal absorber solar collector

    DOEpatents

    Sletten, Carlyle J.; Herskovitz, Sheldon B.; Holt, F. S.; Sletten, E. J.

    1981-01-01

    Thin solar collecting panels are described made from arrays of small rod collectors consisting of a refracting dielectric rod lens with an absorber imbedded within it and a reflecting mirror coated on the back side of the dielectric rod. Non-tracking collector panels on vertical walls or roof tops receive approximately 90% of solar radiation within an acceptance zone 60.degree. in elevation angle by 120.degree. or more in the azimuth sectors with a collector concentration ratio of approximately 3.0. Miniaturized construction of the circular dielectric rods with internal absorbers reduces the weight per area of glass, plastic and metal used in the collector panels. No external parts or insulation are needed as heat losses are low due to partial vacuum or low conductivity gas surrounding heated portions of the collector. The miniature internal absorbers are generally made of solid copper with black selective surface and the collected solar heat is extracted at the collector ends by thermal conductivity along the absorber rods. Heat is removed from end fittings by use of liquid circulants. Several alternate constructions are provided for simplifying collector panel fabrication and for preventing the thermal expansion and contraction of the heated absorber or circulant tubes from damaging vacuum seals. In a modified version of the internal absorber collector, oil with temperature dependent viscosity is pumped through a segmented absorber which is now composed of closely spaced insulated metal tubes. In this way the circulant is automatically diverted through heated portions of the absorber giving higher collector concentration ratios than theoretically possible for an unsegmented absorber.

  2. Lipid-absorbing Polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.; Wallace, C. J.

    1973-01-01

    The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

  3. Electromagnetic power absorber

    NASA Technical Reports Server (NTRS)

    Iwasaki, R. S. (Inventor)

    1979-01-01

    A structure is presented with a surface portion of dielectric material which passes electromagnetic radiation and with a portion below the surface which includes material that absorbs the radiation, the face of the structure being formed with numerous steep ridges. The steepness of the dielectric material results in a high proportion of the electromagnetic energy passing through the surface for absorption by the absorbing material under the surface. A backing of aluminum or other highly heat-conductive and reflective material lies under the face and has very steep protuberances supporting the absorbing and dielectric materials.

  4. COLD WATER VAPOR IN THE BARNARD 5 MOLECULAR CLOUD

    SciTech Connect

    Wirström, E. S.; Persson, C. M.; Charnley, S. B.; Cordiner, M. A.; Buckle, J. V.; Takakuwa, S.

    2014-06-20

    After more than 30 yr of investigations, the nature of gas-grain interactions at low temperatures remains an unresolved issue in astrochemistry. Water ice is the dominant ice found in cold molecular clouds; however, there is only one region where cold (∼10 K) water vapor has been detected—L1544. This study aims to shed light on ice desorption mechanisms under cold cloud conditions by expanding the sample. The clumpy distribution of methanol in dark clouds testifies to transient desorption processes at work—likely to also disrupt water ice mantles. Therefore, the Herschel HIFI instrument was used to search for cold water in a small sample of prominent methanol emission peaks. We report detections of the ground-state transition of o-H{sub 2}O (J = 1{sub 10}-1{sub 01}) at 556.9360 GHz toward two positions in the cold molecular cloud, Barnard 5. The relative abundances of methanol and water gas support a desorption mechanism which disrupts the outer ice mantle layers, rather than causing complete mantle removal.

  5. Cold Water Vapor in the Barnard 5 Molecular Cloud

    NASA Technical Reports Server (NTRS)

    Wirstrom, E. S.; Charnley, S. B.; Persson, C. M.; Buckle, J. V.; Cordiner, M. A.; Takakuwa, S.

    2014-01-01

    After more than 30 yr of investigations, the nature of gas-grain interactions at low temperatures remains an unresolved issue in astrochemistry. Water ice is the dominant ice found in cold molecular clouds; however, there is only one region where cold ((is) approximately 10 K) water vapor has been detected-L1544. This study aims to shed light on ice desorption mechanisms under cold cloud conditions by expanding the sample. The clumpy distribution of methanol in dark clouds testifies to transient desorption processes at work-likely to also disrupt water ice mantles. Therefore, the Herschel HIFI instrument was used to search for cold water in a small sample of prominent methanol emission peaks. We report detections of the ground-state transition of o-H2O (J = 110-101) at 556.9360 GHz toward two positions in the cold molecular cloud, Barnard 5. The relative abundances of methanol and water gas support a desorption mechanism which disrupts the outer ice mantle layers, rather than causing complete mantle removal.

  6. "Smart" Electromechanical Shock Absorber

    NASA Technical Reports Server (NTRS)

    Stokes, Lebarian; Glenn, Dean C.; Carroll, Monty B.

    1989-01-01

    Shock-absorbing apparatus includes electromechanical actuator and digital feedback control circuitry rather than springs and hydraulic damping as in conventional shock absorbers. Device not subject to leakage and requires little or no maintenance. Attenuator parameters adjusted in response to sensory feedback and predictive algorithms to obtain desired damping characteristic. Device programmed to decelerate slowly approaching vehicle or other large object according to prescribed damping characteristic.

  7. Cold injuries.

    PubMed

    Long, William B; Edlich, Richard F; Winters, Kathryne L; Britt, L D

    2005-01-01

    Exposure to cold can produce a variety of injuries that occur as a result of man's inability to adapt to cold. These injuries can be divided into localized injury to a body part, systemic hypothermia, or a combination of both. Body temperature may fall as a result of heat loss by radiation, evaporation, conduction, and convection. Hypothermia or systemic cold injury occurs when the core body temperature has decreased to 35 degrees C (95 degrees F) or less. The causes of hypothermia are either primary or secondary. Primary, or accidental, hypothermia occurs in healthy individuals inadequately clothed and exposed to severe cooling. In secondary hypothermia, another illness predisposes the individual to accidental hypothermia. Hypothermia affects multiple organs with symptoms of hypothermia that vary according to the severity of cold injury. The diagnosis of hypothermia is easy if the patient is a mountaineer who is stranded in cold weather. However, it may be more difficult in an elderly patient who has been exposed to a cold environment. In either case, the rectal temperature should be checked with a low-reading thermometer. The general principals of prehospital management are to (1) prevent further heat loss, (2) rewarm the body core temperature in advance of the shell, and (3) avoid precipitating ventricular fibrillation. There are two general techniques of rewarming--passive and active. The mechanisms of peripheral cold injury can be divided into phenomena that affect cells and extracellular fluids (direct effects) and those that disrupt the function of the organized tissue and the integrity of the circulation (indirect effects). Generally, no serious damage is seen until tissue freezing occurs. The mildest form of peripheral cold injury is frostnip. Chilblains represent a more severe form of cold injury than frostnip and occur after exposure to nonfreezing temperatures and damp conditions. Immersion (trench) foot, a disease of the sympathetic nerves and blood

  8. Cold urticaria.

    PubMed

    Claudy, A

    2001-11-01

    Cold urticaria is one form of urticaria that may be associated with other forms of physical urticarias. Frequency is generally estimated at two or three per 100. The triggering effect of cold is found at history taking in most of the cases. The urticaria is usually superficial, and more rarely associated with deep and/or mucosal urticaria. The diagnosis is based on history taking and the ice cube test. An exhaustive search for an etiologic factor is often unfruitful, and the presence of a cryopathy should lead to a complete work-up. Therapy of cold urticaria may prove to be difficult. In patients with secondary cold urticaria, underlying disease must be treated in order to resolve the skin symptoms. H1-antihistamines can be used but the clinical responses are highly variable. Short-time treatment with low concentration corticosteroids suppresses the symptoms only partially and temporarily. In patients who do not respond to previous treatments, induction of cold tolerance may be proposed but the procedure is difficult to carry out in daily life over an extended period. Key word: cryoglobulins.

  9. COLD TRAP

    DOEpatents

    Milleron, N.

    1963-03-12

    An improved linear-flow cold trap is designed for highvacuum applications such as mitigating back migration of diffusion pump oil moiecules. A central pot of liquid nitrogen is nested within and supported by a surrounding, vertical, helical coil of metai sheet, all enveloped by a larger, upright, cylindrical, vacuum vessel. The vertical interstices between successive turns of the coil afford lineal, axial, high-vacuum passages between open mouths at top and bottom of said vessel, while the coil, being cold by virtue of thermal contact of its innermost turn with the nitrogen pot, affords expansive proximate condensation surfaces. (AEC)

  10. Starburst galaxies in the COSMOS field: clumpy star-formation at redshift 0 < z < 0.5

    NASA Astrophysics Data System (ADS)

    Hinojosa-Goñi, R.; Muñoz-Tuñón, C.; Méndez-Abreu, J.

    2016-08-01

    Context. At high redshift, starburst galaxies present irregular morphologies with 10-20% of their star formation occurring in giant clumps. These clumpy galaxies are considered the progenitors of local disk galaxies. To understand the properties of starbursts at intermediate and low redshift, it is fundamental to track their evolution and the possible link with the systems at higher z. Aims: We present an extensive, systematic, and multiband search and analysis of the starburst galaxies at redshift (0 < z < 0.5) in the COSMOS field, as well as detailed characteristics of their star-forming clumps by using Hubble Space Telescope/Advance Camera for Surveys (HST/ACS) images. Methods: The starburst galaxies are identified using a tailor-made intermediate-band color excess selection, tracing the simultaneous presence of Hα and [OIII] emission lines in the galaxies. Our methodology uses previous information from the zCOSMOS spectral database to calibrate the color excess as a function of the equivalent width of both spectral lines. This technique allows us to identify 220 starburst galaxies at redshift 0 < z < 0.5 using the SUBARU intermediate-band filters. Combining the high spatial resolution images from the HST/ACS with ground-based multi-wavelength photometry, we identify and parametrize the star-forming clumps in every galaxy. Their principal properties, sizes, masses, and star formation rates are provided. Results: The mass distribution of the starburst galaxies is remarkably similar to that of the whole galaxy sample with a peak around M/M⊙ ~ 2 × 108 and only a few galaxies with M/M⊙ > 1010. We classify galaxies into three main types, depending on their HST morphology: single knot (Sknot), single star-forming knot plus diffuse light (Sknot+diffuse), and multiple star-forming knots (Mknots/clumpy) galaxy. We found a fraction of Mknots/clumpy galaxy fclumpy = 0.24 considering out total sample of starburst galaxies up to z ~ 0.5. The individual star

  11. Unidirectional perfect absorber

    PubMed Central

    Jin, L.; Wang, P.; Song, Z.

    2016-01-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices. PMID:27615125

  12. Shock absorber servicing tool

    NASA Technical Reports Server (NTRS)

    Koepler, Jack L. (Inventor); Hill, Robert L. (Inventor)

    1981-01-01

    A tool to assist in the servicing of a shock absorber wherein the shock absorber is constructed of a pair of aligned gas and liquid filled chambers. Each of the chambers is separated by a movable separator member. Maximum efficiency of the shock absorber is achieved in the locating of a precise volume of gas within the gas chamber and a precise volume of liquid within the liquid chamber. The servicing tool of this invention employs a rod which is to connect with the separator and by observation of the position of the rod with respect to the gauge body, the location of the separator is ascertained even though it is not directly observable.

  13. Unidirectional perfect absorber

    NASA Astrophysics Data System (ADS)

    Jin, L.; Wang, P.; Song, Z.

    2016-09-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices.

  14. Cold Sores

    MedlinePlus

    ... causes oral herpes, or cold sores. Type 1 herpes virus infects more than half of the U.S. population by the time they reach their 20s. Type 2 usually affects the genital area Some people have no symptoms from the ...

  15. Infrared bolometers with silicon nitride micromesh absorbers

    NASA Technical Reports Server (NTRS)

    Bock, J. J.; Turner, A. D.; DelCastillo, H. M.; Beeman, J. W.; Lange, A. E.; Mauskopf, P. D.

    1996-01-01

    Sensitive far infrared and millimeter wave bolometers fabricated from a freestanding membrane of low stress silicon nitride are reported. The absorber, consisting of a metallized silicon nitride micromesh thermally isolated by radial legs of silicon nitride, is placed in an integrating cavity to efficiently couple to single mode or multiple mode infrared radiation. This structure provides low heat capacity, low thermal conduction and minimal cross section to energetic particles. A neutron transmutation doped Ge thermister is bump bonded to the center of the device and read out with evaporated Cr-Au leads. The limiting performance of the micromesh absorber is discussed and the recent results obtained from a 300 mK cold stage are summarized.

  16. Shock Absorbing System

    NASA Astrophysics Data System (ADS)

    1982-01-01

    A lightweight, inexpensive shock-absorbing system, developed by Langley Research Center 20 years ago, is now in service as safety device for an automated railway at Duke University Medical Center. The transportation system travels at about 25 miles per hour, carrying patients, visitors, staff and cargo. At the end of each guideway of the system are "frangible," (breakable) tube "buffers." If a slowing car fails to make a complete stop at the terminal, it would bump and shatter the tubes, absorbing energy that might otherwise jolt the passengers or damage the vehicle.

  17. Solar concentrator/absorber

    NASA Technical Reports Server (NTRS)

    Von Tiesenhausen, G. F.

    1976-01-01

    Collector/energy converter, consisting of dual-slope optical concentrator and counterflow thermal energy absorber, is attached to multiaxis support structure. Efficient over wide range of illumination levels, device may be used to generate high temperature steam, serve as solar powered dryer, or power absorption cycle cooler.

  18. Neutron Absorbing Alloys

    SciTech Connect

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  19. Shock Absorbing Helmets

    NASA Technical Reports Server (NTRS)

    1978-01-01

    This paper presents a description of helmets used by football players that offer three times the shock-absorbing capacity of earlier types. An interior padding for the helmets, composed of Temper Foam, first used by NASA's Ames Research Center in the design of aircraft seats is described.

  20. Hot, Cold, and Really Cold.

    ERIC Educational Resources Information Center

    Leyden, Michael

    1997-01-01

    Describes a physics experiment investigating temperature prediction and the relationship between the physical properties of heat units, melting, dissolving, states of matter, and energy loss. Details the experimental setup, which requires hot and cold water, a thermometer, and ice. Notes that the experiment employs a deliberate counter-intuitive…

  1. Metasurface Broadband Solar Absorber

    PubMed Central

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  2. Metasurface Broadband Solar Absorber

    DOE PAGES

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; ...

    2016-02-01

    Here, we demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Moreover, our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributionsmore » to elucidate how the absorption occurs within the metasurface structure.« less

  3. Metasurface Broadband Solar Absorber

    SciTech Connect

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    Here, we demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Moreover, our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

  4. Ionized Absorbers in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  5. Apollo couch energy absorbers

    NASA Technical Reports Server (NTRS)

    Wesselski, C. J.; Drexel, R. E.

    1972-01-01

    Load attenuators for the Apollo spacecraft crew couch and its potential applications are described. Energy absorption is achieved through friction and cyclic deformation of material. In one concept, energy absorption is accomplished by rolling a compressed ring of metal between two surfaces. In another concept, energy is absorbed by forcing a plastically deformed washer along a rod. Among the design problems that had to be solved were material selection, fatigue life, ring slippage, lubrication, and friction loading.

  6. COLD TRAPS

    DOEpatents

    Thompson, W.I.

    1958-09-30

    A cold trap is presented for removing a condensable component from a gas mixture by cooling. It consists of a shell, the exterior surface of which is chilled by a refrigerant, and conductive fins welded inside the shell to condense the gas, and distribute the condensate evenly throughout the length of the trap, so that the trap may function until it becomes completely filled with the condensed solid. The contents may then be removed as either a gas or as a liquid by heating the trap. This device has particuinr use as a means for removing uranium hexafluoride from the gaseous diffusion separation process during equipment breakdown and repair periods.

  7. The Multi-Layer Variable Absorbers in NGC 1365 Revealed by XMM-Newton and NuSTAR

    NASA Technical Reports Server (NTRS)

    Rivers, E.; Risaliti, G.; Walton, D. J.; Harrison, F.; Arevalo, P.; Baur, F. E.; Boggs, S. E.; Brenneman, L. W.; Brightman, M.; Zhang, W. W.

    2015-01-01

    Between 2012 July and 2013 February, NuSTAR and XMM-Newton performed four long-look joint observations of the type 1.8 Seyfert, NGC 1365. We have analyzed the variable absorption seen in these observations in order to characterize the geometry of the absorbing material. Two of the observations caught NGC 1365 in an unusually low absorption state, revealing complexity in the multi-layer absorber that had previously been hidden. We find the need for three distinct zones of neutral absorption in addition to the two zones of ionized absorption and the Compton-thick torus previously seen in this source. The most prominent absorber is likely associated with broad-line region clouds with column densities of around approximately 10 (sup 23) per square centimeter and a highly clumpy nature as evidenced by an occultation event in 2013 February. We also find evidence of a patchy absorber with a variable column around approximately 10 (sup 22) per square centimeter and a line-of-sight covering fraction of 0.3-0.9, which responds directly to the intrinsic source flux, possibly due to a wind geometry. A full-covering, constant absorber with a low column density of approximately 1 by 10 (sup 22) per square centimeter is also present, though the location of this low density haze is unknown.

  8. The Multi-layer Variable Absorbers in NGC 1365 Revealed by XMM-Newton and NuSTAR

    NASA Astrophysics Data System (ADS)

    Rivers, E.; Risaliti, G.; Walton, D. J.; Harrison, F.; Arévalo, P.; Baur, F. E.; Boggs, S. E.; Brenneman, L. W.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Fürst, F.; Hailey, C. J.; Hickox, R. C.; Marinucci, A.; Reeves, J.; Stern, D.; Zhang, W. W.

    2015-05-01

    Between 2012 July and 2013 February, NuSTAR and XMM-Newton performed four long-look joint observations of the type 1.8 Seyfert, NGC 1365. We have analyzed the variable absorption seen in these observations in order to characterize the geometry of the absorbing material. Two of the observations caught NGC 1365 in an unusually low absorption state, revealing complexity in the multi-layer absorber that had previously been hidden. We find the need for three distinct zones of neutral absorption in addition to the two zones of ionized absorption and the Compton-thick torus previously seen in this source. The most prominent absorber is likely associated with broad-line region clouds with column densities of around ˜1023 cm-2 and a highly clumpy nature as evidenced by an occultation event in 2013 February. We also find evidence of a patchy absorber with a variable column around ˜1022 cm-2 and a line-of-sight covering fraction of 0.3-0.9, which responds directly to the intrinsic source flux, possibly due to a wind geometry. A full-covering, constant absorber with a low column density of ˜1 × 1022 cm-2 is also present, though the location of this low density haze is unknown.

  9. Absorber for terahertz radiation management

    SciTech Connect

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  10. Cold Urticaria

    PubMed Central

    Wasserman, Stephen I.; Soter, Nicholas A.; Center, David M.; Austen, K. Frank

    1977-01-01

    Sera were obtained from the venous effluents of cold-challenged arms of patients with idiopathic cold urticaria without plasma or serum cryoproteins; these sera exhibited increased neutrophil chemotactic activity without alterations of the complement system. A two- to fourfold augmentation of the base-line neutrophil chemotactic activity of serum from the immersed extremity began within 1 min, peaked at 2 min, and returned to base-line levels within 15 min, whereas there was no change in the serum chemotactic activity in the control arm. The augmented chemotactic activity in the serum specimens from the challenged arm of each patient appeared in a high molecular-weight region, as assessed by the difference in activity recovered after Sephadex G-200 gel filtration of the paired lesional and control specimens. Sequential purification of this high molecular-weight activity by anion- and cation-exchange chromatography revealed a single peak of activity at both steps. The partially purified material continued to exhibit a high molecular weight, being excluded on Sepharose 4B, and had a neutral isoelectric point. The partially purified material showed a preferential chemotactic activity for neutrophilic polymorphonuclear leukocytes, required a gradient for expression of this function, and exhibited a capacity to deactivate this cell type. This active principle, termed high molecular-weight neutrophil chemotactic factor, exhibited a time-course of release that could be superimposed upon that of histamine and the low molecular-weight eosinophil chemotactic factor and may represent another mast cell-derived mediator. PMID:874083

  11. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  12. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  13. Submillimeter and far-infrared line observations of M17 SW - A clumpy molecular cloud penetrated by ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Stutzki, J.; Genzel, R.; Harris, A. I.; Stacey, G. J.; Jaffe, D. T.

    1988-01-01

    Millimeter, submillimeter, and far-IR spectroscopic observations of the M17 SW star formation region are reported. Strong forbidden C II 158 micron and CO J = 7 - 6 line emission arises in an H II region/molecular cloud interface of several pc thickness. Weaker forbidden C II emission appears to be extended over 15 pc throughout the molecular cloud. CO J = 14 - 13 and forbidden O I 145 micron spectra indicate high temperatures and densities for both molecular and atomic gas in the interface. The results require the molecular cloud near the interface to be clumpy or filamentary. The extended forbidden C II emission throughout the molecular cloud has a level around 20 times higher than expected from a single molecular cloud interface exposed to an ultraviolet radiation field typical of the solar neighborhood. The high gas temperature of molecular material in the UV-illuminated interface region suggests that CO self-shielding and heating of CO by photoelectrons are important.

  14. THE THICK DISKS OF SPIRAL GALAXIES AS RELICS FROM GAS-RICH, TURBULENT, CLUMPY DISKS AT HIGH REDSHIFT

    SciTech Connect

    Bournaud, Frederic; Martig, Marie; Elmegreen, Bruce G.

    2009-12-10

    The formation of thick stellar disks in spiral galaxies is studied. Simulations of gas-rich young galaxies show formation of internal clumps by gravitational instabilities, clump coalescence into a bulge, and disk thickening by strong stellar scattering. The bulge and thick disks of modern galaxies may form this way. Simulations of minor mergers make thick disks too, but there is an important difference. Thick disks made by internal processes have a constant scale height with galactocentric radius, but thick disks made by mergers flare. The difference arises because in the first case, perpendicular forcing and disk-gravity resistance are both proportional to the disk column density, so the resulting scale height is independent of this density. In the case of mergers, perpendicular forcing is independent of the column density and the low-density regions get thicker; the resulting flaring is inconsistent with observations. Late-stage gas accretion and thin-disk growth are shown to preserve the constant scale heights of thick disks formed by internal evolution. These results reinforce the idea that disk galaxies accrete most of their mass smoothly and acquire their structure by internal processes, in particular through turbulent and clumpy phases at high redshift.

  15. Solar radiation absorbing material

    DOEpatents

    Googin, John M.; Schmitt, Charles R.; Schreyer, James M.; Whitehead, Harlan D.

    1977-01-01

    Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a microporous carbon article by controlling the pore size. A thermally conductive substrate is provided with a solar selective surface by adhering an array of carbon particles in a suitable binder to the substrate, a majority of said particles having diameters within the range of about 0.2-10 microns.

  16. Liquid Cryogen Absorber for MICE

    SciTech Connect

    Baynham, D.E.; Bish, P.; Bradshaw, T.W.; Cummings, M.A.; Green,M.A.; Ishimoto, S.; Ivaniouchenkov, I.; Lau, W.; Yang, S.Q.; Zisman, M.S.

    2005-08-20

    The Muon Ionization Cooling Experiment (MICE) will test ionization cooling of muons. In order to have effective ionization cooling, one must use an absorber that is made from a low-z material. The most effective low z materials for ionization cooling are hydrogen, helium, lithium hydride, lithium and beryllium, in that order. In order to measure the effect of material on cooling, several absorber materials must be used. This report describes a liquid-hydrogen absorber that is within a pair of superconducting focusing solenoids. The absorber must also be suitable for use with liquid helium. The following absorber components are discussed in this report; the absorber body, its heat exchanger, the hydrogen system, and the hydrogen safety. Absorber cooling and the thin windows are not discussed here.

  17. Cough & Cold Medicine Abuse

    MedlinePlus

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Cough & Cold Medicine Abuse KidsHealth > For Teens > Cough & Cold ... Someone Quit? Avoiding DXM Why Do People Use Cough and Cold Medicines to Get High? There's an ...

  18. Ferroelectrics based absorbing layers

    NASA Astrophysics Data System (ADS)

    Hao, Jianping; Sadaune, Véronique; Burgnies, Ludovic; Lippens, Didier

    2014-07-01

    We show that ferroelectrics-based periodic structure made of BaSrTiO3 (BST) cubes, arrayed onto a metal plate with a thin dielectric spacer film exhibit a dramatic enhancement of absorbance with value close to unity. The enhancement is found around the Mie magnetic resonance of the Ferroelectrics cubes with the backside metal layer stopping any transmitted waves. It also involves quasi-perfect impedance matching resulting in reflection suppression via simultaneous magnetic and electrical activities. In addition, it was shown numerically the existence of a periodicity optimum, which is explained from surface waves analysis along with trade-off between the resonance damping and the intrinsic loss of ferroelectrics cubes. An experimental verification in a hollow waveguide configuration with a good comparison with full-wave numerical modelling is at last reported by measuring the scattering parameters of single and dual BST cubes schemes pointing out coupling effects for densely packed structures.

  19. Dual broadband metamaterial absorber.

    PubMed

    Kim, Young Ju; Yoo, Young Joon; Kim, Ki Won; Rhee, Joo Yull; Kim, Yong Hwan; Lee, YoungPak

    2015-02-23

    We propose polarization-independent and dual-broadband metamaterial absorbers at microwave frequencies. This is a periodic meta-atom array consisting of metal-dielectric-multilayer truncated cones. We demonstrate not only one broadband absorption from the fundamental magnetic resonances but additional broadband absorption in high-frequency range using the third-harmonic resonance, by both simulation and experiment. In simulation, the absorption was over 90% in 3.93-6.05 GHz, and 11.64-14.55 GHz. The corresponding experimental absorption bands over 90% were 3.88-6.08 GHz, 9.95-10.46 GHz and 11.86-13.84 GHz, respectively. The origin of absorption bands was elucidated. Furthermore, it is independent of polarization angle owing to the multilayered circular structures. The design is scalable to smaller size for the infrared and the visible ranges.

  20. THz-metamaterial absorbers

    NASA Astrophysics Data System (ADS)

    Tuong Pham, Van; Park, J. W.; Vu, Dinh Lam; Zheng, H. Y.; Rhee, J. Y.; Kim, K. W.; Lee, Y. P.

    2013-03-01

    An ultrabroad-band metamaterial absorber was investigated in mid-IR regime based on a similar model in previous work. The high absorption of metamaterial was obtained in a band of 8-11.7 THz with energy loss distributed in SiO2, which is appropriate potentially for solar-cell applications. A perfect absorption peak was provided by using a sandwich structure with periodical anti-dot pattern in the IR region, getting closed to visible-band metamaterials. The dimensional parameters were examined for the corresponding fabrication. Invited talk at the 6th International Workshop on Advanced Materials Science and Nanotechnology, 30 October-2 November, 2012, Ha Long, Vietnam.

  1. Chaotic cold accretion on to black holes

    NASA Astrophysics Data System (ADS)

    Gaspari, M.; Ruszkowski, M.; Oh, S. Peng

    2013-07-01

    Bondi theory is often assumed to adequately describe the mode of accretion in astrophysical environments. However, the Bondi flow must be adiabatic, spherically symmetric, steady, unperturbed, with constant boundary conditions. Using 3D adaptive mesh refinement simulations, linking the 50 kpc to the sub-parsec (sub-pc) scales over the course of 40 Myr, we systematically relax the classic assumptions in a typical galaxy hosting a supermassive black hole. In the more realistic scenario, where the hot gas is cooling, while heated and stirred on large scales, the accretion rate is boosted up to two orders of magnitude compared with the Bondi prediction. The cause is the non-linear growth of thermal instabilities, leading to the condensation of cold clouds and filaments when tcool/tff ≲ 10. The clouds decouple from the hot gas, `raining' on to the centre. Subsonic turbulence of just over 100 km s-1 (M > 0.2) induces the formation of thermal instabilities, even in the absence of heating, while in the transonic regime turbulent dissipation inhibits their growth (tturb/tcool ≲ 1). When heating restores global thermodynamic balance, the formation of the multiphase medium is violent, and the mode of accretion is fully cold and chaotic. The recurrent collisions and tidal forces between clouds, filaments and the central clumpy torus promote angular momentum cancellation, hence boosting accretion. On sub-pc scales the clouds are channelled to the very centre via a funnel. In this study, we do not inject a fixed initial angular momentum, though vorticity is later seeded by turbulence. A good approximation to the accretion rate is the cooling rate, which can be used as subgrid model, physically reproducing the boost factor of 100 required by cosmological simulations, while accounting for the frequent fluctuations. Since our modelling is fairly general (turbulence/heating due to AGN feedback, galaxy motions, mergers, stellar evolution), chaotic cold accretion may be common in

  2. Cold confusion

    SciTech Connect

    Chapline, G.

    1989-07-01

    On March 23 two chemists, Martin Fleischmann and Stanley Pons startled the world with a press conference at the University of Utah where they announced that they had achieved nuclear fusion at room temperatures. As evidence they cited the production of ''excess'' amounts of heat in an electrochemical apparatus and observation of neutron production. While the production of heat in a chemical apparatus is not in itself unusual the observation of neutrons is certainly extraordinary. As it turned out, though, careful measurements of the neutron production in electrochemical apparatus similar to that used by Fleischmann and Pons carried out at dozens of other laboratories has shown that the neutron production fails by many orders of magnitude to support the assertion by Fleischmann and Pons that their discovery represents a new and cheap source of fusion power. In particular, independent measurements of the neutron production rate suggest that the actual rate of fusion energy production probably does not exceed 1 trillionth of a watt. This paper discusses the feasibility that cold fusion is actually being achieved. 7 refs.

  3. The young low-mass star ISO-Oph-50: extreme variability induced by a clumpy, evolving circumstellar disc

    NASA Astrophysics Data System (ADS)

    Scholz, Alexander; Mužić, Koraljka; Geers, Vincent

    2015-07-01

    ISO-Oph-50 is a young low-mass object in the ˜1 Myr old Ophiuchus star-forming region undergoing dramatic changes in its optical/near/mid-infrared brightness by 2-4 mag. We present new multi-band photometry and near-infrared spectra, combined with a synopsis of the existing literature data. Based on the spectroscopy, the source is confirmed as a mid-M dwarf, with evidence for ongoing accretion. The near-infrared light curves show large-scale variations, with 2-4 mag amplitude in the bands IJHK, with the object generally being bluer when faint. Near its brightest state, the object shows colour changes consistent with variable extinction of ΔAV ˜ 7 mag. High-cadence monitoring at 3.6 μm reveals quasi-periodic variations with a typical time-scale of 1-2 weeks. The best explanation for these characteristics is a low-mass star seen through circumstellar matter, whose complex variability is caused by changing inhomogeneities in the inner parts of the disc. When faint, the direct stellar emission is blocked; the near-infrared radiation is dominated by scattered light. When bright, the emission is consistent with a photosphere strongly reddened by circumstellar dust. Based on the available constraints, the inhomogeneities have to be located at or beyond ˜0.1 au distance from the star. If this scenario turns out to be correct, a major portion of the inner disc has to be clumpy, structured, and/or in turmoil. In its observational characteristics, this object resembles other types of young stellar objects with variability caused in the inner disc. Compared to other objects, however, ISO-Oph-50 is clearly an extreme case, given the large amplitude of the brightness and colour changes combined with the erratic behaviour. ISO-Oph-50 has been near its brightest state since 2013; further monitoring is highly encouraged.

  4. The dusty heart of nearby active galaxies. II. From clumpy torus models to physical properties of dust around AGN

    NASA Astrophysics Data System (ADS)

    Hönig, S. F.; Kishimoto, M.

    2010-11-01

    With the possibilities of high spatial resolution imaging and spectroscopy as well as infrared (IR) interferometry, the dusty environments (= “dusty torus”) of active galactic nuclei (AGN) are now in reach of observations. Following our Paper I on ground-based mid-IR spectro-photometry, we present an upgrade to our radiative transfer model of three-dimensional clumpy dust tori. The upgrade with respect to earlier work concerns an improved handling of the diffuse radiation field in the torus, which is approximated by a statistical approach. The models are presented as tools to translate classical and interferometric observations into characteristic properties of the dust distribution. We compare model spectral energy distributions (SEDs) for different chemical and grain-size compositions of the dust and find that clouds with standard interstellar matter (ISM) dust and optical depth τV ~ 50 appear in overall agreement with observed IR SEDs. By studying parameter dependencies, it is shown that type 1 AGN SEDs, in particular the mid-IR spectral index, can be used to constrain the radial dust cloud distribution power law index a, while other parameters are more difficult to assess using SEDs only. Interferometry adds important additional information for modeling when it is interpreted concurrently with the SED. Although type 2 AGN can in principle be used to constrain model parameters as well, obscuration effects make the analysis more ambiguous. We propose a simple, interferometry-based method to distinguish between “compact” and “extended” radial dust distributions without detailed modeling of the data and introduce a way to easily determine individual or sample average model parameters using the observed optical depth in the silicate feature and the mid-IR spectral index.

  5. Electrochemically regenerable carbon dioxide absorber

    NASA Technical Reports Server (NTRS)

    Woods, R. R.; Marshall, R. D.; Schubert, F. H.; Heppner, D. B.

    1979-01-01

    Preliminary designs were generated for two electrochemically regenerable carbon dioxide absorber concepts. Initially, an electrochemically regenerable absorption bed concept was designed. This concept incorporated the required electrochemical regeneration components in the absorber design, permitting the absorbent to be regenerated within the absorption bed. This hardware was identified as the electrochemical absorber hardware. The second hardware concept separated the functional components of the regeneration and absorption process. This design approach minimized the extravehicular activity component volume by eliminating regeneration hardware components within the absorber. The electrochemical absorber hardware was extensively characterized for major operating parameters such as inlet carbon dioxide partial pressure, process air flow rate, operational pressure, inlet relative humidity, regeneration current density and absorption/regeneration cycle endurance testing.

  6. Broadband patterned magnetic microwave absorber

    SciTech Connect

    Li, Wei; Wu, Tianlong; Wang, Wei; Guan, Jianguo; Zhai, Pengcheng

    2014-07-28

    It is a tough task to greatly improve the working bandwidth for the traditional flat microwave absorbers because of the restriction of available material parameters. In this work, a simple patterning method is proposed to drastically broaden the absorption bandwidth of a conventional magnetic absorber. As a demonstration, an ultra-broadband microwave absorber with more than 90% absorption in the frequency range of 4–40 GHz is designed and experimentally realized, which has a thin thickness of 3.7 mm and a light weight equivalent to a 2-mm-thick flat absorber. In such a patterned absorber, the broadband strong absorption is mainly originated from the simultaneous incorporation of multiple λ/4 resonances and edge diffraction effects. This work provides a facile route to greatly extend the microwave absorption bandwidth for the currently available absorbing materials.

  7. Liquid Hydrogen Absorber for MICE

    SciTech Connect

    Ishimoto, S.; Suzuki, S.; Yoshida, M.; Green, Michael A.; Kuno, Y.; Lau, Wing

    2010-05-30

    Liquid hydrogen absorbers for the Muon Ionization Cooling Experiment (MICE) have been developed, and the first absorber has been tested at KEK. In the preliminary test at KEK we have successfully filled the absorber with {approx}2 liters of liquid hydrogen. The measured hydrogen condensation speed was 2.5 liters/day at 1.0 bar. No hydrogen leakage to vacuum was found between 300 K and 20 K. The MICE experiment includes three AFC (absorber focusing coil) modules, each containing a 21 liter liquid hydrogen absorber made of aluminum. The AFC module has safety windows to separate its vacuum from that of neighboring modules. Liquid hydrogen is supplied from a cryocooler with cooling power 1.5 W at 4.2 K. The first absorber will be assembled in the AFC module and installed in MICE at RAL.

  8. Chaotic cold accretion on to black holes in rotating atmospheres

    NASA Astrophysics Data System (ADS)

    Gaspari, M.; Brighenti, F.; Temi, P.

    2015-07-01

    The fueling of black holes is one key problem in the evolution of baryons in the universe. Chaotic cold accretion (CCA) profoundly differs from classic accretion models, as Bondi and thin disc theories. Using 3D high-resolution hydrodynamic simulations, we now probe the impact of rotation on the hot and cold accretion flow in a typical massive galaxy. In the hot mode, with or without turbulence, the pressure-dominated flow forms a geometrically thick rotational barrier, suppressing the black hole accretion rate to ~1/3 of the spherical case value. When radiative cooling is dominant, the gas loses pressure support and quickly circularizes in a cold thin disk; the accretion rate is decoupled from the cooling rate, although it is higher than that of the hot mode. In the more common state of a turbulent and heated atmosphere, CCA drives the dynamics if the gas velocity dispersion exceeds the rotational velocity, i.e., turbulent Taylor number Tat< 1. Extended multiphase filaments condense out of the hot phase via thermal instability (TI) and rain toward the black hole, boosting the accretion rate up to 100 times the Bondi rate (Ṁ• ~ Ṁcool). Initially, turbulence broadens the angular momentum distribution of the hot gas, allowing the cold phase to condense with prograde or retrograde motion. Subsequent chaotic collisions between the cold filaments, clouds, and a clumpy variable torus promote the cancellation of angular momentum, leading to high accretion rates. As turbulence weakens (Tat > 1), the broadening of the distribution and the efficiency of collisions diminish, damping the accretion rate ∝ Tat-1, until the cold disk drives the dynamics. This is exacerbated by the increased difficulty to grow TI in a rotating halo. The simulated sub-Eddington accretion rates cover the range inferred from AGN cavity observations. CCA predicts inner flat X-ray temperature and r-1 density profiles, as recently discovered in M 87 and NGC 3115. The synthetic Hα images

  9. Cold energy

    SciTech Connect

    Wallace, John P.

    2015-12-04

    Deviations in Q for resonant superconducting radio frequency niobium accelerator cavities are generally correlated with resistivity loss mechanisms. Field dependent Qs are not well modeled by these classical loss mechanisms, but rather can represent a form of precision cavity surface thermometry. When the field dependent Q variation shows improvement with increasing B field level the classical treatment of this problem is inadequate. To justify this behavior hydrogen as a ubiquitous impurity in niobium, which creates measurable property changes, even at very low concentrations is typically considered the cause of such anomalous behavior. This maybe the case in some instances, but more importantly any system operating with a highly coherent field with a significant time dependent magnetic component at near 2° K will have the ability to organize the remaining free spins within the London penetration depth to form a coupled energy reservoir in the form of low mass spin waves. The niobium resonant cavities are composed of a single isotope with a large nuclear spin. When the other loss mechanisms are stripped away this may be the gain medium activated by the low level residual magnetic fields. It was found that one resonant cavity heat treatment produced optimum surface properties and then functioned as a MASER extracting energy from the 2° K thermal bath while cooling the cavity walls. The cavity operating in this mode is a simulator of what can take place in the wider but not colder universe using the cosmic microwave background (CMB) as a thermal source. The low mass, long lifetimes, and the scale of the magnetic spin waves on the weakly magnetized interstellar medium allows energy to be stored that is many orders of magnitude colder than the cosmic microwave background. A linear accelerator cavity becomes a tool to explore the properties of the long wave length magnetic spin waves that populate this cold low energy regime.

  10. Cold remedies (image)

    MedlinePlus

    Sore throat, cough, stuffy nose, sneezing, runny nose, fever, chills, and muscle aches are all symptoms associated with the common cold. Over-the-counter medicines for a cold only alleviate cold symptoms but do not shorten the duration of a cold. As always, ...

  11. Energy absorber for the CETA

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J.

    1994-01-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  12. Improvement Of The Helmholtz Absorber

    NASA Technical Reports Server (NTRS)

    Morrow, Duane L.

    1992-01-01

    Helmholtz-resonator system improved to enable it to absorb sound at more than one frequency without appreciable loss of effectiveness at primary frequency. Addition of annular cavities enables absorption of sound at harmonic frequencies in addition to primary frequency. Improved absorber designed for use on structures of high transmission loss. Applied to such machines as fixed-speed engines and fans.

  13. Metal-shearing energy absorber

    NASA Technical Reports Server (NTRS)

    Fay, R. J.; Wittrock, E. P.

    1971-01-01

    Device, consisting of tongue of thin aluminum alloy strip, pull tab, slotted steel plate which serves as cutter, and steel buckle, absorbs mechanical energy when its ends are subjected to tensile loading. Device is applicable as auxiliary shock absorbing anchor for automobile and airplane safety belts.

  14. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  15. AN X-RAY SPECTRAL MODEL OF REPROCESSING BY SMOOTH AND CLUMPY MOLECULAR TORI IN ACTIVE GALACTIC NUCLEI WITH THE MONACO FRAMEWORK

    SciTech Connect

    Furui, Shun’ya; Fukazawa, Yasushi; Ohno, Masanori; Hayashi, Kazuma; Odaka, Hirokazu; Kawaguchi, Toshihiro

    2016-02-20

    We construct an X-ray spectral model of reprocessing by a torus in an active galactic nucleus (AGN) with the Monte Carlo simulation framework MONACO. Two torus geometries of smooth and clumpy cases are considered and compared. In order to reproduce a Compton shoulder accurately, MONACO includes not only free electron scattering but also bound electron scattering. Raman and Rayleigh scattering are also treated, and scattering cross sections dependent on chemical states of hydrogen and helium are included. Doppler broadening by turbulence velocity can be implemented. Our model gives results consistent with other available models, such as MYTorus, except for differences due to different physical parameters and assumptions. We studied the dependence on torus parameters for a Compton shoulder, and found that a intensity ratio of a Compton shoulder to the line core mainly depends on column density, inclination angle, and metal abundance. For instance, an increase of metal abundance makes a Compton shoulder relatively weak. Also, the shape of a Compton shoulder depends on the column density. Furthermore, these dependences become different between smooth and clumpy cases. Then, we discuss the possibility of ASTRO-H/SXS spectroscopy of Compton shoulders in AGN reflection spectra.

  16. Acceleration of thin flyer foils with a 1 MA pulsed power device for shock-wave experiments in clumpy foam targets

    NASA Astrophysics Data System (ADS)

    Neff, Stephan; Ford, Jessica; Martinez, David; Plechaty, Christopher; Wright, Sandra; Presura, Radu

    2007-11-01

    The dynamics of shock waves in clumpy media are important for understanding many astrophysical processes, including the triggering of star formation in interstellar gas clouds by passing shock waves. This phenomena can be studied in the laboratory by launching a flyer plate into a low density foam with clumps. Low density foams offer the advantage of relative low sound speeds (a few hundred meters per second) compared to normal solids, thus reducing the flyer speed required to create shock waves. In first experiments aluminum foils with thicknesses between 20 micrometer and 130 micrometer were accelerated to speeds up to 2.3 km/s. In addition, the impact of the flyers on plexiglas targets was studied. Additional measurements will focus on optimizing the flyer properties (thicker flyers, higher velocities) and on characterizing the flyer in more detail (temperature of the flyer and plasma ablation from the flyer). The results of these measurements will be used to design an experiment studying the dynamics of shock waves in clumpy foams, using the 100 TW laser system Leopard for back-lighting the foam target.

  17. Absorbent product to absorb fluids. [for collection of human wastes

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multi-layer absorbent product for use in contact with the skin to absorb fluids is discussed. The product utilizes a water pervious facing layer for contacting the skin, overlayed by a first fibrous wicking layer, the wicking layer preferably being of the one-way variety in which fluid or liquid is moved away from the facing layer. The product further includes a first container section defined by inner and outer layer of a water pervious wicking material between which is disposed a first absorbent mass. A second container section defined by inner and outer layers between which is disposed a second absorbent mass and a liquid impermeable/gas permeable layer. Spacesuit applications are discussed.

  18. An introduction to absorbent dressings.

    PubMed

    Jones, Menna Lloyd

    2014-12-01

    Exudate bathes the wound bed with a serous fluid that contains essential components that promote wound healing. However, excess exudate is often seen as a challenge for clinicians. Absorbent dressings are often used to aid in the management of exudate, with the aim of providing a moist but unmacerated environment. With so many different types of absorbent dressings available today-alongside making a holistic assessment-it is essential that clinicians also have the knowledge and skill to select the most appropriate absorbent dressing for a given patient.

  19. Self-Regulating Shock Absorber

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J.

    1995-01-01

    Mechanical shock absorber keeps frictional damping force within tolerable limit. Its damping force does not increase with coefficient of friction between energy-absorbing components; rather, frictional damping force varies only slightly. Relatively insensitive to manufacturing variations and environmental conditions altering friction. Does not exhibit high breakaway friction and consequent sharp increase followed by sharp decrease in damping force at beginning of stroking. Damping force in absorber does not vary appreciably with speed of stroking. In addition, not vulnerable to leakage of hydraulic fluid.

  20. Anatomy of the AGN in NGC 5548: Evidence for an unexpected, new, heavy, variable and complex absorber

    NASA Astrophysics Data System (ADS)

    Cappi, M.; De Marco, B.; Ponti, G.; NGC 5548 Collaboration

    2014-07-01

    After a very successful multi-satellite campaign on Mrk 509 in 2009, we conducted a similar campaign on the AGN NGC 5548 in 2013. The source appeared strongly absorbed in the soft X-rays during this campaign, and signatures of strong outflows were also present in the UV. A talk (PI: J. Kaastra) of an overview of this campaign is also proposed to this conference. I propose here to present the EPIC results from the campaign focusing on the analysis of the new, heavy, and variable absorber found in this otherwise archetypical type-1 source. I will put these results into context by reviewing other recent evidence for massive (either highly ionized or neutral) absorbers along the line of sight of other type-1 AGNs, and will present some of their possible interpretations under discussion in the literature: from eclipsing broad line region clouds, to clumpy dusty tori and accretion disc winds. Finally, I will argue that the combination of our new X-ray and UV data for NGC5548 places interesting and severe constraints on some of these interpretations.

  1. Cold Stress and the Cold Pressor Test

    ERIC Educational Resources Information Center

    Silverthorn, Dee U.; Michael, Joel

    2013-01-01

    Temperature and other environmental stressors are known to affect blood pressure and heart rate. In this activity, students perform the cold pressor test, demonstrating increased blood pressure during a 1- to 2-min immersion of one hand in ice water. The cold pressor test is used clinically to evaluate autonomic and left ventricular function. This…

  2. Spontaneous emission and absorber theory

    NASA Astrophysics Data System (ADS)

    Pegg, David T.

    1997-01-01

    One of the long term interests of George Series was the construction of a theory of spontaneous emission which does not involve field quantisation. His approach was written in terms of atomic operators only and he drew a parallel with the Wheeler-Feynman absorber theory of radiation. By making a particular extra postulate, he was able to obtain the correct spontaneous emission rate and the Lamb shift reasonably simply and directly. An examination of his approach indicates that this postulate is physically reasonable and the need for it arises because quantisation in his theory occurs after the response of the absorber has been accounted for by means of the radiative reaction field. We review briefly an alternative absorber theory approach to spontaneous emission based on the direct action between the emitting atom and a quantised absorber, and outline some applications to more recent effects of interest in quantum optics.

  3. Guided tissue regeneration. Absorbable barriers.

    PubMed

    Wang, H L; MacNeil, R L

    1998-07-01

    Over the past 15 years, techniques aimed at regeneration of lost periodontal tissue have become widely used and accepted in clinical practice. Among these techniques are those which use the principles of guided tissue regeneration (GTR), wherein barriers (i.e., membranes) are used to control cell and tissue repopulation of the periodontal wound. A variety of non-absorbable and absorbable barriers have been developed and used for this purpose, with a trend in recent years toward increased use of absorbable GTR materials. This article describes the evolution of absorbable barrier materials and overview materials available for clinical use today. In addition, advantages and disadvantages of these materials are discussed, as well as possible new developments in barrier-based GTR therapy.

  4. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, W.H.

    1984-10-16

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system. 9 figs.

  5. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, William H.

    1984-01-01

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system.

  6. Perfect selective metamaterial solar absorbers.

    PubMed

    Wang, Hao; Wang, Liping

    2013-11-04

    In this work, we numerically investigate the radiative properties of metamaterial nanostructures made of two-dimensional tungsten gratings on a thin dielectric spacer and an opaque tungsten film from UV to mid-infrared region as potential selective solar absorbers. The metamaterial absorber with single-sized tungsten patches exhibits high absorptance in the visible and near-infrared region due to several mechanisms such as surface plasmon polaritons, magnetic polaritons, and intrinsic bandgap absorption of tungsten. Geometric effects on the resonance wavelengths and the absorptance spectra are studied, and the physical mechanisms are elucidated in detail. The absorptance could be further enhanced in a broader spectral range with double-sized metamaterial absorbers. The total solar absorptance of the optimized metamaterial absorbers at normal incidence could be more than 88%, while the total emittance is less than 3% at 100°C, resulting in total photon-to-heat conversion efficiency of 86% without any optical concentration. Moreover, the metamaterial solar absorbers exhibit quasi-diffuse behaviors as well as polarization independence. The results here will facilitate the design of novel highly efficient solar absorbers to enhance the performance of various solar energy conversion systems.

  7. Cold and Cough Medicines

    MedlinePlus

    ... What can you do for your cold or cough symptoms? Besides drinking lots of fluids and getting ... medicines. There are lots of different cold and cough medicines, and they do different things. Nasal decongestants - ...

  8. Cold medicines and children

    MedlinePlus

    ... aspx . Accessed July 26, 2016. Cherry JD. The common cold. In: Cherry JD, Harrison GJ, Kaplan SL, Steinbach ... 2014:chap 7. Miller EK, Williams JV. The common cold. In: Kliegman RM, Stanton BF, St. Geme JW, ...

  9. Skin Reactions to Cold

    PubMed Central

    Talpash, Orest

    1976-01-01

    Although skin reactions to cold are seen surprisingly infrequently in Canada, it is important to manage them correctly when they do occur. Frostbite, cold urticarias, Raynaud's disease and phenomenon, and several miscellaneous changes are discussed. PMID:21308019

  10. Cold knife cone biopsy

    MedlinePlus

    ... biopsy; Pap smear - cone biopsy; HPV - cone biopsy; Human papilloma virus - cone biopsy; Cervix - cone biopsy; Colposcopy - cone biopsy Images Female reproductive anatomy Cold cone biopsy Cold cone removal References American ...

  11. Mushroom plasmonic metamaterial infrared absorbers

    SciTech Connect

    Ogawa, Shinpei Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-26

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF{sub 2} etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  12. Mushroom plasmonic metamaterial infrared absorbers

    NASA Astrophysics Data System (ADS)

    Ogawa, Shinpei; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-01

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  13. Additive manufacturing of RF absorbers

    NASA Astrophysics Data System (ADS)

    Mills, Matthew S.

    The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

  14. Carbon Absorber Retrofit Equipment (CARE)

    SciTech Connect

    Klein, Eric

    2015-12-23

    During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO2) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO2 removal was achieved with greater than 95% CO2product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO2 captured from a sub-critical PC plant.

  15. Low temperature selective absorber research

    NASA Astrophysics Data System (ADS)

    Herzenberg, S. A.; Silberglitt, R.

    1982-04-01

    Research carried out since 1979 on selective absorbers is surveyed, with particular attention given to the low-temperature coatings seen as promising for flat plate and evacuated tube applications. The most thoroughly investigated absorber is black chrome, which is highly selective and is the most durable low-temperature absorber. It is believed that other materials, because of their low cost and lower content of strategic materials, may eventually supplant black chrome. Among these candidates are chemically converted black nickel; anodically oxidized nickel, zinc, and copper composites; and nickel or other low-cost multilayer coatings. In reviewing medium and high-temperature research, black chrome, multilayer coatings and black cobalt are seen as best medium-temperature candidates. For high temperatures, an Al2O3/Pt-Al203 multilayer composite or the zirconium diboride coating is preferred.

  16. How cold is cold dark matter?

    SciTech Connect

    Armendariz-Picon, Cristian; Neelakanta, Jayanth T. E-mail: jtneelak@syr.edu

    2014-03-01

    If cold dark matter consists of particles, these must be non-interacting and non-relativistic by definition. In most cold dark matter models however, dark matter particles inherit a non-vanishing velocity dispersion from interactions in the early universe, a velocity that redshifts with cosmic expansion but certainly remains non-zero. In this article, we place model-independent constraints on the dark matter temperature to mass ratio, whose square root determines the dark matter velocity dispersion. We only assume that dark matter particles decoupled kinetically while non-relativistic, when galactic scales had not entered the horizon yet, and that their momentum distribution has been Maxwellian since that time. Under these assumptions, using cosmic microwave background and matter power spectrum observations, we place upper limits on the temperature to mass ratio of cold dark matter today (away from collapsed structures). These limits imply that the present cold dark matter velocity dispersion has to be smaller than 54 m/s. Cold dark matter has to be quite cold, indeed.

  17. Magnetically tunable metamaterial perfect absorber

    NASA Astrophysics Data System (ADS)

    Lei, Ming; Feng, Ningyue; Wang, Qingmin; Hao, Yanan; Huang, Shanguo; Bi, Ke

    2016-06-01

    A magnetically tunable metamaterial perfect absorber (MPA) based on ferromagnetic resonance is experimentally and numerically demonstrated. The ferrite-based MPA is composed of an array of ferrite rods and a metallic ground plane. Frequency dependent absorption of the ferrite-based MPA under a series of applied magnetic fields is discussed. An absorption peak induced by ferromagnetic resonance appears in the range of 8-12 GHz under a certain magnetic field. Both the simulated and experimental results demonstrate that the absorption frequency of the ferrite-based MPA can be tuned by the applied magnetic field. This work provides an effective way to fabricate the magnetically tunable metamaterial perfect absorber.

  18. Adaptive inertial shock-absorber

    NASA Astrophysics Data System (ADS)

    Faraj, Rami; Holnicki-Szulc, Jan; Knap, Lech; Seńko, Jarosław

    2016-03-01

    This paper introduces and discusses a new concept of impact absorption by means of impact energy management and storage in dedicated rotating inertial discs. The effectiveness of the concept is demonstrated in a selected case-study involving spinning management, a recently developed novel impact-absorber. A specific control technique performed on this device is demonstrated to be the main source of significant improvement in the overall efficiency of impact damping process. The influence of various parameters on the performance of the shock-absorber is investigated. Design and manufacturing challenges and directions of further research are formulated.

  19. Damage tolerant light absorbing material

    DOEpatents

    Lauf, R.J.; Hamby, C. Jr.; Akerman, M.A.; Seals, R.D.

    1993-09-07

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, is prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000 C to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm[sup 3]. 9 figures.

  20. Damage tolerant light absorbing material

    DOEpatents

    Lauf, Robert J.; Hamby, Jr., Clyde; Akerman, M. Alfred; Seals, Roland D.

    1993-01-01

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000.degree. C. to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm.sup.3.

  1. Counterflow absorber for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

    An air-cooled, vertical tube absorber for an absorption refrigeration system is disclosed. Strong absorbent solution is supplied to the top of the absorber and refrigerant vapor is supplied to the bottom of the absorber to create a direct counterflow of refrigerant vapor and absorbent solution in the absorber. The refrigeration system is designed so that the volume flow rate of refrigerant vapor in the tubes of the absorber is sufficient to create a substantially direct counterflow along the entire length of each tube in the absorber. This provides several advantages for the absorber such as higher efficiency and improved heat transfer characteristics, and allows improved purging of non-condensibles from the absorber.

  2. Metamaterial Absorbers for Microwave Detection

    DTIC Science & Technology

    2015-06-01

    a) Depiction of metamaterial array of square resonators atop FR4. (b) Metamaterial dimensions and structure...comparison for varying resonator array dimension sizes. ..............23 Figure 12. Absorption derived from raw reflection data...36 x Figure 23. Metamaterial absorber array where resonator dimensions control the detection frequencies and

  3. Oil and fat absorbing polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A method is described for forming a solid network polymer having a minimal amount of crosslinking for use in absorbing fats and oils. The polymer remains solid at a swelling ratio in oil or fat of at least ten and provides an oil absorption greater than 900 weight percent.

  4. [Cold-induced urticaria].

    PubMed

    Delorme, N; Drouet, M; Thibaudeau, A; Verret, J L

    2002-09-01

    Cold urticaria is characterized by the development of urticaria, usually superficial and/or angioedematous reaction after cold contact. It was found predominantly in young women. The diagnosis is based on the history and ice cube test. Patients with a negative ice cube test may have represented systemic cold urticaria (atypical acquired cold urticaria) induced by general body cooling. The pathogenesis is poorly understood. Cold urticaria can be classified into acquired and familial disorders, with an autosomal dominant inheritance. Idiopathic cold urticaria is most common type but the research of a cryopathy is necessary. Therapy is often difficult. It is essential that the patient be warned of the dangers of swimming in cold water because systemic hypotension can occur. H1 antihistamines can be used for treatment of cold urticaria but the clinical responses are highly variable. The combination with an H2 antagonists is more effective. Doxepin may be useful in the treatment. Leukotriene receptor antagonists may be a novel, promising drug entity. In patients who do not respond to previous treatments, induction of cold tolerance may be tried.

  5. Cold fusion, Alchemist's dream

    SciTech Connect

    Clayton, E.D.

    1989-09-01

    In this report the following topics relating to cold fusion are discussed: muon catalysed cold fusion; piezonuclear fusion; sundry explanations pertaining to cold fusion; cosmic ray muon catalysed cold fusion; vibrational mechanisms in excited states of D{sub 2} molecules; barrier penetration probabilities within the hydrogenated metal lattice/piezonuclear fusion; branching ratios of D{sub 2} fusion at low energies; fusion of deuterons into {sup 4}He; secondary D+T fusion within the hydrogenated metal lattice; {sup 3}He to {sup 4}He ratio within the metal lattice; shock induced fusion; and anomalously high isotopic ratios of {sup 3}He/{sup 4}He.

  6. OVI absorbers in SDSS spectra

    NASA Astrophysics Data System (ADS)

    Frank, Stephan

    We conducted a systematic search for signatures of the Intergalactic Medium (IGM) in Quasar spectra of the Sloan Digital Sky Survey (SDSS) Data Release 3 (DR3), focusing on finding intervening absorbers via detection of their O VI doublet. We present a search algorithm, and criteria for distinguishing candidates from spurious Lyman a forest lines. In addition, we compare our findings with simulations of the Lyman a forest in order to estimate the detectability of O VI doublets over various redshift intervals. We obtain a sample of 1866 O VI doublet candidates with rest-frame equivalent width >= 0.05 λ in 855 AGN spectra (out of 3702 objects with redshifts in the range accessible for O VI detection). This sample is subdivided into 3 groups according to the likelihood of being real and the potential for follow-up observation of the candidate. The group with the cleanest and most secure candidates is comprised of 145 candidates. 69 of these reside at a velocity separation >= 5000 km/s from the QSO, and can therefore be classified tentatively as intervening absorbers. Most of these absorbers have not been picked up by earlier, automated QSO absorption line detection algorithms. This sample increases the number of known O VI absorbers at redshifts beyond z abs >= 2.7 substantially. We propose to obtain observations of some of the candidates with the best signatures for O VI doublets with high signal-to-noise and high resolution in order to better constrain the physical state of the absorbers. We then focused on a subsample of 387 AGN sightlines with an average S/N >= 5: 0, allowing for the detection of absorbers above a rest-frame equivalent width limit of W r >= 0:19 ? A for the O VI 1032 λ component. Accounting for random interlopers mimicking an O VI doublet, we derive for the first time a secure lower limit for the redshift number density DN/Dz for redshifts z abs >= 2:8. With extensive Monte Carlo simulations we quantify the losses of absorbers due to blending

  7. Cold stress and the cold pressor test.

    PubMed

    Silverthorn, Dee U; Michael, Joel

    2013-03-01

    Temperature and other environmental stressors are known to affect blood pressure and heart rate. In this activity, students perform the cold pressor test, demonstrating increased blood pressure during a 1- to 2-min immersion of one hand in ice water. The cold pressor test is used clinically to evaluate autonomic and left ventricular function. This activity is easily adapted to an inquiry format that asks students to go to the scientific literature to learn about the test and then design a protocol for carrying out the test in classmates. The data collected are ideal for teaching graphical presentation of data and statistical analysis.

  8. Light-absorbing impurities in Arctic snow

    NASA Astrophysics Data System (ADS)

    Doherty, S. J.; Warren, S. G.; Grenfell, T. C.; Clarke, A. D.; Brandt, R. E.

    2010-12-01

    Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983-1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean during 1998 and 2005-2009, on tundra, glaciers, ice caps, sea ice, frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack is accessible for sampling. Sampling was carried out in summer on the Greenland Ice Sheet and on the Arctic Ocean, of melting glacier snow and sea ice as well as cold snow. About 1200 snow samples have been analyzed for this study. The snow is melted and filtered; the filters are analyzed in a specially designed spectrophotometer system to infer the concentration of black carbon (BC), the fraction of absorption due to non-BC light-absorbing constituents and the absorption Ångstrom exponent of all particles. This is done using BC calibration standards having a mass absorption efficiency of 6.0 m2 g-1 at 550 nm and by making an assumption that the absorption Angstrom exponent for BC is 1.0 and for non-BC light-absorbing aerosol is 5.0. The reduction of snow albedo is primarily due to BC, but other impurities, principally brown (organic) carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. The meltwater from selected snow samples was saved for chemical analysis to identify sources of the impurities. Median BC amounts in surface snow are as follows (nanograms of carbon per gram of snow): Greenland 3, Arctic Ocean snow 7, melting sea ice 8, Arctic Canada 8, subarctic Canada 14

  9. Digital Alloy Absorber for Photodetectors

    NASA Technical Reports Server (NTRS)

    Hill, Cory J. (Inventor); Ting, David Z. (Inventor); Gunapala, Sarath D. (Inventor)

    2016-01-01

    In order to increase the spectral response range and improve the mobility of the photo-generated carriers (e.g. in an nBn photodetector), a digital alloy absorber may be employed by embedding one (or fraction thereof) to several monolayers of a semiconductor material (insert layers) periodically into a different host semiconductor material of the absorber layer. The semiconductor material of the insert layer and the host semiconductor materials may have lattice constants that are substantially mismatched. For example, this may performed by periodically embedding monolayers of InSb into an InAsSb host as the absorption region to extend the cutoff wavelength of InAsSb photodetectors, such as InAsSb based nBn devices. The described technique allows for simultaneous control of alloy composition and net strain, which are both key parameters for the photodetector operation.

  10. Exercise in the Cold

    PubMed Central

    Fudge, Jessie

    2016-01-01

    Context: Hypothermia and frostbite injuries occur in cold weather activities and sporting events. Evidence Acquisition: A PubMed search was used to identify original research and review articles related to cold, frostbite, and hypothermia. Inclusion was based on their relevance to prevention and treatment of cold-related injuries in sports and outdoor activities. Dates of review articles were limited to those published after 2010. No date limit was set for the most recent consensus statements or original research. Study Design: Clinical review. Level of Evidence: Level 5. Results: Frostbite and hypothermia are well-documented entities with good prevention strategies and prehospital treatment recommendations that have changed very little with time. A layered approach to clothing is the best way to prevent injury and respond to weather changes. Each athlete, defined as a participant in a cold weather sport or activity, will respond to cold differently depending on anthropometric measurements and underlying medical risk factors. An understanding of wind-chill temperatures, wetness, and the weather forecast allows athletes and event coordinators to properly respond to changing weather conditions. At the first sign of a freezing cold injury, ensure warm, dry clothes and move to a protected environment. Conclusion: Cold injuries can be prevented, and cold weather activities are safe with proper education, preparation, and response to changing weather conditions or injury. PMID:26857732

  11. Cold fusion research

    SciTech Connect

    1989-11-01

    I am pleased to forward to you the Final Report of the Cold Fusion Panel. This report reviews the current status of cold fusion and includes major chapters on Calorimetry and Excess Heat, Fusion Products and Materials Characterization. In addition, the report makes a number of conclusions and recommendations, as requested by the Secretary of Energy.

  12. Cold-Weather Sports

    MedlinePlus

    ... Surgery? A Week of Healthy Breakfasts Shyness Cold-Weather Sports KidsHealth > For Teens > Cold-Weather Sports Print A A A What's in this ... Equipment Ahh, winter! Shorter days. Frigid temperatures. Foul weather. What better time to be outdoors? Winter sports ...

  13. Cold Sores (HSV-1)

    MedlinePlus

    ... A Week of Healthy Breakfasts Shyness Cold Sores (HSV-1) KidsHealth > For Teens > Cold Sores (HSV-1) A A A What's in this article? ... or around a person's lips, are caused by herpes simplex virus-1 (HSV-1) . But they don't ...

  14. Chilling Out With Colds

    MedlinePlus

    ... Your head hurts. You don't have the energy to even get out of bed. And you can't breathe out of your nose. What's wrong? You may have a cold! Having a cold is the #1 reason kids visit the doctor and stay home from school. Kids can get six to ten ...

  15. Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody

    PubMed Central

    Zhu, Linxiao; Raman, Aaswath P.; Fan, Shanhui

    2015-01-01

    A solar absorber, under the sun, is heated up by sunlight. In many applications, including solar cells and outdoor structures, the absorption of sunlight is intrinsic for either operational or aesthetic considerations, but the resulting heating is undesirable. Because a solar absorber by necessity faces the sky, it also naturally has radiative access to the coldness of the universe. Therefore, in these applications it would be very attractive to directly use the sky as a heat sink while preserving solar absorption properties. Here we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal. When placed on a silicon absorber under sunlight, such a blackbody preserves or even slightly enhances sunlight absorption, but reduces the temperature of the underlying silicon absorber by as much as 13 °C due to radiative cooling. Our work shows that the concept of radiative cooling can be used in combination with the utilization of sunlight, enabling new technological capabilities. PMID:26392542

  16. Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody.

    PubMed

    Zhu, Linxiao; Raman, Aaswath P; Fan, Shanhui

    2015-10-06

    A solar absorber, under the sun, is heated up by sunlight. In many applications, including solar cells and outdoor structures, the absorption of sunlight is intrinsic for either operational or aesthetic considerations, but the resulting heating is undesirable. Because a solar absorber by necessity faces the sky, it also naturally has radiative access to the coldness of the universe. Therefore, in these applications it would be very attractive to directly use the sky as a heat sink while preserving solar absorption properties. Here we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal. When placed on a silicon absorber under sunlight, such a blackbody preserves or even slightly enhances sunlight absorption, but reduces the temperature of the underlying silicon absorber by as much as 13 °C due to radiative cooling. Our work shows that the concept of radiative cooling can be used in combination with the utilization of sunlight, enabling new technological capabilities.

  17. A tale of three galaxies: A "CLUMPY" view of the spectroscopically anomalous galaxies IRAS F10398+1455, IRAS F21013-0739 and SDSS J0808+3948

    NASA Astrophysics Data System (ADS)

    Xie, Yanxia; Nikutta, Robert; Hao, Lei; Li, Aigen

    2016-11-01

    We investigate the dust properties in three spectroscopically anomalous galaxies (IRAS F10398+1455, IRAS F21013-0739 and SDSS J0808+3948). Their Spitzer/IRS spectra are characterized by a steep ∼5-8 μm emission continuum, strong emission bands from polycyclic aromatic hydrocarbon (PAH) molecules, and prominent 10 μm silicate emission. The steep ∼5-8 μm continuum and strong PAH emission features suggest the presence of starbursts, while the silicate emission is indicative of significant heating from AGNs. The simultaneous detection of these two observational properties has rarely been reported on galactic scale. We employ the PAHFIT software to estimate their starlight contributions, and the CLUMPY model for the components contributed by the AGN tori. We find that the CLUMPY model is generally successful in explaining the overall dust infrared emission, although it appears to emit too flat at the ∼5-8 μm continuum to be consistent with that observed in IRAS F10398+1455 and IRAS F21013-0739. The flat ∼5-8 μm continuum calculated from the CLUMPY model could arise from the adopted specific silicate opacity of Ossenkopf et al. (1992) which exceeds that of the Draine and Lee (1984) "astronomical silicate" by a factor up to 2 in the ∼5-8 μm wavelength range. Future models with a variety of dust species incorporated in the CLUMPY radiation transfer regime are needed for a thorough understanding of the dust properties of these spectroscopically anomalous galaxies.

  18. Shock absorber operates over wide range

    NASA Technical Reports Server (NTRS)

    Creasy, W. K.; Jones, J. C.

    1965-01-01

    Piston-type hydraulic shock absorber, with a metered damping system, operates over a wide range of kinetic energy loading rates. It is used for absorbing shock and vibration on mounted machinery and heavy earth-moving equipment.

  19. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... absorber is a device made of paper or cotton intended to absorb moisture from the oral cavity during dental... manufacturing practice requirements of the quality system regulation in part 820 of this chapter, with...

  20. Resolving the Clumpy Structure of the Outflow Winds in the Gravitationally Lensed Quasar SDSS J1029+2623

    NASA Astrophysics Data System (ADS)

    Misawa, Toru; Inada, Naohisa; Oguri, Masamune; Gandhi, Poshak; Horiuchi, Takashi; Koyamada, Suzuka; Okamoto, Rina

    2014-10-01

    We study the geometry and the internal structure of the outflowing wind from the accretion disk of a quasar by observing multiple sightlines with the aid of strong gravitational lensing. Using Subaru/High Dispersion Spectrograph, we performed high-resolution (R ~ 36,000) spectroscopic observations of images A and B of the gravitationally lensed quasar SDSS J1029+2623 (at z em ~ 2.197) whose image separation angle, θ ~ 22.''5, is the largest among those discovered so far. We confirm that the difference in absorption profiles in images A and B discovered by Misawa et al. has remained unchanged since 2010, implying the difference is not due to time variability of the absorption profiles over the delay between the images, Δt ~ 744 days, but rather due to differences along the sightlines. We also discovered a time variation of C IV absorption strength in both images A and B due to a change in the ionization condition. If a typical absorber's size is smaller than its distance from the flux source by more than five orders of magnitude, it should be possible to detect sightline variations among images of other smaller separation, galaxy-scale gravitationally lensed quasars. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  1. RESOLVING THE CLUMPY STRUCTURE OF THE OUTFLOW WINDS IN THE GRAVITATIONALLY LENSED QUASAR SDSS J1029+2623

    SciTech Connect

    Misawa, Toru; Inada, Naohisa; Oguri, Masamune; Gandhi, Poshak; Horiuchi, Takashi; Koyamada, Suzuka; Okamoto, Rina

    2014-10-20

    We study the geometry and the internal structure of the outflowing wind from the accretion disk of a quasar by observing multiple sightlines with the aid of strong gravitational lensing. Using Subaru/High Dispersion Spectrograph, we performed high-resolution (R ∼ 36,000) spectroscopic observations of images A and B of the gravitationally lensed quasar SDSS J1029+2623 (at z {sub em} ∼ 2.197) whose image separation angle, θ ∼ 22.''5, is the largest among those discovered so far. We confirm that the difference in absorption profiles in images A and B discovered by Misawa et al. has remained unchanged since 2010, implying the difference is not due to time variability of the absorption profiles over the delay between the images, Δt ∼ 744 days, but rather due to differences along the sightlines. We also discovered a time variation of C IV absorption strength in both images A and B due to a change in the ionization condition. If a typical absorber's size is smaller than its distance from the flux source by more than five orders of magnitude, it should be possible to detect sightline variations among images of other smaller separation, galaxy-scale gravitationally lensed quasars.

  2. Improving the laboratory monitoring of absorbent oil

    SciTech Connect

    V.S. Shved; S.S. Sychev; I.V. Safina; S.A. Klykov

    2009-05-15

    The performance of absorbent coal tar oil is analyzed as a function of the constituent and group composition. The qualitative and quantitative composition of the oil that ensures the required absorbent properties is determined. Operative monitoring may be based on absorbent characteristics that permit regulation of the beginning and end of regeneration.

  3. Cold subcutaneous abscesses.

    PubMed Central

    Jackson, R.; Stephens, L.; Kelly, A. P.

    1990-01-01

    Cold abscesses are defined as having no associated erythema, heat, or tenderness. They may be present in immunodeficiency disorders, deep mycoses, and other infectious diseases. As there is a dearth information on this subject in the dermatology, surgery, and infectious disease literature, we present a case of cold abscesses secondary to coccidioidomycosis and discuss the possible role of humoral immunity, cell-mediated immunity, prostaglandins, T cells, and other mediators in cold abscess pathogenesis. In addition, therapeutic guidelines for abscesses are reviewed. Images Figure 1 Figure 2 PMID:2280425

  4. Miniature cold gas thrusters

    NASA Astrophysics Data System (ADS)

    Bzibziak, R. J., Sr.

    1992-07-01

    Cold gas thrusters provide a safe, inexpensive, lightweight and reliable means of propulsive control for small satellites, projectiles and maneuvering control systems. Moog Inc. has designed and developed a family of miniature cold gas thrusters for use on Strategic Defense Iniative flight simulation experiments, sounding rockets, small satellite applications, astronaut control systems, and close proximity maneuvering systems for Space System. Construction features such as coil assembly, core assembly, armature assembly, external housing and valve body are discussed. The design approach, performance characteristics and functional description of cold gas thrusters designed for various applications are presented.

  5. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, Daniel C.

    1990-02-06

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  6. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, D.C.

    1987-11-20

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compound of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved. 2 figs.

  7. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, Daniel C.

    1990-01-01

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  8. Carbon dioxide absorbents for rebreather diving.

    PubMed

    Pennefather, John

    2016-09-01

    Firstly I would like to thank SPUMS members for making me a Life Member of SPUMS; I was surprised and greatly honoured by the award. I also want to confirm and expand on the findings on carbon dioxide absorbents reported by David Harvey et al. For about 35 years, I was the main player in deciding which absorbent went into Australian Navy and Army diving sets. On several occasions, suppliers of absorbents to the anaesthesia market tried to supply the Australian military market. On no occasion did they provide absorbent that came close to the minimum absorbent capacity required, generally being 30-40% less efficient than diving-grade absorbents. Because I regard lives as being more important than any likely dollar saving, the best absorbent was always selected unless two suppliers provided samples with the same absorbent capacity. On almost every occasion, there was a clear winner and cost was never considered. I suggest the same argument for the best absorbent should be used by members and their friends who dive using rebreather sets. I make this point because of my findings on a set that was brought to me after the death of its owner. The absorbent was not the type or grain size recommended by the manufacturer of the set and did not resemble any of the diving grade absorbents I knew of. I suspected by its appearance that it was anaesthetic grade absorbent. When I tested the set, the absorbent system failed very quickly so it is likely that carbon dioxide toxicity contributed to his death. The death was not the subject of an inquest and I have no knowledge of how the man obtained the absorbent. Possibly there was someone from an operating theatre staff who unintentionally caused their friend's death by supplying him with 'borrowed absorbent'. I make this point as I would like to discourage members from making a similar error.

  9. Light-absorbing impurities in Arctic snow

    NASA Astrophysics Data System (ADS)

    Doherty, S. J.; Warren, S. G.; Grenfell, T. C.; Clarke, A. D.; Brandt, R. E.

    2010-08-01

    Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983-1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean during 2005-2009, on tundra, glaciers, ice caps, sea ice, frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack is accessible for sampling. Sampling was carried out in summer on the Greenland ice sheet and on the Arctic Ocean, of melting glacier snow and sea ice as well as cold snow. About 1200 snow samples have been analyzed for this study. The snow is melted and filtered; the filters are analyzed in a specially designed spectrophotometer system to infer the concentration of black carbon (BC), the fraction of absorption due to non-BC light-absorbing constituents and the absorption Ångstrom exponent of all particles. The reduction of snow albedo is primarily due to BC, but other impurities, principally brown (organic) carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. The meltwater from selected snow samples was saved for chemical analysis to identify sources of the impurities. Median BC amounts in surface snow are as follows (nanograms of carbon per gram of snow): Greenland 3, Arctic Ocean snow 7, melting sea ice 8, Arctic Canada 8, Subarctic Canada 14, Svalbard 13, Northern Norway 21, Western Arctic Russia 26, Northeastern Siberia 17. Concentrations are more variable in the European Arctic than in Arctic Canada or the Arctic Ocean, probably because of the proximity to BC sources. Individual

  10. Cold hardiness in molluscs

    NASA Astrophysics Data System (ADS)

    Ansart, Armelle; Vernon, Philippe

    2003-05-01

    Molluscs inhabit all types of environments: seawater, intertidal zone, freshwater and land, and of course may have to deal with subzero temperatures. Ectotherm animals survive cold conditions by avoiding it by extensive supercooling (freezing avoidant species) or by bearing the freezing of their extracellular body fluids (freezing tolerant species). Although some studies on cold hardiness are available for intertidal molluscs, they are scarce for freshwater and terrestrial ones. Molluscs often exhibit intermediary levels of cold hardiness, with a moderate or low ability to supercool and a limited survival to the freezing of their tissues. Several factors could be involved: their dependence on water, their ability to enter dormancy, the probability of inoculative freezing in their environment, etc. Size is an important parameter in the development of cold hardiness abilities: it influences supercooling ability in land snails, which are rather freezing avoidant and survival to ice formation in intertidal organisms, which generally tolerate freezing.

  11. Colds and flus - antibiotics

    MedlinePlus

    Fashner J, Ericson K, Werner S. Treatment of the common cold in children and adults. Am Fam Physician. 2012; ... gov/pubmed/22962927 . Melio FR, Berge LR. Upper respiratory tract infections. In: Marx JA, Hockberger RS, Walls RM, et ...

  12. Coping with Colds

    MedlinePlus

    ... re hungry. And you might have heard that chicken soup can cure a cold. There's no real ... you have strep throat and need treatment with antibiotics. If your doctor does prescribe antibiotics, be sure ...

  13. The cold reading technique.

    PubMed

    Dutton, D L

    1988-04-15

    For many people, belief in the paranormal derives from personal experience of face-to-face interviews with astrologers, palm readers, aura and Tarot readers, and spirit mediums. These encounters typically involve cold reading, a process in which a reader makes calculated guesses about a client's background and problems and, depending on the reaction, elaborates a reading which seems to the client so uniquely appropriate that it carries with it the illusion of having been produced by paranormal means. The cold reading process is shown to depend initially on the Barnum effect, the tendency for people to embrace generalized personality descriptions as idiosyncratically their own. Psychological research into the Barnum effect is critically reviewed, and uses of the effect by a professional magician are described. This is followed by detailed analysis of the cold reading performances of a spirit medium. Future research should investigate the degree to which cold readers may have convinced themselves that they actually possess psychic or paranormal abilities.

  14. A polarization-independent broadband terahertz absorber

    SciTech Connect

    Shi, Cheng; Zang, XiaoFei E-mail: ymzhu@usst.edu.cn; Wang, YiQiao; Chen, Lin; Cai, Bin; Zhu, YiMing E-mail: ymzhu@usst.edu.cn

    2014-07-21

    A highly efficient broadband terahertz absorber is designed, fabricated, and experimentally as well as theoretically evaluated. The absorber comprises a heavily doped silicon substrate and a well-designed two-dimensional grating. Due to the destructive interference of waves and diffraction, the absorber can achieve over 95% absorption in a broad frequency range from 1 to 2 THz and for angles of incidence from 0° to 60°. Such a terahertz absorber is also polarization-independent due to its symmetrical structure. This omnidirectional and broadband absorber have potential applications in anti-reflection coatings, imaging systems, and so on.

  15. Teaching in a Cold Environment.

    ERIC Educational Resources Information Center

    Ewert, Alan

    1979-01-01

    Designed to help teachers deal with students in a cold environment, this article explains cold physiology and fundamental laws of heat; describes 14 common cold injuries and their current treatment; and lists a number of useful teaching techniques for cold environments. (SB)

  16. Teaching in a Cold Environment.

    ERIC Educational Resources Information Center

    Ewert, Alan

    Instructors who teach outdoors in an environment so cold as to cause injury must satisfy program objectives while avoiding cold injury to themselves and students, help students focus on learning instead of discomfort, and alleviate some students' intense fear of the cold. Dealing with the cold successfully requires a thorough knowledge of:…

  17. Understanding Colds: Anatomy of the Nose

    MedlinePlus

    ... Colds Prevention Treatment Children Complications Special Features References Common Cold Understanding Colds Anatomy of the Nose The nose ... cm (3/8 inch) per minute. What a Common Cold Is A common cold is an illness caused ...

  18. Reprint of : Thermoelectricity without absorbing energy from the heat sources

    NASA Astrophysics Data System (ADS)

    Whitney, Robert S.; Sánchez, Rafael; Haupt, Federica; Splettstoesser, Janine

    2016-08-01

    We analyze the power output of a quantum dot machine coupled to two electronic reservoirs via thermoelectric contacts, and to two thermal reservoirs - one hot and one cold. This machine is a nanoscale analogue of a conventional thermocouple heat-engine, in which the active region being heated is unavoidably also exchanging heat with its cold environment. Heat exchange between the dot and the thermal reservoirs is treated as a capacitive coupling to electronic fluctuations in localized levels, modeled as two additional quantum dots. The resulting multiple-dot setup is described using a master equation approach. We observe an "exotic" power generation, which remains finite even when the heat absorbed from the thermal reservoirs is zero (in other words the heat coming from the hot reservoir all escapes into the cold environment). This effect can be understood in terms of a non-local effect in which the heat flow from heat source to the cold environment generates power via a mechanism which we refer to as Coulomb heat drag. It relies on the fact that there is no relaxation in the quantum dot system, so electrons within it have a non-thermal energy distribution. More poetically, one can say that we find a spatial separation of the first-law of thermodynamics (heat to work conversion) from the second-law of thermodynamics (generation of entropy). We present circumstances in which this non-thermal system can generate more power than any conventional macroscopic thermocouple (with local thermalization), even when the latter works with Carnot efficiency.

  19. Cold moderators at ORNL

    SciTech Connect

    Lucas, A. T.

    1997-09-01

    The Advanced Neutron Source (ANS) cold moderators were not an 'Oak Ridge first', but would have been the largest both physically and in terms of cold neutron flux. Two cold moderators were planned each 410 mm in diameter and containing about 30L of liquid deuterium. They were to be completely independent of each other. A modular system design was used to provide greater reliability and serviceability. When the ANS was terminated, up–grading of the resident High Flux Isotope Reactor (HFIR) was examined and an initial study was made into the feasibility of adding a cold source. Because the ANS design was modular, it was possible to use many identical design features. Sub-cooled liquid at 4 bar abs was initially chosen for the HFIR design concept, but this was subsequently changed to 15 bar abs to operate above the critical pressure. As in the ANS, the hydrogen will operate at a constant pressure throughout the temperature range and a completely closed loop with secondary containment was adopted. The heat load of 2 kW made the heat flux comparable with that of the ANS. Subsequent studies into the construction of cryogenic moderators for the proposed new Synchrotron Neutron source indicated that again many of the same design concepts could be used. By connecting the two cold sources together in series, the total heat load of 2 kW is very close to that of the HFIR allowing a very similar supercritical hydrogen system to be configured. The two hydrogen moderators of the SNS provide a comparable heat load to the HFIR moderator. It is subsequently planned to connect the two in series and operate from a single cold loop system, once again using supercritical hydrogen. The spallation source also provided an opportunity to re-examine a cold pellet solid methane moderator operating at 20K.

  20. Liquid crystal tunable metamaterial absorber.

    PubMed

    Shrekenhamer, David; Chen, Wen-Chen; Padilla, Willie J

    2013-04-26

    We present an experimental demonstration of electronically tunable metamaterial absorbers in the terahertz regime. By incorporation of active liquid crystal into strategic locations within the metamaterial unit cell, we are able to modify the absorption by 30% at 2.62 THz, as well as tune the resonant absorption over 4% in bandwidth. Numerical full-wave simulations match well to experiments and clarify the underlying mechanism, i.e., a simultaneous tuning of both the electric and magnetic response that allows for the preservation of the resonant absorption. These results show that fundamental light interactions of surfaces can be dynamically controlled by all-electronic means and provide a path forward for realization of novel applications.

  1. Oxalate: Effect on calcium absorbability

    SciTech Connect

    Heaney, R.P.; Weaver, C.M. )

    1989-10-01

    Absorption of calcium from intrinsically labeled Ca oxalate was measured in 18 normal women and compared with absorption of Ca from milk in these same subjects, both when the test substances were ingested in separate meals and when ingested together. Fractional Ca absorption from oxalate averaged 0.100 +/- 0.043 when ingested alone and 0.140 +/- 0.063 when ingested together with milk. Absorption was, as expected, substantially lower than absorption from milk (0.358 +/- 0.113). Nevertheless Ca oxalate absorbability in these women was higher than we had previously found for spinach Ca. When milk and Ca oxalate were ingested together, there was no interference of oxalate in milk Ca absorption and no evidence of tracer exchange between the two labeled Ca species.

  2. A Lithium Bromide Absorption Chiller with Cold Storage

    DTIC Science & Technology

    2011-01-15

    TO R A G E A LITHIUM BROMIDE ABSORPTION CHILLER WITH COLD STORAGE William Gerstler, et al, General Electric Global Research UNCLASSIFIED UNLIMITED...Research ABSTRACT A LiBr-based absorption chiller can use waste heat or solar energy to produce useful space cooling for small buildings...However, operating this absorption chiller at high ambient tem- peratures may result in performance degradation, crystallization in the absorber, and

  3. Electromagnetic scattering by pyramidal and wedge absorber

    NASA Technical Reports Server (NTRS)

    Dewitt, Brian T.; Burnside, Walter D.

    1988-01-01

    Electromagnetic scattering from pyramidal and wedge absorbers used to line the walls of modern anechoic chambers is measured and compared with theoretically predicted values. The theoretical performance for various angles of incidence is studied. It is shown that a pyramidal absorber scatters electromagnetic energy more as a random rough surface does. The apparent reflection coefficient from an absorber wall illuminated by a plane wave can be much less than the normal absorber specifications quoted by the manufacturer. For angles near grazing incidence, pyramidal absorbers give a large backscattered field from the pyramid side-faces or edges. The wedge absorber was found to give small backscattered fields for near-grazing incidence. Based on this study, some new guidelines for the design of anechoic chambers are advocated because the specular scattering models used at present do not appear valid for pyramids that are large compared to the wavelength.

  4. Magnetic field effects on microwave absorbing materials

    NASA Technical Reports Server (NTRS)

    Goldberg, Ira; Hollingsworth, Charles S.; Mckinney, Ted M.

    1991-01-01

    The objective of this program was to gather information to formulate a microwave absorber that can work in the presence of strong constant direct current (DC) magnetic fields. The program was conducted in four steps. The first step was to investigate the electrical and magnetic properties of magnetic and ferrite microwave absorbers in the presence of strong magnetic fields. This included both experimental measurements and a literature survey of properties that may be applicable to finding an appropriate absorbing material. The second step was to identify those material properties that will produce desirable absorptive properties in the presence of intense magnetic fields and determine the range of magnetic field in which the absorbers remain effective. The third step was to establish ferrite absorber designs that will produce low reflection and adequate absorption in the presence of intense inhomogeneous static magnetic fields. The fourth and final step was to prepare and test samples of such magnetic microwave absorbers if such designs seem practical.

  5. Boron-copper neutron absorbing material and method of preparation

    DOEpatents

    Wiencek, Thomas C.; Domagala, Robert F.; Thresh, Henry

    1991-01-01

    A composite, copper clad neutron absorbing material is comprised of copper powder and boron powder enriched with boron 10. The boron 10 content can reach over 30 percent by volume, permitting a very high level of neutron absorption. The copper clad product is also capable of being reduced to a thickness of 0.05 to 0.06 inches and curved to a radius of 2 to 3 inches, and can resist temperatures of 900.degree. C. A method of preparing the material includes the steps of compacting a boron-copper powder mixture and placing it in a copper cladding, restraining the clad assembly in a steel frame while it is hot rolled at 900.degree. C. with cross rolling, and removing the steel frame and further rolling the clad assembly at 650.degree. C. An additional sheet of copper can be soldered onto the clad assembly so that the finished sheet can be cold formed into curved shapes.

  6. Absorbent product and articles made therefrom

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multilayer absorbent product for use in contact with the skin to absorb fluids is described. The product has a water pervious facing layer for contacting the skin, and a first fibrous wicking layer overlaying the water pervious layer. A first container section is defined by inner and outer layers of a water pervious wicking material in between a first absorbent mass and a second container section defined by inner and outer layers of a water pervious wicking material between what is disposed a second absorbent mass, and a liquid impermeable/gas permeable layer overlaying the second fibrous wicking layer.

  7. Nonlinear dynamic vibration absorbers with a saturation

    NASA Astrophysics Data System (ADS)

    Febbo, M.; Machado, S. P.

    2013-03-01

    The behavior of a new type of nonlinear dynamic vibration absorber is studied. A distinctive characteristic of the proposed absorber is the impossibility to extend the system to infinity. The mathematical formulation is based on a finite extensibility nonlinear elastic potential to model the saturable nonlinearity. The absorber is attached to a single degree-of-freedom linear/nonlinear oscillator subjected to a periodic external excitation. In order to solve the equations of motion and to analyze the frequency-response curves, the method of averaging is used. The performance of the FENE absorber is evaluated considering a variation of the nonlinearity of the primary system, the damping and the linearized frequency of the absorber and the mass ratio. The numerical results show that the proposed absorber has a very good efficiency when the nonlinearity of the primary system increases. When compared with a cubic nonlinear absorber, for a large nonlinearity of the primary system, the FENE absorber shows a better effectiveness for the whole studied frequency range. A complete absence of quasi-periodic oscillations is also found for an appropriate selection of the parameters of the absorber. Finally, direct integrations of the equations of motion are performed to verify the accuracy of the proposed method.

  8. Metamaterial absorber with random dendritic cells

    NASA Astrophysics Data System (ADS)

    Zhu, Weiren; Zhao, Xiaopeng

    2010-05-01

    The metamaterial absorber composed of random dendritic cells has been investigated at microwave frequencies. It is found that the absorptivities come to be weaker and the resonant frequency get red shift as the disordered states increasing, however, the random metamaterial absorber still presents high absorptivity more than 95%. The disordered structures can help understanding of the metamaterial absorber and may be employed for practical design of infrared metamaterial absorber, which may play important roles in collection of radiative heat energy and directional transfer enhancement.

  9. Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Laha, S.; Guainazzi, M.; Dewangan, G.; Chakravorty, S.; Kembhavi, A.

    2014-07-01

    We present results from a homogeneous analysis of the broadband 0.3-10 keV CCD resolution as well as of soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. We could put a strict lower limit on the detection fraction of 50%. We find a gap in the distribution of the ionisation parameter in the range 0.5absorber flow is probably constituted by a clumpy distribution of discrete clouds. The distribution of the WA column densities for the sources with broad Fe K-alpha lines are similar to those sources which do not have broadened emission lines. Therefore the detected broad Fe K lines are bonafide and not artefacts of ionised absorption in the soft X-rays. The WA parameters show no correlation among themselves, except for one case. The shallow slope of the logξ versus logv_{out} linear regression (0.12± 0.03) is inconsistent with the scaling laws predicted by radiation or magneto-hydrodynamic-driven winds. Our results suggest also that WA and Ultra Fast Outflows (UFOs) do not represent extreme manifestation of the same astrophysical system.

  10. Device for absorbing mechanical shock

    DOEpatents

    Newlon, C.E.

    1979-08-29

    This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy-absorption capability.

  11. Device for absorbing mechanical shock

    DOEpatents

    Newlon, Charles E.

    1980-01-01

    This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy-absorption capability.

  12. Out in the cold.

    PubMed

    Bates, Jane

    2016-05-04

    Every now and then, you say something to a patient and wonder whether you should have kept quiet. On this occasion, a female patient and I were indulging in a moment of shared empathy over an annoying symptom we both experience - permanently cold feet.

  13. Teaching "In Cold Blood."

    ERIC Educational Resources Information Center

    Berbrich, Joan D.

    1967-01-01

    The Truman Capote nonfiction novel, "In Cold Blood," which reflects for adolescents the immediacy of the real world, illuminates (1) social issues--capital punishment, environmental influence, and the gap between the "haves" and "have-nots," (2) moral issues--the complexity of man's nature, the responsibility of one…

  14. Cold Facts about Viruses.

    ERIC Educational Resources Information Center

    Pea, Celeste; Sterling, Donna R.

    2002-01-01

    Provides ways for students to demonstrate their understanding of scientific concepts and skills. Describes a mini-unit around the cold in which students can relate humans to viruses. Includes activities and a modified simulation that provides questions to guide students. Discusses ways that allows students to apply prior knowledge, take ownership…

  15. Recent Cold War Studies

    ERIC Educational Resources Information Center

    Pineo, Ronn

    2003-01-01

    Cold War historiography has undergone major changes since the 1991 collapse of the Soviet Union. For two years (1992-1993) the principal Soviet archives fell open to scholars, and although some of the richest holdings are now once again closed, new information continues to find its way out. Moreover, critical documentary information has become…

  16. Cold spray nozzle design

    DOEpatents

    Haynes, Jeffrey D.; Sanders, Stuart A.

    2009-06-09

    A nozzle for use in a cold spray technique is described. The nozzle has a passageway for spraying a powder material, the passageway having a converging section and a diverging section, and at least the diverging section being formed from polybenzimidazole. In one embodiment of the nozzle, the converging section is also formed from polybenzimidazole.

  17. Expert Cold Structure Development

    NASA Astrophysics Data System (ADS)

    Atkins, T.; Demuysere, P.

    2011-05-01

    The EXPERT Program is funded by ESA. The objective of the EXPERT mission is to perform a sub-orbital flight during which measurements of critical aero- thermodynamic phenomena will be obtained by using state-of-the-art instrumentation. As part of the EXPERT Flight Segment, the responsibility of the Cold Structure Development Design, Manufacturing and Validation was committed to the Belgian industrial team SONACA/SABCA. The EXPERT Cold Structure includes the Launcher Adapter, the Bottom Panel, the Upper Panel, two Cross Panels and the Parachute Bay. An additional Launcher Adapter was manufactured for the separation tests. The selected assembly definition and manufacturing technologies ( machined parts and sandwich panels) were dictated classically by the mass and stiffness, but also by the CoG location and the sensitive separation interface. Used as support for the various on-board equipment, the Cold Structure is fixed to but thermally uncoupled from the PM 1000 thermal shield. It is protect on its bottom panel by a thermal blanket. As it is a protoflight, analysis was the main tool for the verification. Low level stiffness and modal analysis tests have also been performed on the Cold Structure equipped with its ballast. It allowed to complete its qualification and to prepare SONACA/SABCA support for the system dynamic tests foreseen in 2011. The structure was finally coated with a thermal control black painting and delivered on time to Thales Alenia Space-Italy end of March 201.

  18. The origin of cold gas in giant elliptical galaxies and its role in fuelling radio-mode AGN feedback

    NASA Astrophysics Data System (ADS)

    Werner, N.; Oonk, J. B. R.; Sun, M.; Nulsen, P. E. J.; Allen, S. W.; Canning, R. E. A.; Simionescu, A.; Hoffer, A.; Connor, T.; Donahue, M.; Edge, A. C.; Fabian, A. C.; von der Linden, A.; Reynolds, C. S.; Ruszkowski, M.

    2014-04-01

    The nature and origin of the cold interstellar medium (ISM) in early-type galaxies are still a matter of debate, and understanding the role of this component in galaxy evolution and in fuelling the central supermassive black holes requires more observational constraints. Here, we present a multiwavelength study of the ISM in eight nearby, X-ray and optically bright, giant elliptical galaxies, all central dominant members of relatively low-mass groups. Using far-infrared spectral imaging with the Herschel Photodetector Array Camera & Spectrometer, we map the emission of cold gas in the cooling lines of [C II]λ157 μm, [O I] λ63 μm and [O Ib] λ145 μm. Additionally, we present Hα+[N II] imaging of warm ionized gas with the Southern Astrophysical Research (SOAR) telescope, and a study of the thermodynamic structure of the hot X-ray emitting plasma with Chandra. All systems with extended Hα emission in our sample (6/8 galaxies) display significant [C II] line emission indicating the presence of reservoirs of cold gas. This emission is cospatial with the optical Hα+[N II] emitting nebulae and the lowest entropy soft X-ray emitting plasma. The entropy profiles of the hot galactic atmospheres show a clear dichotomy, with the systems displaying extended emission-line nebulae having lower entropies beyond r ≳ 1 kpc than the cold-gas-poor systems. We show that while the hot atmospheres of the cold-gas-poor galaxies are thermally stable outside of their innermost cores, the atmospheres of the cold-gas-rich systems are prone to cooling instabilities. This provides considerable weight to the argument that cold gas in giant ellipticals is produced chiefly by cooling from the hot phase. We show that cooling instabilities may develop more easily in rotating systems and discuss an alternative condition for thermal instability for this case. The hot atmospheres of cold-gas-rich galaxies display disturbed morphologies indicating that the accretion of clumpy multiphase gas in

  19. Absorbencies of six different rodent beddings: commercially advertised absorbencies are potentially misleading.

    PubMed

    Burn, C C; Mason, G J

    2005-01-01

    Moisture absorbency is one of the most important characteristics of rodent beddings for controlling bacterial growth and ammonia production. However, bedding manufacturers rarely provide information on the absorbencies of available materials, and even when they do, absorption values are usually expressed per unit mass of bedding. Since beddings are usually placed into cages to reach a required depth rather than a particular mass, their volumetric absorbencies are far more relevant. This study therefore compared the saline absorbencies of sawdust, aspen woodchips, two virgin loose pulp beddings (Alpha-Dri and Omega-Dri), reclaimed wood pulp (Tek-Fresh), and corncob, calculated both by volume and by mass. Absorbency per unit volume correlated positively with bedding density, while absorbency per unit mass correlated negatively. Therefore, the relative absorbencies of the beddings were almost completely reversed depending on how absorbency was calculated. By volume, corncob was the most absorbent bedding, absorbing about twice as much saline as Tek-Fresh, the least absorbent bedding. Conversely, when calculated by mass, Tek-Fresh appeared to absorb almost three times as much saline as the corncob. Thus, in practical terms the most absorbent bedding here was corncob, followed by the loose pulp beddings; and this is generally supported by their relatively low ammonia production as seen in previous studies. Many factors other than absorbency determine whether a material is suitable as a rodent bedding, and they are briefly mentioned here. However, manufacturers should provide details of bedding absorbencies in terms of volume, in order to help predict the relative absorbencies of the beddings in practical situations.

  20. An ultrathin dual-band metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Duan, Junping; Zhang, Wendong; Wang, Wanjun; Zhang, Binzhen

    2016-10-01

    The design and preparation of an ultrathin dual-band metamaterial absorber whose resonant frequency located at radar wave (20 GHz-60 GHz) is presented in this paper. The absorber is composed of a 2-D periodic sandwich featured with two concentric annuluses. The influence on the absorber's performance produced by resonant cell's structure size and material parameters was numerically simulated and analyzed based on the standard full wave finite integration technology in CST. Laser ablation process was adopted to prepare the designed absorber on epoxy resin board coated with on double plane of copper with a thickness that is 1/30 and 1/50 of the resonant wavelength at a resonant frequency of 30.51 GHz and 48.15 GHz. The full width at half maximum (FWHM) reached 2.2 GHz and 2.35 GHz and the peak of the absorptance reached 99.977%. The ultrathin absorber is nearly omnidirectional for all polarizations. The test results of prepared sample testify the designed absorber's excellent absorbing performance forcefully. The absorber expands inspirations of radar stealth in military domain due to its flexible design, cost-effective and other outstanding properties.

  1. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A...

  2. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A...

  3. Thermoregulatory modeling for cold stress.

    PubMed

    Xu, Xiaojiang; Tikuisis, Peter

    2014-07-01

    Modeling for cold stress has generated a rich history of innovation, has exerted a catalytic influence on cold physiology research, and continues to impact human activity in cold environments. This overview begins with a brief summation of cold thermoregulatory model development followed by key principles that will continue to guide current and future model development. Different representations of the human body are discussed relative to the level of detail and prediction accuracy required. In addition to predictions of shivering and vasomotor responses to cold exposure, algorithms are presented for thermoregulatory mechanisms. Various avenues of heat exchange between the human body and a cold environment are reviewed. Applications of cold thermoregulatory modeling range from investigative interpretation of physiological observations to forecasting skin freezing times and hypothermia survival times. While these advances have been remarkable, the future of cold stress modeling is still faced with significant challenges that are summarized at the end of this overview.

  4. [Absorbed doses in dental radiology].

    PubMed

    Bianchi, S D; Roccuzzo, M; Albrito, F; Ragona, R; Anglesio, S

    1996-01-01

    The growing use of dento-maxillo-facial radiographic examinations has been accompanied by the publication of a large number of studies on dosimetry. A thorough review of the literature is presented in this article. Most studies were carried out on tissue equivalent skull phantoms, while only a few were in vivo. The aim of the present study was to evaluate in vivo absorbed doses during Orthopantomography (OPT). Full Mouth Periapical Examination (FMPE) and Intraoral Tube Panoramic Radiography (ITPR). Measurements were made on 30 patients, reproducing clinical conditions, in 46 anatomical sites, with 24 intra- and 22 extra-oral thermoluminiscent dosimeters (TLDS). The highest doses were measured, in orthopantomography, at the right mandibular angle (1899 mu Gy) in FMPE on the right naso-labial fold (5640 mu Gy and in ITPR on the palatal surface of the left second upper molar (1936 mu Gy). Intraoral doses ranged from 21 mu Gy, in orthopantomography, to 4494 mu Gy in FMPE. Standard errors ranged from 142% in ITPR to 5% in orthopantomography. The highest rate of standard errors was found in FMPE and ITPR. The data collected in this trial are in agreement with others in major literature reports. Disagreements are probably due to different exam acquisition and data collections. Such differences, presented comparison in several sites, justify lower doses in FMPE and ITPR. Advantages and disadvantages of in vivo dosimetry of the maxillary region are discussed, the former being a close resemblance to clinical conditions of examination and the latter the impossibility of collecting values in depth of tissues. Finally, both ITPR and FMPE required lower doses than expected, and can be therefore reconsidered relative to their radiation risk.

  5. Remedies for Common Cold Symptoms

    PubMed Central

    Miller, Penny F.

    1991-01-01

    Individuals suffering from intolerable symptoms of the common cold can now be advised of safe and effective products for symptomatic relief. This article describes and discusses four categories of drugs used to treat the common cold. To simplify the product selection process for family physicians, suggestions are included for possible ingredients for treatments of specific cold symptoms. PMID:21234087

  6. Human whole body cold adaptation

    PubMed Central

    Daanen, Hein A.M.; Van Marken Lichtenbelt, Wouter D.

    2016-01-01

    ABSTRACT Reviews on whole body human cold adaptation generally do not distinguish between population studies and dedicated acclimation studies, leading to confusing results. Population studies show that indigenous black Africans have reduced shivering thermogenesis in the cold and poor cold induced vasodilation in fingers and toes compared to Caucasians and Inuit. About 40,000 y after humans left Africa, natives in cold terrestrial areas seems to have developed not only behavioral adaptations, but also physiological adaptations to cold. Dedicated studies show that repeated whole body exposure of individual volunteers, mainly Caucasians, to severe cold results in reduced cold sensation but no major physiological changes. Repeated cold water immersion seems to slightly reduce metabolic heat production, while repeated exposure to milder cold conditions shows some increase in metabolic heat production, in particular non-shivering thermogenesis. In conclusion, human cold adaptation in the form of increased metabolism and insulation seems to have occurred during recent evolution in populations, but cannot be developed during a lifetime in cold conditions as encountered in temperate and arctic regions. Therefore, we mainly depend on our behavioral skills to live in and survive the cold. PMID:27227100

  7. Design of a nonlinear torsional vibration absorber

    NASA Astrophysics Data System (ADS)

    Tahir, Ammaar Bin

    Tuned mass dampers (TMD) utilizing linear spring mechanisms to mitigate destructive vibrations are commonly used in practice. A TMD is usually tuned for a specific resonant frequency or an operating frequency of a system. Recently, nonlinear vibration absorbers attracted attention of researchers due to some potential advantages they possess over the TMDs. The nonlinear vibration absorber, or the nonlinear energy sink (NES), has an advantage of being effective over a broad range of excitation frequencies, which makes it more suitable for systems with several resonant frequencies, or for a system with varying excitation frequency. Vibration dissipation mechanism in an NES is passive and ensures that there is no energy backflow to the primary system. In this study, an experimental setup of a rotational system has been designed for validation of the concept of nonlinear torsional vibration absorber with geometrically induced cubic stiffness nonlinearity. Dimensions of the primary system have been optimized so as to get the first natural frequency of the system to be fairly low. This was done in order to excite the dynamic system for torsional vibration response by the available motor. Experiments have been performed to obtain the modal parameters of the system. Based on the obtained modal parameters, the design optimization of the nonlinear torsional vibration absorber was carried out using an equivalent 2-DOF modal model. The optimality criterion was chosen to be maximization of energy dissipation in the nonlinear absorber attached to the equivalent 2-DOF system. The optimized design parameters of the nonlinear absorber were tested on the original 5-DOF system numerically. A comparison was made between the performance of linear and nonlinear absorbers using the numerical models. The comparison showed the superiority of the nonlinear absorber over its linear counterpart for the given set of primary system parameters as the vibration energy dissipation in the former is

  8. Radial cold trap

    DOEpatents

    Grundy, Brian R.

    1981-01-01

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume.

  9. Radial cold trap

    DOEpatents

    Grundy, B.R.

    1981-09-29

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume. 2 figs.

  10. Thin film absorber for a solar collector

    DOEpatents

    Wilhelm, William G.

    1985-01-01

    This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

  11. Cold nuclear fusion

    SciTech Connect

    Tsyganov, E. N.

    2012-02-15

    Recent accelerator experiments on fusion of various elements have clearly demonstrated that the effective cross-sections of these reactions depend on what material the target particle is placed in. In these experiments, there was a significant increase in the probability of interaction when target nuclei are imbedded in a conducting crystal or are a part of it. These experiments open a new perspective on the problem of so-called cold nuclear fusion.

  12. Electronic Equipment Cold Plates

    DTIC Science & Technology

    1976-04-01

    equations for such a flow regiae. For laainar flow and Moderate teaperature differwwe« between the well «nd coolant, a aodifled Sieder -Tate...con- figuration. The heat-transfer coefficients, therefore, were determined by using both the Sieder -Tate and McAdams equations and the coaputed...values used In the analytical predictions. As with th* previous cold Plates, the Sieder -Tate equation gave too low of values for the heat- transfer

  13. Cold Climate Heat Pump

    DTIC Science & Technology

    2013-08-01

    central heating , cooling, and air conditioning (HVAC) system . Both buildings had two zones for heating and cooling, which allowed for a direct...section calls for improved efficiency of mechanical systems as well as an increase of renewable resource usage. Current heating technologies in cold... heated refrigerant is injected into a mixing chamber between the two compressors. The injection leads to a gain in performance of the system through

  14. Cold Stowage Flight Systems

    NASA Technical Reports Server (NTRS)

    Campana, Sharon E.; Melendez, David T.

    2011-01-01

    The International Space Station (ISS) provides a test bed for researchers to perform science experiments in a variety of fields, including human research, life sciences, and space medicine. Many of the experiments being conducted today require science samples to be stored and transported in a temperature controlled environment. NASA provides several systems which aid researchers in preserving their science. On orbit systems provided by NASA include the Minus Eighty Laboratory freezer for ISS (MELFI), Microgravity Experiment Research Locker Incubator (MERLIN), and Glacier. These freezers use different technologies to provide rapid cooling and cold stowage at different temperature levels on board ISS. Systems available to researchers during transportation to and from ISS are MERLIN, Glacier, and Coldbag. Coldbag is a passive cold stowage system that uses phase change materials to maintain temperature. Details of these current technologies are provided along with operational experience gained to date. This paper discusses the capability of the current cold stowage hardware and how it may continue to support NASA s mission on ISS and in future exploration missions.

  15. Cold Stowage Flight Systems

    NASA Technical Reports Server (NTRS)

    Campana, Sharon

    2010-01-01

    The International Space Station (ISS) provides a test bed for researchers to perform science experiments in a variety of fields, including human research, life sciences, and space medicine. Many of the experiments being conducted today require science samples to be stored and transported in a temperature controlled environment. NASA provides several systems which aide researchers in preserving their science. On orbit systems provided by NASA include the Minus Eighty Laboratory freezer for ISS (MELFI), Microgravity Experiment Research Locker Incubator (MERLIN), and Glacier. These freezers use different technologies to provide rapid cooling and cold stowage at different temperature levels on board ISS. Systems available to researchers during transportation to and from ISS are MERLIN, Glacier, and Coldbag. Coldbag is a passive cold stowage system that uses phase change materials. Details of these current technologies will be provided along with operational experience gained to date. With shuttle retirement looming, NASA has protected the capability to provide a temperature controlled environment during transportation to and from the ISS with the use of Glacier and Coldbags, which are compatible with future commercial vehicles including SpaceX's Dragon Capsule, and Orbital s Cygnus vehicle. This paper will discuss the capability of the current cold stowage hardware and how it may continue to support NASA s mission on ISS and in future exploration missions.

  16. The nonlinear piezoelectric tuned vibration absorber

    NASA Astrophysics Data System (ADS)

    Soltani, P.; Kerschen, G.

    2015-07-01

    This paper proposes a piezoelectric vibration absorber, termed the nonlinear piezoelectric tuned vibration absorber (NPTVA), for the mitigation of nonlinear resonances of mechanical systems. The new feature of the NPTVA is that its nonlinear restoring force is designed according to a principle of similarity, i.e., the NPTVA should be an electrical analog of the nonlinear host system. Analytical formulas for the NPTVA parameters are derived using the homotopy perturbation method. Doing so, a nonlinear generalization of Den Hartog’s equal-peak tuning rule is developed for piezoelectric vibration absorbers.

  17. Attenuation of external Bremsstrahlung in metallic absorbers

    SciTech Connect

    Dhaliwal, A.S.; Powar, M.S.; Singh, M. )

    1990-12-01

    In this paper attenuation of bremsstrahlung from {sup 147}Pm and {sup 170}Tm beta emitters has been studied in aluminum, copper, tin, and lead metallic absorbers. Bremsstrahlung spectra and mass attenuation coefficients for monoenergetic gamma rays are used to calculate theoretical attenuation curves. Magnetic deflection and beta stopping techniques are used to measure the integral bremsstrahlung intensities above 30 keV in different target thicknesses. Comparison of measured and calculated attenuation curves shows a good agreement for various absorbers, thus providing a test of this technique, which may be useful in understanding bremsstrahlung intensity buildup and in the design of optimum shielding for bremsstrahlung sources. It is found that the absorption of bremsstrahlung in metallic absorbers does not obey an exponential law and that absorbers act as energy filters.

  18. Energy absorber uses expanded coiled tube

    NASA Technical Reports Server (NTRS)

    Johnson, E. F.

    1972-01-01

    Mechanical shock mitigating device, based on working material to its failure point, absorbs mechanical energy by bending or twisting tubing. It functions under axial or tangential loading, has no rebound, is area independent, and is easy and inexpensive to build.

  19. Neutron absorbing coating for nuclear criticality control

    DOEpatents

    Mizia, Ronald E.; Wright, Richard N.; Swank, William D.; Lister, Tedd E.; Pinhero, Patrick J.

    2007-10-23

    A neutron absorbing coating for use on a substrate, and which provides nuclear criticality control is described and which includes a nickel, chromium, molybdenum, and gadolinium alloy having less than about 5% boron, by weight.

  20. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Milbourne, M.

    2005-01-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. The objective of this task is to quantify lifetimes through measurement of the optical and mechanical stability of candidate polymeric glazing and absorber materials. Polycarbonate sheet glazings, as proposed by two industry partners, have been tested for resistance to UV radiation with three complementary methods. Incorporation of a specific 2-mil thick UV-absorbing screening layer results in glazing lifetimes of at least 15 years; improved screens promise even longer lifetimes. Proposed absorber materials were tested for creep and embrittlement under high temperature, and appear adequate for planned ICS absorbers.

  1. Porous absorber for solar air heaters

    SciTech Connect

    Finch, J.A.

    1980-09-10

    A general discussion of the factors affecting solar collector performance is presented. Bench scale tests done to try to determine the heat transfer characteristics of various screen materials are explained. The design, performance, and evaluation of a crude collector with a simple screen stack absorber is treated. The more sophisticated absorber concept, and its first experimental approximation is examined. A short summary of future plans for the collector concept is included. (MHR)

  2. Multilayer Radar Absorbing Non-Woven Material

    NASA Astrophysics Data System (ADS)

    Dedov, A. V.; Nazarov, V. G.

    2016-06-01

    We study the electrical properties of multilayer radar absorbing materials obtained by adding nonwoven sheets of dielectric fibers with an intermediate layer of electrically conductive carbon fibers. Multilayer materials that absorb electromagnetic radiation in a wide frequency range are obtained by varying the content of the carbon fibers. The carbon-fiber content dependent mechanism of absorption of electromagnetic radiation by sheets and multilayer materials is considered.

  3. Non-absorbed Antibiotics for IBS

    DTIC Science & Technology

    2012-03-16

    absorbed antibiotic rifaximin for nonconstipated irritable bowel syndrome (IBS). This effort adds to the body of literature from other, smaller studies that...have demonstrated clinical efficacy for IBS with rifaximin . Non-absorbed antibiotics have been endorsed by the American College of Gastroenterology... rifaximin 400 mg three times daily for 10 days or placebo. During the initial 2 weeks of therapy and the subsequent 10 weeks of follow-up rifaximin

  4. Structured metal film as a perfect absorber.

    PubMed

    Xiong, Xiang; Jiang, Shang-Chi; Hu, Yu-Hui; Peng, Ru-Wen; Wang, Mu

    2013-08-07

    A new type of absorber, a four-tined fish-spear-like resonator (FFR), constructed by the two-photon polymerization process, is reported. An absorbance of more than 90% is experimentally realized and the resonance occurs in the space between the tines. Since a continuous layer of metallic thin film covers the structure, it is perfectly thermo- and electroconductive, which is the mostly desired feature for many applications.

  5. Radar Absorbing Materials for Cube Stealth Satellite

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Pastore, R.; Vricella, A.; Marchetti, M.

    A Cube Stealth Satellite is proposed for potential applications in defense system. Particularly, the faces of the satellite exposed to the Earth are made of nanostructured materials able to absorb radar surveillance electromagnetic waves, conferring stealth capability to the cube satellite. Microwave absorbing and shielding material tiles are proposed using composite materials consisting in epoxy-resin and carbon nanotubes filler. The electric permittivity of the composite nanostructured materials is measured and discussed. Such data are used by the modeling algorithm to design the microwave absorbing and the shielding faces of the cube satellite. The electromagnetic modeling takes into account for several incidence angles (0-80°), extended frequency band (2-18 GHz), and for the minimization of the electromagnetic reflection coefficient. The evolutionary algorithm used for microwave layered microwave absorber modeling is the recently developed Winning Particle Optimization. The mathematical model of the absorbing structure is finally experimentally validated by comparing the electromagnetic simulation to the measurement of the manufactured radar absorber tile. Nanostructured composite materials manufacturing process and electromagnetic reflection measurements methods are described. Finally, a finite element method analysis of the electromagnetic scattering by cube stealth satellite is performed.

  6. Absorbance changes of carotenoids in different solvents.

    PubMed

    Zang, L Y; Sommerburg, O; van Kuijk, F J

    1997-01-01

    Carotenoids are typically measured in tissues with the high performance liquid chromatography (HPLC) and quantitation is usually done by calibrating with stock solutions in solvents. Four carotenoids including lutein, zeaxanthin, lycopene and beta-carotene were dissolved in hexane and methanol respectively, and their absorbance characteristics were compared. Lutein shows absorbance spectra that are almost independent of solvents at various concentrations. Spectra of zeaxanthin, lycopene and beta-carotene were found to be more solvent-dependent. The absorbance of zeaxanthin at lambda max is about approximately 2 times larger in methanol than in hexane at the higher concentrations, and increased non-linearly with increasing concentration in hexane. The absorbance of lycopene at lambda max in hexane is approximately 4 fold larger than in methanol, but the absorbance of the methanol sample can be recovered by re-extracting this sample in hexane. The absorbance of beta-carotene in hexane is larger than in methanol, and increased linearly with increasing concentration. But beta-carotene showed a non-linear concentration effect in methanol. There are very small variations in lambda max for all four carotenoids between hexane and methanol, due to differences in molar extinction coefficients. The non-linear concentration effects for these carotenoids are probably due to differences in solubility leading to the formation of microcrystals. Thus, care should be taken with quantitation of tissue carotenoid values, when they depend on measurement of concentrations in stock solutions.

  7. Perfect terahertz absorber using fishnet based metafilm

    SciTech Connect

    Azad, Abul Kalam; Shchegolkov, Dmitry Yu; Chen, Houtong; Taylor, Antoinette; Smirnova, E I; O' Hara, John F

    2009-01-01

    We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unity at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.

  8. Cold streams in early massive hot haloes as the main mode of galaxy formation.

    PubMed

    Dekel, A; Birnboim, Y; Engel, G; Freundlich, J; Goerdt, T; Mumcuoglu, M; Neistein, E; Pichon, C; Teyssier, R; Zinger, E

    2009-01-22

    Massive galaxies in the young Universe, ten billion years ago, formed stars at surprising intensities. Although this is commonly attributed to violent mergers, the properties of many of these galaxies are incompatible with such events, showing gas-rich, clumpy, extended rotating disks not dominated by spheroids. Cosmological simulations and clustering theory are used to explore how these galaxies acquired their gas. Here we report that they are 'stream-fed galaxies', formed from steady, narrow, cold gas streams that penetrate the shock-heated media of massive dark matter haloes. A comparison with the observed abundance of star-forming galaxies implies that most of the input gas must rapidly convert to stars. One-third of the stream mass is in gas clumps leading to mergers of mass ratio greater than 1:10, and the rest is in smoother flows. With a merger duty cycle of 0.1, three-quarters of the galaxies forming stars at a given rate are fed by smooth streams. The rarer, submillimetre galaxies that form stars even more intensely are largely merger-induced starbursts. Unlike destructive mergers, the streams are likely to keep the rotating disk configuration intact, although turbulent and broken into giant star-forming clumps that merge into a central spheroid. This stream-driven scenario for the formation of discs and spheroids is an alternative to the merger picture.

  9. The Isis cold moderators

    SciTech Connect

    Allen, G. M.; Broome, T. A.; Burridge, R. A.; Cragg, D.; Hall, R.; Haynes, D.; Hirst, J.; Hogston, J. R.; Jones, H. H.; Sexton, J.; Wright, P.

    1997-09-01

    ISIS is a pulsed spallation neutron source where neutrons are produced by the interaction of a 160 kW proton beam of energy 800 MeV in a water-cooled Tantalum Target. The fast neutrons produced are thermalized in four moderators: two ambient water, one liquid methane operating at 100K and a liquid hydrogen moderator at 20 K. This paper gives a description of the construction of both cold moderator systems, details of the operating experience and a description of the current development program.

  10. Paroxysmal cold hemoglobinuria.

    PubMed

    Shanbhag, Satish; Spivak, Jerry

    2015-06-01

    Paroxysmal cold hemoglobinuria is a rare cause of autoimmune hemolytic anemia predominantly seen as an acute form in young children after viral illnesses and in a chronic form in some hematological malignancies and tertiary syphilis. It is a complement mediated intravascular hemolytic anemia associated with a biphasic antibody against the P antigen on red cells. The antibody attaches to red cells at colder temperatures and causes red cell lysis when blood recirculates to warmer parts of the body. Treatment is mainly supportive and with red cell transfusion, but immunosuppressive therapy may be effective in severe cases.

  11. Cold Fusion Verification.

    DTIC Science & Technology

    1991-03-01

    published work, talking with others in the field, and attending conferences, that CNF probably is chimera and will go the way of N-rays and polywater ...way of N-rays and polywater . To date, no one, including Pons and Fleischmann, has been able to construct a so-called CNF electrochemical cell that...Cold Nuclear Fusion (CNF), as originally reported in 1989. The conclusion is that CNF probably is chimera and will go the way of N-rays and polywater

  12. Cardiovascular responses to cold exposure.

    PubMed

    Sun, Zhongjie

    2010-01-01

    The prevalence of hypertension is increased in winter and in cold regions of the world. Cold temperatures make hypertension worse and trigger cardiovascular complications (stroke, myocardial infarction, heart failure, etc.). Chronic or intermittent exposure to cold causes hypertension and cardiac hypertrophy in animals. The purpose of this review is to provide the recent advances in the mechanistic investigation of cold-induced hypertension (CIH). Cold temperatures increase the activities of the sympathetic nervous system (SNS) and the renin-angiotensin system (RAS). The SNS initiates CIH via the RAS. Cold exposure suppresses the expression of eNOS and formation of NO, increases the production of endothelin-1 (ET-1), up-regulates ETA receptors, but down-regulates ETB receptors. The roles of these factors and their relations in CIH will be reviewed.

  13. Cardiovascular responses to cold exposure

    PubMed Central

    Sun, Zhongjie

    2010-01-01

    The prevalence of hypertension is increased in winter and in cold regions of the world. Cold temperatures make hypertension worse and trigger cardiovascular complications (stroke, myocardial infarction, heart failure, etc.). Chronic or intermittent exposure to cold causes hypertension and cardiac hypertrophy in animals. The purpose of this review is to provide the recent advances in the mechanistic investigation of cold-induced hypertension (CIH). Cold temperatures increase the activities of the sympathetic nervous system (SNS) and the renin-angiotensin system (RAS). The SNS initiates CIH via the RAS. Cold exposure suppresses the expression of eNOS and formation of NO, increases the production of endothelin-1 (ET-1), up-regulates ETA receptors, but down-regulates ETB receptors. The roles of these factors and their relations in CIH will be reviewed. PMID:20036896

  14. Method of absorbance correction in a spectroscopic heating value sensor

    SciTech Connect

    Saveliev, Alexei; Jangale, Vilas Vyankatrao; Zelepouga, Sergeui; Pratapas, John

    2013-09-17

    A method and apparatus for absorbance correction in a spectroscopic heating value sensor in which a reference light intensity measurement is made on a non-absorbing reference fluid, a light intensity measurement is made on a sample fluid, and a measured light absorbance of the sample fluid is determined. A corrective light intensity measurement at a non-absorbing wavelength of the sample fluid is made on the sample fluid from which an absorbance correction factor is determined. The absorbance correction factor is then applied to the measured light absorbance of the sample fluid to arrive at a true or accurate absorbance for the sample fluid.

  15. Idiopathic cold urticaria and anaphylaxis.

    PubMed

    Işk, Sakine; Arkan-Ayyldz, Zeynep; Sozmen, Sule Caglayan; Karaman, Özkan; Uzuner, Nevin

    2014-01-01

    Cold urticaria (CU) is a subtype of physical urticaria characterized by the development of urticaria and angioedema after cold exposure. Symptoms typically occur minutes after skin exposure to cold air, liquids, and objects. Most common method to confirm the diagnosis of CU is through ice cube challenge test, but 20% of patients with CU have negative ice cube challenge test results. The greatest risk with this kind of urticaria is the development of systemic reaction resulting in a hemodynamic collapse during generalized cold exposure. We report a case of a patient who developed CU and anaphylaxis during swimming and diving in the sea.

  16. Warm Absorber Diagnostics of AGN Dynamics

    NASA Astrophysics Data System (ADS)

    Kallman, Timothy

    Warm absorbers and related phenomena are observable manifestations of outflows or winds from active galactic nuclei (AGN) that have great potential value. Understanding AGN outflows is important for explaining the mass budgets of the central accreting black hole, and also for understanding feedback and the apparent co-evolution of black holes and their host galaxies. In the X-ray band warm absorbers are observed as photoelectric absorption and resonance line scattering features in the 0.5-10 keV energy band; the UV band also shows resonance line absorption. Warm absorbers are common in low luminosity AGN and they have been extensively studied observationally. They may play an important role in AGN feedback, regulating the net accretion onto the black hole and providing mechanical energy to the surroundings. However, fundamental properties of the warm absorbers are not known: What is the mechanism which drives the outflow?; what is the gas density in the flow and the geometrical distribution of the outflow?; what is the explanation for the apparent relation between warm absorbers and the surprising quasi-relativistic 'ultrafast outflows' (UFOs)? We propose a focused set of model calculations that are aimed at synthesizing observable properties of warm absorber flows and associated quantities. These will be used to explore various scenarios for warm absorber dynamics in order to answer the questions in the previous paragraph. The guiding principle will be to examine as wide a range as possible of warm absorber driving mechanisms, geometry and other properties, but with as careful consideration as possible to physical consistency. We will build on our previous work, which was a systematic campaign for testing important class of scenarios for driving the outflows. We have developed a set of tools that are unique and well suited for dynamical calculations including radiation in this context. We also have state-of-the-art tools for generating synthetic spectra, which are

  17. Water absorbency by wool fibers: Hofmeister effect.

    PubMed

    Lo Nostro, Pierandrea; Fratoni, Laura; Ninham, Barry W; Baglioni, Piero

    2002-01-01

    Wool is a complex material, composed of cuticle and epicuticle cells, surrounded by a cell membrane complex. Wool fibers absorb moisture from air, and, once immersed in water, they take up considerable amounts of liquid. The water absorbency parameter can be determined from weight gain, according to a standard method, and used to quantify this phenomenon. In this paper we report a study on the water absorbency (or retention) of untreated wool fibers in the presence of aqueous 1 M salt solutions at 29 degrees C and a relative humidity of either 33% or 56%. The effect of anions was determined by selecting a wide range of different sodium salts, while the effect of cations was checked through some chlorides and nitrates. Our results show a significant specific ion and ion pair "Hofmeister" effects, that change the amount of water absorbed by the fibers. To understand this phenomenon, the water absorbency parameter (A(w)) is compared to different physicochemical parameters such as the lyotropic number, free energy of hydration of ions, molar surface tension increment, polarizability, refractive index increment, and molar refractivity. The data indicate that this Hofmeister phenomenon is controlled by dispersion forces that depend on the polarizability of ionic species, their adsorption frequencies, the solvent, and the substrate. These dispersion forces dominate the behavior in concentrated solutions. They are in accord with new developing theories of solutions and molecular interactions in colloidal systems that account for Hofmeister effects.

  18. Oxygen absorbers in food preservation: a review.

    PubMed

    Cichello, Simon Angelo

    2015-04-01

    The preservation of packaged food against oxidative degradation is essential to establish and improve food shelf life, customer acceptability, and increase food security. Oxygen absorbers have an important role in the removal of dissolved oxygen, preserving the colour, texture and aroma of different food products, and importantly inhibition of food spoilage microbes. Active packaging technology in food preservation has improved over decades mostly due to the sealing of foods in oxygen impermeable package material and the quality of oxygen absorber. Ferrous iron oxides are the most reliable and commonly used oxygen absorbers within the food industry. Oxygen absorbers have been transformed from sachets of dried iron-powder to simple self-adhesive patches to accommodate any custom size, capacity and application. Oxygen concentration can be effectively lowered to 100 ppm, with applications spanning a wide range of food products and beverages across the world (i.e. bread, meat, fish, fruit, and cheese). Newer molecules that preserve packaged food materials from all forms of degradation are being developed, however oxygen absorbers remain a staple product for the preservation of food and pharmaceutical products to reduce food wastage in developed nations and increased food security in the developing & third world.

  19. Non-Absorbable Gas Behavior in the Absorber/Evaporator of a Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Nagamoto, Wataru; Sugiyama, Takahide

    A two-dimensional numerical study on non-absorbable gas behavior in the absorber/evaporator of an absorption chiller has been performed. In the present study, the effect of the pitch-to-diameter ratio of a cylinder bundle in the absorber was highlighted. From the results, a sudden decrease of the overall heat transfer coefficient of the absorber was observed at a certain mean concentration of non-absorbable gas for each pitch-to-diameter ratio. Such a critical concentration was also found to decrease as the pitch-to- diameter ratio increased. The sudden decrease occurs due to the sudden disappearance of recirculating region, which is formed between the absorber and the evaporator, and where most of non-absorbable gas stays when it exists. As the pitch-to-diameter ratio increases, the recirculating region becomes weak because the velocity of the high velocity region supporting the recirculating flow decreases. Then, the critical mean concentration of non-absorbable gas is found to decrease as pitch-to-ratio increases.

  20. A strained silicon cold electron bolometer using Schottky contacts

    SciTech Connect

    Brien, T. L. R. Ade, P. A. R.; Barry, P. S.; Dunscombe, C.; Morozov, D. V.; Sudiwala, R. V.; Leadley, D. R.; Myronov, M.; Parker, E. H. C.; Prest, M. J.; Whall, T. E.; Prunnila, M.; Mauskopf, P. D.

    2014-07-28

    We describe optical characterisation of a strained silicon cold electron bolometer (CEB), operating on a 350 mK stage, designed for absorption of millimetre-wave radiation. The silicon cold electron bolometer utilises Schottky contacts between a superconductor and an n{sup ++} doped silicon island to detect changes in the temperature of the charge carriers in the silicon, due to variations in absorbed radiation. By using strained silicon as the absorber, we decrease the electron-phonon coupling in the device and increase the responsivity to incoming power. The strained silicon absorber is coupled to a planar aluminium twin-slot antenna designed to couple to 160 GHz and that serves as the superconducting contacts. From the measured optical responsivity and spectral response, we calculate a maximum optical efficiency of 50% for radiation coupled into the device by the planar antenna and an overall noise equivalent power, referred to absorbed optical power, of 1.1×10{sup −16} W Hz{sup −1/2} when the detector is observing a 300 K source through a 4 K throughput limiting aperture. Even though this optical system is not optimized, we measure a system noise equivalent temperature difference of 6 mK Hz{sup −1/2}. We measure the noise of the device using a cross-correlation of time stream data, measured simultaneously with two junction field-effect transistor amplifiers, with a base correlated noise level of 300 pV Hz{sup −1/2} and find that the total noise is consistent with a combination of photon noise, current shot noise, and electron-phonon thermal noise.

  1. Optical analysis of solar energy tubular absorbers.

    PubMed

    Saltiel, C; Sokolov, M

    1982-11-15

    The energy absorbed by a solar energy tubular receiver element for a single incident ray is derived. Two types of receiver elements were analyzed: (1) an inner tube with an absorbing coating surrounded by a semitransparent cover tube, and (2) a semitransparent inner tube filled with an absorbing fluid surrounded by a semitransparent cover tube. The formation of ray cascades in the semitransparent tubes is considered. A numerical simulation to investigate the influence of the angle of incidence, sizing, thickness, and coefficient of extinction of the tubes was performed. A comparison was made between receiver elements with and without cover tubes. Ray tracing analyses in which rays were followed within the tubular receiver element as well as throughout the rest of the collector were performed for parabolic and circular trough concentrating collectors.

  2. Interference theory of metamaterial perfect absorbers.

    PubMed

    Chen, Hou-Tong

    2012-03-26

    The impedance matching to free space in metamaterial perfect absorbers has been believed to involve and rely on magnetic resonant response, with direct evidence provided by the anti-parallel surface currents in the metal structures. Here I present a different theoretical interpretation based on interference, which shows that the two layers of metal structures in metamaterial absorbers are linked only by multiple reflections with negligible near-field interactions or magnetic resonances. This is further supported by the out-of-phase surface currents derived at the interfaces of resonator array and ground plane through multiple reflections and superpositions. The theory developed here explains all features observed in narrowband metamaterial absorbers and therefore provides a profound understanding of the underlying physics.

  3. Translatory shock absorber for attitude sensors

    NASA Technical Reports Server (NTRS)

    Vonpragenau, G. L.; Morgan, I. T., Jr.; Kirby, C. A. (Inventor)

    1976-01-01

    A translatory shock absorber is provided for mounting an attitude sensor thereon for isolating a sensor from translatory vibrations. The translatory shock absorber includes a hollow block structure formed as one piece to form a parallelogram. The absorber block structure includes a movable top plate for supporting the attitude sensor and a fixed base plate with opposed side plates interposed between. At the junctions of the side plates, and the base and top plates, there are provided grooves which act as flexible hinges for attenuating translatory vibrations. A damping material is supported on a pedestal which is carried on the base plate between the side plates thereof. The top of the damping material rests against the bottom surface of the top plate for eliminating the resonant peaks of vibration.

  4. Absorber Materials at Room and Cryogenic Temperatures

    SciTech Connect

    F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun

    2011-09-01

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  5. Ferrite HOM Absorber for the RHIC ERL

    SciTech Connect

    Hahn,H.; Choi, E.M.; Hammons, L.

    2008-10-01

    A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

  6. Experiments in cold fusion

    SciTech Connect

    Palmer, E.P.

    1986-03-28

    The work of Steve Jones and others in muon-catalyzed cold fusion of deuterium and hydrogen suggests the possibility of such fusion catalyzed by ions, or combinations of atoms, or more-or-less free electrons in solid and liquid materials. A hint that this might occur naturally comes from the heat generated in volcanic action in subduction zones on the earth. It is questionable whether the potential energy of material raised to the height of a midocean ridge and falling to the depth of an ocean trench can produce the geothermal effects seen in the volcanoes of subduction zones. If the ridge, the trench, the plates, and the asthenosphere are merely visible effects of deeper density-gradient driven circulations, it is still uncertain that observed energy-concentration effects fit the models.

  7. Cold isopressing method

    DOEpatents

    Chen, Jack C.; Stawisuck, Valerie M.; Prasad, Ravi

    2003-01-01

    A cold isopressing method in which two or more layers of material are formed within an isopressing mold. One of the layers consists of a tape-cast film. The layers are isopressed within the isopressing mold, thereby to laminate the layers and to compact the tape-cast film. The isopressing mold can be of cylindrical configuration with the layers being coaxial cylindrical layers. The materials used in forming the layers can contain green ceramic materials and the resultant structure can be fired and sintered as necessary and in accordance with known methods to produce a finished composite, ceramic structure. Further, such green ceramic materials can be of the type that are capable of conducting hydrogen or oxygen ions at high temperature with the object of utilizing the finished composite ceramic structure as a ceramic membrane element.

  8. Optimization and engineering of microwave absorbers

    NASA Astrophysics Data System (ADS)

    Chen, Kuo-Liang

    1998-12-01

    In this thesis, a concerted effort has been made to study and evaluate the individual electromagnetic properties of the absorbing components including carbon black, conducting fibers, metal flakes, magnetic materials such as carbonyl iron, ferrite and the chiral type of micro- carbon coil. The study of the electromagnetic properties covers functions such as dielectric dissipation, random scattering effect at low and high frequencies, magnetic dissipation at high frequencies and also the effect of chirality for different angles of incidence. The results of these studies have been used in the design, engineering and optimization of the microwave absorbers. The objective of this thesis is to identify the absorption mechanism of each of various type of fillers and to study the synergic effect arising from a combination of these in a non-metallic host medium. This will help us in producing microwave absorbers suitable for broad band application with the advantages of light weight, having high strength and possessing good chemical resistance. The results from experimental measurements of various material combinations have been greatly influenced by the theoretical understanding of the absorption mechanism. Design of microwave absorbers is governed by the requirement of the users as well as the characteristics of the objects (targets) inferred by theoretical understanding and experimental data to arrive at the right formula. Finally a detailed quality control program has to be charted out reflecting both the electromagnetic as well as mechanical properties. This is done by carrying out the tests systematically on small samples and then proceeding to practical absorbers making use of the data compiled earlier on smaller samples. In this thesis, to modify all dielectric absorbing components including micro-carbon chirals to reduce the sensitivity of absorption for different incident angles is unprecedented topic.

  9. Absorber topography dependence of phase edge effects

    NASA Astrophysics Data System (ADS)

    Shanker, Aamod; Sczyrba, Martin; Connolly, Brid; Waller, Laura; Neureuther, Andy

    2015-10-01

    Mask topography contributes to phase at the wafer plane, even for OMOG binary masks currently in use at the 22nm node in deep UV (193nm) lithography. Here, numerical experiments with rigorous FDTD simulation are used to study the impact of mask 3D effects on aerial imaging, by varying the height of the absorber stack and its sidewall angle. Using a thin mask boundary layer model to fit to rigorous simulations it is seen that increasing the absorber thickness, and hence the phase through the middle of a feature (bulk phase) monotonically changes the wafer-plane phase. Absorber height also influences best focus, revealed by an up/down shift in the Bossung plot (linewidth vs. defocus). Bossung plot tilt, however, responsible for process window variability at the wafer, is insensitive to changes in the absorber height (and hence also the bulk phase). It is seen to depend instead on EM edge diffraction from the thick mask edge (edge phase), but stays constant for variations in mask thickness within a 10% range. Both bulk phase and edge phase are also independent of sidewall angle fluctuation, which is seen to linearly affect the CD at the wafer, but does not alter wafer phase or the defocus process window. Notably, as mask topography varies, the effect of edge phase can be replicated by a thin mask model with 8nm wide boundary layers, irrespective of absorber height or sidewall angle. The conclusions are validated with measurements on phase shifting masks having different topographic parameters, confirming the strong dependence of phase variations at the wafer on bulk phase of the mask absorber.

  10. Nonfreezing Cold-Induced Injuries

    DTIC Science & Technology

    2012-01-01

    circumstances. This chapter explores the history, epidemiology , pathophysiology, and current prevention and treatments of NFCI, as well as pernio...environment should mean that NFCI is preventable in most circumstances. This chapter explores the history, epidemiology , pathophysi- ology, and current...prevention and treatments of NFCI, as well as pernio (chilblains), cryoglobulinemia, and cold urticaria. Epidemiology Individuals suffering cold

  11. Quantum walk with one variable absorbing boundary

    NASA Astrophysics Data System (ADS)

    Wang, Feiran; Zhang, Pei; Wang, Yunlong; Liu, Ruifeng; Gao, Hong; Li, Fuli

    2017-01-01

    Quantum walks constitute a promising ingredient in the research on quantum algorithms; consequently, exploring different types of quantum walks is of great significance for quantum information and quantum computation. In this study, we investigate the progress of quantum walks with a variable absorbing boundary and provide an analytical solution for the escape probability (the probability of a walker that is not absorbed by the boundary). We simulate the behavior of escape probability under different conditions, including the reflection coefficient, boundary location, and initial state. Moreover, it is also meaningful to extend our research to the situation of continuous-time and high-dimensional quantum walks.

  12. OSCEE fan exhaust bulk absorber treatment evaluation

    NASA Technical Reports Server (NTRS)

    Bloomer, H. E.; Samanich, N. E.

    1980-01-01

    The acoustic suppression capability of bulk absorber material designed for use in the fan exhaust duct walls of the quiet clean short haul experiment engine (OCSEE UTW) was evaluated. The acoustic suppression to the original design for the engine fan duct which consisted of phased single degree-of-freedom wall treatment was tested with a splitter and also with the splitter removed. Peak suppression was about as predicted with the bulk absorber configuration, however, the broadband characteristics were not attained. Post test inspection revealed surface oil contamination on the bulk material which could have caused the loss in bandwidth suppression.

  13. Analysis of Energy-Absorbing Foundations.

    DTIC Science & Technology

    1978-12-15

    1ENN51YVAN&A 5TATL UNIV UNIVERSITY PARK DEPT OF ENGI-CYTC F/S 13/h ANALYSIS OF ENERGY -ABSORBING POUNDATIONS.(U) ECC 78 V H NEUBERT, S Ji YIN DNA01-78...C-0036 UNCLASSIFIED DNA-48OFP NL "M~ENOMOEE MIflfl END ______ 1 32 112.2 MICROCOPY RILSOLUTION TEST CHIART LELL ,NA 480 MIL ANALYSIS OF ENERGY ...8217 REPORT & PERIOD COVERED Final Report for Period ANALYSIS OF ENERGY -ABSORBING FOUNDATIONS I Dee 77-1S Dee 78 6. PERFORMING ORG, REPORT NUMBER 7AUTHOR

  14. Shock-Absorbent Ball-Screw Mechanism

    NASA Technical Reports Server (NTRS)

    Hirr, Otto A., Jr.; Meneely, R. W.

    1986-01-01

    Actuator containing two ball screws in series employs Belleville springs to reduce impact loads, thereby increasing life expectancy. New application of springs increases reliability of equipment in which ball screws commonly used. Set of three springs within lower screw of ball-screw mechanism absorbs impacts that result when parts reach their upper and lower limits of movement. Mechanism designed with Belleville springs as shock-absorbing elements because springs have good energy-to-volume ratio and easily stacked to attain any stiffness and travel.

  15. Radio-Absorbing Nanocoatings on Corrugated Surfaces

    NASA Astrophysics Data System (ADS)

    Antipov, V. B.; Potekaev, A. I.; Vorozhtsov, A. B.; Melentyev, S. V.; Tsyganok, Yu. I.

    2016-12-01

    The feasibility of producing protective radio-absorbing shielding materials on the basis of differently shaped surfaces with nanostructured coatings is investigated. Combinations of special nanostructured materials and technical solutions for the shape of the absorbing surface were tested, in order to create efficient nanocoatings. It is shown that the coatings of interest that meet the requirements of low reflection and high attenuation of transmitted radiation combined with low coating thickness can be developed, using corrugated surfaces. Corrugated chicken egg-packing cell samples with nanostructured carbon coatings were examined and found to allow for effective shielding of electromagnetic radiation and to exhibit minimum reflection coefficients as compared to construction materials.

  16. Timing the warm absorber in NGC 4051

    NASA Astrophysics Data System (ADS)

    Silva, C. V.; Uttley, P.; Costantini, E.

    2016-12-01

    We investigated, using spectral-timing analysis, the characterization of highly ionized outflows in Seyfert galaxies, the so-called warm absorbers. Here, we present our results of the extensive 600 ks of XMM-Newton archival observations of the bright and highly variable Seyfert 1 galaxy NGC 4051 whose spectrum has revealed a complex multicomponent wind. Making use of both RGS and EPIC-pn data, we performed a detailed analysis through a time-dependent photoionization code in combination with spectral and Fourier spectral-timing techniques. The source light curves and the warm absorber parameters obtained from the data were used to simulate the response of the gas to variations in the ionizing flux of the central source. The resulting time variable spectra were employed to predict the effects of the warm absorber on the time lags and coherence of the energy dependent light curves. We have found that, in the absence of any other lag mechanisms, a warm absorber with the characteristics of the one observed in NGC 4051, is able to produce soft lags, up to 100 s, on timescales of hours. The time delay is associated with the response of the gas to changes in the ionizing source, either by photoionization or radiative recombination, which is dependent on its density. The range of radial distances that, under our assumptions, yield longer time delays are distances r 0.3-1.0 × 1016 cm, and hence gas densities n 0.4-3.0 × 107 cm-3. Since these ranges are comparable to the existing estimates of the location of the warm absorber in NGC 4051, we suggest that it is likely that the observed X-ray time lags may carry a signature of the warm absorber response time to changes in the ionizing continuum. Our results show that the warm absorber in NGC 4051 does not introduce lags on the short timescales associated with reverberation, but will likely modify the hard continuum lags seen on longer timescales, which in this source have been measured to be on the order of 50 s. Hence, these

  17. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Lindquist, C.; Milbourne, M.

    2005-11-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. We have begun evaluation of several new UV-screened polycarbonate sheet glazing constructions. This has involved interactions with several major polymer industry companies to obtain improved candidate samples. Proposed absorber materials were tested for UV resistance, and appear adequate for unglazed ICS absorbers.

  18. 21 CFR 880.6025 - Absorbent tipped applicator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Absorbent tipped applicator. 880.6025 Section 880... Devices § 880.6025 Absorbent tipped applicator. (a) Identification. An absorbent tipped applicator is a device intended for medical purposes that consists of an absorbent swab on a wooden, paper, or...

  19. The Cooling of a Liquid Absorber using a Small Cooler

    SciTech Connect

    Baynham, D.E.; Bradshaw, T.W.; Green, M.A.; Ishimoto, S.; Liggins, N.

    2005-08-24

    This report discusses the use of small cryogenic coolers for cooling the Muon Ionization Cooling Experiment (MICE) liquid cryogen absorbers. Since the absorber must be able contain liquid helium as well liquid hydrogen, the characteristics of the available 4.2 K coolers are used here. The issues associated with connecting two-stage coolers to liquid absorbers are discussed. The projected heat flows into an absorber and the cool-down of the absorbers using the cooler are presented. The warm-up of the absorber is discussed. Special hydrogen safety issues that may result from the use of a cooler on the absorbers are also discussed.

  20. Cold-Weather Sports and Your Family

    MedlinePlus

    ... Feeding Your 1- to 2-Year-Old Cold-Weather Sports and Your Family KidsHealth > For Parents > Cold- ... once the weather turns frosty. Beating the Cold-Weather Blahs Once a chill is in the air, ...

  1. Cough and Cold Medicine Abuse (For Parents)

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old Cough and Cold Medicine Abuse KidsHealth > For Parents > Cough ... cough and cold medicine. Why Do Kids Abuse Cough and Cold Remedies? Before the U.S. Food and ...

  2. Tunable metamaterial dual-band terahertz absorber

    NASA Astrophysics Data System (ADS)

    Luo, C. Y.; Li, Z. Z.; Guo, Z. H.; Yue, J.; Luo, Q.; Yao, G.; Ji, J.; Rao, Y. K.; Li, R. K.; Li, D.; Wang, H. X.; Yao, J. Q.; Ling, F. R.

    2015-11-01

    We report a design of a temperature controlled tunable dual band terahertz absorber. The compact single unit cell consists of two nested closed square ring resonators and a layer metallic separated by a substrate strontium titanate (STO) dielectric layer. It is found that the absorber has two distinctive absorption peaks at frequencies 0.096 THz and 0.137 THz, whose peaks are attained 97% and 75%. Cooling the absorber from 400 K to 250 K causes about 25% and 27% shift compared to the resonance frequency of room temperature, when we cooling the temperature to 150 K, we could attained both the two tunabilities exceeding 53%. The frequency tunability is owing to the variation of the dielectric constant of the low-temperature co-fired ceramic (LTCC) substrate. The mechanism of the dual band absorber is attributed to the overlapping of dual resonance frequencies, and could be demonstrated by the distributions of the electric field. The method opens up avenues for designing tunable terahertz devices in detection, imaging, and stealth technology.

  3. Methods of calculating radiation absorbed dose.

    PubMed

    Wegst, A V

    1987-01-01

    The new tumoricidal radioactive agents being developed will require a careful estimate of radiation absorbed tumor and critical organ dose for each patient. Clinical methods will need to be developed using standard imaging or counting instruments to determine cumulated organ activities with tracer amounts before the therapeutic administration of the material. Standard MIRD dosimetry methods can then be applied.

  4. Moving core beam energy absorber and converter

    DOEpatents

    Degtiarenko, Pavel V.

    2012-12-18

    A method and apparatus for the prevention of overheating of laser or particle beam impact zones through the use of a moving-in-the-coolant-flow arrangement for the energy absorbing core of the device. Moving of the core spreads the energy deposition in it in 1, 2, or 3 dimensions, thus increasing the effective cooling area of the device.

  5. Composition for absorbing hydrogen from gas mixtures

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Lee, Myung W.

    1999-01-01

    A hydrogen storage composition is provided which defines a physical sol-gel matrix having an average pore size of less than 3.5 angstroms which effectively excludes gaseous metal hydride poisons while permitting hydrogen gas to enter. The composition is useful for separating hydrogen gas from diverse gas streams which may have contaminants that would otherwise render the hydrogen absorbing material inactive.

  6. Shock absorbing mount for electrical components

    NASA Technical Reports Server (NTRS)

    Dillon, R. F., Jr.; Mayne, R. C. (Inventor)

    1975-01-01

    A shock mount for installing electrical components on circuit boards is described. The shock absorber is made of viscoelastic material which interconnects the electrical components. With this system, shocks imposed on one component of the circuit are not transmitted to other components. A diagram of a typical circuit is provided.

  7. How to build a molecular shock absorber.

    PubMed

    McGough, A

    1999-12-02

    Newly determined structures of the alpha-helical repeats that make up the key 'rod' domains of spectrin and alpha-actinin - which serve as spacers between their actin-binding domains - have provided important insights into how these proteins function as molecular shock absorbers in cells.

  8. Novel shock absorber features varying yield strengths

    NASA Technical Reports Server (NTRS)

    Geier, D. J.

    1964-01-01

    A shock absorbent webbing of partially drawn synthetic strands is arranged in sections of varying density related to the varying mass of the human body. This is contoured to protect the body at points of contact, when subjected to large acceleration or deceleration forces.

  9. Shock absorber protects motive components against overloads

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Shock absorber with an output shaft, hollow gear, and a pair of springs forming a resilient driving connection between shaft and gear, operates when abnormally high torques are applied. This simple durable frictional device is valuable in rotating mechanisms subject to sudden overloads.

  10. Torus elements used in effective shock absorber

    NASA Technical Reports Server (NTRS)

    Cunningham, P.; Platus, D. L.

    1966-01-01

    Energy absorbing device forces torus elements to revolve annularly between two concentric tubes when a load is applied to one tube. Interference forces can be varied by using torus elements of different thicknesses. The device operates repeatedly in compression or tension, and under problems of large onset rate tolerance or structural overload.

  11. Aldehyde-containing urea-absorbing polysaccharides

    NASA Technical Reports Server (NTRS)

    Mueller, W. A.; Hsu, G. C.; Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A novel aldehyde containing polymer (ACP) is prepared by reaction of a polysaccharide with periodate to introduce aldehyde groups onto the C2 - C3 carbon atoms. By introduction of ether and ester groups onto the pendant primary hydroxyl solubility characteristics are modified. The ACP is utilized to absorb nitrogen bases such as urea in vitro or in vivo.

  12. Integrated tuned vibration absorbers: a theoretical study.

    PubMed

    Gardonio, Paolo; Zilletti, Michele

    2013-11-01

    This article presents a simulation study on two integrated tuned vibration absorbers (TVAs) designed to control the global flexural vibration of lightly damped thin structures subject to broad frequency band disturbances. The first one consists of a single axial switching TVA composed by a seismic mass mounted on variable axial spring and damper elements so that the characteristic damping and natural frequency of the absorber can be switched iteratively to control the resonant response of three flexural modes of the hosting structure. The second one consists of a single three-axes TVA composed by a seismic mass mounted on axial and rotational springs and dampers, which are arranged in such a way that the suspended mass is characterized by uncoupled heave and pitch-rolling vibrations. In this case the three damping and natural frequency parameters of the absorber are tuned separately to control three flexural modes of the hosting structure. The simulation study shows that the proposed single-unit absorbers produce, respectively, 5.3 and 8.7 dB reductions of the global flexural vibration of a rectangular plate between 20 and 120 Hz.

  13. Metamaterial Absorber Based Multifunctional Sensor Application

    NASA Astrophysics Data System (ADS)

    Ozer, Z.; Mamedov, A. M.; Ozbay, E.

    2017-02-01

    In this study metamaterial based (MA) absorber sensor, integrated with an X-band waveguide, is numerically and experimentally suggested for important application including pressure, density sensing and marble type detecting applications based on rectangular split ring resonator, sensor layer and absorber layer that measures of changing in the dielectric constant and/or the thickness of a sensor layer. Changing of physical, chemical or biological parameters in the sensor layer can be detected by measuring the resonant frequency shifting of metamaterial absorber based sensor. Suggested MA based absorber sensor can be used for medical, biological, agricultural and chemical detecting applications in microwave frequency band. We compare the simulation and experimentally obtained results from the fabricated sample which are good agreement. Simulation results show that the proposed structure can detect the changing of the refractive indexes of different materials via special resonance frequencies, thus it could be said that the MA-based sensors have high sensitivity. Additionally due to the simple and tiny structures it could be adapted to other electronic devices in different sizes.

  14. Imaging of Damped Ly-alpha Absorbers

    NASA Astrophysics Data System (ADS)

    Jim, K. T. C.; Roth, K. C.

    1998-05-01

    Intervening H I gas clouds toward QSOs give rise to damped Ly-alpha absorption. Because of the high column density (N(H I)>= 2*E(20) cm(-2) ) these systems have been thought to be galactic disks in some stage of formation. However, because potential optical counterparts have not been identified for most damped Ly-alpha systems, it is possible that some of the absorbing systems could be dwarf irregular galaxies or low surface brightness galaxies, and are thus difficult to image. In any case, the absorbers are expected to have small angular separation from the QSOs, and so high resolution imaging is required to differentiate the absorbers from the QSOs. Because previous studies have not shown any dominant morphological form for the few candidate objects known, our images are obtained with the Hawaii tip-tilt system in order to achieve the best possible morphological classification. By imaging in the NIR and optical bands that bracket the 4000 Angstroms break of these Ly-alpha absorbers, we can more readily select candidate objects by photometrically constraining their redshifts. In our sample of 14 QSOs with abosorbers from 1absorbers (Kolhatkar et al.)

  15. Absorbed fractions for electrons in ellipsoidal volumes

    NASA Astrophysics Data System (ADS)

    Amato, E.; Lizio, D.; Baldari, S.

    2011-01-01

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as 90Y and to 131I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  16. Absorbed fractions for electrons in ellipsoidal volumes.

    PubMed

    Amato, E; Lizio, D; Baldari, S

    2011-01-21

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as (90)Y and to (131)I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  17. Cold urticaria and celiac disease.

    PubMed

    Pedrosa Delgado, M; Martín Muñoz, F; Polanco Allué, I; Martín Esteban, M

    2008-01-01

    Cold urticaria can be associated with blood and thyroid disorders, drugs, or infections. Celiac disease is an autoimmune enteropathy caused by permanent gluten intolerance. It is often associated with other autoimmune diseases, such as chronic idiopathic urticaria. Nevertheless, association with cold urticaria has not yet been described. A boy aged 3 years 8 months presented local urticaria-angioedema when exposed to cold temperatures. An ice cube test was positive and iron deficiency anemia was demonstrated. He later developed legume intolerance, rhinoconjunctivitis related to pollen sensitization, and asthma. Due to persistence of cold urticaria symptoms and refractory anemia, a test for immunoglobulin A autoantibodies to tissue transglutaminase and an intestinal biopsy were performed. Results of both tests were compatible with celiac disease.A study of human leukocyte antigen indicated a high risk phenotype (HLA, DR6/DR7; DQA 0501, 0201; DQB 0301, 0201). After 7 months of a gluten-free diet, the boy's anemia resolved and he is free of symptoms when exposed to cold. This is a first description of the possibility of an association between celiac disease and cold urticaria. A poor course of cold urticaria in the absence of evidence of another underlying condition should lead to suspicion of celiac disease.

  18. Cold Fusion, A Journalistic Investigation

    NASA Astrophysics Data System (ADS)

    Krivit, Steven B.

    2005-03-01

    Author of the recent book, The Rebirth of Cold Fusion, and founder of New Energy Times, Steven B. Krivit presents a summary of cold fusion's, past, present and possible future. This talk will briefly review five highlights of the recent New Energy Times investigation into cold fusion research:1. Analysis of early studies that supposedly disproved cold fusion.2. Key early corroborations that supported the claims of Fleischmann and Pons.3. The evolving understanding of cold fusion reaction paths and by-products.4. A look at volumetric power density.5. Brief comparison of the progress in hot fusion research as compared to cold fusion research.New Energy Times, founded in 2000, is an independent communications company which currently specializes in reporting on cold fusion researchootnotetextReferences and copies of the presentation are available at www.newenergytimes.com/reports/aps2005.htmhttp://www.newenergytimes.com/reports/aps2005.htm. It has no affiliations with any organization, entity or party which invests in these technologies, nor any individual researcher or research facility.

  19. Neutron absorbers and methods of forming at least a portion of a neutron absorber

    SciTech Connect

    Guillen, Donna P; Porter, Douglas L; Swank, W David; Erickson, Arnold W

    2014-12-02

    Methods of forming at least a portion of a neutron absorber include combining a first material and a second material to form a compound, reducing the compound into a plurality of particles, mixing the plurality of particles with a third material, and pressing the mixture of the plurality of particles and the third material. One or more components of neutron absorbers may be formed by such methods. Neutron absorbers may include a composite material including an intermetallic compound comprising hafnium aluminide and a matrix material comprising pure aluminum.

  20. Cold fusion studies

    NASA Astrophysics Data System (ADS)

    Hembree, D. M.; Burchfield, L. A.; Fuller, E. L., Jr.; Perey, F. G.; Mamantov, G.

    1990-06-01

    A series of experiments designed to detect the by-products expected from deuterium fusion occurring in the palladium and titanium cathodes of heavy water, D2O, electrolysis cells is reported. The primary purpose of this account is to outline the integrated experimental design developed to test the cold fusion hypothesis and to report preliminary results that support continuing the investigation. Apparent positive indicators of deuterium fusion were observed, but could not be repeated or proved to originate from the electrochemical cells. In one instance, two large increases in the neutron count rate, the largest of which exceeded the background by 27 standard deviations, were observed. In a separate experiment, one of the calorimetry cells appeared to be producing approximately 18 percent more power that the input value, but thermistor failure prevented an accurate recording of the event as a function of time. In general, the tritium levels in most cells followed the slow enrichment expected from the electrolysis of D2O containing a small amount of tritium. However, after 576 hours of electrolysis, one cell developed a tritium concentration approximately seven times greater than expected level.

  1. Cold fusion verification

    NASA Astrophysics Data System (ADS)

    North, M. H.; Mastny, G. F.; Wesley, E. J.

    1991-03-01

    The objective of this work to verify and reproduce experimental observations of Cold Nuclear Fusion (CNF), as originally reported in 1989. The method was to start with the original report and add such additional information as became available to build a set of operational electrolytic CNF cells. Verification was to be achieved by first observing cells for neutron production, and for those cells that demonstrated a nuclear effect, careful calorimetric measurements were planned. The authors concluded, after laboratory experience, reading published work, talking with others in the field, and attending conferences, that CNF probably is chimera and will go the way of N-rays and polywater. The neutron detector used for these tests was a completely packaged unit built into a metal suitcase that afforded electrostatic shielding for the detectors and self-contained electronics. It was battery-powered, although it was on charge for most of the long tests. The sensor element consists of He detectors arranged in three independent layers in a solid moderating block. The count from each of the three layers as well as the sum of all the detectors were brought out and recorded separately. The neutron measurements were made with both the neutron detector and the sample tested in a cave made of thick moderating material that surrounded the two units on the sides and bottom.

  2. Versatile cold atom target apparatus

    SciTech Connect

    Goetz, Simone; Hoeltkemeier, Bastian; Hofmann, Christoph S.; Litsch, Dominic; DePaola, Brett D.; Weidemueller, Matthias

    2012-07-15

    We report on a compact and transportable apparatus that consists of a cold atomic target at the center of a high resolution recoil ion momentum spectrometer. Cold rubidium atoms serve as a target which can be operated in three different modes: in continuous mode, consisting of a cold atom beam generated by a two-dimensional magneto-optical trap, in normal mode in which the atoms from the beam are trapped in a three-dimensional magneto-optical trap (3D MOT), and in high density mode in which the 3D MOT is operated in dark spontaneous optical trap configuration. The targets are characterized using photoionization.

  3. Plants in a cold climate.

    PubMed Central

    Smallwood, Maggie; Bowles, Dianna J

    2002-01-01

    Plants are able to survive prolonged exposure to sub-zero temperatures; this ability is enhanced by pre-exposure to low, but above-zero temperatures. This process, known as cold acclimation, is briefly reviewed from the perception of cold, through transduction of the low-temperature signal to functional analysis of cold-induced gene products. The stresses that freezing of apoplastic water imposes on plant cells is considered and what is understood about the mechanisms that plants use to combat those stresses discussed, with particular emphasis on the role of the extracellular matrix. PMID:12171647

  4. Spectral absorbance of benthic cladoceran carapaces as a new method for inferring past UV exposure of aquatic biota

    NASA Astrophysics Data System (ADS)

    Nevalainen, Liisa; Rautio, Milla

    2014-01-01

    We developed a method for measuring fossil cladoceran (Branchiopoda) carapace absorbance to infer past ultraviolet radiation (UV) exposure in lakes. This was done under the presumptions that cladocerans synthesize photoprotective compounds, of which melanin is the main UV-absorbing pigment, to their exoskeletons and melanin is preserved in sedimentary cladoceran remains. We extracted large-sized cladoceran (benthic Alona spp.) carapaces from subsections of sediment cores from two environmentally divergent lakes; a humic boreal forest lake in eastern Finland (past 1500 years) and a clear-water mountain lake in the Austrian Alps (past 300 years). We measured the absorbance of extracted carapaces with a spectrophotometer under visible light and UV wavelengths using an adapter, which was designed to hold the microfossils. When compared to the spectrum of synthetic melanin, the shapes of absorbance spectra at the 700-280 nm range suggested that the fossil carapaces contained melanin. The carapace absorbance under UV throughout the sediment cores was significantly higher in the clear-water alpine lake than in the humic boreal lake reflecting differences in the general underwater UV and optical environments between the sites. In addition, carapace absorbance was significantly higher during the Little Ice Age (LIA) than during pre- or post-LIA periods in both lakes. In the alpine lake, this was most likely a response to increased underwater UV induced by reduced primary production and more transparent water column during the cold summers of LIA, whereas reduced input of carbon compounds from the catchment through elongated permafrost and ice-cover periods likely induced higher water transparency in the boreal lake during this cold climate phase. We conclude that fossil melanin provides a good estimation of past underwater UV exposure in lakes with large cladoceran carapaces preserved in sediments and that the method introduced here is easy and cost- and time

  5. Cold-electron bolometers for future mm and sub-mm sky surveys

    NASA Astrophysics Data System (ADS)

    Salatino, Maria; de Bernardis, Paolo; Mahashabde, Sumedh; Kuzmin, Leonid S.; Masi, Silvia

    2014-07-01

    Future sky surveys in the mm/sub-mm range, like the forthcoming balloon-borne missions LSPE, OLIMPO, SPIDER etc., will need detectors insensitive to cosmic rays (CRs) and with a NEP of the order of 10-17 ¥ 10-18 W/sqrt(Hz). The Cold-Electron Bolometers (CEBs) technology is promising, having the required proper- ties, since the absorber volume is extremely small and the electron system of the absorber is thermally insulated from the phonon system. We have developed an experimental setup to test the optical performance and the CRs insensitivity of CEBs, with the target of integrating them in the OLIMPO and LSPE focal planes.

  6. Absorbed dose thresholds and absorbed dose rate limitations for studies of electron radiation effects on polyetherimides

    NASA Technical Reports Server (NTRS)

    Long, Edward R., Jr.; Long, Sheila Ann T.; Gray, Stephanie L.; Collins, William D.

    1989-01-01

    The threshold values of total absorbed dose for causing changes in tensile properties of a polyetherimide film and the limitations of the absorbed dose rate for accelerated-exposure evaluation of the effects of electron radiation in geosynchronous orbit were studied. Total absorbed doses from 1 kGy to 100 MGy and absorbed dose rates from 0.01 MGy/hr to 100 MGy/hr were investigated, where 1 Gy equals 100 rads. Total doses less than 2.5 MGy did not significantly change the tensile properties of the film whereas doses higher than 2.5 MGy significantly reduced elongation-to-failure. There was no measurable effect of the dose rate on the tensile properties for accelerated electron exposures.

  7. Design of a non-traditional dynamic vibration absorber.

    PubMed

    Cheung, Y L; Wong, W O

    2009-08-01

    A non-traditional dynamic vibration absorber is proposed for the minimization of maximum vibration velocity response of a vibrating structure. Unlike the traditional damped absorber configuration, the proposed absorber has a linear viscous damper connecting the absorber mass directly to the ground instead of the main mass. Optimum parameters of the proposed absorber are derived based on the fixed-point theory for minimizing the maximum vibration velocity response of a single-degree-of-freedom system under harmonic excitation. The extent of reduction in maximum vibration velocity response of the primary system when using the traditional dynamic absorber is compared with that using the proposed one. Under the optimum tuning condition of the absorbers, it is proved analytically that the proposed absorber provides a greater reduction in maximum vibration velocity response of the primary system than the traditional absorber.

  8. ANS cold source neutronics analysis

    SciTech Connect

    Lillie, R.A.

    1994-06-01

    This paper describes the calculational procedures employed in the ongoing neutronics analysis of the ANS cold source and presents in chronological order some of the more important results from the one- and two-dimensional discrete calculations performed to date in support of the ANS cold source design. In particular, cold neutron currents from cryostat shapes which can be adequately modeled with two-dimensional geometries are compared with and without reentrant cavities. Also, results are presented from one-dimensional comparative liquid hydrogen vs liquid deuterium calculations in which the density, placement, and para-ortho mixture of liquid hydrogen is investigated. In addition, the evolution of the ANS conceptual design cold source from an initial short cylindrical cryostat with hemispherical upper and lower heads employing a natural convection liquid deuterium circulation system to the final spherical design employing a pumped system is described. Finally, performance data and heating rates are presented for some possible alternate ANS cryostat and vacuum jacket materials.

  9. Prescription Drugs and Cold Medicines

    MedlinePlus

    ... Alerts Alcohol Club Drugs Cocaine Hallucinogens Heroin Inhalants Marijuana MDMA (Ecstasy/Molly) Methamphetamine Opioids Prescription Drugs & Cold ... and over-the-counter (OTC) drugs are, after marijuana (and alcohol), the most commonly abused substances by ...

  10. Cold nuclear fusion

    NASA Astrophysics Data System (ADS)

    Tsyganov, E. N.; Bavizhev, M. D.; Buryakov, M. G.; Dabagov, S. B.; Golovatyuk, V. M.; Lobastov, S. P.

    2015-07-01

    If target deuterium atoms were implanted in a metal crystal in accelerator experiments, a sharp increase in the probability of DD-fusion reaction was clearly observed when compared with the reaction's theoretical value. The electronic screening potential, which for a collision of free deuterium atoms is about 27 eV, reached 300-700 eV in the case of the DD-fusion in metallic crystals. These data leads to the conclusion that a ban must exist for deuterium atoms to be in the ground state 1s in a niche filled with free conduction electrons. At the same time, the state 2p whose energy level is only 10 eV above that of state 1s is allowed in these conditions. With anisotropy of 2p, 3p or above orbitals, their spatial positions are strictly determined in the lattice coordinate system. When filling out the same potential niches with two deuterium atoms in the states 2p, 3p or higher, the nuclei of these atoms can be permanently positioned without creating much Coulomb repulsion at a very short distance from each other. In this case, the transparency of the potential barrier increases dramatically compared to the ground state 1s for these atoms. The probability of the deuterium nuclei penetrating the Coulomb barrier by zero quantum vibration of the DD-system also increases dramatically. The so-called cold nuclear DD-fusion for a number of years was registered in many experiments, however, was still rejected by mainstream science for allegedly having no consistent scientific explanation. Finally, it received the validation. Below, we outline the concept of this explanation and give the necessary calculations. This paper also considers the further destiny of the formed intermediate state of 4He∗.

  11. Cold regions hydrology and hydraulics

    SciTech Connect

    Ryan, W.L. ); Crissman, R.D. )

    1990-01-01

    This monograph addresses a narrow aspect of cold regions engineering, namely the effects of cold weather on the traditional civil engineering disciplines of hydrology and hydraulics. Hydrologic and hydraulic considerations in the design, construction, and operation of civil works are very important. Many of the problems encountered in the design and construction of buildings, transportation systems, water supply facilities, waste treatment facilities, and hazardous waste disposal facilities, for example are closely tied to the characteristics of the site hydrology.

  12. Cold urticaria and HIV infection.

    PubMed

    Lin, R Y; Schwartz, R A

    1993-10-01

    Three patients, all seropositive for HIV antibody, complained of swelling and pruritus on the head and limbs when exposed to the cold. All three had received zidovudine for significant CD4 cell depletion, but had no AIDS-defining illnesses. An ice-cube test was positive on each individual. There was no evidence of cold agglutinins, cryoglobulins, syphilis, or other concurrent diseases in any of the patients. This association may represent yet another allergic manifestation in HIV infection.

  13. Imaging highly absorbing nanoparticles using photothermal microscopy

    NASA Astrophysics Data System (ADS)

    Lussier, Simon-Alexandre; Moradi, Hamid; Price, Alain; Murugkar, Sangeeta

    2015-03-01

    Gold nanoparticles (NPs) have tremendous potential in biomedicine. They can be used as absorbing labels inside living cells for the purpose of biomedical imaging, biosensing as well as for photothermal therapy. We demonstrate photothermal imaging of highly-absorbing particles using a pump-probe setup. The photothermal signal is recovered by heterodyne detection, where the excitation pump laser is at 532 nm and the probe laser is at 638 nm. The sample is moved by a scanning stage. Proof of concept images of red polystyrene microspheres and gold nanoparticles are obtained with this home-built multimodal microscope. The increase in temperature at the surface of the gold NPs, due to the pump laser beam, can be directly measured by means of this photothermal microscope and then compared with the results from theoretical predictions. This technique will be useful for characterization of nanoparticles of different shapes, sizes and materials that are used in cancer diagnosis and therapy.

  14. Impedance matched thin metamaterials make metals absorbing

    PubMed Central

    Mattiucci, N.; Bloemer, M. J.; Aközbek, N.; D'Aguanno, G.

    2013-01-01

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin (<1 micron), polarization independent, extremely efficient absorbers (in principle being capable to reach A > 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others. PMID:24220284

  15. A sound absorbing metasurface with coupled resonators

    NASA Astrophysics Data System (ADS)

    Li, Junfei; Wang, Wenqi; Xie, Yangbo; Popa, Bogdan-Ioan; Cummer, Steven A.

    2016-08-01

    An impedance matched surface is able, in principle, to totally absorb the incident sound and yield no reflection, and this is desired in many acoustic applications. Here we demonstrate a design of impedance matched sound absorbing surface with a simple construction. By coupling different resonators and generating a hybrid resonance mode, we designed and fabricated a metasurface that is impedance-matched to airborne sound at tunable frequencies with subwavelength scale unit cells. With careful design of the coupled resonators, over 99% energy absorption at central frequency of 511 Hz with a 50% absorption bandwidth of 140 Hz is achieved experimentally. The proposed design can be easily fabricated, and is mechanically stable. The proposed metasurface can be used in many sound absorption applications such as loudspeaker design and architectural acoustics.

  16. Absorbing Software Testing into the Scrum Method

    NASA Astrophysics Data System (ADS)

    Tuomikoski, Janne; Tervonen, Ilkka

    In this paper we study, how to absorb software testing into the Scrum method. We conducted the research as an action research during the years 2007-2008 with three iterations. The result showed that testing can and even should be absorbed to the Scrum method. The testing team was merged into the Scrum teams. The teams can now deliver better working software in a shorter time, because testing keeps track of the progress of the development. Also the team spirit is higher, because the Scrum team members are committed to the same goal. The biggest change from test manager’s point of view was the organized Product Owner Team. Test manager don’t have testing team anymore, and in the future all the testing tasks have to be assigned through the Product Backlog.

  17. The ultimate chrome absorber in photomask making

    NASA Astrophysics Data System (ADS)

    Hashimoto, Masahiro; Iwashita, Hiroyuki; Kominato, Atsushi; Shishido, Hiroaki; Ushida, Masao; Mitsui, Hideaki

    2008-05-01

    193nm-immersion lithography is the most promising technology for 32nm-node device fabrication. A new Cr absorber (TFC) for 193-nm attenuated phase-shift blanks was developed to meet the photomask requirements without any additional process step, such as hardmask etching. TFC was introduced with a design concept of the vertical profile for shorter etching time, the over etching time reduction. As a result, the dry-etching time was dramatically improved by more than 20% shorter than the conventional Cr absorber (TF11) without any process changes. We confirmed that 150nm-resist thickness was possible by TFC. The 32nm technology-node requirement is fully supported by TFC with thinner CAR, such as resolution and CD performance.

  18. Accelerated life testing of solar absorber coatings

    NASA Astrophysics Data System (ADS)

    Carlsson, Bo; Moeller, K.; Frei, Ulrich; Koehl, Michael

    1994-09-01

    Results from a comprehensive case study on accelerated life testing of some selective solar collector absorber coatings for DHW systems are reviewed. The study was conducted within Task X `Solar Materials Research and Development' of the IEA Solar Heating and Cooling Program from 1987 to 1992 and is unique due to its quantitative and systematic approach for durability assessment. The work of case study involved the development of both experimental and theoretical tools to aid the assessment of service life or absorber coatings. This entailed performance analysis, failure analysis, microclimate characterization, environmental resistance testing and life date analysis. Predicted in-service degradation of coatings from accelerated life testing was found to be in fairly good agreement both qualitatively and quantitatively with what was actually observed on coatings installed and tested for three years in solar collectors working under typical DHW conditions.

  19. Fault Detection for Automotive Shock Absorber

    NASA Astrophysics Data System (ADS)

    Hernandez-Alcantara, Diana; Morales-Menendez, Ruben; Amezquita-Brooks, Luis

    2015-11-01

    Fault detection for automotive semi-active shock absorbers is a challenge due to the non-linear dynamics and the strong influence of the disturbances such as the road profile. First obstacle for this task, is the modeling of the fault, which has been shown to be of multiplicative nature. Many of the most widespread fault detection schemes consider additive faults. Two model-based fault algorithms for semiactive shock absorber are compared: an observer-based approach and a parameter identification approach. The performance of these schemes is validated and compared using a commercial vehicle model that was experimentally validated. Early results shows that a parameter identification approach is more accurate, whereas an observer-based approach is less sensible to parametric uncertainty.

  20. Investigations on Absorber Materials at Cryogenic Temperatures

    SciTech Connect

    Marhauser, Frank; Elliott, Thomas; Rimmer, Robert

    2009-05-01

    In the framework of the 12 GeV upgrade project for the Continuous Electron Beam Accelerator Facility (CEBAF) improvements are being made to refurbish cryomodules housing Thomas Jefferson National Accelerator Facility's (JLab) original 5-cell cavities. Recently we have started to look into a possible simplification of the existing Higher Order Mode (HOM) absorber design combined with the aim to find alternative material candidates. The absorbers are implemented in two HOM-waveguides immersed in the helium bath and operate at 2 K temperature. We have built a cryogenic setup to perform measurements on sample load materials to investigate their lossy characteristics and variations from room temperature down to 2 K. Initial results are presented in this paper.

  1. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Y.W.; Wiedermann, A.H.; Ockert, C.E.

    1983-08-26

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  2. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Yong W.; Wiedermann, Arne H.; Ockert, Carl E.

    1985-01-01

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  3. Vibration absorber modeling for handheld machine tool

    NASA Astrophysics Data System (ADS)

    Abdullah, Mohd Azman; Mustafa, Mohd Muhyiddin; Jamil, Jazli Firdaus; Salim, Mohd Azli; Ramli, Faiz Redza

    2015-05-01

    Handheld machine tools produce continuous vibration to the users during operation. This vibration causes harmful effects to the health of users for repeated operations in a long period of time. In this paper, a dynamic vibration absorber (DVA) is designed and modeled to reduce the vibration generated by the handheld machine tool. Several designs and models of vibration absorbers with various stiffness properties are simulated, tested and optimized in order to diminish the vibration. Ordinary differential equation is used to derive and formulate the vibration phenomena in the machine tool with and without the DVA. The final transfer function of the DVA is later analyzed using commercial available mathematical software. The DVA with optimum properties of mass and stiffness is developed and applied on the actual handheld machine tool. The performance of the DVA is experimentally tested and validated by the final result of vibration reduction.

  4. Disposable Diaper Absorbency: Improvements via Advanced Designs.

    PubMed

    Helmes, C Tucker; O'Connor, Robert; Sawyer, Larry; Young, Sharon

    2014-08-01

    Absorbency effectiveness in diapers has improved significantly in recent years with the advent of new ingredient combinations and advanced design features. With these features, many leading products maintain their dryness performance overnight. Considering the importance of holding liquid away from the skin, ongoing research in diaper construction focuses on strategies to increase the effectiveness to capture liquid and help avoid rewetting of infant skin. The layout and design of a disposable diaper allows for distribution of absorbency features where they can provide the optimal benefit. Clinical evidence indicates materials can keep moisture away from the skin in the diapered area, helping maintain proper skin hydration, minimizing irritation, and contributing to reduced rates of diaper rash.

  5. Biomolecular Effects of Cold Plasma Exposure

    NASA Technical Reports Server (NTRS)

    Mogul, Rakesh; Bolshakov, Alexander A.; Chan, Suzanne L.; Stevens, Ramsey D.; Khare, Bishun N.; Meyyappan, M.; Trent, Jonathan D.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    The effects of cold plasma exposure on Deinococcus radiodurans, plasmid DNA and model proteins were assessed using microbiological, spectrometric and biochemical techniques. Exposure of D. radiodurans, an extremely radiation resistant microbe, to O2 plasma (less than or equal to 25 W, approx. 45 mTorr, 90 min) yielded a approx. 99.999 % sterilization and the sterilization rate was increased approx. 10-fold at 100 W and 500 mTorr. AFM images shows that the exposed cells are significantly deformed and possess 50-70 nm concavities. IR analysis indicates the chemical degradation of lipids, proteins and carotenoids of the cell wall and membrane. Intracellular damage was indicated by major absorbance loss at 1245, 1651 and 1538/cm corresponding to degradation of DNA and proteins, respectively. Biochemical experiments demonstrate that plasmas induce strand scissions and crosslinking of plasmid DNA, and reduction of enzyme activity; the degradation is power dependent with total sample loss occurring in 60 s at 200 W and 500 mTorr. Emission spectroscopy shows that D. radiodurans is volatilized into CO2, CO, N2 and H2O confirming the removal of biological matter from contaminated surfaces. The O2 plasma impacts several cellular components predominantly through chemical degradation by atomic oxygen. A CO2, plasma, however, was not effective at degrading D. radiodurans, revealing the importance of plasma composition, which has implications for planetary protection and the contamination of Mars.

  6. Wide band cryogenic ultra-high vacuum microwave absorber

    DOEpatents

    Campisi, I.E.

    1992-05-12

    An absorber waveguide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the waveguide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the waveguide. 11 figs.

  7. Wide band cryogenic ultra-high vacuum microwave absorber

    DOEpatents

    Campisi, Isidoro E.

    1992-01-01

    An absorber wave guide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the wave guide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the wave guide.

  8. Tech Transfer Webinar: Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2016-07-12

    A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  9. Metamaterial Resonant Absorbers for Terahertz Sensing

    DTIC Science & Technology

    2015-12-01

    and their periodic nature , finite element (FE) modeling is the preferable means of designing metamaterials. In order to use metamaterials in sensors ...will incorporate the metamaterial absorber design of this research into a more efficient, cost effective, bi-material THz sensor that can be employed...in a variety of naval applications. 14. SUBJECT TERMS terahertz sensors , metamaterials, uncooled detectors 15. NUMBER OF PAGES 73 16

  10. Lightweight Energy Absorbers for Blast Containers

    NASA Technical Reports Server (NTRS)

    Balles, Donald L.; Ingram, Thomas M.; Novak, Howard L.; Schricker, Albert F.

    2003-01-01

    Kinetic-energy-absorbing liners made of aluminum foam have been developed to replace solid lead liners in blast containers on the aft skirt of the solid rocket booster of the space shuttle. The blast containers are used to safely trap the debris from small explosions that are initiated at liftoff to sever frangible nuts on hold-down studs that secure the spacecraft to a mobile launch platform until liftoff.

  11. Design and Manufacture of Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2016-07-12

    Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  12. Tech Transfer Webinar: Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-06-17

    A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  13. Design and Manufacture of Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-05-28

    Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  14. Shock wave absorber having a deformable liner

    DOEpatents

    Youngdahl, C.K.; Wiedermann, A.H.; Shin, Y.W.; Kot, C.A.; Ockert, C.E.

    1983-08-26

    This invention discloses a shock wave absorber for a piping system carrying liquid. The absorber has a plastically deformable liner defining the normal flow boundary for an axial segment of the piping system, and a nondeformable housing is spaced outwardly from the liner so as to define a gas-tight space therebetween. The flow capacity of the liner generally corresponds to the flow capacity of the piping system line, but the liner has a noncircular cross section and extends axially of the piping system line a distance between one and twenty times the diameter thereof. Gas pressurizes the gas-tight space equal to the normal liquid pressure in the piping system. The liner has sufficient structural capacity to withstand between one and one-half and two times this normal liquid pressures; but at greater pressures it begins to plastically deform initially with respect to shape to a more circular cross section, and then with respect to material extension by circumferentially stretching the wall of the liner. A high energy shock wave passing through the liner thus plastically deforms the liner radially into the gas space and progressively also as needed in the axial direction of the shock wave to minimize transmission of the shock wave beyond the absorber.

  15. Microscopic modeling of nitride intersubband absorbance

    NASA Astrophysics Data System (ADS)

    Montano, Ines; Allerman, A. A.; Wierer, J. J.; Moseley, M.; Skogen, E. J.; Tauke-Pedretti, A.; Vawter, G. A.

    III-nitride intersubband structures have recently attracted much interest because of their potential for a wide variety of applications ranging from electro-optical modulators to terahertz quantum cascade lasers. To overcome present simulation limitations we have developed a microscopic absorbance simulator for nitride intersubband devices. Our simulator calculates the band structure of nitride intersubband systems using a fully coupled 8x8 k.p Hamiltonian and determines the material response of a single period in a density-matrix-formalism by solving the Heisenberg equation including many-body and dephasing contributions. After calculating the polarization due to intersubband transitions in a single period, the resulting absorbance of a superlattice structure including radiative coupling between the different periods is determined using a non-local Green's-function formalism. As a result our simulator allows us to predict intersubband absorbance of superlattice structures with microscopically determined lineshapes and linewidths accounting for both many-body and correlation contributions. This work is funded by Sandia National Laboratories Laboratory Directed Research and Development program. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin.

  16. COSMIC DUST IN Mg II ABSORBERS

    SciTech Connect

    Menard, Brice; Fukugita, Masataka

    2012-08-01

    Mg II absorbers induce reddening on background quasars. We measure this effect and infer the cosmic density of dust residing in these systems to be {Omega} Almost-Equal-To 2 Multiplication-Sign 10{sup -6}, in units of the critical density of the universe, which is comparable to the amount of dust found in galactic disks or about half the amount inferred to exist outside galaxies. We also estimate the neutral hydrogen abundance in Mg II clouds to be {Omega} Almost-Equal-To 1.5 Multiplication-Sign 10{sup -4}, which is approximately 5% of hydrogen in stars in galaxies. This implies a dust-to-gas mass ratio for Mg II clouds of about 1/100, which is similar to the value for normal galaxies. This would support the hypothesis of the outflow origin of Mg II clouds, which are intrinsically devoid of stars and hence have no sources of dust. Considerations of the dust abundance imply that the presence of Mg II absorbers around galaxies lasts effectively for a few Gyr. High-redshift absorbers allow us to measure the rest-frame extinction curve to 900 A, at which the absorption by the Lyman edge dominates over scattering by dust in the extinction opacity.

  17. Heaving buoys, point absorbers and arrays.

    PubMed

    Falnes, Johannes; Hals, Jørgen

    2012-01-28

    Absorption of wave energy may be considered as a phenomenon of interference between incident and radiated waves generated by an oscillating object; a wave-energy converter (WEC) that displaces water. If a WEC is very small in comparison with one wavelength, it is classified as a point absorber (PA); otherwise, as a 'quasi-point absorber'. The latter may be a dipole-mode radiator, for instance an immersed body oscillating in the surge mode or pitch mode, while a PA is so small that it should preferably be a source-mode radiator, for instance a heaving semi-submerged buoy. The power take-off capacity, the WEC's maximum swept volume and preferably also its full physical volume should be reasonably matched to the wave climate. To discuss this matter, two different upper bounds for absorbed power are applied in a 'Budal diagram'. It appears that, for a single WEC unit, a power capacity of only about 0.3 MW matches well to a typical offshore wave climate, and the full physical volume has, unfortunately, to be significantly larger than the swept volume, unless phase control is used. An example of a phase-controlled PA is presented. For a sizeable wave-power plant, an array consisting of hundreds, or even thousands, of mass-produced WEC units is required.

  18. Load limiting energy absorbing lightweight debris catcher

    NASA Technical Reports Server (NTRS)

    Kahn, Jon B. (Inventor); Schneider, William C. (Inventor)

    1991-01-01

    In the representative embodiment of the invention disclosed, a load limiting, energy absorbing net is arranged to overlay a normally-covered vent opening in the rear bulkhead of the space orbiter vehicle. Spatially-disposed flexible retainer straps are extended from the net and respectively secured to bulkhead brackets spaced around the vent opening. The intermediate portions of the straps are doubled over and stitched together in a pattern enabling the doubled-over portions to progressively separate at a predicable load designed to be well below the tensile capability of the straps as the stitches are successively torn apart by the forces imposed on the retainer members whenever the cover plate is explosively separated from the bulkhead and propelled into the net. By arranging these stitches to be successively torn away at a load below the strap strength in response to forces acting on the retainers that are less than the combined strength of the retainers, this tearing action serves as a predictable compact energy absorber for safely halting the cover plate as the retainers are extended as the net is deployed. The invention further includes a block of an energy-absorbing material positioned in the net for receiving loose debris produced by the explosive release of the cover plate.

  19. Gallbladder perforation by absorbable spiral tacker

    PubMed Central

    Wirsching, A; Vonlanthen, R

    2014-01-01

    Introduction Mesh fixation with tacker systems is common in laparoscopic and open hernia repair. Complications due to absorbable tackers are rare and have not been described in the literature. However, we report a case of gallbladder erosion due to tacker dislocation. Methods An open hernia repair was performed using an intraperitoneal onlay mesh for a recurrent parastomal hernia after two previous mesh repairs in a 67-year-old patient. Results On postoperative day 2, the patient was reoperated because of a dislocated tacker that eroded and perforated the fundus region of the gallbladder. Putatively, tacker dislocation occurred owing to imbalanced traction forces. Initially, the mesh was fixed with absorbable tackers around the stoma on the right and transmuscular suture fixation was carried out on the left abdominal side. On revision surgery, tension forces to the right were therefore neutralised by additional transmuscular sutures on the right side. Conclusions Absorbable tackers in open hernia repair provide a safe and effective mesh fixation if tension forces are carefully avoided. PMID:25245719

  20. Development of monofilar rotor hub vibration absorber

    NASA Technical Reports Server (NTRS)

    Duh, J.; Miao, W.

    1983-01-01

    A design and ground test program was conducted to study the performance of the monofilar absorber for vibration reduction on a four-bladed helicopter. A monofilar is a centrifugal tuned two degree-of-freedom rotor hub absorber that provides force attenuation at two frequencies using the same dynamic mass. Linear and non-linear analyses of the coupled monofilar/airframe system were developed to study tuning and attenuation characteristics. Based on the analysis, a design was fabricated and impact bench tests verified the calculated non-rotating natural frequencies and mode shapes. Performance characteristics were measured using a rotating absorber test facility. These tests showed significant attenuation of fixed-system 4P hub motions due to 3P inplane rotating-system hub forces. In addition, detuning effects of the 3P monofilar modal response were small due to the nonlinearities and tuning pin slippage. However, attenuation of 4P hub motions due to 5P inplane hub forces was poor. The performance of the 5P monofilar modal response was degraded by torsional motion of the dynamic mass relative to the support arm which resulted in binding of the dynamic components. Analytical design studies were performed to evaluate this torsional motion problem. An alternative design is proposed which may alleviate the torsional motion of the dynamic mass.

  1. Timing the warm absorber in NGC4051

    NASA Astrophysics Data System (ADS)

    Silva, C.; Uttley, P.; Costantini, E.

    2015-07-01

    In this work we have combined spectral and timing analysis in the characterization of highly ionized outflows in Seyfert galaxies, the so-called warm absorbers. Here, we present our results on the extensive ˜600ks of XMM-Newton archival observations of the bright and highly variable Seyfert 1 galaxy NGC4051, whose spectrum has revealed a complex multi-component wind. Working simultaneously with RGS and PN data, we have performed a detailed analysis using a time-dependent photoionization code in combination with spectral and Fourier timing techniques. This method allows us to study in detail the response of the gas due to variations in the ionizing flux of the central source. As a result, we will show the contribution of the recombining gas to the time delays of the most highly absorbed energy bands relative to the continuum (Silva, Uttley & Costantini in prep.), which is also vital information for interpreting the continuum lags associated with propagation and reverberation effects in the inner emitting regions. Furthermore, we will illustrate how this powerful method can be applied to other sources and warm-absorber configurations, allowing for a wide range of studies.

  2. Garlic for the common cold.

    PubMed

    Lissiman, Elizabeth; Bhasale, Alice L; Cohen, Marc

    2014-11-11

    Background Garlic is alleged to have antimicrobial and antiviral properties that relieve the common cold, among other beneficial effects. There is widespread usage of garlic supplements. The common cold is associated with significant morbidity and economic consequences. On average, children have six to eight colds per year and adults have two to four.Objectives To determine whether garlic (Allium sativum) is effective for the prevention or treatment of the common cold, when compared to placebo, no treatment or other treatments.Search methods We searched CENTRAL (2014, Issue 7),OLDMEDLINE (1950 to 1965),MEDLINE (January 1966 to July week 5, 2014), EMBASE(1974 to August 2014) and AMED (1985 to August 2014).Selection criteria Randomised controlled trials of common cold prevention and treatment comparing garlic with placebo, no treatment or standard treatment.Data collection and analysis Two review authors independently reviewed and selected trials from searches, assessed and rated study quality and extracted relevant data.Main results In this updated review, we identified eight trials as potentially relevant from our searches. Again, only one trial met the inclusion criteria.This trial randomly assigned 146 participants to either a garlic supplement (with 180 mg of allicin content) or a placebo (once daily)for 12 weeks. The trial reported 24 occurrences of the common cold in the garlic intervention group compared with 65 in the placebo group (P value < 0.001), resulting in fewer days of illness in the garlic group compared with the placebo group (111 versus 366). The number of days to recovery from an occurrence of the common cold was similar in both groups (4.63 versus 5.63). Only one trial met the inclusion criteria, therefore limited conclusions can be drawn. The trial relied on self reported episodes of the common cold but was of reasonable quality in terms of randomisation and allocation concealment. Adverse effects included rash and odour. Authors' conclusions

  3. Recycling of cold-stable microtubules: evidence that cold stability is due to substoichiometric polymer blocks.

    PubMed

    Job, D; Rauch, C T; Fischer, E H; Margolis, R L

    1982-02-02

    A substantial subpopulation of mammalian brain crude extract microtubules is resistant to cold-temperature disassembly. We propose here that microtubules are rendered cold stable by rare substoichiometric blocks. Mild shearing of rat brain cold-stable microtubules makes them largely cold labile. In addition, cold-stable microtubules can be destabilized by exposure to low concentrations of calmodulin (5 microM) in the presence of calcium at 0 degree C. Cold-disassembled microtubule protein, obtained from sheared or calmodulin-treated cold-stable preparations, re-forms a cold-stable subpopulation upon reassembly. These observations allow strategies for the recycling purification of cold-stable microtubules. Comparison of purified cold-labile and cold-stable material by gel electrophoresis shows enrichment for a few unique polypeptides, of 135, 70-82, and 56 kilodaltons, in the cold-stable preparation. The 64-kilodalton "switch protein", previously identified as uniquely dephosphorylated in cold-stable microtubules, is equally represented in recycled cold-stable and cold-labile microtubule preparations. Furthermore, when disassembled, cold-stable microtubule proteins are passed through a calmodulin affinity column on which the polypeptides characteristic of cold-stable microtubules are specifically retained, the breakthrough (unbound) material repolymerizes into cold-labile microtubules only. Based on the above data, a model is presented in which microtubules are rendered cold stable by the presence of substoichiometric, calmodulin-sensitive blocks that randomly reshuffle upon reassembly of cold-stable microtubules.

  4. Primary (idiopathic) cold urticaria and cholinergic urticaria.

    PubMed

    Kim, Gene

    2004-11-30

    A 76-year-old man with a longstanding history of cold sensitivity developed wheals after the application of an ice cube. Cold urticaria is a type of physical urticaria that is characterized urticaria and angioedema after exposure to cold. It may be idiopathic or secondary to hematologic or infectious diseases. Treatment of primary cold urticaria includes antihistamines; however, ketotifen, doxantrazole, zafirlukast, cyclosporine, and cold-tolerance induction may be tried in refractory cases.

  5. Modeling the Effect of Polychromatic Light in Quantitative Absorbance Spectroscopy

    ERIC Educational Resources Information Center

    Smith, Rachel; Cantrell, Kevin

    2007-01-01

    Laboratory experiment is conducted to give the students practical experience with the principles of electronic absorbance spectroscopy. This straightforward approach creates a powerful tool for exploring many of the aspects of quantitative absorbance spectroscopy.

  6. Spectrophotometry of Thin Films of Light-Absorbing Particles.

    PubMed

    Binks, Bernard P; Fletcher, Paul D I; Johnson, Andrew J; Marinopoulos, Ioannis; Crowther, Jonathan M; Thompson, Michael A

    2017-04-06

    Thin films of dispersions of light-absorbing solid particles or emulsions containing a light-absorbing solute all have a nonuniform distribution of light-absorbing species throughout the sample volume. This results in nonuniform light absorption over the illuminated area, which causes the optical absorbance, as measured using a conventional specular UV-vis spectrophotometer, to deviate from the Beer-Lambert relationship. We have developed a theoretical model to account for the absorbance properties of such films, which are shown to depend on the size and volume fraction of the light-absorbing particles plus other sample variables. We have compared model predictions with measured spectra for samples consisting of emulsions containing a dissolved light-absorbing solute. Using no adjustable parameters, the model successfully predicts the behavior of nonuniform, light-absorbing emulsion films with varying values of droplet size, volume fraction, and other parameters.

  7. Effect of inclusions' distribution on microwave absorbing properties of composites

    NASA Astrophysics Data System (ADS)

    Qin, Siliang; Wang, Qingguo; Qu, Zhaoming

    2013-03-01

    Effect of inclusions' spatial distributions on the permeability and permittivity of composites is studied using the generalized Maxwell-Garnett equations. The result indicates that inclusions' orientation distribution can increase the longitudinal electromagnetic parameters. For inclusions' random and orientation distribution, single and three-layer absorbers are designed and optimized using genetic algorithm. The result shows that under a given absorbing requirement, absorber with inclusions' orientation distribution is lighter and thinner than absorber with inclusions' random distribution.

  8. Method for absorbing an ion from a fluid

    DOEpatents

    Gao, Huizhen; Wang, Yifeng; Bryan, Charles R.

    2007-07-03

    A method for absorbing an ion from a fluid by using dispersing an organic acid into an anion surfactant solution, mixing in a divalent-metal containing compound and a trivalent-metal containing compound and calcining the resulting solid layered double hydroxide product to form an absorbent material and then contacting the absorbent material with an aqueous solution of cations or anions to be absorbed.

  9. Dynamic testing of airplane shock-absorbing struts

    NASA Technical Reports Server (NTRS)

    Langer, P; Thome, W

    1932-01-01

    Measurement of perpendicular impacts of a landing gear with different shock-absorbing struts against the drum testing stand. Tests were made with pneumatic shock absorbers having various degrees of damping, liquid shock absorbers, steel-spring shock absorbers and rigid struts. Falling tests and rolling tests. Maximum impact and gradual reduction of the impacts in number and time in the falling tests. Maximum impact and number of weaker impacts in rolling tests.

  10. An Energy Absorber for the International Space Station

    NASA Technical Reports Server (NTRS)

    Wilkes, Bob; Laurence, Lora

    2000-01-01

    The energy absorber described herein is similar in size and shape to an automotive shock absorber, requiring a constant, high load to compress over the stroke, and self-resetting with a small load. The differences in these loads over the stroke represent the energy absorbed by the device, which is dissipated as friction. This paper describes the evolution of the energy absorber, presents the results of testing performed, and shows the sensitivity of this device to several key design variables.

  11. Mathematical modeling of cold cap

    SciTech Connect

    Pokorny, Richard; Hrma, Pavel R.

    2012-10-13

    The ultimate goal of studies of cold cap behavior in glass melters is to increase the rate of glass processing in an energy-efficient manner. Regrettably, mathematical models, which are ideal tools for assessing the responses of melters to process parameters, have not paid adequate attention to the cold cap. In this study, we consider a cold cap resting on a pool of molten glass from which it receives a steady heat flux while temperature, velocity, and extent of conversion are functions of the position along the vertical coordinate. A one-dimensional (1D) mathematical model simulates this process by solving the differential equations for mass and energy balances with appropriate boundary conditions and constitutive relationships for material properties. The sensitivity analyses on the effects of incoming heat fluxes to the cold cap through its lower and upper boundaries show that the cold cap thickness increases as the heat flux from above increases, and decreases as the total heat flux increases. We also discuss the effects of foam, originating from batch reactions and from redox reactions in molten glass and argue that models must represent the foam layer to achieve a reliable prediction of the melting rate as a function of feed properties and melter conditions.

  12. Cold air systems: Sleeping giant

    SciTech Connect

    MacCracken, C.D. )

    1994-04-01

    This article describes how cold air systems help owners increase the profits from their buildings by reducing electric costs and improving indoor air quality through lower relative humidity levels. Cold air distribution involves energy savings, cost savings, space savings, greater comfort, cleaner air, thermal storage, tighter ducting, coil redesign, lower relative humidities, retrofitting, and improved indoor air quality (IAQ). It opens a door for architects, engineers, owners, builders, environmentalists, retrofitters, designers, occupants, and manufacturers. Three things have held up cold air's usage: multiple fan-powered boxes that ate up the energy savings of primary fans. Cold air room diffusers that provided inadequate comfort. Condensation from ducts, boxes, and diffusers. Such problems have been largely eliminated through research and development by utilities and manufacturers. New cold air diffusers no longer need fan powered boxes. It has also been found that condensation is not a concern so long as the ducts are located in air conditioned space, such as drop ceilings or central risers, where relative humidity falls quickly during morning startup.

  13. Spectroscopy with cold and ultra-cold neutrons

    NASA Astrophysics Data System (ADS)

    Abele, Hartmut; Jenke, Tobias; Konrad, Gertrud

    2015-05-01

    We present two new types of spectroscopy methods for cold and ultra-cold neutrons. The first method, which uses the R×B drift effect to disperse charged particles in a uniformly curved magnetic field, allows to study neutron β-decay. We aim for a precision on the 10-4 level. The second method that we refer to as gravity resonance spectroscopy (GRS) allows to test Newton's gravity law at short distances. At the level of precision we are able to provide constraints on any possible gravity-like interaction. In particular, limits on dark energy chameleon fields are improved by several orders of magnitude.

  14. Method of operating a cold cathode-cold reservoir thyratron

    SciTech Connect

    Tauber, A.; Finnegan, R.D.; Rothwarf, F.

    1984-05-22

    A method is disclosed of operating a cold-cathode-cold-reservoir thyratron for laser/radar and other systems employing high voltage and current pulses using ZrVFe as the hydrogen thyratron material. According to the method, a hydride of ZrVFe is first formed and the hydrided material then placed in the cathode structure of the thyratron. The tube is then pumped down to its operating pressure of approximately 10/sup -3/ atmospheres, the hydrided material then acting as a ballast to maintain that partial pressure of hydrogen at room temperature.

  15. 40 CFR 65.150 - Absorbers used as control devices.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 16 2014-07-01 2014-07-01 false Absorbers used as control devices. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Closed Vent Systems, Control Devices, and Routing to a Fuel Gas System or a Process § 65.150 Absorbers used as control devices. (a) Absorber equipment and...

  16. Graphene metamaterials based tunable terahertz absorber: effective surface conductivity approach.

    PubMed

    Andryieuski, Andrei; Lavrinenko, Andrei V

    2013-04-08

    In this paper we present the efficient design of functional thin-film metamaterial devices with the effective surface conductivity approach. As an example, we demonstrate a graphene based perfect absorber. After formulating the requirements to the perfect absorber in terms of surface conductivity we investigate the properties of graphene wire medium and graphene fishnet metamaterials and demonstrate both narrowband and broadband tunable absorbers.

  17. About sound mufflers sound-absorbing panels aircraft engine

    NASA Astrophysics Data System (ADS)

    Dudarev, A. S.; Bulbovich, R. V.; Svirshchev, V. I.

    2016-10-01

    The article provides a formula for calculating the frequency of sound absorbed panel with a perforated wall. And although the sound absorbing structure is a set of resonators Helmholtz, not individual resonators should be considered in acoustic calculations, and all the perforated wall panel. The analysis, showing how the parameters affect the size and sound-absorbing structures in the absorption rate.

  18. 21 CFR 880.5300 - Medical absorbent fiber.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical absorbent fiber. 880.5300 Section 880.5300... Devices § 880.5300 Medical absorbent fiber. (a) Identification. A medical absorbent fiber is a device intended for medical purposes that is made from cotton or synthetic fiber in the shape of a ball or a...

  19. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Tires and shock absorbers. 29.475 Section... shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed to be in their static position and the shock absorbers to be in their most critical position....

  20. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Tires and shock absorbers. 29.475 Section... shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed to be in their static position and the shock absorbers to be in their most critical position....

  1. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Tires and shock absorbers. 29.475 Section... shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed to be in their static position and the shock absorbers to be in their most critical position....

  2. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 29.475 Section... shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed to be in their static position and the shock absorbers to be in their most critical position....

  3. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Tires and shock absorbers. 29.475 Section... shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed to be in their static position and the shock absorbers to be in their most critical position....

  4. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  5. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  6. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  7. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  8. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  9. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  10. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  11. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  12. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  13. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  14. 21 CFR 878.4755 - Absorbable lung biopsy plug.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Absorbable lung biopsy plug. 878.4755 Section 878...) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4755 Absorbable lung biopsy plug. (a) Identification. A preformed (polymerized) absorbable lung biopsy plug is intended to...

  15. [Absorbable coronary stents. New promising technology].

    PubMed

    Erbel, Raimund; Böse, Dirk; Haude, Michael; Kordish, Igor; Churzidze, Sofia; Malyar, Nasser; Konorza, Thomas; Sack, Stefan

    2007-06-01

    Coronary stent implantation started in Germany 20 years ago. In the beginning, the progress was very slow and accelerated 10 years later. Meanwhile, coronary stent implantation is a standard procedure in interventional cardiology. From the beginning of permanent stent implantation, research started to provide temporary stenting of coronary arteries, first with catheter-based systems, later with stent-alone technology. Stents were produced from polymers or metal. The first polymer stent implantation failed except the Igaki-Tamai stent in Japan. Newly developed absorbable polymer stents seem to be very promising, as intravascular ultrasound (IVUS) and optical coherence tomography have demonstrated. Temporary metal stents were developed based on iron and magnesium. Currently, the iron stent is tested in peripheral arteries. The absorbable magnesium stent (Biotronik, Berlin, Germany) was tested in peripheral arteries below the knee and meanwhile in the multicenter international PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting with Absorbable Metal Stents) study. The first magnesium stent implantation was performed on July 30, 2004 after extended experimental testing in Essen. The magnesium stent behaved like a bare-metal stent with low recoil of 5-7%. The stent struts were absorbed when tested with IVUS. Stent struts were not visible by fluoroscopy or computed tomography (CT) as well as magnetic resonance imaging (MRI). That means, that the magnesium stent is invisible and therefore CT and MRI can be used for imaging of interventions. Only using micro-CT the stent struts were visible. The absorption process could be demonstrated in a patient 18 days after implantation due to suspected acute coronary syndrome, which was excluded. IVUS showed a nice open lumen. Stent struts were no longer visible, but replaced by tissue indicating the previous stent location. Coronary angiography after 4 months showed an ischemia-driven target lesion

  16. [Performance of desulfurizing absorbent of roasted navajoite].

    PubMed

    Chen, Fang; Yang, Chun-ping; Gan, Hai-ming; Wu, Ting; Chen, Hai-lin; Chen, Hong; Xu, Ke-hui; Xie, Geng-xin

    2010-04-01

    An innovative flue gas desulfurization (FGD) coupling process was proposed in this study to overcome the problems in wet-type limestone/lime processes which include fouling, clogging, and difficulty of selling the by-products and the problems in traditional process for vanadium extraction from navajoite ore such as excessive consumption of sulfuric acid and emissions of pollutants. The performance of a jet bubbling reactor (JBR) at pilot-scale was evaluated using navajoite ore produced in the process of extracting vanadium pentoxide as desulfurization absorbent. Results showed that navajoite ore slurry achieved better desulfurization performance than limestone slurry. When the inlet flue gas pressure drop was 3.0 kPa, the gas flow was about 2350 m3 x h(-1) and the pH of the navajoite ore slurry was higher than 4.5, the desulfurization efficiency was stable about 90%. The SO2 removal efficiency appeared to increase along with the increasing of absorbent cycle-index. The efficiency of the second circulation was improved 3.5% compared to the first circulation. After an operating duration of 40 minutes, the leaching rate of vanadium pentoxide was about 20%, and reached 60% when the by-products were leached with 5% dilute sulfuric acid for 10 hours. The by-product from this process not only could be used to produce vanadium pentoxide which is a valuable industrial product, but also could significantly overcome the pollution problem existing in the traditional refining process of vanadium pentoxide when navajoite ore is used as the feed material. This FGD process using roasted navajoite slurry as absorbent is environmental sound and cost-effective, and shows the potential for application in the field of flue gas desulfurization as well as hydrometallurgy.

  17. Exposure testing of solar absorber surfaces

    SciTech Connect

    Moore, S.W.

    1986-01-01

    The Los Alamos National Laboratory has been involved in supporting, monitoring and conducting exposure testing of solar materials for approximately ten years. The Laboratory has provided technical monitoring of the IITRI, DSET, Lockheed, and Berry contracts and has operated the Los Alamos exposure Facility for over five years. This report will outline some of the past exposure testing, the testing still in progress, and describe some of the major findings. While this report will primarily emphasize solar absorber surfaces, some of the significant findings relative to advanced glazing will be discussed.

  18. Ultra-broadband microwave metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Ding, Fei; Cui, Yanxia; Ge, Xiaochen; Jin, Yi; He, Sailing

    2012-03-01

    A microwave ultra-broadband polarization-independent metamaterial absorber is demonstrated. It is composed of a periodic array of metal-dielectric multilayered quadrangular frustum pyramids. These pyramids possess resonant absorption modes at multi-frequencies, of which the overlapping leads to the total absorption of the incident wave over an ultra-wide spectral band. The experimental absorption at normal incidence is above 90% in the frequency range of 7.8-14.7 GHz, and the absorption is kept large when the incident angle is smaller than 60°. The experimental results agree well with the numerical simulation.

  19. Electrically tunable absorber based on nonstructured graphene

    NASA Astrophysics Data System (ADS)

    Ye, Caiyan; Zhu, Zhihong; Xu, Wei; Yuan, Xiaodong; Qin, Shiqiao

    2015-12-01

    We demonstrate numerically that a tunable absorber with absorption of 99.94% in the far infrared range can be obtained using a nonstructured graphene. The mechanism originates from a nonstructured graphene film supported on a periodical dielectric array that can show Fermi level modulation periodically and produce plasmonic resonances in the far infrared range. The nonstructured graphene can avoid the unexpected edge effects and does not influence the unique properties of graphene, which will be helpful in practice to achieve the unity absorption and facilitate the development of many related applications.

  20. An electromechanical low frequency panel sound absorber.

    PubMed

    Chang, Daoqing; Liu, Bilong; Li, Xiaodong

    2010-08-01

    The sound absorbing properties of a thin micro-perforated plate (MPP) coated with piezoelectric material with shunt damping technology is investigated. First a theoretical model is presented to predict the sound absorption coefficients of a thin plate attached with a piezoelectric patch and electrical circuits. Then the model is extended to analyze the sound absorption for a thin plate with micro perforations and piezoelectric material. Measurements are also carried out in an impedance tube and found to be in good agreements with the theoretical model. The sound absorption of the constructions can be much improved by tuning the electrical circuits.

  1. Piston-rotaxanes as molecular shock absorbers.

    PubMed

    Sevick, E M; Williams, D R M

    2010-04-20

    We describe the thermomechanical response of a new molecular system that behaves as a shock absorber. The system consists of a rodlike rotaxane connected to a piston and tethered to a surface. The response of this system is dominated by the translational entropy of the rotaxane rings and can be calculated exactly. The force laws are contrasted with those for a rigid rod and a polymer. In some cases, the rotaxanes undergo a sudden transition to a tilted state when compressed. These piston-rotaxanes provide a potential motif for the design of a new class of materials with a novel thermomechanical response.

  2. DHCAL with minimal absorber: measurements with positrons

    NASA Astrophysics Data System (ADS)

    Freund, B.; Neubüser, C.; Repond, J.; Schlereth, J.; Xia, L.; Dotti, A.; Grefe, C.; Ivantchenko, V.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Marin, J.; Puerta-Pelayo, J.; Verdugo, A.; Brianne, E.; Ebrahimi, A.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Irles, A.; Krivan, F.; Krüger, K.; Kvasnicka, J.; Lu, S.; Lutz, B.; Morgunov, V.; Provenza, A.; Reinecke, M.; Sefkow, F.; Schuwalow, S.; Tran, H. L.; Garutti, E.; Laurien, S.; Matysek, M.; Ramilli, M.; Schroeder, S.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kovalcuk, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; van Doren, B.; Wilson, G. W.; Kawagoe, K.; Hirai, H.; Sudo, Y.; Suehara, T.; Sumida, H.; Takada, S.; Tomita, T.; Yoshioka, T.; Bilokin, S.; Bonis, J.; Cornebise, P.; Pöschl, R.; Richard, F.; Thiebault, A.; Zerwas, D.; Hostachy, J.-Y.; Morin, L.; Besson, D.; Chadeeva, M.; Danilov, M.; Markin, O.; Popova, E.; Gabriel, M.; Goecke, P.; Kiesling, C.; van der Kolk, N.; Simon, F.; Szalay, M.; Corriveau, F.; Blazey, G. C.; Dyshkant, A.; Francis, K.; Zutshi, V.; Kotera, K.; Ono, H.; Takeshita, T.; Ieki, S.; Kamiya, Y.; Ootani, W.; Shibata, N.; Jeans, D.; Komamiya, S.; Nakanishi, H.

    2016-05-01

    In special tests, the active layers of the CALICE Digital Hadron Calorimeter prototype, the DHCAL, were exposed to low energy particle beams, without being interleaved by absorber plates. The thickness of each layer corresponded approximately to 0.29 radiation lengths or 0.034 nuclear interaction lengths, defined mostly by the copper and steel skins of the detector cassettes. This paper reports on measurements performed with this device in the Fermilab test beam with positrons in the energy range of 1 to 10 GeV. The measurements are compared to simulations based on GEANT4 and a standalone program to emulate the detailed response of the active elements.

  3. Absorbing boundary conditions for exterior problems

    NASA Technical Reports Server (NTRS)

    Hariharan, S. I.

    1985-01-01

    Elliptic and hyperbolic problems in unbounded regions are considered. These problems, when one wants to solve them numerically, have the difficulty of prescribing boundary conditions at infinity. Computationally, one needs a finite region in which to solve these problems. The corresponding conditions at infinity imposed on the finite distance boundaries should dictate the boundary condition at infinity and be accurate with respect to the interior numerical scheme. Such boundary conditions are commonly referred to as absorbing boundary conditions. A treatment is given of these boundary conditions for wave-like equations.

  4. Highly absorbing ARC for DUV lithography

    NASA Astrophysics Data System (ADS)

    Pavelchek, Edward K.; Meador, James D.; Guerrero, Douglas J.; Lamb, James E., III; Kache, Ajit; doCanto, Manuel; Adams, Timothy G.; Stark, David R.; Miller, Daniel A.

    1996-06-01

    The properties of a new anti-reflective coating for 248 nm lithography are described. It is formed by thermally cross-linking a spin-on organic coating, and has an absorbance greater than 12/micrometers. It is compatible with UVIIHS and APEX-E photoresists. Thin films (less than 600 angstrom over silicon substrates) are found to completely suppress standing waves, to reduce EO swing curves to less than 3%, and to offer good CD control over typical field oxide topography. The etch rate was found to be comparable to that of the APEX-E photoresist.

  5. A novel broadband waterborne acoustic absorber

    NASA Astrophysics Data System (ADS)

    Wang, Changxian; Wen, Weibin; Huang, Yixing; Chen, Mingji; Lei, Hongshuai; Fang, Daining

    2016-07-01

    In this paper, we extended the ray tracing theory in polar coordinate system, and originally proposed the Snell-Descartes law in polar coordinates. Based on these theories, a novel broadband waterborne acoustic absorber device was proposed. This device is designed with gradient-distributing materials along radius, which makes the incidence acoustic wave ray warps. The echo reduction effects of this device were investigated by finite element analysis, and the numerical results show that the reflectivity of acoustic wave for the new device is lower than that of homogenous and Alberich layers in almost all frequency 0-30 kHz at the same loss factor.

  6. COLD-SAT dynamic model

    NASA Technical Reports Server (NTRS)

    Adams, Neil S.; Bollenbacher, Gary

    1992-01-01

    This report discusses the development and underlying mathematics of a rigid-body computer model of a proposed cryogenic on-orbit liquid depot storage, acquisition, and transfer spacecraft (COLD-SAT). This model, referred to in this report as the COLD-SAT dynamic model, consists of both a trajectory model and an attitudinal model. All disturbance forces and torques expected to be significant for the actual COLD-SAT spacecraft are modeled to the required degree of accuracy. Control and experimental thrusters are modeled, as well as fluid slosh. The model also computes microgravity disturbance accelerations at any specified point in the spacecraft. The model was developed by using the Boeing EASY5 dynamic analysis package and will run on Apollo, Cray, and other computing platforms.

  7. Nanofriction in cold ion traps.

    PubMed

    Benassi, A; Vanossi, A; Tosatti, E

    2011-01-01

    Sliding friction between crystal lattices and the physics of cold ion traps are so far non-overlapping fields. Two sliding lattices may either stick and show static friction or slip with dynamic friction; cold ions are known to form static chains, helices or clusters, depending on the trapping conditions. Here we show, based on simulations, that much could be learnt about friction by sliding, through, for example, an electric field, the trapped ion chains over a corrugated potential. Unlike infinite chains, in which the theoretically predicted Aubry transition to free sliding may take place, trapped chains are always pinned. Yet, a properly defined static friction still vanishes Aubry-like at a symmetric-asymmetric structural transition, found for decreasing corrugation in both straight and zig-zag trapped chains. Dynamic friction is also accessible in ringdown oscillations of the ion trap. Long theorized static and dynamic one-dimensional friction phenomena could thus become accessible in future cold ion tribology.

  8. Optical Response of Strained- and Unstrained-Silicon Cold-Electron Bolometers

    NASA Astrophysics Data System (ADS)

    Brien, T. L. R.; Ade, P. A. R.; Barry, P. S.; Dunscombe, C. J.; Leadley, D. R.; Morozov, D. V.; Myronov, M.; Parker, E. H. C.; Prest, M. J.; Prunnila, M.; Sudiwala, R. V.; Whall, T. E.; Mauskopf, P. D.

    2016-07-01

    We describe the optical characterisation of two silicon cold-electron bolometers each consisting of a small (32 × 14 mathrm {\\upmu m}) island of degenerately doped silicon with superconducting aluminium contacts. Radiation is coupled into the silicon absorber with a twin-slot antenna designed to couple to 160-GHz radiation through a silicon lens. The first device has a highly doped silicon absorber, the second has a highly doped strained-silicon absorber. Using a novel method of cross-correlating the outputs from two parallel amplifiers, we measure noise-equivalent powers of 3.0 × 10^{-16} and 6.6 × 10^{-17} mathrm {W Hz^{{-1}/{2}}} for the control and strained device, respectively, when observing radiation from a 77-K source. In the case of the strained device, the noise-equivalent power is limited by the photon noise.

  9. Insight into the Nonlinear Absorbance of Two Related Series of Two-Photon Absorbing Chromophores (Postprint)

    DTIC Science & Technology

    2007-01-01

    Reinhardt, B. A. Opt. Lett. 1995, 20, 1524. (f) Larson, E . J.; Friesen , L. A.; Johnson, C. K. Chem. Phys. Lett. 1997, 265, 161. (g) Albota, M.; Beljonne, D...62102F 5d. PROJECT NUMBER 4348 5e. TASK NUMBER RG 6. AUTHOR(S) Joy E . Rogers (UES, Inc.) Jonathan E . Slagle (AT&T Government Solutions) Daniel G...Insight into the Nonlinear Absorbance of Two Related Series of Two-Photon Absorbing Chromophores Joy E . Rogers,*,†,‡ Jonathan E . Slagle,†,§ Daniel G

  10. Magnetohydrodynamic Simulations of the Formation of Molecular Clouds toward the Stellar Cluster Westerlund 2: Interaction of a Jet with a Clumpy Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Asahina, Yuta; Kawashima, Tomohisa; Furukawa, Naoko; Enokiya, Rei; Yamamoto, Hiroaki; Fukui, Yasuo; Matsumoto, Ryoji

    2017-02-01

    The formation mechanism of CO clouds observed with the NANTEN2 and Mopra telescopes toward the stellar cluster Westerlund 2 is studied by 3D magnetohydrodynamic simulations, taking into account the interstellar cooling. These molecular clouds show a peculiar shape composed of an arc-shaped cloud on one side of the TeV γ-ray source HESS J1023-575 and a linear distribution of clouds (jet clouds) on the other side. We propose that these clouds are formed by the interaction of a jet with clumps of interstellar neutral hydrogen (H i). By studying the dependence of the shape of dense cold clouds formed by shock compression and cooling on the filling factor of H i clumps, we found that the density distribution of H i clumps determines the shape of molecular clouds formed by the jet–cloud interaction: arc clouds are formed when the filling factor is large. On the other hand, when the filling factor is small, molecular clouds align with the jet. The jet propagates faster in models with small filling factors.

  11. Voltage-dependent absorbance change of carotenoids in halophilic archaebacteria.

    PubMed

    Seki, S I; Sasabe, H; Tomioka, H

    1996-10-02

    Membrane vesicles of wild-type Halobacterium sp. mex strain show a wavy absorbance change which has not been so far reported in halophilic archaebacteria. A white mutant strain lacking carotenoids did not show the wavy absorbance change. The wavy absorbance change in the range of 440-590 nm was induced by a red flash (600-640 nm), which photoexcited electrogenic ion pumps, mex bacteriorhodopsin and mex halorhodopsin but not carotenoids. The wavy change was also caused by K+ diffusion potentials without light. These results suggest that the wavy absorbance change in the membrane vesicles is the voltage-dependent absorbance change of the carotenoids.

  12. Mapping liquid distribution in absorbent incontinence products.

    PubMed

    Landeryou, M A; Yerworth, R J; Cottenden, A M

    2003-01-01

    This paper reviews methods available for mapping the distribution of fluid in incontinence pad materials to assist with evaluating existing products and developing new ones, and to provide data for building and validating predictive models. Specifically, the following technologies are considered and their strengths and limitations described: discrete sensors based on conductance, temperature or optical measurements, optical imaging, gravimetric methods, X-ray imaging and magnetic resonance imaging. It is suggested that the ideal method would enable fluid distribution to be mapped in three dimensions with good spatial and time resolution in single materials and composite structures of simple and complex geometries under static and dynamic mechanical loading. It would also allow liquid to be mapped in products when worn by users. It is concluded that, although each existing method meets some of these requirements, and each requirement is met, at least reasonably well, by at least one method, improved techniques are needed. The particular need for methods that can provide some measurement of liquid saturation within absorbent products, both in the laboratory and in real use, is highlighted. In many cases, simple methods used appropriately are sufficient to elicit the important aspects of liquid transport and storage within absorbent products.

  13. Configurable metamaterial absorber with pseudo wideband spectrum.

    PubMed

    Zhu, Weiren; Huang, Yongjun; Rukhlenko, Ivan D; Wen, Guangjun; Premaratne, Malin

    2012-03-12

    Metamaterials attain their behavior due to resonant interactions among their subwavelength components and thus show specific designer features only in a very narrow frequency band. There is no simple way to dynamically increase the operating bandwidth of a narrowband metamaterial, but it may be possible to change its central frequency, shifting the spectral response to a new frequency range. In this paper, we propose and experimentally demonstrate a metamaterial absorber that can shift its central operating frequency by using mechanical means. The shift is achieved by varying the gap between the metamaterial and an auxiliary dielectric slab parallel to its surface. We also show that it is possible to create multiple absorption peaks by adjusting the size and/or shape of the dielectric slab, and to shift them by moving the slab relative to the metamaterial. Specifically, using numerical simulations we design a microwave metamaterial absorber and experimentally demonstrate that its central frequency can be set anywhere in a 1.6 GHz frequency range. The proposed configuration is simple and easy to make, and may be readily extended to THz frequencies.

  14. Wave based optimization of distributed vibration absorbers

    NASA Astrophysics Data System (ADS)

    Johnson, Marty; Batton, Brad

    2005-09-01

    The concept of distributed vibration absorbers or DVAs has been investigated in recent years as a method of vibration control and sound radiation control for large flexible structures. These devices are comprised of a distributed compliant layer with a distributed mass layer. When such a device is placed onto a structure it forms a sandwich panel configuration with a very soft core. With this configuration the main effect of the DVA is to create forces normal to the surface of the structure and can be used at low frequencies to either add damping, where constrain layer damper treatments are not very effective, or to pin the structure over a narrow frequency bandwidth (i.e., large input impedance/vibration absorber approach). This paper analyses the behavior of these devices using a wave based approach and finds an optimal damping level for the control of broadband disturbances in panels. The optimal design is calculated by solving the differential equations for waves propagating in coupled plates. It is shown that the optimal damping calculated using the infinite case acts as a good ``rule of thumb'' for designing DVAs to control the vibration of finite panels. This is bourn out in both numerical simulations and experiments.

  15. Spacesuit Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Hodgson, Ed; Izenson, Mike; Chan, Weibo; Bue, Grant C.

    2012-01-01

    For decades advanced spacesuit developers have pursued a regenerable, robust nonventing system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s Lithium Chloride Absorber Radiator (LCAR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. This water vapor is then captured by solid LiCl in the LCAR with a high enthalpy of absorption, resulting in sufficient temperature lift to reject heat to space by radiation. After the sortie, the LCAR would be heated up and dried in a regenerator to drive off and recover the absorbed evaporant. A engineering development prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The LCAR was able to stably reject 75 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

  16. Possible Quantum Absorber Effects in Cortical Synchronization

    NASA Astrophysics Data System (ADS)

    Kämpf, Uwe

    The Wheeler-Feynman transactional "absorber" approach was proposed originally to account for anomalous resonance coupling between spatio-temporally distant measurement partners in entangled quantum states of so-called Einstein-Podolsky-Rosen paradoxes, e.g. of spatio-temporal non-locality, quantum teleportation, etc. Applied to quantum brain dynamics, however, this view provides an anticipative resonance coupling model for aspects of cortical synchronization and recurrent visual action control. It is proposed to consider the registered activation patterns of neuronal loops in so-called synfire chains not as a result of retarded brain communication processes, but rather as surface effects of a system of standing waves generated in the depth of visual processing. According to this view, they arise from a counterbalance between the actual input's delayed bottom-up data streams and top-down recurrent information-processing of advanced anticipative signals in a Wheeler-Feynman-type absorber mode. In the framework of a "time-loop" model, findings about mirror neurons in the brain cortex are suggested to be at least partially associated with temporal rather than spatial mirror functions of visual processing, similar to phase conjugate adaptive resonance-coupling in nonlinear optics.

  17. Fabrication of THz Sensor with Metamaterial Absorber

    NASA Astrophysics Data System (ADS)

    Gonzalez, Hugo; Alves, Fabio; Karunasiri, Gamani

    The terahertz (THz) portion of the electromagnetic spectrum (0.1-10 THz) has not been fully utilized due to the lack of sensitive detectors. Real-time imaging in this spectral range has been demonstrated using uncooled infrared microbolometer cameras and external illumination provided by quantum cascade laser (QCL) based THz sources. However, the microbolometer pixels in the cameras have not been optimized to achieve high sensitivity in THz frequencies. Recently, we have developed a highly sensitive micromechanical THz sensor employing bi-material effect with an integrated metamaterial absorber tuned to the THz frequency of interest. The use of bi-material structures causes deflection on the sensor to as the absorbed THz radiation increases its temperature, which can be monitored optically by reflecting a light beam. This approach eliminates the integration of readout electronics needed in microbolometers. The absorption of THz by metamaterial can be tailored by controlling geometrical parameters. The sensors can be fabricated using conventional microelectronic materials and incorporated into pixels to form focal plane arrays (FPAs). In this presentation, characterization and readout of a THz sensor with integrated metamaterial structure will be described. Supported by DoD.

  18. Wave energy extraction by coupled resonant absorbers.

    PubMed

    Evans, D V; Porter, R

    2012-01-28

    In this article, a range of problems and theories will be introduced that will build towards a new wave energy converter (WEC) concept, with the acronym 'ROTA' standing for resonant over-topping absorber. First, classical results for wave power absorption for WECs constrained to operate in a single degree of freedom will be reviewed and the role of resonance in their operation highlighted. Emphasis will then be placed on how the introduction of further resonances can improve power take-off characteristics by extending the range of frequencies over which the efficiency is close to a theoretical maximum. Methods for doing this in different types of WECs will be demonstrated. Coupled resonant absorbers achieve this by connecting a WEC device equipped with its own resonance (determined from a hydrodynamic analysis) to a new system having separate mass/spring/damper characteristics. It is shown that a coupled resonant effect can be realized by inserting a water tank into a WEC, and this idea forms the basis of the ROTA device. In essence, the idea is to exploit the coupling between the natural sloshing frequencies of the water in the internal tank and the natural resonance of a submerged buoyant circular cylinder device that is tethered to the sea floor, allowing a rotary motion about its axis of attachment.

  19. Erbium concentration dependent absorbance in tellurite glass

    SciTech Connect

    Sazali, E. S. Rohani, M. S. Sahar, M. R. Arifin, R. Ghoshal, S. K. Hamzah, K.

    2014-09-25

    Enhancing the optical absorption cross-section in topically important rare earth doped tellurite glasses is challenging for photonic devices. Controlled synthesis and detailed characterizations of the optical properties of these glasses are important for the optimization. The influence of varying concentration of Er{sup 3+} ions on the absorbance characteristics of lead tellurite glasses synthesized via melt-quenching technique are investigated. The UV-Vis absorption spectra exhibits six prominent peaks centered at 490, 526, 652, 800, 982 and 1520 nm ascribed to the transitions in erbium ion from the ground state to the excited states {sup 4}F{sub 7/2}, {sup 2}H{sub 11/2}, {sup 4}F{sub 9/2}, {sup 4}I{sub 9/2}, {sup 2}H{sub 11/2} and {sup 4}I{sub 13/2}, respectively. The results are analyzed by means of optical band gap E{sub g} and Urbach energy E{sub u}. The values of the energy band gap are found decreased from 2.82 to 2.51 eV and the Urbach energy increased from 0.15 to 0.24 eV with the increase of the Er{sub 2}O{sub 3} concentration from 0 to 1.5 mol%. The excellent absorbance of the prepared tellurite glasses makes them suitable for fabricating solid state lasers.

  20. Avionics Box Cold Plate Damage Prevention

    NASA Technical Reports Server (NTRS)

    Stambolian, Damon B.; Larchar, Steven W.; Henderson, Gena; Tran, Donald; Barth, Tim

    2012-01-01

    Problem Introduction: 1. Prevent Cold Plate Damage in Space Shuttle. 1a. The number of cold plate problems had increased from an average of 16.5 per/year between 1990 through 2000, to an average of 39.6 per year between 2001through 2005. 1b. Each complete set of 80 cold plates cost approximately $29 million, an average of $362,500 per cold plate. 1c It takes four months to produce a single cold plate. 2. Prevent Cold Plate Damage in Future Space Vehicles.

  1. Determination of decay coefficients for combustors with acoustic absorbers

    NASA Technical Reports Server (NTRS)

    Mitchell, C. E.; Espander, W. R.; Baer, M. R.

    1972-01-01

    An analytical technique for the calculation of linear decay coefficients in combustors with acoustic absorbers is presented. Tuned circumferential slot acoustic absorbers were designed for the first three transverse modes of oscillation, and decay coefficients for these absorbers were found as a function of backing distance for seven different chamber configurations. The effectiveness of the absorbers for off-design values of the combustion response and acoustic mode is also investigated. Results indicate that for tuned absorbers the decay coefficient increases approximately as the cube of the backing distance. For most off-design situations the absorber still provides a damping effect. However, if an absorber designed for some higher mode of oscillation is used to damp lower mode oscillations, a driving effect is frequently found.

  2. Container and method for absorbing and reducing hydrogen concentration

    DOEpatents

    Wicks, George G.; Lee, Myung W.; Heung, Leung K.

    2001-01-01

    A method for absorbing hydrogen from an enclosed environment comprising providing a vessel; providing a hydrogen storage composition in communication with a vessel, the hydrogen storage composition further comprising a matrix defining a pore size which permits the passage of hydrogen gas while blocking the passage of gaseous poisons; placing a material within the vessel, the material evolving hydrogen gas; sealing the vessel; and absorbing the hydrogen gas released into the vessel by the hydrogen storage composition. A container for absorbing evolved hydrogen gas comprising: a vessel having an interior and adapted for receiving materials which release hydrogen gas; a hydrogen absorbing composition in communication with the interior, the composition defining a matrix surrounding a hydrogen absorber, the matrix permitting the passage of hydrogen gas while excluding gaseous poisons; wherein, when the vessel is sealed, hydrogen gas, which is released into the vessel interior, is absorbed by the hydrogen absorbing composition.

  3. Composite neutron absorbing coatings for nuclear criticality control

    DOEpatents

    Wright, Richard N.; Swank, W. David; Mizia, Ronald E.

    2005-07-19

    Thermal neutron absorbing composite coating materials and methods of applying such coating materials to spent nuclear fuel storage systems are provided. A composite neutron absorbing coating applied to a substrate surface includes a neutron absorbing layer overlying at least a portion of the substrate surface, and a corrosion resistant top coat layer overlying at least a portion of the neutron absorbing layer. An optional bond coat layer can be formed on the substrate surface prior to forming the neutron absorbing layer. The neutron absorbing layer can include a neutron absorbing material, such as gadolinium oxide or gadolinium phosphate, dispersed in a metal alloy matrix. The coating layers may be formed by a plasma spray process or a high velocity oxygen fuel process.

  4. A shock absorber model for structure-borne noise analyses

    NASA Astrophysics Data System (ADS)

    Benaziz, Marouane; Nacivet, Samuel; Thouverez, Fabrice

    2015-08-01

    Shock absorbers are often responsible for undesirable structure-borne noise in cars. The early numerical prediction of this noise in the automobile development process can save time and money and yet remains a challenge for industry. In this paper, a new approach to predicting shock absorber structure-borne noise is proposed; it consists in modelling the shock absorber and including the main nonlinear phenomena responsible for discontinuities in the response. The model set forth herein features: compressible fluid behaviour, nonlinear flow rate-pressure relations, valve mechanical equations and rubber mounts. The piston, base valve and complete shock absorber model are compared with experimental results. Sensitivity of the shock absorber response is evaluated and the most important parameters are classified. The response envelope is also computed. This shock absorber model is able to accurately reproduce local nonlinear phenomena and improves our state of knowledge on potential noise sources within the shock absorber.

  5. Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint

    SciTech Connect

    Stynes, J. K.; Ihas, B.

    2012-04-01

    As we pursue efforts to lower the capital and installation costs of parabolic trough solar collectors, it is essential to maintain high optical performance. While there are many optical tools available to measure the reflector slope errors of parabolic trough solar collectors, there are few tools to measure the absorber alignment. A new method is presented here to measure the absorber alignment in two dimensions to within 0.5 cm. The absorber alignment is measured using a digital camera and four photogrammetric targets. Physical contact with the receiver absorber or glass is not necessary. The alignment of the absorber is measured along its full length so that sagging of the absorber can be quantified with this technique. The resulting absorber alignment measurement provides critical information required to accurately determine the intercept factor of a collector.

  6. Method of absorbing UF.sub.6 from gaseous mixtures in alkamine absorbents

    DOEpatents

    Lafferty, Robert H.; Smiley, Seymour H.; Radimer, Kenneth J.

    1976-04-06

    A method of recovering uranium hexafluoride from gaseous mixtures employing as an absorbent a liquid composition at least one of the components of which is chosen from the group consisting of ethanolamine, diethanolamine, and 3-methyl-3-amino-propane-diol-1,2.

  7. "Stone Cold": Worthy of Study?

    ERIC Educational Resources Information Center

    Douthwaite, Alison

    2015-01-01

    This article draws on my experiences of teaching "Stone Cold" to respond to a blog post suggesting that the novel holds little educational value. I argue that the novel's narrative style helps to foster criticality while its subject matter can help students see the relevance of literature to the world around them. Relating this to…

  8. Underwater cold tap machine tested

    SciTech Connect

    Not Available

    1985-05-01

    Tests are complete on a strategic cold tap machine for underwater lines. The system was designed around Total's Norway-UK Frigg gas line. It provides a permanent, easily mobilized, mechanical insurance against damage to the Frigg line but also provides a proven, workable principle for the repair or modification of other lines. The design of the system is discussed.

  9. Cold fusion; Myth versus reality

    SciTech Connect

    Rabinowitz, M. )

    1990-01-01

    Experiments indicate that several different nuclear reactions are taking place. Some of the experiments point to D-D fusion with a cominant tritium channel as one of the reactions. The article notes a similarity between Prometheus and the discoveries of cold fusion.

  10. Cold plasma decontamination of foods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cold plasma is a novel nonthermal food processing technology which uses energetic, reactive gases to inactivate contaminating microbes on meats, poultry and fruits and vegetables. This flexible sanitizing method uses electricity and a carrier gas such as air, oxygen, nitrogen or helium; antimicrobi...

  11. Advances in cold plasma technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Foodborne pathogens continue to be an issue on a variety of commodities, prompting research into novel interventions. Cold plasma is a nonthermal food processing technology which uses energetic, reactive gases to inactivate contaminating microbes on meats, poultry and fruits and vegetables. The prim...

  12. The Cold Blooded Killer: Hypothermia.

    ERIC Educational Resources Information Center

    Keller, Rosanne

    Part of a series of home literacy readers with conversational text and sketches, this booklet depicts the subarctic Alaskan environment where cold makes extreme demands on body metabolism. Body temperature must be maintained above 80F (26.7C). A condition of too little body-heat is termed hypo- ('deficit') thermia ('heat'). Hypothermia is the…

  13. EDITORIAL: Cold Quantum GasesEditorial: Cold Quantum Gases

    NASA Astrophysics Data System (ADS)

    Vassen, W.; Hemmerich, A.; Arimondo, E.

    2003-04-01

    This Special Issue of Journal of Optics B: Quantum and Semiclassical Optics brings together the contributions of various researchers working on theoretical and experimental aspects of cold quantum gases. Different aspects of atom optics, matter wave interferometry, laser manipulation of atoms and molecules, and production of very cold and degenerate gases are presented. The variety of subjects demonstrates the steadily expanding role associated with this research area. The topics discussed in this issue, extending from basic physics to applications of atom optics and of cold atomic samples, include: bulletBose--Einstein condensation bulletFermi degenerate gases bulletCharacterization and manipulation of quantum gases bulletCoherent and nonlinear cold matter wave optics bulletNew schemes for laser cooling bulletCoherent cold molecular gases bulletUltra-precise atomic clocks bulletApplications of cold quantum gases to metrology and spectroscopy bulletApplications of cold quantum gases to quantum computing bulletNanoprobes and nanolithography. This special issue is published in connection with the 7th International Workshop on Atom Optics and Interferometry, held in Lunteren, The Netherlands, from 28 September to 2 October 2002. This was the last in a series of Workshops organized with the support of the European Community that have greatly contributed to progress in this area. The scientific part of the Workshop was managed by A Hemmerich, W Hogervorst, W Vassen and J T M Walraven, with input from members of the International Programme Committee who are listed below. The practical aspects of the organization were ably handled by Petra de Gijsel from the Vrije Universiteit in Amsterdam. The Workshop was funded by the European Science Foundation (programme BEC2000+), the European Networks 'Cold Quantum Gases (CQG)', coordinated by E Arimondo, and 'Cold Atoms and Ultraprecise Atomic Clocks (CAUAC)', coordinated by J Henningsen, by the German Physical Society (DFG), by

  14. Cold Stress and Urinary Frequency.

    PubMed

    Ishizuka, Osamu; Imamura, Tetsuya; Nishizawa, Osamu

    2012-03-01

    There have been few studies regarding the onset of urinary sensations and frequent urination induced by sudden whole-body cooling. In this article, we review the relationship between cold stress and urinary frequency based mainly on our previous studies. A recent study showed that cold stress induces bladder overactivity in conscious rats, and these effects were mediated, at least in part, by α1A -adrenergic receptor (AR) and α1D -AR. Another study suggested that the resiniferatoxin-sensitive nerves present in the urinary bladder may also be involved in the regulation of detrusor activity associated with cold stress. The mammalian transient receptor potential (TRP) channel family consists of 28 channels subdivided into five different classes: TRPV (vanilloid), TRPC (canonical), TRPM (melastatin), TRPML (mucolipin), and TRPA (ankyrin). TRP channels function as multifunctional sensors at the cellular level. They can be activated by physical (voltage, heat, cold, mechanical stress) or chemical stimuli and binding of specific ligands. In 2002, it was reported that a nonselective cation channel, TRPM8, could be activated by both menthol and thermal stimuli (8-28 °C). We demonstrated the presence of TRPM8 in the skin from the legs and back of rats by immunofluorescence staining and that stimulation of this receptor by menthol causes urinary frequency. There have been other reports demonstrating roles of TRPM8 not related to its thermosensory function. Further studies are needed to clarify the mechanism of cold stress-induced urinary frequency, and the roles of TRPM8 in the micturition control system.

  15. The Icy Cold Heart of Pluto

    NASA Astrophysics Data System (ADS)

    Hamilton, Douglas P.

    2015-11-01

    The locations of large deposits of frozen volatiles on planetary surfaces are largely coincident with areas receiving the minimum annual influx of solar energy; familiar examples include the polar caps of Earth and Mars. For planets tilted by more than 45 degrees, however, the poles actually receive more energy than some other latitudes. Pluto, with its current obliquity of 119 degrees, has minima in its average annual insolation at +/- 27 degrees latitude, with ~1.5% more energy flux going to the equator and ~15% more to the poles. Remarkably, the fraction of annual solar energy incident on different latitudes depends only on the obliquity of the planet and not on any of its orbital parameters.Over millions of years, Pluto's obliquity varies sinusoidally from 102-126 degrees, significantly affecting the latitudinal profile of solar energy deposition. Roughly 1Myr ago, the poles received 15% more energy that today while the equator received 13% less. The energy flux to latitudes between 25-35 degrees is far more stable, remaining low over the presumably billions of years since Pluto acquired its current spin properties. Like the poles at Earth, these mid latitudes on Pluto should be favored for the long-term deposition of volatile ices. This is, indeed, the location of the bright icy heart of Pluto, Sputnik Planum.Reflected light and emitted thermal radiation from Charon increases annual insolation to one side of Pluto by of order 0.02%. Although small, the bulk of the energy is delivered at night to Pluto's cold equatorial regions. Furthermore, Charon's thermal infrared radiation is easily absorbed by icy deposits on Pluto, slowing deposition and facilitating sublimation of volatiles. We argue that the slight but persistent preference for ices to form and survive in the anti-Charon Pluto's heart.

  16. Coughs and Colds: Medicines or Home Remedies?

    MedlinePlus

    ... Issues Listen Español Text Size Email Print Share Coughs and Colds: Medicines or Home Remedies? Page Content Article Body ​Medicines Over-the-counter (OTC) cough and cold medicines can cause serious side effects ...

  17. [The skin, cold and winter sports].

    PubMed

    Claes, G; Henry, F; Letawe, C; Piérard, G E

    2001-04-01

    Winter sports are responsible for various dermatoses which could be often avoided by simple preventive procedures. Both the severity and duration of cold exposure combined with wind speed, altitude and environmental hygrometric value govern the potential types of cold injuries.

  18. Helium Find Thaws the Cold Fusion Trail.

    ERIC Educational Resources Information Center

    Pennisi, E.

    1991-01-01

    Reported is a study of cold fusion in which trace amounts of helium, possible evidence of an actual fusion reaction, were found. Research methodology is detailed. The controversy over the validity of experimental results with cold fusion are reviewed. (CW)

  19. Cold Medicines for Kids: What's the Risk?

    MedlinePlus

    ... or difficult breathing. There's no cure for the common cold, but you can help your child feel better ... Pediatrics; 2009:1934. Pappas DE, et al. The common cold in children: Management and prevention. http://www.uptodate. ...

  20. Zinc for Colds: The Final Word?

    MedlinePlus

    ... Eby GA, et al. Reduction in duration of common colds by zinc gluconate lozenges in a double-blind ... 2014;28:4. Sexton DJ, et al. The common cold in adults: Treatment and prevention. http://www.uptodate. ...

  1. Vitamin C and the Common Cold Revisited.

    ERIC Educational Resources Information Center

    Travis, H. Richard

    1984-01-01

    Various studies indicate that Vitamin C does not prevent or cure a cold, but it may ameliorate symptoms in some individuals. The development of a balanced life-style is more effective towards cold prevention. (DF)

  2. Common cold - how to treat at home

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000466.htm Common cold - how to treat at home To use the ... Antibiotics are almost never needed to treat a common cold. Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) help lower ...

  3. Ultrathin microwave absorber based on metamaterial

    NASA Astrophysics Data System (ADS)

    Kim, Y. J.; Yoo, Y. J.; Hwang, J. S.; Lee, Y. P.

    2016-11-01

    We suggest that ultrathin broadband metamaterial is a perfect absorber in the microwave regime by utilizing the properties of a resistive sheet and metamaterial. Meta-atoms are composed of four-leaf clover-shape metallic patterns and a metal plane separated by three intermediate resistive sheet layers between four dielectric layers. We interpret the absorption mechanism of the broadband by using the distribution of surface currents at specific frequencies. The simulated absorption was over 99% in 1.8-4.2 GHz. The corresponding experimental absorption was also over 99% in 2.62-4.2 GHz; however, the absorption was slightly lower than 99% in 1.8-2.62 GHz because of the sheet resistance and the changed values for the dielectric constant. Furthermore, it is independent of incident angle. The results of this research indicate the possibility of applications, due to the suppression of noxious exposure, in cell phones, computers and microwave equipments.

  4. Electromagnetic radiation absorbers and modulators comprising polyaniline

    DOEpatents

    Epstein, Arthur J.; Ginder, John M.; Roe, Mitchell G.; Hajiseyedjavadi, Hamid

    1992-01-01

    A composition for absorbing electromagnetic radiation, wherein said electromagnetic radiation possesses a wavelength generally in the range of from about 1000 Angstroms to about 50 meters, wherein said composition comprises a polyaniline composition of the formula ##STR1## where y can be equal to or greater than zero, and R.sup.1 and R.sup.2 are independently selected from the group containing of H, --OCH.sub.3, --CH.sub.3, --F, --Cl, --Br, --I, NR.sup.3 .sub.2, --NHCOR.sup.3, --OH, --O.sup.-, SR.sup.3, --OCOR.sup.3, --NO.sub.2, --COOH, --COOR.sup.3, --COR.sup.3, --CHO, and --CN, where R.sup.3 is a C.sub.1 to C.sub.8 alkyl, aryl or aralkyl group.

  5. Cusps, self-organization, and absorbing states.

    PubMed

    Bonachela, Juan A; Alava, Mikko; Muñoz, Miguel A

    2009-05-01

    Elastic interfaces embedded in (quenched) random media exhibit metastability and stick-slip dynamics. These nontrivial dynamical features have been shown to be associated with cusp singularities of the coarse-grained disorder correlator. Here we show that annealed systems with many absorbing states and a conservation law but no quenched disorder exhibit identical cusps. On the other hand, similar nonconserved systems in the directed percolation class are also shown to exhibit cusps but of a different type. These results are obtained both by a recent method to explicitly measure disorder correlators and by defining an alternative new protocol inspired by self-organized criticality, which opens the door to easily accessible experimental realizations.

  6. Electronic and thermally tunable infrared metamaterial absorbers

    NASA Astrophysics Data System (ADS)

    Shrekenhamer, David; Miragliotta, Joseph A.; Brinkley, Matthew; Fan, Kebin; Peng, Fenglin; Montoya, John A.; Gauza, Sebastian; Wu, Shin-Tson; Padilla, Willie J.

    2016-09-01

    In this paper, we report a computational and experimental study using tunable infrared (IR) metamaterial absorbers (MMAs) to demonstrate frequency tunable (7%) and amplitude modulation (61%) designs. The dynamic tuning of each structure was achieved through the addition of an active material—liquid crystals (LC) or vanadium dioxide (VO2)-within the unit cell of the MMA architecture. In both systems, an applied stimulus (electric field or temperature) induced a dielectric change in the active material and subsequent variation in the absorption and reflection properties of the MMA in the mid- to long-wavelength region of the IR (MWIR and LWIR, respectively). These changes were observed to be reversible for both systems and dynamic in the LC-based structure.

  7. Porous Carbon Nanoparticle Networks with Tunable Absorbability

    PubMed Central

    Dai, Wei; Kim, Seong Jin; Seong, Won-Kyeong; Kim, Sang Hoon; Lee, Kwang-Ryeol; Kim, Ho-Young; Moon, Myoung-Woon

    2013-01-01

    Porous carbon materials with high specific surface areas and superhydrophobicity have attracted much research interest due to their potential application in the areas of water filtration, water/oil separation, and oil-spill cleanup. Most reported superhydrophobic porous carbon materials are fabricated by complex processes involving the use of catalysts and high temperatures but with low throughput. Here, we present a facile single-step method for fabricating porous carbon nanoparticle (CNP) networks with selective absorbability for water and oils via the glow discharge of hydrocarbon plasma without a catalyst at room temperature. Porous CNP networks were grown by the continuous deposition of CNPs at a relatively high deposition pressure. By varying the fluorine content, the porous CNP networks exhibited tunable repellence against liquids with various degrees of surface tension. These porous CNP networks could be applied for the separation of not only water/oil mixtures but also mixtures of liquids with different surface tension levels. PMID:23982181

  8. Absorbing layers for the Dirac equation

    SciTech Connect

    Pinaud, Olivier

    2015-05-15

    This work is devoted to the construction of perfectly matched layers (PML) for the Dirac equation, that not only arises in relativistic quantum mechanics but also in the dynamics of electrons in graphene or in topological insulators. While the resulting equations are stable at the continuous level, some care is necessary in order to obtain a stable scheme at the discrete level. This is related to the so-called fermion doubling problem. For this matter, we consider the numerical scheme introduced by Hammer et al. [19], and combine it with the discretized PML equations. We state some arguments for the stability of the resulting scheme, and perform simulations in two dimensions. The perfectly matched layers are shown to exhibit, in various configurations, superior absorption than the absorbing potential method and the so-called transport-like boundary conditions.

  9. Absorbed doses from temporomandibular joint radiography

    SciTech Connect

    Brooks, S.L.; Lanzetta, M.L.

    1985-06-01

    Thermoluminescent dosimeters were used in a tissue-equivalent phantom to measure doses of radiation absorbed by various structures in the head when the temporomandibular joint was examined by four different radiographic techniques--the transcranial, transorbital, and sigmoid notch (Parma) projections and the lateral tomograph. The highest doses of radiation occurred at the point of entry for the x-ray beam, ranging from 112 mrad for the transorbital view to 990 mrad for the sigmoid notch view. Only the transorbital projection a radiation dose to the lens of the eye. Of the four techniques evaluated, the lateral tomograph produced the highest doses to the pituitary gland and the bone marrow, while the sigmoid notch radiograph produced the highest doses to the parotid gland.

  10. Microcellular ceramic foams for radar absorbing structures

    SciTech Connect

    Huling, J.; Phillips, D.

    1996-09-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of this project is to develop a lightweight, semi-structural, radar-absorbing ceramic foam that can be incorporated into aircraft exhaust systems to replace many of the currently used dense ceramic parts and thereby improve the radar cross section. Although the conventional processes for producing ceramic foams have not been able to provide materials that meet the design specifications for high strength at low density, we have developed and demonstrated a novel sol-gel emulsion process for preparing microcellular ceramic foams in which compositional and microstructural control is expected to provide the requisite high-temperature radar-absorption, strength-to-weight ratio, and thermal insulative properties.

  11. The foot as a shock absorber.

    PubMed

    Salathé, E P; Arangio, G A; Salathé, E P

    1990-01-01

    A mathematical analysis of the deformation of the foot is developed to determine the role that stretch of ligaments and tendons plays in absorbing shock following impact. Our analysis is based on an anatomical biomechanical model that includes each of the bones of the foot. We calculate the time course of the deflection of the joints and the elongation of the ligaments and tendons and determine the ground reaction force acting on the heel. Quasi-linear viscoelastic theory is used for soft tissue constitutive relationships. With biomechanical data selected from the literature, we obtain a vertical force impact peak of 8000 N, occurring at 16 ms following heel strike. This is of higher magnitude and shorter duration than is found experimentally, as is to be expected, since we did not include the heel pad in our model and we assumed that the impact surface was ideally rigid.

  12. Modelling and validation of electromechanical shock absorbers

    NASA Astrophysics Data System (ADS)

    Tonoli, Andrea; Amati, Nicola; Girardello Detoni, Joaquim; Galluzzi, Renato; Gasparin, Enrico

    2013-08-01

    Electromechanical vehicle suspension systems represent a promising substitute to conventional hydraulic solutions. However, the design of electromechanical devices that are able to supply high damping forces without exceeding geometric dimension and mass constraints is a difficult task. All these challenges meet in off-road vehicle suspension systems, where the power density of the dampers is a crucial parameter. In this context, the present paper outlines a particular shock absorber configuration where a suitable electric machine and a transmission mechanism are utilised to meet off-road vehicle requirements. A dynamic model is used to represent the device. Subsequently, experimental tests are performed on an actual prototype to verify the functionality of the damper and validate the proposed model.

  13. Energy harvesting from an autoparametric vibration absorber

    NASA Astrophysics Data System (ADS)

    Yan, Zhimiao; Hajj, Muhammad R.

    2015-11-01

    The combined control and energy harvesting characteristics of an autoparametric vibration absorber consisting of a base structure subjected to the external force and a cantilever beam with a tip mass are investigated. The piezoelectric sheets are attached to the cantilever beam to convert the vibrations of the base structure into electrical energy. The coupled nonlinear representative model is developed by using the extended Hamiton’s principle. The effects of the electrical load resistance on the frequency and damping ratio of the cantilever beam are analyzed. The impacts of the external force and load resistance on the structural displacements of the base structure and the beam and on the level of harvested energy are determined. The results show that the initial conditions have a significant impact on the system’s response. The relatively high level of energy harvesting is not necessarily accompanied with the minimum displacements of the base structure.

  14. Skin interaction with absorbent hygiene products.

    PubMed

    Runeman, Bo

    2008-01-01

    Skin problems due to the use of absorbent hygiene products, such as diapers, incontinence pads, and feminine sanitary articles, are mostly due to climate or chafing discomfort. If these conditions are allowed to prevail, these may develop into an irritant contact dermatitis and eventually superficial skin infections. Skin humidity and aging skin are among the most significant predisposing and aggravating factors for dermatitis development. Improved product design features are believed to explain the decline in observed diaper dermatitis among infants. Where adult incontinence-related skin problems are concerned, it is very important to apply a holistic perspective to understand the influences due to the individual's incontinence level and skin condition, as well as the hygiene and skin care measures provided. Individuals with frail, sensitive skin or with skin diseases may preferably have to use high-quality products, equipped with superabsorbent polymers and water vapor-permeable back sheets, to minimize the risk of skin complications.

  15. Absorbable plate strength loss during molding.

    PubMed

    Ballard, Tiffany N S; Kelly, Kevin J; Zaydfudim, Victor; Walcutt, Noah L; Lahijani, Soheil S; Shack, R Bruce; Thayer, Wesley P

    2010-05-01

    Bioabsorbable plating systems play an integral role in cranial vault remodeling. After experiencing a case of plate failure requiring emergent reexploration, we investigated the potential causes. We hypothesize that extended submersion in the molding bath during plate preparation might advance the rate of hydrolysis and compromise plate structural integrity. Using an absorbable poly-D/L-lactic acid plating system, we assessed the effect of extended submersion on plate strength and stiffness when loaded in a cantilever fashion and with pure tension. We assessed these differences with the Student t test and linear regression modeling. We also generated a computer model of the plates for finite element analysis. When left in the molding bath for extended periods, the plates changed color and lost strength. After 5 minutes, 30% of maximum plate load capacity was lost in a cantilever beam test (P < 0.001) consistent with use of a 15% thinner plate. Tensile testing revealed the initial elastic modulus of 6.42 +/- 0.13 GPa decreased 16% to 5.41 +/- 0.50 GPa after 5 minutes of submersion (P = 0.027). The changes in plate strength and elastic modulus both worsened with increased submersion times. Finite element analysis of the plates also predicted clinically significant increases in plate deviation under normal loading conditions. Our study demonstrates that extended submersion of absorbable plates during molding results in a significant loss of plate strength and stiffness. Further, our computer model predicts that these changes could result in an unacceptable plate deviation under normal loading conditions. Together, these data caution against overmolding of plates to avoid compromising their structural integrity.

  16. Clearance of absorbed selenium by the liver

    SciTech Connect

    Kato, Tatsuko; Read, R.; Rozga, J.; Burk, R.F. )

    1991-03-11

    The liver plays a central role in the metabolism of selenium. It secretes plasma selenoproteins, contains a major fraction of the glutathione peroxidase in the body, and synthesizes excretory metabolites. The role of the liver in processing newly absorbed selenium was studied. Male chow-fed rats were fasted overnight and given 24 ng of selenium as {sup 75}SeO{sub 3}{sup 2{minus}} by stomach tube. Animals were exsanguinated at 15, 30, 45, 60, 90, 120, and 180 min after dosing. Comparison of {sup 75}Se uptake by liver, kidney, heart, muscle, testis, brain, and spleen indicated an earlier uptake by liver than by any other tissue. At 15 min, {sup 75}Se in the portal vein blood was 2.6 times that in the hepatic vein blood. Gel filtration analysis suggested a loose association of {sup 75}Se with protein in plasma at 15 min, but immunoprecipitation indicated it was largely in the form of selenoprotein P after 30 min. End-to-side portacaval shunts (PCS) were constructed in rats and sham-operated animals were used as controls. When {sup 75}SeO{sub 3}{sup 2{minus}} was given to animals with PCS, uptake of {sup 75}Se by liver did not precede uptake by other tissues. Also no gradient was detected across the lungs or kidney. {sup 75}Se content of the kidney was higher in PCS rats than in sham-operated rats. This is consistent with removal of the first-pass effect of the liver facilitating uptake of {sup 75}Se by systemic tissues. These results suggest that the preferential uptake of absorbed selenium by the liver is due both to its position in the portal circulation and to an intrinsic high uptake capacity.

  17. Light Absorbing Aerosols in Mexico City

    NASA Astrophysics Data System (ADS)

    Marley, N. A.; Kelley, K. L.; Kilaparty, P. S.; Gaffney, J. S.

    2008-12-01

    The direct effects of aerosol radiative forcing has been identified by the IPCC as a major uncertainty in climate modeling. The DOE Megacity Aerosol Experiment-Mexico City (MAX-Mex), as part of the MILAGRO study in March of 2006, was undertaken to reduce these uncertainties by characterization of the optical, chemical, and physical properties of atmospheric aerosols emitted from this megacity environment. Aerosol samples collected during this study using quartz filters were characterized in the uv-visible-infrared by using surface spectroscopic techniques. These included the use of an integrating sphere approach combined with the use of Kubelka-Munk theory to obtain aerosol absorption spectra. In past work black carbon has been assumed to be the only major absorbing species in atmospheric aerosols with an broad band spectral profile that follows a simple inverse wavelength dependence. Recent work has also identified a number of other absorbing species that can also add to the overall aerosol absorption. These include primary organics from biomass and trash burning and secondary organic aerosols including nitrated PAHs and humic-like substances, or HULIS. By using surface diffuse reflection spectroscopy we have also obtained spectra in the infrared that indicate significant IR absorption in the atmospheric window-region. These data will be presented and compared to spectra of model compounds that allow for evaluation of the potential importance of these species in adding strength to the direct radiative forcing of atmospheric aerosols. This work was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64327 as part of the Atmospheric Science Program.

  18. The cold equation of state of tantalum

    SciTech Connect

    Greeff, Carl W; Rudin, Sven P; Corckett, Scott D; Wills, John M

    2009-01-01

    In high-pressure isentropic compression experiments (ICE), the pressure is dominated by the cold curve. In order to obtain an accurate semi-empirical cold curve for Ta, we calculate the thermal pressure from ab initio phonon and electronic excitation spectra. The cold curve is then inferred from ultrasonic and shock data. Our empirical cold pressure is compared to density functional calculations and found to be closer to GGA results at low pressure and to approach LDA at high pressure.

  19. Sensitivity and Noise of Cold-Electron Bolometer Arrays

    NASA Astrophysics Data System (ADS)

    Mukhin, A. S.; Gordeeva, A. V.; Revin, L. S.; Abashin, A. E.; Shishov, A. A.; Pankratov, A. L.; Mahashabde, S.; Kuzmin, L. S.

    2017-01-01

    We perform experimental and theoretical studies of the series-parallel arrays of the cold-electron bolometers integrated into a cross-slot antenna and composed with an immersion silicon lens. This work is aimed at determining the efficiency of radiation absorption by bolometers, their volt-watt sensitivity, and equivalent noise power. The absorbed power was found using two independent methods, which ensured a better reliability of the results. The first method is based on comparing the experimental current-voltage characteristics of bolometers with the model based on the heat-balance equation. The second approach involves simulation of the electromagnetic properties of the system including the antenna, the lens, the bandpass filters, and the radiation source. The discrepancy among the results obtained using various methods does not exceed 30%. Optimization of the experimental setup is proposed to reach the photon-noise detection regime.

  20. Cold Tolerance of Plants Used for Cold-Regions Revegetation

    DTIC Science & Technology

    1990-10-01

    also interact among themselves. Evaporation, insolation (sunlight), soil-forming processes, soil microbiota , plant Leaf chlorosis cadfrost banding...that can etation applications. cold harden will do so with 10-14 days of exposure to Soluble carbohydrates depress freezing points and temperatures...water, melting point depression , and tissue Belding, R.D. and E. Young (1987) Shoot and root water content. Botanical Gazette, 137: 313-317. temperature

  1. Different types of cold adaptation in humans.

    PubMed

    Makinen, Tiina Maria

    2010-06-01

    Human adaptation to cold may occur through acclimatization or acclimation and includes genetic, physiologic, morphological or behavioural responses. It has been studied in indigenous populations, during polar or ski expeditions, sporting activities, military training, in urban people, or under controlled conditions involving exposures to cold air or water. Although divergent results exist between the studies, the main cold adaptation responses are either insulative (circulatory adjustments, increase of fat layer) or metabolic (shivering or nonshivering thermogenesis) and may be positive (enhanced) or negative (blunted). The pattern of cold adaptation is dependent on the type (air, water) and intensity (continuous, intermittent) of the cold exposure. In addition, several individual factors like age, sex, body composition, exercise, diet, fitness and health modify the responses to cold. Habituation of thermal sensations to cold develops first, followed by cardiovascular, metabolic and endocrinological responses. If the repeated cold stimulus is discontinued, adaptation will gradually disappear. The functional significance of physiological cold adaptation is unclear, and some of the responses can even be harmful and predispose to cold injuries. The article summarises recent research information concerning with the thermoregulatory responses related to repeated exposures to cold (air or water), and also discusses the determinants of cold adaptation, as well as its functional significance.

  2. Common Cold in Babies: Symptoms and Causes

    MedlinePlus

    Common cold in babies Symptoms and causes By Mayo Clinic Staff Symptoms The first indication of the common cold in a baby is often: A congested or ... or green Other signs and symptoms of a common cold in a baby may include: Fever Sneezing Coughing ...

  3. 77 FR 43117 - Meeting of the Cold War Advisory Committee for the Cold War Theme Study

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-23

    ... National Park Service Meeting of the Cold War Advisory Committee for the Cold War Theme Study AGENCY... with the Federal Advisory Committee Act, 5 U.S.C. Appendix, that the Cold War Advisory Committee for the Cold War Theme Study will conduct a teleconference meeting on August 3, 2012. Members of...

  4. A control strategy for adaptive absorber based on variable mass

    NASA Astrophysics Data System (ADS)

    Gao, Qiang; Han, Ning; Zhao, Yanqing; Duan, Chendong; Wang, Wanqin

    2015-07-01

    The tuned vibration absorber (TVA) has been an effective tool for vibration control. However, the application of TVA can cause resonance of the primary system and increase its vibration when the absorber is mistuned. In this paper, a novel control strategy based on adaptive tuned vibration absorber (ATVA) of variable mass is proposed to reduce the resonance of the primary system. Unlike most ATVAs suggested by other researchers which adjust the absorber natural frequency by changing the stiffness, the variable mass ATVA varies its natural frequency by changing absorber mass to match the excitation frequency. Some simulations and experiments were conducted to test the performance of the control strategy. The results show that the proposed control plan can widen the frequency bandwidth of the absorber, as well as suppress the resonance of the primary system significantly. This implies that the work is useful for practical applications of ATVA.

  5. Polarization independent broadband metamaterial absorber based on tapered helical structure

    NASA Astrophysics Data System (ADS)

    Agarwal, Sajal; Prajapati, Y. K.; Singh, V.; Saini, J. P.

    2015-12-01

    This communication presents a tapered helical structure as absorber, made of unconventional material i.e. metamaterial. Modeling, analytical study and the optimization of the absorber have been done. Quad helical optimized structure gives almost unity absorption at 499 nm wavelength and gives the absorption more than 75% from 300 nm to 1650 nm which is a very wide operating region with, average absorbance of 91.32%. Whereas, triple helical structure gives 85% average absorbance with the operating range from 300 nm to 1350 nm. Also, it is analyzed that the presented structures are polarization independent and broadband. Comparison of the proposed quad helical absorber with the existing metamaterial absorbers is done and found it is most eligible.

  6. Measurement and Simulation Results of Ti Coated Microwave Absorber

    SciTech Connect

    Sun, Ding; McGinnis, Dave; /Fermilab

    1998-11-01

    When microwave absorbers are put in a waveguide, a layer of resistive coating can change the distribution of the E-M fields and affect the attenuation of the signal within the microwave absorbers. In order to study such effect, microwave absorbers (TT2-111) were coated with titanium thin film. This report is a document on the coating process and measurement results. The measurement results have been used to check the simulation results from commercial software HFSS (High Frequency Structure Simulator.)

  7. Design of Tunable, Thin, and Wide-band Microwave Absorbers

    DTIC Science & Technology

    2012-04-05

    switchable or tunable radar absorbers, which are very useful in electromagnetic compatibility test facilities, radar camouflage and deception roles, and...applications requires switchable or tunable radar absorbers, which are very useful in electromagnetic compatibility test facilities, radar camouflage ...2012. [2] Q. Zhang and Z. Shen, “A dual-polarized switchable microwave absorber,” IEEE AP- S International Symposium , Chicago, July 2012.

  8. Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads

    NASA Technical Reports Server (NTRS)

    Amer, K. B.; Neff, J. R.

    1974-01-01

    The use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads was discussed. A qualitative description was given of the concept of the dynamic absorbers and some results of analytical studies showing the degree of reduction in vibratory loads attainable are presented. Operational experience of vertical plane dynamic absorbers on the OH-6A helicopter is also discussed.

  9. Cold dark matter heats up.

    PubMed

    Pontzen, Andrew; Governato, Fabio

    2014-02-13

    A principal discovery in modern cosmology is that standard model particles comprise only 5 per cent of the mass-energy budget of the Universe. In the ΛCDM paradigm, the remaining 95 per cent consists of dark energy (Λ) and cold dark matter. ΛCDM is being challenged by its apparent inability to explain the low-density 'cores' of dark matter measured at the centre of galaxies, where centrally concentrated high-density 'cusps' were predicted. But before drawing conclusions, it is necessary to include the effect of gas and stars, historically seen as passive components of galaxies. We now understand that these can inject heat energy into the cold dark matter through a coupling based on rapid gravitational potential fluctuations, explaining the observed low central densities.

  10. Ultra-cold molecule production.

    SciTech Connect

    Ramirez-Serrano, Jamie; Chandler, David W.; Strecker, Kevin; Rahn, Larry A.

    2005-12-01

    The production of Ultra-cold molecules is a goal of many laboratories through out the world. Here we are pursuing a unique technique that utilizes the kinematics of atomic and molecular collisions to achieve the goal of producing substantial numbers of sub Kelvin molecules confined in a trap. Here a trap is defined as an apparatus that spatially localizes, in a known location in the laboratory, a sample of molecules whose temperature is below one degree absolute Kelvin. Further, the storage time for the molecules must be sufficient to measure and possibly further cool the molecules. We utilize a technique unique to Sandia to form cold molecules from near mass degenerate collisions between atoms and molecules. This report describes the progress we have made using this novel technique and the further progress towards trapping molecules we have cooled.

  11. Dual band metamaterial perfect absorber based on artificial dielectric "molecules".

    PubMed

    Liu, Xiaoming; Lan, Chuwen; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-07-13

    Dual band metamaterial perfect absorbers with two absorption bands are highly desirable because of their potential application areas such as detectors, transceiver system, and spectroscopic imagers. However, most of these dual band metamaterial absorbers proposed were based on resonances of metal patterns. Here, we numerically and experimentally demonstrate a dual band metamaterial perfect absorber composed of artificial dielectric "molecules" with high symmetry. The artificial dielectric "molecule" consists of four "atoms" of two different sizes corresponding to two absorption bands with near unity absorptivity. Numerical and experimental absorptivity verify that the dual-band metamaterial absorber is polarization insensitive and can operate in wide-angle incidence.

  12. Optimal active vibration absorber: Design and experimental results

    NASA Technical Reports Server (NTRS)

    Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

    1992-01-01

    An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

  13. Acclimatization to cold in humans

    NASA Technical Reports Server (NTRS)

    Kaciuba-Uscilko, Hanna; Greenleaf, John E.

    1989-01-01

    This review focuses on the responses and mechanisms of both natural and artificial acclimatization to a cold environment in mammals, with specific reference to human beings. The purpose is to provide basic information for designers of thermal protection systems for astronauts during intra- and extravehicular activities. Hibernation, heat production, heat loss, vascular responses, body insulation, shivering thermogenesis, water immersion, exercise responses, and clinical symptoms and hypothermia in the elderly are discussed.

  14. Medical problems from cold exposure

    SciTech Connect

    Dembert, M.L.

    1982-01-01

    Problems resulting from cold exposure can be successfully treated when a coordinated emergency medical transport system and appropriate equipment are available, as well as medical personnel knowledgeable in the management of frostbite and hypothermia. Clinical suspicion of these disorders is essential. Profoundly hypothermic individuals with no recordable vital signs have been resuscitated after controlled, rapid rewarming measures and the use of emergency life-support systems.

  15. Cold cathode vacuum discharge tube

    DOEpatents

    Boettcher, Gordon E.

    1998-01-01

    A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

  16. Magnesium Repair by Cold Spray

    DTIC Science & Technology

    2008-05-01

    were conducted using microstructural analysis, hardness, bond strength, and corrosion testing. 15. SUBJECT TERMS Cold spray, magnesium, aluminum ... corrosion pitting are the primary causes for removing the components from service. In addition, any repair must be confined to nonstructural areas of...unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The U.S. Army has experienced significant corrosion problems with magnesium alloys that are used to

  17. Small Cold Temperature Instrument Packages

    NASA Astrophysics Data System (ADS)

    Clark, P. E.; Millar, P. S.; Yeh, P. S.; Feng, S.; Brigham, D.; Beaman, B.

    We are developing a small cold temperature instrument package concept that integrates a cold temperature power system with ultra low temperature ultra low power electronics components and power supplies now under development into a 'cold temperature surface operational' version of a planetary surface instrument package. We are already in the process of developing a lower power lower temperature version for an instrument of mutual interest to SMD and ESMD to support the search for volatiles (the mass spectrometer VAPoR, Volatile Analysis by Pyrolysis of Regolith) both as a stand alone instrument and as part of an environmental monitoring package. We build on our previous work to develop strategies for incorporating Ultra Low Temperature/Ultra Low Power (ULT/ULP) electronics, lower voltage power supplies, as well as innovative thermal design concepts for instrument packages. Cryotesting has indicated that our small Si RHBD CMOS chips can deliver >80% of room temperature performance at 40K (nominal minimum lunar surface temperature). We leverage collaborations, past and current, with the JPL battery development program to increase power system efficiency in extreme environments. We harness advances in MOSFET technology that provide lower voltage thresholds for power switching circuits incorporated into our low voltage power supply concept. Conventional power conversion has a lower efficiency. Our low power circuit concept based on 'synchronous rectification' could produce stable voltages as low as 0.6 V with 85% efficiency. Our distributed micro-battery-based power supply concept incorporates cold temperature power supplies operating with a 4 V or 8 V battery. This work will allow us to provide guidelines for applying the low temperature, low power system approaches generically to the widest range of surface instruments.

  18. Microscopic analysis of saturable absorbers: Semiconductor saturable absorber mirrors versus graphene

    SciTech Connect

    Hader, J.; Moloney, J. V.; Yang, H.-J.; Scheller, M.; Koch, S. W.

    2016-02-07

    Fully microscopic many-body calculations are used to study the influence of strong sub-picosecond pulses on the carrier distributions and corresponding optical response in saturable absorbers used for mode-locking—semiconductor (quantum well) saturable absorber mirrors (SESAMs) and single layer graphene based saturable absorber mirrors (GSAMs). Unlike in GSAMs, the saturation fluence and recovery time in SESAMs show a strong spectral dependence. While the saturation fluence in the SESAM is minimal at the excitonic bandgap, the optimal recovery time and least pulse distortion due to group delay dispersion are found for excitation higher in the first subband. For excitation near the SESAM bandgap, the saturation fluence is about one tenth of that in the GSAM. At energies above the bandgap, the fluences in both systems become similar. A strong dependence of the saturation fluence on the pulse width in both systems is caused by carrier relaxation during the pulse. The recovery time in graphene is found to be about two to four times faster than that in the SESAMs. The occurrence of negative differential transmission in graphene is shown to be caused by dopant related carriers. In SESAMs, a negative differential transmission is found when exciting below the excitonic resonance where excitation induced dephasing leads to an enhancement of the absorption. Comparisons of the simulation data to the experiment show a very good quantitative agreement.

  19. Cold cathode vacuum gauging system

    DOEpatents

    Denny, Edward C.

    2004-03-09

    A vacuum gauging system of the cold cathode type is provided for measuring the pressure of a plurality of separate vacuum systems, such as in a gas centrifuge cascade. Each casing is fitted with a gauge tube assembly which communicates with the vacuum system in the centrifuge casing. Each gauge tube contains an anode which may be in the form of a slender rod or wire hoop and a cathode which may be formed by the wall of the gauge tube. The tube is provided with an insulated high voltage connector to the anode which has a terminal for external connection outside the vacuum casing. The tube extends from the casing so that a portable magnet assembly may be inserted about the tube to provide a magnetic field in the area between the anode and cathode necessary for pressure measurements in a cold cathode-type vacuum gauge arrangement. The portable magnetic assembly is provided with a connector which engages the external high voltage terminal for providing power to the anode within in the gauge tube. Measurement is made in the same manner as the prior cold cathode gauges in that the current through the anode to the cathode is measured as an indication of the pressure. By providing the portable magnetic assembly, a considerable savings in cost, installation, and maintenance of vacuum gauges for pressure measurement in a gas centrifuge cascade is realizable.

  20. Mars: Always Cold, Sometimes Wet?

    NASA Technical Reports Server (NTRS)

    Lee, Pascal; McKay, Christoper P.

    2003-01-01

    A synthesis of a diverse suite of observations of H2O-related landforms that are possible Mars analogs from terrestrial polar regions (Devon Island in the Arctic; the Dry Valleys of Antarctica) put into question any requirement for extended episode(s) of warm and wet climate in Mars past. Geologically transient episodes of localized H2O cycling, forced by exogenic impacts, enhanced endogenic heat flow, and/or orbit-driven short-term local environmental change under an otherwise cold, low pressure (=10(exp 2) mbar) global climate, may be sufficient to account for the martian surface's exposed record of aqueous activity. A Mars that was only sometimes locally warm and wet while remaining climatically cold throughout its history is consistent with results (difficulties) encountered in modeling efforts attempting to support warm martian climate hypotheses. Possible analogs from terrestrial cold climate regions for the recent gully features on Mars also illustrate how transient localized aqueous activity might, under specific circumstances, also occur on Mars under the present frigid global climatic regime.

  1. Cold Ion Escape from Mars

    NASA Astrophysics Data System (ADS)

    Fränz, M.; Dubinin, E.; Wei, Y.; Morgan, D.; Andrews, D.; Barabash, S.; Lundin, R.; Fedorov, A.

    2013-09-01

    It has always been challenging to observe the flux of ions with energies of less than 10eV escaping from the planetary ionospheres. We here report on new measurements of the ionospheric ion flows at Mars by the ASPERA-3 experiment on board Mars Express in combination with the MARSIS radar experiment. We first compare calculations of the mean ion flux observed by ASPERA-3 alone with previously published results. We then combine observations of the cold ion velocity by ASPERA-3 with observations of the cold plasma density by MARSIS since ASPERA-3 misses the cold core of the ion distribution. We show that the mean density of the nightside plasma observed by MARSIS is about two orders higher than observed by ASPERA-3 (Fig.1). Combining both datasets we show that the main escape channel is along the shadow boundary on the tailside of Mars (Fig. 2). At a distance of about 0.5 R_M the flux settles at a constant value (Fig. 3) which indicates that about half of the transterminator ionospheric flow escapes from the planet. Possible mechanism to generate this flux can be the ionospheric pressure gradient between dayside and nightside or momentum transfer from the solar wind via the induced magnetic field since the flow velocity is in the Alfvénic regime.

  2. Micro-Kelvin cold molecules.

    SciTech Connect

    Strecker, Kevin E.; Chandler, David W.

    2009-10-01

    We have developed a novel experimental technique for direct production of cold molecules using a combination of techniques from atomic optical and molecular physics and physical chemistry. The ability to produce samples of cold molecules has application in a broad spectrum of technical fields high-resolution spectroscopy, remote sensing, quantum computing, materials simulation, and understanding fundamental chemical dynamics. Researchers around the world are currently exploring many techniques for producing samples of cold molecules, but to-date these attempts have offered only limited success achieving milli-Kelvin temperatures with low densities. This Laboratory Directed Research and Development project is to develops a new experimental technique for producing micro-Kelvin temperature molecules via collisions with laser cooled samples of trapped atoms. The technique relies on near mass degenerate collisions between the molecule of interest and a laser cooled (micro-Kelvin) atom. A subset of collisions will transfer all (nearly all) of the kinetic energy from the 'hot' molecule, cooling the molecule at the expense of heating the atom. Further collisions with the remaining laser cooled atoms will thermally equilibrate the molecules to the micro-Kelvin temperature of the laser-cooled atoms.

  3. Physiological characteristics of cold acclimatization in man

    NASA Astrophysics Data System (ADS)

    Mathew, Lazar; Purkayastha, S. S.; Jayashankar, A.; Nayar, H. S.

    1981-09-01

    Studies were conducted on 15 healthy young soldiers to evaluate the effect of a cold acclimatization schedule on the thermoregulatory and metabolic activity on exposure to acute cold stress. These men were exposed to cold (10‡C) for 4 h daily wearing only shorts for 21 days, in a cold chamber. They were subjected to a standard cold test at 10 ± 1‡C the day 1, 6, 11 and 21. The subjects were made to relax in a thermoneutral room (26 28‡C) for 1 h and their heart rate, blood pressure, oxygen consumption, oral temperature, mean skin temperature, mean body temperature, peripheral temperatures, and shivering activity were recorded. Then they were exposed to 10‡C and measurements were repeated at 30 min intervals, for 2 h. The cold induced vasodilatation (CIVD), cold pressor response and thermoregulatory efficiency tests were measured initially and at the end of acclimatization schedule. The data show that the procedure resulted in elevated resting metabolism, less fall in body temperature during acute cold stress, reduction in shivering, improvement in CIVD and thermoregulatory efficiency and less rise in BP and HR during cold pressor response. The data suggest the possibility of cold acclimatization in man by repeated exposure to moderately severe cold stress.

  4. Clumpy dust clouds and extended atmosphere of the AGB star W Hydrae revealed with VLT/SPHERE-ZIMPOL and VLTI/AMBER. II. Time variations between pre-maximum and minimum light

    NASA Astrophysics Data System (ADS)

    Ohnaka, K.; Weigelt, G.; Hofmann, K.-H.

    2017-01-01

    Aims: Our recent visible polarimetric images of the well-studied AGB star W Hya taken at pre-maximum light (phase 0.92) with VLT/SPHERE-ZIMPOL have revealed clumpy dust clouds close to the star at 2 R⋆. We present second-epoch SPHERE-ZIMPOL observations of W Hya at minimum light (phase 0.54) as well as high-spectral resolution long-baseline interferometric observations with the AMBER instrument at the Very Large Telescope Interferometer (VLTI). Methods: We observed W Hya with VLT/SPHERE-ZIMPOL at three wavelengths in the continuum (645, 748, and 820 nm), in the Hα line at 656.3 nm, and in the TiO band at 717 nm. The VLTI/AMBER observations were carried out in the wavelength region of the CO first overtone lines near 2.3 μm with a spectral resolution of 12 000. Results: The high-spatial resolution polarimetric images obtained with SPHERE-ZIMPOL have allowed us to detect clear time variations in the clumpy dust clouds as close as 34-50 mas (1.4-2.0 R⋆) to the star. We detected the formation of a new dust cloud as well as the disappearance of one of the dust clouds detected at the first epoch. The Hα and TiO emission extends to 150 mas ( 6 R⋆), and the Hα images obtained at two epochs reveal time variations. The degree of linear polarization measured at minimum light, which ranges from 13 to 18%, is higher than that observed at pre-maximum light. The power-law-type limb-darkened disk fit to the AMBER data in the continuum results in a limb-darkened disk diameter of 49.1 ± 1.5 mas and a limb-darkening parameter of 1.16 ± 0.49, indicating that the atmosphere is more extended with weaker limb-darkening compared to pre-maximum light. Our Monte Carlo radiative transfer modeling shows that the second-epoch SPHERE-ZIMPOL data can be explained by a shell of 0.1 μm grains of Al2O3, Mg2SiO4, and MgSiO3 with a 550 nm optical depth of 0.6 ± 0.2 and an inner and outer radii of 1.3 R⋆ and 10 ± 2R⋆, respectively. Our modeling suggests the predominance of small (0

  5. Cold Pools in the Columbia Basin

    SciTech Connect

    Whiteman, Charles D.; Zhong, Shiyuan; Shaw, William J.; Hubbe, John M.; Bian, Xindi; Mittelstadt, J.

    2001-01-01

    Persistent midwinter cold air pools produce multi-day periods of cold, dreary weather in valleys and basins. Persistent stable stratification leads to the buildup of pollutants and moisture in the pool. Because the pool sometimes has temperatures below freezing while the air above is warmer, freezing precipitation often occurs with consequent effects on transportation and safety. Forecasting the buildup and breakdown of these cold pools is difficult because the physical mechanisms leading to their formation, maintenance, and destruction have received little study. This paper provides a succinct meteorological definition of a cold pool, develops a climatology of Columbia Basin cold pools, and analyzes remote and in situ temperature and wind sounding data for two winter cold pool episodes that were accompanied by fog and stratus, illustrating many of the physical mechanisms affecting cold pool evolution.

  6. Light absorbing carbon emissions from commercial shipping

    NASA Astrophysics Data System (ADS)

    Lack, Daniel; Lerner, Brian; Granier, Claire; Baynard, Tahllee; Lovejoy, Edward; Massoli, Paola; Ravishankara, A. R.; Williams, Eric

    2008-07-01

    Extensive measurements of the emission of light absorbing carbon aerosol (LAC) from commercial shipping are presented. Vessel emissions were sampled using a photoacoustic spectrometer in the Gulf of Mexico region. The highest emitters (per unit fuel burnt) are tug boats, thus making significant contributions to local air quality in ports. Emission of LAC from cargo and non cargo vessels in this study appears to be independent of engine load. Shipping fuel consumption data (2001) was used to calculate a global LAC contribution of 133(+/-27) Ggyr-1, or ~1.7% of global LAC. This small fraction could have disproportionate effects on both air quality near port areas and climate in the Arctic if direct emissions of LAC occur in that region due to opening Arctic sea routes. The global contribution of this LAC burden was investigated using the MOZART model. Increases of 20-50 ng m-3 LAC (relative increases up to 40%) due to shipping occur in the tropical Atlantic, Indonesia, central America and the southern regions of South America and Africa.

  7. A variable passive low-frequency absorber

    NASA Astrophysics Data System (ADS)

    Larsen, Niels Werner; Thompson, Eric R.; Gade, Anders Christian

    2005-04-01

    Multi-purpose concert halls face a dilemma. They can host classical music concerts, rock concerts and spoken word performances in a matter of a short period. These different performance types require significantly different acoustic conditions in order to provide the best sound quality to both the performers and the audience. A recommended reverberation time for classical music may be in the range of 1.5-2 s for empty halls, where rock music sounds best with a reverberation time around 0.8-1 s. Modern rhythmic music often contains high levels of sound energy in the low frequency bands but still requires a high definition for good sound quality. Ideally, the absorption of the hall should be adjustable in all frequency bands in order to provide good sound quality for all types of performances. The mid and high frequency absorption is easily regulated, but adjusting the low-frequency absorption has typically been too expensive or requires too much space to be practical for multi-purpose halls. Measurements were made on a variable low-frequency absorber to develop a practical solution to the dilemma. The paper will present the results of the measurements as well as a possible design.

  8. Improvement of Absorber's Performance by a Surfactant

    NASA Astrophysics Data System (ADS)

    Nishimura, Nobuya; Nomura, Tomohiro; Iyota, Hiroyuki; Kawakami, Ryuichiro

    Effects of an addition of surfactant to a lithium bromide aqueous solution have been investigated experimentally. N-octanol was used as a surfactant. The Marangoni convection occurred at/beneath the solution surface in the very beginning of steam absorption was observed both by a real-time type laser holographic visualization and by temperature measurements with extremely fine gauge thermocouples. Generation and growth of the Marangoni convection were both observed and evaluated quantitatively by the flow visualization. Furthermore, solution's surface temperatures with and without addition of the surfactant were measured minutely. Cell's formation pattern and migration speed at the surface were measured varying the initial surfactant's concentration ranging from 0 to 50000 ppm and the shallow liquid layer thickness ranging from 2 to 5 mm. And spacio-temporal scales of the Marangoni convection were determined. Also solution temperature changes at the surface were compared. Temperature increases when the surfactant was added to its solubility limit became almost double than that case of no surfactant. From these temperature differences, effects of the surfactant on absorber's performances were estimated by a calculation quantitatively with diffusion coefficient as an evaluation value.

  9. Transient QED effects in absorbing dielectrics

    NASA Astrophysics Data System (ADS)

    Wubs, Martijn; Suttorp, L. G.

    2001-04-01

    The spontaneous-emission rate of a radiating atom reaches its time-independent equilibrium value after an initial transient regime. In this paper, we consider the associated relaxation effects of the spontaneous-decay rate of atoms in dispersive and absorbing dielectric media for atomic-transition frequencies near material resonances. A quantum mechanical description of such media is furnished by a damped-polariton model in which absorption is taken into account through coupling to a bath. We show how all field and matter operators in this theory can be expressed in terms of the bath operators at an initial time. The consistency of these solutions for the field and matter operators are found to depend on the validity of certain velocity sum rules. The transient effects in the spontaneous-decay rate are studied with the help of several specific models for the dielectric constant, which are shown to follow from the general theory by adopting particular forms of the bath coupling constant.

  10. Space Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Stephan, Ryan; Hodgson, Ed; Izenson, Mike; Chen, Weibo

    2012-01-01

    A system for non-venting thermal control for spacesuits was built by integrating two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s flexible version of the Lithium Chloride Absorber Radiator (LCAR). This SEAR system was tested in relevant thermal vacuum conditions. These tests show that a 1 m2 radiator having about three times as much absorption media as in the test article would be required to support a 7 hour spacewalk. The serial flow arrangement of the LCAR of the flexible version proved to be inefficient for venting non-condensable gas (NCG). A different LCAR packaging arrangement was conceived wherein the Portable Life Support System (PLSS) housing would be made with a high-strength carbon fiber composite honeycomb, the cells of which would be filled with the chemical absorption media. This new packaging reduces the mass and volume impact of the SEAR on the Portable Life Support System (PLSS) compared to the flexible design. A 0.2 sq m panel with flight-like honeycomb geometry is being constructed and will be tested in thermal and thermal vacuum conditions. Design analyses forecast improved system performance and improved NCG control. A flight-like regeneration system also is also being built and tested. Design analyses for the structurally integrated prototype as well as the earlier test data show that SEAR is not only practical for spacesuits but also has useful applications in spacecraft thermal control.

  11. Multifunctional Space Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Hodgson, Ed; Izenson, Mike; Chen, Weibo

    2013-01-01

    A system for non-venting thermal control for spacesuits was built by integrating two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's flexible version of the Lithium Chloride Absorber Radiator (LCAR). This SEAR system was tested in relevant thermal vacuum conditions. These tests show that a 1 sq m radiator having about three times as much absorption media as in the test article would be required to support a 7 hour spacewalk. The serial flow arrangement of the LCAR of the flexible version proved to be inefficient for venting non-condensable gas (NCG). A different LCAR packaging arrangement was conceived wherein the Portable Life Support System (PLSS) housing would be made with a high-strength carbon fiber composite honeycomb, the cells of which would be filled with the chemical absorption media. This new packaging reduce the mass and volume impact of the SEAR on the Portable Life Support System (PLSS) compared to the flexible design. A 0.2 sq m panel with flight-like honeycomb geometry is being constructed and will be tested in thermal and thermal vacuum conditions. Design analyses forecast improved system performance and improved NCG control. A flight-like regeneration system also is also being built and tested. Design analyses for the structurally integrated prototype as well as the earlier test data show that SEAR is not only practical for spacesuits but also has useful applications in spacecraft thermal control.

  12. Spacesuit Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Hodgson, Ed; Izenso, Mike; Chan, Weibo; Cupples, Scott

    2011-01-01

    For decades advanced spacesuit developers have pursued a regenerable, robust non-venting system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's lithium chloride Heat Pump Radiator (HPR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. The SEAR is evacuated at the onset of operations and thereafter, the water vapor absorption rate of the HPR maintains a low pressure environment for the SWME to evaporate effectively. This water vapor captured by solid LiCl in the HPR with a high enthalpy of absorption, results in sufficient temperature lift to reject most of the heat to space by radiation. After the sortie, the HPR would be heated up in a regenerator to drive off and recover the absorbed evaporant. A one-fourth scale prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The HPR was able to stably reject 60 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

  13. Absorber Coatings for Mid-Infrared Astrophysics

    NASA Astrophysics Data System (ADS)

    Baker, Dahlia Anne; Wollack, Edward; Rostem, Karwan

    2017-01-01

    Control over optical response is an important aspect of instrument design for astrophysical imaging. Here we consider a mid-infrared absorber coating proposed for use on HIRMES (High Resolution Mid-Infrared Spectrometer), a cryogenic spectrometer which will fly on the SOFIA (Stratospheric Observatory for Infrared Astronomy) aircraft. The aim of this effort is to develop an absorptive coating for the 20-200 microns spectral range based on a graphene loaded epoxy binder (Epotek 377H) and glass microsphere scatterers (3M K1). The coatings electromagnetic response was modeled using a Matlab script and the glass microspheres were characterized by the measured size distribution, the dielectric constant, and the filling fraction. Images of the microspheres taken by a microscope were used to determine the size distribution with an ImageJ particle analysis program. Representative test samples for optical evaluation were fabricated for characterization via infrared Fourier transform spectroscopy. The optical tests will determine the material’s absorptance and reflectance. These test results will be compared to the modeled response.

  14. Semiconductor nanowire optical antenna solar absorbers.

    PubMed

    Cao, Linyou; Fan, Pengyu; Vasudev, Alok P; White, Justin S; Yu, Zongfu; Cai, Wenshan; Schuller, Jon A; Fan, Shanhui; Brongersma, Mark L

    2010-02-10

    Photovoltaic (PV) cells can serve as a virtually unlimited clean source of energy by converting sunlight into electrical power. Their importance is reflected in the tireless efforts that have been devoted to improving the electrical and structural properties of PV materials. More recently, photon management (PM) has emerged as a powerful additional means to boost energy conversion efficiencies. Here, we demonstrate an entirely new PM strategy that capitalizes on strong broad band optical antenna effects in one-dimensional semiconductor nanostructures to dramatically enhance absorption of sunlight. We show that the absorption of sunlight in Si nanowires (Si NWs) can be significantly enhanced over the bulk. The NW's optical properties also naturally give rise to an improved angular response. We propose that by patterning the silicon layer in a thin film PV cell into an array of NWs, one can boost the absorption for solar radiation by 25% while utilizing less than half of the semiconductor material (250% increase in the light absorption per unit volume of material). These results significantly advance our understanding of the way sunlight is absorbed by one-dimensional semiconductor nanostructures and provide a clear, intuitive guidance for the design of efficient NW solar cells. The presented approach is universal to any semiconductor and a wide range of nanostructures; as such, it provides a new PV platform technology.

  15. Design of a multiband terahertz perfect absorber

    NASA Astrophysics Data System (ADS)

    Dan, Hu; Hong-yan, Wang; Zhen-jie, Tang; Xi-wei, Zhang; Lin, Ju; Hua-ying, Wang

    2016-03-01

    A thin-flexible multiband terahertz metamaterial absorber (MA) has been investigated. Each unit cell of the MA consists of a simple metal structure, which includes the top metal resonator ring and the bottom metallic ground plane, separated by a thin-flexible dielectric spacer. Finite-difference time domain simulation indicates that this MA can achieve over 99% absorption at frequencies of 1.50 THz, 3.33 THz, and 5.40 THz by properly assembling the sandwiched structure. However, because of its asymmetric structure, the MA is polarization-sensitive and can tune the absorptivity of the second absorption peak by changing the incident polarization angle. The effect of the error of the structural parameters on the absorption efficiency is also carefully analyzed in detail to guide the fabrication. Moreover, the proposed MA exhibits high refractive-index sensing sensitivity, which has potential applications in multi-wavelength sensing in the terahertz region. Project supported by the National Natural Science Foundation of China (Grant No. 11504006), the Key Scientific Research Project of Higher Education of Henan Province, China (Grant No. 15A140002), and the Science and Technology Planning Project of Henan Province, China (Grant No. 142300410366).

  16. [Surgery of Lower Eyelid Ectropion with the Tarsal Strip Procedure, Using Absorbable or Non-Absorbable Sutures for Periosteal Fixation].

    PubMed

    Sommer, F

    2017-01-01

    Purpose Tightening of the lower eyelid is often performed and many techniques are available. This paper describes the outcome of lower eyelid ectropion repair using the lateral tarsal strip procedure. Periosteal fixation of the tarsal strip can be performed with absorbable or non-absorbable sutures. This study compares the surgical results of periosteal fixation of the tarsal strip with a) absorbable and b) non-absorbable suture. Methods Of 206 patients who underwent surgery, data from 161 were available. During the 6 month follow-up period, suture material, recurrence rates and complications were assessed. The analysis was based on photo documentation, surgery reports and patient statements. In all cases surgery was performed by the same surgeon. Results After 6 months, patients showed similar recurrence rates, regardless of whether periosteal fixation of the tarsal strip had been performed with absorbable (61 patients) or non-absorbable (100 patients) material. Only a few complications occurred, including wound healing problems and one allergic reaction in the non-absorbable group. Conclusions In cases of lower eyelid ectropion, the surgical outcome after the tarsal strip procedure was similar for absorbable and non-absorbable sutures.

  17. Effect of the bio-absorbent on the microwave absorption property of the flaky CIPs/rubber absorbers

    NASA Astrophysics Data System (ADS)

    Cheng, Yang; Xu, Yonggang; Cai, Jun; Yuan, Liming; Zhang, Deyuan

    2015-09-01

    Microwave absorbing composites filled with flaky carbonyl iron particles (CIPs) and the bio-absorbent were prepared by using a two-roll mixer and a vulcanizing machine. The electromagnetic (EM) parameters were measured by a vector network analyzer and the reflection loss (RL) was measured by the arch method in the frequency range of 1-4 GHz. The uniform dispersion of the absorbents was verified by comparing the calculated RL with the measured one. The results confirm that as the bio-absorbent was added, the permittivity was increased due to the volume content of absorbents, and the permeability was enlarged owing to the volume content of CIPs and interactions between the two absorbents. The composite filled with bio-absorbents achieved an excellent absorption property at a thickness of 1 mm (minimum RL reaches -7.8 dB), and as the RL was less than -10 dB the absorption band was widest (2.1-3.8 GHz) at a thickness of 2 mm. Therefore, the bio-absorbent is a promising additive candidate on fabricating microwave absorbing composites with a thinner thickness and wider absorption band.

  18. MoSi absorber photomask for 32nm node

    NASA Astrophysics Data System (ADS)

    Konishi, Toshio; Kojima, Yosuke; Takahashi, Hiroyuki; Tanabe, Masato; Haraguchi, Takashi; Lamantia, Matthew; Fukushima, Yuichi; Okuda, Yoshimitsu

    2008-05-01

    The development of semiconductor process for 32nm node is in progress. Immersion lithography has been introduced as an extension of 193nm lithograpy. In addition, DPL (Double patterning lithography) is becoming a strong candidate of next generation lithography. The extension of optical lithography increases more mask complexity and tighter specification of photomasks. CD performance is the most important issue in the advanced photomask technology. However, it is expected that conventional mask cannot satisfy the required mask specifications for 32nm node and beyond. Most of CD errors are contributed to the dry etching process. Mask CD variation is greatly influenced by the loading effect from dry etching of the absorber. As the required accuracy of the mask arises, Cr absorber thickness has been gradually thinner. CD linearity with the thinner Cr absorber thickness has better performance. However, it is difficult to apply thinner Cr absorber thickness simply under the condition of OD > 3, which is needed for wafer printing. So, we adopted MoSi absorber instead of conventional Cr absorber, because MoSi absorber has less micro and global loading effect than that of Cr absorber. By using MoSi absorber, we can reduce Cr thickness as a hardmask. The thinner Cr hardmask allows for reduce resist thickness and become same condition for conventional EB resist lithography. The lithography performances were confirmed by the simulation and wafer printing. The new MoSi absorber mask behaves similar to the conventional Cr absorber mask. The adoption of super thin Cr as a hardmask made it possible to reduce resist thickness. By the application of the thin resist and the latest tools, we'll improve the mask performance to meet the 32 nm generation specification.

  19. HOM absorbers for ERL cryomodules at BNL

    SciTech Connect

    Hahn,H.; Ben-Zvi, I.; Hammons, L.; Xu, W.

    2009-09-20

    The physics needs and technical requirements for several future accelerator projects at the Relativistic Heavy Ion Collider (RHIC) all involve electron Energy Recovery Linacs (ERL). The required high-current, high-charge operating parameters make effective higher-order-mode (HOM) damping mandatory and the development of HOM dampers for a prototypical five-cell cavity is actively pursued. An experimental five-cell niobium cavity with ferrite dampers has been constructed, and effective HOM damping has been demonstrated at room and superconducting (SC) temperatures. A novel type of ferrite damper around a ceramic break has been developed for the ERL electron gun and prototype tests are also reported. Contemplated future projects are based on assembling a chain of superconducting cavities in a common cryomodule with the dampers placed in the cold space between the cavities, imposing severe longitudinal space constraints. Various damper configurations have been studied by placing them between two five-cell copper cavities. Measured and simulated copper cavity results, external Q-values of possible dampers and fundamental mode losses are presented.

  20. The Cold Mass Support System and the Helium Cooling System for theMICE Focusing Solenoid

    SciTech Connect

    Yang, Stephanie Q.; Green, Michael A.; Lau, Wing W.; Senanayake,Rohan S.; Witte, Holger

    2006-08-10

    The heart of the absorber focus coil (AFC) module for the muon ionization cooling experiment (MICE) is the two-coil superconducting solenoid that surrounds the muon absorber. The superconducting magnet focuses the muons that are cooled using ionization cooling, in order to improve the efficiency of cooling. The coils of the magnet may either be run in the solenoid mode (both coils operate at the same polarity) or the gradient (the coils operate at opposite polarity). The AFC magnet cold mass support system is designed to carry a longitudinal force up to 700 kN. The AFC module will be cooled using three pulse tube coolers that produce 1.5 W of cooling at 4.2 K. One of the coolers will be used to cool the liquid (hydrogen or helium) absorber used for ionization cooling. The other two coolers will cool the superconducting solenoid. This report will describe the MICE AFC magnet. The cold mass supports will be discussed. The reasons for using a pulsed tube cooler to cool this superconducting magnet will also be discussed.

  1. Microwave Absorbing Properties of Metallic Glass/Polymer Composites

    DTIC Science & Technology

    2011-09-01

    Technical Report ARWSB-TR-11022 Microwave Absorbing Properties of Metallic Glass/Polymer Composites Stephen Bartolucci...Technical 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Microwave Absorbing Properties of Metallic Glass/Polymer Composites 5a. CONTRACT...this study, the microwave absorption characteristics of metallic glass / polymer composites were investigated. Electromagnetic wave absorption

  2. Shock-absorbing caster wheel is simple and compact

    NASA Technical Reports Server (NTRS)

    Kindley, R. J.

    1968-01-01

    Compact shock-absorbing caster wheel mitigates or absorbs shock by a compressible tire which deforms into a cavity between its inner edge and the wheel hub. A tee-shaped annular ring embedded in the tire distributes loads more uniformly throughout both wheel and tire.

  3. Science on a Roll. Part One: Absorbing Inquiry.

    ERIC Educational Resources Information Center

    Brendzel, Sharon

    2002-01-01

    Presents an activity that tests the absorbency of different brands of paper towels. Suggests making this activity into an open-ended inquiry type of activity. Includes sample questions to guide students, topics for class discussion, and sample methods of using the absorbency activity. (KHR)

  4. Performance of an artificial absorber for truncating FEM meshes

    NASA Astrophysics Data System (ADS)

    Gong, Jian; Volakis, John L.

    1995-01-01

    We investigate the effectiveness of an artificial absorber for truncating finite element (FE) meshes. Specifically, we present the implementation of a novel mesh truncation approach using a perfectly matched anisotropic absorber for waveguides and stripline circuits. This truncation scheme is useful in many applications, including antennas, scattering, and microwave circuits.

  5. Physically absorbable reagents-collectors in elementary flotation

    SciTech Connect

    S.A. Kondrat'ev; I.G. Bochkarev

    2007-09-15

    Based on the reviewed researches held at the Institute of Mining, Siberian Branch, Russian Academy of Sciences, the effect of physically absorbable reagents-collectors on formation of a flotation complex and its stability in turbulent pulp flows in flotation machines of basic types is considered. The basic requirements for physically absorbable reagents-collectors at different flotation stages are established.

  6. An Absorbing Look at Terry-Cloth Towels

    ERIC Educational Resources Information Center

    Moyer, Richard; Everett, Susan

    2010-01-01

    This article describes a lesson where students explore the absorbency of several towels with different weaves and weights. The lesson follows the 5E learning-cycle model and incorporates engineering in the sense of product testing with a focus on the relationship between the weave of a towel and its absorbency. The National Science Education…

  7. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 27.475 Section... be in their static position and the shock absorbers to be in their most critical position. ... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and...

  8. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Tires and shock absorbers. 27.475 Section... be in their static position and the shock absorbers to be in their most critical position. ... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and...

  9. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Tires and shock absorbers. 27.475 Section... be in their static position and the shock absorbers to be in their most critical position. ... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and...

  10. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Tires and shock absorbers. 27.475 Section... be in their static position and the shock absorbers to be in their most critical position. ... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and...

  11. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Tires and shock absorbers. 27.475 Section... be in their static position and the shock absorbers to be in their most critical position. ... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and...

  12. Nylon shock absorber prevents injury to parachute jumpers

    NASA Technical Reports Server (NTRS)

    Mandel, J. A.

    1966-01-01

    Nylon shock absorbers reduce the canopy-opening shock of a parachute to a level that protects the wearer from injury. A shock absorber is mounted on each of the four risers between the shroud lines and the harness. Because of their size and location, they pose no problem in repacking the chute and harness after a jump.

  13. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Absorbable implant (scleral buckling method). 886.3300 Section 886.3300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a...

  14. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Absorbable implant (scleral buckling method). 886.3300 Section 886.3300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a...

  15. Photochromic And Thermochromic Pigments For Solar Absorbing-Reflecting Coatings

    NASA Astrophysics Data System (ADS)

    Novinson, Thomas

    1987-11-01

    Both photochromic and thermochromic compounds were synthesized and physical measurements were made to determine coefficients of relectance, absorbance and emission. The most interesting group of thermochromic compounds are related to silver tctraiodomercurate and the most interesting photochromic compounds are substituted benzoindolinopyrospirans. The synthesis and optical reflectance and absorbance properties of other classes of compounds are also reported.

  16. 21 CFR 880.5300 - Medical absorbent fiber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... and that is used for applying medication to, or absorbing small amounts of body fluids from, a patient's body surface. Absorbent fibers intended solely for cosmetic purposes are not included in...

  17. 21 CFR 880.5300 - Medical absorbent fiber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... and that is used for applying medication to, or absorbing small amounts of body fluids from, a patient's body surface. Absorbent fibers intended solely for cosmetic purposes are not included in...

  18. Why muscle is an efficient shock absorber.

    PubMed

    Ferenczi, Michael A; Bershitsky, Sergey Y; Koubassova, Natalia A; Kopylova, Galina V; Fernandez, Manuel; Narayanan, Theyencheri; Tsaturyan, Andrey K

    2014-01-01

    Skeletal muscles power body movement by converting free energy of ATP hydrolysis into mechanical work. During the landing phase of running or jumping some activated skeletal muscles are subjected to stretch. Upon stretch they absorb body energy quickly and effectively thus protecting joints and bones from impact damage. This is achieved because during lengthening, skeletal muscle bears higher force and has higher instantaneous stiffness than during isometric contraction, and yet consumes very little ATP. We wish to understand how the actomyosin molecules change their structure and interaction to implement these physiologically useful mechanical and thermodynamical properties. We monitored changes in the low angle x-ray diffraction pattern of rabbit skeletal muscle fibers during ramp stretch compared to those during isometric contraction at physiological temperature using synchrotron radiation. The intensities of the off-meridional layer lines and fine interference structure of the meridional M3 myosin x-ray reflection were resolved. Mechanical and structural data show that upon stretch the fraction of actin-bound myosin heads is higher than during isometric contraction. On the other hand, the intensities of the actin layer lines are lower than during isometric contraction. Taken together, these results suggest that during stretch, a significant fraction of actin-bound heads is bound non-stereo-specifically, i.e. they are disordered azimuthally although stiff axially. As the strong or stereo-specific myosin binding to actin is necessary for actin activation of the myosin ATPase, this finding explains the low metabolic cost of energy absorption by muscle during the landing phase of locomotion.

  19. Thermally tunable water-substrate broadband metamaterial absorbers

    NASA Astrophysics Data System (ADS)

    Pang, Yongqiang; Wang, Jiafu; Cheng, Qiang; Xia, Song; Zhou, Xiao Yang; Xu, Zhuo; Cui, Tie Jun; Qu, Shaobo

    2017-03-01

    The naturally occurring water has frequency dispersive permittivity at microwave frequencies and thus is a promising constituent material for broadband absorbers. Here, we develop water as the dielectric spacer in the substrate of metal-backed metamaterial (MM) absorbers. The designed substrate is a hybrid of water and a low-permittivity dielectric material. Such a design allows tight packaging of water and easy fabrication of the absorber. We obtain broadband absorption at temperatures of interest by designing the hybrid substrate and MM inclusions. Additionally, the absorption performance of the water-substrate MM absorbers could be tunable according to the environment temperature. We experimentally demonstrate the broadband and thermally tunable absorption performance. We expect that water could replace dielectric layers in other structural MM absorbers to achieve the broadband and thermally tunable absorption performance.

  20. Absorbency properties of different brands of standardized endodontic paper points.

    PubMed

    Pumarola-Suñé, J; Solá-Vicens, L; Sentís-Vilalta, J; Canalda-Sahli, C; Brau-Aguadé, E

    1998-12-01

    A comparative study of the absorbency properties of different endodontic paper points has been conducted. Twenty standardized absorbent paper points, size 30, from 13 bands (Dentaline, Zipperer, Kerr, Diadent, Roeko novo, Roeko color, Maillefer, P.D., Schein, Spectrapoint, Proclinic, Euronda, and Alpro) of 12 manufacturers were tested. Each dry paper point was weighted using an electronic laboratory balance. A length of 16 mm from the tip was then lowered in distilled water for 5 s, the paper point was weighted again, and the difference between both measurements was taken as the value of the fluid absorbed. Diadent, Kerr, and Dentalite showed significantly higher absorbencies (p < 0.05) than standardized paper points of the remaining brands. The study demonstrates a wide variation in the absorbency properties of this dental accessory.