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1

Clumpy cold dark matter  

NASA Technical Reports Server (NTRS)

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.

Silk, Joseph; Stebbins, Albert

1993-01-01

2

A Submillimeter Galaxy Illuminating its Circumgalactic Medium: Ly? Scattering in a Cold, Clumpy Outflow  

NASA Astrophysics Data System (ADS)

We report the detection at 850 ?m of the central source in SSA22-LAB1, the archetypal "Lyman-? Blob" (LAB), a 100 kpc scale radio-quiet emission-line nebula at z = 3.1. The flux density of the source, S 850 = 4.6 ± 1.1 mJy, implies the presence of a galaxy or group of galaxies with a total luminosity of L IR ? 1012 L ?. The position of an active source at the center of a ~50 kpc radius ring of linearly polarized Ly? emission detected by Hayes et al. suggests that the central source is leaking Ly? photons preferentially in the plane of the sky, which undergo scattering in H I clouds at a large galactocentric radius. The Ly? morphology around the submillimeter detection is reminiscent of a biconical outflow, and the average Ly? 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 Ly? emission and morphology. Less clear is the history of the cold gas in the circumgalactic medium being traced by Ly?: 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?

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

2014-09-01

3

The COS Cold Absorber Puzzle: Understanding the Metallicity and Phase of the Circumgalactic Medium  

NASA Astrophysics Data System (ADS)

Grasping the way gas gets in and out of galaxies is fundamental to our understanding of galaxy formation and evolution, and COS observations are slowly providing a better picture of these gas flows. Recent COS observations of the circumgalactic medium {CGM} have revealed two puzzles: the bimodal metallicity distribution of Lyman Limit Systems {LLSs} proximate to galaxies {Lehner et al. 2013} and the low volume density for cold absorbers in the CGM {Werk et al. 2014}. We propose to address both of these issues through the execution and analysis of grid-based cosmological hydrodynamics simulations of unprecedented resolution. By modeling galaxies at very high resolution using a physically-motivated, momentum-based feedback method, we will perform the first grid-based studies of the CGM at this scale, allowing us to identify analogs to the observed cold absorber population responsible for these puzzles. We will trace the simulated cold absorbers through time to understand their origins, producing a full picture of how they acquire and expel their gas.

Hummels, Cameron

2014-10-01

4

Search for cold gas in strong Mg II absorbers at 0.5 < z < 1.5: nature and evolution of 21-cm absorbers  

NASA Astrophysics Data System (ADS)

We report four new detections of 21-cm absorption from a systematic search of 21-cm absorption in a sample of 17 strong (rest equivalent width, Wr(Mg ii?2796) ? 1 Å) intervening Mg ii absorbers at 0.5 < zabs < 1.5. We also present 20-cm milliarcsecond scale maps of 40 quasars having 42 intervening strong Mg ii absorbers for which we have searched for 21-cm absorption. These maps are used to understand the dependence of 21-cm detection rate on the radio morphology of the background quasar and address the issues related to the covering factor of absorbing gas. Combining 21-cm absorption measurements for 50 strong Mg ii systems from our surveys with the measurements from literature, we obtain a sample of 85 strong Mg ii absorbers at 0.5 < zabs < 1 and 1.1 < zabs < 1.5. We present detailed analysis of this 21-cm absorption sample, taking into account the effect of the varying 21-cm optical depth sensitivity and covering factor associated with the different quasar sight lines. We find that the 21-cm detection rate is higher towards the quasars with flat or inverted spectral index at cm wavelengths. About 70% of 21-cm detections are towards the quasars with linear size, LS < 100 pc. The 21-cm absorption lines having velocity widths, ?V > 100 km s-1 are mainly seen towards the quasars with extended radio morphology at arcsecond scales. However, we do not find any correlation between the integrated 21-cm optical depth, ??dv, or the width of 21-cm absorption line, ?V, with the LS measured from the milliarcsecond scale images. All this can be understood if the absorbing gas is patchy with a typical correlation length of ~30-100 pc. We confirm our previous finding that the 21-cm detection rate for a given optical depth threshold can be increased by up to a factor 2 by imposing the following additional constraints: Mg ii doublet ratio < 1.1, W(Mg ii)/W(Fe ii) < 1.47 and W(Mg i)/W(Mg ii) > 0.27. This suggests that the probability of detecting 21-cm absorption is higher in the systems with high N(H i). We show that within the measurement uncertainty, the 21-cm detection rate in strong Mg ii systems is constant over 0.5 < zabs < 1.5, i.e., over ~30% of the total age of universe. We show that the detection rate can be underestimated by up to a factor 2 if 21-cm optical depths are not corrected for the partial coverage estimated using milliarcsecond scale maps. Since stellar feedback processes are expected to diminish the filling factor of cold neutral medium over 0.5 < z < 1, this lack of evolution in the 21-cm detection rate in strong Mg ii absorbers is intriguing. Large blind surveys of 21-cm absorption lines with the upcoming Square Kilometre Array pathfinders will provide a complete view of the evolution of cold gas in galaxies and shed light on the nature ofMg ii systems and DLAs, and their relationship with stellar feedback processes. Table 4 and appendices are available in electronic form at http://www.aanda.org

Gupta, N.; Srianand, R.; Petitjean, P.; Bergeron, J.; Noterdaeme, P.; Muzahid, S.

2012-08-01

5

Multiple Scattering in Clumpy Media. I. Escape of Stellar Radiation from a Clumpy Scattering Environment  

NASA Astrophysics Data System (ADS)

We studied the radiative transfer in a spherical, two-phase clumpy medium, in which coherent, nonconservative scattering is the dominant opacity source and where the source of photons is situated at the center. The structure of the medium is random but statistically homogeneous and is characterized by the density ratio between the low- and high-density phases, the optical depth radius of the equivalent homogeneous dust distribution, the filling factor of high-density clumps, and the length scale of individual clumps. We examined in detail the cloud mass spectrum, the distribution of optical depths, and the apparent fractal nature of the projected cloud structures. The photometric characteristics of the clumpy scattering system are studied as a function of density contrast between the two phases, of the filling factor, and of the length scale of high-density clumps, and they are compared with those of homogeneous, constant-density distributions of equal effective optical depth. Direction-averaged surface brightness distributions of the scattered light are studied for both optically thick and optically thin cases, which reveal the important role of scattering by the optically thin interclump medium. The conversion of UV/optical/near-IR radiation into thermal far-IR dust radiation in a dusty system is profoundly affected by the structure of the medium; the homogeneous, constant-density distribution always provides the highest conversion efficiency for any given geometry and dust mass. The effective optical depth of a clumpy distribution is known not to scale linearly with the equivalent optical depth of a homogeneous distribution of equal dust mass; this leads to effective attenuation laws that differ from the original opacity law assumed for the dust in the system. The expected reddening is substantially reduced for clumpy media. Finally, since the scattering response of a clumpy system is consistently that of an equivalent system of lower effective optical depth and lower effective albedo, efforts to determine the dust albedo of real systems with clumpy dust distributions by employing models, which are homogeneous, can lead to a bias toward albedo values that are too low.

Witt, Adolf N.; Gordon, Karl D.

1996-06-01

6

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

SciTech Connect

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.

Wang Jianmin; Cheng Cheng; Li Yanrong [Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049 (China)

2012-04-01

7

A Deep Search for Faint Galaxies Associated with Very Low-redshift C IV Absorbers: A Case with Cold-accretion Characteristics  

NASA Astrophysics Data System (ADS)

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 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 gal = 0.00283) at an impact parameter of ? = 190 kpc or with a very faint dwarf irregular galaxy at ? = 23 kpc, which is closer to the sightline but has a larger redshift difference (z gal = 0.00107, i.e., ?v = 724 km s-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 "ancient outflow", 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. Based on observations obtained with the NASA/ESA Hubble Space Telescope operated at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Also, based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the US, Italy, and Germany. LBT Corporation partners are the University of Arizona, on behalf of the Arizona University System; Instituto Nazionale do Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max Planck Society, the Astrophysical Institute of Potsdam, and Heidelberg University; Ohio State University, and the Research Corporation, on behalf of the University of Notre Dame, the University of Minnesota, and the University of Virginia. Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution.

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

2013-12-01

8

Massive Black Hole Pairs in Clumpy, Self-gravitating Circumnuclear Disks: Stochastic Orbital Decay  

NASA Astrophysics Data System (ADS)

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 •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 •2 with massive clumps M 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 •2/M 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.

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

2013-11-01

9

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

SciTech Connect

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.

Fiacconi, Davide; Mayer, Lucio; Roškar, Rok [Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)] [Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Colpi, Monica, E-mail: fiacconi@physik.uzh.ch [Dipartimento di Fisica 'G. Occhialini', Università di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano (Italy)] [Dipartimento di Fisica 'G. Occhialini', Università di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano (Italy)

2013-11-01

10

Escape of Stellar Radiation from a Clumpy Scattering Environment  

NASA Astrophysics Data System (ADS)

The physics of the interstellar medium (ISM) allows the coexistence of several density states, and observations confirm the widespread occurrence of a cloudy or clumpy structure of the ISM on many length scales. We have investigated the effects of such a clumpy structure upon the transfer of light through a dusty scattering medium by means of a Monte Carlo radiative transfer code. Application of this code can be found in dusty environments in star-forming regions, reflection nebulae, and dusty galaxies. The specific case studied here concerned the escape of continuum radiation originating from a central point source, propagating through a homogeneously clumpy medium which was terminated by a spherical boundary. We examined the transfer as a function of the ratio of the densities of the clumps and the inter-clump medium for two cases, the case of constant mass and the case of constant density of the clumps. A range of filling factors and typical clumpy sizes were examined. We characterize the scattering system by the distribution of radial optical depths and the mass spectrum of clumps, which result from the assumption of given filling factors and clump sizes. A general result is that transfer through a clumpy medium is equivalent to that through a homogeneous medium of substantially lower optical depth and lower dust albedo, as far as the escape of direct stellar and scattered radiation is concerned. The role of the interclump medium is important when clumps themselves are optically thick. The ratio of far-IR to optical radiation from a clumpy environment is substantially lower than that ratio from a homogeneous dust distribution containing the same dust mass. This work was supported by NASA through LTSA Grant NAGW-3168 to The University of Toledo.

Gordon, K. D.; Witt, A. N.

1994-12-01

11

Patterns of Super Star Cluster Formation in `Clumpy' Starburst Galaxies  

E-print Network

We present preliminary results from a Hubble Space Telescope (HST) WFPC2 investigation of spatial and temporal distributions of star clusters in the clumpy irregular galaxy NGC 7673 and the starburst spirals NGC 3310 and Haro 1. We compare the spectral energy distributions of star clusters in the large clumps in NGC 7673 to model calculations of stellar clusters of various ages. We also propose that the presence of super star clusters in clumps seems to be a feature of intense starbursts.

J. S. Gallagher; N. L. Homeier; C. J. Conselice; WFPC-2IDT

2000-02-07

12

Radiative Transfer in Galactic Environments with Clumpy Dust  

NASA Astrophysics Data System (ADS)

The interstellar medium (ISM) in both our Galaxy and in other late-type galaxies has an inhomogeneous or clumpy structure. Using Monte Carlo techniques, we have investigated the affects of this clumpy structure on the radiative transfer in different galactic environments. These galactic environments include those dealt with in Witt, Thronson, & Capuano (1992, ApJ, 393, 611) with the added dimension of a two phase dust structure described by the total amount of dust, the filling factor of the high density clumps, and the density ratio between the high and low density phases of the ISM. In addition, the parameters describing the dust properties (the albedo and scattering phase function asymmetry) have been compiled from the most recent Galactic observations from the IR to the UV. The resulting attenuation curves show a wide range of behavior, including a reduction in the strength of the 2175 Angstroms bump and an overall flattening of the slope. The reddening vectors for various colors are nonlinear and, usually, have a maximicrons value after which they return to their non-attenuated colors or even to bluer colors. From this result, the structure of the ISM in a galaxy may be determined from its integrated colors. We also deduce the total attenuation in spiral disks at V is more a function of the structure than a function of the total amount of dust and normally does not exceed 1--2 magnitudes. Using an assumed spectral energy distribution, the calculated FIR/FOPT indicates the ISM in ultra-luminous interacting galaxies has a more homogeneous structure than the ISM in noninteractive galaxies. This work was supported by NASA through LTSA Grant NAGW-3168 to The University of Toledo.

Gordon, K. D.; Witt, A. N.

1995-05-01

13

3-D Models of Embedded High-Mass Stars: Effects of a Clumpy Circumstellar Medium  

E-print Network

We use 3-D radiative transfer models to show the effects of clumpy circumstellar material on the observed infrared colors of high mass stars embedded in molecular clouds. We highlight differences between 3-D clumpy and 1-D smooth models which can affect the interpretation of data. We discuss several important properties of the emergent spectral energy distribution (SED): More near-infrared light (scattered and direct from the central source) can escape than in smooth 1-D models. The near- and mid-infrared SED of the same object can vary significantly with viewing angle, depending on the clump geometry along the sightline. Even the wavelength-integrated flux can vary with angle by more than a factor of two. Objects with the same average circumstellar dust distribution can have very different near-and mid-IR SEDs depending on the clump geometry and the proximity of the most massive clump to the central source. Although clumpiness can cause similar objects to have very different SEDs, there are some observable trends. Near- and mid-infrared colors are sensitive to the weighted average distance of clumps from the central source and to the magnitude of clumpy density variations (smooth-to-clumpy ratio). Far-infrared emission remains a robust measure of the total dust mass. We present simulated SEDs, colors, and images for 2MASS and Spitzer filters. We compare to observations of some UCHII regions and find that 3-D clumpy models fit better than smooth models. In particular, clumpy models with fractal dimensions in the range 2.3-2.8, smooth to clumpy ratios of <50%, and density distributions with shallow average radial density profiles fit the SEDs best.

R. Indebetouw; B. A. Whitney; K. E. Johnson; K. wood

2005-09-04

14

MIXING OF CLUMPY SUPERNOVA EJECTA INTO MOLECULAR CLOUDS  

SciTech Connect

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 potentially consistent with the observed variability in stellar elemental abundances. Supernova contamination of forming planetary systems may be a common, universal process.

Pan Liubin; Desch, Steven J.; Scannapieco, Evan; Timmes, F. X. [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States)

2012-09-01

15

Clumpy Galaxies in CANDELS. I. The Definition of UV Clumps and the Fraction of Clumpy Galaxies at 0.5 < z < 3  

NASA Astrophysics Data System (ADS)

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 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 clumpy changes with the stellar mass (M *) of the galaxies. Low-mass (log (M */M ?) < 9.8) galaxies keep an almost constant f clumpy of ~60% from z ~ 3 to z ~ 0.5. Intermediate-mass and massive galaxies drop their f 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 clumpy trend of massive galaxies; (2) minor mergers are a viable explanation of the f 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 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 */M ?) ~ 10.5 at all redshifts. The clump contribution in the intermediate-mass and massive galaxies is possibly linked to the molecular gas fraction of the galaxies. The clump contribution to the SFR of star-forming galaxies, generally around 4%-10%, also shows dependence on the galaxy M *, but for a given galaxy M *, its dependence on the redshift is mild.

Guo, Yicheng; Ferguson, Henry C.; Bell, Eric F.; Koo, David C.; Conselice, Christopher J.; Giavalisco, Mauro; Kassin, Susan; Lu, Yu; Lucas, Ray; Mandelker, Nir; McIntosh, Daniel M.; Primack, Joel R.; Ravindranath, Swara; Barro, Guillermo; Ceverino, Daniel; Dekel, Avishai; Faber, Sandra M.; Fang, Jerome J.; Koekemoer, Anton M.; Noeske, Kai; Rafelski, Marc; Straughn, Amber

2015-02-01

16

How Cold Is Cold?  

NSDL National Science Digital Library

Heat and cold are often difficult concepts for children to understand. First, our everyday sloppy language gives them a predisposition to such common misconceptions as cold being a substance that moves from place to place. Our colloquial language often re

Richard Konicek-Moran

2008-04-01

17

Reddening and Attenuation by Dust in Galaxies with a Clumpy ISM  

NASA Astrophysics Data System (ADS)

The UV/optical flux and SED of galaxies are strongly affected by the wavelength-dependent attenuation of light by dust internal to galaxies. One important characteristic of such dust is its inhomogeneous, clumpy distribution. We report on new radiative transfer models applicable to galaxies which include a locally random, two-phase ISM with scattering dust. We investigated the effects of varying the geometries of relative star/dust distributions and the effects of dust type (MW dust and SMC dust), in addition to comparing the effects of clumpy and homogeneous dust distributions. Our models cover the wavelength range 1000 Angstroms to 30,000 Angstroms. Increasing column densities of clumpy dust lead to rapidly saturating reddening at low values of E(B-V), resulting in an increasingly gray attenuation, especially in the UV. The determination of an attenuation correction factor in the UV, of major significance for the analysis of the SEDs of UV-selected starburst galaxies in the nearby and distant Universe (i.e. Lyman-break galaxies) from UV spectral characteristics alone is highly geometry- and dust-type-dependent. We show that the spectral characteristics of a sample of UV-selected, nearby starburst galaxies are reproduced most easily with a shell geometry containing clumpy dust with SMC-type extinction and scattering characteristics. The complete set of models is available in electronic form from the authors. This work has been supported by grants from NASA, which we acknowledge with gratitude.

Witt, A. N.; Gordon, K. D.

1999-05-01

18

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 ...

19

Diverse Galaxies: Clumpy Regions In The UVUDF at 0.5 ? z ? 1.5  

NASA Astrophysics Data System (ADS)

We present an investigation of clumpy galaxies using the deepest ultraviolet data in the Hubble Ultra Deep Field (HUDF) taken with Wide Field Camera 3 UVIS detector. We use 3 new post-flashed UV images taken with the F225W, F275W, and F336W filters. Here we present an analysis of all galaxies in the 0.5 to 1.5 redshift range. These galaxies show a variety of properties, with objects having just a single clump to galaxies littered with clumps. We perform an optical morphological study of ultraviolet-detected galaxies using a visual classification scheme similar to that employed by the Hubble CANDELS survey team. We find that the majority of the objects that are clumpy in the ultraviolet have optical morphologies that are disks, followed by irregulars. We measure galaxy luminosities in the rest-frame UV, clump sizes, and luminosities for each clump in 7 passbands from the UV to the optical. We find that the majority of these UV bright clumpy galaxies are classified as Scd and starburst spectral types and have clump sizes between 0.7 to 1.9 kpc. We quantify the contribution of the clumps to the global star formation rate of the galaxy.

Soto, Emmaris; de Mello, Duilia F.; Teplitz, Harry I.; Gardner, Jonathan P.; Bond, Nicholas A.; Rafelski, Marc; Ravindranath, Swara; Scarlata, Claudia; Codoreanu, Alex; Koekemoer, Anton M.; Kurczynski, Peter; Uvudf Team

2015-01-01

20

A Laboratory Investigation of Supersonic Clumpy Flows: Experimental Design and Theoretical Analysis  

E-print Network

We present a design for high energy density laboratory experiments studying the interaction of hypersonic shocks with a large number of inhomogeneities. These ``clumpy'' flows are relevant to a wide variety of astrophysical environments including the evolution of molecular clouds, outflows from young stars, Planetary Nebulae and Active Galactic Nuclei. The experiment consists of a strong shock (driven by a pulsed power machine or a high intensity laser) impinging on a region of randomly placed plastic rods. We discuss the goals of the specific design and how they are met by specific choices of target components. An adaptive mesh refinement hydrodynamic code is used to analyze the design and establish a predictive baseline for the experiments. The simulations confirm the effectiveness of the design in terms of articulating the differences between shocks propagating through smooth and clumpy environments. In particular, we find significant differences between the shock propagation speeds in a clumpy medium compared to a smooth one with the same average density. The simulation results are of general interest for foams in both inertial confinement fusion and laboratory astrophysics studies. Our results highlight the danger of using average properties of inhomogeneous astrophysical environments when comparing timescales for critical processes such as shock crossing and gravitational collapse times.

A. Y. Poludnenko; K. K. Dannenberg; R. P. Drake; A. Frank; J. Knauer; D. D. Meyerhofer; M. Furnish; J. R. Asay

2003-05-09

21

230 years of AGN monitoring: Frequency of cloud occultation events in AGN & constraints for clumpy torus models  

NASA Astrophysics Data System (ADS)

We systematically search for discrete absorption events in the vast archive of the Rossi X-ray Timing Explorer. This includes dozens of nearby type I and Compton-thin type II AGN and covers timescales from days to over a decade for individual objects. We are sensitive to discrete absorption events due to clouds of full-covering, neutral or mildly-ionized gas with columns 1022-25 cm-2 transiting the line of sight. We detect 13 eclipse events in 8 objects, roughly tripling the number of previously published events from this archive. Despite sensitivity to events with N H up to 1024-25 cm-2, we measured no Compton-thick eclipses in our sample. Peak column densities span 2.5-19 × 1022 cm-2. Event durations span hours to months. We infer the clouds distances from the black hole, assuming Keplerian motion, to span 0.2-80 × 104 Schwarzschild radii. We find no statistically significant difference between the individual cloud properties of type I and II objects. The presence of eclipses in both type Is and IIs argues against sharp-edged cloud distributions. The type II AGN show a level of ``base-line'' X-ray absorption that is consistent with being constant over timescales from 0.6 to 8.4 yr. This can either be explained by a homogeneous medium, or by X-ray-absorbing clouds that each have NH << 1022 cm-2. Considering the ``selection function'' of the monitoring, we derive the probability of cloud occultation events. Finally, we derive the first X-ray statistical constraints for clumpy-torus models.

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

2014-07-01

22

Common Cold  

NSDL National Science Digital Library

This Web site provides comprehensive information, selected by medical doctors, about the common cold. "The goal is to provide a framework for critical thinking which will allow informed decisions about medical care for the common cold." The section entitled Understanding Colds gives a detailed overview of how the cold virus invades the human body and how cold symptoms are caused. Information about preventing colds, and some of the complications that can occur are also included. The Special Features section includes one of the most interesting parts of the site -- Myths of the Common Cold. This site should be interesting to almost anyone, but perhaps more so for those of us who have recently had a cold.

23

Energy-Absorbing, Lightweight Wheels  

NASA Technical Reports Server (NTRS)

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.

Waydo, Peter

2003-01-01

24

Common cold  

MedlinePLUS

The common cold usually causes a runny nose, nasal congestion, and sneezing. You may also have a sore throat, cough, ... It is called the “common cold” for good reason. There are over one billion colds in the United States each year. You and your children will ...

25

The formation and evolution of clumpy galaxies from z=3 to z=0.5  

NASA Astrophysics Data System (ADS)

A common feature of star-forming galaxies at z>1 is the existence of giant star-forming clumps, which are fundamental to our understanding of the accretion history of galaxies, formation of bulges, and evolution of gas-rich disks. The origin and evolution of clumps are, however, still unclear. Using the deep and high-resolution optical (HST/ACS) and near--IR (HST/WFC3 IR) imaging data of CANDELS, we study the physical propeties of clumps in star-forming galaxies from z=3 to z=0.5. The CANDELS data enable us to resolve the sub-structures of galaxies to kiloparsec scale in the rest-frame UV and optical bands. In this talk, I will present our work on three aspects of the clumps: (1) the evolution of the fraction of star-forming galaxies with giant clumps from z=3 to z=0.5; (2) the physical properties (stellar mass, star formation rate, age, dust extinction, etc.) of clumps from z=3 to z=0.5; and (3) the connection between the clumpy appearance and the kinematics of settled (rotation dominated) and unsettled (velocity dispersion dominated) disks. The three aspects provide important clues of tracing the physical mechanisms that are responsible for transferring distant clumpy galaxies into disks and/or bulges seen in the local universe.

CANDELS

2015-01-01

26

Larson's scaling laws, and the gravitational instability of clumpy discs at high redshift  

NASA Astrophysics Data System (ADS)

Gravitational instabilities play a primary role in shaping the clumpy structure and powering the star formation activity of gas-rich high-redshift galaxies. Here, we analyse the stability of such systems, focusing on the size and mass ranges of unstable regions in the disc. Our analysis takes into account the mass-size and linewidth-size scaling relations observed in molecular gas, originally discovered by Larson. We show that such relations can have a strong impact on the size and mass of star-forming clumps, as well as on the stability properties of the disc at all observable scales, making the classical Toomre parameter a highly unreliable indicator of gravitational instability. For instance, a disc with Q = 1 can be far from marginal instability, while a disc with Q ? 1 can be marginally unstable. Our work raises an important caveat: if clumpy discs at high redshift have scale-dependent surface densities and velocity dispersions, as implied by the observed clump scaling relations, then we cannot thoroughly understand their stability and star formation properties unless we perform multiscale observations. This will soon be possible thanks to dedicated Atacama Large Millimeter/submillimeter Array surveys, which will explore the physical properties of supergiant molecular clouds at the peak of cosmic star formation and beyond.

Romeo, Alessandro B.; Agertz, Oscar

2014-08-01

27

Cold streams: detectability, relation to structure and characteristics  

NASA Astrophysics Data System (ADS)

Cold gas streaming along the dark-matter filaments of the cosmic web is predicted to be the major provider of resources for disc buildup and star formation in massive galaxies in the early universe. We use hydrodynamical simulations to study to what extent these cold streams are traceable in the extended circum-galactic environment of galaxies via Ly alpha emission, Ly alpha absorption and selected low ionisation metal absorption lines. We predict the strength of the absorption signal produced by the streams and find that it is consistent with observations in high redshift galaxies. The characteristics of the Ly alpha emission of our simulated galaxies are similar in luminosity, morphology and extent to the observed Ly alpha blobs, with distinct kinematic features. We analyse the characteristics of the cold streams in simulations and present scaling relations for the amount of infall, its velocity, distribution and its clumpiness and compare our findings with observations.

Goerdt, Tobias

2015-02-01

28

Fast cold gas in hot AGN outflows  

NASA Astrophysics Data System (ADS)

Observations of the emission from spatially extended cold gas around bright high-redshift quasars (QSOs) reveal surprisingly large velocity widths exceeding 2000 km s- 1, out to projected distances as large as 30 kpc. The high-velocity widths have been interpreted as the signature of powerful AGN-driven outflows. Naively, these findings appear in tension with hydrodynamic models in which AGN-driven outflows are energy-driven and thus very hot with typical temperatures T ? 106-7 K. Using the moving-mesh code AREPO, we perform `zoom-in' cosmological simulations of a z ˜ 6 QSO and its environment, following black hole growth and feedback via energy-driven outflows. In the simulations, the QSO host galaxy is surrounded by a clumpy circumgalactic medium pre-enriched with metals due to supernovae-driven galactic outflows. As a result, part of the AGN-driven hot outflowing gas can cool radiatively, leading to large amounts ( ? 109 M?) of cold gas comoving with the hot bipolar outflow. This results in velocity widths of spatially extended cold gas similar to those observed. We caution, however, that gas inflows, random motions in the deep potential well of the QSO host galaxy and cooling of supernovae-driven winds contribute significantly to the large velocity width of the cold gas in the simulations, complicating the interpretation of observational data.

Costa, Tiago; Sijacki, Debora; Haehnelt, Martin G.

2015-03-01

29

Methods for absorbing neutrons  

DOEpatents

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.

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

30

Externally tuned vibration absorber  

DOEpatents

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.

Vincent, Ronald J. (Latham, NY)

1987-09-22

31

Hot and Cold  

NSDL National Science Digital Library

In this activity, learners explore temperature changes from chemical reactions by mixing urea with water in one flask and mixing calcium chloride with water in another flask. They observe that the urea flask gets cold and the calcium chloride flask gets hot. The main idea is that some chemical processes release heat energy and are exothermic, while some chemical processes absorb heat energy and are endothermic. This activity is currently used in the Nature of Matter Unit in OMSI's Chemistry Lab. Cost estimates are per 100 learners.

Industry, Oregon M.

1997-01-01

32

Solar energy absorber  

Microsoft Academic Search

A solar energy absorber module is described comprising a molded substantially rigid top sheet of translucent plastic material and a molded substantially rigid bottom sheet of solar energy absorbing substantially opaque plastic material bonded together by circular bond indentations formed in each of the top sheet and the bottom sheet. The circular bond indentation on each sheet is spaced from

1988-01-01

33

Advanced neutron absorber materials  

DOEpatents

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.

Branagan, Daniel J. (Idaho Falls, ID); Smolik, Galen R. (Idaho Falls, ID)

2000-01-01

34

Multispectral metamaterial absorber.  

PubMed

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 ?m. This resonance is in addition to the THz metamaterial absorption resonance at 109 ?m (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. PMID:24690713

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

2014-03-01

35

Internal absorber solar collector  

DOEpatents

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.

Sletten, Carlyle J. (106 Nagog Hill Rd., Acton, MA 01720); Herskovitz, Sheldon B. (88 Hammond St., Acton, MA 01720); Holt, F. S. (46 Emerson Rd., Winchester, MA 01890); Sletten, E. J. (Chestnut Hill Rd. R.F.D. Rte. #4, Amherst, NH 03031)

1981-01-01

36

Lipid-absorbing Polymers  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

37

Electromagnetic power absorber  

NASA Technical Reports Server (NTRS)

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.

Iwasaki, R. S. (inventor)

1979-01-01

38

Absorbance modulation optical lithography  

E-print Network

In this thesis, the concept of absorbance-modulation optical lithography (AMOL) is described, and the feasibility experimentally verified. AMOL is an implementation of nodal lithography, which is not bounded by the diffraction ...

Tsai, Hsin-Yu Sidney

2007-01-01

39

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

NASA Astrophysics Data System (ADS)

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 H? 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 ?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.

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

40

Magnification Probability Distribution Functions of Standard Candles in a Clumpy Universe  

E-print Network

Lensing effects on light rays from point light sources, such like Type Ia supernovae, are simulated in a clumpy universe model. In our universe model, it is assumed that all matter in the universe takes the form of randomly distributed objects each of which has finite size and is transparent for light rays. Monte-Carlo simulations are performed for several lens models, and we compute probability distribution functions of magnification. In the case of the lens models that have a smooth density profile or the same degree of density concentration as the spherical NFW (Navarro-Frenk-White) lens model at the center, the so-called gamma distributions fit well the magnification probability distribution functions if the size of lenses is sufficiently larger than the Einstein radius. In contrast, the gamma distributions do not fit the magnification probability distribution functions in the case of the SIS (Singular Isothermal Sphere) lens model. We find, by using the power law cusp model, that the magnification probability distribution function is fitted well using the gamma distribution only when the slope of the central density profile is not very steep. These results suggest that we may obtain information about the slope of the central density profiles of dark matter halo from the lensing effect of Type Ia supernovae.

Chul-Moon Yoo; Hideki Ishihara; Ken-ichi Nakao; Hideyuki Tagoshi

2008-11-28

41

Infrared bolometers with silicon nitride micromesh absorbers  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

42

Shock Absorbing System  

NASA Technical Reports Server (NTRS)

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.

1982-01-01

43

Project COLD.  

ERIC Educational Resources Information Center

Describes Project COLD (Climate, Ocean, Land, Discovery) a scientific study of the Polar Regions, a collection of 35 modules used within the framework of existing subjects: oceanography, biology, geology, meterology, geography, social science. Includes a partial list of topics and one activity (geodesic dome) from a module. (Author/SK)

Kazanjian, Wendy C.

1982-01-01

44

Common Cold  

MedlinePLUS

... en español] National Library of Medicine, Medline Plus Common Cold Skip Content Marketing Share this: JavaScript is disabled in your browser. To view this content, please enable JavaScript and refresh the page. Click here for instructions on how to enable JavaScript in your browser. ...

45

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

SciTech Connect

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.

Menendez-Delmestre, Karin; Goncalves, Thiago S. [Observatorio do Valongo, Universidade Federal do Rio de Janeiro, Ladeira do Pedro Antonio 43, Saude, Rio de Janeiro, RJ 20080-090 (Brazil); Blain, Andrew W. [California Institute of Technology, MC 105-24, Pasadena, CA 91125 (United States); Swinbank, Mark; Smail, Ian [Institute for Computational Cosmology, Durham University, Durham DH1 3LE (United Kingdom); Ivison, Rob J. [UK Astronomy Technology Centre, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Chapman, Scott C., E-mail: kmd@astro.ufrj.br [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)

2013-04-20

46

Shock Absorbing Helmets  

NASA Technical Reports Server (NTRS)

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.

1978-01-01

47

Neutron Absorbing Alloys  

DOEpatents

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.

Mizia, Ronald E. (Idaho Falls, ID); Shaber, Eric L. (Idaho Falls, ID); DuPont, John N. (Whitehall, PA); Robino, Charles V. (Albuquerque, NM); Williams, David B. (Bethlehem, PA)

2004-05-04

48

Solar rocket absorber  

SciTech Connect

A solar rocket absorber of rhenium tubes is used to provide heated liquid hydrogen to a thruster. The rhenium tubes are wrapped in a closed shape having an opening for receiving solar radiation for heating the liquid propellant. The vessel of rhenium tubes is held by a carbon shell which is further encased in a reradiation shield to prevent heat loss.

Robinson, P. I.

1985-07-16

49

Imaging with cold neutrons  

NASA Astrophysics Data System (ADS)

Neutrons for imaging purposes are provided mainly from thermal beam lines at suitable facilities around the world. The access to cold neutrons is presently limited to very few places only. However, many challenging options for imaging with cold neutrons have been found out, given by the interaction behavior of the observed materials with neutrons in the cold energy range (3-10 Å). For absorbing materials, the interaction probability increases proportionally with the wavelength with the consequence of more contrast but less transmission with cold neutrons. Many materials are predominantly scattering neutrons, in particular most of crystalline structural materials. In these cases, cold neutrons play an important role by covering the energy range of the most important Bragg edges given by the lattice planes of the crystallites. This particular behavior can be used for at least two important aspects—choosing the right energy of the initial beam enables to have a material more or less transparent, and a direct macroscopic visualization of the crystalline structure and its change in a manufacturing process. Since 2006, PSI operates its second beam line for neutron imaging, where cold neutrons are provided from a liquid deuterium cold source (operated at 25 K). It has been designed to cover the most current aspects in neutron imaging research with the help of high flexibility. This has been done with changeable inlet apertures, a turbine based velocity selector, two beam positions and variable detector systems, satisfying the demands of the individual investigation. The most important detection system was found to be a micro-tomography system that enables studies in the presently best spatial resolution. In this case, the high contrast from the sample interaction process and the high detection probability for the cold neutrons combines in an ideal combination for the best possible performance. Recently, it was found out that the energy selective studies might become a research field in its own sing the Bragg edge behavior and its modification to contribute to material research by the direct visualization of textures and the observation of stress and strain. This topic is still in the beginning but has some important relevance for the design of future beam lines for imaging at the pulsed spallation sources. Considering the neutrons to be waves, the cold energy range is important to push and to investigate phase effects in detail with high spatial resolution. Although a lot of studies have been done in this respect previously, there is enough space to study refraction at the edges, diffraction and total reflection with the best possible accuracy, and to figure out when and why neutrons interfere. Phase contrast methods like grating interference methods have to be implemented as a user option, which enables one to define their future application range.

Lehmann, E. H.; Kaestner, A.; Josic, L.; Hartmann, S.; Mannes, D.

2011-09-01

50

Cold soybean management decision system based on JSP  

Microsoft Academic Search

In accordance with the requirements management of cold soybean growth characters integrated climatic conditions, soil fertility status of region, the laws of cold soybean absorbing nutrients, the soil nutrient supplying capacity and other various factors to set up models and rules. The system based on the object-oriented technology of JSP VB VC had some trials on middle plant part (Hailun),

Song Yihong; Yang Yushu; Li Xiao

2010-01-01

51

Chilling Out with Colds  

MedlinePLUS

... most common cold virus, but more than 200 viruses can cause colds. Because there are so many, ... to help you feel better. Take that, cold viruses! Continue How Kids Catch Colds Mucus (say: MYOO- ...

52

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

NASA Astrophysics Data System (ADS)

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 polarized, 11+/-3% and 12+/-3% (at Si2 and Si5 respectively) unresolved nucleus. Polarimetric modeling suggests that the MIR polarization arises from a synchrotron component. This result represents the most compelling MIR polarization detection of synchrotron radiation in Cygnus A.

Lopez Rodriguez, Enrique

53

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

NASA Technical Reports Server (NTRS)

Analysis of IUE high- and low-dispersion spectra of the young Herbig Ae star HR 5999 (HD 144668) covering 1978-1992 has 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. We also observe 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. 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 equal to or greater than 2 solar mass) PMS star. Recent IUE spectra show gas accreting toward the star with velocities as high as +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, upsilon sin i = 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, 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, and is not restricted to the clearing phase, since detectable amounts of accretion are present for stars with 0.5 less than t(sub age) less than 2.8 Myr. The implications for models of beta Pic and similar systems are briefly discussed.

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

1994-01-01

54

The quenching of star formation in accretion-driven clumpy turbulent tori of active galactic nuclei  

NASA Astrophysics Data System (ADS)

Galactic gas-gas collisions involving a turbulent multiphase interstellar medium (ISM) share common ISM properties: dense extraplanar gas visible in CO, large linewidths (?50 km s-1), strong mid-infrared H2 line emission, low star formation activity, and strong radio continuum emission. Gas-gas collisions can occur in the form of ram pressure stripping caused by the rapid motion of a spiral galaxy within the intracluster medium, galaxy head-on collisions, compression of the intragroup gas and/or galaxy ISM by an intruder galaxy which flies through the galaxy group at a high velocity, or external gas accretion on an existing gas torus in a galactic center. We suggest that the common theme of all these gas-gas interactions is adiabatic compression of the ISM leading to an increase of the turbulent velocity dispersion of the gas. The turbulent gas clouds are then overpressured and star formation is quenched. Within this scenario we developed a model for turbulent clumpy gas disks where the energy to drive turbulence is supplied by external infall or the gain of potential energy by radial gas accretion within the disk. The cloud size is determined by the size of a continuous (C-type) shock propagating in dense molecular clouds with a low ionization fraction at a given velocity dispersion. We give expressions for the expected volume and area filling factors, mass, density, column density, and velocity dispersion of the clouds. The latter is based on scaling relations of intermittent turbulence whose open parameters are estimated for the circumnuclear disk in the Galactic center. The properties of the model gas clouds (~0.1 pc, ~100 M?, ?v ? 6 km s-1) and the external mass accretion rate necessary for the quenching of the star formation rate due to adiabatic compression (? ~ 1-10 M? yr-1) are consistent with those derived from high-resolution H2 2.12 ?m line observations. Based on these findings, a scenario for the evolution of gas tori in galactic centers is proposed and the implications for star formation in the Galactic center are discussed.

Vollmer, B.; Davies, R. I.

2013-08-01

55

No More Active Galactic Nuclei in Clumpy Disks Than in Smooth Galaxies at z ~ 2 in CANDELS/3D-HST  

NASA Astrophysics Data System (ADS)

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. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA Inc, under NASA contract NAS 5-26555.

Trump, Jonathan R.; Barro, Guillermo; Juneau, Stéphanie; Weiner, Benjamin J.; Luo, Bin; Brammer, Gabriel B.; Bell, Eric F.; Brandt, W. N.; Dekel, Avishai; Guo, Yicheng; Hopkins, Philip F.; Koo, David C.; Kocevski, Dale D.; McIntosh, Daniel H.; Momcheva, Ivelina; Faber, S. M.; Ferguson, Henry C.; Grogin, Norman A.; Kartaltepe, Jeyhan; Koekemoer, Anton M.; Lotz, Jennifer; Maseda, Michael; Mozena, Mark; Nandra, Kirpal; Rosario, David J.; Zeimann, Gregory R.

2014-10-01

56

Corrosion resistant neutron absorbing coatings  

DOEpatents

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.

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

57

Lensing Effects on Gravitational Waves in a Clumpy Universe -Effects of Inhomogeneity on the Distance-Redshift Relation-  

E-print Network

The distance-redshift relation determined by means of gravitational waves in the clumpy universe is simulated numerically by taking into account the effects of gravitational lensing. It is assumed that all of the matter in the universe takes the form of randomly distributed point masses, each of which has the identical mass $M_L$. Calculations are carried out in two extreme cases: $\\lambda\\gg GM_L/c^2$ and $\\lambda\\ll GM_L/c^2$, where $\\lambda$ denotes the wavelength of gravitational waves. In the first case, the distance-redshift relation for the fully homogeneous and isotropic universe is reproduced with a small distance dispersion, whereas in the second case, the distance dispersion is larger. This result suggests that we might obtain information about the typical mass of lens objects through the distance-redshift relation gleaned through observation of gravitational waves of various wavelengths. In this paper, we show how to set limitations on the mass $M_L$ through the observation of gravitational waves in the clumpy universe model described above.

Chul-Moon Yoo; Ken-ichi Nakao; Hiroshi Kozaki; Ryuichi Takahashi

2006-04-06

58

Sensing with THz metamaterial absorbers  

E-print Network

Metamaterial perfect absorbers from microwaves to optical part of the electromagnetic spectrum has been intensely studied for its ability to absorb electromagnetic radiation. Perfect absorption of light by metamaterials have opened up new opportunities for application oriented functionalities such as efficient sensors and emitters. We present an absorber based sensing scheme at the terahertz frequencies and discuss optimized designs to achieve high frequency and amplitude sensitivities. The major advantage of a perfect metamaterial absorber as a sensor is the sensitive shift in the absorber resonance frequency along with the sharp change in the amplitude of the resonance due to strong interaction of the analyte with the electric and the magnetic fields at resonant perfect absorption frequency. We compare the sensing performance of the perfect metamaterial absorber with its complementary structural design and planar metasurface with identical structure. The best FoM values obtained for the absorber sensor here...

Cong, Longqing

2014-01-01

59

Absorber coatings' degradation  

SciTech Connect

This report is intended to document some of the Los Alamos efforts that have been carried out under the Department of Energy (DOE) Active Heating and Cooling Materials Reliability, Maintainability, and Exposure Testing program. Funding for these activities is obtained directly from DOE although they represent a variety of projects and coordination with other agencies. Major limitations to the use of solar energy are the uncertain reliability and lifetimes of solar systems. This program is aimed at determining material operating limitations, durabilities, and failure modes such that materials improvements can be made and lifetimes can be extended. Although many active and passive materials and systems are being studied at Los Alamos, this paper will concentrate on absorber coatings and degradation of these coatings.

Moore, S.W.

1984-01-01

60

Cold knife cone biopsy  

MedlinePLUS

A cold knife cone biopsy (conization) is surgery to remove a sample of abnormal tissue from the cervix. The cervix is ... Cold knife cone biopsy is done to detect cervical cancer or early changes that lead to cancer. A cold ...

61

Bronchitis (Chest Cold)  

MedlinePLUS

... Antibiotic Use Respiratory Illnesses Sinus Infection Sore Throat Common Cold and Runny Nose Ear Infections Bronchitis (Chest Cold) ... Tips Appropriate Treatment Summary Cough Illness/Bronchitis The Common Cold Otitis Media Pharyngitis: Treat Only Proven GAS Online ...

62

Electrochemically regenerable carbon dioxide absorber  

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

63

Broadband patterned magnetic microwave absorber  

NASA Astrophysics Data System (ADS)

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 ?/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.

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

2014-07-01

64

Cold Atoms  

NASA Astrophysics Data System (ADS)

This chapter and the following one address collective effects of quantum particles, that is, the effects which are observed when we put together a large number of identical particles, for example, electrons, helium-4 or rubidium-85 atoms. We shall see that quantum particles can be classified into two categories, bosons and fermions, whose collective behavior is radically different. Bosons have a tendency to pile up in the same quantum state, while fermions have a tendency to avoid each other. We say that bosons and fermions obey two different quantum statistics, the Bose-Einstein and the Fermi-Dirac statistics, respectively. Temperature is a collective effect, and in Section 5.1 we shall explain the concept of absolute temperature and its relation to the average kinetic energy of molecules. We shall describe in Section 5.2 how we can cool atoms down thanks to the Doppler effect, and explain how cold atoms can be used to improve the accuracy of atomic clocks by a factor of about 100. The effects of quantum statistics are prominent at low temperatures, and atom cooling will be used to obtain Bose-Einstein condensates at low enough temperatures, when the atoms are bosons.

Bellac, Michel Le

2014-11-01

65

Improvement Of The Helmholtz Absorber  

NASA Technical Reports Server (NTRS)

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.

Morrow, Duane L.

1992-01-01

66

HYPOTHERMIA Surviving the Cold  

E-print Network

), and fatigue are some of the main factors that can contribute to hypothermia. · Cold is the most common causeHYPOTHERMIA Surviving the Cold www.WorkSafebc.com #12;About the WCB Preventing on-the-job injury-HELP) toll-free in British Columbia. #12;1 Introduction Working in a cold environment ­ whether it be cold

Machel, Hans

67

Facts about the Common Cold  

MedlinePLUS

... Disease > Influenza > In-Depth-Resources Facts About the Common Cold What Is a Cold? Colds are minor infections ... for 10 to 40 percent of colds. Other common cold viruses include coronavirus and respiratory syncytial virus (RSV). ...

68

Chaotic cold accretion on to black holes  

NASA Astrophysics Data System (ADS)

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 many systems, such as hot galactic haloes, groups and clusters. In this mode, the black hole can quickly react to the state of the entire host galaxy, leading to efficient self-regulated AGN feedback and the symbiotic Magorrian relation. Chaotic accretion can generate high-velocity clouds, likely leading to strong variations in the AGN luminosity, and the deflection or mass-loading of jets. During phases of overheating, the hot mode becomes the single channel of accretion, though strongly suppressed by turbulence. High-resolution data could determine the current mode of accretion: assuming quiescent feedback, the cold mode results in a quasi-flat-temperature core as opposed to the cuspy profile of the hot mode.

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

2013-07-01

69

Leaf absorbance and photosynthesis  

NASA Technical Reports Server (NTRS)

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.

Schurer, Kees

1994-01-01

70

Cold Signaling and Cold Response in Plants  

PubMed Central

Plants are constantly exposed to a variety of environmental stresses. Freezing or extremely low temperature constitutes a key factor influencing plant growth, development and crop productivity. Plants have evolved a mechanism to enhance tolerance to freezing during exposure to periods of low, but non-freezing temperatures. This phenomenon is called cold acclimation. During cold acclimation, plants develop several mechanisms to minimize potential damages caused by low temperature. Cold response is highly complex process that involves an array of physiological and biochemical modifications. Furthermore, alterations of the expression patterns of many genes, proteins and metabolites in response to cold stress have been reported. Recent studies demonstrate that post-transcriptional and post-translational regulations play a role in the regulation of cold signaling. In this review article, recent advances in cold stress signaling and tolerance are highlighted. PMID:23466881

Miura, Kenji; Furumoto, Tsuyoshi

2013-01-01

71

thin films as absorber  

NASA Astrophysics Data System (ADS)

Photovoltaic structures were prepared using AgSb(S x Se1- x )2 as absorber and CdS as window layer at various conditions via a hybrid technique of chemical bath deposition and thermal evaporation followed by heat treatments. Silver antimony sulfo selenide thin films [AgSb(S x Se1- x )2] were prepared by heating multilayers of sequentially deposited Sb2S3/Ag dipped in Na2SeSO3 solution, glass/Sb2S3/Ag/Se. For this, Sb2S3 thin films were deposited from a chemical bath containing SbCl3 and Na2S2O3. Then, Ag thin films were thermally evaporated on glass/Sb2S3, followed by selenization by dipping in an acidic solution of Na2SeSO3. The duration of dipping was varied as 3, 4 and 5 h. Two different heat treatments, one at 350 °C for 20 min in vacuum followed by a post-heat treatment at 325 °C for 2 h in Ar, and the other at 350 °C for 1 h in Ar, were applied to the multilayers of different configurations. X-ray diffraction results showed the formation of AgSb(S x Se1- x )2 thin films as the primary phase and AgSb(S,Se)2 and Sb2S3 as secondary phases. Morphology and elemental detection were done by scanning electron microscopy and energy dispersive X-ray analysis. X-ray photoelectron spectroscopic studies showed the depthwise composition of the films. Optical properties were determined by UV-vis-IR transmittance and reflection spectral analysis. AgSb(S x Se1- x )2 formed at different conditions was incorporated in PV structures glass/FTO/CdS/AgSb(S x Se1- x )2/C/Ag. Chemically deposited post-annealed CdS thin films of various thicknesses were used as window layer. J- V characteristics of the cells were measured under dark and AM1.5 illumination. Analysis of the J- V characteristics resulted in the best solar cell parameters of V oc = 520 mV, J sc = 9.70 mA cm-2, FF = 0.50 and ? = 2.7 %.

González, J. O.; Shaji, S.; Avellaneda, D.; Castillo, G. A.; Das Roy, T. K.; Krishnan, B.

2014-09-01

72

An introduction to absorbent dressings.  

PubMed

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. PMID:25478853

Jones, Menna Lloyd

2014-12-01

73

Absorbable Biologically Based Internal Fixation.  

PubMed

Absorbable fixation devices have developed since first being introduced. Current products are manufactured for greater strength and stiffness and slower break down. Absorbable devices for internal fixation should not be used when fracture fragments exclusively depend on screws for bearing direct load; rather, they are preferred for maintaining adequate compression and preventing displacement when some intrinsic stability exists between bones. The main advantage of absorbable internal fixation devices is their flexibility of use. A newer generation synthesized from silk has emerged and may help to overcome current limitations and address a broader range of fixation needs. PMID:25440418

Ibrahim, Ahmed M S; Koolen, Pieter G L; Kim, Kuylhee; Perrone, Gabe S; Kaplan, David L; Lin, Samuel J

2015-01-01

74

Absorption of protein, fatty acids and minerals in young turkeys under heat and cold stress  

Microsoft Academic Search

1. Absorption of protein, fatty acids, calcium, phosphate and potassium by young turkeys maintained at thermoneutral (24 °C), hot (35 °C) and cold (8 °C) conditions was examined.2. Non?acclimatised, heat?stressed birds absorbed less potassium and phosphate, whereas absorption of nitrogen, fatty acids and calcium was not altered, as compared with birds at 24 °C. Non?acclimatised, cold?stressed birds absorbed less calcium

D. Wolfenson; D. Sklan; Y. Graber; O. Kedar; I. Bengal; S. Hurwitz

1987-01-01

75

Massive Stellar Clusters ASP Conference Series 2000 A.Lançon and C.M.Boily, eds. Patterns of Super Star Cluster Formation in ‘Clumpy  

E-print Network

We present preliminary results from a Hubble Space Telescope (HST) WFPC2 investigation of spatial and temporal distributions of star clusters in the clumpy irregular galaxy NGC 7673 and the starburst spirals NGC 3310 and Haro 1. We compare the spectral energy distributions of star clusters in the large clumps in NGC 7673 to model calculations of stellar clusters of various ages. We also propose that the presence of super star clusters in clumps seems to be a feature of intense starbursts. 1.

Starburst Galaxies; J. S. Gallagher; N. L. Homeier; C. J. Conselice

2000-01-01

76

Packed Alumina Absorbs Hypergolic Vapors  

NASA Technical Reports Server (NTRS)

Beds of activated alumina effective as filters to remove hypergolic vapors from gas streams. Beds absorb such substances as nitrogen oxides and hydrazines and may also absorb acetylene, ethylene, hydrogen sulfide, benzene, butadiene, butene, styrene, toluene, and xoylene. Bed has no moving parts such as pumps, blowers and mixers. Reliable and energy-conservative. Bed readily adapted to any size from small portable units for use where little vapor release is expected to large stationary units for extensive transfer operations.

Thomas, J. J.; Mauro, D. M.

1984-01-01

77

Countercurrent flow absorber and desorber  

DOEpatents

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.

Wilkinson, William H. (Columbus, OH)

1984-01-01

78

Perfect selective metamaterial solar absorbers.  

PubMed

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. PMID:24514927

Wang, Hao; Wang, Liping

2013-11-01

79

Cold Stress and the Cold Pressor Test  

ERIC Educational Resources Information Center

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…

Silverthorn, Dee U.; Michael, Joel

2013-01-01

80

Vitamin C and colds  

MedlinePLUS

... popular belief that vitamin C can cure the common cold , the scientific evidence for this is conflicting. Large ... B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev . 2007 Jul 18;(3): ...

81

Mushroom plasmonic metamaterial infrared absorbers  

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

82

Nonventing, Regenerable, Lightweight Heat Absorber  

NASA Technical Reports Server (NTRS)

A lightweight, regenerable heat absorber (RHA), developed for rejecting metabolic heat from a space suit, may also be useful on Earth for short-term cooling of heavy protective garments. Unlike prior space-suit-cooling systems, a system that includes this RHA does not vent water. The closed system contains water reservoirs, tubes through which water is circulated to absorb heat, an evaporator, and an absorber/radiator. The radiator includes a solution of LiCl contained in a porous material in titanium tubes. The evaporator cools water that circulates through a liquid-cooled garment. Water vapor produced in the evaporator enters the radiator tubes where it is absorbed into the LiCl solution, releasing heat. Much of the heat of absorption is rejected to the environment via the radiator. After use, the RHA is regenerated by heating it to a temperature of 100 C for about 2 hours to drive the absorbed water back to the evaporator. A system including a prototype of the RHA was found to be capable of maintaining a temperature of 20 C while removing heat at a rate of 200 W for 6 hours.

Izenson, Michael G.; Chen, Weibo

2008-01-01

83

The X-Ray Warm Absorber in NGC 3516  

NASA Technical Reports Server (NTRS)

The Seyfert 1 galaxy, NGC 3516 has been the subject of many absorption line studies at both ultra-violet and X-ray wavelengths. In the UV, strong, broad, variable associated metal line absorption with velocity width approximately 2000 km s(exp -1) is thought to originate in gas with N(sub H)greater than or approximately 10(exp 10)cm (exp -2) lying between 0.01 and 9 pc from the central active nucleus. The Ginga X-ray data are consistent with several possibilities: a warm absorber and a cold absorber combined either with partial covering or an unusually strong reflection spectrum. We present ROSAT observations of NGC 3516 which show a strong detection of a warm absorber dominated by a blend of 0 VII/O VIII edges at approximately 0.8 keV with N(sub H) approximately 7x10(exp 21)cm(exp -2), and U:8-12. We argue that NGC 3516 contains an outflowing 'XUV' absorber showing the presence of X-ray absorption edges which are consistent with the presence of broad absorption lines in the old IUE spectra and their disappearance in the new UV observations. Our dynamical model suggests that the O VII absorption edge will continue to weaken compared to the O VIII edge, an easily testable prediction with future missions like AXAF. Eventually the source would be transparent to the X-rays unless a new absorption system is produced.

Mathur, Smita; Wilkes, Belinda; Aldcroft, Thomas

1997-01-01

84

Damage tolerant light absorbing material  

DOEpatents

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.

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

1993-09-07

85

Damage tolerant light absorbing material  

DOEpatents

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.

Lauf, Robert J. (Oak Ridge, TN); Hamby, Jr., Clyde (Harriman, TN); Akerman, M. Alfred (Knoxville, TN); Seals, Roland D. (Oak Ridge, TN)

1993-01-01

86

Waveform-dependent absorbing metasurfaces  

E-print Network

We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high power pulses but not for high power continuous waves (CWs), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e. CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

Wakatsuchi, Hiroki; Rushton, Jeremiah J; Sievenpiper, Daniel F

2014-01-01

87

Waveform-Dependent Absorbing Metasurfaces  

NASA Astrophysics Data System (ADS)

We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high-power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high-power pulses but not for high-power continuous waves (CW’s), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e., CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

Wakatsuchi, Hiroki; Kim, Sanghoon; Rushton, Jeremiah J.; Sievenpiper, Daniel F.

2013-12-01

88

Waveform-dependent absorbing metasurfaces.  

PubMed

We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high-power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high-power pulses but not for high-power continuous waves (CW's), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e., CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications. PMID:24483674

Wakatsuchi, Hiroki; Kim, Sanghoon; Rushton, Jeremiah J; Sievenpiper, Daniel F

2013-12-13

89

Systems Analysis Of Absorbing Media  

NASA Astrophysics Data System (ADS)

A complete treatment of the characteristic admittance-matrix representation of multilayer thin-film systems with absorbing media is presented. The algorithm from the systems' analysis is implemented on an IBM microcomputer and some examples of filter design calculations are presented. Relevant source code in IBM ADVANCED BASIC interpreter are also included.

Lim, Y. K.; Seeley, J. S.

1986-10-01

90

Polyneutrons as agents for cold nuclear reactions  

SciTech Connect

In this paper new nuclear reactions are described where polyneutrons exchange neutron pairs with charged nuclides, liberating substantial energy with only minor production of neutrons and tritium. It is postulated that polyneutrons are bound in a totally paired collective phase analogous to the Bardeen-Cooper-Schrieffer superconducting phase, that massive precursor hydrogen nuclides are bound in the same collective phase, and the polyneutrons are generated from precursor hydrogen by reaction with neutrons. The concentration and disposition of precursor hydrogen, of lithium, and of neutron-moderating and neutron-absorbing materials in the reactor environment emerge as key variables in cold nuclear reaction processes.

Fisher, J.C. (Thomas Paine Associates, Carpinteria, CA (United States))

1992-12-01

91

Cold stress and the cold pressor test.  

PubMed

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. PMID:23471256

Silverthorn, Dee U; Michael, Joel

2013-03-01

92

Cold Air Damming  

NSDL National Science Digital Library

Cold Air Damming is part of the Mesoscale Meteorology Primer series. This module first presents a Navy forecast scenario prior to the development of a major cold air damming (CAD) event along the east slopes of the Appalachian Mountains. Then, from a conceptual standpoint, the classic CAD scenario is described in detail, both from an observational and modeling standpoint.

2014-09-14

93

Photochemistry in the Inner Layers of Clumpy Circumstellar Envelopes: Formation of Water in C-rich Objects and of C-bearing Molecules in O-rich Objects  

NASA Astrophysics Data System (ADS)

A mechanism based on the penetration of interstellar ultraviolet photons into the inner layers of clumpy circumstellar envelopes (CSEs) around asymptotic giant branch stars is proposed to explain the non-equilibrium chemistry observed in such objects. We show through a simple modeling approach that in CSEs with a certain degree of clumpiness or with moderately low mass loss rates (a few 10-7 M sun yr-1) a photochemistry can take place in the warm and dense inner layers, inducing important changes in the chemical composition. In carbon-rich objects water vapor and ammonia would be formed with abundances of 10-8-10-6 relative to H2, while in oxygen-rich envelopes ammonia and carbon-bearing molecules such as HCN and CS would form with abundances of 10-9-10-7 relative to H2. The proposed mechanism would explain the recent observation of warm water vapor in the carbon-rich envelope IRC+10216 with the Herschel Space Observatory and predict that H2O should be detectable in other carbon-rich objects.

Agúndez, Marcelino; Cernicharo, José; Guélin, Michel

2010-12-01

94

Improving the laboratory monitoring of absorbent oil  

SciTech Connect

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.

V.S. Shved; S.S. Sychev; I.V. Safina; S.A. Klykov [OAO Koks, Kemerovo (Russian Federation)

2009-05-15

95

Embedded absorbers for helicopter rotor lag damping  

Microsoft Academic Search

Radial and chordwise damped vibration absorbers embedded in the rotor blade are compared for rotor lag damping augmentation. Results show that the radial absorber is more effective in transferring damping to the rotor blade lag mode. The chordwise absorber needs to be at a more outboard location and have a larger mass to introduce levels of lag damping comparable to

Lynn Byers; Farhan Gandhi

2009-01-01

96

Embedded absorbers for helicopter rotor lag damping  

NASA Astrophysics Data System (ADS)

Radial and chordwise damped vibration absorbers embedded in the rotor blade are compared for rotor lag damping augmentation. Results show that the radial absorber is more effective in transferring damping to the rotor blade lag mode. The chordwise absorber needs to be at a more outboard location and have a larger mass to introduce levels of lag damping comparable to that introduced by the radial absorber. The 1/rev amplitude of a chordwise absorber at the blade tip, per degree of blade lead-lag motion in forward flight, is of the order of 35% of the blade chord, and such a stroke might be difficult to accommodate. The 1/rev amplitude of a radial absorber at 70% span (having significantly lower mass than the chordwise absorber and producing comparable lag damping) is of the order of 4% of the rotor blade span. The static displacement of the radial absorber under centrifugal load needs to be limited using a frequency-dependent (high static stiffness, low dynamic stiffness) or nonlinear spring. The chordwise absorber can also undergo a large static displacement under the chordwise component of the centrifugal load if there is an offset from the feather axis, and this would again have to be limited using a strategy such as a frequency-dependent spring. Significant advantages of the radial absorber are—higher lag damping, lower absorber mass, space for absorber mass travel, and no chordwise travel of blade center of gravity reducing susceptibility to aeroelastic instability and dynamic pitch-link loads.

Byers, Lynn; Gandhi, Farhan

2009-09-01

97

Warm absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies: I. A global view and frequency of occurrence of warm absorbers  

E-print Network

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. Our goal is to characterise the warm absorber (WA) properties along the line-of-sight to the active nucleus. We significantly detect WAs in $65\\%$ of the sample sources. Our results are consistent with WAs being present in at least half of the Seyfert galaxies in the nearby Universe, in agreement with previous estimates . We find a gap in the distribution of the ionisation parameter in the range $0.5warm absorber flow is probably constituted by a clumpy distribution of discrete clouds rather than a continuous medium. The distribution of the WA column densities for the sources with broad Fe K$\\alpha$ lines are similar to those sources which do not have broadened emission l...

Laha, Sibasish; Dewangan, Gulab C; Chakravorty, Susmita; Kembhavi, Ajit K

2014-01-01

98

The small covering factor of cold accretion streams  

NASA Astrophysics Data System (ADS)

Theoretical models of galaxy formation predict that galaxies acquire most of their baryons via cold mode accretion. Observations of high-redshift galaxies, while showing ubiquitous outflows, have so far not revealed convincing traces of the predicted cold streams, which has been interpreted as a challenge for the current models. Using high-resolution, zoom-in smooth particle hydrodynamics simulations of Lyman break galaxy (LBG) haloes combined with ionizing radiative transfer, we quantify the covering factor of the cold streams at z= 2-4. We focus specifically on Lyman limit systems (LLSs) and damped Ly? absorbers (DLAs), which can be probed by absorption spectroscopy using a background galaxy or quasar sightline, and which are closely related to low-ionization metal absorbers. We show that the covering factor of these systems is relatively small and decreases with time. At z= 2, the covering factor of DLAs within the virial radius of the simulated galaxies is ˜3 per cent (˜1 per cent within twice this projected distance), and arises principally from the galaxy itself. The corresponding values for LLSs are ˜10 and 4 per cent. Because of their small covering factor compared to the order unity covering fraction expected for galactic winds, the cold streams are naturally dominated by outflows in stacked spectra. We conclude that the existing observations are consistent with the predictions of cold mode accretion, and outline promising kinematic and chemical diagnostics to separate out the signatures of galactic accretion and feedback.

Faucher-Giguère, Claude-André; Kereš, Dušan

2011-03-01

99

Porcelain enamel neutron absorbing material  

DOEpatents

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.

Iverson, D.C.

1987-11-20

100

Porcelain enamel neutron absorbing material  

DOEpatents

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.

Iverson, Daniel C. (Aiken, SC)

1990-01-01

101

Graphene saturable absorbers for VECSELs  

NASA Astrophysics Data System (ADS)

We report mode-locking of an optically pumped VECSEL using a graphene-based saturable absorber mirror (GSAM). Self-starting and stable modelocked operation is demonstrated with 473 fs pulses at 1.5 GHz repetition rate and 949 nm center wavelength. Wavelength tuning is achieved over a 46 nm bandwidth. We discuss the mirror design, the fabrication of the GSAMs, and give an outlook on further optimization of the design, including dielectric top coatings to protect the graphene and to increase the flexibility in the design.

Wittwer, V. J.; Zaugg, C. A.; Sun, Z.; Popa, D.; Milana, S.; Kulmala, T. S.; Sundaram, R. S.; Mangold, M.; Golling, M.; Lee, Y.; Ahn, J. H.; Keller, U.; Ferrari, A. C.

2014-03-01

102

The Common Cold  

NSDL National Science Digital Library

When winter rolls around and we begin to spend more time indoors, the common cold becomes an unfortunate reality for many of us. But for something as common as the cold, misconceptions about it are remarkably common as well. The following collection of Web sites provides an in-depth look at the cold and the cold virus.The first site (1) comes from the Common Cold Care Center of Cardiff University in Wales, and offers a thorough and highly readable introduction to the common cold, including sections on conventional and alternative cold medications. Readers can brush up on their basic virology with the next Web site from HowStuffWorks to get a clear, general idea of how the cold virus infects the body (2). This site also explains why antibiotics have no effect on a virus, and includes numerous hypertext links to related HowStuffWorks Web pages. KidsHealth for Parents, a service of the Nemours Foundation, provides a straightforward guide to the symptoms of cold vs. flu, while also offering information on flu treatment options (3). The next Web site, from University of Guelph, contains an easy-to-understand comparison of bacteria and viruses (4). Readers can learn more about rhinoviruses, the family of viruses which account for about one-third of all colds, in the following Web site from the University of South Carolina's Microbiology and Immunology Online (5). The next Web site offers visitors a close-up look at human rhinovirus 14 with over a dozen 3-D images and movies from the University of Wisconsin-Madison Bock Laboratory (6). The following site describes the findings, as detailed in the Proceedings of the National Academy of Sciences, of a Purdue University research team that has analyzed on an atomic scale the structure of the cellular receptor that binds cold-causing viruses (7). And finally, find out about common cold clinical trials with ClinicalTrial.gov, a service of the National Institutes of Health (8).

Sohmer, Rachel.

2003-01-01

103

Extragalactic H_2O masers and X-ray absorbing column densities  

E-print Network

Having conducted a search for the 22 GHz water vapor line towards galaxies with nuclear activity, large nuclear column densities or high infrared luminosities, we present H_2O spectra for NGC2273, UGC5101 and NGC3393 with isotropic luminosities of 7, 1500, and 400 L_sun. The H_2O maser in UGC5101 is by far the most luminous yet found in an ultraluminous infrared galaxy. NGC3393 reveals the classic spectrum of a `disk maser', represented by three distinct groups of Doppler components. As in all other known cases except NGC4258, the rotation velocity of the putative masing disk is well below 1000 km/s. Based on the literature and archive data, X-ray absorbing column densities are compiled for the 64 galaxies with reported maser sources beyond the Magellanic Clouds. For NGC2782 and NGC5728, we present Chandra archive data that indicate the presence of an active galactic nucleus in both galaxies. The correlation between absorbing column and H_2O emission is analyzed. There is a striking difference between kilo- and megamasers with megamasers being associated with higher column densities. All kilomasers (L_H_2O columns are 10^23 cm^-2) active galactic nuclei. These values are not larger but consistent with those from samples of Seyfert 2 galaxies not selected on the basis of maser emission. The similarity in column densities can be explained by small deviations in position between maser spots and nuclear X-ray source and a high degree of clumpiness in the circumnuclear interstellar medium.

J. S. Zhang; C. Henkel; M. Kadler; L. J. Greenhill; N. Nagar; A. S. Wilson; J. A. Braatz

2005-12-17

104

21 CFR 886.3300 - Absorbable implant (scleral buckling method).  

Code of Federal Regulations, 2010 CFR

...false Absorbable implant (scleral buckling method). 886.3300 Section...3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a device intended...

2010-04-01

105

Coping with Colds  

MedlinePLUS

... by viruses called rhinoviruses that are in invisible droplets in the air you breathe or on things ... Continue Catching Colds Rhinoviruses can stay alive as droplets in the air or on surfaces for as ...

106

Teaching in a Cold Environment.  

ERIC Educational Resources Information Center

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)

Ewert, Alan

1979-01-01

107

Teaching in a Cold Environment.  

ERIC Educational Resources Information Center

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:…

Ewert, Alan

108

Numerical simulations of quasar absorbers  

E-print Network

The physical state of the intergalactic medium can be probed in great detail with the intervening absorption systems seen in quasar spectra. The properties of the Hydrogen absorbers depend on many cosmological parameters, such as the matter-power spectrum, reionisation history, ionising background and the nature of the dark matter. The spectra also contain metal lines, which can be used to constrain the star formation history and the feedback processes acting in large and small galaxies. Simulations have been instrumental in investigating to what extent these parameters can be unambiguously constrained with current and future data. This paper is meant as an introduction to this subject, and reviews techniques and methods for simulating the intergalactic medium.

Tom Theuns

2005-07-25

109

Hydrodynamic simulations of the interaction of supernova shock waves with a clumpy environment: the case of the RX J0852.0-4622 (Vela Jr) supernova remnant  

NASA Astrophysics Data System (ADS)

Observations in all electromagnetic bands show that many supernova remnants (SNRs) have a very aspherical shape. This can be the result of asymmetries in the supernova explosion or a clumpy circumstellar medium. We study the generation of inhomogeneities and the mixing of elements arising from these two sources in multidimensional hydrodynamic simulations of the propagation of a supernova blast wave into a cloudy environment. We model a specific SNR, Vela Jr (RX J0852.0-4622). By comparing our results with recent observations, we can constrain the properties of the explosion. We find that a very energetic explosion of several 1051 erg occurring roughly about 800 years ago is consistent with the shape and emission of the SNR, as well as a supernova with an energy closer to the canonical value of 1051 erg a few thousand years ago.

Obergaulinger, M.; Iyudin, A. F.; Müller, E.; Smoot, G. F.

2014-01-01

110

Absorption of protein, fatty acids and minerals in young turkeys under heat and cold stress.  

PubMed

1. Absorption of protein, fatty acids, calcium, phosphate and potassium by young turkeys maintained at thermoneutral (24 degrees C), hot (35 degrees C) and cold (8 degrees C) conditions was examined. 2. Non-acclimatised, heat-stressed birds absorbed less potassium and phosphate, whereas absorption of nitrogen, fatty acids and calcium was not altered, as compared with birds at 24 degrees C. Non-acclimatised, cold-stressed birds absorbed less calcium than control birds and more nitrogen than non-acclimatised, heat-stressed birds. 3. Heat acclimatization might reduce the adverse effect of heat stress on potassium and phosphate absorption. PMID:3446341

Wolfenson, D; Sklan, D; Graber, Y; Kedar, O; Bengal, I; Hurwitz, S

1987-12-01

111

Magnetic field effects on microwave absorbing materials  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

112

An omnidirectional electromagnetic absorber made of metamaterials  

NASA Astrophysics Data System (ADS)

In a recent theoretical work by Narimanov and Kildishev (2009 Appl. Phys. Lett. 95 041106) an optical omnidirectional light absorber based on metamaterials was proposed, in which theoretical analysis and numerical simulations showed that all optical waves hitting the absorber are trapped and absorbed. Here we report the first experimental demonstration of an omnidirectional electromagnetic absorber in the microwave frequency. The proposed device is composed of non-resonant and resonant metamaterial structures, which can trap and absorb electromagnetic waves coming from all directions spirally inwards without any reflections due to the local control of electromagnetic fields. It is shown that the absorption rate can reach 99 per cent in the microwave frequency. The all-directional full absorption property makes the device behave like an 'electromagnetic black body', and the wave trapping and absorbing properties simulate, to some extent, an 'electromagnetic black hole.' We expect that such a device could be used as a thermal emitting source and to harvest electromagnetic waves.

Cheng, Qiang; Cui, Tie Jun; Jiang, Wei Xiang; Cai, Ben Geng

2010-06-01

113

Dusty Structure Around Type-I Active Galactic Nuclei: Clumpy Torus Narrow-line Region and Near-nucleus Hot Dust  

NASA Astrophysics Data System (ADS)

We fitted Spitzer/IRS ~ 2-35 ?m spectra of 26 luminous quasi-stellar objects in an attempt to define the main emission components. Our model has three major components: a clumpy torus, dusty narrow-line region (NLR) clouds, and a blackbody-like dust. The models utilize the clumpy torus of Nenkova et al. and are the first to allow its consistent check in type-I active galactic nuclei (AGNs). Single torus models and combined torus-NLR models fail to fit the spectra of most sources, but three-component models adequately fit the spectra of all sources. We present torus inclination, cloud distribution, covering factor, and torus mass for all sources and compare them with bolometric luminosity, black hole mass, and accretion rate. The torus mass is found to be correlated with the bolometric luminosity of the sources. Torus-covering factor may also be (anti-)correlated, if some possibly anomalous points are omitted. We find that a substantial amount of the ~2-7 ?m radiation originates from a hot dust component, which is likely situated in the innermost part of the torus. The luminosity radiated by this component and its covering factor are comparable to those of the torus. We quantify the emission by the NLR clouds and estimate their distance from the center. The distances are ~700 times larger than the dust sublimation radius, and the NLR-covering factor is about 0.07. The total covering factor by all components is in good agreement with the known AGN type-I:type-II ratio.

Mor, Rivay; Netzer, Hagai; Elitzur, Moshe

2009-11-01

114

Photoacoustic cavitation in spherical and cylindrical absorbers  

Microsoft Academic Search

.   Photomechanical damage in absorbing regions or particles surrounded by a non-absorbing medium is investigated experimentally\\u000a and theoretically. The damage mechanism is based on the generation of thermoelastic pressure by absorption of pulsed laser\\u000a radiation under conditions of stress confinement. Principles of photoacoustic sound generation predict that the acoustic wave\\u000a generated in a finite-size absorbing region must contain both compressive

G. Paltauf; H. Schmidt-Kloiber

1999-01-01

115

Absorbent product and articles made therefrom  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

116

Advanced Reflector and Absorber Materials (Fact Sheet)  

SciTech Connect

Fact sheet describing NREL CSP Program capabilities in the area of advanced reflector and absorber materials: evaluating performance, determining degradation rates and lifetime, and developing new coatings.

Not Available

2010-08-01

117

Antioxidant properties of cold-pressed black caraway, carrot, cranberry, and hemp seed oils  

Microsoft Academic Search

Cold-pressed black caraway, carrot, cranberry, and hemp seed oils were extracted with methanol and evaluated for radical-scavenging activities against ABTS+ and DPPH, chelating activity, oxygen radical absorbing capacity (ORAC), and total phenolic contents (TPC). All the oil extracts had significant antioxidant activities. The ORAC value ranged from 28 to 220 ?mol TE\\/g oil for the cold-pressed hemp, carrot, and black

Liangli Lucy Yu; Kequan Kevin Zhou; John Parry

2005-01-01

118

Monogroove cold plate  

NASA Technical Reports Server (NTRS)

The coolant fluid evaporated in a compact heat absorbing panel utilizing monogroove heat pipes in a pumped two-phase system is replenished through a liquid inlet control valve under the control of an ultrasonic liquid presence detector which is connected to the panel. The detector maintains the desired liquid quantity in the panel's liquid coolant channels, thereby dynamically responding to varying heat loads.

Edelstein, Fred (inventor); Brown, Richard F. (inventor)

1987-01-01

119

Modal structure of centrifugal pendulum vibration absorber systems with multiple cyclically symmetric groups of absorbers  

NASA Astrophysics Data System (ADS)

This work studies the symmetry breaking effects on the vibration mode structure of centrifugal pendulum vibration absorber (CPVA) systems when multiple groups of absorbers are used. An absorber group is a set of equally spaced, identical absorbers. Absorbers within a group are cyclically symmetric while the entire system is asymmetric because the groups have no pre-defined relative angular spacing. One rotational and two translational degrees of freedom for the rotor and a single arclength degree of freedom for each absorber are considered in the planar model. The well-defined structure of the vibration modes is obtained by analytical and numerical investigations of the associated eigenvalue problem. This vibration mode structure is similar to that for CPVA systems with equally spaced, identical absorbers. Thus, the disrupted symmetry from multiple absorber groups does not destroy the vibration mode structure resulting from the cyclic symmetry within each group. The critical speeds and flutter instability of the system are investigated.

Shi, Chengzhi; Parker, Robert G.

2013-09-01

120

Device for absorbing mechanical shock  

DOEpatents

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.

Newlon, Charles E. (Knoxville, TN)

1980-01-01

121

Torsional vibration reduction using passive nonlinear absorbers  

Microsoft Academic Search

This paper considers the dynamic performance of systems of centrifugal pendulum vibration absorbers that are used to attenuate torsional vibrations in rotating systems. These absorbers, which can be found in certain IC engines and helicopter rotors, consist of movable masses whose centers of mass are kinematically restricted to move along prescribed paths relative to the rotor of interest. The most

Steven W. Shaw; Abdallah Alsuwaiyan

2000-01-01

122

The design of broadband radar absorbing surfaces  

Microsoft Academic Search

There has been a growing and widespread interest in radar absorbing material technology. As the name implies, radar absorbing materials or RAM's are coatings whose electric and magnetic properties have been selected to allow the absorption of microwave energy at discrete or broadband frequencies. In military applications low radar cross section (RCS) of a vehicle may be required in order

Go H. Suk

1990-01-01

123

Application of magnetorheological elastomer to vibration absorber  

Microsoft Academic Search

Traditional dynamic vibration absorber (DVA) is widely used in industries as a vibration absorption equipment. However, it is only effective at narrow working frequency range. This shortcoming has limited its stability and application. This paper develops an adaptive tuned vibration absorber (ATVA) based on unique characteristics of magnetorheological elastomers (MREs), whose modulus can be controlled by an applied magnetic field.

Hua-Xia Deng; Xing-Long Gong

2008-01-01

124

Highly efficient special sound absorbing solutions  

NASA Technical Reports Server (NTRS)

Highly efficient special sound absorbing structures with the following criteria are considered: (1) A distribution surface of the sound absorbing material greater than that of the building element on which the structure is placed; (2) The highest possible absorption coefficient in the widest possible frequency band; and (3) adaptability to different construction and aesthetic conditions.

Ionescu, M.; Petre-Lazar, S.

1974-01-01

125

On-site wastewater treatment using unsaturated absorbent biofilters  

SciTech Connect

A new type of single-pass aerobic biofilter is being developed as an alternative to the conventional septic tile bed and for treatment of wastewater in general. The Waterloo Biofilter uses absorbent Inter media that combine long retention times, separate flowpaths for wastewater and air, and large surface areas, thereby enabling loading rates 10 times greater than that for solid particle filter media. Although absorbent sphagnum peat and coarse sand plug readily at loading rates of 50 to 80 cm d{sup -1}, absorbent plastic particles provide consistent treatment with no plugging problems. The latest field trial removes 97.8% BOD{sub 7}, 96.1% TSS, and 99.5% fecal conform bacteria with 12 to 16{degrees}C wastewater loaded at 49 cm d{sup -1}. Surge Bows up to 204 cm d{sup -1} over several days are handled with little effect on effluent quality. In laboratory column experiments, removal of fecal coliforms averages >99.99% at 80 cm d{sup -1} loading, and >99.999% at 10 cm d{sup -1} after a 10- to 14-d acclimatization period. Ammonium is thoroughly oxidized to NO{sub 3}{sup -} with typically <2.5 mg L{sup - 1} NH{sub 4}{sup +}-N in the effluent. Overall treatment improves with forced air flow compared with natural convection. Cold influent and plugging by freezing are the main causes of poor treatment. This biofilter could find general application in renovating polluted water, including water for domestic consumption in developing regions of the world. 29 refs., 7 figs., 6 tabs.

Jowett, E.C.; McMaster, M.L. [Univ. of Waterloo, Waterloo, Ontario (Canada)

1995-01-01

126

5 Ultra Cold Neutrons  

Microsoft Academic Search

At the Paul Scherrer Institut (PSI) a new source of ultra cold neutrons (UCN) will be con- structed with the goal to improve the sensitivity to the neutron electric dipole moment (nEDM), which is sensitive to possible contributions from new physics. In addition the neu- tron decay parameters such as its life time may be studied more accurately. Presently, we

P. Fierlinger; S. Heule; U. Straumann

127

Cold Facts about Viruses.  

ERIC Educational Resources Information Center

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…

Pea, Celeste; Sterling, Donna R.

2002-01-01

128

Teaching "In Cold Blood."  

ERIC Educational Resources Information Center

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 man for another, and the place…

Berbrich, Joan D.

1967-01-01

129

Galactic Cold Cores  

NASA Astrophysics Data System (ADS)

The aims of the project "Cold Cores" include the compilation of an extensive catalog of dense and cold interstellar dust clouds and the characterization of this source population at large scale in the Galaxy. The sources, which range from pre-stellar cores to already star-forming clouds, are being identified from the Planck satellite all-sky survey. With good coverage of sub-millimeter wavelengths, high sensitivity, and a spatial resolution comparable to that of IRAS satellite, Planck is ideal for this search. Herschel will be used for a more detailed study of some 150 Planck-detected target fields. The Herschel data, combined with ground based follow-up observations, are used to determine the evolutionary stages of the detected sources and to study their physical characteristics and dust properties. The Herschel results help us to better understand the initial phases of star formation and give a key to the statistical interpretation of the much larger sample of sources included in the Planck catalog. We describe the scientific goals of the project and show first results from Herschel Science Demonstration Phase observations. In the fields studied so far, observations have revealed isolated starless cores, cores with embedded sources, and cold dust clumps within regions of active star formation. Thus, the results already demonstrate the large variety of Galactic sources harboring cold dust.

Juvela, Mika; Ristorcelli, Isabelle

130

Expert Cold Structure Development  

NASA Astrophysics Data System (ADS)

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.

Atkins, T.; Demuysère, P.

2011-08-01

131

COLD NEUTRON SOURCES  

Microsoft Academic Search

Experimental work on cold neutron source development is reviewed along ; with the theoretical explanations devised for the results obtained. Factors ; governing source design, the associated cryogenic and safety problems, large ; source design, and experiments by which source efficiency might be increased are ; also discussed. (D.C.W.);

F WEBB

1963-01-01

132

Titanium Cold Spray Coatings  

NASA Astrophysics Data System (ADS)

Titanium Cold Spray Coatings Cold Spray is an emerging technology used for the deposition of coatings for many industries including aerospace. This technique allows the deposition of metallic materials at low temper-atures below their melting point. The aim of this research was to develop a test technique that can measure the degree to which a cold spray coating achieves mechanical properties similar to a traditional bulk material. Vickers hardness testing and nanoindentation were used as micro-and nano-scale measurement techniques to characterize the mechanical properties of titanium coatings, deposited at different deposition conditions, and bulk Ti. The mechanical properties of bulk titanium and titanium coatings were measured over a range of length scales, with the indentation size effect examined with Meyer's law. Hardness measurements are shown to be affected by material porosity, microstructure and coating particle bonding mechanism. Hard-ness measurements showed that Ti coatings deposited at higher gas pressures and temperatures demonstrate an indentation load response similar to bulk Ti. Key words: titanium, cold spray, Vickers hardness, nanoindentation, indentation size effect, microstructure, mechanical properties

Ajaja, Jihane; Goldbaum, Dina; Chromik, Richard; Yue, Stephen; Rezaeian, Ahmad; Wong, Wilson; Irissou, Eric; Legoux, Jean-Gabriel

133

Solar sustained plasma/absorber conceptual design  

NASA Technical Reports Server (NTRS)

A space power system concept was evaluated which uses concentrated solar energy to heat a working fluid to temperatures as high as 4000 K. The high temperature working fluid could be used for efficient electric power production in advanced thermal or magnetohydrodynamic conversion cycles. Energy absorber configurations utilizing particles or cesium vapor absorber material were investigaed. Results of detailed radiant heat transfer calculations indicated approximately 86 percent of the incident solar energy could be absorbed within a 12-cm-dia flowing stream of gas borne carbon particles. Calculated total energy absorption in the cesium vapor seeded absorber configuration ranged from 34 percent to 64 percent of the incident solar energy. Solar flux concentration ratios of between approximately 3000 and 10,000 will be required to sustain absorber temperatures in the range from 3000 K to 4000 K.

Rodgers, R. J.; Krascella, N. L.; Kendall, J. S.

1979-01-01

134

Thermoregulatory modeling for cold stress.  

PubMed

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. PMID:24944030

Xu, Xiaojiang; Tikuisis, Peter

2014-07-01

135

RADIATIVE TRANSFER IN A CLUMPY UNIVERSE. IV. NEW SYNTHESIS MODELS OF THE COSMIC UV/X-RAY BACKGROUND  

SciTech Connect

We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative transfer code CUBA: (1) the sawtooth modulation of the background intensity from resonant line absorption in the Lyman series of cosmic hydrogen and helium; (2) the X-ray emission from the obscured and unobscured quasars that gives origin to the X-ray background; (3) a piecewise parameterization of the distribution in redshift and column density of intergalactic absorbers that fits recent measurements of the mean free path of 1 ryd photons; (4) an accurate treatment of the photoionization structure of absorbers, which enters in the calculation of the helium continuum opacity and recombination emissivity; and (5) the UV emission from star-forming galaxies at all redshifts. We provide tables of the predicted H I and He II photoionization and photoheating rates for use, e.g., in cosmological hydrodynamics simulations of the Ly{alpha} forest and a new metallicity-dependent calibration to the UV luminosity density-star formation rate density relation. A 'minimal cosmic reionization model' is also presented in which the galaxy UV emissivity traces recent determinations of the cosmic history of star formation, the luminosity-weighted escape fraction of hydrogen-ionizing radiation increases rapidly with look-back time, the clumping factor of the high-redshift intergalactic medium evolves following the results of hydrodynamic simulations, and Population III stars and miniquasars make a negligible contribution to the metagalactic flux. The model provides a good fit to the hydrogen-ionization rates inferred from flux decrement and proximity effect measurements, predicts that cosmological H II (He III) regions overlap at redshift 6.7 (2.8), and yields an optical depth to Thomson scattering, {tau}{sub es} = 0.084 that is in agreement with Wilkinson Microwave Anisotropy Probe results. Our new background intensities and spectra are sensitive to a number of poorly determined input parameters and suffer from various degeneracies. Their predictive power should be constantly tested against new observations. We are therefore making our redshift-dependent UV/X emissivities and CUBA outputs freely available for public use at http://www.ucolick.org/{approx}pmadau/CUBA.

Haardt, Francesco [Dipartimento di Scienza e alta Tecnologia, Universita dell'Insubria, via Valleggio 11, 22100 Como (Italy); Madau, Piero, E-mail: haardt@uninsubria.it, E-mail: pmadau@ucolick.org [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

2012-02-20

136

Radiative Transfer in a Clumpy Universe. IV. New Synthesis Models of the Cosmic UV/X-Ray Background  

NASA Astrophysics Data System (ADS)

We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative transfer code CUBA: (1) the sawtooth modulation of the background intensity from resonant line absorption in the Lyman series of cosmic hydrogen and helium; (2) the X-ray emission from the obscured and unobscured quasars that gives origin to the X-ray background; (3) a piecewise parameterization of the distribution in redshift and column density of intergalactic absorbers that fits recent measurements of the mean free path of 1 ryd photons; (4) an accurate treatment of the photoionization structure of absorbers, which enters in the calculation of the helium continuum opacity and recombination emissivity; and (5) the UV emission from star-forming galaxies at all redshifts. We provide tables of the predicted H I and He II photoionization and photoheating rates for use, e.g., in cosmological hydrodynamics simulations of the Ly? forest and a new metallicity-dependent calibration to the UV luminosity density-star formation rate density relation. A "minimal cosmic reionization model" is also presented in which the galaxy UV emissivity traces recent determinations of the cosmic history of star formation, the luminosity-weighted escape fraction of hydrogen-ionizing radiation increases rapidly with look-back time, the clumping factor of the high-redshift intergalactic medium evolves following the results of hydrodynamic simulations, and Population III stars and miniquasars make a negligible contribution to the metagalactic flux. The model provides a good fit to the hydrogen-ionization rates inferred from flux decrement and proximity effect measurements, predicts that cosmological H II (He III) regions overlap at redshift 6.7 (2.8), and yields an optical depth to Thomson scattering, ?es = 0.084 that is in agreement with Wilkinson Microwave Anisotropy Probe results. Our new background intensities and spectra are sensitive to a number of poorly determined input parameters and suffer from various degeneracies. Their predictive power should be constantly tested against new observations. We are therefore making our redshift-dependent UV/X emissivities and CUBA outputs freely available for public use at http://www.ucolick.org/~pmadau/CUBA.

Haardt, Francesco; Madau, Piero

2012-02-01

137

Small Cold Temperature Instrument Packages  

Microsoft Academic Search

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

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

2011-01-01

138

COLD STORAGE DESIGN REFRIGERATION EQUIPMENT  

E-print Network

COLD STORAGE DESIGN AND REFRIGERATION EQUIPMENT REFRIGERATION OF FISH - PART 1 \\ "..\\- ,,, T I Fishery Leaflet 427 Washington 25, D. C. June 1956 REFRIGERATION OF FISH - PART em; COlD STORAGE DESIGN (Section 1), and F. Bruce Sanford (Section 1) Table of Contents Pages Section 1 - Cold Storage Design

139

Torsional vibration reduction using passive nonlinear absorbers  

NASA Astrophysics Data System (ADS)

This paper considers the dynamic performance of systems of centrifugal pendulum vibration absorbers that are used to attenuate torsional vibrations in rotating systems. These absorbers, which can be found in certain IC engines and helicopter rotors, consist of movable masses whose centers of mass are kinematically restricted to move along prescribed paths relative to the rotor of interest. The most common choice for absorber paths are simple circles that are slightly mistuned from the desired order, so that undesirable nonlinear behaviors are avoided when the absorbers undergo large amplitude motions. In this work we consider a range of different path types and tunings, with the goal of optimizing performance over a wide operating range. This analytical study relies on a mathematical model of a rotor fitted with N identical, general-path absorbers, and utilizes perturbation techniques to obtain analytical estimates for the response of the rotor and the absorbers. The results are used to select path parameters based on selected performance measures, and the results are verified via simulation studies. It is shown that slightly overtuned cycloidal paths provide excellent vibration reduction characteristics and prevent the occurrence of nonlinear instabilities and vibration localization in the response of the absorbers.

Shaw, Steven W.; Alsuwaiyan, Abdallah

2000-04-01

140

A thermally tunable terahertz metamaterial absorber  

NASA Astrophysics Data System (ADS)

A thermally tunable terahertz metamaterial absorber (MA) with InSb embedded in a metal-dielectric-metal structure is proposed. The transmission and tuning properties of the proposed metamaterial absorber are analyzed for the temperature ranging from 160 K to 350 K. The simulated results show that the maximum absorption of the absorber is nearly 99.8% at a full-width at half-maximum (FWHM) of 38 GHz, and the absorption frequency can be dynamically tuned from 0.82 THz to 1.02 THz.

Zheng, Wei; Li, Wei; Chang, Sheng-jiang

2015-01-01

141

Cold heteromolecular dipolar collisions.  

PubMed

Cold molecules promise to reveal a rich set of novel collision dynamics in the low-energy regime. By combining for the first time the techniques of Stark deceleration, magnetic trapping, and cryogenic buffer gas cooling, we present the first experimental observation of cold collisions between two different species of state-selected neutral polar molecules. This has enabled an absolute measurement of the total trap loss cross sections between OH and ND(3) at a mean collision energy of 3.6 cm(-1) (5 K). Due to the dipolar interaction, the total cross section increases upon application of an external polarizing electric field. Cross sections computed from ab initio potential energy surfaces are in agreement with the measured value at zero external electric field. The theory presented here represents the first such analysis of collisions between a (2)? radical and a closed-shell polyatomic molecule. PMID:21881670

Sawyer, Brian C; Stuhl, Benjamin K; Yeo, Mark; Tscherbul, Timur V; Hummon, Matthew T; Xia, Yong; K?os, Jacek; Patterson, David; Doyle, John M; Ye, Jun

2011-11-14

142

WISPy cold dark matter  

SciTech Connect

Very weakly interacting slim particles (WISPs), such as axion-like particles (ALPs) or hidden photons (HPs), may be non-thermally produced via the misalignment mechanism in the early universe and survive as a cold dark matter population until today. We find that, both for ALPs and HPs whose dominant interactions with the standard model arise from couplings to photons, a huge region in the parameter spaces spanned by photon coupling and ALP or HP mass can give rise to the observed cold dark matter. Remarkably, a large region of this parameter space coincides with that predicted in well motivated models of fundamental physics. A wide range of experimental searches — exploiting haloscopes (direct dark matter searches exploiting microwave cavities), helioscopes (searches for solar ALPs or HPs), or light-shining-through-a-wall techniques — can probe large parts of this parameter space in the foreseeable future.

Arias, Paola; Goodsell, Mark; Ringwald, Andreas [Deutsches Elektronen-Synchrotron, Notkestraße 85, D-22607 Hamburg (Germany); Cadamuro, Davide; Redondo, Javier [Max-Planck-Institut für Physik, Föhringer Ring 6, D-80805 München (Germany); Jaeckel, Joerg, E-mail: paola.arias@desy.de, E-mail: cadamuro@mppmu.mpg.de, E-mail: mark.goodsell@cern.ch, E-mail: joerg.jaeckel@durham.ac.uk, E-mail: redondo@mppmu.mpg.de, E-mail: andreas.ringwald@desy.de [Institute for Particle Physics Phenomenology, Durham University, Durham DH1 3LE (United Kingdom)

2012-06-01

143

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

NASA Astrophysics Data System (ADS)

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 log? 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.

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

2014-07-01

144

Cold denaturation of encapsulated ubiquitin.  

PubMed

Theoretical considerations suggest that protein cold denaturation can potentially provide a means to explore the cooperative substructure of proteins. Protein cold denaturation is generally predicted to occur well below the freezing point of water. Here NMR spectroscopy of ubiquitin encapsulated in reverse micelles dissolved in low viscosity alkanes is used to follow cold-induced unfolding to temperatures below -25 degrees C. Comparison of cold-induced structural transitions in a variety of reverse micelle-buffer systems indicate that protein-surfactant interactions are negligible and allow the direct observation of the multistate cold-induced unfolding of the protein. PMID:16910639

Pometun, Maxim S; Peterson, Ronald W; Babu, Charles R; Wand, A Joshua

2006-08-23

145

Teachers Debate Cold Fusion  

NASA Astrophysics Data System (ADS)

What follows is a collection of messages about cold fusion from teachers. The messages were posted on the internet discussion list, Phys-L, or were sent to me in private. They illustrate a wide range of opinion. Phys-L is a list dedicated to learning and teaching physics with 700 subscribers from over 35 countries, the majority of whom are physics educators. <>.

Kowalski, Ludwik

2005-12-01

146

Crazy Cold Air  

NSDL National Science Digital Library

In this classroom activity, students record the temperatures in and around a walk-in refrigerator or freezer to see how cold air behaves when it meets warmer air. The printable five-page handout includes a series of inquiry-based questions to get students thinking about how the temperature of air changes its density, detailed experiment directions and a worksheet that helps students use the experiment results to obtain insight into the wind patterns of Antarctica.

147

Familial Cold Autoinflammatory Syndrome  

PubMed Central

Familial cold autoinflammatory syndrome is an autosomal dominant inherited inflammatory disease characterized by episodes of rash, fever, and joint pain following generalized exposure to cold. Attacks usually occur 1–2 hours after exposure and last less than 24 hours. It has been reported primarily in families from North America and Europe, but sporadic cases have also been reported. The diagnosis is based on clinical presentation and can be confirmed by the identification of a NALP3 mutation. No clinical trials have been performed with FCAS patients, but anakinra, an IL-1 receptor antagonist, has been effective at preventing symptoms prior to a cold challenge and as a maintenance medication in several patients. The NALP3 gene, also known as CIAS1, is expressed in peripheral blood leukocytes and chondrocytes and codes a protein also known as Cryopyrin. NALP3 mutations have also been identified in Muckle Wells syndrome and Chronic infantile neurologic cutanaeous articular syndrome. There are several laboratories in Europe and North America where sequencing of NALP3 is performed. PMID:11590390

Hoffman, Doctor Hal M

2015-01-01

148

Cold Stowage Flight Systems  

NASA Technical Reports Server (NTRS)

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.

Campana, Sharon E.; Melendez, David T.

2011-01-01

149

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

NASA Astrophysics Data System (ADS)

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]?157 ?m, [O I] ?63 ?m and [O Ib] ?145 ?m. Additionally, we present H?+[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 H? 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 H?+[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 these systems may result in variable power output of the AGN jets, potentially triggering sporadic, larger outbursts. In the two cold-gas-poor, X-ray morphologically relaxed galaxies of our sample, NGC 1399 and NGC 4472, powerful AGN outbursts may have destroyed or removed most of the cold gas from the cores, allowing the jets to propagate and deposit most of their energy further out, increasing the entropy of the hot galactic atmospheres and leaving their cores relatively undisturbed.

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

150

Terahertz backscattering behavior of various absorbing materials  

NASA Astrophysics Data System (ADS)

The Submillimeter-Wave Technology Laboratory (STL) at the University of Massachusetts Lowell has investigated the electromagnetic scattering behavior of various broadband absorbers. Several absorbing materials were tested in a compact radar range operating at a center frequency of 160 GHz. The polarimetric radar cross section was measured at elevation angles from 15° to 75°. In addition to the backscattering behavior, the normal incidence transmittance of the materials was evaluated.

Wu, C.; Gatesman, A. J.; DeRoeck, L.; Horgan, T.; Giles, R. H.; Nixon, W. E.

2009-05-01

151

Perfect terahertz absorber using fishnet based metafilm  

SciTech Connect

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.

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

2009-01-01

152

21 CFR 878.4755 - Absorbable lung biopsy plug.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Absorbable lung biopsy plug. 878.4755 Section 878...Surgical Devices § 878.4755 Absorbable lung biopsy plug. (a) Identification. A preformed (polymerized) absorbable lung biopsy plug is intended to...

2014-04-01

153

Modal properties and stability of centrifugal pendulum vibration absorber systems with equally spaced, identical absorbers  

NASA Astrophysics Data System (ADS)

This work develops an analytical model of centrifugal pendulum vibration absorber systems with equally spaced, identical absorbers and uses it to investigate the structure of the modal vibration properties. The planar model admits two translational and one rotational degrees-of-freedom for the rotor and a single arclength degree-of-freedom for each absorber. The gyroscopic effects from rotor rotation are taken into account. Examination of the associated eigenvalue problem reveals well-defined structure of the vibration modes resulting from the cyclic symmetry of the absorbers. The vibration modes are classified into rotational, translational, and absorber modes. Characteristics of each mode type are analytically proved. The effects of the absorber tuning order on the modes are derived. The critical speeds and flutter instability of the system are studied numerically and analytically.

Shi, Chengzhi; Parker, Robert G.

2012-10-01

154

The Isis cold moderators  

SciTech Connect

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.

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

155

On the definition of absorbed dose  

NASA Astrophysics Data System (ADS)

Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before.

Grusell, Erik

2015-02-01

156

Is It A Cold Or The Flu? Symptoms Cold Flu  

E-print Network

Is It A Cold Or The Flu? Symptoms Cold Flu Fever Rare Usual, high (100-102°) Headache be severe 5 STEPS TO TAKE IF YOU GET THE FLU: 1. Stay at home and rest. CDC recommends that you stay home a medical condition that puts you at higher risk of flu complications (like asthma...), call your doctor

O'Toole, Alice J.

157

Is it a Cold or the Flu? Symptoms Cold Flu  

E-print Network

Is it a Cold or the Flu? Symptoms Cold Flu Fever Rare Usual; high (100°F to 102°F, occasionally higher, especially in young children); lasts 3 to 4 days Headache Rare Common General Aches, Pains Slight Usual; at the beginning of the illness Stuffy Nose Common Sometimes Sneezing Usual Sometimes Sore Throat

Weston, Ken

158

Is It a Cold or the Flu? Symptoms Cold Flu  

E-print Network

Is It a Cold or the Flu? Symptoms Cold Flu Fever Rare Usual; high (100°F to 102°F, occasionally higher, especially in young children); lasts 3 to 4 days Headache Rare Common General Aches, Pains Slight Usual; at the beginning of the illness Stuffy Nose Common Sometimes Sneezing Usual Sometimes Sore Throat

Bandettini, Peter A.

159

Ferrite HOM Absorber for the RHIC ERL  

SciTech Connect

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.

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

2008-10-01

160

Absorber Materials at Room and Cryogenic Temperatures  

SciTech Connect

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.

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

2011-09-01

161

Notes 10. The dynamic vibration absorber  

E-print Network

] Luis San Andres (c) 2008 MEEN 363 - 617 THE VIBRATION ABSORBER Preamble - A NEED arises: Consider the periodic forced response of a primary system (Kp-Mp) defined by X p (t) K p F(t) M P M p 10 3 lb?:= K p 110 5 ? lbf in ?:= Its natural frequency is... then determines that the stiffness and mass of the secondary system should be such that: TUNED ABSORBER ? X ? np = also known as a For example, if zero amplitude vibration is desired for excitations at the natural frequency of the original system, the designer...

San Andres, Luis

2008-01-01

162

Durability of Polymeric Glazing and Absorber Materials  

SciTech Connect

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.

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

2005-11-01

163

Coherent perfect absorber based on metamaterials  

NASA Astrophysics Data System (ADS)

We demonstrate selective coherent perfect absorption based on interaction between bilayered asymmetrically split rings (ASRs) metamaterials and a standing wave formed by two coherent counter propagating beams. The selective coherent perfect absorbers with high absorption have been achieved depending on the phase difference between two coherent beams. The selective coherent control absorbers can be well designed by changing the thickness of the dielectric layer and the asymmetry of the ASRs. The coherently controlled metamaterials provide an opportunity to realize selective multiband absorption and ultrafast information processing.

Nie, Guangyu; Shi, Quanchao; Zhu, Zheng; Shi, Jinhui

2014-11-01

164

Effect on source signal condition for pyramidal microwave absorber performance  

Microsoft Academic Search

In designing a microwave absorber for anechoic chamber, there are many condition can affect the performance of microwave absorber. In this work, four conditions are discussed to compare the reflectivity or S11 of the pyramidal microwave absorber. The conditions are different signal source position, areas, angle, and lastly the distance between signal source and pyramidal microwave absorber. These pyramidal microwave

H. Nornikman; F. Malek; P. J. Soh; A. A. H. Azremi

2010-01-01

165

The physics inside the scaling relations for X-ray galaxy clusters: gas clumpiness, gas mass fraction and slope of the pressure profile  

NASA Astrophysics Data System (ADS)

In galaxy clusters, the relations between observables in X-ray and millimetre wave bands and the total mass have normalizations, slopes and redshift evolutions that are simple to estimate in a self-similar scenario. We study these scaling relations and show that they can be efficiently expressed, in a more coherent picture, by fixing the normalizations and slopes to the self-similar predictions, and advocating, as responsible of the observed deviations, only three physical mass-dependent quantities: the gas clumpiness C, the gas mass fraction fg and the logarithmic slope of the thermal pressure profile ?P. We use samples of the observed gas masses, temperature, luminosities and Compton parameters in local clusters to constrain normalization and mass dependence of these three physical quantities, and measure C0.5fg = 0.110( ± 0.002 ± 0.002)(EzM/5 × 1014 M?)0.198( ± 0.025 ± 0.04) and ?P = -dln P/dln r = 3.14( ± 0.04 ± 0.02)(EzM/5 × 1014 M?)0.071( ± 0.012 ± 0.004), where both a statistical and systematic error (the latter mainly due to the cross-calibration uncertainties affecting the Chandra and XMM-Newton results used in the present analysis) are quoted. The degeneracy between C and fg is broken by using the estimates of the Compton parameters. Together with the self-similar predictions, these estimates on C, fg and ?P define an intercorrelated internally consistent set of scaling relations that reproduces the mass estimates with the lowest residuals.

Ettori, S.

2015-01-01

166

Cold Dark Matter Resuscitated?  

E-print Network

The Cold Dark Matter (CDM) model has an elegant simplicitly which makes it very predictive, but when its parameters are fixed at their `canonical' values its predictions are in conflict with observational data. There is, however, much leeway in the initial conditions within the CDM framework. We advocate a re-examination of the CDM model, taking into account modest variation of parameters from their canonical values. We find that CDM models with $n=0.8$--0.9 and $h=0.45$--0.50 can fit the available data. Our ``best fit'' CDM model has $n=0.9$, $h=0.45$ and $C_2^{T}/C_2^{S}=0.7$. We discuss the current state of observations which could definitely rule out this model.

Martin White; Douglas Scott; Joe Silk; Marc Davis

1995-08-02

167

Cold isopressing method  

DOEpatents

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.

Chen, Jack C. (Getzville, NY); Stawisuck, Valerie M. (North Tonawanda, NY); Prasad, Ravi (East Amherst, NY)

2003-01-01

168

The status of cold fusion  

NASA Astrophysics Data System (ADS)

This report attempts to update the status of the phenomenon of cold fusion. The new field is continuing to grow as a variety of nuclear reactions are discovered to occur in a variety of chemical environments at modest temperatures. However, it must be cautioned that most scientists consider cold fusion as something akin to UFO's, ESP, and numerology.

Storms, E.

169

Influence of Absorbers on the Electromagnetic Radiation  

E-print Network

The phenomenon of the electromagnetic absorption by arbitrarily distributed discrete absorbers is analyzed from the photon point of view. It is shown that apart from the decrease in the intensity of the signal the net effect of absorption includes a relative increase in the photon bunching.

Neil V. Budko

2007-12-05

170

Uncovering the Weakest Absorbers in AGN Spectra  

NASA Astrophysics Data System (ADS)

The exquisite far-UV sensitivity of the Cosmic Origins Spectrograph has yielded moderate-resolution AGN spectra of unprecedented quality with signal to noise ratios (S/N) of 50 per resolution element in some cases. This high data quality allows us to detect some of the weakest (W 10 mÅ) absorption features ever found in far-UV spectra including weak photoionized Ly? forest absorbers at column densities N > 1012 cm-2 that may trace significant numbers of baryons in the form of ionized hydrogen, weak broad HI absorbers with b > 40 km/s that potentially trace warm collisionally ionized gas, and weak metal-line counterparts to Ly? absorbers in the intergalactic medium. However, accurately identifying and measuring weak astrophysical absorbers requires detailed knowledge of the spectrograph detectors and the latest in flat-fielding techniques. We present the results of both interactive and automated line searches in several of the highest-quality (S/N=30-50) extragalactic COS datasets taken to date. We catalog weak narrow lines, broad absorption features, and comment on the applicability of these techniques to the larger catalog of COS observations with more modest S/N.

Danforth, Charles; Stocke, J. T.; Shull, J. M.; Pieri, M.; Savage, B.; France, K.; Penton, S.; Keeney, B.

2011-01-01

171

Aldehyde-containing urea-absorbing polysaccharides  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

172

Tuned mass absorber on a flexible structure  

NASA Astrophysics Data System (ADS)

The classic design of a tuned mass absorber is based on a simple two-mass analogy in which the tuned mass is connected to the structural mass with a spring and a viscous damper. In a flexible multi-degree-of-freedom structure the tuned mass absorber is typically introduced to provide damping of a specific mode. The motion of the point of attachment of the tuned mass absorber to the structure has not only a contribution from the targeted mode, but also a background contribution from other non-resonant modes. Similarly, the force provided by the tuned mass absorber is distributed between the targeted mode and the background modes. It is demonstrated how this effect can be included via a non-dimensional dynamic background flexibility coefficient, extracted from a classic modal analysis for the particular frequency of the selected mode. An explicit calibration procedure is developed starting with the desired maximum amplification, from which the device damper, mass and stiffness are determined, accounting for the background flexibility. Examples demonstrate the influence of the flexibility effect and the efficiency of the proposed procedure.

Krenk, Steen; Høgsberg, Jan

2014-03-01

173

Do Different Colors Absorb Heat Better?  

NSDL National Science Digital Library

Students test whether the color of a material affects how much heat it absorbs. They leave ice cubes placed in boxes made of colored paper (one box per color; white, yellow, red and black) in the sun, and predict in which colored box ice cubes melt first. They record the order and time required for the ice cubes to melt.

2014-09-18

174

Composition for absorbing hydrogen from gas mixtures  

DOEpatents

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.

Heung, Leung K. (Aiken, SC); Wicks, George G. (Aiken, SC); Lee, Myung W. (Aiken, SC)

1999-01-01

175

Development of a crash energy absorber  

E-print Network

A new energy absorbing cartridge, named the "Z-tube" was developed for use in a new conceptualized highway safety appurtenance. The Z-tube was developed to provide a low cost method of dissipating the kinetic energy of errant motor vehicles. The Z...

Bullard, Delbert Lance

1995-01-01

176

Observational Tests for Warm Absorber Hydro Models  

Microsoft Academic Search

Warm absorber spectra are characterized by the many lines from partially ionized intermediate-Z elements, and iron, detected with the grating instruments on Chandra and XMM-Newton. If these ions are formed in a gas which is in photoionization equilibrium, they correspond to a broad range of ionization parameters, although there is evidence for certain preferred values. A test for any dynamical

Timothy R. Kallman; A. Dorodnitsyn

2010-01-01

177

Shock absorber protects motive components against overloads  

NASA Technical Reports Server (NTRS)

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.

1965-01-01

178

75 FR 52213 - Cold Treatment Regulations  

Federal Register 2010, 2011, 2012, 2013, 2014

...305 [Docket No. APHIS-2006-0050] Cold Treatment Regulations AGENCY: Animal and...phytosanitary treatment regulations for cold treatment enclosures and procedures, including...document requires articles destined for cold treatment to be precooled at or below...

2010-08-25

179

Absorbed fractions for electrons in ellipsoidal volumes  

NASA Astrophysics Data System (ADS)

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.

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

2011-01-01

180

Imaging of Damped Ly-alpha Absorbers  

NASA Astrophysics Data System (ADS)

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.)

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

1998-05-01

181

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

DOEpatents

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.

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

2014-12-02

182

Cool Outflows and HI absorbers with SKA  

E-print Network

HI 21-cm absorption spectroscopy provides a unique probe of the cold neutral gas in normal and active galaxies from redshift z > 6 to the present day. We describe the status of HI absorption studies, the plans for pathfinders/precursors, the expected breakthroughs that will be possible with SKA1, and some limitations set by the current design.

Morganti, Raffaella; Curran, Stephen J; Members, the SKA HI SWG

2015-01-01

183

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

E-print Network

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 $10^{-17} \\div 10^{-18}\\,$W/sqrt(Hz). The Cold-Electron Bolometers (CEBs) technology is promising, having the required properties, 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.

Salatino, Maria; Mahashabde, Sumedh; Kuzmin, Leonid S; Masi, Silvia

2014-01-01

184

A new concept of RAM-Radiation Absorbent Material: Applying corrugated surfaces to improve reflectivity  

Microsoft Academic Search

Microwave absorbers or Radiation Absorbent Materials-RAM are normally made of blocks of wave-absorptive material to avoid the reflection of electromagnetic waves incidental on it. Mainly used in anechoic chambers, it comes in various designs such as pyramidal absorber, twisted pyramidal absorber, hollow pyramidal absorber, wedge absorber, multilayer dielectric absorber, and hybrid dielectric absorber, among others. This paper presents a new

M. W. B. Silva; L. C. Kretly

2011-01-01

185

Therapeutic opportunities for targeting cold pain pathways.  

PubMed

Cold pain is a frequent symptom in neuropathic pain. Compared to other pain modalities, such as heat pain, the mechanisms behind physiological and pathological cold pain remain elusive. Moreover, it is becoming increasingly evident that cold pain pharmacology differs between various neuropathic pain conditions, making mechanism-directed treatment based on an understanding of the underlying pathophysiological mechanisms imperative to achieving clinical success. Here we review the processes of physiological and abnormal cold sensing, the pharmacology of cold nociception, cold hyperalgesia and cold allodynia, and provide an overview of cold pain syndromes and their current and potential treatments. PMID:25316567

Yin, Kathleen; Zimmermann, Katharina; Vetter, Irina; Lewis, Richard J

2015-01-15

186

a Standing-Wave Sloshing Absorber to Control Transient Oscillations  

NASA Astrophysics Data System (ADS)

The primary purpose of this study is to introduce a sloshing absorber as a practical alternative to the damped tuned absorber. In addition, a numerical simulation procedure is introduced as a computer-aided design tool. The problem of interest is the control of excessive oscillations of a mechanical oscillator in response to an initial displacement. Tuned vibration absorbers are frequently used for this purpose, and if damping is included in the tuned absorber, control action is quite effective. The problem, however, is that inclusion of an energy dissipation element necessitates frequent maintenance in practice. The suggested control technique here is a sloshing absorber, in place of the damped tuned vibration absorber. In contrast to a tuned absorber, a sloshing absorber accomplishes energy dissipation through sloshing. Therefore, it may be virtually maintenance free. Also for practical applications, this type of absorber can be an advantage where existing water storage tanks can be modified to control vibrations of the supporting structure.

ANDERSON, J. G.; SEMERCIGIL, S. E.; TURAN, Ö. F.

2000-05-01

187

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

188

[The "cold" thyroid nodule].  

PubMed

The main problem posed by an (apparent) solitary thyroid nodule is cancer identification, present in about 10% of the nodules excised surgically. This percent might increase to 25-30% in the cold scintigraphic nodules. Therefore, a combination of all the methods for nodule assessment is necessary: anamnesis, physical examination, functional tests, therapeutic test with tyrosine and thyroid imaging, but mainly the intensive active exploration including puncture-biopsy with a fine needle and exeresis with extemporaneous and paraffin morphological checking. Starting from a two decades' experience of a group of endocrinologists, surgeons, anatomo-pathologists and specialists in nuclear medicine, in 2,289 thyropathies operated--of whom 1691 (poly)nodular goitres and 1,190 non-capturing nodules--the authors suggest an investigation algorithm for achieving a differentiated surgery in terms of the pre- and intraoperative morphological findings. This attitude permitted both the improvement of the surgeries of thyroid cancers and the exeresis of benign nodules under low-risk surgical conditions or avoidance of a "non-necessary" surgery. PMID:2149188

Diaconescu, M R; Strat, V; Chifan, M; Georgescu, S; Bordea, M; Zbranca, E; Mogo?, V; G?le?anu, C; Dobrescu, G; Baran, T

1990-01-01

189

Cold Spring Harbor Laboratory  

NSDL National Science Digital Library

Established in 1890, the Cold Spring Harbor Laboratory (CSHL) is one of the best-known and most respected private research institutions in the United States. Over the past century, the Laboratory has supported the careers of seven Nobel Prize recipients and it is particularly well-regarded for its work in the field of genetics research. Today, there are over 400 scientists who work at the facility in Long Island, and their work ranges across the areas of cancer, neuroscience, genomics, and bioinformatics. Their website is a cornucopia of information on their activities, and first-time visitors should start by reading over the "CSHL Headlines" scrolling updates on the homepage. After that, they can look at the "Research" section. Here they will find overviews of their primary research groups and links to some of their specialized facilities, like the Dolan DNA Learning Center. Most visitors will want to visit the "Library and Archives" section. Here they can learn about CSHL authors' publications and look through the digital collections. The digital collections include tributes to Barbara McClintock, who was awarded the Nobel Prize in 1983, and who worked at the Laboratory for four decades.

190

Friendly units for coldness  

E-print Network

Measures of temperature that center around human experience get lots of use. Of course thermal physics insights of the last century have shown that reciprocal temperature (1/kT) has applications that temperature addresses less well. In addition to taking on negative absolute values under population inversion (e.g. of magnetic spins), bits and bytes turn 1/kT into an informatic measure of the thermal ambient for developing correlations within any complex system. We show here that, in the human-friendly units of bytes and food Calories, water freezes when 1/kT ~200 ZB/Cal or kT ~5 Cal/YB. Casting familiar benchmarks into these terms shows that habitable human space requires coldness values (part of the time, at least) between 0 and 40 ZB/Cal with respect body temperature ~100 degrees F, a range in kT of ~1 Cal/YB. Insight into these physical quantities underlying thermal equilibration may prove useful for budding scientists, as well as the general public, in years ahead.

Fraundorf, P

2006-01-01

191

Microscopic mechanism for cold denaturation  

E-print Network

We elucidate the mechanism of cold denaturation through constant-pressure simulations for a model of hydrophobic molecules in an explicit solvent. We find that the temperature dependence of the hydrophobic effect is the driving force/induces/facilitates cold denaturation. The physical mechanism underlying this phenomenon is identified as the destabilization of hydrophobic contact in favor of solvent separated configurations, the same mechanism seen in pressure induced denaturation. A phenomenological explanation proposed for the mechanism is suggested as being responsible for cold denaturation in real proteins.

Cristiano L. Dias; Tapio Ala-Nissila; Mikko Karttunen; Ilpo Vattulainen; Martin Grant

2007-04-20

192

Plants in a cold climate.  

PubMed Central

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

Smallwood, Maggie; Bowles, Dianna J

2002-01-01

193

HDPE/MWCNT composite as microwave absorber  

NASA Astrophysics Data System (ADS)

A HDPE/CNT composite has been fabricated based on a commercial polyethylene loaded with a high concentration of CVD grown multiwalled carbon nanotubes with a high aspect ratio. Exploiting the resulting high conductivity of this composite material, we tested the possibility to use it as absorber of electromagnetic waves at microwave frequencies up to 25 GHz. For this purpose the device under test was placed as substrate of a microstrip transmission line. Measurements of the scattering parameters, done with a vectorial network analyzer, have been used in order to obtain the power absorption at different frequencies. Special attention was paid to the optimization of the microstrip geometry. A comparison of the microwave power absorption spectrum with those of commercial cavity absorbers showed encouraging results, regarding the microwave absorption capability of the HDPE/CNT composite material.

Di Giacomo, R.; Neitzert, H. C.

2014-05-01

194

Disposable Diaper Absorbency: Improvements via Advanced Designs.  

PubMed

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. PMID:24961785

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

2014-06-24

195

Investigations on Absorber Materials at Cryogenic Temperatures  

SciTech Connect

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.

Frank Marhauser, Thomas Elliott, Robert Rimmer

2009-05-01

196

Shock wave absorber having apertured plate  

DOEpatents

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.

Shin, Yong W. (Western Springs, IL); Wiedermann, Arne H. (Chicago Heights, IL); Ockert, Carl E. (Vienna, VA)

1985-01-01

197

Shock wave absorber having apertured plate  

DOEpatents

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.

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

1983-08-26

198

Impedance matched thin metamaterials make metals absorbing  

PubMed Central

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

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

2013-01-01

199

Impedance matched thin metamaterials make metals absorbing  

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

200

High-performance THz metamaterial absorber  

E-print Network

We demonstrated an ultra-broadband, polarization-insensitive and wide-angle metamaterial absorber for terahertz (THz) frequencies using arrays of truncated pyramid unit structure made of metal-dielectric multilayer composite. In our design each sub-layer behaving as an effective waveguide is gradually modified in their lateral width to realize a wideband response by effectively stitching together the resonance bands of different waveguide modes. Experimentally, our five layer sample with a total thickness 21um is capable of producing a large absorptivity above 80% from 0.7 to 2.3 THz up to the maximum measurement angle 40{\\deg}. The full absorption width at half maximum (FWHM) of our device is around 127%, greater than those previously reported for THz frequencies. Our absorber design has high practical feasibility and can be easily integrated with the semiconductor technology to make high efficient THz-oriented devices.

Zhu, Jianfei; Sun, Wujiong; Ding, Fei; He, Qiong; Zhou, Lei; Ma, Yungui

2014-01-01

201

Absorbing Software Testing into the Scrum Method  

NASA Astrophysics Data System (ADS)

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.

Tuomikoski, Janne; Tervonen, Ilkka

202

Ultra-broadband terahertz metamaterial absorber  

NASA Astrophysics Data System (ADS)

We demonstrated an ultra-broadband, polarization-insensitive, and wide-angle metamaterial absorber for terahertz (THz) frequencies using arrays of truncated pyramid unit structure made of metal-dielectric multilayer composite. In our design, each sub-layer behaving as an effective waveguide is gradually modified in their lateral width to realize a wideband response by effectively stitching together the resonance bands of different waveguide modes. Experimentally, our five layer sample with a total thickness 21 ?m is capable of producing a large absorptivity above 80% from 0.7 to 2.3 THz up to the maximum measurement angle 40°. The full absorption width at half maximum of our device is around 127%, greater than those previously reported for THz frequencies. Our absorber design has high practical feasibility and can be easily integrated with the semiconductor technology to make high efficient THz-oriented devices.

Zhu, Jianfei; Ma, Zhaofeng; Sun, Wujiong; Ding, Fei; He, Qiong; Zhou, Lei; Ma, Yungui

2014-07-01

203

Optical guiding of absorbing nanoclusters in air  

E-print Network

We introduce a novel approach for all-optical trapping and manipulation of absorbing aerosol particles based on a photophoretic force. We demonstrate experimentally, in open air, the robust three-dimensional guiding of agglomerates of carbon nanoparticles with the size spanned for two orders of magnitude, from 100 nanometers to 10 microns, over the distances of a few millimeters, as well as their acceleration up to velocities of 1 cm/s and simultaneous trapping of a large number of particles.

Shvedov, Vladlen G; Rode, Andrei V; Krolikowski, Wieslaw Z; Kivshar, Yuri S

2009-01-01

204

Dielectric studies of water absorbed in epoxies  

E-print Network

ent) Nay 1987 ABSTRACT Dielectric Studies of Mater Absorbed in Epoxies. (May 1987) Ha I)uoc Pham, B. S. , Tokyo University of Agriculture Chairman of Advisory Committee: C. A. J. Hoeve Epoxy resins are industrially important polymers... of speculation. Since water has a large dipole moment, its mobility and inter- action with polymers can be studied by dielectric spectroscopy as a function of temperature, frequency, and water content, in an alter- nating electric field. Hoeve and co...

Pham, Ha Quoc

2012-06-07

205

Design and Manufacture of Energy Absorbing Materials  

ScienceCinema

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.

Duoss, Eric

2014-05-30

206

Tech Transfer Webinar: Energy Absorbing Materials  

SciTech Connect

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.

Duoss, Eric

2014-06-17

207

Plasmonic absorbers for multispectral and broadband absorption  

NASA Astrophysics Data System (ADS)

We present polarization dependent multispectral and broadband plasmonic absorbers in the visible spectrum. The spectral characteristics of these structures are tunable over a broad spectrum. Experimental results are verified with the FDTD and RCWA analysis methods. These structures are used as surface enhanced raman spectroscopy(SERS) substrates. Designed structures have resonances that span the Raman Stokes and excitation wavelength. Such structures can be used for energy, LED and other spectroscopy applications.

Ayas, Sencer; Guner, Hasan; Turker, Burak; Ekiz, Oner; Dana, Aykutlu

2012-03-01

208

Design and Manufacture of Energy Absorbing Materials  

SciTech Connect

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.

Duoss, Eric

2014-05-28

209

BIOCHEMISTRY: An Absorbing Study of Cholesterol  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. We obtain sterols from the animal and plant food that we eat. How these plant and animal sterols are absorbed, transported around the body, and excreted has been the subject of much investigation. In a Perspective, Allayee and colleagues discuss a new study (Berge et al.) that implicates two new ABC transporter proteins in the efflux of plant and animal sterols from gut epithelial cells into the gut lumen.

Hooman Allayee (University of California, Los Angeles (UCLA) School of Medicine;Department of Medicine and the Department of Microbiology, Immunology and Molecular Genetics); Bryan A. Laffitte (University of California, Los Angeles (UCLA) School of Medicine;Howard Hughes Medical Institute); Aldons J. Lusis (University of California, Los Angeles (UCLA) School of Medicine;Department of Medicine and the Department of Microbiology, Immunology and Molecular Genetics)

2000-12-01

210

Dealing with Cold Weather Injuries  

MedlinePLUS

... this page, please enable JavaScript. Dealing With Cold Weather Injuries Safety precautions can prevent serious problems during ... clothing should be removed and replaced with warm, dry clothes or blankets. People with hypothermia should also ...

211

Shock wave absorber having a deformable liner  

DOEpatents

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.

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

1983-08-26

212

COSMIC DUST IN Mg II ABSORBERS  

SciTech Connect

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.

Menard, Brice [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Fukugita, Masataka [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8583 (Japan)

2012-08-01

213

Cold binary and ternary fission  

Microsoft Academic Search

Summary  Cold binary fission has been studied in the spontaneous decay of252Cf (sf). Cold fission for the mass split 132\\/120 is especially interesting because here it is the doubly magic132 Sn which is dominating the yield for a range of total excitation energies 0 ? TXE ?10MeV For the reaction242Am(n,f) induced by thermal neutrons the yields of the heaviest clusters being

F. Gönnenwein; A. Möller; M. Cröni; M. Hesse; M. Wöstheinrich; H. Faust; G. Fioni; S. Oberstedt

1997-01-01

214

Sinusitis in the common cold  

Microsoft Academic Search

Background: Acute community-acquired sinusitis is considered a bacterial complication of the common cold. Radiologic abnormalities in sinuses occur, however, in most patients with upper respiratory virus infections.Objective: Assessment of the occurrence, clinical profile, laboratory findings, and outcome of radiologically confirmed sinusitis was carried out as part of a common cold study in young adults.Methods: Clinical examinations and radiography of the

Tuomo Puhakka; Mika J. Mäkelä; Anu Alanen; Timo Kallio; Leo Korsoff; Pertti Arstila; Maija Leinonen; Markku Pulkkinen; Jouko Suonpää; Jussi Mertsola; Olli Ruuskanen

1998-01-01

215

Antibiotic use for common cold  

Microsoft Academic Search

Antibiotics do not help patients with an uncomplicated common cold. Antibiotics can have side effects for the individual taking\\u000a them that range from unpleasant to serious, even lethal. Antibiotic use also contributes to communal harm by encouraging antibiotic\\u000a resistance. If there can be no benefit, but there can be harm, why is the common cold the commonest reason for doctors

Timothy W. Kenealy; Bruce Arroll

216

Warm absorbers in X-rays (WAX), a comprehensive high-resolution grating spectral study of a sample of Seyfert galaxies - I. A global view and frequency of occurrence of warm absorbers.  

NASA Astrophysics Data System (ADS)

We present results from a homogeneous analysis of the broad-band 0.3-10 keV CCD resolution as well as of the soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. Our goal is to characterize warm absorbers (WAs) along the line of sight to the active nucleus. We significantly detect WAs in 65 per cent of the sample sources. Our results are consistent with WAs being present in at least half of the Seyfert galaxies in the nearby Universe, in agreement with previous estimates. We find a gap in the distribution of the ionization parameter in the range 0.5 < log ? < 1.5 which we interpret as a thermally unstable region for WA clouds. This may indicate that the WA flow is probably constituted by a clumpy distribution of discrete clouds rather than a continuous medium. The distribution of the WA column densities for the sources with broad Fe K? lines are similar to those sources which do not have broadened emission lines. Therefore, the detected broad Fe K? emission lines are bona fide and not artefacts of ionized absorption in the soft X-rays. The WA parameters show no correlation among themselves, with the exception of the ionization parameter versus column density. The shallow slope of the log ? versus log vout linear regression (0.12 ± 0.03) is inconsistent with the scaling laws predicted by radiation or magnetohydrodynamic-driven winds. Our results also suggest that WA and ultra fast outflows do not represent extreme manifestation of the same astrophysical system.

Laha, Sibasish; Guainazzi, Matteo; Dewangan, Gulab C.; Chakravorty, Susmita; Kembhavi, Ajit K.

2014-07-01

217

An H I Column Density Threshold for Cold Gas Formation in the Galaxy  

NASA Astrophysics Data System (ADS)

We report the discovery of a threshold in the H I column density of Galactic gas clouds below which the formation of the cold phase of H I is inhibited. This threshold is at N H I = 2 × 1020 cm-2 sight lines with lower H I column densities have high spin temperatures (median Ts ~ 1800 K), indicating low fractions of the cold neutral medium (CNM), while sight lines with N H I >= 2 × 1020 cm-2 have low spin temperatures (median Ts ~ 240 K), implying high CNM fractions. The threshold for CNM formation is likely to arise due to inefficient self-shielding against ultraviolet photons at lower H I column densities. The threshold is similar to the defining column density of a damped Ly? absorber; this indicates a physical difference between damped and sub-damped Ly? systems, with the latter class of absorbers containing predominantly warm gas.

Kanekar, N.; Braun, R.; Roy, N.

2011-08-01

218

Compressed absorbing boundary conditions for the Helmholtz equation  

E-print Network

Absorbing layers are sometimes required to be impractically thick in order to offer an accurate approximation of an absorbing boundary condition for the Helmholtz equation in a heterogeneous medium. It is always possible ...

Bélanger-Rioux, Rosalie

2014-01-01

219

Garlic for the common cold.  

PubMed

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 There is insufficient clinical trial evidence regarding the effects of garlic in preventing or treating the common cold. A single trial suggested that garlic may prevent occurrences of the common cold but more studies are needed to validate this finding. Claims of effectiveness appear to rely largely on poor-quality evidence. PMID:25386977

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

2014-01-01

220

Optical properties of absorbing and non-absorbing aerosols retrieved by cavity ring down (CRD) spectroscopy  

NASA Astrophysics Data System (ADS)

Application of cavity ring down (CRD) spectrometry for measuring the optical properties of pure and mixed laboratory-generated aerosols is presented. The extinction coefficient (?ext), extinction cross section (?ext) and extinction efficiency (Qext) were measured for polystyrene spheres (PSS), ammonium sulphate ((NH4)2(SO4), sodium chloride (NaCl), glutaric acid (GA), and Rhodamine-590 aerosols. The refractive indices of the different aerosols were retrieved by comparing the measured extinction efficiency of each aerosol type to the extinction predicted by Mie theory. Aerosols composed of sodium chloride and glutaric acid in different mixing ratios were used as model for mixed aerosols of two non-absorbing materials, and their extinction and complex refractive index were derived. Aerosols composed of Rhodamine-590 and ammonium sulphate in different mixing ratios were used as model for mixing of absorbing and non-absorbing species, and their optical properties were derived. The refractive indices of the mixed aerosols were also calculated by various optical mixing rules. We found that for non-absorbing mixtures, the linear rule, Maxwell-Garnett rule, and extended effective medium approximation (EEMA), give comparable results, with the linear mixing rule giving a slightly better fit than the others. Overall, calculations for the mixed aerosols are not as good as for single component aerosols. For absorbing mixtures, the differences between the refractive indices calculated using the mixing rules and those retrieved by CRD are generally higher.

Abo Riziq, A.; Erlick, C.; Dinar, E.; Rudich, Y.

2007-03-01

221

Optical properties of absorbing and non-absorbing aerosols retrieved by cavity ring down (CRD) spectroscopy  

NASA Astrophysics Data System (ADS)

Application of cavity ring down (CRD) spectrometry for measuring the optical properties of pure and mixed laboratory-generated aerosols is presented. The extinction coefficient (?ext), extinction cross section (?ext) and extinction efficiency (Qext) were measured for polystyrene spheres (PSS), ammonium sulphate ((NH4)2(SO4)), sodium chloride (NaCl), glutaric acid (GA), and Rhodamine-590 aerosols. The refractive indices of the different aerosols were retrieved by comparing the measured extinction efficiency of each aerosol type to the extinction predicted by Mie theory. Aerosols composed of sodium chloride and glutaric acid in different mixing ratios were used as model for mixed aerosols of two non-absorbing materials, and their extinction and complex refractive index were derived. Aerosols composed of Rhodamine-590 and ammonium sulphate in different mixing ratios were used as model for mixing of absorbing and non-absorbing species, and their optical properties were derived. The refractive indices of the mixed aerosols were also calculated by various optical mixing rules and a core plus shell Mie model. We found that for non-absorbing mixtures, the linear rule, Maxwell-Garnett rule, extended effective medium approximation (EEMA), and core plus shell model give comparable results, with the linear mixing rule giving a slightly better fit than the others. Overall, calculations for the mixed aerosols are not as good as for single component aerosols. For absorbing mixtures, the differences between the refractive indices calculated using the mixing rules and those retrieved by CRD are generally higher.

Riziq, A. A.; Erlick, C.; Dinar, E.; Rudich, Y.

2006-11-01

222

14 CFR 29.475 - Tires and shock absorbers.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Tires and shock absorbers. 29.475 Section 29.475... Ground Loads § 29.475 Tires and shock absorbers. Unless otherwise prescribed...assumed to be in their static position and the shock absorbers to be in their most critical...

2011-01-01

223

14 CFR 29.475 - Tires and shock absorbers.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Tires and shock absorbers. 29.475 Section 29.475... Ground Loads § 29.475 Tires and shock absorbers. Unless otherwise prescribed...assumed to be in their static position and the shock absorbers to be in their most critical...

2010-01-01

224

14 CFR 27.475 - Tires and shock absorbers.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Tires and shock absorbers. 27.475 Section 27.475... Ground Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed...assumed to be in their static position and the shock absorbers to be in their most critical...

2010-01-01

225

14 CFR 27.475 - Tires and shock absorbers.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Tires and shock absorbers. 27.475 Section 27.475... Ground Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed...assumed to be in their static position and the shock absorbers to be in their most critical...

2011-01-01

226

Electrical tree initiation in polyethylene absorbing Penning gas  

Microsoft Academic Search

AC tree initiation voltage was examined in untreated LDPE, vacuum degassed LDPE and LDPE absorbing He gas (He gas was absorbed after vacuum degassing). The authors have already reported that vacuum degassed LDPE shows much higher tree initiation voltage than untreated LDPE because of the absence of oxygen. Therefore they expected that LDPE absorbing He would show the same property

N. Shimizu; N. Tohyama; H. Sato

1996-01-01

227

Wet waste flue gas desulfurizing process using lime as absorbent  

Microsoft Academic Search

A wet waste flue gas desulfurizing process using lime as absorbent is disclosed wherein a sulfur oxide-containing waste flue gas is washed with a liquid absorbent containing calcium hydroxide or calcium carbonate for the purpose of removing the sulfur oxide from said waste flue gas, characterized in that an absorbing device is divided into two stages, i.e., a former stage

M. Atsukawa; K. Kamei; N. Shinoda; H. Ushio

1977-01-01

228

Investigation of oil palm ash microwave absorber for broadband application  

Microsoft Academic Search

The investigation of oil palm ash microwave absorbers involves the design, simulation and fabrication of an effective broadband frequency for anechoic chamber. The resistive and magnetic materials in the oil palm ash compose its potential to be used as microwave absorbing materials. These oil palm ash absorbers are simulated using CST Microwave Studio. The arch measurement is executed to investigate

Ida Rahayu Mohamed Noordin; Hasnain Abdullah Idris; Mohd Nasir Taib; Anis Diyana Rosli; Asmalia Zanal; Ahmad Takiyuddin Abdullah

2012-01-01

229

Quantitative Photo-Acoustic Imaging of Small Absorbers Habib Ammari  

E-print Network

Quantitative Photo-Acoustic Imaging of Small Absorbers Habib Ammari Emmanuel Bossy Vincent Jugnon Hyeonbae Kang§ December 1, 2009 Abstract In photo-acoustic imaging, energy absorption causes thermo absorber from the absorbed density. AMS subject classifications. 31B20, 35B37,35L05 Key words. photo

Kang, Hyeonbae

230

A resonant point absorber of ocean-wave power  

Microsoft Academic Search

A system for absorbing and utilizing the energy carried by ocean waves is discussed. The 'point absorber' considered is a system in which the horizontal extent is much smaller than one wavelength. The point absorber is optimized for efficient energy conversion. The resonant characteristic frequency of the system is at all times tuned to the characteristic frequency of the wave.

K. Budar; J. Falnes

1975-01-01

231

Optimization of the tubular absorber using a compound parabolic concentrator  

Microsoft Academic Search

The paper deals with the optimization of the tubular absorber of a compound parabolic concentrator (CPC) solar collector. In order to minimize the radiation thermal losses from the absorber, a modified absorber with multi-cavities is proposed. The cavities are introduced at the circumferential area with relatively high solar intensities. These areas were determined by the use of a ray-tracing technique.

H. E. I. Khonkar; A. A. M. Sayigh

1995-01-01

232

Collector with cusplike compound parabolic concentrator and selective absorber  

Microsoft Academic Search

A nonevacuated solar collector with a cusplike compound parabolic concentrator (CPC) and tubular absorber has been built. Since the reflector surrounds the absorber on all sides, little insulating material is needed. Furthermore, the quantity of absorber material relative to unit collector aperture is smaller than in any other collector of comparable acceptance angle. This feature optimizes both transient response and

A. Rabl

1976-01-01

233

Bellows joint absorbs torsional deflections in duct system  

NASA Technical Reports Server (NTRS)

Long, thin-walled bellows compressed into a short length absorbs the same amount of torsional deflection as the same tube in full length condition and saves in cost, complexity and space. This bellows has lower torsional spring rate to absorb the bulk of the duct assembly tortional deflections, leaving the other bellows free to absorb axial and angular deflections.

Daniels, C. M.

1966-01-01

234

40 CFR 65.150 - Absorbers used as control devices.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Absorbers used as control devices. 65.150 Section 65.150...FEDERAL AIR RULE Closed Vent Systems, Control Devices, and Routing to a Fuel Gas System...Process § 65.150 Absorbers used as control devices. (a) Absorber equipment...

2010-07-01

235

40 CFR 65.150 - Absorbers used as control devices.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Absorbers used as control devices. 65.150 Section 65.150...FEDERAL AIR RULE Closed Vent Systems, Control Devices, and Routing to a Fuel Gas System...Process § 65.150 Absorbers used as control devices. (a) Absorber equipment...

2011-07-01

236

Numerical Study of Cold Store in Cold Storage Supply Chain and Logistics  

Microsoft Academic Search

The management of cold storage chain is an important part of the management of supply chain and logistics. The development of Chinese cold storage chain logistics is relatively backward, which affects the food industry seriously. Cold store play an important role in cold storage chain logistics. The field flow is the key technological parameter in cold store. A three dimensional

Gong Jianying; Pu Liang; Zhang Huajun

2010-01-01

237

[Performance of desulfurizing absorbent of roasted navajoite].  

PubMed

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. PMID:20527168

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

2010-04-01

238

The control of transpiration by absorbed radiation  

NASA Astrophysics Data System (ADS)

Transpiration plays a key role in the hydrological cycle and models of transpiration have been used in many applications. However, our understanding of mechanisms which control the rate of transpiration is still limited being a domain of two different disciplines. Meteorologists apply the top-down approach driven by physical descriptions and water vapour transport, stomatal conductance is regarded as a boundary condition. Plant physiologists focus on the bottom-up approach and emphasize the physiological control of transpiration by stomatal conductance. It is generally accepted that transpiration is strongly influenced by the boundary layer outside the leaf and that feedback mechanisms within this layer decrease the sensitivity of transpiration to changes in stomatal conductance. This feedback mechanism is thought to increase with increasing scale from single stoma to canopy and ecosystem. In contrast, we propose a mechanism that would place much of the control inside the leaf. Most of the solar radiation reaching the leaf penetrates the epidermis with little interaction and the largest part of the energy is absorbed by chloroplasts in mesophyll cells. Thus, evaporation occurs into the intercellular air spaces of a leaf at cell walls adjacent to the chloroplasts of the leaf mesophyll and it is directly coupled to absorbed solar radiation. We present data showing that variation in the rate of transpiration and stomatal conductance at constant humidity and CO2 is closely proportional to changes in fluxes of energy (W m-2) absorbed by the leaf. Computer simulations of energy exchange between the leaf mesophyll and the atmosphere with different regimes of heat and water exchange operating on the inner and outer sides of the epidermis realistically simulate transpiration, stomatal response to a range of environmental conditions and provide a basis to calculate carbon fluxes. This approach has the potential for an up-scaling of water and carbon fluxes in canopies and ecosystems.

Pieruschka, Roland; Berry, Joseph A.

2010-05-01

239

Acoustical model of a Shoddy fibre absorber  

NASA Astrophysics Data System (ADS)

Shoddy fibres or "Shoddies" are a mixture of post-consumer and post-industrial fibres diverted from textile waste streams and recycled into their raw fibre form. They have found widespread use as a raw material for manufacturing sound absorbers that include, but are not limited to: automotive, architectural and home appliance applications. The purpose of this project is to develop a simple acoustic model to describe the acoustic behaviour of sound absorbers composed primarily of Shoddy fibres. The model requires knowledge of the material's bulk density only. To date, these materials have not been the focus of much published research and acoustical designers must rely on models that were developed for other materials or are overly complex. For modelling purposes, an equivalent fluid approach is chosen to balance complexity and accuracy. In deriving the proposed model, several popular equivalent fluid models are selected and the required input parameters for each model identified. The models are: the model of Delaney and Bazley, two models by Miki, the model of Johnson in conjunction with the model of Champoux and Allard and the model of Johnson in conjunction with the model of Lafarge. Characterization testing is carried out on sets of Shoddy absorbers produced using three different manufacturing methods. The measured properties are open porosity, tortuosity, airflow resistivity, the viscous and thermal characteristic lengths and the static thermal permeability. Empirical relationships between model parameters and bulk density are then derived and used to populate the selected models. This yields several 'simplified' models with bulk density as the only parameter. The most accurate model is then selected by comparing each model's prediction to the results of normal incidence sound absorption tests. The model of Johnson-Lafarge populated with the empirical relations is the most accurate model over the range of frequencies considered (approx. 300 Hz - 4000 Hz) Characterization testing yields specific values for intrinsic material parameters that allow for comparison to other porous materials. Individual parameter relations allow users to substitute measured or theoretical values as needed. A new empirical acoustical model is proposed to describe the behaviour of Shoddy-based fibre absorbers. The model requires knowledge of the bulk density only. This parameter is easily measured making application of the model elementary. Mots-clés : Shoddy, porous, fibre, recycled, absorption, model, acoustic.

Manning, John Peter

240

Absorbing photonic crystals for thin film photovoltaics  

E-print Network

The absorption of thin hydrogenated amorphous silicon layers can be efficiently enhanced through a controlled periodic patterning. Light is trapped through coupling with photonic Bloch modes of the periodic structures, which act as an absorbing planar photonic crystal. We theoretically demonstrate this absorption enhancement through one or two dimensional patterning, and show the experimental feasibility through large area holographic patterning. Numerical simulations show over 50% absorption enhancement over the part of the solar spectrum comprised between 380 and 750nm. It is experimentally confirmed by optical measurements performed on planar photonic crystals fabricated by laser holography and reactive ion etching.

Daif, O El; Gomard, G; Meng, X; Kaminski, A; Fave, A; Lemiti, M; Caurel, E Garcia; Cabarrocas, P Roca i; Ahn, S; Jeon, H; Seassal, C; 10.1117/12.854035

2010-01-01

241

Piston-rotaxanes as molecular shock absorbers.  

PubMed

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. PMID:20158174

Sevick, E M; Williams, D R M

2010-04-20

242

Treatment of the common cold.  

PubMed

The common cold is a viral illness that affects persons of all ages, prompting frequent use of over-the-counter and prescription medications and alternative remedies. Treatment focuses on relieving symptoms (e.g., cough, nasal congestion, rhinorrhea). Dextromethorphan may be beneficial in adults with cough, but its effectiveness has not been demonstrated in children and adolescents. Codeine has not been shown to effectively treat cough caused by the common cold. Although hydrocodone is widely used and has been shown to effectively treat cough caused by other conditions, the drug has not been studied in patients with colds. Topical (intranasal) and oral nasal decongestants have been shown to relieve nasal symptoms and can be used in adolescents and adults for up to three days. Antihistamines and combination antihistamine/decongestant therapies can modestly improve symptoms in adults; however, the benefits must be weighed against potential side effects. Newer nonsedating antihistamines are ineffective against cough. Topical ipratropium, a prescription anticholinergic, relieves nasal symptoms in older children and adults. Antibiotics have not been shown to improve symptoms or shorten illness duration. Complementary and alternative therapies (i.e., Echinacea, vitamin C, and zinc) are not recommended for treating common cold symptoms; however, humidified air and fluid intake may be useful without adverse side effects. Vitamin C prophylaxis may modestly reduce the duration and severity of the common cold in the general population and may reduce the incidence of the illness in persons exposed to physical and environmental stresses. PMID:17323712

Simasek, Madeline; Blandino, David A

2007-02-15

243

Mathematical modeling of cold cap  

SciTech Connect

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.

Pokorny, Richard; Hrma, Pavel R.

2012-10-13

244

Mathematical modeling of cold cap  

NASA Astrophysics Data System (ADS)

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 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.

Pokorny, Richard; Hrma, Pavel

2012-10-01

245

Spectroscopy with cold and ultra-cold neutrons  

E-print Network

We present two new types of spectroscopy methods for cold and ultra-cold neutrons. The first method, which uses the \\RB drift effect to disperse charged particles in a uniformly curved magnetic field, allows to study neutron $\\beta$-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.

Hartmut Abele; Tobias Jenke; Gertrud Konrad

2014-12-16

246

Voltage-dependent absorbance change of carotenoids in halophilic archaebacteria.  

PubMed

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. PMID:8865818

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

1996-10-01

247

Is it a Cold or the Flu? -Know the Difference Signs & Symptoms Cold Flu  

E-print Network

Is it a Cold or the Flu? - Know the Difference Signs & Symptoms Cold Flu Onset Gradual Sudden Fever.rochester.edu/uhs (Check Care for Colds & Flu in "Health Topics.") Centers for Disease Control www.cdc.gov/flu University

Mahon, Bradford Z.

248

COLD-SAT dynamic model  

NASA Technical Reports Server (NTRS)

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.

Adams, Neil S.; Bollenbacher, Gary

1992-01-01

249

Electrical tree initiation in polyethylene absorbing Penning gas  

SciTech Connect

Ac tree initiation voltage was examined in untreated LDPE, vacuum degassed LDPE and LDPE absorbing He gas (He gas was absorbed after vacuum degassing). The authors have already reported that vacuum degassed LDPE shows much higher tree initiation voltage than untreated one because of absence of oxygen. Therefore they expected that LDPE absorbing He shows the same property with vacuum degassed LDPE. However tree initiation voltage of LDPE absorbing He is as low as that of untreated LDPE. LDPE absorbing Ar gas shows the same tendency. He or Ar gas does not change so much impulse tree initiation voltage. LDPE absorbing He was not well dyed with methylene blue after ac voltage application, which indicates that active oxidation does not occur. Low ac tree initiation voltage in LDPE absorbing He or Ar may be caused by Penning ionization in free volume.

Shimizu, N.; Tohyama, N.; Sato, H. [Nagoya Univ. (Japan). Dept. of Electrical Engineering

1996-12-31

250

Container and method for absorbing and reducing hydrogen concentration  

DOEpatents

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.

Wicks, George G. (Aiken, SC); Lee, Myung W. (North Augusta, SC); Heung, Leung K. (Aiken, SC)

2001-01-01

251

Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint  

SciTech Connect

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.

Stynes, J. K.; Ihas, B.

2012-04-01

252

Determination of decay coefficients for combustors with acoustic absorbers  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

253

Smart skin spiral antenna with chiral absorber  

NASA Astrophysics Data System (ADS)

Recently there has been considerable interest toward designing 'smart skins' for aircraft. The smart skin is a composite layer which may contain conformal radars, conformal microstrip antennas or spiral antennas for electromagnetic applications. These embedded antennas will give rise to very low radar cross section (RCS) or can be completely 'hidden' to tracking radar. In addition, they can be used to detect, monitor or even jam other unwanted electromagnetic field signatures. This paper is designed to address some technical advances made to reduce the size of spiral antennas using tunable dielectric materials and chiral absorbers. The purpose is to design, develop and fabricate a thin, wideband, conformal spiral antenna architecture that is structurally integrable and which uses advanced Penn State dielectric and absorber materials to achieve wideband ground planes, and together with low RCS. Traditional practice has been to design radome and antenna as separate entities and then resolve any interface problems during an integration phase. A structurally integrable conformal antenna, however, demands that the functional components be highly integrated both conceptually and in practice. Our concept is to use the lower skin of the radome as a substrate on which the radiator can be made using standard photolithography, thick film or LTCC techniques.

Varadan, Vijay K.; Varadan, Vasundara V.

1995-05-01

254

Erbium concentration dependent absorbance in tellurite glass  

NASA Astrophysics Data System (ADS)

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 Er3+ 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 4F7/2, 2H11/2, 4F9/2, 4I9/2, 2H11/2 and 4I13/2, respectively. The results are analyzed by means of optical band gap Eg and Urbach energy Eu. 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 Er2O3 concentration from 0 to 1.5 mol%. The excellent absorbance of the prepared tellurite glasses makes them suitable for fabricating solid state lasers.

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

2014-09-01

255

Metamaterial perfect absorber based hot electron photodetection.  

PubMed

While the nonradiative decay of surface plasmons was once thought to be only a parasitic process that limits the performance of plasmonic devices, it has recently been shown that it can be harnessed in the form of hot electrons for use in photocatalysis, photovoltaics, and photodetectors. Unfortunately, the quantum efficiency of hot electron devices remains low due to poor electron injection and in some cases low optical absorption. Here, we demonstrate how metamaterial perfect absorbers can be used to achieve near-unity optical absorption using ultrathin plasmonic nanostructures with thicknesses of 15 nm, smaller than the hot electron diffusion length. By integrating the metamaterial with a silicon substrate, we experimentally demonstrate a broadband and omnidirectional hot electron photodetector with a photoresponsivity that is among the highest yet reported. We also show how the spectral bandwidth and polarization-sensitivity can be manipulated through engineering the geometry of the metamaterial unit cell. These perfect absorber photodetectors could open a pathway for enhancing hot electron based photovoltaic, sensing, and photocatalysis systems. PMID:24837991

Li, Wei; Valentine, Jason

2014-06-11

256

Avionics Box Cold Plate Damage Prevention  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

257

Tautochronic centrifugal pendulum vibration absorbers. General design and analysis  

NASA Astrophysics Data System (ADS)

Since the 1930s, centrifugal pendulum vibration absorbers have been used in rotating and reciprocating machinery for the attenuation of torsional vibrations. A large variety of absorber types were suggested and the design was done by linearization theory until the introduction of the tautochronic bifilar pendulum absorbers. Since then, the performance and dynamic stability of this specific absorber type have been considered in analytical and numerical investigations. Different perturbations, e.g. nonlinear mistuning, were considered in order to optimize the system performance, but the characteristic bifilar design remained unchanged. In this paper, a general approach for the design of tautochronic pendulum vibration absorbers is proposed. As a result, it is possible to deal with a large variety of non-bifilar centrifugal vibration absorber designs which provide application-related optimal performance and resolve some of the existing design limitations. Established analytic predictions that show a satisfactory agreement with numerical as well as experimental investigations for bifilar absorbers are not applicable for the comparison of different tautochronic absorbers. Therefore, the second part of this work shows how to analyze this class of centrifugal vibration absorbers using a Hamiltonian formulation. Successive canonical transformations lead to nonlinear equations in action-angle variables, which are then approximated to first order and analyzed by using the method of averaging. These results provide a basis for the design and analysis of tautochronic bifilar and non-bifilar vibration absorbers.

Mayet, J.; Ulbrich, H.

2014-02-01

258

Images of the Cold War.  

ERIC Educational Resources Information Center

The conventional U.S. picture traces the Cold War to Soviet violation of wartime agreements, while the U.S.S.R. defends its actions as responses to American violations and foreign adventurism. An understanding of how ideology is shaped by national self-interest will help students see beyond propaganda and myth in interpreting past and current…

Chomsky, Noam

1989-01-01

259

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...

260

Hot, Cold, Fresh and Salty  

NSDL National Science Digital Library

In this activity, learners observe the effects of the layering of warm and cold water and water that is more or less saline than regular water. They will discover how the effects of salinity and temperature are the root cause of thermohaline layering in the ocean.

Roth, Jerry; Service, Noaa O.

261

Complement, cold agglutinins, and therapy.  

PubMed

In this issue of Blood, Shi and coworkers show that TNT003, a mouse monoclonal antibody targeting complement protein C1s, prevents induction of in vitro hemolysis by cold agglutinins (CA). If successfully transferred into the clinical setting by further studies, these findings may result in a novel therapeutic principle for a frequently difficult problem. PMID:24970929

Berentsen, Sigbjørn

2014-06-26

262

Hybrid vibration absorber with virtual passive devices  

NASA Astrophysics Data System (ADS)

A vibration control scheme integrating a passive mass-spring resonator and a linear actuator is developed. A control algorithm is devised to convert the actuator into an additional set of virtual mass-spring structure of programmable characteristic frequency. The relative motion between the primary body and the reaction mass is measured, as well as the acceleration of the reaction mass. This hybrid dynamic vibration absorber is capable of neutralizing a harmonic disturbance regardless of the detailed dynamics of the primary structure and other passive elements. Stability analysis leads to a simple, explicit stability criterion. Distribution of the counter-disturbance force between the active and passive devices is analyzed, and the transient performance is also investigated. Real-time experiments as well as numerical simulations are conducted to confirm the effectiveness of the proposed scheme.

Wu, Shang-Teh; Chiu, Yea-Ying; Yeh, Yuan-Chih

2007-01-01

263

Novel active vibration absorber with magnetorheological fluid  

NASA Astrophysics Data System (ADS)

Disturbing vibrations diminish the performance of technical high precision devices significantly. In search of a suitable solution for reducing these vibrations, a novel concept of active vibration reduction was developed which exploits the special properties of magnetorheological fluids. In order to evaluate the concept of such an active vibration absorber (AVA) a demonstrator was designed and manufactured. This demonstrator generates a force which counteracts the motion of the vibrating body. Since the counterforce is generated by a centrifugal exciter, the AVA provides the capability to compensate vibrations even in two dimensions. To control the strength of the force transmitted to the vibrating body, the exciter is based on a tunable MR coupling. The AVA was integrated in an appropriate testing device to investigate its performance. The recorded results show a significant reduction of the vibration amplitudes by an order of magnitude.

Gerlach, T.; Ehrlich, J.; Böse, H.

2009-02-01

264

Porous Carbon Nanoparticle Networks with Tunable Absorbability  

PubMed Central

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

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

2013-01-01

265

Porous Carbon Nanoparticle Networks with Tunable Absorbability  

NASA Astrophysics Data System (ADS)

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.

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

2013-08-01

266

Screening EUV mask absorbers for defect repair  

NASA Astrophysics Data System (ADS)

Five EUV film stacks were prepared and evaluated from the multiple viewpoints of mask repair process: etching property, CD control and wafer print. Etching property results revealed a thicker lower reflective (LR) layer stack showed good performance. Some types of defects were repaired and a CD comparison done with both CD-SEM and EUV microscope. It was found thinner total film stack (LR plus absorber) performs better than thicker ones for CD control. In addition, thicker LR performed better than thinner LR. Wafer print performance on the repaired site was evaluated through focus by imaging on an EUV microscope. Wafer printability performance showed that thinner total film stack performed better than a thicker one. Finally the best stack for EUV mask repair performance was determined to be a thinner total film stack and thicker a LR from all the various points of view.

Isogawa, Takeshi; Seki, Kazunori; Lawliss, Mark; Gallagher, Emily; Akima, Shinji; Konishi, Toshio

2014-07-01

267

Strength function under the absorbing boundary condition  

NASA Astrophysics Data System (ADS)

The strength function of the linear response by the external field is calculated in the formalism of the absorbing boundary condition (ABC). The dipole excitation of a schematic two-body system is treated in the present study. The extended completeness relation, which is assumed on the analogy of the formulation in the complex scaling method (CSM), is applied to the calculation of the strength function. The calculation of the strength function is successful in the present formalism and hence, the extended completeness relation seems to work well in the ABC formalism. The contributions from the resonance and the non-resonant continuum is also analyzed according to the decomposition of the energy levels in the extended completeness relation.

Iwasaki, M.; Otani, R.; Ito, M.

2014-12-01

268

Absorbed doses from temporomandibular joint radiography  

SciTech Connect

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.

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

1985-06-01

269

Tips to Protect Workers in Cold Environments  

MedlinePLUS

... Anti-Retaliation Tips To Protect Workers In Cold Environments Prolonged exposure to freezing or cold temperatures may ... Tips include: How to Protect Workers Recognize the environmental and workplace conditions that may be dangerous. Learn ...

270

Vitamin C and the Common Cold Revisited.  

ERIC Educational Resources Information Center

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)

Travis, H. Richard

1984-01-01

271

Common cold - how to treat at home  

MedlinePLUS

... Antibiotics are almost never needed to treat a common cold. Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) help lower ... Many home remedies are popular treatments for the common cold. These include vitamin C, zinc supplements, and Echinacea. ...

272

Rotor blade lag damping using embedded chordwise absorbers  

NASA Astrophysics Data System (ADS)

The feasibility of helicopter blade lag damping using embedded chordwise absorbers is investigated. The basic feature of this approach is the use of tuned vibration absorbers along the blades. This concept, utilizing a portion of the leading edge weights that are already incorporated into the blade as a part of the mass of the absorbers, may have the potential to replace current blade lag dampers and reduce complexity, aerodynamic drag, and weight. The effectiveness of the embedded absorbers is evaluated by analyzing and testing blade lag damping and rotor system aeromechanical stability. An aeromechanical stability analysis of the rotor system with embedded chordwise absorbers is developed. The rotor blade is modeled as an elastic beam undergoing axial, flapwise, lagwise, and torsional deflections. The fuselage is modeled as a rigid body with roll and pitch rotations about its center of mass. Each embedded absorber is modeled as a mass-spring pair. The rotor-absorber-fuselage system equations of motion are formulated using Hamilton's Principle and spatially discretized using the finite element method. The modal frequencies and damping of the system are found using complex eigenvalue solutions of the linearized equations. A rigid blade-absorber model is developed to explore the dynamic response of the embedded absorbers, including the static and steady-state dynamic response, and to examine the effect of the embedded absorber on rotor blade aeroelastic stability, including flap-lag flutter, pitch-flap flutter, and pitch divergence. A small-scale model rotor system with embedded absorbers is designed and constructed. A set of experiments measuring blade lag frequency and damping is conducted. The effects of some key issues, including absorber mass, location, and tuning frequency, are examined experimentally. The analytical results are correlated with the experimental data. The theoretical lag frequencies and damping of the blade with embedded absorbers are in good agreement with the experimental data. The aeromechanical stability analysis of the rotor-fuselage system also shows a good agreement with the experimental data. The theoretical and experimental results both show promising blade lag damping augmentation using embedded chordwise absorbers. The blade damping augmentation using embedded chordwise absorber varies from 0.3% to 15% critical damping ratio, depending on blade and absorber parameters. The ground resonance stability analysis of the hingeless rotor system and articulated rotor system shows that the blade lag damping augmentation using embedded chordwise absorbers improves the ground resonance stability. (Abstract shortened by UMI.)

Kang, Hao

273

Two-Photon Cooperative Absorption in Colliding Cold Na Atoms  

NASA Astrophysics Data System (ADS)

Two-photon cooperative absorption is common in solid-state physics. In a sample of trapped cold atoms, this effect may open up new possibilities for the study of nonlinear effects. The experiment described herein starts with two colliding Na atoms in the S hyperfine ground state. The pair absorb two photons, resulting in both a P1/2 and a P3/2 atom. This excitation is observed by ionization using an external light source. A simple model that considers only dipole-dipole interactions between the atoms allows us to understand the basic features observed in the experimental results. Both the pair of generated atoms and the photons originating from their decay are correlated and may have interesting applications that remain to be explored.

Pedrozo-Peñafiel, E.; Paiva, R. R.; Vivanco, F. J.; Bagnato, V. S.; Farias, K. M.

2012-06-01

274

The cold equation of state of tantalum  

SciTech Connect

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.

Greeff, Carl W [Los Alamos National Laboratory; Rudin, Sven P [Los Alamos National Laboratory; Corckett, Scott D [Los Alamos National Laboratory; Wills, John M [Los Alamos National Laboratory

2009-01-01

275

Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

276

Absorbing boundaries in the mean-field approximation  

SciTech Connect

Absorbing boundaries in the mean-field approximation are investigated and applied to small systems interacting with strong laser fields. Two types of calculations are considered: (i) a variational approach with a complex absorbing potential included in the full Hamiltonian and (ii) the inclusion of a complex absorbing potential in the single-particle equations. It is elucidated that the second approach outperforms the variational approach for small grids.

Jhala, Chirag; Dreissigacker, Ingo; Lein, Manfred [Institut fuer Theoretische Physik and Centre for Quantum Engineering and Space-Time Research (QUEST), Leibniz Universitaet Hannover, Appelstrasse 2, D-30167 Hannover (Germany)

2010-12-15

277

Refractory plasmonics with titanium nitride: broadband metamaterial absorber.  

PubMed

A high-temperature stable broadband plasmonic absorber is designed, fabricated, and optically characterized. A broadband absorber with an average high absorption of 95% and a total thickness of 240 nm is fabricated, using a refractory plasmonic material, titanium nitride. This absorber integrates both the plasmonic resonances and the dielectric-like loss. It opens a path for the interesting applications such as solar thermophotovoltaics and optical circuits. PMID:25327161

Li, Wei; Guler, Urcan; Kinsey, Nathaniel; Naik, Gururaj V; Boltasseva, Alexandra; Guan, Jianguo; Shalaev, Vladimir M; Kildishev, Alexander V

2014-12-01

278

Effect of finite absorber dimensions on ?-ray attenuation measurements  

NASA Astrophysics Data System (ADS)

Using 137Cs ? rays, the effect of finite absorber dimensions on attenuation measurements has been studied. Copper and mercury targets were used. Absorber dimensions up to five mean free paths were used. A correlated effect was observed in the measurements due to absorber thickness and its dimensions in the transverse directions. The values of the attenuation coefficients for copper and mercury have also been determined.

Varier, K. M.; Kunju, S. Nasiruddeen; Madhusudanan, K.

1986-04-01

279

Cold vs. Flu Know the Difference  

E-print Network

Cold vs. Flu Know the Difference Symptoms Cold Flu Fever Rare Usual ­ can be 100 to 102or higher can help prevent the spread of colds or flu F � KEEP YOUR HANDS CLEAN ­ Wash with soap and water. � STAY HOME WHEN SICK � GET VACCINATED FOR FLU Getting a flu shot or the nasal spray every year

Burke, Peter

280

Vitamin C and the common cold  

Microsoft Academic Search

The effect of vitamin C on the common cold has been the subject of several studies. These studies do not support a considerable decrease in the incidence of the common cold with supplemental vitamin C. However, vitamin C has consistently decreased the duration of cold episodes and the severity of symptoms. The benefits that have been observed in different studies

Harri Hemilä

1992-01-01

281

Optimal active vibration absorber - Design and experimental results  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

282

Optimal active vibration absorber: Design and experimental results  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

283

Directional self-supporting pyramid shaped hot water solar absorber  

SciTech Connect

A solar absorber to be mounted on the roofs of buildings, the absorber having the form of a pyramid with the heat absorbing elements mounted across the upward extending faces of the pyramid and the base formed to conform to the contour of the roof so that the solar absorber may be fixedly mounted on the roof of a building. In a modified form of my invention each face of the pyramid is independently equipped with a heat sensor which is electrically connected to a water valve and water circulator so that water circulates only through the faces exposed to sunlight.

Tornquist, A.

1980-01-22

284

Cold dark matter heats up.  

PubMed

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 ?CDM paradigm, the remaining 95 per cent consists of dark energy (?) and cold dark matter. ?CDM 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. PMID:24522596

Pontzen, Andrew; Governato, Fabio

2014-02-13

285

Cold dark matter heats up  

NASA Astrophysics Data System (ADS)

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 ?CDM paradigm, the remaining 95 per cent consists of dark energy (?) and cold dark matter. ?CDM 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.

Pontzen, Andrew; Governato, Fabio

2014-02-01

286

Ultra-cold molecule production.  

SciTech Connect

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.

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

2005-12-01

287

Hot Topics in Cold Gases  

E-print Network

Since the first experimental realization of Bose-Einstein condensation in cold atomic gases in 1995 there has been a surge of activity in this field. Ingenious experiments have allowed us to probe matter close to zero temperature and reveal some of the fascinating effects quantum mechanics has bestowed on nature. It is a challenge for mathematical physicists to understand these various phenomena from first principles, that is, starting from the underlying many-body Schr\\"odinger equation. Recent progress in this direction concerns mainly equilibrium properties of dilute, cold quantum gases. We shall explain some of the results in this article, and describe the mathematics involved in understanding these phenomena. Topics include the ground state energy and the free energy at positive temperature, the effect of interparticle interaction on the critical temperature for Bose-Einstein condensation, as well as the occurrence of superfluidity and quantized vortices in rapidly rotating gases.

Robert Seiringer

2009-08-25

288

Cold cathode vacuum discharge tube  

DOEpatents

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.

Boettcher, Gordon E. (Albuquerque, NM)

1998-01-01

289

Hot and Cold Ideal Gases  

NSDL National Science Digital Library

The EJS Hot and Cold Ideal Gases model simulates the mixing of hot and cold two-dimensional ideal gases in a square box. This simulation can be used as part of the activity described in "The Statistical Interpretation of Entropy: An Activity" by Todd Timberlake, to be published in The Physics Teacher. In the model, one gas is initially confined to the left side of the box while the other gas is confined to the right side. An animation window shows the motion of the particles in the box, while an optional graph window plots the temperature of each side of the box, which is determined by measuring the average KE of the particles on each side. The initial number of particles and temperature on each side of the square can be changed and a button allows the user to reverse the particle velocities at any time. The user can modify this simulation if EJS is installed locally by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. EJS Hot and Cold Ideal Gases model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_entropy_HotAndColdIdealGases.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional EJS models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or EJS.

Timberlake, Todd

2010-07-01

290

Cold Atoms and Maxwell's Demon  

NASA Astrophysics Data System (ADS)

Recent experiments have focused on realizing and studying asymmetric potential barriers for ultracold atoms. Practically speaking, asymmetric barriers, or "atomtronic diodes", open up newmethods for controlling cold atoms, and possibly methods for laser cooling atoms and molecules that are not amenable to present laser-cooling techniques. More fundamentally, asymmetric barriers are interesting as realizations of the textbook statistical-mechanics scenario of Maxwell's demon. This chapter reviews experimental progress in this area, as well as some related practical and theoretical issues.

Steck, Daniel A.

2013-12-01

291

Acclimatization to cold in humans  

NASA Technical Reports Server (NTRS)

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.

Kaciuba-Uscilko, Hanna; Greenleaf, John E.

1989-01-01

292

Microwave absorbing properties and structural design of microwave absorbers based on polyaniline and polyaniline/magnetite nanocomposite  

NASA Astrophysics Data System (ADS)

Double-layer absorbers with enhanced microwave absorbing properties were designed based on polyaniline and polyaniline/magnetite composite with a total thickness of 1 mm. The double-layer microwave absorbers have better microwave absorbing properties than those of single-layer microwave absorbers, and the microwave absorbing properties of the double-layer structure are influenced by the coupling interactions between the absorbing layer and matching layer. When the absorbing layer is PANI with a thickness of 0.4 mm, and the matching layer is PANI/Fe3O4 composite with a thickness of 0.6 mm, the minimum reflection loss (RL) reaches -42 dB at 29.27 GHz and the absorption bandwidth with RL below -10 dB is about 11.8 GHz. While when PANI and PANI/Fe3O4 composite are acted as matching layer and absorbing layer, respectively, with the same thickness of 0.5 mm, a minimum RL value of -54 dB is observed at 33.72 GHz and the absorption bandwidth is about 11.28 GHz ranging from 27.24 to 38.52 GHz with the RL value below -10 dB.

Xu, Fenfang; Ma, Li; Huo, Qisheng; Gan, Mengyu; Tang, Jihai

2015-01-01

293

The COLD-SAT program  

NASA Technical Reports Server (NTRS)

The Cryogenic On-Orbit Liquid Depot Storage, Acquisition and Transfer (COLD-SAT) satellite is an experimental spacecraft launched from an expendable launch vehicle which is designed to investigate the systems and technologies required for efficient and reliable management of cryogenic fluid in the reduced-gravity space environment. Future applications such as Space Station, Space Transportation Vehicle (STV), external tank (ET), aft cargo carrier (ACC) propellant scavenging, storage depots, and lunar and interplanetary missions, among others, have provided the impetus to pursue this technology in a timely manner to support the design efforts. A refined conceptual approach has been developed and an overview of the COLD-SAT program is described which includes the following: (1) a definition of the technology needs and the accompanying experimental six-month baseline mission; (2) a description of the experiment subsystem, major features, and rationale for satisfaction of primary and secondary experiment requirements using LH2 as the test fluid; and (3) a presentation of the conceptual design of the COLD-SAT spacecraft subsystems which support the on-orbit experiment with emphasis on those areas which posed the greatest technical challenge.

Bailey, William J.

1990-01-01

294

Micro-Kelvin cold molecules.  

SciTech Connect

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.

Strecker, Kevin E.; Chandler, David W.

2009-10-01

295

Long pathlength, three-dimensional absorbance microchip.  

PubMed

A long pathlength, three-dimensional U-type flow cell was microfabricated and evaluated for improved absorbance detection on a glass microdevice. A small diameter hole (75mum) was laser etched in a thin glass substrate whose thickness (100mum) defined much of the pathlength of the cell. This substrate was thermally bonded and sandwiched between two different glass substrates. The top substrate contained a typical injection cross and separation microchannel. Projecting out of the plane of the separation device was a 126mum pathlength flow cell as defined by the laser etched hole and the attached microchannels. The flow cell was connected to a microchannel on the bottom substrate that led to a waste reservoir. The planar, flat windows on the top and bottom of this device made light introduction and collection a simple matter using a light emitting diode (LED) and microscope objective. The experimentally obtained detection limit for rhodamine B was determined to be 0.95muM, which is nearly identical to the theoretical limit calculated by Beer's Law. A separation of three fluorescent dyes was performed, and direct comparisons were made between the transmittance changes through the narrow pathlength separation microchannel and the adjacent long pathlength, three-dimensional U-type flow cell. PMID:19071618

Collins, Greg E; Lu, Qin; Pereira, Nicholas; Wu, Peter

2007-04-15

296

Spacesuit Evaporator-Absorber-Radiator (SEAR)  

NASA Technical Reports Server (NTRS)

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.

Bue, Grant C.; Hodgson, Ed; Izenso, Mike; Chan, Weibo; Cupples, Scott

2011-01-01

297

Multifunctional Space Evaporator-Absorber-Radiator (SEAR)  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

298

Effectiveness of silane treatment on absorbable microfibers.  

PubMed

Preliminary experiments suggest pretreatment of absorbable crystalline, calcium-sodium-metaphosphate (CSM) microfibers with trimethoxy-based silane coupling agents yields a polysiloxane film barrier which protects the fiber surface from early dissolution due to water. Compared to thermoplastic poly(L-lactic acid) (PLLA) composites reinforced with untreated fibers, PLLA composites reinforced with a variety of silane pretreated microfibers showed increased mechanical properties, suggesting improved adhesion was achieved at the fiber/matrix interface. Unfortunately, the silane pretreated CSM/PLLA composite showed no increase in wet strength retention after short-term in vitro exposure. This may be due to plasticization from water entering the composite at areas of incomplete fiber wetting by the highly viscous molten PLLA. However, when a nonabsorbable, low viscosity unsaturated polyester thermoset resin was reinforced with methacryloxy-silane pretreated CSM microfibers, there was no decrease in flexural strength and less than a 10% decrease in flexural modulus after 7 days exposure to 7.4 pH Tris-buffered saline at 37 degrees C. PMID:10147714

Andriano, K P; Daniels, A U

1992-01-01

299

Light absorbing carbon emissions from commercial shipping  

NASA Astrophysics Data System (ADS)

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.

Lack, Daniel; Lerner, Brian; Granier, Claire; Baynard, Tahllee; Lovejoy, Edward; Massoli, Paola; Ravishankara, A. R.; Williams, Eric

2008-07-01

300

Physiological characteristics of cold acclimatization in man  

NASA Astrophysics Data System (ADS)

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.

Mathew, Lazar; Purkayastha, S. S.; Jayashankar, A.; Nayar, H. S.

1981-09-01

301

Cold Pools in the Columbia Basin  

SciTech Connect

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.

Whiteman, Charles D.; Zhong, Shiyuan; Shaw, William J.; Hubbe, John M.; Bian, Xindi; Mittelstadt, J.

2001-01-01

302

21 cm HI Absorber in the Outer Disk & Halos of Galaxies  

NASA Astrophysics Data System (ADS)

We present 21cm HI radio observations of foreground galaxy and background radio bright QSO pairs with extremely small projected distances. In particular I'll discuss our pilot project where we studied such a pair with projected distance of 2.5" (=1.7 kpc in galaxy rest frame) in detail using three NRAO facilities - the GBT, the VLA, and the VLBA. We detected a 21 cm HI absorber of column density ? 3.39 (± 0.11) × 1019 cm-2 at the redshift of the foreground galaxy. The HI absorber was found to be dynamically similar to a single quiescent cloud and was consistent with the cold neutral medium (CNM) found in the ISM of galaxies. The foreground galaxy is a low luminosity spiral with a low star-formation surface density of 0.001 Mo yr-1 kpc-2 . This galaxy remains undetected in HI emission, thus suggesting that while there are pockets of high column density gas, the total HI associated with the system is quite low.

Borthakur, Sanchayeeta; Tripp, T.; Yun, M. S.

2010-01-01

303

HOM absorbers for ERL cryomodules at BNL  

SciTech Connect

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.

Hahn,H.; Ben-Zvi, I.; Hammons, L.; Xu, W.

2009-09-20

304

TOPOLOGICAL CONDITIONS FOR THE EXISTENCE OF ABSORBING CANTOR SETS  

E-print Network

is to generalize the results of [BKNS]: We want to indicate which topological constraints allowTOPOLOGICAL CONDITIONS FOR THE EXISTENCE OF ABSORBING CANTOR SETS Henk Bruin Abstract. This paper that very general topological conditions are given that either i) guarantee the existence of an absorbing

Bruin, Henk

305

Coupling of an Absorber to a Polarization-Sensitive Antenna  

E-print Network

Coupling of an Absorber to a Polarization-Sensitive Antenna Amol Upadhye Department of Physics a polarization- sensitive antenna may couple to the antenna, preferentially absorbing electro- magnetic waves of the polarization radiated by the antenna. Lock-in amplifica- tion techniques were used to compare the response

306

Optimization of electric shunt resonant circuits for electroacoustic absorbers  

E-print Network

Optimization of electric shunt resonant circuits for electroacoustic absorbers H. Lissek, R issue is to properly design an electrical matching circuit which, when connected across the transducer as an absorber/reflector of sound, and the electric terminals of which are connected to a dedicated electric load

Paris-Sud XI, Université de

307

Performance Simulation of Pyramidal and Wedge Microwave Absorbers  

Microsoft Academic Search

Anechoic chambers signal absorption capability is directly correlated to its performance. One of the main components in enabling signal absorption is the design and material used in designing the absorbers. Two of the main types are pyramidal and wedge-shaped ones. In this work, truncated pyramidal and truncated wedge absorbers for anechoic chamber application have been designed to operate effectively in

H. Nornikman; Ping Jack Soh; Abdullah Al-hadi Azremi; M. S. Anuar

2009-01-01

308

Absorbed substrate fermentation for pectinase production with Aspergillus niger  

Microsoft Academic Search

A 130 litre packed-bed bioreactor was used for pectinase production with Aspergillus niger using absorbed substrate fermentation techniques. Pectinolytic enzyme activity and relative CO2 production were used as indicators of metabolic activity. Absorbed substrate fermentation is an efficient process for pectinase production and is also an interesting model because the culture medium, water, nutrients and specific inducers, can be designed

S. Huerta; E. Favela; R. López-Ulibarri; A. Fonseca; G. Viniegra-González; M. Gutiérrez-Rojas

1994-01-01

309

Adaptive Tuned Vibration Absorber based on Magnetorheological Elastomer  

Microsoft Academic Search

This study presents an adaptive tuned vibration absorber (ATVA) which is based on magnetorheological elastomer (MRE). Traditional dynamic absorber has limited its application and vibration absorption capacity for its narrow working frequency bandwidth. MRE is a kind of smart material whose modulus can be controlled by applied magnetic field. Based on MREs, an ATVA which works on shear mode is

H. X. Deng; X. L. Gong

2007-01-01

310

Science on a Roll. Part One: Absorbing Inquiry.  

ERIC Educational Resources Information Center

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)

Brendzel, Sharon

2002-01-01

311

21 CFR 868.5300 - Carbon dioxide absorbent.  

Code of Federal Regulations, 2013 CFR

A carbon dioxide absorbent is a device intended for medical purposes that consists of an absorbent material (e.g., soda lime) that is intended to remove carbon dioxide from the gases in the breathing circuit. (b) Classification. Class I (general...

2013-04-01

312

21 CFR 868.5310 - Carbon dioxide absorber.  

Code of Federal Regulations, 2013 CFR

A carbon dioxide absorber is a device that is intended for medical purposes and that is used in a breathing circuit as a container for carbon dioxide absorbent. It may include a canister and water drain. (b) Classification. Class I (general...

2013-04-01

313

Properties of absorbed dose distribution in heterogeneous media  

Microsoft Academic Search

Accuracy of calculation of the absorbed dose spatial distribution into patient body is an important task in the radiation treatment of cancer. The correct calculation determines radiotherapy effectiveness. Thus, researches are improving calculation methods permanently to achieve running speed and accuracy increasing of used algorithms of calculation routines. The algorithms of routines for calculations of absorbed dose radial distributions into

A G Kondratjeva; A M Kolchuzhkin; V A Lisin; I S Tropin

2006-01-01

314

An Absorbing Look at Terry-Cloth Towels  

ERIC Educational Resources Information Center

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…

Moyer, Richard; Everett, Susan

2010-01-01

315

Flexible metamaterial absorbers for stealth applications at terahertz frequencies  

E-print Network

Flexible metamaterial absorbers for stealth applications at terahertz frequencies Krzysztof: We have wrapped metallic cylinders with strongly absorbing metamaterials. These resonant structures of the reflection spectrum of the metamaterial. ©2011 Optical Society of America OCIS codes: (110.6795) Terahertz

Zhang, Xin

316

CFRP-based broad-band Radar Absorbing Materials  

Microsoft Academic Search

Strong interest in radar absorbing materials (RAMs) took place with years due to their extensive sectors of application. RAMs are coatings whose electric and magnetic properties allow the absorption of microwave energy over certain frequencies. In particular, RAMs are very effective means of Radar Cross Section (RCS) reduction in the context of stealth technology. RCS reduction requires absorbers with broad-band

C. Mitrano; A. Balzano; M. Bertacca; M. Flaccavento; R. Mancinelli

2008-01-01

317

Solar concentrators with maximal concentration for cylindrical absorbers  

Microsoft Academic Search

The differential equation is derived that describes the reflector of an ideal two-dimensional radiation concentrator with an absorber of arbitrary convex shape. For the special case of an absorber with circular cross section, the equation can be solved in closed form if suitable coordinates are used. The effect of absorption at the reflector is considered, and formulas are presented for

Ari Rabl

1976-01-01

318

Performance of an artificial absorber for truncating FEM meshes  

NASA Technical Reports Server (NTRS)

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.

Gong, Jian; Volakis, John L.

1995-01-01

319

Revealing the Properties of Mg II Absorbing Galaxies at z > 1 with HST WFC3/IR  

NASA Astrophysics Data System (ADS)

Intervening absorption from Mg II in the spectra of distant quasars is understood to trace the tidal stripping, accretion and outflows of cold, enriched gas in the circumgalactic medium of galaxies, independent of luminosity, to high redshift. Tens of thousands of Mg II absorbers in the range 0.3 < z < 2.2 have been extracted to date from the SDSS spectroscopic quasar sample, but their utility in aiding our understanding of the gaseous processes driving galaxy evolution has been hindered by the observational difficulties of detecting their host galaxies at intermediate and high redshifts and at small angular separations from brighter background quasars. We present first results from an 18-orbit HST Cycle 21 WFC3/IR program, which has obtained direct imaging and grism observations of galaxies in the fields surrounding the 9 quasar sight lines in the SDSS with the highest frequency of uncorrelated foreground Mg II absorption in the range 0.7< z < 2.2. These highly efficient observations include 56 Mg II absorbers, most all of which are matched unambiguously to galaxies in the grism data, thereby doubling the number of spectroscopically confirmed Mg II absorbing galaxies at z > 1. The data further enable precise measurements of the impact parameters, morphologies, inclination angles, star formation rates, and star formation rate surface densities of typical Mg II-selected galaxies, as a function of Mg II absorption strength, which are complete for a large range in projected separations (7-450 kpc) and to low star formation rates (~1.3 Msun/yr).

Lundgren, Britt; Brammer, Gabriel; York, Donald G.; Chisholm, John P.; Erb, Dawn; Kulkarni, Varsha P.; Straka, Lorrie; Tremonti, Christina A.; Van Dokkum, Pieter G.; Wake, David

2015-01-01

320

Performance evaluation of CFRP-rubber shock absorbers  

SciTech Connect

In the present work a numerical investigation on the energy absorbing capability of dedicated structural components made of a carbon fiber reinforced polymer and an emulsion polymerised styrene butadiene rubber is reported. The shock absorbers are devices designed to absorb large amounts of energy by sacrificing their own structural integrity. Their aim is to cushion the effects of an impact phenomenon with the intent to preserve other structures from global failure or local damaging. Another important role of shock absorbers is reducing the peak of the acceleration showed during an impact phenomenon. This effect is of considerable interest in the case of vehicles to preserve passengers’ safety. Static and dynamic numerical results are compared with experimental ones in terms of mean crushing forces, energy and peak crushing. The global performance of the absorbers has been evaluated by referencing to a proposed quality index.

Lamanna, Giuseppe, E-mail: giuseppe.lamanna@unina2.it; Sepe, Raffaele, E-mail: giuseppe.lamanna@unina2.it [Department of Industrial and Information Engineering, Second University of Naples, via Roma, 29 - 81031 Aversa (Italy)

2014-05-15

321

Thermally Induced Nonlinear Optical Absorption in Metamaterial Perfect Absorbers  

E-print Network

A metamaterial perfect absorber consisting of a tri-layer (Al/ZnS/Al) metal-dielectric-metal system with top aluminium nano-disks is fabricated by laser-interference lithography and lift-off processing. The metamaterial absorber had peak resonant absorbance at 1090 nm and showed nonlinear absorption for 600ps laser pulses at 1064 nm wavelength. A nonlinear saturation of reflectance was measured to be dependent on the average laser power incident and not the peak laser intensity. The nonlinear behaviour is shown to arise from the heating due to the absorbed radiation and photo-thermal changes in the dielectric properties of aluminium. The metamaterial absorber is seen to be damage resistant at large laser intensities of 25 MW/cm2.

Guddala, Sriram; Ramakrishna, S Anantha

2015-01-01

322

Towards absorbing outer boundaries in General Relativity  

E-print Network

We construct exact solutions to the Bianchi equations on a flat spacetime background. When the constraints are satisfied, these solutions represent in- and outgoing linearized gravitational radiation. We then consider the Bianchi equations on a subset of flat spacetime of the form [0,T] x B_R, where B_R is a ball of radius R, and analyze different kinds of boundary conditions on \\partial B_R. Our main results are: i) We give an explicit analytic example showing that boundary conditions obtained from freezing the incoming characteristic fields to their initial values are not compatible with the constraints. ii) With the help of the exact solutions constructed, we determine the amount of artificial reflection of gravitational radiation from constraint-preserving boundary conditions which freeze the Weyl scalar Psi_0 to its initial value. For monochromatic radiation with wave number k and arbitrary angular momentum number l >= 2, the amount of reflection decays as 1/(kR)^4 for large kR. iii) For each L >= 2, we construct new local constraint-preserving boundary conditions which perfectly absorb linearized radiation with l analysis to a weakly curved background of mass M, and compute first order corrections in M/R to the reflection coefficients for quadrupolar odd-parity radiation. For our new boundary condition with L=2, the reflection coefficient is smaller than the one for the freezing Psi_0 boundary condition by a factor of M/R for kR > 1.04. Implications of these results for numerical simulations of binary black holes on finite domains are discussed.

Luisa T. Buchman; Olivier C. A. Sarbach

2006-09-16

323

The Stellar Continuum Light from Damped Lyman-alpha Absorber Galaxies Detected with Integral Field Spectroscopy  

NASA Astrophysics Data System (ADS)

A new challenge in galaxy evolution studies is to understand how gas flows in and out of galaxies through their circumgalactic medium (CGM). The best way to tackle this is to bring together data on cold gas, metals and stellar content of the same galaxies. Galaxies selected via the absorption they produce in the spectra of background quasars are a powerful tool to study the cold gas play a crucial role in this respect, but characterising the stellar content of these absorbers has proved to be challenging until now. Our group has used 3D spectroscopy at near-infrared wavelengths made possible by the SINFONI instrument on VLT, aided with adaptive optics (AO), to successfully detect 5 galaxies responsible for DLAs/sub-DLAs. For this sample, we have retrieved and analyzed data from HST/STIS (for the neutral gas content), VLT/UVES, Keck/HIRES or Magellan/MIKE (for the metallicity and dust content of H I gas), VLT/SINFONI (for SFR and kinematics of H II gas) and VLT/X-Shooter (for metallicity of H II gas). However, none of the data currently in hand can probe the faint optical continuum of these objects. Here we propose to observe these DLA/sub-DLA galaxies at z~1-2 using WFC3/UVIS and IR channels, to characterize the stellar content (extinction, stellar mass, age) and environment. The proposed observations will allow us to better probe the flow of gas around these galaxies, directly testing models of cold gas accretion from filaments and thus current theories of galaxy formation and evolution.

Peroux, Celine

2014-10-01

324

The Warm, Cold and Very Cold Dusty Universe  

E-print Network

We are living in a dusty universe: dust is ubiquitously seen in a wide variety of astrophysical environments, ranging from circumstellar envelopes around cool red giants to supernova ejecta, from diffuse and dense interstellar clouds and star-forming regions to debris disks around main-sequence stars, from comets to interplanetary space to distant galaxies and quasars. In this review I focus on interstellar grains, with particular emphasis on the extinction (absorption plus scattering) and emission properties of cold submicron-sized ``classical'' grains which, in thermal equilibrium with the ambient interstellar radiation field, obtain a steady-state temperature of \\~15--25K, warm nano-sized (or smaller) "ultrasmall" grains which are, upon absorption of an energetic photon, transiently heated to temperatures as high as a few hundred to over 1000K, and the possible existence of a population of very cold (< 10K) dust. Whether dust grains can really get down to "temperature" less than the 2.7K cosmic microwav...

Li, A

2005-01-01

325

Probing Cold Dense Nuclear Matter  

E-print Network

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, where a proton is knocked-out of the nucleus with high momentum transfer and high missing momentum, show that in 12C the neutron-proton pairs are nearly twenty times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

R. Subedi; R. Shneor; P. Monaghan; B. D. Anderson; K. Aniol; J. Annand; J. Arrington; H. Benaoum; F. Benmokhtar; W. Bertozzi; W. Boeglin; J. -P. Chen; Seonho Choi; E. Cisbani; B. Craver; S. Frullani; F. Garibaldi; S. Gilad; R. Gilman; O. Glamazdin; J. -O. Hansen; D. W. Higinbotham; T. Holmstrom; H. Ibrahim; R. Igarashi; C. W. de Jager; E. Jans; X. Jiang; L. Kaufman; A. Kelleher; A. Kolarkar; G. Kumbartzki; J. J. LeRose; R. Lindgren; N. Liyanage; D. J. Margaziotis; P. Markowitz; S. Marrone; M. Mazouz; D. Meekins; R. Michaels; B. Moffit; C. F. Perdrisat; E. Piasetzky; M. Potokar; V. Punjabi; Y. Qiang; J. Reinhold; G. Ron; G. Rosner; A. Saha; B. Sawatzky; A. Shahinyan; S. Širca; K. Slifer; P. Solvignon; V. Sulkosky; G. Urciuoli; E. Voutier; J. W. Watson; L. B. Weinstein; B. Wojtsekhowski; S. Wood; X. -C. Zheng; L. Zhu

2009-08-11

326

Probing Cold Dense Nuclear Matter  

E-print Network

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, where a proton is knocked-out of the nucleus with high momentum transfer and high missing momentum, show that in 12C the neutron-proton pairs are nearly twenty times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

Subedi, R; Monaghan, P; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Bertozzi, W; Boeglin, W; Chen, J -P; Choi, Seonho; Cisbani, E; Craver, B; Frullani, S; Garibaldi, F; Gilad, S; Gilman, R; Glamazdin, O; Hansen, J -O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; De Jager, C W; Jans, E; Jiang, X; Kaufman, L; Kelleher, A; Kolarkar, A; Kumbartzki, G; LeRose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Ron, G; Rosner, G; Saha, A; Sawatzky, B; Shahinyan, A; Širca, S; Slifer, K; Solvignon, P; Sulkosky, V; Urciuoli, G; Voutier, E; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Zheng, X -C; Zhu, L; 10.1126/science.1156675

2009-01-01

327

Probing Cold Dense Nuclear Matter  

SciTech Connect

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

Subedi, Ramesh; Shneor, R.; Monaghan, Peter; Anderson, Bryon; Aniol, Konrad; Annand, John; Arrington, John; Benaoum, Hachemi; Benmokhtar, Fatiha; Bertozzi, William; Boeglin, Werner; Chen, Jian-Ping; Choi, Seonho; Cisbani, Evaristo; Craver, Brandon; Frullani, Salvatore; Garibaldi, Franco; Gilad, Shalev; Gilman, Ronald; Glamazdin, Oleksandr; Hansen, Jens-Ole; Higinbotham, Douglas; Holmstrom, Timothy; Ibrahim, Hassan; Igarashi, Ryuichi; De Jager, Cornelis; Jans, Eddy; Jiang, Xiaodong; Kaufman, Lisa; Kelleher, Aidan; Kolarkar, Ameya; Kumbartzki, Gerfried; LeRose, John; Lindgren, Richard; Liyanage, Nilanga; Margaziotis, Demetrius; Markowitz, Pete; Marrone, Stefano; Mazouz, Malek; Meekins, David; Michaels, Robert; Moffit, Bryan; Perdrisat, Charles; Piasetzky, Eliazer; Potokar, Milan; Punjabi, Vina; Qiang, Yi; Reinhold, Joerg; Ron, Guy; Rosner, Guenther; Saha, Arunava; Sawatzky, Bradley; Shahinyan, Albert; Sirca, Simon; Slifer, Karl; Solvignon, Patricia; Sulkosky, Vince; Sulkosky, Vincent; Sulkosky, Vince; Sulkosky, Vincent; Urciuoli, Guido; Voutier, Eric; Watson, John; Weinstein, Lawrence; Wojtsekhowski, Bogdan; Wood, Stephen; Zheng, Xiaochao; Zhu, Lingyan

2008-06-01

328

Probing cold dense nuclear matter.  

SciTech Connect

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

Subedi, R.; Monaghan, P.; Shneor, R.; Anderson, B. D.; Aniol, K.; Arrington, J.; Physics; Kent State Univ.; Tel Aviv Univ.; California State Univ. Los Angeles

2008-06-13

329

Axinos as Cold Dark Matter  

SciTech Connect

The connection of Dark Matter (DM) to our particle physics model is still one of the open cosmological questions. In these proceedings I will argue that axinos can be successful Cold Dark Matter candidates in models with Supersymmetry and the Peccei-Quinn solution of the strong CP problem. If they are the Lightest Supersymmetric Particle (LSP), they can be produced in the right abundance by thermal scatterings and out of equilibrium decays of the Next-to-Lightest Supersymmetric Particles (NLSPs). Moreover if the NLSPs are charged, their decay could help us understand which is the LSP, e.g. between axino and gravitino.

Covi, Laura [DESY, Notkestrasse 85, D-22603 Hamburg (Germany)

2006-11-28

330

Cold cathode vacuum discharge tube  

DOEpatents

A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by chemical vapor deposition (CVD) or diamond-like carbon (DLC) deposition are disclosed. 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. 14 figs.

Boettcher, G.E.

1998-04-14

331

Cold cathode vacuum discharge tube  

DOEpatents

A cold cathode vacuum discharge tube, and method for making same, are disclosed 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. 15 figs.

Boettcher, G.E.

1998-03-10

332

Window performance in extreme cold  

NASA Astrophysics Data System (ADS)

Extreme cold causes heavy buildup of frost, ice and condensation on many windows. It also increases the incentive for improving the airtightness of windows against heat loss. Our study shows that tightening specifications for Alaskan windows to permit only 30% of the air leakage allowed by current American airtightness standards is economically attractive. We also recommend triple glazing in much of Alaska to avoid window icing in homes and barracks. We base our conclusions on a two year field study of Alaskan military bases that included recording humidity and temperature data, observing moisture accumulation on windows and measuring airtightness with a fan pressurized device.

Flanders, S. N.; Buska, J. S.; Barrett, S. A.

1982-12-01

333

Nonlinear dynamic modeling and resonance tuning of Galfenol vibration absorbers  

NASA Astrophysics Data System (ADS)

This paper investigates the semi-active control of a magnetically-tunable vibration absorber’s resonance frequency. The vibration absorber that is considered is a metal-matrix composite containing the magnetostrictive material Galfenol (FeGa). A single degree of freedom model for the nonlinear vibration of the absorber is presented. The model is valid under arbitrary stress and magnetic field, and incorporates the variation in Galfenol’s elastic modulus throughout the composite as well as Galfenol’s asymmetric tension-compression behavior. Two boundary conditions—cantilevered and clamped-clamped—are imposed on the composite. The frequency response of the absorber to harmonic base excitation is calculated as a function of the operating conditions to determine the composite’s capacity for resonance tuning. The results show that nearly uniform controllability of the vibration absorber’s resonance frequency is possible below a threshold of the input power amplitude using weak magnetic fields of 0-8 kA m-1. Parametric studies are presented to characterize the effect on resonance tunability of Galfenol volume fraction and Galfenol location within the composite. The applicability of the results to composites of varying geometry and containing different Galfenol materials is discussed.

Scheidler, Justin J.; Dapino, Marcelo J.

2013-08-01

334

Simulation, Fabrication and Characterization of THz Metamaterial Absorbers  

PubMed Central

Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical1 and experimental demonstration2 of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical3, near IR4, mid IR5 , THz6 , mm-wave7 , microwave8 and radio9 bands. Applications include perfect lenses10, sensors11, telecommunications12, invisibility cloaks13 and filters14,15. We have recently developed single band16, dual band17 and broadband18 THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers19. In our MM absorber the THz radiation is absorbed in a thickness of ~ ?/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems. PMID:23299442

Grant, James P.; McCrindle, Iain J.H.; Cumming, David R.S.

2012-01-01

335

Numerical Analysis of Ammonia-Water Bubble Absorber  

NASA Astrophysics Data System (ADS)

Thin film mode in ammonia-water absorption systems provides relatively high heat transfer coefficients and is stable during operation. However, thin film mode needs good liquid distributors. Bubble mode provides not only high heat transfer coefficients but also good mixing effect between the liquid and the vapor. The objective of this paper are to develop a design model for a bubble absorber with plate heat exchangers, to evaluate a simultaneous heat and mass transfer within both liquid and bubble and to clarify significant factors for a design of a ammonia-water bubble absorber. This analysis used experimental correlation from previous study of ammonia-water bubble absorption. It was clarified that heat transfer coefficient of wall in the absorber was a dominant factor in the heat transfer resistance of absorber, and a mass transfer enhancement depended on the inlet flow rate of vapor. The number of orifice in the absorber and inlet flow rate of liquid solution had influence on the height of absorber, but the orifice diameter had relatively a little influence. There were optimum conditions that the height of absorber reached at minimum, for the inlet flow rates of liquid solution

Hamamoto, Yoshimori; Nagano, Tatsuhiko; Yamada, Jun; Akisawa, Atsushi; Kashiwagi, Takao

336

Innovative Anti Crash Absorber for a Crashworthy Landing Gear  

NASA Astrophysics Data System (ADS)

This paper defines an innovative concept to anti-crash absorber in composite material to be integrated on the landing gear as an energy-absorbing device in crash conditions to absorb the impact energy. A composite cylinder tube in carbon fiber material is installed coaxially to the shock absorber cylinder and, in an emergency landing gear condition, collapses in order to enhance the energy absorption performance of the landing system. This mechanism has been developed as an alternative solution to a high-pressure chamber installed on the Agusta A129 CBT helicopter, which can be considered dangerous when the helicopter operates in hard and/or crash landing. The characteristics of the anti-crash device are presented and the structural layout of a crashworthy landing gear adopting the developed additional energy absorbing stage is outlined. Experimental and numerical results relevant to the material characterization and the force peaks evaluation of the system development are reported. The anti-crash prototype was designed, analysed, optimized, made and finally the potential performances of a landing gear with the additional anti-crash absorber system are tested by drop test and then correlated with a similar test without the anti-crash system, showing that appreciable energy absorbing capabilities and efficiencies can be obtained in crash conditions.

Guida, Michele; Marulo, Francesco; Montesarchio, Bruno; Bruno, Massimiliano

2014-06-01

337

Avionics Box Cold Plate Damage Prevention  

NASA Technical Reports Server (NTRS)

Over the years there have been several occurrences of damage to Space Shuttle Orbiter cold plates during removal and replacement of avionics boxes. Thus a process improvement team was put together to determine ways to prevent these kinds of damage. From this effort there were many solutions including, protective covers, training, and improved operations instructions. The focus of this paper is to explain the cold plate damage problem and the corrective actions for preventing future damage to aerospace avionics cold plate designs.

Stambolian, Damon; Larcher, Steven; Henderson, Gena; Tran, Donald

2011-01-01

338

The cold resistance of Macaronesian Sempervivoideae  

Microsoft Academic Search

Cold resistance of twenty-seven species of Macaronesian Sempervivoideae uniformly cultivated under cool moderate but not hardening conditions was measured. The resistance limits of all the tested species ranged between-4 and-10°C. Cold stress response was principially different: Cold resistance of about half of the tested species was due to freezing point lowering. This response type, avoidance of freezing, in which any

R. Lösch; L. Kappen

1981-01-01

339

Piezoelectric Actuators On A Cold Finger  

NASA Technical Reports Server (NTRS)

Developmental system for active suppression of vibrations of cold finger includes three piezoelectric actuators bonded to outer surface. Actuators used to suppress longitudinal and lateral vibrations of upper end of cold finger by applying opposing vibrations. Cold finger in question is part of a cryogenic system associated with an infrared imaging detector. When fully developed, system would be feedback sensor/control/actuator system automatically adapting to changing vibrational environment and suppresses pressure-induced vibrations by imposing compensatory vibrations via actuators.

Kuo, Chin-Po; Garba, John A.; Glaser, Robert J.

1995-01-01

340

International workshop on cold neutron sources  

Microsoft Academic Search

The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory on March 5 to 8, 1990. Cosponsored by Los Alamos and Oak Ridge National Laboratories, the meeting was organized as an International Workshop on Cold Neutron Sources and brought together experts in the field of cold-neutron-source design for reactors and spallation sources. Eighty-four people

G. J. Russell; C. D. West

1991-01-01

341

The FRM-II cold neutron source  

Microsoft Academic Search

The cold neutron source of new high flux research reactor FRM-II will be placed near the thermal flux maximum to obtain a cold neutron flux of 1×1014n\\/cm2\\/s and a thermal flux of 2.5×1014n\\/cm2\\/s in the moderator volume of 16l liquid deuterium at 25K. The total heat load in the cold part of the CNS generated by nuclear heating amounts to

Werner Gaubatz; Klaus Gobrecht

2000-01-01

342

International Workshop on Cold Neutron Sources  

Microsoft Academic Search

The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory (New Mexico, USA) from March 5–8, 1990. The meeting (cosponsored by Los Alamos and Oak Ridge National Laboratories) was organized as an International Workshop on Cold Neutron Sources, and brought together experts in the fields of reactor and spallation cold-neutron-source design. Eighty-four people from

Gary Russell; Colin West

1990-01-01

343

A search for HI 21cm absorption in strong MgII absorbers in the redshift desert  

NASA Astrophysics Data System (ADS)

We report results from a deep search for redshifted HI 21cm absorption in 55 strong MgII?2796 absorbers (having W?27960 > 0.5Å) at intermediate redshifts, 0.58 < zabs < 1.70, with the Green Bank Telescope (GBT) and the Giant Metrewave Radio Telescope (GMRT). Nine detections of HI 21cm absorption were obtained, all at 1.17 < zabs < 1.68, including three systems reported earlier by Gupta et al. (2007). Absorption was not detected at >3? significance in 32 other MgII absorbers, with 26 of these providing strong upper limits to the HI 21cm optical depth, ?3? < 0.013 per ~10kms-1. For the latter 26 systems, the spin temperature Ts of the absorber must be >[800 × f] K (where f is the covering factor), if the HI column density is >=2 × 1020cm-2, i.e. if the absorber is a damped Lyman ? system (DLA). Data on the remaining 13 systems of the sample were affected by radio frequency interference and were hence not useful. Two of the MgII absorbers, at zabs ~ 1.4106 towards 2003-025 and at zabs ~ 0.9115 towards 2149+212, are known DLAs. We detect HI 21cm absorption towards 2003-025 with the GMRT and estimate the spin temperature of the DLA to be Ts = [(905 +/- 380) × f] K. Conversely, the GBT observations of 2149+212 resulted in a non-detection of HI 21cm absorption, yielding the 3? limit Ts > [2700 × f] K. Excluding `associated' systems (within 3000kms-1 of the quasar redshift), the detection rate of HI 21cm absorption in strong MgII?2796 absorbers is per cent, at a 3? optical depth sensitivity of ~0.013 per 10kms-1. Comparing the detection rates of HI 21cm and damped Lyman ? absorption in strong MgII absorber samples yields a detection rate of HI 21cm absorption in DLAs of per cent, consistent with the detection rate in low-z DLAs. Since HI 21cm absorption arises in cold neutral gas, this indicates that most gas-rich galaxies contain significant fractions of cold HI by z ~ 1. Finally, we use the observed detection rate of HI 21cm absorption in MgII absorbers to infer the cosmological mass density of neutral gas in DLAs, assuming that (1) the average HI column density in our HI 21cm absorber sample is the same as that measured by Rao, Turnshek & Nestor in their DLA sample and (2) the detection rate of HI 21cm absorption in the DLAs of our MgII sample is the same as that in known DLAs at 0.09 < zabs < 3.45. We obtain ?GAS ~ (0.55+0.42-0.22) × 10-3, at , slightly lower than, but consistent with, the value obtained by Rao, Turnshek & Nestor from their DLA survey at similar redshifts.

Kanekar, N.; Prochaska, J. X.; Ellison, S. L.; Chengalur, J. N.

2009-06-01

344

Compression of a pyramidal absorber using multiple discrete coordinate transformation.  

PubMed

The discrete coordinate transformation (DCT), as a unique technique to control the electromagnetic waves, has been applied for creating all-dielectric devices recently. To extend the applicability of this technique, we propose the concept of multiple discrete coordinate transformation, which serves to deal with more complicated geometries in the transformation domain. As an example, an all-dielectric absorber is created by compressing a pyramidal absorber to a third of its original thickness using the multiple DCT technique. The Finite-Difference Time-Domain (FDTD) method based numerical simulations demonstrate the broadband performance of the transformation absorber from 2 GHz to 20 GHz. PMID:24787792

Tang, Wenxuan; Yang, Rui; Hao, Yang

2014-04-21

345

Fundamental research on oscillating water column wave power absorbers  

SciTech Connect

An oscillating water column (OWC) wave power absorber is one of the most promising devices, as well as the Salter Duck and the Clam. This paper presents a simple prediction method, in which the equivalent floating body approximation is used, for absorbing wave power characteristics of an oscillating water column device. The effects of the compressibility of air and inertia of an air turbine and electric generator on absorbed wave power are obtained by using the equivalent electric circuit concept. Both the experimental and theoretical studies are carried out in this paper.

Maeda, H.; Kato, W.; Kinoshita, T.; Masuda, K.

1985-03-01

346

Optimization of the acoustic absorption coefficients of certain functional absorbents  

NASA Technical Reports Server (NTRS)

The sound absorption coefficients of some functional absorbents (mineral wool plates) are determined by the reverberation chamber method. The influence of the angle of inclination of the sound absorbing material with respect to the surface to be treated is analyzed as well as the influence of the covering index, defined as the ratio of the designed area of a plate and the area of the treated surface belonging to another plate. As compared with the conventional method of applying sound-absorbing plates, the analyzed structures have a higher technological and economical efficiency. The optimum structure corresponds to an angle of inclination of 15 deg and a covering index of 0.8.

Pocsa, V.; Biborosch, L.; Veres, A.; Halpert, E.; Lorian, R.; Botos, T.

1974-01-01

347

Wedge absorber design and simulation for MICE Step IV  

SciTech Connect

In the Muon Ionization Cooling Experiment (MICE), muons are cooled by passing through material, then through RF cavities to compensate for the energy loss; which reduces the transverse emittance. It is planned to demonstrate longitudinal emittance reduction via emittance exchange in MICE by using a solid wedge absorber in Step IV. Based on the outcome of previous studies, the shape and material of the wedge were chosen. We address here further simulation efforts for the absorber of choice as well as engineering considerations in connection with the absorber support design.

Rogers, C.T.; /Rutherford; Snopok, P.; /IIT, Chicago /Fermilab; Coney, L.; Hanson, G.; /UC, Riverside

2011-03-01

348

Ultrabroadband absorber using a deep metallic grating with narrow slits  

NASA Astrophysics Data System (ADS)

We report an ultrabroadband absorber using a deep metallic grating with narrow slits in the infrared regime. In this absorber, the ultrabroadband electromagnetic wave has been perfectly transmitted through the vacuum-grating interface due to the plasmonic Brewster angle effect, and its energy can attenuate effectively through the slits because of the enhanced electric field inside the slits. In addition, simulation results show that this ultrabroadband absorber works over a narrow angle range which is a very important feature of directional thermal source.

Liao, Yan-Lin; Zhao, Yan

2015-01-01

349

Cold vacuum drying facility design requirements  

SciTech Connect

This document provides the detailed design requirements for the Spent Nuclear Fuel Project Cold Vacuum Drying Facility. Process, safety, and quality assurance requirements and interfaces are specified.

IRWIN, J.J.

1999-07-01

350

Evaporative cooling enhanced cold storage system  

DOEpatents

The invention provides an evaporatively enhanced cold storage system wherein a warm air stream is cooled and the cooled air stream is thereafter passed into contact with a cold storage unit. Moisture is added to the cooled air stream prior to or during contact of the cooled air stream with the cold storage unit to effect enhanced cooling of the cold storage unit due to evaporation of all or a portion of the added moisture. Preferably at least a portion of the added moisture comprises water condensed during the cooling of the warm air stream.

Carr, Peter (Cary, NC)

1991-01-01

351

Evaporative cooling enhanced cold storage system  

DOEpatents

The invention provides an evaporatively enhanced cold storage system wherein a warm air stream is cooled and the cooled air stream is thereafter passed into contact with a cold storage unit. Moisture is added to the cooled air stream prior to or during contact of the cooled air stream with the cold storage unit to effect enhanced cooling of the cold storage unit due to evaporation of all or a portion of the added moisture. Preferably at least a portion of the added moisture comprises water condensed during the cooling of the warm air stream. 3 figures.

Carr, P.

1991-10-15

352

Review on Cold-Formed Steel Connections  

PubMed Central

The concept of cold-formed light steel framing construction has been widespread after understanding its structural characteristics with massive research works over the years. Connection serves as one of the important elements for light steel framing in order to achieve its structural stability. Compared to hot-rolled steel sections, cold-formed steel connections perform dissimilarity due to the thin-walled behaviour. This paper aims to review current researches on cold-formed steel connections, particularly for screw connections, storage rack connections, welded connections, and bolted connections. The performance of these connections in the design of cold-formed steel structures is discussed. PMID:24688448

Tan, Cher Siang; Mohammad, Shahrin; Md Tahir, Mahmood; Shek, Poi Ngian

2014-01-01

353

Electrochemical generation of mercury cold vapor and its in-situ trapping in gold-covered graphite tube atomizers  

NASA Astrophysics Data System (ADS)

The combination of more efficient flow-through electrochemical mercury cold vapor generation with its in-situ trapping in a graphite tube atomizer is described. This coupled technique has been optimized to attain the maximum sensitivity for Hg determination and to minimize the limits of detection and determination. A laboratory constructed thin-layer flow-through cell with a platinum cathode served as the cold vapor generator. Various cathode arrangements with different active surface areas were tested. Automated sampling equipment for the graphite atomizer with an untreated fused silica capillary was used for the introduction of the mercury vapor. The inner surface of the graphite tube was covered with a gold foil placed against the sampling hole. The results attained for the electrochemical mercury cold vapor generation (an absolute limit of detection of 80 pg; peak absorbance, 3 ? criterion) were compared with the traditional vapor generation using NaBH 4 as the reducing agent (an absolute limit of detection of 124 pg; peak absorbance, 3 ? criterion). The repeatability at the 5 ng ml - 1 level was better than 4.1% (RSD) for electrochemical mercury vapor generation and better than 5.6% for the chemical cold vapor generation. The proposed method was applied to the determination the of Hg contents in a certified reference material and in spiked river water samples.

?ervený, Václav; Rychlovský, Petr; Netolická, Jarmila; Šíma, Jan

2007-03-01

354

Simulations of a cold-air pool associated with elevated wintertime ozone in the Uintah Basin, Utah  

NASA Astrophysics Data System (ADS)

Numerical simulations are used to investigate the meteorological characteristics of the 31 January-6 February 2013 cold-air pool in the Uintah Basin, Utah, and the resulting high ozone concentrations. Flow features affecting cold-air pools and air quality in the Uintah Basin are studied, including the following: penetration of clean air into the basin from across the surrounding mountains, elevated easterlies within the inversion layer, and thermally driven slope and valley flows. The sensitivity of the boundary layer structure to snow cover variations and cloud microphysics are also examined. Snow cover increases boundary layer stability by enhancing the surface albedo, reducing the absorbed solar insolation at the surface, and lowering near-surface air temperatures. Snow cover also increases ozone levels by enhancing solar radiation available for photochemical reactions. Ice-dominant clouds enhance cold-air pool strength compared to liquid-dominant clouds by increasing nocturnal cooling and decreasing longwave cloud forcing.

Neemann, E. M.; Crosman, E. T.; Horel, J. D.; Avey, L.

2015-01-01

355

Uptake of dissolved free amino acids by four cold-water coral species from the Mediterranean Sea  

NASA Astrophysics Data System (ADS)

Dissolved organic matter, which contains many compounds such as lipids, sugars and amino acids, is an important source of carbon and nitrogen for several symbiotic and asymbiotic tropical coral species. However, there is still no information on its possible uptake by cold-water coral species. In this study, we demonstrated that dissolved organic matter, in the form of dissolved free amino acids (DFAA), is actively absorbed by four cold-water coral species from the Mediterranean Sea. Although the uptake rates observed with 3 ?M DFAA concentration were one order of magnitude lower than those observed in tropical species, they corresponded to 12-50% of the daily excreted-nitrogen, and 16-89% of the daily respired-carbon of the cold-water corals. Consequently, DFAA, even at in situ concentrations lower than those tested in this study, can supply a significant amount of carbon and nitrogen to the corals, especially during periods when particulate food is scarce.

Gori, Andrea; Grover, Renaud; Orejas, Covadonga; Sikorski, Séverine; Ferrier-Pagès, Christine

2014-01-01

356

COLD-SHOCKINJURY AND RAPID COLD HARDENING IN THE FLESHFLY SARCOPHAGACRASSIPALPIS'  

E-print Network

COLD-SHOCKINJURY AND RAPID COLD HARDENING IN THE FLESHFLY SARCOPHAGACRASSIPALPIS' CHENG.PINGCHEN,2 inuoiuedirihl;;p";*. Tharborh nondiapause-anddiapause-programmedfliei respondto short-termchillingindicates that survivebriefperiodsoiioi-t.,np".u,ur.. INTRODUCTION Cold shockis a form of cellularinjury gbse.rve{immediatelyafter rapid

Lee Jr., Richard E.

357

WHAT IS A COLD? A "cold" is a syndrome of symptoms caused by  

E-print Network

numbers of ill students in close proximity to each other. Peak incidence of the common cold is in the late, these colors are commonly seen in the first 1-3 days. HOW IS A COLD DIAGNOSED? The diagnosis is made based system is your best ally against upper respiratory viruses. A common misconception is that colds last

Virginia Tech

358

A shallow-depth sloshing absorber for structural control  

NASA Astrophysics Data System (ADS)

Sloshing absorbers work on a similar principle to that of tuned vibration absorbers. A sloshing absorber consists of a tank, partially filled with liquid. The absorber is attached to the structure to be controlled, and relies on the structure's motion to excite the liquid. Consequently, a sloshing wave is produced at the liquid free surface possessing energy dissipative qualities. The primary objective of this paper is to demonstrate the effectiveness of employing liquid sloshing as a structural control mechanism. To this end, simple experimental observations are presented first. Then, numerical predictions obtained using smoothed particle hydrodynamics (SPH) are compared with experimental observations. The objective of this comparison is to demonstrate the modelling technique's ability to approximate the characteristics of such flows.

Marsh, A. P.; Prakash, M.; Semercigil, S. E.; Turan, Ö. F.

2010-07-01

359

Multiband plasmonic absorber based on transverse phase resonances  

E-print Network

We demonstrate a multiband plasmonic absorber based on transverse phase resonances. We show that the modification of conventional metallic surfaces of T-shape grooves can cause mode splitting of the plasmonic waveguide ...

Xu, Jun

360

Overcoming the far-field diffraction limit via absorbance modulation  

E-print Network

Diffraction limits the resolution of far-field lithography and imaging to about half of the wavelength, which greatly limits the capability of optical techniques. The proposed technique with absorbance modulation aims to ...

Tsai, Hsin-Yu Sidney

2011-01-01

361

Absorbing boundary conditions for second-order hyperbolic equations  

NASA Technical Reports Server (NTRS)

A uniform approach to construct absorbing artificial boundary conditions for second-order linear hyperbolic equations is proposed. The nonlocal boundary condition is given by a pseudodifferential operator that annihilates travelling waves. It is obtained through the dispersion relation of the differential equation by requiring that the initial-boundary value problem admits the wave solutions travelling in one direction only. Local approximation of this global boundary condition yields an nth-order differential operator. It is shown that the best approximations must be in the canonical forms which can be factorized into first-order operators. These boundary conditions are perfectly absorbing for wave packets propagating at certain group velocities. A hierarchy of absorbing boundary conditions is derived for transonic small perturbation equations of unsteady flows. These examples illustrate that the absorbing boundary conditions are easy to derive, and the effectiveness is demonstrated by the numerical experiments.

Jiang, Hong; Wong, Yau Shu

1990-01-01

362

Energy deposition studies for the LBNE beam absorber  

E-print Network

Results of detailed Monte Carlo energy deposition studies performed for the LBNE absorber core and the surrounding shielding with the MARS15 code are described. The model of the entire facility, that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system -- all with corresponding radiation shielding -- was developed using the recently implemented ROOT-based geometry option in the MARS15 code. This option provides substantial flexibility and automation when developing complex geometry models. Both normal operation and accidental conditions were studied. Various design options were considered, in particular the following: (i) filling the decay pipe with air or helium; (ii) the absorber mask material and shape; (iii) the beam spoiler material and size. Results of detailed thermal calculations with the ANSYS code helped to select the most viable absorber design options.

Rakhno, Igor L; Tropin, Igor S

2015-01-01

363

Radio-absorbing properties of nickel-containing schungite powder  

NASA Astrophysics Data System (ADS)

A nickel-containing shungite powder has been synthesized by means of chemical reduction from aqueous solutions. The chemical composition and radio-absorbing properties of this powder have been studied.

Lyn'kov, L. M.; Borbot'ko, T. V.; Krishtopova, E. A.

2009-05-01

364

Absorbing boundary conditions for second-order hyperbolic equations  

NASA Technical Reports Server (NTRS)

A uniform approach to construct absorbing artificial boundary conditions for second-order linear hyperbolic equations is proposed. The nonlocal boundary condition is given by a pseudodifferential operator that annihilates travelling waves. It is obtained through the dispersion relation of the differential equation by requiring that the initial-boundary value problem admits the wave solutions travelling in one direction only. Local approximation of this global boundary condition yields an nth-order differential operator. It is shown that the best approximations must be in the canonical forms which can be factorized into first-order operators. These boundary conditions are perfectly absorbing for wave packets propagating at certain group velocities. A hierarchy of absorbing boundary conditions is derived for transonic small perturbation equations of unsteady flows. These examples illustrate that the absorbing boundary conditions are easy to derive, and the effectiveness is demonstrated by the numerical experiments.

Jiang, Hong; Wong, Yau Shu

1989-01-01

365

21 CFR 878.4840 - Absorbable polydioxanone surgical suture.  

Code of Federal Regulations, 2013 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable polydioxanone...cardiovascular tissue where growth is expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and...

2013-04-01

366

21 CFR 878.4490 - Absorbable hemostatic agent and dressing.  

Code of Federal Regulations, 2013 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4490 Absorbable hemostatic agent and dressing. (a) Identification. An...

2013-04-01

367

21 CFR 878.4840 - Absorbable polydioxanone surgical suture.  

Code of Federal Regulations, 2012 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable polydioxanone...cardiovascular tissue where growth is expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and...

2012-04-01

368

21 CFR 878.4840 - Absorbable polydioxanone surgical suture.  

Code of Federal Regulations, 2014 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable polydioxanone...cardiovascular tissue where growth is expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and...

2014-04-01

369

21 CFR 878.4830 - Absorbable surgical gut suture.  

Code of Federal Regulations, 2011 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4830 Absorbable surgical gut suture. (a) Identification. An...

2011-04-01

370

21 CFR 878.4830 - Absorbable surgical gut suture.  

Code of Federal Regulations, 2012 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4830 Absorbable surgical gut suture. (a) Identification. An...

2012-04-01

371

21 CFR 878.4490 - Absorbable hemostatic agent and dressing.  

Code of Federal Regulations, 2010 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4490 Absorbable hemostatic agent and dressing. (a) Identification. An...

2010-04-01

372

21 CFR 878.4490 - Absorbable hemostatic agent and dressing.  

Code of Federal Regulations, 2014 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4490 Absorbable hemostatic agent and dressing. (a) Identification. An...

2014-04-01

373

21 CFR 878.4840 - Absorbable polydioxanone surgical suture.  

Code of Federal Regulations, 2011 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable polydioxanone...cardiovascular tissue where growth is expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and...

2011-04-01

374

21 CFR 878.4830 - Absorbable surgical gut suture.  

Code of Federal Regulations, 2010 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4830 Absorbable surgical gut suture. (a) Identification. An...

2010-04-01

375

21 CFR 878.4830 - Absorbable surgical gut suture.  

Code of Federal Regulations, 2014 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4830 Absorbable surgical gut suture. (a) Identification. An...

2014-04-01

376

21 CFR 878.4490 - Absorbable hemostatic agent and dressing.  

Code of Federal Regulations, 2012 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4490 Absorbable hemostatic agent and dressing. (a) Identification. An...

2012-04-01

377

21 CFR 878.4830 - Absorbable surgical gut suture.  

Code of Federal Regulations, 2013 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4830 Absorbable surgical gut suture. (a) Identification. An...

2013-04-01

378

21 CFR 878.4490 - Absorbable hemostatic agent and dressing.  

Code of Federal Regulations, 2011 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4490 Absorbable hemostatic agent and dressing. (a) Identification. An...

2011-04-01

379

Techniques for measuring intercepted and absorbed PAR in corn canopies  

NASA Technical Reports Server (NTRS)

The quantity of radiation potentially available for photosynthesis that is captured by the crop is best described as absorbed photosynthetically active radiation (PAR). Absorbed PAR (APAR) is the difference between descending and ascending fluxes. The four components of APAR were measured above and within two planting densities of corn (Zea mays L.) and several methods of measuring and estimating APAR were examined. A line quantum sensor that spatially averages the photosynthetic photon flux density provided a rapid and portable method of measuring APAR. PAR reflectance from the soil (Typic Argiaquoll) surface decreased from 10% to less than 1% of the incoming PAR as the canopy cover increased. PAR reflectance from the canopy decreased to less than 3% at maximum vegetative cover. Intercepted PAR (1 - transmitted PAR) generally overestimated absorbed PAR by less than 4% throughout most of the growing season. Thus intercepted PAR appears to be a reasonable estimate of absorbed PAR.

Gallo, K. P.; Daughtry, C. S. T.

1984-01-01

380

Liquid absorbent solutions for separating nitrogen from natural gas  

DOEpatents

Nitrogen-absorbing and -desorbing compositions, novel ligands and transition metal complexes, and methods of using the same, which are useful for the selective separation of nitrogen from other gases, especially natural gas.

Friesen, Dwayne T. (Bend, OR); Babcock, Walter C. (Bend, OR); Edlund, David J. (Redmond, OR); Lyon, David K. (Bend, OR); Miller, Warren K. (Bend, OR)

2000-01-01

381

Diffraction-Attenuation Resistant Beams in Absorbing Media  

E-print Network

In this work, in terms of suitable superpositions of equal-frequency Bessel beams, we develop a theoretical method to obtain nondiffractive beams in absorbing media (weakly conductive) capable to resist the loss effects for long distances.

Zamboni-Rached, M

2005-01-01

382

Absorbed dose measurements during routine equine radiographic procedures  

E-print Network

This study was performed in order to determine absorbed doses from scattered radiation to personnel during routine equine radiographic procedures and to determine if the protective apparel adequately reduced exposure from scattered radiation...

Salinas, Leticia Lamar

2012-06-07

383

Fluorescence spectroscopy: considerations for highly absorbing dissolved organic matter samples  

NASA Astrophysics Data System (ADS)

Fluorescence spectroscopy is a robust method for characterizing organic matter (OM). However, proper collection and correction of spectra are necessary to provide useful data. One important correction is the inner-filter correction, which primarily accounts for the inner-filter effect by adjusting for the wavelength dependent attenuation of emitted light by the solution prior to detection by the fluorometer. The most commonly used correction is based on an assumption that light is emitted at the center of the pathlength. Thus, the inner-filter effect is more pronounced in highly absorbing samples, and has the potential to skew the fluorescence spectra. For this study, the terrestrially derived Suwannee River fulvic acid (SRFA) and microbially derived Pony Lake fulvic acid (PLFA), from the International Humic Substances Society (IHSS), were diluted to incremental absorbances at a wavelength of 254 nm from 0.05 to 1.0 at pH 4 and 7. Three dimensional fluorescence spectra were measured and modeled with the Cory and McKnight (2005) parallel factor analysis (PARAFAC) model which resolves the fluorescence spectra into 13 components, including quinone-like and protein-like components. In the absence of inner-filter effects, plots of absorbance vs. loadings should be linear. Using the data from absorbance of 0.05 to 0.3, where the inner-filter affect is least pronounced, a linear regression was created and used as a baseline to predict component loadings at higher absorbance values in the absence of inner-filter effects. Results indicate that at absorbance values greater than 0.3, the commonly-used inner-filter correction is not able to remove the inner-filter effect. Therefore, in order to obtain reliable component loadings and correctly interpret the spectra, samples should be diluted to absorbance values less than 0.3 at 254 nm prior to collection of three dimensional fluorescence scans. The recommendation of a maximum absorbance of 0.3 agrees with the results of a study by Ohno (2002), which investigated several simpler fluorescence metrics. Suwannee River fulvic acid, pH 4, absorbance at 254nm vs. loading of component Q2. At the higher absorbances the component loadings are over-predicted compared to the linear regression, estimated from data with absorbance below 0.3, where the inner-filter effect is minimal.

Simone, B. E.; Miller, M.; McKnight, D. M.

2009-12-01

384

Analysis of a bubble absorber working with R22 and five organic absorbents  

NASA Astrophysics Data System (ADS)

A model of the absorption process in a vertical tubular bubble absorber working with R22-DMF, R22-DMA, R22-DMETEG, R22-DMEDEG and R22-NMP is developed using finite element method employing Galerkin's technique. The objective of this paper is to study the influence of the liquid and gas properties on the volumetric mass transfer coefficient. Analysis have also been done using ammonia-water as working fluid, the results obtained are compared with those in the literature and the agreement is found to be good. A correlation for mass transfer coefficient is proposed as a function of Reynolds number, Schmidt number and length to diameter ratio. The correlation can be used either in estimating the mass transfer rates or in fixing up any of the major design parameters namely length required for complete absorption and diameter. Zusammenfassung Mit Hilfe der Finitelement-Methode und des Galerkin-Verfahrens wird ein Modell des Absorptionsprozesses in einem vertikalen Blasensäulen-Absorber entwickelt, der mit den Fluiden R22-DMF, R22-DMA, R22-DMETEG, R22-DMEDEG und R22-NMP arbeitet. Ziel der Untersuchung ist die Ermittlung des Einflusses der Flüssigkeits- und Gaseigenschaften auf den volumetrischen Stoffübergangskoeffizienten. Untersuchungen mit Ammonikwasser als Arbeitsfluid ergaben gute Übereinstimmungen der Resultate mit solchen aus der Literatur. Eine Korrelationsgleichung für den Stoffaustauschkoeffizienten als Funktion der Reynolds-Zahl, der Schmidt-Zahl und des Länge/Durchmesserverhältnises wird vorgeschlagen. Hierraus lassen sich entweder die Stoffströme bestimmen oder bei Festlegung irgend eines Hauptparameters etwa die zur vollständigen Absorption erforderlichen Länge und der Durchmesser.

Sujatha, K. S.; Mani, A.; Murthy, S. Srinivasa

385

Light Absorbing Particle (LAP) Measurements in the Lower Stratosphere  

NASA Technical Reports Server (NTRS)

This viewgraph presentation covers the capabilities and design of the Single Particle Soot Photometer (SP-2), and reviews its role on the Sage III Ozone Loss Validation Experiment (SOLVE II) field campaign during 2003. On SOLVE II the SP-2 was carried into the Arctic onboard a DC-8 aircraft, in order to determine the size distribution of light-absorbing and non light-absorbing particles in the stratosphere. Graphs and tables relate some of the results from SOLVE II.

Baumgardner, D.; Raga, G. B.; Anderson, B.; Diskin, G.; Sachse, G.; Kok, G.

2003-01-01

386

A Search for Galaxies Producing Metal-rich Quasar Absorbers  

Microsoft Academic Search

Absorption lines in quasar spectra allow us to study intervening galaxies. Narrow-band imaging centered at redshifted H-alpha or [O II] emission at the absorber redshift, along with corresponding broad-band images, can be employed in order to isolate the absorbers from the quasar. Images obtained in narrowband and broadband filters using the NASA Goddard Fabry-Perot imager and Near-Infrared camera at Apache

Lorrie Straka; V. P. Kulkarni; D. G. York; M. R. Chun; M. Takamiya; B. E. Woodgate

2010-01-01

387

Star Library: Which Paper Towel is More Absorbent?  

NSDL National Science Digital Library

This group activity focuses on conducting an experiment to determine which of two brands of paper towels are more absorbent by measuring the amount of water absorbed. A two-sample t-test can be used to analyze the data, or simple graphics and descriptive statistics can be used as an exploratory analysis. Students are asked to think about design issues, and to write a short report stating their results and conclusions, along with an evaluation of the experimental design.

Bilder, Christopher R.; Boyer, John E.; Malone, Christopher; Rumsey, Deborah J.

2009-02-11

388

Optimization of X-ray absorbers for TES microcalorimeters  

Microsoft Academic Search

We have investigated the thermal, electrical, and structural properties of Bi and BiCu films that are being developed as X-ray absorbers for transition-edge sensor (TES) microcalorimeter arrays for imaging X-ray spectroscopy. Bi could be an ideal material for an X-ray absorber due to its high X-ray stopping power and low specific heat capacity, but it has a low thermal conductivity,

Naoko Iyomoto; John E. Sadleir; Enectali Figueroa-Feliciano; Tarek Saab; Simon R. Bandler; Caroline A. Kilbourne; James A. Chervenak; Dorothy Talley; Fred M. Finkbeiner; Regis P. Brekosky; Mark A. Lindeman; Richard L. Kelley; Frederick S. Porter; Kevin R. Boyce

2004-01-01

389

Impact-absorbing characteristics by applying ultrasonic vibration  

NASA Astrophysics Data System (ADS)

An impact-absorbing device that facilitates the application of ultrasonic vibrations was devised. Vibration distributions, springback characteristics, and impact-absorption characteristics were measured. We confirm that the springback amount decreases and the impact is absorbed upon the application of ultrasonic vibrations. When an aluminum alloy plate is crumpled, the maximum output voltage of the attached shock sensor decreases to 65% upon the application of ultrasonic vibrations as compared to when the ultrasonic vibrations are not applied.

Suzuki, Atsuyuki; Ueki, Eiichiro; Tsujino, Jiromaru

2012-05-01

390

Flue gas desulfurization with an electrostatic spraying absorber  

Microsoft Academic Search

A flue gas desulfurization device and process were developed and tested in this study. The process used an electrostatic spraying absorber (ESA) as the reactor, where SO was absorbed into an aqueous slurry of reactive Ca(OH). The absorption process was analyzed by using the two-film theory of mass-transfer. Both the liquid and gas side resistances were important, and the absorption

Binlin Dou; Young-Cheol Byun; Jungho Hwang

2008-01-01

391

Spectral estimators of absorbed photosynthetically active radiation in corn canopies  

NASA Technical Reports Server (NTRS)

Most models of crop growth and yield require an estimate of canopy leaf area index (LAI) or absorption of radiation. Relationships between photosynthetically active radiation (PAR) absorbed by corn canopies and the spectral reflectance of the canopies were investigated. Reflectance factor data were acquired with a Landsat MSS band radiometer. From planting to silking, the three spectrally predicted vegetation indices examined were associated with more than 95 percent of the variability in absorbed PAR. The relationships developed between absorbed PAR and the three indices were evaluated with reflectance factor data acquired from corn canopies planted in 1979 through 1982. Seasonal cumulations of measured LAI and each of the three indices were associated with greater than 50 percent of the variation in final grain yields from the test years. Seasonal cumulations of daily absorbed PAR were associated with up to 73 percent of the variation in final grain yields. Absorbed PAR, cumulated through the growing season, is a better indicator of yield than cumulated leaf area index. Absorbed PAR may be estimated reliably from spectral reflectance data of crop canopies.

Gallo, K. P.; Daughtry, C. S. T.; Bauer, M. E.

1985-01-01

392

Time-delayed absorber for controlling friction-driven vibration  

NASA Astrophysics Data System (ADS)

The efficacy of an active absorber based on the time-delayed displacement difference feedback in controlling friction-driven vibrations is discussed. Mainly two types of absorbers are considered: the tuned absorber having the natural frequency same as that of the primary system and the high-frequency absorber with the natural frequency higher than that of the primary system. The local stability analysis clearly demonstrates that the static equilibrium can be locally stabilized by appropriately selecting the control gain and the time-delay. The regions of stability are delineated in the plane of the control parameters. The robustness analysis is performed to help select the control parameters for the best performance. A method of optimizing the robustness of the system is presented. The influences of the absorber parameters on the degree of stability and the robustness are discussed. Numerical simulations of the system demonstrate that proper choices of the control parameters can also attain the global stability of the system. Numerical simulations reveal that apart from the globally stable static equilibrium or the coexisting locally stable static equilibrium with the stationary limit cycle vibrations, unbounded motions are also possible for some parameter values. Thus, care should be exercised in selecting the absorber parameters.

Chatterjee, S.; Mahata, P.

2009-04-01

393

Simulation of terahertz metamaterial absorbers with microbolometer structure  

NASA Astrophysics Data System (ADS)

The metamaterial absorber in terahertz (THz) region, with the metal pattern layer/dielectric spacer/metal reflective layer sandwich structure, is characterized in this paper. The principle of metamaterial absorber absorbing terahertz wave was introduced firstly. The top layer of metamaterial absorber is a periodically patterned with metallic subwavelength structure, which also serves as an electric resonator. The bottom layer is a thick metal plane, which is used to reduce THz wave transmittance. The dielectric layer between two metallic layers results in magnetic resonance and the resonance depends on the thickness and dielectric constant of the dielectric layer. The absorption of metamaterial absorber to terahertz wave was simulated with CST software. The relationship between the size of the metamaterial structure and absorption frequency was analyzed with the simulation results. The results indicate that the absorption frequency is affected by the cell constant and geometric structure of top metal pattern, and absorption rate is related to both the thickness of dielectric layer and the size of resonator. In the end, the possibility of integrating the metamaterial absorber with micro-bridge structure to design room temperature terahertz detector was discussed, and the manufacturing process was introduced about room temperature terahertz detector with high THz wave absorption rate.

Ding, Jie; Wang, Jun; Guo, Xiaopei; Jiang, Yadong; Fan, Lin

2014-09-01

394

Investigations on laser transmission welding of absorber-free thermoplastics  

NASA Astrophysics Data System (ADS)

Within the plastic industry laser transmission welding ranks among the most important joining techniques and opens up new application areas continuously. So far, a big disadvantage of the process was the fact that the joining partners need different optical properties. Since thermoplastics are transparent for the radiation of conventional beam sources (800- 1100 nm) the absorbance of one of the joining partners has to be enhanced by adding an infrared absorber (IR-absorber). Until recently, welding of absorber-free parts has not been possible. New diode lasers provide a broad variety of wavelengths which allows exploiting intrinsic absorption bands of thermoplastics. The use of a proper wavelength in combination with special optics enables laser welding of two optically identical polymer parts without absorbers which can be utilized in a large number of applications primarily in the medical and food industry, where the use of absorbers usually entails costly and time-consuming authorization processes. In this paper some aspects of the process are considered as the influence of the focal position, which is crucial when both joining partners have equal optical properties. After a theoretical consideration, an evaluation is carried out based on welding trials with polycarbonate (PC). Further aspects such as gap bridging capability and the influence of thickness of the upper joining partner are investigated as well.

Mamuschkin, Viktor; Olowinsky, Alexander; Britten, Simon W.; Engelmann, Christoph

2014-03-01

395

Newly developed broadband plasmonic absorber for uncooled infrared detectors  

NASA Astrophysics Data System (ADS)

In this paper, we introduce a floating plasmonic absorber having multiple resonances in the 8 ~ 14 ?m spectral range and broadband absorption characteristics by adjusting Drude relaxation rate of metal. This plasmonic broadband resonator capable of capturing light with a large optical cross-section area is able to substantially enhance the performance of micro-bolometer (response time, noise equivalent temperature difference, pixel size and so on) due to the significantly reduced thermal mass and conductance. Firstly, to adjust Drude relaxation rate, the mean crystalline size of metal was optimized by changing the deposition condition and the absorption characteristics of absorber were measured by Fourier transform infrared spectroscopy in the 8 ~ 14 ?m spectral range. The measurement results show that 1.62 times of broadening in bandwidth was obtained by decreasing the crystalline size from 5.73 nm to 3.18 nm while maintaining the maximum absorption at resonant wavelength of 10 ?m within 93 ~ 95%. Comparisons between measurements and CST microwave studio simulations show similar spectral absorption trends. And then, to integrate plasmonic absorber with micro-bolometer, various kinds of plasmonic absorbers which have combinations of short and long dipole resonators were designed and simulated. Based on these results, 12 ?m micro-bolometer pixels integrated with plasmonic broadband Ti absorber are designed and fabricated. The optimized Ti resonators with multiple resonance and small crystalline size absorb 88 % of the unpolarized radiation in the 8 ~ 14 ?m spectral range on the average.

Park, Hae-Seok; Nam, Sung Hyun; Hong, Hyun-Gue; Roh, Sookyoung; Yun, Seokho; Kim, JungWoo; Kwon, Dongil; Chung, U.-In

2014-03-01

396

Spectral estimators of absorbed photosynthetically active radiation in corn canopies  

NASA Technical Reports Server (NTRS)

Most models of crop growth and yield require an estimate of canopy leaf area index (LAI) or absorption of radiation. Relationships between photosynthetically active radiation (PAR) absorbed by corn canopies and the spectral reflectance of the canopies were investigated. Reflectance factor data were acquired with a LANDSAT MSS band radiometer. From planting to silking, the three spectrally predicted vegetation indices examined were associated with more than 95% of the variability in absorbed PAR. The relationships developed between absorbed PAR and the three indices were evaluated with reflectance factor data acquired from corn canopies planted in 1979 through 1982. Seasonal cumulations of measured LAI and each of the three indices were associated with greater than 50% of the variation in final grain yields from the test years. Seasonal cumulations of daily absorbed PAR were associated with up to 73% of the variation in final grain yields. Absorbed PAR, cumulated through the growing season, is a better indicator of yield than cumulated leaf area index. Absorbed PAR may be estimated reliably from spectral reflectance data of crop canopies.

Gallo, K. P.; Daughtry, C. S. T.; Bauer, M. E.

1984-01-01

397

Atomic Platters: Cold War Music  

NSDL National Science Digital Library

Along with ushering in a new age of global unrest and high anxiety, the emergence of the atomic bomb had a curious and not totally unpredictable effect on the world of popular (and not-so-popular) music. This site brings together these various subgenres of "atomic" music in a way that's rather fun, intriguing, and at times, a bit scary. Visitors can look through such subgenres as "Atomic", "Cold War", "Flying Saucer", and so on. While most of the songs are not available in their full form, visitors can read all of the lyrics and interpretive essays. Of course, visitors can find plenty of audio joy at the "CONELRAD Audio Archives" area. Herein are contained such gems as the positively odd "The Complacent Americans" and the equally lovable novelty album "The Goldwaters Sing Folk Songs to Bug the Liberals".

398

305 Building cold test facility management plan  

SciTech Connect

This document provides direction for the conduct of business in Building 305 for cold testing K-Basin tools and equipment. The Cold Test Facility represents a small portion of the overall building, and as such, the work instructions already implemented in the 305 Building will be utilized.

Feigenbutz, L.V.

1994-12-09

399

Electrodeposition process reduces cost of cold plates  

NASA Technical Reports Server (NTRS)

Efficient nickel heat-exchanger cold plates can be fabricated less expensively than stainless steel plates. If adapted to mass production, it is estimated that nickel cold plates might be made for about 30 percent less than stainless-steel plates.

Ruppe, E. P.

1980-01-01

400

Power, perceptions and the Cold War  

Microsoft Academic Search

Cold War Illusions: America, Europe and Soviet Power, 1969–1989 by Dana H. Allin. New York: St. Martin's Press, 1995. 267pp. $39.95.The Elusive Balance: Power and Perceptions During the Cold War by William Curti Wohlforth. Ithaca, NY: Cornell University Press, 1993. 317pp. £35.00 hbk, £15.00 pbk.

Gideon Rose

1996-01-01

401

A Cool Channel in Cold Transduction  

NSDL National Science Digital Library

Transient receptor potential melastatin 8 (TRPM8), a calcium-permeable cation channel activated by cold, cooling compounds and voltage, is the main molecular entity responsible for detection of cold temperatures in the somatosensory system. Here, we review the biophysical properties, physiological role, and near-membrane trafficking of this exciting polymodal ion channel.

PhD Ramon Latorre (Universidad de Chile Facultad de Ciencias Departamento de Biologý´a and Centro de Estudios Cientý´ficos)

2011-08-01

402

IEA HPP Annex 41 Cold Climate Heat  

E-print Network

#12;IEA HPP Annex 41 ­ Cold Climate Heat Pumps: Improving Low Ambient Temperature Performance of Air-Source Heat Pumps Van D. Baxter Oak Ridge National Laboratory European Heat Pump Summit Nuremberg ­ Cold Climate Heat Pumps Improving low ambient temperature performance of air-source heat pumps

Oak Ridge National Laboratory

403

Cold plasma processing technology makes advances  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cold plasma (AKA nonthermal plasma, cool plasma, gas plasma, etc.) is a rapidly maturing antimicrobial process being developed for applications in the food industry. A wide array of devices can be used to create cold plasma, but the defining characteristic is that they operate at or near room temper...

404

Cold pressure welded copper-constantan thermocouples  

Microsoft Academic Search

Cold pressure welding has been used to produce a lap junction between 0.15 mm thick strips of copper and constantan which had been plated with 2 mu m of nickel. The junction thickness after welding was 0.10 mm, and after further cold rolling to 0.06 mm a thermocouple performance within the requirements of BS 1041 (1966) was obtained.

R. Vipond

1975-01-01

405

The University of Texas Cold Neutron Source  

Microsoft Academic Search

A cold neutron source has been designed, constructed, and tested by the Nuclear Engineering Teaching Laboratory (NETL) at The University of Texas at Austin. The Texas Cold Neutron Source (TCNS) is located in one of the beam ports of the NETL 1-MW TRIGA Mark II research reactor. The main components of the TCNS are a cooled moderator, a heat pipe,

Kenan Ünlü; Carlos Ríos-Martínez; Bernard W. Wehring

1994-01-01

406

Cold fronts in cool core clusters  

E-print Network

Cold fronts have been detected both in merging and in cool core clusters, where little or no sign of a merging event is present. A systematic search of sharp surface brightness discontinuities performed on a sample of 62 galaxy clusters observed with XMM-Newton shows that cold fronts are a common feature in galaxy clusters. Indeed most (if not all) of the nearby clusters (z cold front. Understanding the origin and the nature of a such frequent phenomenon is clearly important. To gain insight on the nature of cold fronts in cool core clusters we have undertaken a systematic study of all contact discontinuities detected in our sample, measuring surface brightness, temperature and when possible abundance profiles across the fronts. We measure the Mach numbers for the cold fronts finding values which range from 0.2 to 0.9; we also detect a discontinuities in the metal profile of some clusters.

S. Ghizzardi; S. Molendi; M. Rossetti; A. Leccardi

2006-11-13

407

Colds and the flu - what to ask your doctor - child  

MedlinePLUS

... germs, called viruses, cause colds. Symptoms of the common cold include: Runny nose Nasal congestion Sneezing Sore throat ... 2011:chap 250. Turner RB, Hayden GF. The common cold. In: Kliegman RM, Behrman RE, Jenson HB, Stanton ...

408

Cold or Allergies: Which Is It? (For Parents)  

MedlinePLUS

... a lingering cold? - Michelle Seasonal allergies and the common cold can be so much alike that it's sometimes ... A to Z: Upper Respiratory Infection First Aid: Common Cold Why Is Hand Washing So Important? All About ...

409

Colds and the flu - what to ask your doctor - adult  

MedlinePLUS

... germs, called viruses, cause colds. Symptoms of the common cold include: Runny nose Nasal congestion Sneezing Sore throat ... Turner RB. The common cold. In: Goldman L, Schafer AI, eds. Cecil ... Philadelphia, PA: Saunders Elsevier; 2011:chap 369. Hayden FG. ...

410

ConcepTest: Hot/Cold Water Circulation  

NSDL National Science Digital Library

A fish tank is filled almost to the brim with room temperature water. Two containers of cold and hot water are prepared. Red coloring is added to the hot water, blue coloring is added to the cold water. The cold ...

411

7 CFR 305.16 - Cold treatment schedules.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Cold treatment schedules. 305.16 Section 305.16 Agriculture...SERVICE, DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS Cold Treatments § 305.16 Cold treatment schedules....

2010-01-01

412

Acoustic metamaterial structures based on multi-frequency vibration absorbers  

NASA Astrophysics Data System (ADS)

This paper presents a new metamaterial beam based on multi-frequency vibration absorbers for broadband vibration absorption. The proposed metamaterial beam consists of a uniform isotropic beam and small two-mass spring-mass- damper subsystems at many locations along the beam to act as multi-frequency vibration absorbers. For an infinite metamaterial beam, governing equations of a unit cell are derived using the extended Hamilton principle. The existence of two stopbands is demonstrated using a model based on averaging material properties over a cell length and a model based on finite element modeling and the Bloch-Floquet theory for periodic structures. For a finite metamaterial beam, because these two idealized models cannot be used for finite beams and/or elastic waves having short wavelengths, a finite-element method is used for detailed modeling and analysis. The concepts of negative effective mass and effective stiffness and how the spring-mass-damper subsystem creates two stopbands are explained in detail. Numerical simulations reveal that the actual working mechanism of the proposed metamaterial beam is based on the concept of conventional mechanical vibration absorbers. For an incoming wave with a frequency in one of the two stopbands, the absorbers are excited to vibrate in their optical modes to create shear forces to straighten the beam and stop the wave propagation. For an incoming wave with a frequency outside of but between the two stopbands, it can be efficiently damped out by the damper with the second mass of each absorber. Hence, the two stopbands are connected into a wide stopband. Numerical examples validate the concept and show that the structure's boundary conditions do not have significant influence on the absorption of high-frequency waves. However, for absorption of low-frequency waves, the structure's boundary conditions and resonance frequencies and the location and spatial distribution of absorbers need to be considered in design, and it is better to use heavier masses for absorbers.

Pai, P. Frank; Peng, Hao

2014-03-01

413

Analysis of Low z Absorbers in the QSO Spectra  

E-print Network

We present the results of reanalysis of low z Mg II absorption line sample compiled by SS92. The conditions on cloud parameters to produce N(Fe II)>N(Mg II) are obtained using photoionization models and curve of growth. Properties of Mg II absorbers with W(Fe II)/W(MgII) (definded as R) >and0.5 clouds W(Mg II) and dr are not correlated with z. However there is a clear anticorrelation between dr and W(Mg II). We find a clear decrease in the ratio of W(Fe II) and W(Mg II) with z. The N(z) as well as average N(Fe II) of Fe II lines selected absorbers are not evolving with z. The available data of LLS, are not showing any dependence of (tau_{LLS}) on z. We collected the LLS information for 53 QSO sight lines, for which details of Mg II absorption are available. There are 4 Mg II absorption systems which are not LLS at z which are lower than the mean z of the sample (z=1.1). In the higher z, where one expect to see 2.5\\pm1.4 such absorbers, we do not find any nonLLS Mg II absorbers. Individual systems with tau_{LLS}<3.0 are analysed. Our results imply some of the absorbers at z=0.6 have reached metallicity roughly around solar value. The required ionization parameters for these systems are less than 0.001 in most cases. Our results together with results obtained for high z absorbers confirm that mean ionization state of metal rich absorbing clouds falls with z.

R. Srianand

1995-11-18

414

Neutron-Absorbing Coatings for Safe Storage of Fissile Materials with Enhanced Shielding & Criticality Safety  

SciTech Connect

Neutron-absorbing Fe-based amorphous-metal coatings have been developed that are more corrosion resistant than other criticality-control materials, including Al-B{sub 4}C composites, borated stainless steels, and Ni-Cr-Mo-Gd alloys. The presence of relatively high concentration of boron in these coatings not only enhances its neutron-absorption capability, but also enables these coatings to exist in the amorphous state. Exceptional corrosion resistance has been achieved with these Fe-based amorphous-metal alloys through additions of chromium, molybdenum, and tungsten. The addition of rare earth elements such as yttrium has lowered the critical cooling rate of these materials, thereby rendering them more easily processed. Containers used for the storage of nuclear materials, and protected from corrosion through the application of amorphous metal coatings, would have greatly enhanced service lives, and would therefore provide greater long-term safety. Amorphous alloy powders have been successfully produced in multi-ton quantities with gas atomization, and applied to several half-scale spent fuel storage containers and criticality control structures with the high-velocity oxy-fuel (HVOF) thermal spray process. Salt fog testing and neutron radiography of these prototypes indicates that such an approach is viable for the production of large-scale industrial-scale facilities and containers. The use of these durable neutron-absorbing materials to coat stainless steel containers and storage racks, as well as vaults, hot-cell facilities and glove boxes could substantially reduce the risk of criticality in the event of an accident. These materials are particularly attractive for shielding applications since they are fire proof. Additionally, layers of other cold and thermal sprayed materials that include carbon and/or carbides can be used in conjunction with the high-boron amorphous metal coatings for the purpose of moderation. For example, various carbides, including boron, tungsten, and chromium carbide, as well as graphite particles can be co-deposited with a metallic binder phase with either thermal spray or cold spray technology. These moderator layers would also be fire resistant. By coating the vessels and piping used for spent fuel reprocessing, including slab and pencil tanks, enhanced criticality safety and substantially better corrosion resistance can be achieved simultaneously. Since these alloys are Fe-based, any substitution of these for high-performance Ni-based alloys is expected to result in a cost savings. Ultimately, the cost of these materials should comparable to that of stainless steels.

Choi, J; Farmer, J; Lee, C; Fischer, L; Boussoufi, M; Liu, B; Egbert, H

2007-07-03

415

Broadband infrared absorber based on plasmonic hybrid resonator  

NASA Astrophysics Data System (ADS)

Plasmonic resonances in metallic subwavelength structures have been widely exploited for a broad range of applications including nanoantennas, surface-enhanced Raman spectroscopy, chiral metamaterials, metamagnetism and absorbers. The phenomenon of extraordinary optical transmission (EOT) through subwavelength holes or slits based on the surface plasmon resonance is also extensively studied and has been applied for light harvesting. However, most of work about light harvesting devices suffer from many disadvantages such as narrow operating waveband, sensitive to the polarization state of the incident light, narrow accepting angles at a fixed azimuthal angle, which greatly limit their potential applications to spectroscopic detection and phase imaging. In this work, we present a broadband plasmonic resonant absorber in infrared regime. The plasmonic resonant absorber consists of a three-layer structure, i.e. two-dimensional metallic subwavelength hole arrays/dielectric-spacer/ thick metallic film from top to bottom. The designed plasmonic resonator is found to be polarization insensitive and omnidirectional due to the symmetry of the subwavelength hole array structure. The absorption efficiency of such absorber can be optimized by tuning the geometry of the metallic subwavelength structure and the thickness of the dielectric layer in between the two metallic films. The broadband efficient light absorbing property of the plasmonic resonant absorber can be explained by the synergetic effect of plasmonic resonance and Fabry-Perot (FP) resonance. It is shown that the periodic subwavelength metallic holes interact with the incident light to excite the surface plasmons so that the transmitted light intensity is significantly enhanced. The enhancement of the electric field near the metallic surface leads to an improved absorption. Moreover, FP cavity provides a resonant environment for the excited surface plasmons as well as the diffracted waves. As a result, the efficient light absorbing is achieved over a broad waveband. It should be noted that the proposed absorber can be applied to other working wavebands by carefully tuning the geometry of the metallic subwavelength structure and the thickness of the dielectric layer in between two metallic layers. The designed absorber may find important applications in solar cells, photodetectors, thermo-photovoltaic, and thermal emitters.

Liang, Qiuqun; Hao, Dongliang; Wang, Taisheng; Lu, Zhenwu; Sun, Qiang; Yu, Weixing

2013-08-01

416

Insulin secretion in sheep exposed to cold.  

PubMed Central

1. Cold exposure caused a marked decrease in insulin response to intravenous injection of glucose, with a sharply declining response over the first 4 days of cold exposure followed by a constant low response up to 13 days of the experimental cold period. 2. The glucose-induced insulin response was unaffected by concomitant infusion of phentolamine in the warm environment. In contrast, the low response of insulin secretion to glucose during cold exposure was so augmented by concomitant infusion of phentolamine as to exceed the response observed in the warm environment. 3. Intravenous infusion of phentolamine caused an increase in the concentration of plasma insulin in the cold but not in the warm environment. 4. Adrenaline completely abolished the insulin response to glucose in the warm environment. 5. Exposure to cold environment brought about an increase in urinary excretion of adrenaline and noradrenaline and in heart rate, but rectal temperature was unchanged. 6. It is concluded that cold exposure insufficient to cause hypothermia produces a marked decrease in insulin secretion by the pancreas of sheep, mediated through adrenergic alpha-receptors stimulated by augmented sympatho-adrenomedullary activity. PMID:7007619

Sasaki, Y; Takahashi, H

1980-01-01

417

Remote cooling circulator with cold valves  

NASA Astrophysics Data System (ADS)

A fluid loop can be effective for cooling some distance from a pulse tube cooler or in applications that require vibration isolation from the cooled object. Space pulse tube coolers are very efficient, but like all regenerative high frequency Stirling and pulse tube coolers, the cold head needs to be located near the compressor in order to minimize the input power to the cooler. To provide the directional gas flow from the oscillating flow pulse tube cooler we added cold reed valves to the pulse tube cold block of our flight proven high efficiency cooler (HEC) so that cold gas could be circulated without the need for an additional circulation pump and additional heat exchangers to cool the gas. In this test an improved smaller cold valve than that previously reported was installed and the remote cooling and the parasitic heat loads were measured. The measurements are compared to those of our previously reported cold valve tests as well as warm reed valve tests that used a second circulator compressor and recuperative heat exchanger. The large improvement in remote cooling power relative to the previous cold valve tests will be described.

Raab, Jeff; Maddocks, James R.; Nguyen, Tanh; Toma, Glen; Tward, Emmanuel

2012-06-01

418

Insight into the nonlinear absorbance of two related series of two-photon absorbing chromophores.  

PubMed

A comprehensive photophysical study of the linear and nonlinear absorption properties has been carried out on two series of two-photon absorbing dyes to gain insight into how structure-property relationships influence observed nonlinear absorption. The materials studied consist of an electron accepting benzothiazole group connected to an electron donating diphenylamine via a fluorene bridging group. Two series differ from each other by the addition of one phenyl group and for each series one-arm (dipolar, AF240 and AF270), two-arm (quadrupolar, AF287 and AF295), and three-arm (octupolar, AF350 and AF380) versions were studied. Overall the AF240 series exhibits higher intrinsic two-photon absorption (TPA) cross-sections than the AF270 series as well as enhanced nanosecond nonlinear absorption, with an increase with number of branches. The enhanced nanosecond nonlinearity is understood by taking into account the contribution from the singlet and triplet excited states and was verified by a two-photon assisted excited-state absorption model that satisfactorily predicts the nonlinear absorption of the chromophores. PMID:17388283

Rogers, Joy E; Slagle, Jonathan E; McLean, Daniel G; Sutherland, Richard L; Brant, Mark C; Heinrichs, James; Jakubiak, Rachel; Kannan, Ramamurthi; Tan, Loon-Seng; Fleitz, Paul A

2007-03-15

419

Systematic review of absorbable vs non-absorbable sutures used for the closure of surgical incisions  

PubMed Central

AIM: To report a systematic review of published randomized controlled trials (RCTs) investigating the role of absorbable suture (AS) against non-AS (NAS) used for the closure of surgical incisions. METHODS: RCTs investigating the use of AS vs NAS for the closure of surgical incisions were statistically analysed based upon the principles of meta-analysis and the summated outcomes were represented as OR. RESULTS: The systematic search of medical literature yielded 10 RCTs on 1354 patients. Prevalence of wound infection (OR = 0.97; 95%CI: 0.56, 1.69; Z = 0.11; P = 0.92) and operative morbidity (P = 0.45) was comparable in both groups. Nonetheless, the use of AS lead to lower risk of wound break-down (OR = 0.12; 95%CI: 0.04, 0.39; Z = 3.52; P < 0.0004). CONCLUSION: This meta-analysis of 10 RCTs demonstrates that the use of AS is similar to NAS for skin closure for surgical site infection and other operative morbidities. AS do not increase the risk of skin wound dehiscence, rather lead to a reduced risk of wound dehiscence compared to NAS. PMID:25548609

Sajid, Muhammad S; McFall, Malcolm R; Whitehouse, Pauline A; Sains, Parv S

2014-01-01

420

Warm Absorbers in the ROSAT Spectra of Quasars  

NASA Technical Reports Server (NTRS)

We present two ROSAT PSPC observations of the radio-loud, lobe-dominated quasar 3C 351, which shows an 'ionized absorber' in its X-ray spectrum. The factor 1.7 change in flux in the approx. 2 years between the observations allows a test of of models for this ionized absorber. The absorption feature at approx. 0.7 keV (quasar frame) is present in both spectra but with a lower optical depth when the source intensity - and hence the ionizing flux at the absorber - is higher, in accordance with a simple, single-zone, equilibrium photoionization model. Detailed modeling confirms this agreement quantitatively. The maximum response time of 2 years allows us to limit the gas density: n(sub e) greater than 2 x 10(exp 4)cm(exp -3); and the distance of the ionized gas from the central source R less than 19 pc. This produces a strong test for a photoionized absorber in 3C 351: a factor 2 flux change in approx. 1 week in this source must show non-equilibrium effects in the ionized absorber.

Fiore, Fabrizio

1998-01-01

421

Calorimetry at 10. 6. mu. m using organic volume absorbers  

SciTech Connect

Copper-Kapton laminate foils will be utilized as isoperibol calorimeters for pulsed energy measurements at Antares with apertures up to 1.5 m. These are volume absorbing calorimeters in which the radiation is absorbed in a layer tens of wavelengths thick, thereby reducing surface temperature and increasing damage threshold as compared to surface absorbing calorimeters. Kapton was chosen for its high absorption coefficient, 330 cm/sup -1/ at P(20) in the 10 ..mu..m band of CO/sub 2/, and its useful short pulse damage threshold, 2.8 J/cm/sup 2/. The copper backing integrates the absorbed heat pulse. The resultant temperature pulse is sensed by Type E thermocouples (chromel-constantan) soldered to the copper. Time vs voltage traces of the thermocouples can then be analyzed to obtain the energy absorbed. Calorimeters can be fabricated to virtually any size or shape, using photo-lithographic techniques. Utilizing single elements or several in a thermopile further expands the versatility of this technique.

Sollid, J.E.; Bjork, C.W.

1981-01-01

422

Role of absorbed solvent in polymer pen lithography.  

PubMed

We report on the dynamic role of solvents in molecular printing and show that material transport can be mediated by both environmental solvent (i.e., humidity) and solvent absorbed in the pen. To explore the transport of materials in the absence of environmental solvent, a hydrophobic polymer was patterned using a polydimethylsiloxane (PDMS) pen array that had been soaked in undecane, a nonpolar solvent that readily absorbs into PDMS. We also explored the patterning of the hydrophilic polymer polyethylene glycol (PEG) and found that, even though PDMS only absorbs trace amounts of water, soaking a PDMS pen array in water enables PEG deposition in completely dry environments for over 2 h. We find that the length of time one can pattern in a dry environment is determined by the availability of absorbed solvent, a relationship that we elucidate by comparing the performance of pens with varying ability to absorb water. Furthermore, a calculation accounting for the dynamics of retained water captures these effects completely, allowing for generalization of this result to other solvents and providing a way to tune the desired solvent retention profile. Taken together, this work explores the subtle and dynamic role of solvent on molecular printing and provides an alternative to strict environmental humidity control for reliable molecular printing. PMID:24320821

Eichelsdoerfer, Daniel J; Brown, Keith A; Wang, Mary X; Mirkin, Chad A

2013-12-19

423

Photodetector with absorbing region having resonant periodic absorption between reflectors  

DOEpatents

A photodetector is disclosed that is responsive to a wavelength or wavelengths of interest which have heretofore been unrealized. The photodetector includes a resonant cavity structure bounded by first and second reflectors, the resonant cavity structure being resonant at the wavelength or wavelengths of interest for containing a plurality of standing waves therein. The photodetector further includes a radiation absorbing region disposed within the resonant cavity structure, the radiation absorbing region including a plurality of radiation absorbing layers spaced apart from one another by a distance substantially equal to a distance between antinodes of adjacent ones of the standing waves. Each of radiation absorbing layers is spatially positioned at a location of one of the antinodes of one of the standing waves such that radiation absorption is enhanced. The radiation absorbing layers may be either bulk layers or quantum wells includes a plurality of layers, each of which is comprised of a strained layer of InGaAs. Individual ones of the InGaAs layers are spaced apart from one another by a GaAs barrier layer. 11 figs.

Bryan, R.P.; Olbright, G.R.; Brennan, T.M.; Tsao, J.Y.

1995-02-14

424

Photodetector with absorbing region having resonant periodic absorption between reflectors  

DOEpatents

A photodetector that is responsive to a wavelength or wavelengths of interest which have heretofore been unrealized. The photodetector includes a resonant cavity structure bounded by first and second reflectors, the resonant cavity structure being resonant at the wavelength or wavelengths of interest for containing a plurality of standing waves therein. The photodetector further includes a radiation absorbing region disposed within the resonant cavity structure, the radiation absorbing region including a plurality of radiation absorbing layers spaced apart from one another by a distance substantially equal to a distance between antinodes of adjacent ones of the standing waves. Each of radiation absorbing layers is spatially positioned at a location of one of the antinodes of one of the standing waves such that radiation absorption is enhanced. The radiation absorbing layers may be either bulk layers or quantum wells includes a plurality of layers, each of which is comprised of a strained layer of InGaAs. Individual ones of the InGaAs layers are spaced apart from one another by a GaAs barrier layer.

Bryan, Robert P. (Boulder, CO); Olbright, Gregory R. (Boulder, CO); Brennan, Thomas M. (Albuquerque, NM); Tsao, Jeffrey Y. (Albuquerque, NM)

1995-02-14

425

Absorbance enhancement in microplate wells for improved-sensitivity biosensors.  

PubMed

A generic optical biosensing strategy was developed that relies on the absorbance enhancement phenomenon occurring in a multiple scattering matrix. Experimentally, inserts made of glass fiber membrane were placed into microplate wells in order to significantly lengthen the trajectory of the incident light through the sample and therefore increase the corresponding absorbance. Enhancement factor was calculated by comparing the absorbance values measured for a given amount of dye with and without the absorbance-enhancing inserts in the wells. Moreover, the dilution of dye in solutions with different refractive indices (RI) clearly revealed that the enhancement factor increased with the ?RI between the membrane and the surrounding medium, reaching a maximum value (EF>25) when the membranes were dried. On this basis, two H2O2-biosensing systems were developed based on the biofunctionalization of the glass fiber inserts either with cytochrome c or horseradish peroxidase (HRP) and the analytical performances were systematically compared with the corresponding bioassay in solution. The efficiency of the absorbance-enhancement approach was particularly clear in the case of the cytochrome c-based biosensor with a sensitivity gain of 40 folds and wider dynamic range. Therefore, the developed strategy represents a promising way to convert standard colorimetric bioassays into optical biosensors with improved sensitivity. PMID:24491962

Suárez, Guillaume; Santschi, Christian; Plateel, Gregory; Martin, Olivier J F; Riediker, Michael

2014-06-15

426

Cold Flow Verification Test Facility  

SciTech Connect

The cold flow verification test facility consists of a 15-foot high, 3-foot diameter, domed vessel made of clear acrylic in two flanged sections. The unit can operate up to pressures of 14 psig. The internals include a 10-foot high jetting fluidized bed, a cylindrical baffle that hangs from the dome, and a rotating grate for control of continuous solids removal. The fluid bed is continuously fed solids (20 to 150 lb/hr) through a central nozzle made up of concentric pipes. It can either be configured as a half or full cylinder of various dimensions. The fluid bed has flow loops for separate air flow control for conveying solids (inner jet, 500 to 100000 scfh) , make-up into the jet (outer jet, 500 to 8000 scfh), spargers in the solids removal annulus (100 to 2000 scfh), and 6 air jets (20 to 200 scfh) on the sloping conical grid. Additional air (500 to 10000 scfh) can be added to the top of the dome and under the rotating grate. The outer vessel, the hanging cylindrical baffles or skirt, and the rotating grate can be used to study issues concerning moving bed reactors. There is ample allowance for access and instrumentation in the outer shell. Furthermore, this facility is available for future Cooperative Research and Development Program Manager Agreements (CRADA) to study issues and problems associated with fluid- and fixed-bed reactors. The design allows testing of different dimensions and geometries.

Shamsi, A.; Shadle, L.J.

1996-12-31

427

Cold Dust in Hot Regions  

NASA Astrophysics Data System (ADS)

We mapped five massive star-forming regions with the SCUBA-2 camera on the James Clerk Maxwell Telescope. Temperature and column density maps are obtained from the SCUBA-2 450 and 850 ?m images. Most of the dense clumps we find have central temperatures below 20 K, with some as cold as 8 K, suggesting that they have no internal heating due to the presence of embedded protostars. This is surprising, because at the high densities inferred from these images and at these low temperatures such clumps should be unstable, collapsing to form stars and generating internal heating. The column densities at the clump centers exceed 1023 cm-2, and the derived peak visual extinction values are from 25 to 500 mag for ? = 1.5-2.5, indicating highly opaque centers. The observed cloud gas masses range from ~10 to 103 M ?. The outer regions of the clumps follow an r -2.36 ± 0.35 density distribution, and this power-law structure is observed outside of typically 104 AU. All these findings suggest that these clumps are high-mass starless clumps and most likely contain high-mass starless cores.

Sreenilayam, Gopika; Fich, Michel; Ade, Peter; Bintley, Dan; Chapin, Ed; Chrysostomou, Antonio; Dunlop, James S.; Gibb, Andy; Greaves, Jane S.; Halpern, Mark; Holland, Wayne S.; Ivison, Rob; Jenness, Tim; Robson, Ian; Scott, Douglas

2014-03-01

428

Hot flakes in cold cases.  

PubMed

In the past, it was almost impossible for forensic scientists to separate DNA from an undefined number of different individuals in mixed stains where, for example, two or more suspects had handled the same weapon. Such samples often contain complex mixtures with the consequence of ambiguous or inconclusive mixed DNA profiles. Using the method described of comprehensive and/or targeted screening of shed cells adhering to tapings of garments or objects enables such stains to be individualized. To evaluate the method, 500 microscopically selected single skin flakes were analyzed using two different commercial STR kits to compare the success rates for each PCR typing system. The method has been validated for use in routine casework and has been shown to be rapid, sensitive, and reproducible. It can be predicted that many cases in the archives with body tapings, which have not yet been examined will benefit from this new or perhaps more appropriate, reanimated, technical development, and of particular importance are serious crimes, the so-called cold cases. The remarkable forensic value of this simple but time-consuming technique is exemplified by 2 out of approximately 100 cases already successfully solved using this approach. PMID:21258941

Schneider, Harald; Sommerer, Thomas; Rand, Steve; Wiegand, Peter

2011-07-01

429

Plasma Effects in Cold Atom Physics  

NASA Astrophysics Data System (ADS)

We discuss collective effects that can be relevant in cold atom physics. Similarities with plasma physics are emphasized. Both neutral and ionized atomic clouds are considered. We establish the basic frequencies and wave modes of a cloud of ultra-cold neutral atoms confined in a magneto-optical trap. The existence of a hybrid mode, Tonks-Dattner resonances and Mie oscillations are studied. Landau damping and resonant neutral atom-density wave interactions are also considered. Finally, free expansion and ambipolar diffusion regimes for a cold ionized cloud of atoms are discussed.

Mendonça, J. T.; Loureiro, J.; Terças, H.; Kaiser, R.

2008-03-01

430

The HI Environment of Nearby Lyman-alpha Absorbers  

NASA Technical Reports Server (NTRS)

We present the results of a VLA and WSRT search for H I emission from the vicinity of seven nearby clouds, which were observed in Ly-alpha absorption with HST toward Mrk 335, Mrk 501, and PKS 2155-304. Around the absorbers, we searched a volume of 4O' x 40' x 1000 km/s; for one of the absorbers we probed a velocity range of only 600 km/s. The H I mass sensitivity (5 sigma) very close to the lines of sight varies from 5 x 10(exp 6) solar mass at best to 5 x 10(exp 8) solar mass at worst. We detected H I emission in the vicinity of four out of seven absorbers. The closest galaxy we find to the absorbers is a small dwarf galaxy at a projected distance of 68 h(exp -1) kpc from the sight line toward Mrk 335. This optically uncataloged galaxy has the same velocity (V = 1970 km/s) as one of the absorbers, is fainter than the SMC, and has an H I mass of only 4 x 10(exp 7) solar mass. We found a somewhat more luminous galaxy at exactly the velocity (V = 5100 km/s) of one of the absorbers toward PKS 2155-304 at a projected distance of 230 h(exp -1) kpc from the sight line. Two other, stronger absorbers toward PKS 2155-304 at V approx. 17,000 km/s appear to be associated with a loose group of three bright spiral galaxies, at projected distances of 300 to 600 h(exp -1) kpc. These results support the conclusions emerging from optical searches that most nearby Ly-alpha forest clouds trace the large-scale structures outlined by the optically luminous galaxies, although this is still based on small-number statistics. We do not find any evidence from the H I distribution or kinematics that there is a physical association between an absorber and its closest galaxy. While the absorbing clouds are at the systemic velocity of the galaxies, the H I extent of the galaxies is fairly typical, and at least an order of magnitude smaller than the projected distance to the sight line at which the absorbers are seen. On the other hand, we also do not find evidence against such a connection. In total, we detected H I emission from five galaxies, of which two were previously uncataloged and one did not have a known redshift. No H I emission was detected from the vicinity of the two absorbers, which are located in a void and a region of very low galaxy density; but the limits are somewhat less stringent than for the other sight lines. These results are similar to what has been found in optically unbiased H I surveys. Thus, presence of Ly-alpha absorbers does not significantly alter the H I detection rate in their environment.

VanGorkom, J. H.; Carilli, C. L.; Stocke, John T.; Perlman, Eric S.; Shull, J. Michael

1996-01-01

431

Q-switched all-fiber lasers with saturable absorbers  

NASA Astrophysics Data System (ADS)

In this brief review we consider the relatively new design of the pulsed fiber lasers, namely lasers with the fiber saturable absorber (FSA). Main advantage of this design consists in a possibility to realize a simple all-fiber scheme of Q-switched laser. We show that such lasers can be based on the different types of the fiber absorber and operate in the different spectral ranges. Up to now a set of the pulsed lasers were build. Pulse energy from several ?J to several hundred ?J was demonstrated. Pear power was changed from tens W to several kW with the pulse duration from 50 ns to 1 ?s. We show that described principles of Q-switching can be applied for other types of the fiber lasers. Also, new fiber absorbers are suggested.

Kurkov, A. S.

2011-05-01

432

System size expansion for systems with an absorbing state.  

PubMed

The well-known van Kampen system size expansion, while of rather general applicability, is shown to fail to reproduce some qualitative features of the time evolution for systems with an absorbing state, apart from a transient initial time interval. We generalize the van Kampen ansatz by introducing a new prescription leading to non-Gaussian fluctuations around the absorbing state. The two expansion predictions are explicitly compared for the infinite range voter model with speciation as a paradigmatic model with an absorbing state. The new expansion, both for a finite size system in the large time limit and at finite time in the large size limit, converges to the exact solution as obtained in a numerical implementation using the Gillespie algorithm. Furthermore, the predicted lifetime distribution is shown to have the correct asymptotic behavior. PMID:21405654

Di Patti, Francesca; Azaele, Sandro; Banavar, Jayanth R; Maritan, Amos

2011-01-01

433

The precipitation synthesis of broad-spectrum UV absorber nanoceria  

SciTech Connect

In this paper the possibility of nanoceria as broad-spectrum UV absorber was evaluated. Nanoceria were synthesized by precipitation process from cerium nitrate solution and ammonium hydroxide as precipitant agent. Isopropanol was mixed with water as solvent to prevent hard agglomeration. The structure of resulting nanoceria was characterized by x-ray diffractometer (XRD). The transparency in the visible light and efficiency of protection in UV A region were studied using ultraviolet-visible (UV - Vis) spectrophotometer. The results show that nanoceria possess good tranparency in visible light and high UV light absorption. The critical absorption wavelenght of 368 nm was obtained which is desirable for excellent broad-spectrum protection absorbers. Moreover, analysis of photodegradation nanoceria to methylene blue solution shows poor photocatalytic activity. It indicates that nanoceria suitable for used as UV absorber in personal care products.

Nurhasanah, Iis; Sutanto, Heri; Puspaningrum, Nurul Wahyu [Department of Physics, Faculty of Science and Mathematics, Universitas Diponegoro Jl. Prof. Soedarto, S.H, Tembalang Semarang 50275 (Indonesia)] [Department of Physics, Faculty of Science and Mathematics, Universitas Diponegoro Jl. Prof. Soedarto, S.H, Tembalang Semarang 50275 (Indonesia)

2013-09-09

434

The Absorbing Properties of Two-Dimensional Plasma Photonic Crystals  

NASA Astrophysics Data System (ADS)

Plasma photonic crystals composed of periodic plasma and dielectric materials have attracted considerable attention because of their tunable photonic band gaps, but only their band structures or negative refractive index properties have been addressed in previous works. In this paper, through studying the transmission and reflection characteristics of two types of two-dimensional plasma photonic crystals, it is found that plasma photonic crystals play an important role in absorbing waves, and they show broader band and higher amplitude absorption characteristics than bulk plasmas. Also, the absorption of plasma photonic crystals can be tuned via plasma parameters; varying the collision frequency can make the bandwidth and amplitude tunable, but cannot change the central frequency, whereas varying the plasma frequency would control both the location and the amplitude of the absorbers. These features of plasma photonic crystals have potential for terahertz tunable absorber applications.

Qi, Limei; Li, Chao; Fang, Guangyou; Gao, Xiang

2015-01-01

435

Integration of regenerative shock absorber into vehicle electric system  

NASA Astrophysics Data System (ADS)

Regenerative/Energy harvesting shock absorbers have a great potential to increase fuel efficiency and provide suspension damping simultaneously. In recent years there's intensive work on this topic, but most researches focus on electricity extraction from vibration and harvesting efficiency improvement. The integration of electricity generated from regenerative shock absorbers into vehicle electric system, which is very important to realize the fuel efficiency benefit, has not been investigated. This paper is to study and demonstrate the integration of regenerative shock absorber with vehicle alternator, battery and in-vehicle electrical load together. In the presented system, the shock absorber is excited by a shaker and it converts kinetic energy into electricity. The harvested electricity flows into a DC/DC converter which realizes two functions: controlling the shock absorber's damping and regulating the output voltage. The damping is tuned by controlling shock absorber's output current, which is also the input current of DC/DC converter. By adjusting the duty cycles of switches in the converter, its input impedance together with input current can be adjusted according to dynamic damping requirements. An automotive lead-acid battery is charged by the DC/DC converter's output. To simulate the working condition of combustion engine, an AC motor is used to drive a truck alternator, which also charges the battery. Power resistors are used as battery's electrical load to simulate in-vehicle electrical devices. Experimental results show that the proposed integration strategy can effectively utilize the harvested electricity and power consumption of the AC motor is decreased accordingly. This proves the combustion engine's load reduction and fuel efficiency improvement.

Zhang, Chongxiao; Li, Peng; Xing, Shaoxu; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

2014-03-01

436

Shift of Optical Absorbance with Pressure in Star Polymers  

NASA Astrophysics Data System (ADS)

The optical absorbance dependence on pressure is studied for star polymers dispersed (less than 1% wt./wt.) in either polymethylmethacrylate or polycarbonate. The star polymer is composed of a hyperbranched core and ?-conjugated polymer arms. The optical absorbance red shifts with increasing pressure and is expected to be due to increase in the conjugation length. The sensitivity on pressure is greater with the star polymers than for a pure linear polymer of the conjugated arm. The proposed enhancement mechanism is a non-uniform distribution of strain in analogy with the impact toughening of a matrix material by multidimensional additives.

Ferguson, John; Long, Barry

2006-03-01

437

Vibration analysis of rotor blades with pendulum absorbers  

NASA Technical Reports Server (NTRS)

A comprehensive vibration analysis of rotor blades with spherical pendulum absorbers is presented. Linearized equations of motion for small oscillations about the steady-state deflection of a spherical pendulum on elastic rotor blades undergoing coupled flapwise bending, chordwise bending, and torsional vibrations are obtained. A transmission matrix formulation is given to determine the natural vibrational characteristics of rotor blades with spherical or simple flapping pendulum absorbers. The natural frequencies and mode shapes of a hingeless rotor blade with a spherical pendulum are computed.

Murthy, V. R.; Hammond, C. E.

1979-01-01

438

Parallel-Plate Acoustic Absorbers For Hot Environments  

NASA Technical Reports Server (NTRS)

Stacking patterns and materials chosen to suppress noise. Acoustic liners incorporating parallel-plate absorbing elements proposed for use in suppressing broadband aerodynamic noise originating in flows of hot gases in ducts. One potential application lies in suppressing noise generated in exhaust-jet mixer/ejectors in propulsion system of proposed High-Speed Civil Transport. In addition, such absorbers useful in any situation in which high temperature limits use of such conventional resonant acoustic-liner materials as perforated face sheets bonded to honey-comb-core panels.

Doychak, Joseph; Parrot, Tony L.

1995-01-01

439

Croconic acid - An absorber in the Venus clouds?  

NASA Technical Reports Server (NTRS)

The absorbing species responsible for the UV cloud features and pale yellow hue of the Venus clouds is presently suggested to be the carbon monoxide-polymer croconic acid, which strongly absorbs in the blue and near-UV. Laboratory absorption-coefficient measurements of a dilute solution of croconic acid in sulfuric acid are used as the bases of cloud-scattering models; the Venus planetary albedo's observed behavior in the blue and near-UV are noted to be qualitatively reproduced. Attention is given to a plausible croconic acid-production mechanism for the Venus cloudtop region.

Hartley, Karen K.; Wolff, Andrew R.; Travis, Larry D.

1989-01-01

440

Electromagnetic propagation in PEC and absorbing curved S-ducts  

NASA Technical Reports Server (NTRS)

A finite-element Galerkin formulation has been developed to study transverse magnetic (TM) wave propagation in 2-D S-curved ducts with both perfectly conducting and absorbing walls. The reflection and transmission at the entrances and the exits of the curved ducts are determined by coupling the finite-element solutions in the curved ducts to the eigenfunctions of an infinite, uniform, perfectly conducting duct. Example solutions are presented for a double mitred and S-ducts of various lengths. The length of the S-duct is found to significantly effect the reflective characteristics of the duct. Also, the effect of curvature on an absorbing duct is illustrated.

Baumeister, Kenneth J.

1988-01-01

441

Small-size metamaterial perfect absorber operating at low frequency  

NASA Astrophysics Data System (ADS)

A small-size metamaterial perfect absorber operating at low frequency is proposed. Due to the special design, the unit-cell dimension with respect to wavelength is very small, a/? ? 1/17, at the absorption frequency of 377 MHz. The absorption frequency is strongly dependent on the length of zigzag wire. In addition, the absorption is more than 94% in a wide range of incident angle of electromagnetic wave up to 50°. The results show that the proposed absorber is promising to be applied into devices in radio region.

Bui, Son Tung; Khuyen Bui, Van; Dung Nguyen, Van; Yoo, YoungJoon; Kim, Ki Won; Vu, Dinh Lam; Lee, YoungPak

2014-12-01

442

Dendritic wideband metamaterial absorber based on resistance film  

NASA Astrophysics Data System (ADS)

A type of dendritic wideband metamaterial absorber was designed and constructed from resistance film composed of indium-tin oxide conductive film having a dendritic metamaterial structure, dielectric layer made of polymethacrylimide foam, and metallic sheet based on the equivalent circuit model. In terms of normal incidence, the simulation using the absorber yielded operating absorption rates >80 % in the frequency range of 8-27.9 GHz. In addition, the experimental measurements verified 8-17 GHz range of more than 80 % absorption rate, whereas its relative bandwidth reached 72 %. Moreover, this reasonable absorption performance was maintained for oblique incidences of <60°. The effects of dielectric layer thickness on absorption properties were verified.

Wang, Bing; Gong, Bo Yi; Wang, Mei; Weng, Bin; Zhao, Xiaopeng

2014-12-01

443

An extremely broad band metamaterial absorber based on destructive interference.  

PubMed

We propose a design of an extremely broad frequency band absorber based on destructive interference mechanism. Metamaterial of multilayered SRRs structure is used to realize a desirable refractive index dispersion spectrum, which can induce a successive anti-reflection in a wide frequency range. The corresponding high absorptance originates from the destructive interference of two reflection waves from the two surfaces of the metamaterial. A strongly absorptive bandwidth of almost 60 GHz is demonstrated in the range of 0 to 70 GHz numerically. This design provides an effective and feasible way to construct broad band absorber in stealth technology, as well as the enhanced transmittance devices. PMID:22108966

Sun, Jingbo; Liu, Lingyun; Dong, Guoyan; Zhou, Ji

2011-10-24

444

High-Efficiency Absorber for Damping the Transverse Wake Fields  

SciTech Connect

Transverse wake fields generated by intense beams may propagate long distances in the vacuum chamber and dissipate power in different shielded elements such as bellows, vacuum valves or vacuum pumps. Induced heating in these elements may be high enough to deteriorate vacuum conditions. We have developed a broadband water-cooled bellows-absorber to capture and damp these harmful transverse fields without impacting the longitudinal beam impedance. Experimental results at the PEP-II SLAC B-factory demonstrate high efficiency of this device. This absorber may be useful in other machines like synchrotron light sources or International Linear Collider.

Novokhatski, A.; Seeman, J.; Weathersby, S.; /SLAC

2007-02-28

445

Study of temperature distribution of a pyramidal EM-wave absorber under high power injection  

Microsoft Academic Search

Utilization of electromagnetic absorbers under high power is increasing. The absorbers are used in anechoic chambers for estimation of performance of high power radars. Variation of the absorption characteristics of the absorbers under such condition is expected, due to the generation of heat or temperature change. In this paper, first temperature distribution of a pyramidal EM-wave absorber under high power

Shinya Watanabe; Tetsuhiro Sasagawa; Osamu Hashimoto; Toshifumi Saito

2007-01-01

446

DEVELOPMENT AND CAPABILITIES OF SPECIAL ABSORBERS FOR HIGH-POWER APPLICATIONS  

Microsoft Academic Search

This paper describes the power handling tests on a selection of Emerson & Cumings Microwave Products pyramidal high power absorbers. Especially the latest developed high power absorber ECCOSORB HFX-HC is discussed. The hollow concept of this absorber as well as the open-cell structure and high temperature resistance of the absorber panels result in an optimal power handling capability. Steady state

Nancy Laeveren; Jan Dauwen; Peter Van Roy

447

Cold vacuum drying facility design requirements  

SciTech Connect

This release of the Design Requirements Document is a complete restructuring and rewrite to the document previously prepared and released for project W-441 to record the design basis for the design of the Cold Vacuum Drying Facility.

Irwin, J.J.

1997-09-24

448

Animal Adaptation and Acclimatization to Cold  

ERIC Educational Resources Information Center

This article examines the mechanisms of adaptation and acclimatization of animals to cold temperatures. The differences between the two processes are explained and terms are defined. Graphs and drawings illustrate the article. (MA)

Phillips, R. E.; Watson, C. A.

1977-01-01

449

STS.436 Cold War Science, Spring 2004  

E-print Network

This course examines the history and legacy of the Cold War on science, looking predominantly at examples in the United States. It begins by exploring scientists’ new political roles after World War II, ranging from elite ...

Kaiser, David

450

Catching a Cold When It's Warm  

MedlinePLUS

... colds, you’re probably talking about a non-polio enterovirus infection.” Enteroviruses can infect the tissues in ... system and elsewhere. A few enteroviruses can cause polio, but vaccines have mostly eliminated these viruses from ...

451

Metal Enrichment Discriminators of Cold Fronts  

E-print Network

Cold fronts are sharp surface brightness discontinuities characterized by a jump in gas temperature accompanied by a decline in X-ray surface brightness such that the gas pressure remains continuous across the front and, thus, these structures differ from bow shocks. Models suggest that cold fronts can be generated by external mechanisms involving the accretion of a subsystem with a remnant "cold core". However, internal mechanisms can also create cold fronts, such as gravitational scattering of subclumps or cD oscillation around the bottom of the potential well. These competing models for their formation can be discriminated through the measurements of the SN Type contamination across the front, which in turn can be determined from metal abundance ratios as measured from an ensemble of elements. Here we present the preliminary results of such analysis using a sample of clusters observed with Chandra.

Renato Dupke

2005-11-18

452

Metal Enrichment Discriminators of Cold Fronts  

E-print Network

Cold fronts are sharp surface brightness discontinuities characterized by a jump in gas temperature accompanied by a decline in X-ray surface brightness such that the gas pressure remains continuous across the front and, thus, these structures differ from bow shocks. Models suggest that cold fronts can be generated by external mechanisms involving the accretion of a subsystem with a remnant "cold core". However, internal mechanisms can also create cold fronts, such as gravitational scattering of subclumps or cD oscillation around the bottom of the potential well. These competing models for their formation can be discriminated through the measurements of the SN Type contamination across the front, which in turn can be determined from metal abundance ratios as measured from an ensemble of elements. Here we present the preliminary results of such analysis using a sample of clusters observed with Chandra.

Dupke, R

2005-01-01

453

Cold quark matter in compact stars  

SciTech Connect

We used an equation of state for the cold quark matter to the study of properties of quark stars. We also discuss the absolute stability of quark matter and compute the mass-radius relation for self-bound stars.

Franzon, B.; Fogaca, D. A.; Navarra, F. S. [Instituto de Fisica, Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-090 Sao Paulo, SP (Brazil); Horvath, J. E. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao, 1226, 05508-090, Sao Paulo, SP (Brazil)

2013-03-25

454

Cold-induced changes in amphibian oocytes  

SciTech Connect

Female Pleurodeles waltl newts (Amphibia, urodele), usually raised at 20 degrees C, were submitted to low temperatures; oocytes responded to this cold stress by drastic changes both in lampbrush chromosome structure and in protein pattern. Preexisting lateral loops of lampbrush chromosomes were reduced in size and number, while cold-induced loops which were tremendously developed, occurred on defined bivalents of the oocyte at constant, reproducible sites. A comparison of protein patterns in control and stressed oocytes showed two main differences: in stressed oocytes, overall protein synthesis was reduced, except for a set of polypeptides, the cold-stress proteins; second, there was a striking inversion of the relative amount of beta- and gamma-actin found in the oocyte nucleus before and after cold stress. Whereas beta-actin was the predominant form in control oocytes, gamma-actin became the major form in stressed oocytes.

Angelier, N.; Moreau, N.A.; N'Da, E.A.; Lautredou, N.F. (Centre de Biologie Cellulaire, Ivry-sur-Seine (France))

1989-08-01

455

Herpes Simplex (Cold Sores and Genital Herpes)  

MedlinePLUS

... 19, 2014 Select a Language: Fact Sheet 508 Herpes Simplex (Cold Sores and Genital Herpes) WHAT IS HERPES? HSV AND HIV HOW IS HSV TRANSMITTED? HOW IS HERPES TREATED? CAN HERPES BE PREVENTED? THE BOTTOM LINE ...

456

Diffraction-contrast imaging of cold atoms .  

E-print Network

??We consider the inverse problem of in-line holography, applied to minimally-destructive imagingof cold atom clouds. Absorption imaging near resonance provides a simple, but destructive measurementof… (more)

Turner, Lincoln D.

2005-01-01

457

Wire and Cable Cold Bending Test  

NASA Technical Reports Server (NTRS)

One of the factors in assessing the applicability of wire or cable on the lunar surface is its flexibility under extreme cold conditions. Existing wire specifications did not address their mechanical behavior under cold, cryogenic temperature conditions. Therefore tests were performed to provide this information. To assess this characteristic 35 different insulated wire and cable pieces were cold soaked in liquid nitrogen. The segments were then subjected to bending and the force was recorded. Any failure of the insulation or jacketing was also documented for each sample tested. The bending force tests were performed at room temperature to provide a comparison to the change in force needed to bend the samples due to the low temperature conditions. The results from the bending tests were plotted and showed how various types of insulated wire and cable responded to bending under cold conditions. These results were then used to estimate the torque needed to unroll the wire under these low temperature conditions.

Colozza, Anthony

2010-01-01

458

Cold spray deposition of nanocrystalline aluminum alloys  

NASA Astrophysics Data System (ADS)

Aluminum 5083 powder was mechanically milled under liquid nitrogen to achieve a nanocrystalline grain size in the range of 20 to 30 nm. The powder was subsequently sprayed using a nozzle designed with a validated numerical model for cold spray technology. The resulting coatings were evaluated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), micro- and nanoindentation. The TEM analysis shows that the nanocrystalline grain structure of the cryomilled feedstock powder was retained after the cold spray process. A significant increase in hardness from 104 to 261±8 (HV300g) was observed when comparing the nanocrystalline coating with cast, cold-worked, Al 5083. The ability to use cold spray to produce nanocrystalline large deposits was also demonstrated in this work.

Ajdelsztajn, Leonardo; Schoenung, Julie M.; Jodoin, Bertrand; Kim, George E.

2005-03-01

459

Improvements in Cold-Plate Fabrication  

NASA Technical Reports Server (NTRS)

Five improvements are reported in cold-plate fabrication. This cold plate is part of a thermal control system designed to serve on space missions. The first improvement is the merging of the end sheets of the cold plate with the face sheets of the structural honeycomb panel. The cold plate, which can be a brazed assembly, uses the honeycomb face sheet as its end sheet. Thus, when the honeycomb panel is fabricated, the face sheet that is used is already part of the cold plate. In addition to reducing weight, costs, and steps, the main benefit of this invention is that it creates a more structurally sound assembly. The second improvement involves incorporation of the header into the closure bar to pass the fluid to a lower layer. Conventional designs have used a separate header, which increases the geometry of the system. The improvement reduces the geometry, thus allowing the cold plate to fit into smaller area. The third improvement eliminates the need of hose, tube, or manifold to supply the cooling fluid externally. The external arrangement can be easily damaged and is vulnerable to leakage. The new arrangement incorporates an internal fluid transfer tube. This allows the fluid to pass from one cold plate to the other without any exposed external features. The fourth improvement eliminates separate fabrication of cold plate(s) and structural members followed by a process of attaching them to each other. Here, the structural member is made of material that can be brazed just as that of the cold plate. Now the structural member and the cold plate can be brazed at the same time, creating a monolithic unit, and thus a more structurally sound assembly. Finally, the fifth improvement is the elimination of an additional welding step that can damage the braze joints. A tube section, which is usually welded on after the braze process, is replaced with a more structurally sound configuration that can be brazed at the same time as the rest of the cold plate.

Zaffetti, Mark A.; Taddey, Edmund P.; Laurin, Michael B.; Chabebe, Natalia

2012-01-01

460

Photosynthetic microorganisms in cold environments  

NASA Astrophysics Data System (ADS)

The polar regions are considered as a model of extraterrestrial ecosystems. Depending on the average temperature, temperature variation and water availability, these conditions could be used as a model of Mars or Europa (e.g. (Elster and Benson, 2004). Two cases are presented: 1) Stable temperature and water availability The environment of cryosestic communities, i.e. organisms living in snow, is characterized by very stable temperature; the diurnal variations do not exceed 1 -2 ° C (Kváderová, 2010) and a are not usually exposed to freeze/thaw. Water is not usually limiting since the water content could reach up to 54 % (Nedbalová et al., 2008). The windblown sediments are important a source of nutrient and could provide protection against the excess of radiation. The nutrient concentrations in the snow are low are depleted rapidly when massive algal blooms forms. Such environment could be found near Mars polar caps or in Europa ice cover. The snow algae are the most important primary producers in snow. Their adaptation strategy is dependent on the developmental stages; the motile stages avoid the harsh conditions (e.g. high light) and sessile stages acclimatize to actual conditions. The main genera Chlamydomonas and Chloromonas (both Chlorophyta) are psychrophilic. Their growth optimum temperature is lower than 15 ° C and their growth is inhibited at temperatures above 20 ° C. 2) Unstable temperature and water availability The deglaciated surfaces, inhabited by lichen communities, are typical by variation in temper-ature and moisture. The temperature could range several tens ° C within a short time and the water availability is usually very limited. Due to temperature variation, the lichens are subjected to many freeze/thaw cycles. Such environments could be found in Martian deserts. The lichens are symbotic organisms composed of a mycobiont (heterotrophic fungi) and photo-bionts (algae and/or cyanobacteria). Majority of lichens are dehydrated in the field and their physiological processes are inactive. If hydrated, they are physiologically active even at subzero temperatures (Kappen et al., 1996). Although living in cold environments, the growth optimum temperature of typical phycobiont Trebouxia (Chlorophyta) sp. is above 15 ° C, so these algae are considered to be rather psychrotolerant. Acknowledgement The work was supported from projects GA AS CR Nos. KJB 601630808 and KJ KJB600050708, CAREX and long-term institutional research plan of the Institute of Botany AS CR AV0Z600050516 and the Masaryk University. Prof. Martin Backor (Safarik University in Kosice) is kindly ac-knowledged for providing the strains Trebouxia erici and T. glomerata (Backor). References Elster, J. , Benson, E.E. Life in the polar terrestrial environment with a focus on algae and cyanobacteria, in Fuller, B.J., Lane, N. , Benson, E.E. (Eds), Life in the Frozen State. CRC Press, pp. 111-150, 2004. Kappen, L., Schroeter, B., Scheidegger, C., Sommerkorn, M. , Hestmark, G. Cold resistance and metabolic activity of lichens below 0 ° C. Adv. Space Res. 18, 119-128, 1996. Kviderova, J. Characterization of the community of snow algae and their photochemical performance in situ in the Giant Mountains, Czech Republic. Arct. Antarct. Alp. Res. accepted, 2010. Nedbalova, L., Kocianova, M. , Lukavsky, J. Ecology of snow algae in the Giant Mountains and their relation to cryoseston in Europe. Opera Corcontica 45, 59-68, 2008.

Kviderova, Jana; Hajek, Josef; Elster, Josef; Bartak, Milos; Vaczi, Peter; Nedbalova, Linda

461

Probing Nuclear Structure by Cold Emission Processes  

SciTech Connect

Cold emission processes (one and two-proton emission, alpha-decay, heavy cluster emission and cold binary or ternary fission) are presently among important tools to investigate the structure of rare nuclei far from the stability line. We analyze the coupling between collective excitations of the emitted fragments and the relative motion, in terms of the coupled channels technique. It turns out that partial decay widths to excited states of emitted fragments are very sensitive to the nuclear structure details.

Delion, D. S. [Horia Hulubei National Institute of Physics and Nuclear Engineering, 407 Atomistilor, POB MG-6, Bucharest-Magurele (Romania)

2008-01-24

462

Properties of the Central American cold surge  

NASA Technical Reports Server (NTRS)

The Central American cold surge (CACS) is a frontal incursion from the United States into Central America and resembles the East Asian cold surge. They occur more frequently than analyzed by NMC or by published results, based on our observations between 1979 and 1990. Climatology and structure are quantified, based on surface and upper air stations throughout Central America and satellite products from GOES visible and infrared sensors and SSM/I precipitable water and rain rate sensors.

Mcguirk, James P.; Reding, Philip J.; Zhang, Yuxia

1993-01-01

463

Toxicity evaluation and hazard review Cold Smoke  

SciTech Connect

Cold Smoke is a dense white smoke produced by the reaction of titanium tetrachloride and aqueous ammonia aerosols. Early studies on the toxicity of this nonpyrotechnically generated smoke indicated that the smoke itself is essentially non-toxic (i.e. exhibits to systemic toxicity or organ damage due to exposure) under normal deployment conditions. The purpose of this evaluation was to review and summarize the recent literature data available on the toxicity of Cold Smoke, its chemical constituents, and its starting materials.

Archuleta, M.M.; Stocum, W.E.

1993-12-01

464

Drug Living Lab – Cold Chain Monitoring  

Microsoft Academic Search

\\u000a New developments in electronic cold chain management pose challenges to organisations in how they engage in inter-organisational\\u000a interactions. While electronic cold chain innovations offer the promise of safer, more secure, transparent and economical\\u000a life sciences supply chains, their very transparency has implications for process knowledge, cost, and the required organisational\\u000a structures. Advanced sensors and wireless monitoring enable us to capture

Allen Higgins

465

Cold stress induces lower urinary tract symptoms.  

PubMed

Cold stress as a result of whole-body cooling at low environmental temperatures exacerbates lower urinary tract symptoms, such as urinary urgency, nocturia and residual urine. We established a model system using healthy conscious rats to explore the mechanisms of cold stress-induced detrusor overactivity. In this review, we summarize the basic findings shown by this model. Rats that were quickly transferred from room temperature (27 ± 2°C) to low temperature (4 ± 2°C) showed detrusor overactivity including increased basal pressure and decreased voiding interval, micturition volume, and bladder capacity. The cold stress-induced detrusor overactivity is mediated through a resiniferatoxin-sensitve C-fiber sensory nerve pathway involving ?1-adrenergic receptors. Transient receptor potential melastatin 8 channels, which are sensitive to thermal changes below 25-28°C, also play an important role in mediating the cold stress responses. Additionally, the sympathetic nervous system is associated with transient hypertension and decreases of skin surface temperature that are closely correlated with the detrusor overactivity. With this cold stress model, we showed that ?1-adrenergic receptor antagonists have the potential to treat cold stress-exacerbated lower urinary tract symptoms. In addition, we showed that traditional Japanese herbal mixtures composed of Hachimijiogan act, in part, by increasing skin temperature and reducing the number of cold sensitive transient receptor potential melastatin channels in the skin. The effects of herbal mixtures have the potential to treat and/or prevent the exacerbation of lower urinary tract symptoms by providing resistance to the cold stress responses. Our model provides new opportunities for utilizing animal disease models with altered lower urinary tract functions to explore the effects of novel therapeutic drugs. PMID:23441811

Imamura, Tetsuya; Ishizuka, Osamu; Nishizawa, Osamu

2013-07-01

466

On the railway track dynamics with rail vibration absorber for noise reduction  

NASA Astrophysics Data System (ADS)

A promising means to increase the decay rate of vibration along the rail is using a rail absorber for noise reduction. Compound track models with the tuned rail absorber are developed for investigation of the performance of the absorber on vibration reduction. Through analysis of the track dynamics with the rail absorber some guidelines are given on selection of the types and parameters for the rail absorber. It is found that a large active mass used in the absorber is beneficial to increase the decay rate of rail vibration. The effectiveness of the piecewise continuous absorber is moderate compared with the discrete absorber installed in the middle of sleeper span or at a sleeper. The most effective installation position for the discrete absorber is in the middle of sleeper span. Over high or over low loss factor of the damping material used in the absorber may degrade the performance on vibration reduction.

Wu, T. X.

2008-01-01

467

Exchanging Ohmic Losses in Metamaterial Absorbers with Useful Optical Absorption for Photovoltaics  

PubMed Central

Using metamaterial absorbers, we have shown that metallic layers in the absorbers do not necessarily constitute undesired resistive heating problem for photovoltaics. Tailoring the geometric skin depth of metals and employing the natural bulk absorbance characteristics of the semiconductors in those absorbers can enable the exchange of undesired resistive losses with the useful optical absorbance in the active semiconductors. Thus, Ohmic loss dominated metamaterial absorbers can be converted into photovoltaic near-perfect absorbers with the advantage of harvesting the full potential of light management offered by the metamaterial absorbers. Based on experimental permittivity data for indium gallium nitride, we have shown that between 75%–95% absorbance can be achieved in the semiconductor layers of the converted metamaterial absorbers. Besides other metamaterial and plasmonic devices, our results may also apply to photodectors and other metal or semiconductor based optical devices where resistive losses and power consumption are important pertaining to the device performance. PMID:24811322

Vora, Ankit; Gwamuri, Jephias; Pala, Nezih; Kulkarni, Anand; Pearce, Joshua M.; Güney, Durdu Ö.

2014-01-01

468

The Cornell University cold neutron beam facility  

SciTech Connect

The final version of a cold neutron beam facility under development at the Cornell 500-kW TRIGA reactor is nearing completion. The facility will provide an ultra-low background subthermal neutron beam, primarily for nuclear reaction experiments such as (n,gamma) and (n,ce) studies and applications such as prompt gamma neutron activation analysis. Its uses will also include exploration of new cold neutron methods and training of graduate students in cold neutron techniques. The facility employs a 13-m long Curved (500-m radius) Ni-on-glass neutron guide (2 cm x 5 cm) to filter out fast neutrons and gamma rays, location of the guide exit in a room isolated from other beams, cold neutrons to increase transmission through the guide, a mesitylene moderator at ca. 30K that avoids hazards of liquid hydrogen or solid methane, and cooling by Cu cold fingers attached to a cryorefrigerator outside the reactor bulk shield. The mesitylene chamber and the first 3 meters of guide are installed in a standard beamplug shell so that no modifications of the reactor structure were required. Design features of the cold source proper have been published in an article that also describes earlier stages of the project, and more recent design details and extensive subsystem tests are reported elsewhere. Final assembly and testing of the beamplug assembly is Currently underway (June 1994); completion is expected in Fall 1994. The project has involved more than seven graduate and undergraduate students.

Clark, D.D. [Cornell Univ., Ithaca, NY (United States)

1994-12-31

469

TRPA1 contributes to cold hypersensitivity.  

PubMed

TRPA1 is a nonselective cation channel expressed by nociceptors. Although it is widely accepted that TRPA1 serves as a broad irritancy receptor for a variety of reactive chemicals, its role in cold sensation remains controversial. Here, we demonstrate that mild cooling markedly increases agonist-evoked rat TRPA1 currents. In the absence of an agonist, even noxious cold only increases current amplitude slightly. These results suggest that TRPA1 is a key mediator of cold hypersensitivity in pathological conditions in which reactive oxygen species and proinflammatory activators of the channel are present, but likely plays a comparatively minor role in acute cold sensation. Supporting this, cold hypersensitivity can be induced in wild-type but not Trpa1(-/-) mice by subcutaneous administration of a TRPA1 agonist. Furthermore, the selective TRPA1 antagonist HC-030031 [2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)-N-(4-isopropylphenyl)acetamide] reduces cold hypersensitivity in rodent models of inflammatory and neuropathic pain. PMID:21068322

del Camino, Donato; Murphy, Sarah; Heiry, Melissa; Barrett, Lee B; Earley, Taryn J; Cook, Colby A; Petrus, Matt J; Zhao, Michael; D'Amours, Marc; Deering, Nate; Brenner, Gary J; Costigan, Michael; Hayward, Neil J; Chong, Jayhong A; Fanger, Christopher M; Woolf, Clifford J; Patapoutian, Ardem; Moran, Magdalene M

2010-11-10

470

Methods for applying microchannels to separate methane using liquid absorbents, especially ionic liquid absorbents from a mixture comprising methane and nitrogen  

DOEpatents

Methods of using microchannel separation systems including absorbents to improve thermal efficiency and reduce parasitic power loss. Energy is typically added to desorb methane and then energy or heat is removed to absorb methane using a working solution. The working solution or absorbent may comprise an ionic liquid, or other fluids that demonstrate a difference in affinity between methane and nitrogen in a solution.

Tonkovich, Anna Lee Y. (Dublin, OH); Litt, Robert D. (Westerville, OH); Dongming, Qiu (Dublin, OH); Silva, Laura J. (Plain City, OH); Lamont, Micheal Jay (Plain City, OH); Fanelli, Maddalena (Plain City, OH); Simmons, Wayne W. (Plain city, OH); Perry, Steven (Galloway, OH)

2011-10-04

471

Study of flue gas desulfurization absorbent prepared from coal fly ash: Effects of the composition of the absorbent on the activity  

Microsoft Academic Search

The absorbents for SOâ and NO from flue gas were prepared from calcium hydroxide, calcium sulfate, silicic acid, and aluminum hydroxide. The effects of the composition of the absorbent are studied on the activity for the absorption of SOâ and NO on the structure of the absorbent. The activity for the absorption of SOâ and NO markedly increased with the

Hiroaki Tsuchiai; Tomohiro Ishizuka; Hideki Nakamura; Tsutomu Ueno; Hideshi Hattori

1996-01-01

472

First-order optimal linear and nonlinear detuning of centrifugal pendulum vibration absorbers  

NASA Astrophysics Data System (ADS)

Centrifugal pendulum vibration absorbers are used to attenuate steady-state torsional vibrations in rotating and reciprocating machines. In most practical implementations, a set of multiple absorbers is symmetrically arranged on a rotor. Typically, each absorber mass is bifilar suspended, which allows the absorber mass to be moved along a prescribed path. Previous studies have considered how to determine absorber paths in order to obtain absorbers with amplitude-independent frequency known as tautochronic absorbers. It is known that a tautochronic absorber is highly desirable if only one absorber is installed on the rotor. However, in most applications multiple interacting absorbers are installed and as a result symmetry-induced nonlinear instabilities or localization caused by relative imperfections among the absorbers may occur. An effective strategy to avoid such situations is to perturb the tautochronic tuning which has been confirmed in practice and by previous theoretical investigations. This paper presents an approach for detuning a recently developed general tautochronic absorber design. The general design makes it possible to consider a wide class of tautochronic absorbers, e.g. absorbers without bifilar suspensions. The intent of this paper is to extend the existing tautochronic design guideline to non-tautochronic designs. As a result, different absorber designs can be addressed by one uniform theoretical approach, and existing absorber designs are included as special cases. Former studies on detuning of bifilar tautochronic absorbers use a one-parameter family of curves on which the absorber mass rides. Here, however, the detuning is not restricted to a one-parameter family of curves, which makes it possible to either optimize system performance or to avoid asynchronous absorber responses. In the case of synchronously responding equal absorbers, a necessary condition for optimal performance is derived analytically. Further, it is shown that asynchronous responses can be avoided by applying positive detuning.

Mayet, J.; Ulbrich, H.

2015-01-01

473

Quantitative determination of absorbed hydrogen in oxidised zircaloy by means of neutron radiography  

NASA Astrophysics Data System (ADS)

Hydrogen absorbed in steam-oxidised zircaloy can be determined quantitatively by means of neutron radiography. Correlation parameters between the total cross section and hydrogen content as well as oxide layer thickness were determined quantitatively. At H/Zr atomic ratios lower than 1.0, linear correlations between the hydrogen content and total cross section exist. The total cross section of Zr is lower and the effect of the hydrogen is higher in radiography measurements with a cold neutron spectrum than with a thermal spectrum. A Be filter reduces the effects of lower wavelength and epithermal neutrons and extends the linear correlations to higher H/Zr atomic ratios. Due to the better possibilities of background corrections, the neutron image should be detected by a CCD camera for a proper quantitative analysis with a medium spatial resolution of about 0.1 mm. A higher spatial resolution, but larger uncertainties in the quantitative hydrogen determination are achieved by measurements with imaging plates. The effect of oxygen layers on the total cross section is much smaller than the effect of hydrogen. The total cross section measured depends linearly on the oxide layer thickness.

Grosse, M.; Lehmann, E.; Vontobel, P.; Steinbrueck, M.

2006-10-01

474

Interannual Variation of the East Asian Cold Surge Activity  

Microsoft Academic Search

The occurrence frequency of the east Asian cold surge exhibits an interannual variation in concert with the El Niño Southern Oscillation (ENSO) cycle. That is, the cold surge occurs more (less) frequently during warm (cold) ENSO winters. Because the cold surge high low dipoles are coupled with the upper-level synoptic short waves, any mechanism modulating the activity of these waves

Tsing-Chang Chen; Wan-Ru Huang; Jin-Ho Yoon

2004-01-01

475

Research on the security of cold-chain logistics  

Microsoft Academic Search

In this paper, the definition of cold-chain logistics and security features are analyzed. Based on overview of China's cold-chain logistics, cold chain, through the status quo at home and abroad contrast, we present some of China's food chain problems. With security control system of thought, and risk management theory, the establishment of a more comprehensive evaluation of cold chain logistics

Guojun Ji; Rong Guo

2009-01-01

476

Gold-black as IR Absorber and Solar Cell Enhancer  

SciTech Connect

Infrared absorbance and visible/near-IR excited plasmon resonances are investigated in gold-black, a porous nano-structured conducting film. A two level full factorial optimization study with evaporation-chamber pressure, boat current, substrate temperature, and degree of polymer infusion (for hardening) was performed. Polymer infusion was found generally to reduce absorbance in the long wave IR but has little effect at THz wavelengths, although for samples with the highest absorbance there is a slight improvement in the absorbance figure of merit (FOM) in both wavelength regimes. The characteristic length scales of the structured films vary considerably as a function of deposition parameters, but the IR FOM is found to be only weakly correlated with these distributions, which are determined by wavelet analysis of scanning electron micrographs images. Initial investigations of gold-black by photoelectron emission microscopy (PEEM) reveal plasmon resonances, which have potential to enhance the efficiency of thin film solar cells. For films with different characteristic length scales, the plasmon resonances appear in portions of the film with similar length scales.

Peale, Robert E.; Cleary, Justin W.; Ishimaru, Manabu; Smith, C. W.; Baillie, K.; Colwell, J. E.; Beck, Kenneth M.; Joly, Alan G.; Edwards, Oliver; Fredricksen, C. J.

2010-03-01

477

Design optimization of a damped hybrid vibration absorber  

NASA Astrophysics Data System (ADS)

In this article, the H? optimization design of a hybrid vibration absorber (HVA), including both passive and active elements, for the minimization of the resonant vibration amplitude of a single degree-of-freedom (sdof) vibrating structure is derived by using the fixed-points theory. The optimum tuning parameters are the feedback gain, the tuning frequency, damping and mass ratios of the absorber. The effects of these parameters on the vibration reduction of the primary structure are revealed based on the analytical model. Design parameters of both passive and active elements of the HVA are optimized for the minimization of the resonant vibration amplitude of the primary system. One of the inherent limitations of the traditional passive vibration absorber is that its vibration absorption is low if the mass ratio between the absorber mass and the mass of the primary structure is low. The proposed HVA overcomes this limitation and provides very good vibration reduction performance even at a low mass ratio. The proposed optimized HVA is compared to a recently published HVA designed for similar propose and it shows that the present design requires less energy for the active element of the HVA than the compared design.

Cheung, Y. L.; Wong, W. O.; Cheng, L.

2012-02-01

478

A Monte Carlo evaluation of three Compton camera absorbers.  

PubMed

We present a quantitative study on the performance of cadmium zinc telluride (CZT), thallium-doped sodium iodide (NaI(Tl)) and germanium (Ge) detectors as potential Compton camera absorbers. The GEANT4 toolkit was used to model the performance of these materials over the nuclear medicine energy range. CZT and Ge demonstrate the highest and lowest efficiencies respectively. Although the best spatial resolution was attained for Ge, its lowest ratio of single photoelectric to multiple interactions suggests that it is most prone to inter-pixel cross-talk. In contrast, CZT, which demonstrates the least positioning error due to multiple interactions, has a comparable spatial resolution with Ge. Therefore, we modelled a Compton camera system based on silicon (Si) and CZT as the scatterer and absorber respectively. The effects of the detector parameters of our proposed system on image resolution were evaluated and our results show good agreement with previous studies. Interestingly, spatial resolution which accounted for the least image degradation at 140.5 keV became the dominant degrading factor at 511 keV, indicating that the absorber parameters play some key roles at higher energies. The results of this study have validated the predictions by An et al. which state that the use of a higher energy gamma source together with reduction of the absorber segmentation to sub-millimetre could achieve the image resolution of 5 mm required in medical imaging. PMID:21710232

Uche, C Z; Round, W H; Cree, M J

2011-09-01

479

FDTD Modeling of Absorbing Materials for EMI Applications  

E-print Network

FDTD Modeling of Absorbing Materials for EMI Applications Jianfeng Xu#1 , Marina Y. Koledintseva#2 electromagnetic inference (EMI) are analyzed in this paper using a full-wave 3D finite-difference time experiments, and the good agreement is obtained. I. INTRODUCTION Electromagnetic interference (EMI) issues can

Koledintseva, Marina Y.

480

The Decorated Tapered Chain as a Granular Shock Absorber  

Microsoft Academic Search

A 1D alignment of progressively shrinking spherical grains (a tapered chain) turns out to be an excellent impulse absorber with rich nonlinear dynamical behavior. Here we discuss a tapered chain with interstitial grains between every sphere of the original tapered chain and demonstrate analytically (using the hard sphere approximation), numerically and experimentally that the shock absorption ability of the ``decorated\\

Robert Doney; Surajit Sen; Dorian Dicocco

2006-01-01

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