X-RAY AND MULTIWAVELENGTH INSIGHTS INTO THE NATURE OF WEAK EMISSION-LINE QUASARS AT LOW REDSHIFT

International Nuclear Information System (INIS)

Wu Jianfeng; Brandt, W. N.; Schneider, Donald P.; Anderson, Scott F.; Diamond-Stanic, Aleksandar M.; Hall, Patrick B.; Plotkin, Richard M.; Shemmer, Ohad

2012-01-01

We report on the X-ray and multiwavelength properties of 11 radio-quiet quasars with weak or no emission lines identified by the Sloan Digital Sky Survey (SDSS) with redshift z = 0.4-2.5. Our sample was selected from the Plotkin et al. catalog of radio-quiet, weak-featured active galactic nuclei (AGNs). The distribution of relative X-ray brightness for our low-redshift weak-line quasar (WLQ) candidates is significantly different from that of typical radio-quiet quasars, having an excess of X-ray weak sources, but it is consistent with that of high-redshift WLQs. Over half of the low-redshift WLQ candidates are X-ray weak by a factor of ∼> 5, compared to a typical SDSS quasar with similar UV/optical luminosity. These X-ray weak sources generally show similar UV emission-line properties to those of the X-ray weak quasar PHL 1811 (weak and blueshifted high-ionization lines, weak semiforbidden lines, and strong UV Fe emission); they may belong to the notable class of PHL 1811 analogs. The average X-ray spectrum of these sources is somewhat harder than that of typical radio-quiet quasars. Several other low-redshift WLQ candidates have normal ratios of X-ray-to-optical/UV flux, and their average X-ray spectral properties are also similar to those of typical radio-quiet quasars. The X-ray weak and X-ray normal WLQ candidates may belong to the same subset of quasars having high-ionization 'shielding gas' covering most of the wind-dominated broad emission-line region, but be viewed at different inclinations. The mid-infrared-to-X-ray spectral energy distributions (SEDs) of these sources are generally consistent with those of typical SDSS quasars, showing that they are not likely to be BL Lac objects with relativistically boosted continua and diluted emission lines. The mid-infrared-to-UV SEDs of most radio-quiet weak-featured AGNs without sensitive X-ray coverage (34 objects) are also consistent with those of typical SDSS quasars. However, one source in our X

Weak hard X-ray emission from broad absorption line quasars: evidence for intrinsic X-ray weakness

International Nuclear Information System (INIS)

Luo, B.; Brandt, W. N.; Scott, A. E.; Alexander, D. M.; Gandhi, P.; Stern, D.; Teng, S. H.; Arévalo, P.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Comastri, A.; Farrah, D.; Hailey, C. J.; Harrison, F. A.; Koss, M.; Ogle, P.; Puccetti, S.; Saez, C.

2014-01-01

We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z < 1.3. However, their rest-frame ≈2 keV luminosities are 14 to >330 times weaker than expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three are not detected. The hard X-ray (8-24 keV) weakness observed by NuSTAR requires Compton-thick absorption if these objects have nominal underlying X-ray emission. However, a soft stacked effective photon index (Γ eff ≈ 1.8) for this sample disfavors Compton-thick absorption in general. The uniform hard X-ray weakness observed by NuSTAR for this and the pilot samples selected with <10 keV weakness also suggests that the X-ray weakness is intrinsic in at least some of the targets. We conclude that the NuSTAR observations have likely discovered a significant population (≳ 33%) of intrinsically X-ray weak objects among the BAL quasars with significantly weak <10 keV emission. We suggest that intrinsically X-ray weak quasars might be preferentially observed as BAL quasars.

Weak Hard X-Ray Emission from Broad Absorption Line Quasars: Evidence for Intrinsic X-Ray Weakness

DEFF Research Database (Denmark)

Luo, B.; Brandt, W. N.; Alexander, D. M.

2014-01-01

We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z 330 times weaker than...... expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL...... quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three...

NuSTAR reveals an intrinsically x-ray weak broad absorption line quasar in the ultraluminous infrared galaxy Markarian 231

DEFF Research Database (Denmark)

Teng, Stacy H.; Brandt, W. N.; Harrison, F. A.

2014-01-01

-ionization broad absorption line quasar that is intrinsically X-ray weak. The weak ionizing continuum may explain the lack of mid-infrared [O IV], [Ne V], and [Ne VI] fine-structure emission lines which are present in sources with otherwise similar AGN properties. We argue that the intrinsic X-ray weakness may...

Spectroscopic and polarimetric study of radio-quiet weak emission line quasars

Science.gov (United States)

Kumar, Parveen; Chand, Hum; Gopal-Krishna; Srianand, Raghunathan; Stalin, Chelliah Subramonian; Petitjean, Patrick

2018-04-01

A small subset of optically selected radio-quiet QSOs with weak or no emission lines may turn out to be the elusive radio-quiet BL Lac objects, or simply be radio-quiet QSOs with an infant/shielded broad line region (BLR). High polarisation (p > 3-4%), a hallmark of BL Lacs, can be used to test whether some optically selected ‘radio-quiet weak emission line QSOs’ (RQWLQs) show a fractional polarisation high enough to qualify as radio-quiet analogues of BL Lac objects. To check this possibility, we have made optical spectral and polarisation measurements of a sample of 19 RQWLQs. Out of these, only 9 sources show a non-significant proper motion (hence very likely extragalactic) and only two of them are found to have p > 1%. For these two RQWLQs, namely J142505.59+035336.2 and J154515.77+003235.2, we found the highest polarization to be 1.59±0.53%, which is again too low to classify them as (radio-quiet) BL Lacs, although one may recall that even genuine BL Lacs sometimes appear weakly polarised. We also present a statistical comparison of the optical spectral index, for a sample of 45 RQWLQs with redshift-luminosity matched control samples of 900 QSOs and an equivalent sample of 120 blazars, assembled from the literature. The spectral index distribution of RQWLQs is found to differ, at a high significance level, from that of blazars. This, too, is consistent with the common view that the mechanism of the central engine in RQWLQs, as a population, is close to that operating in normal QSOs and the primary difference between them is related to the BLR.

MULTIWAVELENGTH OBSERVATIONS OF RADIO-QUIET QUASARS WITH WEAK EMISSION LINES

International Nuclear Information System (INIS)

Plotkin, Richard M.; Anderson, Scott F.; MacLeod, Chelsea L.; Brandt, W. N.; Schneider, Donald P.; Diamond-Stanic, Aleksandar M.; Fan Xiaohui; Shemmer, Ohad

2010-01-01

We present radio and X-ray observations, as well as optical light curves, for a subset of 26 BL Lac candidates from the Sloan Digital Sky Survey (SDSS) lacking strong radio emission and with z < 2.2. Half of these 26 objects are shown to be stars, galaxies, or absorbed quasars. We conclude that the other 13 objects are active galactic nuclei (AGNs) with abnormally weak emission features; 10 of those 13 are definitively radio quiet, and, for those with available optical light curves, their level of optical flux variability is consistent with radio-quiet quasars. We cannot exclude the possibility that some of these 13 AGNs lie on the extremely radio-faint tail of the BL Lac distribution, but our study generally supports the notion that all BL Lac objects are radio-loud. These radio-quiet AGNs appear to have intrinsically weak or absent broad emission line regions (BELRs), and, based on their X-ray properties, we argue that some are low-redshift analogs to weak line quasars (WLQs). SDSS BL Lac searches are so far the only systematic surveys of the SDSS database capable of recovering such exotic low-redshift WLQs. There are 71 more z < 2.2 radio-quiet BL Lac candidates already identified in the SDSS, but not considered here, and many of those might be best unified with WLQs as well. Future studies combining low- and high-redshift WLQ samples will yield new insight on our understanding of the structure and formation of AGN BELRs.

Electromigration-induced plastic deformation in passivated metal lines

Science.gov (United States)

Valek, B. C.; Bravman, J. C.; Tamura, N.; MacDowell, A. A.; Celestre, R. S.; Padmore, H. A.; Spolenak, R.; Brown, W. L.; Batterman, B. W.; Patel, J. R.

2002-11-01

We have used scanning white beam x-ray microdiffraction to study microstructural evolution during an in situ electromigration experiment on a passivated Al(Cu) test line. The data show plastic deformation and grain rotations occurring under the influence of electromigration, seen as broadening, movement, and splitting of reflections diffracted from individual metal grains. We believe this deformation is due to localized shear stresses that arise due to the inhomogeneous transfer of metal along the line. Deviatoric stress measurements show changes in the components of stress within the line, including relaxation of stress when current is removed.

The SLUGGS survey: globular cluster stellar population trends from weak absorption lines in stacked spectra

Science.gov (United States)

Usher, Christopher; Forbes, Duncan A.; Brodie, Jean P.; Romanowsky, Aaron J.; Strader, Jay; Conroy, Charlie; Foster, Caroline; Pastorello, Nicola; Pota, Vincenzo; Arnold, Jacob A.

2015-01-01

As part of the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, we stack 1137 Keck DEIMOS (Deep Imaging Multi-Object Spectrograph) spectra of globular clusters from 10 galaxies to study their stellar populations in detail. The stacked spectra have median signal-to-noise ratios of ˜90 Å-1. Besides the calcium triplet, we study weaker sodium, magnesium, titanium and iron lines as well as the Hα and higher order Paschen hydrogen lines. In general, the stacked spectra are consistent with old ages and a Milky Way-like initial mass function. However, we see different metal line index strengths at fixed colour and magnitude, and differences in the calcium triplet-colour relation from galaxy to galaxy. We interpret this as strong evidence for variations in the globular cluster colour-metallicity relation between galaxies. Two possible explanations for the colour-metallicity relation variations are that the average ages of globular clusters vary from galaxy to galaxy or that the average abundances of light elements (i.e. He, C, N and O) differ between galaxies. Stacking spectra by magnitude, we see that the colours become redder and metal line indices stronger with brighter magnitudes. These trends are consistent with the previously reported `blue tilts' being mass-metallicity relations.

A Survey of Metal Lines at High Redshift. II. SDSS Absorption Line Studies—O VI Line Density, Space Density, and Gas Metallicity at z abs ~ 3.0

Science.gov (United States)

Frank, S.; Mathur, S.; Pieri, M.; York, D. G.

2010-09-01

We have analyzed a large data set of O VI absorber candidates found in the spectra of 3702 Sloan Digital Sky Survey (SDSS) quasars, focusing on a subsample of 387 active galactic nuclei sight lines with an average S/N >=5.0, allowing for the detection of absorbers above a rest-frame equivalent width limit of W r >= 0.19 Å for the O VI 1032 Å component. Accounting for random interlopers mimicking an O VI doublet, we derive for the first time a secure lower limit for the redshift number density ΔN/Δz for redshifts z abs >= 2.8. With extensive Monte Carlo simulations, we quantify the losses of absorbers due to blending with the ubiquitous Lyα forest lines and estimate the success rate of retrieving each individual candidate as a function of its redshift, the emission redshift of the quasar, the strength of the absorber, and the measured signal-to-noise ratio (S/N) of the spectrum by modeling typical Lyman forest spectra. These correction factors allow us to derive the "incompleteness and S/N-corrected" redshift number densities of O VI absorbers: ΔN O VI,c /Δzc (2.8 secure lower limit for the contribution of O VI to the closure mass density at the redshifts probed here: ΩO VI (2.8 = 1.9 × 10-8 h -1. We show that the strong lines we probe account for over 65% of the mass in the O VI absorbers; the weak absorbers, while dominant in line number density, do not contribute significantly to the mass density. Making a conservative assumption about the ionization fraction, {O VI}/{O}, and adopting the Anders & Grevesse solar abundance values, we derive the mean metallicity of the gas probed in our search: ζ(2.8 = 3.6 × 10-4 h, in good agreement with other studies. These results demonstrate that large spectroscopic data sets such as SDSS can play an important role in QSO absorption line studies, in spite of the relatively low resolution.

A SURVEY OF METAL LINES AT HIGH REDSHIFT. II. SDSS ABSORPTION LINE STUDIES-O VI LINE DENSITY, SPACE DENSITY, AND GAS METALLICITY AT zabs ∼ 3.0

International Nuclear Information System (INIS)

Frank, S.; Mathur, S.; Pieri, M.; York, D. G.

2010-01-01

We have analyzed a large data set of O VI absorber candidates found in the spectra of 3702 Sloan Digital Sky Survey (SDSS) quasars, focusing on a subsample of 387 active galactic nuclei sight lines with an average S/N ≥5.0, allowing for the detection of absorbers above a rest-frame equivalent width limit of W r ≥ 0.19 A for the O VI 1032 A component. Accounting for random interlopers mimicking an O VI doublet, we derive for the first time a secure lower limit for the redshift number density ΔN/Δz for redshifts z abs ≥ 2.8. With extensive Monte Carlo simulations, we quantify the losses of absorbers due to blending with the ubiquitous Lyα forest lines and estimate the success rate of retrieving each individual candidate as a function of its redshift, the emission redshift of the quasar, the strength of the absorber, and the measured signal-to-noise ratio (S/N) of the spectrum by modeling typical Lyman forest spectra. These correction factors allow us to derive the 'incompleteness and S/N-corrected' redshift number densities of O VI absorbers: ΔN O V I,c /Δz c (2.8 O V I,c /Δz c (3.2 O V I,c /Δz c (3.6 O V I (2.8 -8 h -1 . We show that the strong lines we probe account for over 65% of the mass in the O VI absorbers; the weak absorbers, while dominant in line number density, do not contribute significantly to the mass density. Making a conservative assumption about the ionization fraction, O VI /O, and adopting the Anders and Grevesse solar abundance values, we derive the mean metallicity of the gas probed in our search: ζ(2.8 -4 h, in good agreement with other studies. These results demonstrate that large spectroscopic data sets such as SDSS can play an important role in QSO absorption line studies, in spite of the relatively low resolution.

Weak Hard X-Ray Emission from Two Broad Absorption Line Quasars Observed with NuStar: Compton-Thick Absorption or Intrinsic X-Ray Weakness?

Science.gov (United States)

Luo, B.; Brandt, W. N.; Alexander, D. M.; Harrison, F. A.; Stern, D.; Bauer, F. E.; Boggs, S. E.; Christensen, F. E.; Comastri, A.; Craig, W. W..;

WEAK HARD X-RAY EMISSION FROM TWO BROAD ABSORPTION LINE QUASARS OBSERVED WITH NuSTAR: COMPTON-THICK ABSORPTION OR INTRINSIC X-RAY WEAKNESS?

Energy Technology Data Exchange (ETDEWEB)

Luo, B.; Brandt, W. N. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Alexander, D. M.; Hickox, R. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Harrison, F. A.; Fuerst, F.; Grefenstette, B. W.; Madsen, K. K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Bauer, F. E. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Boggs, S. E.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, F. E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Comastri, A. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Fabian, A. C. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Fiore, F. [Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone (Italy); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Matt, G. [Dipartimento di Matematica e Fisica, Universita degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); Ogle, P. [IPAC, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States); and others

2013-08-01

We present Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain Almost-Equal-To 400-600 hard X-ray ({approx}> 10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed (N{sub H} {approx}< 10{sup 24} cm{sup -2}). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain the column densities for both to be N{sub H} Almost-Equal-To 7 Multiplication-Sign 10{sup 24} cm{sup -2} if the weak hard X-ray emission is caused by obscuration from the shielding gas. We discuss a few possibilities for how PG 1004+130 could have Compton-thick shielding gas without strong Fe K{alpha} line emission; dilution from jet-linked X-ray emission is one likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place statistical constraints upon the fraction of intrinsically X-ray weak BAL quasars; this fraction is likely 17%-40%.

V819 TAU: A RARE WEAK-LINED T TAURI STAR WITH A WEAK INFRARED EXCESS

International Nuclear Information System (INIS)

Furlan, E.; Forrest, W. J.; Manoj, P.; Kim, K. H.; Watson, Dan M.; Sargent, B. A.

2009-01-01

We use Spitzer data to infer that the small infrared excess of V819 Tau, a weak-lined T Tauri star in Taurus, is real and not attributable to a 'companion' 10'' to the south. We do not confirm the mid-infrared excess in HBC 427 and V410 X-ray 3, which are also non-accreting T Tauri stars in the same region; instead, for the former object, the excess arises from a red companion 9'' to the east. A single-temperature blackbody fit to the continuum excess of V819 Tau implies a dust temperature of 143 K; however, a better fit is achieved when the weak 10 and 20 μm silicate emission features are also included. We infer a disk of sub-μm silicate grains between about 1 AU and several 100 AU with a constant surface density distribution. The mid-infrared excess of V819 Tau can be successfully modeled with dust composed mostly of small amorphous olivine grains at a temperature of 85 K, and most of the excess emission is optically thin. The disk could still be primordial, but gas-poor and therefore short-lived, or already at the debris disk stage, which would make it one of the youngest debris disk systems known.

The Frequency of Intrinsic X-Ray Weakness among Broad Absorption Line Quasars

Science.gov (United States)

Liu, Hezhen; Luo, B.; Brandt, W. N.; Gallagher, S. C.; Garmire, G. P.

2018-06-01

We present combined ≈14–37 ks Chandra observations of seven z = 1.6–2.7 broad absorption line (BAL) quasars selected from the Large Bright Quasar Survey (LBQS). These seven objects are high-ionization BAL (HiBAL) quasars, and they were undetected in the Chandra hard band (2–8 keV) in previous observations. The stacking analyses of previous Chandra observations suggested that these seven objects likely contain some candidates for intrinsically X-ray weak BAL quasars. With the new Chandra observations, six targets are detected. We calculate their effective power-law photon indices and hard-band flux weakness, and find that two objects, LBQS 1203+1530 and LBQS 1442–0011, show soft/steep spectral shapes ({{{Γ }}}eff}={2.2}-0.9+0.9 and {1.9}-0.8+0.9) and significant X-ray weakness in the hard band (by factors of ≈15 and 12). We conclude that the two HiBAL quasars are good candidates for intrinsically X-ray weak BAL quasars. The mid-infrared-to-ultraviolet spectral energy distributions of the two candidates are consistent with those of typical quasars. We constrain the fraction of intrinsically X-ray weak active galactic nuclei (AGNs) among HiBAL quasars to be ≈7%–10% (2/29–3/29), and we estimate it is ≈6%–23% (2/35–8/35) among the general BAL quasar population. Such a fraction is considerably larger than that among non-BAL quasars, and we suggest that intrinsically X-ray weak quasars are preferentially observed as BAL quasars. Intrinsically X-ray weak AGNs likely comprise a small minority of the luminous type 1 AGN population, and they should not affect significantly the completeness of these AGNs found in deep X-ray surveys.

Applications of on-line weak affinity interactions in free solution capillary electrophoresis

DEFF Research Database (Denmark)

Heegaard, Niels H H; Nissen, Mogens H; Chen, David D Y

2002-01-01

The impressive selectivity offered by capillary electrophoresis can in some cases be further increased when ligands or additives that engage in weak affinity interactions with one or more of the separated analytes are added to the electrophoresis buffer. This on-line affinity capillary...... electrophoresis approach is feasible when the migration of complexed molecules is different from the migration of free molecules and when separation conditions are nondenaturing. In this review, we focus on applying weak interactions as tools to enhance the separation of closely related molecules, e.g., drug...... enantiomers and on using capillary electrophoresis to characterize such interactions quantitatively. We describe the equations for binding isotherms, illustrate how selectivity can be manipulated by varying the additive concentrations, and show how the methods may be used to estimate binding constants. On...

OXYGEN METALLICITY DETERMINATIONS FROM OPTICAL EMISSION LINES IN EARLY-TYPE GALAXIES

International Nuclear Information System (INIS)

Athey, Alex E.; Bregman, Joel N.

2009-01-01

We measured the oxygen abundances of the warm (T ∼ 10 4 K) phase of gas in seven early-type galaxies through long-slit observations. A template spectra was constructed from galaxies void of warm gas and subtracted from the emission-line galaxies, allowing for a clean measurement of the nebular lines. The ratios of the emission lines are consistent with photoionization, which likely originates from the ultraviolet flux of postasymototic giant branch stars. We employ H II region photoionization models to determine a mean oxygen metallicity of 1.01 ± 0.50 solar for the warm interstellar medium (ISM) in this sample. This warm ISM 0.5-1.5 solar metallicity is consistent with modern determinations of the metallicity in the hot (T ∼ 10 6 -10 7 K) ISM and the upper range of this warm ISM metallicity is consistent with stellar population metallicity determinations. A solar metallicity of the warm ISM favors an internal origin for the warm ISM such as asymptotic giant branch mass loss within the galaxy.

Magnetic circular dichroism spectroscopy of weakly exchange coupled transition metal dimers: A model study

DEFF Research Database (Denmark)

Piligkos, S.; Slep, L.D.; Weyhermuller, T.

2009-01-01

bands of the minority spin Ni(II) ligand field bands were observed to change sign relative to the parent complex 2. This behavior has been analyzed. The present work hence provides a benchmark study for the application of MCD spectroscopy to weakly interacting transition metal dinners. (C) 2008 Elsevier...

HDE 245059: A WEAK-LINED T TAURI BINARY REVEALED BY CHANDRA AND KECK

International Nuclear Information System (INIS)

Baldovin-Saavedra, C.; Audard, M.; Duchene, G.; Guedel, M.; Skinner, S.L.; Paerels, F. B. S.; Ghez, A.; McCabe, C.

2009-01-01

We present the Chandra High Energy Transmission Grating Spectrometer and Keck observations of HDE 245059, a young weak-lined T Tauri star (WTTS), member of the pre-main-sequence group in the λ Orionis Cluster. Our high spatial resolution, near-infrared observations with Keck reveal that HDE 245059 is in fact a binary separated by 0.''87, probably composed of two WTTS based on their color indices. Based on this new information we have obtained an estimate of the masses of the binary components; ∼3 M sun and ∼2.5 M sun for the north and south components, respectively. We have also estimated the age of the system to be ∼2-3 Myr. We detect both components of the binary in the zeroth-order Chandra image and in the grating spectra. The light curves show X-ray variability of both sources and in particular a flaring event in the weaker southern component. The spectra of both stars show similar features: a combination of cool and hot plasma as demonstrated by several iron lines from Fe XVII to Fe XXV and a strong bremsstrahlung continuum at short wavelengths. We have fitted the combined grating and zeroth-order spectrum (considering the contribution of both stars) in XSPEC. The coronal abundances and emission measure distribution for the binary have been obtained using different methods, including a continuous emission measure distribution and a multi-temperature approximation. In all cases we have found that the emission is dominated by plasma between ∼8 and ∼15 MK a soft component at ∼4 MK and a hard component at ∼50 MK are also detected. The value of the hydrogen column density was low, N H ∼ 8 x 10 19 cm -2 , likely due to the clearing of the inner region of the λ Orionis cloud, where HDE 245059 is located. The abundance pattern shows an inverse first ionization potential effect for all elements from O to Fe, the only exception being Ca. To obtain the properties of the binary components, a 3-T model was fitted to the individual zeroth-order spectra

Induced voltages in metallic pipelines near power transmission lines

International Nuclear Information System (INIS)

Grcev, Leonid; Jankov, Voislav; Filiposki, Velimir

2002-01-01

With the continuous development of the electric power system and the pipeline networks used to convey oil or natural gas, cases of close proximity of high voltage structures and metallic pipelines become more and more frequent. Accordingly there is a growing concern about possible hazards resulting from voltages induced in the metallic pipelines by magnetic coupling with nearby power transmission lines. This paper presents a methodology for computation of the induced voltages in buried isolated metallic pipelines. A practical example of computation is also presented. (Author)

The Mean Metal-line Absorption Spectrum of Damped Ly α Systems in BOSS

Energy Technology Data Exchange (ETDEWEB)

Mas-Ribas, Lluís [Institute of Theoretical Astrophysics, University of Oslo, Postboks 1029, NO-0315 Oslo (Norway); Miralda-Escudé, Jordi; Pérez-Ràfols, Ignasi; Arinyo-i-Prats, Andreu [Institut de Ciències del Cosmos, Universitat de Barcelona (UB-IEEC), Barcelona E-08028, Catalonia (Spain); Noterdaeme, Pasquier; Petitjean, Patrick [Institut d’Astrophysique de Paris, UPMC and CNRS, UMR7095 98bis Boulevard Arago, F-75014—Paris (France); Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); York, Donald G. [Department of Astronomy and Astrophysics and the Enrico Fermi Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Ge, Jian, E-mail: l.m.ribas@astro.uio.no [Department of Astronomy, University of Florida, Bryant Space Science Center, Gainesville, FL 32611-2055 (United States)

2017-09-01

We study the mean absorption spectrum of the Damped Ly α (DLA) population at z ∼ 2.6 by stacking normalized, rest-frame-shifted spectra of ∼27,000 DLA systems from the DR12 of the Baryon Oscillation Spectroscopic Survey (BOSS)/SDSS-III. We measure the equivalent widths of 50 individual metal absorption lines in five intervals of DLA hydrogen column density, five intervals of DLA redshift, and overall mean equivalent widths for an additional 13 absorption features from groups of strongly blended lines. The mean equivalent width of low-ionization lines increases with N {sub H} {sub i}, whereas for high-ionization lines the increase is much weaker. The mean metal line equivalent widths decrease by a factor ∼1.1–1.5 from z ∼ 2.1 to z ∼ 3.5, with small or no differences between low- and high-ionization species. We develop a theoretical model, inspired by the presence of multiple absorption components observed in high-resolution spectra, to infer mean metal column densities from the equivalent widths of partially saturated metal lines. We apply this model to 14 low-ionization species and to Al iii, S iii, Si iii, C iv, Si iv, N v, and O vi. We use an approximate derivation for separating the equivalent width contributions of several lines to blended absorption features, and infer mean equivalent widths and column densities from lines of the additional species N i, Zn ii, C ii*, Fe iii, and S iv. Several of these mean column densities of metal lines in DLAs are obtained for the first time; their values generally agree with measurements of individual DLAs from high-resolution, high signal-to-noise ratio spectra when they are available.

Integration of a hydraulic production plant in a weak power system on a long radial line

Energy Technology Data Exchange (ETDEWEB)

Lariviere, P. [Hydro-Quebec TransEnergie, 5655 de Marseille, Montreal, Quebec (Canada); Racine, M. [Hydro-Quebec TransEnergie, C.P. 10 000, Montreal, Quebec (Canada)

2009-03-15

Integrating power plants on long lines and weak power systems requires some care. To this effect, a study was conducted to determine if severe disturbances could result when a hydraulic production plant is integrated along a very long radial transmission line. Frequency responses were evaluated to identify possible resonant system operating conditions. Many events such as faults, transformer energyzing and line opening were investigated. All power plant synchronous machines were represented including exciter and governor regulators. Impact of dynamic modeling of the load was examined. The study demonstrates that the overall protective strategy implemented will limit worst overvoltage constraints imposed to equipment and load within an acceptable level. (author)

Weak acid extractable metals in Bramble Bay, Queensland, Australia: temporal behaviour, enrichment and source apportionment.

Science.gov (United States)

Brady, James P; Ayoko, Godwin A; Martens, Wayde N; Goonetilleke, Ashantha

2015-02-15

Sediment samples were taken from six sampling sites in Bramble Bay, Queensland, Australia between February and November in 2012. They were analysed for a range of heavy metals including Al, Fe, Mn, Ti, Ce, Th, U, V, Cr, Co, Ni, Cu, Zn, As, Cd, Sb, Te, Hg, Tl and Pb. Fraction analysis, Enrichment Factors and Principal Component Analysis-Absolute Principal Component Scores (PCA-APCS) were carried out in order to assess metal pollution, potential bioavailability and source apportionment. Cr and Ni exceeded the Australian Interim Sediment Quality Guidelines at some sampling sites, while Hg was found to be the most enriched metal. Fraction analysis identified increased weak acid soluble Hg and Cd during the sampling period. Source apportionment via PCA-APCS found four sources of metals pollution, namely, marine sediments, shipping, antifouling coatings and a mixed source. These sources need to be considered in any metal pollution control measure within Bramble Bay. Copyright © 2014 Elsevier Ltd. All rights reserved.

X-ray spectral line coincidences between fluorine VIII (and IX) and transition metal lines

International Nuclear Information System (INIS)

Charatis, G.; Rockett, P.D.; Burkhalter, P.G.

1983-01-01

X-ray spectroscopy was performed in the 12 to 15 A region, recording L-shell lines from selected laser-irradiated transition metals. Line coincidences and near coincidences were identified between Fe, Cr, Mn, and Ni L-spectra, and F VIII and F IX K-shell lines. Wavelengths were determined to accuracies of 1 to 3 mA and will be utilized in selecting potential pumping candidates in future x-ray lasing schemes. High-resolution x-ray spectra were collected under controlled illumination and target conditions using 1.05 μm and 0.527 μm laser excitation with the KMS CHROMA laser

Selective removal of heavy metals from metal-bearing wastewater in a cascade line reactor.

Science.gov (United States)

Pavlović, Jelena; Stopić, Srećko; Friedrich, Bernd; Kamberović, Zeljko

2007-11-01

This paper is a part of the research work on 'Integrated treatment of industrial wastes towards prevention of regional water resources contamination - INTREAT' the project. It addresses the environmental pollution problems associated with solid and liquid waste/effluents produced by sulfide ore mining and metallurgical activities in the Copper Mining and Smelting Complex Bor (RTB-BOR), Serbia. However, since the minimum solubility for the different metals usually found in the polluted water occurs at different pH values and the hydroxide precipitates are amphoteric in nature, selective removal of mixed metals could be achieved as the multiple stage precipitation. For this reason, acid mine water had to be treated in multiple stages in a continuous precipitation system-cascade line reactor. All experiments were performed using synthetic metal-bearing effluent with chemical a composition similar to the effluent from open pit, Copper Mining and Smelting Complex Bor (RTB-BOR). That effluent is characterized by low pH (1.78) due to the content of sulfuric acid and heavy metals, such as Cu, Fe, Ni, Mn, Zn with concentrations of 76.680, 26.130, 0.113, 11.490, 1.020 mg/dm3, respectively. The cascade line reactor is equipped with the following components: for feeding of effluents, for injection of the precipitation agent, for pH measurements and control, and for removal of the process gases. The precipitation agent was 1M NaOH. In each of the three reactors, a changing of pH and temperature was observed. In order to verify. efficiency of heavy metals removal, chemical analyses of samples taken at different pH was done using AES-ICP. Consumption of NaOH in reactors was 370 cm3, 40 cm3 and 80 cm3, respectively. Total time of the experiment was 4 h including feeding of the first reactor. The time necessary to achieve the defined pH value was 25 min for the first reactor and 13 min for both second and third reactors. Taking into account the complete process in the cascade line

Spray coating of self-aligning passivation layer for metal grid lines

NARCIS (Netherlands)

Vuorinen, T.; Janka, M.; Rubingh, J.E.J.M.; Tuukkanen, S.; Groen, P.; Lupo, D.

2014-01-01

In applications such as organic light emitting diodes (OLEDs) or photovoltaic cells a homogenous voltage distribution in the large anode layer needs to be ensured by including a metal grid with a transparent conductor layer. To ensure sufficient conductivity, relatively thick metal lines are used,

Oxygen abundance in metal-poor dwarfs, derived from the forbidden line

Science.gov (United States)

Spite, M.; Spite, F.

1991-12-01

The oxygen abundance is redetermined in a few metal-poor dwarfs, using the oxygen forbidden line at 630 nm rather than the oxygen triplet at 777 nm previously used by Abia and Rebolo (1989). The ratios form O/Fe are clearly lower than the previous ones and are in agreement with the ratios found in the metal-poor red giants, suggesting that no real difference exists between dwarfs and giants. Finally, it can be argued that, pending the acquisition of additional information, the oxygen abundances derived from the forbidden line are more reliable than the abundances found from the triplet.

Many-body calculation of the coincidence L3 photoelectron spectroscopy main line of Ni metal

International Nuclear Information System (INIS)

Ohno, Masahide

2008-01-01

The partial singles L 3 photoelectron spectroscopy (PES) main line of Ni metal correlated with Auger electrons emitted by the localized L 3 -VV Auger decay is calculated by a many-body theory. The partial singles L 3 PES main line of Ni metal almost coincides in both line shape and peak kinetic energy (KE) with the singles one. The former main line peak shows a KE shift of only 0.01 eV toward the lower KE and a very small asymmetric line shape change compared to the singles one. The asymmetric line shape change and the peak KE shift of the partial singles L 3 main line are very small. However, they are due to the variation with photoelectron KE in the branching ratio of the partial Auger decay width in the partial singles L 3 PES main line by the photoelectron KE dependent imaginary part of the shakeup self-energy. The L 3 PES main line of Ni metal measured in coincidence with the L 3 -VV ( 1 G) Auger electron spectroscopy (AES) main line peak is the partial singles one modulated by a spectral function R a of a fixed energy Auger electron analyzer so that it should show only a symmetric line narrowing by R a compared to the singles one. The L 3 PES main line peak of Ni metal measured in coincidence with the delocalized band-like L 3 -VV AES peak or not completely split-off (or not completely localized) L 3 -VV ( 3 F) AES peak, will show an asymmetric line narrowing and a KE shift compared to the singles one. Thus, the L 3 PES main line of Ni metal in coincidence with various parts of the L 3 -VV AES spectrum depends on which part of the L 3 -VV AES spectrum a fixed energy Auger electron analyzer is set. The experimental verification is in need

[Comparative study of microleakage by using different finished lines in selective laser melting metal crowns].

Science.gov (United States)

Peng, Yan; Zhong, Qun; Wu, Xue-Ying; Weng, Jia-Wei

2016-12-01

To evaluate microleakage of SLM Co -Cr alloy metal crown with two types finished line (chamfer and shoulder), compared with conventional fabrication of Co -Cr alloy metal crowns. Thirty healthy non-carious human molars were selected and randomly assigned to 3 groups, 10 in each. Teeth in group A and C received a chamfer finish line preparation, whereas teeth in group C received a shoulder finish line. Conventional Co -Cr alloy metal crowns were fabricated for group A when SLM metal crowns were made for group B and group C. Glass ionomer was applied for bonding. After 5000 thermocycles ranging from 5degrees centigrade to 55degrees centigrade,all the specimens were evaluated by dye penetration and then microleakage was examined under light microscope. The data were analyzed statistically with SPSS 20.0 software package. Microleakage in group A was significantly higher than the other two groups, group B and group C showed no significant difference in microleakage while microleakage in group B was higher than that in group C. Microleakage of SLM metal crowns was significantly less than that of conventional Co-Cr alloy metal crowns; chamfer finish line designs was recommended for SLM metal crowns in consideration of reducing microleakage and protecting tooth.

Nonlinear Color–Metallicity Relations of Globular Clusters. VII. Nonlinear Absorption-line Index versus Metallicity Relations and Bimodal Index Distributions of NGC 5128 Globular Clusters

Energy Technology Data Exchange (ETDEWEB)

Kim, Sooyoung; Yoon, Suk-Jin, E-mail: sjyoon0691@yonsei.ac.kr [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of)

2017-07-01

Spectroscopy on the globular cluster (GC) system of NGC 5128 revealed bimodality in absorption-line index distributions of its old GCs. GC division is a widely observed and studied phenomenon whose interpretation has depicted host galaxy formation and evolution such that it harbors two distinct metallicity groups. Such a conventional view of GC bimodality has mainly been based on photometry. The recent GC photometric data, however, presented an alternative perspective in which the nonlinear metallicity-to-color transformation is responsible for color bimodality of GC systems. Here we apply the same line of analysis to the spectral indices and examine the absorption-line index versus metallicity relations for the NGC 5128 GC system. NGC 5128 GCs display nonlinearity in the metallicity-index planes, most prominently for the Balmer lines and by a non-negligible degree for the metallicity-sensitive magnesium line. We demonstrate that the observed spectroscopic division of NGC 5128 GCs can be caused by the nonlinear nature of the metallicity-to-index conversions and thus one does not need to resort to two separate GC subgroups. Our analysis incorporating this nonlinearity provides a new perspective on the structure of NGC 5128's GC system, and a further piece to the global picture of the formation of GC systems and their host galaxies.

Optogalvanic spectroscopy of the hyperfine structure of weak La I lines: discovery of new even parity fine structure levels

International Nuclear Information System (INIS)

Siddiqui, Imran; Khan, Shamim; Gamper, B; Windholz, L; Dembczyński, J

2013-01-01

The hyperfine structure of weak La I lines was experimentally investigated using laser optogalvanic spectroscopy in a hollow cathode discharge lamp. More than 100 La I lines were investigated and 40 new energy levels were discovered, most of them having even parity. The magnetic hyperfine interaction constants A and in some cases the electric quadrupole interaction constants B for these levels were determined. All the newly discovered levels were confirmed either by additional laser excitations (from other known levels) or by lines in a Fourier transform spectrum which could now be classified. (paper)

Optical response of a quantum dot-metal nanoparticle hybrid interacting with a weak probe field.

Science.gov (United States)

Kosionis, Spyridon G; Terzis, Andreas F; Sadeghi, Seyed M; Paspalakis, Emmanuel

2013-01-30

We study optical effects in a hybrid system composed of a semiconductor quantum dot and a spherical metal nanoparticle that interacts with a weak probe electromagnetic field. We use modified nonlinear density matrix equations for the description of the optical properties of the system and obtain a closed-form expression for the linear susceptibilities of the quantum dot, the metal nanoparticle, and the total system. We then investigate the dependence of the susceptibility on the interparticle distance as well as on the material parameters of the hybrid system. We find that the susceptibility of the quantum dot exhibits optical transparency for specific frequencies. In addition, we show that there is a range of frequencies of the applied field for which the susceptibility of the semiconductor quantum dot leads to gain. This suggests that in such a hybrid system quantum coherence can reverse the course of energy transfer, allowing flow of energy from the metallic nanoparticle to the quantum dot. We also explore the susceptibility of the metal nanoparticle and show that it is strongly influenced by the presence of the quantum dot.

An alternative to conventional babbitt metal-lined generator pads

Energy Technology Data Exchange (ETDEWEB)

Puuska, H. [Imatra Hydroelectric Power Plant (Finland)

1996-08-01

The generator refurbishment of the Imatra Hydroelectric Power Plant Unit 1 in Finland is described. The generator work called for installation of a new cooling system for the generator thrust bearing. The considerations leading to the decision to replace the conventional babbitt metal-lined pads with elastic metal-plastic coated thrust bearing pads and the installation of the new pads are outlined in the article. Results of the trial run are summarized; the end temperature of the unit was more than 20C lower than for units equipped with conventional babbitted bearings.

Biased resistor network model for electromigration failure and related phenomena in metallic lines

Science.gov (United States)

Pennetta, C.; Alfinito, E.; Reggiani, L.; Fantini, F.; Demunari, I.; Scorzoni, A.

2004-11-01

Electromigration phenomena in metallic lines are studied by using a biased resistor network model. The void formation induced by the electron wind is simulated by a stochastic process of resistor breaking, while the growth of mechanical stress inside the line is described by an antagonist process of recovery of the broken resistors. The model accounts for the existence of temperature gradients due to current crowding and Joule heating. Alloying effects are also accounted for. Monte Carlo simulations allow the study within a unified theoretical framework of a variety of relevant features related to the electromigration. The predictions of the model are in excellent agreement with the experiments and in particular with the degradation towards electrical breakdown of stressed Al-Cu thin metallic lines. Detailed investigations refer to the damage pattern, the distribution of the times to failure (TTFs), the generalized Black’s law, the time evolution of the resistance, including the early-stage change due to alloying effects and the electromigration saturation appearing at low current densities or for short line lengths. The dependence of the TTFs on the length and width of the metallic line is also well reproduced. Finally, the model successfully describes the resistance noise properties under steady state conditions.

Non-LTE line-blanketed model atmospheres of hot stars. 2: Hot, metal-rich white dwarfs

Science.gov (United States)

Lanz, T.; Hubeny, I.

1995-01-01

We present several model atmospheres for a typical hot metal-rich DA white dwarf, T(sub eff) = 60,000 K, log g = 7.5. We consider pure hydrogen models, as well as models with various abundances of two typical 'trace' elements-carbon and iron. We calculte a number of Local Thermodynamic Equilibrium (LTE) and non-LTE models, taking into account the effect of numerous lines of these elements on the atmospheric structure. We demostrate that while the non-LTE effects are notvery significant for pure hydrogen models, except for describing correctly the central emission in H-alpha they are essential for predicting correctly the ionization balance of metals, such as carbon and iron. Previously reported discrepancies in LTE abundances determinations using C III and C IV lines are easily explained by non-LTE effects. We show that if the iron abundance is larger than 10(exp -5), the iron line opacity has to be considered not only for the spectrum synthesis, but also in the model construction itself. For such metal abundances, non-LTE metal line-blanketed models are needed for detailed abundance studies of hot, metal-rich white dwarfs. We also discuss the predicted Extreme Ultraviolet (EUV) spectrum and show that it is very sensitive to metal abundances, as well as to non-LTE effects.

Three-dimensional models of metal-poor stars

International Nuclear Information System (INIS)

Collet, R

2008-01-01

I present here the main results of recent realistic, three-dimensional (3D), hydrodynamical simulations of convection at the surface of metal-poor red giant stars. I discuss the application of these convection simulations as time-dependent, 3D, hydrodynamical model atmospheres to spectral line formation calculations and abundance analyses. The impact of 3D models on derived elemental abundances is investigated by means of a differential comparison of the line strengths predicted in 3D under the assumption of local thermodynamic equilibrium (LTE) with the results of analogous line formation calculations performed with classical, 1D, hydrostatic model atmospheres. The low surface temperatures encountered in the upper photospheric layers of 3D model atmospheres of very metal-poor stars cause spectral lines of neutral metals and molecules to appear stronger in 3D than in 1D calculations. Hence, 3D elemental abundances derived from such lines are significantly lower than estimated by analyses with 1D models. In particular, differential 3D-1D LTE abundances for C, N and O derived from CH, NH and OH lines are found to be in the range -0.5 to - 1 dex. Large negative differential 3D-1D corrections to the Fe abundance are also computed for weak low-excitation Fe i lines. The application of metal-poor 3D models to the spectroscopic analysis of extremely iron-poor halo stars is discussed.

Conductivity of Weakly Disordered Metals Close to a "Ferromagnetic" Quantum Critical Point

Science.gov (United States)

Kastrinakis, George

2018-05-01

We calculate analytically the conductivity of weakly disordered metals close to a "ferromagnetic" quantum critical point in the low-temperature regime. Ferromagnetic in the sense that the effective carrier potential V(q,ω ), due to critical fluctuations, is peaked at zero momentum q=0. Vertex corrections, due to both critical fluctuations and impurity scattering, are explicitly considered. We find that only the vertex corrections due to impurity scattering, combined with the self-energy, generate appreciable effects as a function of the temperature T and the control parameter a, which measures the proximity to the critical point. Our results are consistent with resistivity experiments in several materials displaying typical Fermi liquid behaviour, but with a diverging prefactor of the T^2 term for small a.

Nustar Reveals an Intrinsically X-ray Weak Broad Absorption Line Quasar in the Ultraluminous Infrared Galaxy Markarian 231

Science.gov (United States)

Teng, Stacy H.; Brandt. W. N.; Harrison, F. A.; Luo, B.; Alexander, D. M.; Bauer, F. E.; Boggs, S. E.; Christensen, F. E.; Comastri, A.; Craig, W. W.;

Off-line testing of multifunctional surfaces for metal forming applications

DEFF Research Database (Denmark)

Godi, A.; Grønbæk, J.; De Chiffre, L.

2015-01-01

In this paper, Bending-Under-Tension, an off-line test method simulating deep-drawing, is chosen for investigating the effectiveness of multifunctional (MUFU) surfaces in metal forming operations. Four different MUFU surfaces, characterized by a plateau bearing area and grooves for lubricant...... retention, are manufactured, together with two polished references. During the tests, surface texture is the only variable. The results show how MUFU surfaces perform better than the polished references, which produce severe galling, while MUFU surfaces with low bearing area display no clear evidence...... of galling. Metal-to-metal contact occurs anyway, but the strip material is pulverized and deposited onto the tool instead of cold-welding to it. The pockets create a discontinuity on the texture hindering pick-up propagation....

On the instability of a 3-dimensional attachment line boundary layer: Weakly nonlinear theory and a numerical approach

Science.gov (United States)

Hall, P.; Malik, M. R.

1984-01-01

The instability of a three dimensional attachment line boundary layer is considered in the nonlinear regime. Using weakly nonlinear theory, it is found that, apart from a small interval near the (linear) critical Reynolds number, finite amplitude solutions bifurcate subcritically from the upper branch of the neutral curve. The time dependent Navier-Stokes equations for the attachment line flow have been solved using a Fourier-Chebyshev spectral method and the subcritical instability is found at wavenumbers that correspond to the upper branch. Both the theory and the numerical calculations show the existence of supercritical finite amplitude (equilibrium) states near the lower branch which explains why the observed flow exhibits a preference for the lower branch modes. The effect of blowing and suction on nonlinear stability of the attachment line boundary layer is also investigated.

On the instability of a three-dimensional attachment-line boundary layer - Weakly nonlinear theory and a numerical approach

Science.gov (United States)

Hall, P.; Malik, M. R.

1986-01-01

The instability of a three-dimensional attachment-line boundary layer is considered in the nonlinear regime. Using weakly nonlinear theory, it is found that, apart from a small interval near the (linear) critical Reynolds number, finite-amplitude solutions bifurcate subcritically from the upper branch of the neutral curve. The time-dependent Navier-Stokes equations for the attachment-line flow have been solved using a Fourier-Chebyshev spectral method and the subcritical instability is found at wavenumbers that correspond to the upper branch. Both the theory and the numerical calculations show the existence of supercritical finite-amplitude (equilibrium) states near the lower branch which explains why the observed flow exhibits a preference for the lower branch modes. The effect of blowing and suction on nonlinear stability of the attachment-line boundary layer is also investigated.

Genotoxicity of 11 heavy metals detected as food contaminants in two human cell lines.

Science.gov (United States)

Kopp, B; Zalko, D; Audebert, M

2018-04-01

Heavy metals, such as arsenic (As), antimony (Sb), barium (Ba), cadmium (Cd), cobalt (Co), germanium (Ge), lead (Pb), nickel (Ni), tellurium (Te), and vanadium (V) are widely distributed in the environment and in the food chain. Human exposure to heavy metals through water and food has been reported by different international agencies. Although some of these heavy metals are essential elements for human growth and development, they may also be toxic at low concentrations due to indirect mechanisms. In this study, the genotoxic and cytotoxic properties of 15 different oxidation statuses of 11 different heavy metals were investigated using high-throughput screening (γH2AX assay) in two human cell lines (HepG2 and LS-174T) representative of target organs (liver and colon) for food contaminants. Base on their lowest observed adverse effect concentration, the genotoxic potency of each heavy metal in each cell line was ranked in decreasing order, NaAsO 2  > CdCl 2  > PbCl 2 (only in LS-174T cells) > As 2 O 5  > SbCl 3  > K 2 TeO 3  > As 2 O 3 . No significant genotoxicity was observed with the other heavy metals tested. Cell viability data indicate that several heavy metals (As, Cd, Co, Ni, Sb, and Te) induce cytotoxicity at high concentrations, whereas an increase in the number of cells was observed for lead concentrations >100 µM in both cell lines tested, suggesting that lead stimulates cell growth. All these results highlight the possible human health hazards associated with the presence of heavy metals present in food. Environ. Mol. Mutagen. 59:202-210, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Cytotoxicity effects of metal oxide nanoparticles in human tumor cell lines

International Nuclear Information System (INIS)

Lozano, T; Rey, M; Gonzalez-Fernandez, Africa; Rojas, E; Moya, S; Fleddermann, J; Estrela-Lopis, I; Donath, E; Wang, B; Mao, Z; Gao, C

2011-01-01

Metallic and metal oxide nanoparticles (Nps) have a wide range of applications in various settings including household, cosmetics and chemical industries, as well as for coatings. Nevertheless, an in-depth study of the potential toxic effects of these Nps is still needed, in order to fulfill the mandatory requirement of ensuring the safety of workers, patients and the general public. In this study, Quick Cell colorimetric assays were used to evaluate the in vitro toxicity of different metal oxide Nps [Fe(II,III)O x , TiO x , ZnO and CeO 2 ] in several cell lines. The ZnO Nps were found to be highly toxic, with a lethal dose ≤100 μg/ml for all the cell lines studied. Western blot was also used to test the ability of the different Nps to activate the complement pathway. However, no activation of this cascade was observed when the Nps were added. In addition, the aggregation state and charge of the Nps in culture media was studied by dynamic light scattering (DLS) and measurement of zeta potential. Transmission Electron Microscopy was used to analyze Np uptake and localization at the cellular level.

Gravure-Offset Printed Metallization of Multi-Crystalline Silicon Solar Cells with Low Metal-Line Width for Mass Production.

Science.gov (United States)

Lee, Jonghwan; Jeong, Chaehwan

2016-05-01

The gravure offset method has been developed toward an industrially viable printing technique for electronic circuitry. In this paper, a roller type gravure offset manufacturing process was developed to fabricate fine line for using front electrode for solar cells. In order to obtain the optimum metallization printing lines, thickness of 20 μm which is narrow line is required. The main targets are the reduction of metallized area to reduce the shading loss, and a high conductivity to transport the current as loss free as possible out of the cell. However, it is well known that there is a poor contact resistance between the front Ag electrode and the n(+) emitter. Nickel plating was conducted to prevent the increase of contact resistance and the increase of fill factor (FF). The performance of n-Si/Ag (seed layer)/Ni solar cells were observed in 609 mV of open circuit voltage, 35.54 mA/cm2 of short circuit current density, 75.75% of fill factor, and 16.04% of conversion efficiency.

The Ca II resonance lines in M dwarf stars without H-alpha emission

Energy Technology Data Exchange (ETDEWEB)

Giampapa, M.S.; Cram, L.E.; Wild, W.J. (National Solar Observatory, Tucson, AZ (USA) Sydney Univ. (Australia) Arizona Univ., Tucson (USA))

1989-10-01

Spectra of the Ca II H and K lines in a sample of 31 M dwarf stars without H-alpha emission are used to calculate chromospheric K line radiative losses, F(k), and to study the joint response of Ca II K and H-alpha to chromospheric heating in dwarf M stars. It is suggested that the poor correlation found in the equivalent width - log F(K) diagram may be due either to radial segregation of the H-alpha and K line forming regions or to lateral inhomogeneities in the chromospheres. The results confirm the existence of dM stars with weak H-alpha absorption and K line emission only slightly weaker than that of the dMe stars, and show that dM stars with weak H-alpha but kinematics and metallicities representative of the young disk population belong to a class characterized by a comparatively high degree of chromospheric activity. 32 refs.

Non-LTE effects in Al I lines

Science.gov (United States)

Menzhevitski, V. S.; Shimansky, V. V.; Shimanskaya, N. N.

2012-07-01

We present the theoretical analysis of the Al I line formation in the spectra of late-type stars ignoring the assumption of local thermodynamic equilibrium (LTE). The calculations were based on the 39-level aluminum atom model for one-dimensional hydrostatic stellar atmosphere models with the parameters: T eff from 4000 to 9000 K, log g = 0.0-4.5, and metallicity [ A] = 0.0;-1.0;-2.0;-3.0;-4.0. The aluminum atom model and the method of calculations were tested by the study of line profiles in the solar spectrum. We refined the oscillator strengths and Van-der-Vaals broadening constants C 6 of the investigated transitions. We conclude that the Al I atom is in the overionization state: the 3 p level is underpopulated in the line formation region. This leads to the line weakening, as compared with the LTE results. The overionization effect becomes more pronounced with increasing temperature and decreasing metallicity. We show that the use of various atomic data (ionization cross-sections) for the low levels of Al I does not change the behavior of non-LTE deviations, whereas the value of these deviations varies essentially. For nine selected Al I lines we calculated the grids of theoretical non-LTE corrections (Δ X NLTE = log ɛ NLTE - log ɛ LTE) to the Al abundances determinedwith the LTE assumption. The non-LTE corrections are positive and significant for the stars with temperatures T eff > 6000 K. These corrections weakly depend on log g, and increase with declining stellar metallicity.

SDSS-IV MaNGA: the impact of diffuse ionized gas on emission-line ratios, interpretation of diagnostic diagrams and gas metallicity measurements

Science.gov (United States)

Zhang, Kai; Yan, Renbin; Bundy, Kevin; Bershady, Matthew; Haffner, L. Matthew; Walterbos, René; Maiolino, Roberto; Tremonti, Christy; Thomas, Daniel; Drory, Niv; Jones, Amy; Belfiore, Francesco; Sánchez, Sebastian F.; Diamond-Stanic, Aleksandar M.; Bizyaev, Dmitry; Nitschelm, Christian; Andrews, Brett; Brinkmann, Jon; Brownstein, Joel R.; Cheung, Edmond; Li, Cheng; Law, David R.; Roman Lopes, Alexandre; Oravetz, Daniel; Pan, Kaike; Storchi Bergmann, Thaisa; Simmons, Audrey

2017-04-01

Diffuse ionized gas (DIG) is prevalent in star-forming galaxies. Using a sample of 365 nearly face-on star-forming galaxies observed by Mapping Nearby Galaxies at APO, we demonstrate how DIG in star-forming galaxies impacts the measurements of emission-line ratios, hence the interpretation of diagnostic diagrams and gas-phase metallicity measurements. At fixed metallicity, DIG-dominated low ΣHα regions display enhanced [S II]/Hα, [N II]/Hα, [O II]/Hβ and [O I]/Hα. The gradients in these line ratios are determined by metallicity gradients and ΣHα. In line ratio diagnostic diagrams, contamination by DIG moves H II regions towards composite or low-ionization nuclear emission-line region (LI(N)ER)-like regions. A harder ionizing spectrum is needed to explain DIG line ratios. Leaky H II region models can only shift line ratios slightly relative to H II region models, and thus fail to explain the composite/LI(N)ER line ratios displayed by DIG. Our result favours ionization by evolved stars as a major ionization source for DIG with LI(N)ER-like emission. DIG can significantly bias the measurement of gas metallicity and metallicity gradients derived using strong-line methods. Metallicities derived using N2O2 are optimal because they exhibit the smallest bias and error. Using O3N2, R23, N2 = [N II]/Hα and N2S2Hα to derive metallicities introduces bias in the derived metallicity gradients as large as the gradient itself. The strong-line method of Blanc et al. (IZI hereafter) cannot be applied to DIG to get an accurate metallicity because it currently contains only H II region models that fail to describe the DIG.

Off-Line Testing of Tribo-Systems for Sheet Metal Forming Production

DEFF Research Database (Denmark)

Bay, Niels; Ceron, Ermanno

2014-01-01

Off-line testing of new tribo-systems for sheet metal forming production is an important issue, when new, environmentally benign lubricants are to be introduced. To obtain useful results it is, however, vital to ensure similar conditions as in the production process regarding the main tribo...... leading to very high tool/workpiece interface pressure and temperature in the second re-draw. Under such conditions only the best lubricant systems work satisfactory, and the paper shows how the performance of different tribo-systems in production may be predicted by off-line testing combined...

Propagation properties of dielectric-lined hollow cylindrical metallic waveguides for THz waves

International Nuclear Information System (INIS)

Huang Binke; Zhao Chongfeng

2013-01-01

For the rigorous analysis of the propagation properties of dielectric-lined hollow cylindrical metallic waveguides operating in the THz range of frequencies, the characteristic equation for propagation constants is derived from the electromagnetic field equations and the boundary conditions of the dielectric-lined waveguides. The propagation constant of the dominant hybrid HE 11 mode can be obtained by solving the characteristic equation with the improved Muller method. The classical relaxation-effect model for the conductivity is adopted to describe the frequency dispersive behavior of normal metals for the metallic waveguide wall. For a 1.8 mm bore diameter silver waveguide with the inner surface coated with a 17 μm-thick layer of polystyrene(PS) film, the transmission losses of HE 11 mode can be reduced to the level below 1 dB/m at 1.5-3.0 THz, and the dispersion is relatively small for HE 11 mode. In addition, with the PS film thickness increasing, the transmission losses of HE 11 mode increase first and then decrease for a 2.2 mm bore diameter silver waveguide at 2.5 THz, and the minimum loss can be achieved by adopting the optimum dielectric layer thickness. (authors)

Possibility for using of two Paulownia lines as a tool for remediation of heavy metal contaminated soil.

Science.gov (United States)

Tzvetkova, Nikolina; Miladinova, Kamelya; Ivanova, Katya; Georgieva, Teodora; Geneva, Marya; Markovska, Yuliana

2015-01-01

One-year-old two Paulownia lines (Ptomentosa x fortunei--TF 01 and R elongata x fortunei--EF 02) were grown, as pot experiment, in soil collected from the field of waste depository of Kremikovtzi ferrous metallurgical industry near Sofia. The soil was heavily polluted with Cd. Metals content (Ca, Mg, K, Na, Cd, Cu, Pb, Zn and Fe) in soil and its distribution in roots, stems and leaves of both lines was studied. The results showed that Ca and K accumulated more in stem, Mg, Na, Fe and Cd in root, while Pb, Cu and Zn in the leaves of both lines. The bloaccumulation factor (BF) and translocation factor (TF) were evaluated in order to determine the potential of plants in removing metals from contaminated soil. The BF for Fe, Pb, Cu and Zn in TF 01 line exceeded that of EF 02 line--5.6; 1.03; 1.20; 1.14 times, respectively. TF was higher in TF 01 line for Fe, Pb and Cd (6.0; 1.92 and 1.03, respectively), but not for Cu and Zn. The success of phytoremediation depends on plant growth and restricted distribution of heavy metals in shoots. Our results showed that stem length and total leaf area of Paulownia elongata x fortunei were higher than Paulownia tomentosa x fortuneibut BF for Cu and Zn and TF for Pb was less. BF for Cd was 1.7 times higher and TF for Zn was 1.03 times higher in Paulownia elongata x fortunei. Selected two lines (P. tomentosa x fortunei--TF 01 and P elongataxfortunei--EF02) were accumulators of Cu, Zn and Cd. Paulownia tomentosax fortunei accumulated more Pb and Zn in aboveground parts, while Paulownia elongata x fortunei--accumulated Zn only. These lines proved to be a promising species for phytoremediation of heavy metal polluted soils due to high biomass productivity.

On image tube spectrophotometry of weak emission lines

International Nuclear Information System (INIS)

Duflot, R.

1979-01-01

The usual precision of image tube spectrophotometry measures relative to low intensity lines can be improved by the 'method of two lines'. This operating process tested on H II galactic regions leads to a precision of 13%. (Auth.)

Los resonance lines in promethiumlike heavy ions

International Nuclear Information System (INIS)

Nakamura, Nobuyuki; Kobayashi, Yusuke; Kato, Daiji; Sakaue, Hiroyuki A.; Murakami, Izumi

2016-01-01

Identifying the ns - np resonance lines in alkali-metal-like ions is an important issue in fusion plasma science in the view of spectroscopic diagnostics and radiation power loss. Whereas for n=2, 3 and 4 these resonances are prominent and well studied, so far no one could clearly identify the resonance lines for n=5 in the promethiumlike sequence. We have now experimentally clarified the reason for the 'lost resonance lines. In the present study, highly-charged bismuth ions have been studied using a compact electron beam ion trap (EBIT). Extreme ultraviolet emission from the bismuth ions produced and trapped in the EBIT is observed with a grazing-incidence flat-field spectrometer. The energy dependent spectra are compared with a collisional-radiative model calculation, and we show that the 5s - 5p resonance lines are very weak in plasma with a wide range of electron density due to the presence of a long-lived metastable state. (author)

Electromagnetic interference produced by power or electrified railway lines on metallic pipe networks

International Nuclear Information System (INIS)

Lucca, G.

1999-01-01

The paper presents an algorithm for the calculation, in the frequency domain, of the induced voltages and currents on a generic metallic pipe network exposed to the electromagnetic interference from a power line or an electrified railway line. By assuming as known the voltages and the currents on the inducing line, the algorithm may be subdivided into the following main steps: a) determination of the ideal electromotive force and current generators to be applied to the induced structure in order to represent the electromagnetic influence from the inducing line; b) modelling of the pipe network by means of a suitable equivalent electric network; c) calculation of voltages and currents on the induced network [it

New method for metal-abundance determination in late-type stars

International Nuclear Information System (INIS)

Campbell, B.

1978-01-01

An empirical technique has been developed for deriving heavy-element abundances from near-infrared blends of weak metallic lines. It is applicable to G and K stars of population I and II and is independent of gravity and microturbulence. A feature of the method is that it gives abundances for ''super-metal-rich'' giants consistent with high-dispersion analyses. The technique may be applicable to abundance problems in galaxies. It is also shown that precision colorimetry unaffected by sky transparency changes is possible with a diode array spectrometer

Steep Hard-X-ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-Line Quasars

Science.gov (United States)

Marlar, Andrea; Shemmer, Ohad; Anderson, Scott F.; Brandt, W. Niel; Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Luo, Bin; Plotkin, Richard; Richards, Gordon T.; Schneider, Donald P.; Wu, Jianfeng

2018-06-01

We present XMM-Newton imaging spectroscopy of ten weak emission-line quasars (WLQs) at 0.928 ≤ z ≤ 3.767, six of which are radio quiet and four which are radio intermediate. The new X-ray data enabled us to measure the hard-X-ray power-law photon index (Γ) in each source with relatively high accuracy. These measurements allowed us to confirm previous reports that WLQs have steeper X-ray spectra, therefore indicating higher accretion rates with respect to "typical" quasars. A comparison between the Γ values of our radio-quiet WLQs and those of a carefully-selected, uniform sample of 84 quasars shows that the first are significantly higher, at the ≥ 3σ level. Collectively, the four radio-intermediate WLQs have lower Γ values with respect to the six radio-quiet WLQs, as may be expected if the spectra of the first group are contaminated by X-ray emission from a jet. These results suggest that, in the absence of significant jet emission along our line of sight, WLQs constitute the extreme high end of the accretion rate distribution in quasars. We detect soft excess emission in our lowest-redshift radio-quiet WLQ, in agreement with previous findings suggesting that the prominence of this feature is associated with a high accretion rate. We have not detected signatures of Compton reflection, Fe Kα lines, or strong variability between two X-ray epochs in any of our WLQs.

SN 2010ay IS A LUMINOUS AND BROAD-LINED TYPE Ic SUPERNOVA WITHIN A LOW-METALLICITY HOST GALAXY

Energy Technology Data Exchange (ETDEWEB)

Sanders, N. E.; Soderberg, A. M.; Foley, R. J.; Chornock, R.; Chomiuk, L.; Berger, E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Valenti, S.; Smartt, S.; Botticella, M. T. [Astrophysics Research Centre, School of Maths and Physics, Queen' s University, Belfast BT7 1NN (United Kingdom); Hurley, K. [Space Sciences Laboratory, University of California Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Barthelmy, S. D.; Gehrels, N.; Cline, T. [NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771 (United States); Levesque, E. M. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Narayan, G. [Department of Physics, Harvard University, Cambridge, MA 02138 (United States); Briggs, M. S.; Connaughton, V. [CSPAR, University of Alabama in Huntsville, Huntsville, AL (United States); Terada, Y. [Department of Physics, Saitama University, Shimo-Okubo, Sakura-ku, Saitama-shi, Saitama 338-8570 (Japan); Golenetskii, S.; Mazets, E., E-mail: nsanders@cfa.harvard.edu [Ioffe Physico-Technical Institute, Laboratory for Experimental Astrophysics, 26 Polytekhnicheskaya, St. Petersburg 194021 (Russian Federation); and others

2012-09-10

We report on our serendipitous pre-discovery detection and follow-up observations of the broad-lined Type Ic supernova (SN Ic) 2010ay at z = 0.067 imaged by the Pan-STARRS1 3{pi} survey just {approx}4 days after explosion. The supernova (SN) had a peak luminosity, M{sub R} Almost-Equal-To -20.2 mag, significantly more luminous than known GRB-SNe and one of the most luminous SNe Ib/c ever discovered. The absorption velocity of SN 2010ay is v{sub Si} Almost-Equal-To 19 Multiplication-Sign 10{sup 3} km s{sup -1} at {approx}40 days after explosion, 2-5 times higher than other broad-lined SNe and similar to the GRB-SN 2010bh at comparable epochs. Moreover, the velocity declines {approx}2 times slower than other SNe Ic-BL and GRB-SNe. Assuming that the optical emission is powered by radioactive decay, the peak magnitude implies the synthesis of an unusually large mass of {sup 56}Ni, M{sub Ni} = 0.9 M{sub Sun }. Applying scaling relations to the light curve, we estimate a total ejecta mass, M{sub ej} Almost-Equal-To 4.7 M{sub Sun }, and total kinetic energy, E{sub K} Almost-Equal-To 11 Multiplication-Sign 10{sup 51} erg. The ratio of M{sub Ni} to M{sub ej} is {approx}2 times as large for SN 2010ay as typical GRB-SNe and may suggest an additional energy reservoir. The metallicity (log (O/H){sub PP04} + 12 = 8.19) of the explosion site within the host galaxy places SN 2010ay in the low-metallicity regime populated by GRB-SNe, and {approx}0.5(0.2) dex lower than that typically measured for the host environments of normal (broad-lined) SNe Ic. We constrain any gamma-ray emission with E{sub {gamma}} {approx}< 6 Multiplication-Sign 10{sup 48} erg (25-150 keV), and our deep radio follow-up observations with the Expanded Very Large Array rule out relativistic ejecta with energy E {approx}> 10{sup 48} erg. We therefore rule out the association of a relativistic outflow like those that accompanied SN 1998bw and traditional long-duration gamma-ray bursts (GRBs), but we place less

Stellar Absorption Line Analysis of Local Star-forming Galaxies: The Relation between Stellar Mass, Metallicity, Dust Attenuation, and Star Formation Rate

Energy Technology Data Exchange (ETDEWEB)

Jabran Zahid, H. [Smithsonian Astrophysical Observatory, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kudritzki, Rolf-Peter; Ho, I-Ting [University of Hawaii at Manoa, Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Conroy, Charlie [Department of Astronomy, Harvard University, Cambridge, MA, 02138 (United States); Andrews, Brett, E-mail: zahid@cfa.harvard.edu [PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, 3941 O’Hara Street, Pittsburgh, PA 15260 (United States)

2017-09-20

We analyze the optical continuum of star-forming galaxies in the Sloan Digital Sky Survey by fitting stacked spectra with stellar population synthesis models to investigate the relation between stellar mass, stellar metallicity, dust attenuation, and star formation rate. We fit models calculated with star formation and chemical evolution histories that are derived empirically from multi-epoch observations of the stellar mass–star formation rate and the stellar mass–gas-phase metallicity relations, respectively. We also fit linear combinations of single-burst models with a range of metallicities and ages. Star formation and chemical evolution histories are unconstrained for these models. The stellar mass–stellar metallicity relations obtained from the two methods agree with the relation measured from individual supergiant stars in nearby galaxies. These relations are also consistent with the relation obtained from emission-line analysis of gas-phase metallicity after accounting for systematic offsets in the gas-phase metallicity. We measure dust attenuation of the stellar continuum and show that its dependence on stellar mass and star formation rate is consistent with previously reported results derived from nebular emission lines. However, stellar continuum attenuation is smaller than nebular emission line attenuation. The continuum-to-nebular attenuation ratio depends on stellar mass and is smaller in more massive galaxies. Our consistent analysis of stellar continuum and nebular emission lines paves the way for a comprehensive investigation of stellar metallicities of star-forming and quiescent galaxies.

Stellar Absorption Line Analysis of Local Star-forming Galaxies: The Relation between Stellar Mass, Metallicity, Dust Attenuation, and Star Formation Rate

International Nuclear Information System (INIS)

Jabran Zahid, H.; Kudritzki, Rolf-Peter; Ho, I-Ting; Conroy, Charlie; Andrews, Brett

2017-01-01

We analyze the optical continuum of star-forming galaxies in the Sloan Digital Sky Survey by fitting stacked spectra with stellar population synthesis models to investigate the relation between stellar mass, stellar metallicity, dust attenuation, and star formation rate. We fit models calculated with star formation and chemical evolution histories that are derived empirically from multi-epoch observations of the stellar mass–star formation rate and the stellar mass–gas-phase metallicity relations, respectively. We also fit linear combinations of single-burst models with a range of metallicities and ages. Star formation and chemical evolution histories are unconstrained for these models. The stellar mass–stellar metallicity relations obtained from the two methods agree with the relation measured from individual supergiant stars in nearby galaxies. These relations are also consistent with the relation obtained from emission-line analysis of gas-phase metallicity after accounting for systematic offsets in the gas-phase metallicity. We measure dust attenuation of the stellar continuum and show that its dependence on stellar mass and star formation rate is consistent with previously reported results derived from nebular emission lines. However, stellar continuum attenuation is smaller than nebular emission line attenuation. The continuum-to-nebular attenuation ratio depends on stellar mass and is smaller in more massive galaxies. Our consistent analysis of stellar continuum and nebular emission lines paves the way for a comprehensive investigation of stellar metallicities of star-forming and quiescent galaxies.

Thin layer activation : on-line monitoring of metal loss in process plant

International Nuclear Information System (INIS)

Boulton, L.H.; Wallace, G.

1993-01-01

Corrosion, erosion and wear of metals is a common cause of failure in some process plant and equipment. Monitoring of these destructive effects has been done for many years to help plant engineers minimise the damage, in order to avoid unexpected failures and unscheduled shutdowns. Traditional methods of monitoring, such as standard NDT techniques, inform the engineer of what has happened, providing data such as culmulative loss of wall thickness. The modern approach to monitoring however, is to employ a technique which gives both current loss rates as well as integrated losses. Thin Layer Activation (TLA) provides on-line monitoring of corrosion, erosion and wear of metals, to a high degree of accuracy. It also gives cumulative information which can be backed up with weight-loss results if required. Thus current rather than historical loss rates are measured before any significant loss of metal has occurred. (author). 14 refs., 2 figs

A field study on heavy metals phytoattenuation potential of monocropping and intercropping of maize and/or legumes in weakly alkaline soils.

Science.gov (United States)

Zhu, Saiyong; Ma, Xinwang; Guo, Rui; Ai, Shiwei; Liu, Bailin; Zhang, Wenya; Zhang, Yingmei

2016-10-02

The study focused on the phytoattenuation effects of monocropping and intercropping of maize (Zea mays) and/or legumes on Cu, Zn, Pb, and Cd in weakly alkaline soils. Nine growth stages of monocropping maize were chosen to study the dynamic process of extraction of heavy metals. The total content of heavy metals extracted by the aerial part of monocropped maize increased in a sigmoidal pattern over the effective accumulative temperature. The biggest biomass, highest extraction content, and lowest heavy metals bioaccumulation level occurred at physiological maturity. Among the different planting patterns, including monocropping and intercropping of maize and/or soybean (Glycine max), pea (Pisum sativum), and alfalfa (Medicago sativa), the extraction efficiency of Cu, Zn, Pb, and Cd varied greatly. Only intercropping of maize and soybean yielded relatively higher extraction efficiency for the four metals with no significant difference in the total biomass. Moreover, the heavy metals concentrations in dry biomass from all the planting patterns in the present study were within China's national legal thresholds for fodder use. Therefore, slightly polluted alkaline soils can be safely used through monocropping and intercropping of maize and/or legumes for a range of purposes. In particular, this study indicated that intercropping improves soil ecosystems polluted by heavy metals compared with monocropping.

On-line/on-site analysis of heavy metals in water and soils by laser induced breakdown spectroscopy

Science.gov (United States)

Meng, Deshuo; Zhao, Nanjing; Wang, Yuanyuan; Ma, Mingjun; Fang, Li; Gu, Yanhong; Jia, Yao; Liu, Jianguo

2017-11-01

The enrichment method of heavy metal in water with graphite and aluminum electrode was studied, and combined with plasma restraint device for improving the sensitivity of detection and reducing the limit of detection (LOD) of elements. For aluminum electrode enrichment, the LODs of Cd, Pb and Ni can be as low as several ppb. For graphite enrichment, the measurement time can be less than 3 min. The results showed that the graphite enrichment and aluminum electrode enrichment method can effectively improve the LIBS detection ability. The graphite enrichment method combined with plasma spatial confinement is more suitable for on-line monitoring of industrial waste water, the aluminum electrode enrichment method can be used for trace heavy metal detection in water. A LIBS method and device for soil heavy metals analysis was also developed, and a mobile LIBS system was tested in outfield. The measurement results deduced from LIBS and ICP-MS had a good consistency. The results provided an important application support for rapid and on-site monitoring of heavy metals in soil. (Left: the mobile LIBS system for analysis of heavy metals in soils. Top right: the spatial confinement device. Bottom right: automatic graphite enrichment device for on0line analysis of heavy metals in water).

A POPULATION OF X-RAY WEAK QUASARS: PHL 1811 ANALOGS AT HIGH REDSHIFT

International Nuclear Information System (INIS)

Wu Jianfeng; Brandt, W. N.; Schneider, Donald P.; Hall, Patrick B.; Gibson, Robert R.; Schmidt, Sarah J.; Richards, Gordon T.; Shemmer, Ohad; Just, Dennis W.

2011-01-01

We report the results from Chandra and XMM-Newton observations of a sample of 10 type 1 quasars selected to have unusual UV emission-line properties (weak and blueshifted high-ionization lines; strong UV Fe emission) similar to those of PHL 1811, a confirmed intrinsically X-ray weak quasar. These quasars were identified by the Sloan Digital Sky Survey at high redshift (z ∼ 2.2); eight are radio quiet while two are radio intermediate. All of the radio-quiet PHL 1811 analogs, without exception, are notably X-ray weak by a mean factor of ∼13. These sources lack broad absorption lines and have blue UV/optical continua, supporting the hypothesis that they are intrinsically X-ray weak like PHL 1811 itself. However, their average X-ray spectrum appears to be harder than those of typical quasars, which may indicate the presence of heavy intrinsic X-ray absorption. Our sample of radio-quiet PHL 1811 analogs supports a connection between an X-ray weak spectral energy distribution and PHL 1811-like UV emission lines; this connection provides an economical way to identify X-ray weak type 1 quasars. The fraction of radio-quiet PHL 1811 analogs in the radio-quiet quasar population is estimated to be ∼< 1.2%. We have investigated correlations between relative X-ray brightness and UV emission-line properties (e.g., C IV equivalent width and blueshift) for a sample combining our radio-quiet PHL 1811 analogs, PHL 1811 itself, and typical type 1 quasars. These correlation analyses suggest that PHL 1811 analogs may have extreme wind-dominated broad emission-line regions. Observationally, the radio-quiet PHL 1811 analogs appear to be a subset (∼30%) of radio-quiet weak-line quasars (WLQs). The existence of a subset of quasars in which high-ionization 'shielding gas' covers most of the broad emission-line region (BELR), but little more than the BELR, could potentially unify the PHL 1811 analogs and WLQs. The two radio-intermediate PHL 1811 analogs are X-ray bright. X

Application of a chronoamperometric measurement to the on-line monitoring of a lithium metal reduction for uranium oxide

International Nuclear Information System (INIS)

Kim, Tack-Jin; Cho, Young-Hwan; Choi, In-Kyu; Kang, Jun-Gill; Song, Kyuseok; Jee, Kwang-Yong

2008-01-01

Both a potentiometric and a chronoamperometric electrochemical technique have been applied in an attempt to develop an efficient method for an on-line monitoring of a lithium metal reduction process of uranium oxides at a high-temperature in a molten salt medium. As a result of this study, it was concluded that the chronoamperometric method provided a simple and effective way for a direct on-line monitoring measurement of a lithium metal reduction process of uranium oxides at 650 o C by the measuring electrical currents dependency on a variation of the reduction time for the reaction. A potentiometric method, by adopting a homemade oxide ion selective electrode made of ZrO 2 stabilized by a Y 2 O 3 doping, however, was found to be inappropriate for an on-line monitoring of the reduction reaction of uranium oxide in the presence of lithium metal due to an abnormal behavior of the adopted electrodes. The observed experimental results were discussed in detail by comparing them with previously published experimental data

Metal-Poor, Strongly Star-Forming Galaxies in the DEEP2 Survey: The Relationship Between Stellar Mass, Temperature-Based Metallicity, and Star Formation Rate

Science.gov (United States)

Ly, Chun; Rigby, Jane R.; Cooper, Michael; Yan, Renbin

2015-01-01

We report on the discovery of 28 redshift (z) approximately equal to 0.8 metal-poor galaxies in DEEP2. These galaxies were selected for their detection of the weak [O (sub III)] lambda 4363 emission line, which provides a "direct" measure of the gas-phase metallicity. A primary goal for identifying these rare galaxies is to examine whether the fundamental metallicity relation (FMR) between stellar mass, gas metallicity, and star formation rate (SFR) holds for low stellar mass and high SFR galaxies. The FMR suggests that higher SFR galaxies have lower metallicity (at fixed stellar mass). To test this trend, we combine spectroscopic measurements of metallicity and dust-corrected SFR with stellar mass estimates from modeling the optical photometry. We find that these galaxies are 1.05 plus or minus 0.61 dex above the redshift (z) approximately 1 stellar mass-SFR relation and 0.23 plus or minus 0.23 dex below the local mass-metallicity relation. Relative to the FMR, the latter offset is reduced to 0.01 dex, but significant dispersion remains dex with 0.16 dex due to measurement uncertainties). This dispersion suggests that gas accretion, star formation, and chemical enrichment have not reached equilibrium in these galaxies. This is evident by their short stellar mass doubling timescale of approximately equal to 100 (sup plus 310) (sub minus 75) million years which suggests stochastic star formation. Combining our sample with other redshift (z) of approximately 1 metal-poor galaxies, we find a weak positive SFR-metallicity dependence (at fixed stellar mass) that is significant at 94.4 percent confidence. We interpret this positive correlation as recent star formation that has enriched the gas but has not had time to drive the metal-enriched gas out with feedback mechanisms.

Soft roll linings - better conduits: First press of the PS 2, paper machine, Belišće, Croatia

Directory of Open Access Journals (Sweden)

Dolenc Iztok

2005-01-01

Full Text Available Paper with demanding technical properties is formed in the press of the paper machine when the paper pulp is passed between the rolls. In order to form paper in the appropriate manner, an elastic lining with particular stiffness is spread over the rolls. In this study a practical example of how softer linings generally give better results concerning the percentage of the dry part and the paper structure is presented. From the rubber roll manufacturers' point of view, the weak side of soft linings lies in greater deformations, which present difficulties in obtaining good adhesion between the lining and metal core of the roll. Only the best manufacturers in the industry can match such high demands.

A large sample of Kohonen-selected SDSS quasars with weak emission lines: selection effects and statistical properties

Science.gov (United States)

Meusinger, H.; Balafkan, N.

2014-08-01

Aims: A tiny fraction of the quasar population shows remarkably weak emission lines. Several hypotheses have been developed, but the weak line quasar (WLQ) phenomenon still remains puzzling. The aim of this study was to create a sizeable sample of WLQs and WLQ-like objects and to evaluate various properties of this sample. Methods: We performed a search for WLQs in the spectroscopic data from the Sloan Digital Sky Survey Data Release 7 based on Kohonen self-organising maps for nearly 105 quasar spectra. The final sample consists of 365 quasars in the redshift range z = 0.6 - 4.2 (z¯ = 1.50 ± 0.45) and includes in particular a subsample of 46 WLQs with equivalent widths WMg iiattention was paid to selection effects. Results: The WLQs have, on average, significantly higher luminosities, Eddington ratios, and accretion rates. About half of the excess comes from a selection bias, but an intrinsic excess remains probably caused primarily by higher accretion rates. The spectral energy distribution shows a bluer continuum at rest-frame wavelengths ≳1500 Å. The variability in the optical and UV is relatively low, even taking the variability-luminosity anti-correlation into account. The percentage of radio detected quasars and of core-dominant radio sources is significantly higher than for the control sample, whereas the mean radio-loudness is lower. Conclusions: The properties of our WLQ sample can be consistently understood assuming that it consists of a mix of quasars at the beginning of a stage of increased accretion activity and of beamed radio-quiet quasars. The higher luminosities and Eddington ratios in combination with a bluer spectral energy distribution can be explained by hotter continua, i.e. higher accretion rates. If quasar activity consists of subphases with different accretion rates, a change towards a higher rate is probably accompanied by an only slow development of the broad line region. The composite WLQ spectrum can be reasonably matched by the

THE MASS-METALLICITY RELATION WITH THE DIRECT METHOD ON STACKED SPECTRA OF SDSS GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Andrews, Brett H.; Martini, Paul, E-mail: andrews@astronomy.ohio-state.edu [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)

2013-03-10

The relation between galaxy stellar mass and gas-phase metallicity is a sensitive diagnostic of the main processes that drive galaxy evolution, namely cosmological gas inflow, metal production in stars, and gas outflow via galactic winds. We employed the direct method to measure the metallicities of {approx}200,000 star-forming galaxies from the Sloan Digital Sky Survey that were stacked in bins of (1) stellar mass and (2) both stellar mass and star formation rate (SFR) to significantly enhance the signal-to-noise ratio of the weak [O III] {lambda}4363 and [O II] {lambda}{lambda}7320, 7330 auroral lines required to apply the direct method. These metallicity measurements span three decades in stellar mass from log(M{sub *}/M{sub Sun }) = 7.4-10.5, which allows the direct method mass-metallicity relation to simultaneously capture the high-mass turnover and extend a full decade lower in mass than previous studies that employed more uncertain strong line methods. The direct method mass-metallicity relation rises steeply at low mass (O/H {proportional_to} M{sub *} {sup 1/2}) until it turns over at log(M{sub *}/M{sub Sun }) = 8.9 and asymptotes to 12 + log(O/H) = 8.8 at high mass. The direct method mass-metallicity relation has a steeper slope, a lower turnover mass, and a factor of two to three greater dependence on SFR than strong line mass-metallicity relations. Furthermore, the SFR-dependence appears monotonic with stellar mass, unlike strong line mass-metallicity relations. We also measure the N/O abundance ratio, an important tracer of star formation history, and find the clear signature of primary and secondary nitrogen enrichment. N/O correlates tightly with oxygen abundance, and even more so with stellar mass.

Conductivity of weakly disordered strange metals: From conformal to hyperscaling-violating regimes

Directory of Open Access Journals (Sweden)

Andrew Lucas

2015-03-01

Full Text Available We present a semi-analytic method for constructing holographic black holes that interpolate from anti-de Sitter space to hyperscaling-violating geometries. These are holographic duals of conformal field theories in the presence of an applied chemical potential, μ, at a non-zero temperature, T, and allow us to describe the crossover from ‘strange metal’ physics at T≪μ, to conformal physics at T≫μ. Our holographic technique adds an extra gauge field and exploits structure of the Einstein–Maxwell system to manifestly find 1-parameter families of solutions of the Einstein-matter system in terms of a small family of functions, obeying a nested set of differential equations. Using these interpolating geometries, we re-consider holographically some recent questions of interest about hyperscaling-violating field theories. Our focus is a more detailed holographic computation of the conductivity of strange metals, weakly perturbed by disorder coupled to scalar operators, including both the average conductivity as well as sample-to-sample fluctuations. Our findings are consistent with previous scaling arguments, though we point out logarithmic corrections in some special (holographic cases. We also discuss the nature of superconducting instabilities in hyperscaling-violating geometries with appropriate choices of scalar couplings.

Weak effect of metal type and ica genes on staphylococcal infection of titanium and stainless steel implants.

Science.gov (United States)

Hudetz, D; Ursic Hudetz, S; Harris, L G; Luginbühl, R; Friederich, N F; Landmann, R

2008-12-01

Currently, ica is considered to be the major operon responsible for staphylococcal biofilm. The effect of biofilm on susceptibility to staphylococcal infection of different implant materials in vivo is unclear. The interaction of ica-positive (wild-type (WT)) and ica-negative (ica(-)) Staphylococcus aureus and Staphylococcus epidermidis strains with titanium and both smooth and rough stainless steel surfaces was studied by scanning electron microscopy in vitro and in a mouse tissue cage model during 2 weeks following perioperative or postoperative inoculation in vivo. In vitro, WT S. epidermidis adhered equally and more strongly than did WT S. aureus to all materials. Both WT strains, but not ica(-) strains, showed multilayered biofilm. In vivo, 300 CFUs of WT and ica(-)S. aureus led, in all metal cages, to an infection with a high level of planktonic CFUs and only 0.89% adherent CFUs after 8 days. In contrast, 10(6) CFUs of the WT and ica(-) strains were required for postoperative infection with S. epidermidis. In all metal types, planktonic numbers of S. epidermidis dropped to titanium cages adherent WT bacteria survived in higher numbers than ica(-) bacteria. In conclusion, the metal played a minor role in susceptibility to and persistence of staphylococcal infection; the presence of ica genes had a strong effect on biofilm in vitro and a weak effect in vivo; and S. epidermidis was more pathogenic when introduced during implantation than after implantation.

Electronic charge rearrangement at metal/organic interfaces induced by weak van der Waals interactions

Science.gov (United States)

Ferri, Nicola; Ambrosetti, Alberto; Tkatchenko, Alexandre

2017-07-01

Electronic charge rearrangements at interfaces between organic molecules and solid surfaces play a key role in a wide range of applications in catalysis, light-emitting diodes, single-molecule junctions, molecular sensors and switches, and photovoltaics. It is common to utilize electrostatics and Pauli pushback to control the interface electronic properties, while the ubiquitous van der Waals (vdW) interactions are often considered to have a negligible direct contribution (beyond the obvious structural relaxation). Here, we apply a fully self-consistent Tkatchenko-Scheffler vdW density functional to demonstrate that the weak vdW interactions can induce sizable charge rearrangements at hybrid metal/organic systems (HMOS). The complex vdW correlation potential smears out the interfacial electronic density, thereby reducing the charge transfer in HMOS, changes the interface work functions by up to 0.2 eV, and increases the interface dipole moment by up to 0.3 Debye. Our results suggest that vdW interactions should be considered as an additional control parameter in the design of hybrid interfaces with the desired electronic properties.

Weak measurement and its experimental realisation

International Nuclear Information System (INIS)

Flack, R; Hiley, B J

2014-01-01

The relationship between the real part of the weak value of the momentum operator at a post selected position is discussed and the meaning of the experimentally determined stream-lines in the Toronto experiment of Kocsis et al is re-examined. We argue against interpreting the energy flow lines as photon trajectories. The possibility of performing an analogous experiment using atoms is proposed in order that a direct comparison can be made with the trajectories calculated by Philippidis, Dewdney and Hiley using the Bohm approach.

The nature of extreme emission line galaxies at z = 1-2: kinematics and metallicities from near-infrared spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Maseda, Michael V.; Van der Wel, Arjen; Rix, Hans-Walter; Da Cunha, Elisabete; Meidt, Sharon E. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Pacifici, Camilla [Yonsei University Observatory, Yonsei University, Seoul 120-749 (Korea, Republic of); Momcheva, Ivelina; Van Dokkum, Pieter; Nelson, Erica J. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Brammer, Gabriel B.; Ferguson, Henry C.; Koekemoer, Anton M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Franx, Marijn; Fumagalli, Mattia [Leiden Observatory, Leiden University, Leiden (Netherlands); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Förster-Schreiber, Natascha M. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Koo, David C. [UCO/Lick Observatory and Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Lundgren, Britt F. [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States); Marchesini, Danilo [Physics and Astronomy Department, Tufts University, Robinson Hall, Room 257, Medford, MA 02155 (United States); Patel, Shannon G., E-mail: maseda@mpia.de [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); and others

2014-08-10

We present near-infrared spectroscopy of a sample of 22 Extreme Emission Line Galaxies at redshifts 1.3 < z < 2.3, confirming that these are low-mass (M{sub *} = 10{sup 8}-10{sup 9} M{sub ☉}) galaxies undergoing intense starburst episodes (M{sub *}/SFR ∼ 10-100 Myr). The sample is selected by [O III] or Hα emission line flux and equivalent width using near-infrared grism spectroscopy from the 3D-HST survey. High-resolution NIR spectroscopy is obtained with LBT/LUCI and VLT/X-SHOOTER. The [O III]/Hβ line ratio is high (≳ 5) and [N II]/Hα is always significantly below unity, which suggests a low gas-phase metallicity. We are able to determine gas-phase metallicities for seven of our objects using various strong-line methods, with values in the range 0.05-0.30 Z{sub ☉} and with a median of 0.15 Z{sub ☉}; for three of these objects we detect [O III] λ4363, which allows for a direct constraint on the metallicity. The velocity dispersion, as measured from the nebular emission lines, is typically ∼50 km s{sup –1}. Combined with the observed star-forming activity, the Jeans and Toomre stability criteria imply that the gas fraction must be large (f{sub gas} ≳ 2/3), consistent with the difference between our dynamical and stellar mass estimates. The implied gas depletion timescale (several hundred Myr) is substantially longer than the inferred mass-weighted ages (∼50 Myr), which further supports the emerging picture that most stars in low-mass galaxies form in short, intense bursts of star formation.

ISM EXCITATION AND METALLICITY OF STAR-FORMING GALAXIES AT Z ≃ 3.3 FROM NEAR-IR SPECTROSCOPY

Energy Technology Data Exchange (ETDEWEB)

Onodera, M.; Carollo, C. M.; Lilly, S.; Tacchella, S. [Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093 Zürich (Switzerland); Renzini, A. [INAF-Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122, Padova (Italy); Arimoto, N. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Capak, P. [Infrared Processing and Analysis Center (IPAC), 1200 East California Boulevard, Pasadena, CA 91125 (United States); Daddi, E. [CEA, Laboratoire AIM-CNRS-Université Paris Diderot, Irfu/SAp, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Scoville, N. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Tatehora, S. [Graduate University for Advanced Studies, 2-21-1 Osawa, Mitaka, Tokyo (Japan); Zamorani, G., E-mail: monodera@phys.ethz.ch [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)

2016-05-01

We study the relationship between stellar mass, star formation rate (SFR), ionization state, and gas-phase metallicity for a sample of 41 normal star-forming galaxies at 3 ≲ z ≲ 3.7. The gas-phase oxygen abundance, ionization parameter, and electron density of ionized gas are derived from rest-frame optical strong emission lines measured on near-infrared spectra obtained with Keck/Multi-Object Spectrograph for Infra-Red Exploration. We remove the effect of these strong emission lines in the broadband fluxes to compute stellar masses via spectral energy distribution fitting, while the SFR is derived from the dust-corrected ultraviolet luminosity. The ionization parameter is weakly correlated with the specific SFR, but otherwise the ionization parameter and electron density do not correlate with other global galaxy properties such as stellar mass, SFR, and metallicity. The mass–metallicity relation (MZR) at z ≃ 3.3 shows lower metallicity by ≃0.7 dex than that at z = 0 at the same stellar mass. Our sample shows an offset by ≃0.3 dex from the locally defined mass–metallicity–SFR relation, indicating that simply extrapolating such a relation to higher redshift may predict an incorrect evolution of MZR. Furthermore, within the uncertainties we find no SFR–metallicity correlation, suggesting a less important role of SFR in controlling the metallicity at high redshift. We finally investigate the redshift evolution of the MZR by using the model by Lilly et al., finding that the observed evolution from z = 0 to z ≃ 3.3 can be accounted for by the model assuming a weak redshift evolution of the star formation efficiency.

Feedback first: the surprisingly weak effects of magnetic fields, viscosity, conduction and metal diffusion on sub-L* galaxy formation

Science.gov (United States)

Su, Kung-Yi; Hopkins, Philip F.; Hayward, Christopher C.; Faucher-Giguère, Claude-André; Kereš, Dušan; Ma, Xiangcheng; Robles, Victor H.

2017-10-01

Using high-resolution simulations with explicit treatment of stellar feedback physics based on the FIRE (Feedback In Realistic Environments) project, we study how galaxy formation and the interstellar medium (ISM) are affected by magnetic fields, anisotropic Spitzer-Braginskii conduction and viscosity, and sub-grid metal diffusion from unresolved turbulence. We consider controlled simulations of isolated (non-cosmological) galaxies but also a limited set of cosmological 'zoom-in' simulations. Although simulations have shown significant effects from these physics with weak or absent stellar feedback, the effects are much weaker than those of stellar feedback when the latter is modelled explicitly. The additional physics have no systematic effect on galactic star formation rates (SFRs). In contrast, removing stellar feedback leads to SFRs being overpredicted by factors of ˜10-100. Without feedback, neither galactic winds nor volume-filling hot-phase gas exist, and discs tend to runaway collapse to ultra-thin scaleheights with unphysically dense clumps congregating at the galactic centre. With stellar feedback, a multi-phase, turbulent medium with galactic fountains and winds is established. At currently achievable resolutions and for the investigated halo mass range 1010-1013 M⊙, the additional physics investigated here (magnetohydrodynamic, conduction, viscosity, metal diffusion) have only weak (˜10 per cent-level) effects on regulating SFR and altering the balance of phases, outflows or the energy in ISM turbulence, consistent with simple equipartition arguments. We conclude that galactic star formation and the ISM are primarily governed by a combination of turbulence, gravitational instabilities and feedback. We add the caveat that active galactic nucleus feedback is not included in the present work.

Inhibitors of Histone Deacetylases Are Weak Activators of the FMR1 Gene in Fragile X Syndrome Cell Lines

Directory of Open Access Journals (Sweden)

Alexander A. Dolskiy

2017-01-01

Full Text Available Fragile X syndrome is the most common cause of inherited intellectual disability in humans. It is a result of CGG repeat expansion in the 5′ untranslated region (5′ UTR of the FMR1 gene. This gene encodes the FMRP protein that is involved in neuronal development. Repeat expansion leads to heterochromatinization of the promoter, gene silencing, and the subsequent absence of FMRP. To date, there is no specific therapy for the syndrome. All treatments in clinic practice provide symptomatic therapy. The development of drug therapy for Fragile X syndrome treatment is connected with the search for inhibitors of enzymes that are responsible for heterochromatinization. Here, we report a weak transcriptional activity of the FMR1 gene and the absence of FMRP protein after Fragile X syndrome cell lines treatment with two FDA approved inhibitors of histone deacetylases, romidepsin and vorinostat. We demonstrate that romidepsin, an inhibitor of class I histone deacetylases, does not activate FMR1 expression in patient cell cultures, whereas vorinostat, an inhibitor of classes I and II histone deacetylases, activates a low level of FMR1 expression in some patient cell lines.

Process Development And Simulation For Cold Fabrication Of Doubly Curved Metal Plate By Using Line Array Roll Set

International Nuclear Information System (INIS)

Shim, D. S.; Jung, C. G.; Seong, D. Y.; Yang, D. Y.; Han, J. M.; Han, M. S.

2007-01-01

For effective manufacturing of a doubly curved sheet metal, a novel sheet metal forming process is proposed. The suggested process uses a Line Array Roll Set (LARS) composed of a pair of upper and lower roll assemblies in a symmetric manner. The process offers flexibility as compared with the conventional manufacturing processes, because it does not require any complex-shaped die and loss of material by blank-holding is minimized. LARS allows flexibility of the incremental forming process and adopts the principle of bending deformation, resulting in a slight deformation in thickness. Rolls composed of line array roll sets are divided into a driving roll row and two idle roll rows. The arrayed rolls in the central lines of the upper and lower roll assemblies are motor-driven so that they deform and transfer the sheet metal using friction between the rolls and the sheet metal. The remaining rolls are idle rolls, generating bending deformation with driving rolls. Furthermore, all the rolls are movable in any direction so that they are adaptable to any size or shape of the desired three-dimensional configuration. In the process, the sheet is deformed incrementally as deformation proceeds simultaneously in rolling and transverse directions step by step. Consequently, it can be applied to the fabrication of doubly curved ship hull plates by undergoing several passes. In this work, FEM simulations are carried out for verification of the proposed incremental forming system using the chosen design parameters. Based on the results of the simulation, the relationship between the roll set configuration and the curvature of a sheet metal is determined. The process information such as the forming loads and torques acting on every roll is analyzed as important data for the design and development of the manufacturing system

ζ Oph and the weak-wind problem

Science.gov (United States)

Gvaramadze, V. V.; Langer, N.; Mackey, J.

2012-11-01

Mass-loss rate, ?, is one of the key parameters affecting evolution and observational manifestations of massive stars and their impact on the ambient medium. Despite its importance, there is a factor of ˜100 discrepancy between empirical and theoretical ? of late-type O dwarfs, the so-called weak-wind problem. In this Letter, we propose a simple novel method to constrain ? of runaway massive stars through observation of their bow shocks and Strömgren spheres, which might be of decisive importance for resolving the weak-wind problem. Using this method, we found that ? of the well-known runaway O9.5 V star ζ Oph is more than an order of magnitude higher than that derived from ultraviolet (UV) line fitting and is by a factor of 6-7 lower than those based on the theoretical recipe by Vink et al. and the Hα line. The discrepancy between ? derived by our method and that based on UV lines would be even more severe if the stellar wind is clumpy. At the same time, our estimate of ? agrees with that predicted by the moving reversing layer theory by Lucy.

NEW PERSPECTIVE ON GALAXY OUTFLOWS FROM THE FIRST DETECTION OF BOTH INTRINSIC AND TRAVERSE METAL-LINE ABSORPTION

Energy Technology Data Exchange (ETDEWEB)

Kacprzak, Glenn G.; Cooke, Jeff [Swinburne University of Technology, Victoria 3122 (Australia); Martin, Crystal L.; Ho, Stephanie H. [Physics Department, University of California, Santa Barbara, CA 93106 (United States); Bouché, Nicolas; LeReun, Audrey; Schroetter, Ilane [CNRS, Institut de Recherche en Astrophysique et Planétologie (IRAP) de Toulouse, 14 Avenue E. Belin, F-31400 Toulouse (France); Churchill, Christopher W.; Klimek, Elizabeth, E-mail: gkacprzak@astro.swin.edu.au [New Mexico State University, Las Cruces, NM 88003 (United States)

2014-09-01

We present the first observation of a galaxy (z = 0.2) that exhibits metal-line absorption back-illuminated by the galaxy (down-the-barrel) and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by Mg II, are blueshifted relative to the galaxy systemic velocity. The quasar sight line, which resides almost directly along the projected minor axis of the galaxy, probes Mg I and Mg II absorption obtained from the Keck/Low Resolution Imaging Spectrometer as well as Lyα, Si II, and Si III absorption obtained from the Hubble Space Telescope/Cosmic Origins Spectrograph. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between V {sub dtb} = 45-255 km s{sup –1}. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities V {sub outflow} = 40-80 km s{sup –1} to reproduce the transverse Mg II absorption kinematics, which is consistent with the range of V {sub dtb}. The galaxy has a metallicity, derived from Hα and N II, of [O/H] = –0.21 ± 0.08, whereas the transverse absorption has [X/H] = –1.12 ± 0.02. The galaxy star formation rate is constrained between 4.6-15 M {sub ☉} yr{sup –1} while the estimated outflow rate ranges between 1.6-4.2 M {sub ☉} yr{sup –1} and yields a wind loading factor ranging between 0.1-0.9. The galaxy and gas metallicities, the galaxy-quasar sight-line geometry, and the down-the-barrel and transverse modeled outflow velocities collectively suggest that the transverse gas originates from ongoing outflowing material from the galaxy. The ∼1 dex decrease in metallicity from the base of the outflow to the outer halo suggests metal dilution of the gas by the time it reached 58 kpc.

An in vitro cytotoxic approach to assess the toxicity of heavy metals and their binary mixtures on hippocampal HT-22 cell line.

Science.gov (United States)

Karri, Venkatanaidu; Kumar, Vikas; Ramos, David; Oliveira, Eliandre; Schuhmacher, Marta

2018-01-05

Humans are exposed to a cocktail of heavy metal toxicants in the environment. Though heavy metals are deleterious, there is a paucity of information on the toxicity of mixtures. In this study, four common neurotoxicity heavy metals lead (Pb) cadmium (Cd), arsenic (As), and methylmercury (MeHg) were exposed individually and as mixtures to HT-22 cell line for 8days. The study established that low dose exposures induced toxicity to the HT-22 cell line during 8days. The results indicates potency dependent response, the toxicity of single metals on the HT-22 cells; MeHg > As > Cd > Pb. The cytotoxicity data of single metals were used to determine the mixtures interaction profile by using the dose additivity and effect additivity method. Metal mixtures showed higher toxicities compared to individual metals. Synergistic, antagonistic or additive effects of the toxicity were observed in different mixtures in low dose exposure. The interactive responses of mixtures depend on the co-exposure metal and their respective concentration. We concluded that the combined effects should be considered in the risk assessment of heavy metal co-exposure and potency. In future, comprehensive mechanistic based investigations needed for understanding the real interactive mixtures effects at molecular level. Copyright © 2017 Elsevier B.V. All rights reserved.

New Fe i Level Energies and Line Identifications from Stellar Spectra. II. Initial Results from New Ultraviolet Spectra of Metal-poor Stars

Energy Technology Data Exchange (ETDEWEB)

Peterson, Ruth C. [SETI Institute and Astrophysical Advances, 607 Marion Place, Palo Alto, CA 94301 (United States); Kurucz, Robert L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Ayres, Thomas R., E-mail: peterson@ucolick.org [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-0389 (United States)

2017-04-01

The Fe i spectrum is critical to many areas of astrophysics, yet many of the high-lying levels remain uncharacterized. To remedy this deficiency, Peterson and Kurucz identified Fe i lines in archival ultraviolet and optical spectra of metal-poor stars, whose warm temperatures favor moderate Fe i excitation. Sixty-five new levels were recovered, with 1500 detectable lines, including several bound levels in the ionization continuum of Fe i. Here, we extend the previous work by identifying 59 additional levels, with 1400 detectable lines, by incorporating new high-resolution UV spectra of warm metal-poor stars recently obtained by the Hubble Space Telescope Imaging Spectrograph. We provide gf values for these transitions, both computed as well as adjusted to fit the stellar spectra. We also expand our spectral calculations to the infrared, confirming three levels by matching high-quality spectra of the Sun and two cool stars in the H -band. The predicted gf values suggest that an additional 3700 Fe i lines should be detectable in existing solar infrared spectra. Extending the empirical line identification work to the infrared would help confirm additional Fe i levels, as would new high-resolution UV spectra of metal-poor turnoff stars below 1900 Å.

Some metal-graphite and metal-ceramic composites for use as high energy brake lining materials

Science.gov (United States)

Bill, R. C.

1974-01-01

Materials were studied as candidates for development as potential new aircraft brake lining materials. These families were (1) copper-graphite composites; (2) nickel-graphite composites; (3) copper - rare-earth-oxide (gadolinium oxide (Gd2O3) or lanthanum oxide (La2O3)) composites and copper - rare-earth-oxide (La2O3) - rare-earth-fluoride (lanthanum fluoride (LaF3)) composites; (4) nickel - rare-earth-oxide composites and nickel - rare-earth-oxide - rare-earth-fluoride composites. For comparison purposes, a currently used metal-ceramic composite was also studied. Results showed that the nickel-Gd2O3 and nickel-La2O3-LaF3 composites were comparable or superior in friction and wear performance to the currently used composite and therefore deserve to be considered for further development.

How weak is the subduction zone interface?

NARCIS (Netherlands)

Duarte, João C.; Schellart, Wouter P.; Cruden, Alexander R.

2015-01-01

Several lines of evidence suggest that subduction zones are weak and that the unique availability of water on Earth is a critical factor in the weakening process. We have evaluated the strength of subduction zone interfaces using two approaches: (i) from empirical relationships between shear stress

New approach to nonleptonic weak interactions. I. Derivation of asymptotic selection rules for the two-particle weak ground-state-hadron matrix elements

International Nuclear Information System (INIS)

Tanuma, T.; Oneda, S.; Terasaki, K.

1984-01-01

A new approach to nonleptonic weak interactions is presented. It is argued that the presence and violation of the Vertical BarΔIVertical Bar = 1/2 rule as well as those of the quark-line selection rules can be explained in a unified way, along with other fundamental physical quantities [such as the value of g/sub A/(0) and the smallness of the isoscalar nucleon magnetic moments], in terms of a single dynamical asymptotic ansatz imposed at the level of observable hadrons. The ansatz prescribes a way in which asymptotic flavor SU(N) symmetry is secured levelwise for a certain class of chiral algebras in the standard QCD model. It yields severe asymptotic constraints upon the two-particle hadronic matrix elements of nonleptonic weak Hamiltonians as well as QCD currents and their charges. It produces for weak matrix elements the asymptotic Vertical BarΔIVertical Bar = 1/2 rule and its charm counterpart for the ground-state hadrons, while for strong matrix elements quark-line-like approximate selection rules. However, for the less important weak two-particle vertices involving higher excited states, the Vertical BarΔIVertical Bar = 1/2 rule and its charm counterpart are in general violated, providing us with an explicit source of the violation of these selection rules in physical processes

Evaluation of HIV testing algorithms in Ethiopia: the role of the tie-breaker algorithm and weakly reacting test lines in contributing to a high rate of false positive HIV diagnoses.

Science.gov (United States)

Shanks, Leslie; Siddiqui, M Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Pirou, Erwan; Ritmeijer, Koert; Masiga, Johnson; Abebe, Almaz

2015-02-03

In Ethiopia a tiebreaker algorithm using 3 rapid diagnostic tests (RDTs) in series is used to diagnose HIV. Discordant results between the first 2 RDTs are resolved by a third 'tiebreaker' RDT. Médecins Sans Frontières uses an alternate serial algorithm of 2 RDTs followed by a confirmation test for all double positive RDT results. The primary objective was to compare the performance of the tiebreaker algorithm with a serial algorithm, and to evaluate the addition of a confirmation test to both algorithms. A secondary objective looked at the positive predictive value (PPV) of weakly reactive test lines. The study was conducted in two HIV testing sites in Ethiopia. Study participants were recruited sequentially until 200 positive samples were reached. Each sample was re-tested in the laboratory on the 3 RDTs and on a simple to use confirmation test, the Orgenics Immunocomb Combfirm® (OIC). The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. 2620 subjects were included with a HIV prevalence of 7.7%. Each of the 3 RDTs had an individual specificity of at least 99%. The serial algorithm with 2 RDTs had a single false positive result (1 out of 204) to give a PPV of 99.5% (95% CI 97.3%-100%). The tiebreaker algorithm resulted in 16 false positive results (PPV 92.7%, 95% CI: 88.4%-95.8%). Adding the OIC confirmation test to either algorithm eliminated the false positives. All the false positives had at least one weakly reactive test line in the algorithm. The PPV of weakly reacting RDTs was significantly lower than those with strongly positive test lines. The risk of false positive HIV diagnosis in a tiebreaker algorithm is significant. We recommend abandoning the tie-breaker algorithm in favour of WHO recommended serial or parallel algorithms, interpreting weakly reactive test lines as indeterminate results requiring further testing except in the setting of blood transfusion, and most importantly, adding a confirmation test

Limb-darkening coefficients from line-blanketed non-LTE hot-star model atmospheres

Science.gov (United States)

Reeve, D. C.; Howarth, I. D.

2016-02-01

We present grids of limb-darkening coefficients computed from non-local thermodynamic equilibrium (non-LTE), line-blanketed TLUSTY model atmospheres, covering effective-temperature and surface-gravity ranges of 15-55 kK and 4.75 dex (cgs) down to the effective Eddington limit, at 2×, 1×, 0.5× (Large Magellanic Cloud), 0.2× (Small Magellanic Cloud), and 0.1× solar. Results are given for the Bessell UBVRICJKHL, Sloan ugriz, Strömgren ubvy, WFCAM ZYJHK, Hipparcos, Kepler, and Tycho passbands, in each case characterized by several different limb-darkening `laws'. We examine the sensitivity of limb darkening to temperature, gravity, metallicity, microturbulent velocity, and wavelength, and make a comparison with LTE models. The dependence on metallicity is very weak, but limb darkening is a moderately strong function of log g in this temperature regime.

Evaluation of different finish line designs in base metal alloys

Directory of Open Access Journals (Sweden)

Aghandeh R

1999-06-01

Full Text Available This investigation was performed according to the widespread application of base metal alloys"nand few articles published about the marginal integrity of restorations fabricated by these metals."nThree standard dies of a maxillary first premolar were prepared with a flat shoulder finish line in buccal"naspect and chamfer in palatal. One of them left with no change. On the buccal aspect of the second and"nthird dies 135?and 1607 bevel were added respectively"nUsing dual wax technique, nine wax patterns were formed on each die and casting procedure of selected"nnon precious alloy was performed by centrifugal method. Marginal gaps of each copping seated on dies"nwere measured by scanning electron microscope (SEM with X500 magnification. Measurements were"ndone on three areas of marked dies on buccal aspect. Measurement son palatal aspect was done on"nmarked midpalatal point as control."nResults and statistical analysis showed no significant difference among marginal gaps in lingual aspect."nBut on the buccal aspect there were statistically significant differences among the groups (P<0.001. Flat"nshoulder had the best marginal integrity (mean 4 micron. Shoulder with 160' bevel had the most marginal"ngap (mean 26.5 micron and shoulder with 1357 bevel was between two other groups (mean 15.7 micron.

Theoretical pulsation of metallic-line stars

International Nuclear Information System (INIS)

Cox, A.N.; King, D.S.; Hodson, S.W.

1979-01-01

The linear-theory radial-pulsation stability of low-helium delta Scuti variable models (1.0--2.5 Msun) has been investigated to see if metallicism and pulsation can occur simultaneously. Metallicism, which occurs in slowly rotating stars after the gravitational settling of He and the loss of the He II convection zone and its deep mixing for Y< or approx. =0.1, can then be established rapidly compared with the evolution time scale. Pulsation can still occur with driving due to the residual helium and the enhanced hydrogen. With the reduced helium giving no connection zone, the pulsation instability strip, whose blue and edges are estimated in this paoer, is about half as wide as with a normal helium abundance. Zero helium in the surface driving regions, however, produces blue edges so red that probably no instability strip exists at all. The red edge, predicted theoretically on the basis of the importance of convection in the outer zone, agrees well with the observational one. Cool, low-helium and metallic-line stars are then predicted to pulsate in a 200--500 K wide strip that is widest between the main-sequence luminosity of 5 Lsun and 15 Lsun. This strip reasonably includes the observed pulsating delta Del and mild Am stars, but there may be conflicts. Since blue edges for varying ionization-zone helium content occur across the entire instability strip, bluer first and higher overtone pulsations are also predicted everywhere from less than 7000 K to over 8000 K, the redder ones probably showing metallicism

Reconstructing weak values without weak measurements

International Nuclear Information System (INIS)

Johansen, Lars M.

2007-01-01

I propose a scheme for reconstructing the weak value of an observable without the need for weak measurements. The post-selection in weak measurements is replaced by an initial projector measurement. The observable can be measured using any form of interaction, including projective measurements. The reconstruction is effected by measuring the change in the expectation value of the observable due to the projector measurement. The weak value may take nonclassical values if the projector measurement disturbs the expectation value of the observable

Spatially Resolved HST Grism Spectroscopy of a Lensed Emission Line Galaxy at z ~ 1

Science.gov (United States)

Frye, Brenda L.; Hurley, Mairead; Bowen, David V.; Meurer, Gerhardt; Sharon, Keren; Straughn, Amber; Coe, Dan; Broadhurst, Tom; Guhathakurta, Puragra

2012-07-01

We take advantage of gravitational lensing amplification by A1689 (z = 0.187) to undertake the first space-based census of emission line galaxies (ELGs) in the field of a massive lensing cluster. Forty-three ELGs are identified to a flux of i 775 = 27.3 via slitless grism spectroscopy. One ELG (at z = 0.7895) is very bright owing to lensing magnification by a factor of ≈4.5. Several Balmer emission lines (ELs) detected from ground-based follow-up spectroscopy signal the onset of a major starburst for this low-mass galaxy (M * ≈ 2 × 109 M ⊙) with a high specific star formation rate (≈20 Gyr-1). From the blue ELs we measure a gas-phase oxygen abundance consistent with solar (12+log(O/H) = 8.8 ± 0.2). We break the continuous line-emitting region of this giant arc into seven ~1 kpc bins (intrinsic size) and measure a variety of metallicity-dependent line ratios. A weak trend of increasing metal fraction is seen toward the dynamical center of the galaxy. Interestingly, the metal line ratios in a region offset from the center by ~1 kpc have a placement on the blue H II region excitation diagram with f ([O III])/f (Hβ) and f ([Ne III])/f (Hβ) that can be fitted by an active galactic nucleus (AGN). This asymmetrical AGN-like behavior is interpreted as a product of shocks in the direction of the galaxy's extended tail, possibly instigated by a recent galaxy interaction. Based, in part, on data obtained with the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

BCS superconductivity for weakly coupled clusters

International Nuclear Information System (INIS)

Friedel, J.

1992-01-01

BCS superconductivity is expected to have fairly high critical temperatures when clusters of moderate sizes are weakly coupled to form a crystal. This remark extends to quasi zerodimensional cases, a remark initially made by Labbe for quasi one-dimensional ones and by Hirsch, Bok and Labbe for quasi twodimensional ones. Possible applications are envisaged for twodimensional clusters (fullerene) or threedimensional ones (metal clusters, Chevrel phases). Conditions for optimal applicability of the scheme are somewhat restricted. (orig.)

The Discovery of a High-Redshift Quasar without Emission Lines from Sloan Digital Sky Survey Commissioning Data.

Science.gov (United States)

Fan; Strauss; Gunn; Lupton; Carilli; Rupen; Schmidt; Moustakas; Davis; Annis; Bahcall; Brinkmann; Brunner; Csabai; Doi; Fukugita; Heckman; Hennessy; Hindsley; Ivezic; Knapp; Lamb; Munn; Pauls; Pier; Rockosi; Schneider; Szalay; Tucker; York

1999-12-01

We report observations of a luminous unresolved object at redshift z=4.62, with a featureless optical spectrum redward of the Lyalpha forest region, discovered from Sloan Digital Sky Survey commissioning data. The redshift is determined by the onset of the Lyalpha forest at lambda approximately 6800 Å and a Lyman limit system at lambda=5120 Å. A strong Lyalpha absorption system with weak metal absorption lines at z=4.58 is also identified in the spectrum. The object has a continuum absolute magnitude of -26.6 at 1450 Å in the rest frame (h0=0.5, q0=0.5) and therefore cannot be an ordinary galaxy. It shows no radio emission (the 3 sigma upper limit of its flux at 6 cm is 60 µJy), indicating a radio-to-optical flux ratio at least as small as that of the radio-weakest BL Lacertae objects known. It is also not linearly polarized to a 3 sigma upper limit of 4% in the observed I band. Therefore, it is either the most distant BL Lac object known to date, with very weak radio emission, or a new type of unbeamed quasar, whose broad emission line region is very weak or absent.

Weak interactions of quarks and leptons: experimental status

International Nuclear Information System (INIS)

Wojcicki, S.

1984-09-01

The present experimental status of weak interactions is discussed with emphasis on the problems and questions and on the possible lines of future investigations. Major topics include; (1) the quark mixing matrix, (2) CP violation, (3) rare decays, (4) the lepton sector, and (5) right handed currents. 118 references

Hunting for Intrinsically X-ray Weak Quasars: The Case of PHL 1811 Analogs

Science.gov (United States)

Brandt, William

2009-09-01

A central dogma of X-ray astronomy is that luminous X-ray emission is a universal property of efficiently accreting supermassive black holes. One interesting challenge to this idea has come from the quasar PHL 1811 which appears to be intrinsically X-ray weak and also has distinctive emission-line properties. We propose to observe a sample of eight SDSS quasars, selected to have similar UV emission-line properties to that of PHL 1811, to test if they are also X-ray weak. Our analyses of the currently available X-ray data appear to support this hypothesis but do not provide a proper test. Our results will have implications for the nature of accretion-disk coronae, emission-line formation, and AGN selection.

Characterization of appendage weld quality by on line monitoring of electrical parameters

Energy Technology Data Exchange (ETDEWEB)

Setty, D.S.; Somani, A.K.; Ram, A.M.; Rao, A.R.; Jayaraj, R.N.; Kalidas, R. [Nuclear Fuel Complex, Dept. of Atomic Energy, Hyderabad (India)

2005-07-01

Resistance projection welding of zirconium alloy appendages is one of the most critical processes in the PHWR fuel fabrication. Appendages like Spacers and Bearing pads having multi projections are joined to the fuel sheath using capacitor discharge power source. Variations in the projection sizes, weld parameters and cleanliness of the work pieces have significant effect on the weld quality, in addition to material properties like hardness, tensile strength and surface finish. Defects like metal expulsion and weak welds are occasionally observed in appendage welding process, which need to be identified and segregated. Though numerous off-line inspection methods are available for the weld quality evaluation, on-line monitoring of weld quality is essential for identifying defective welds. For this purpose, various monitoring techniques like acoustic emission, analyzing derived electrical parameters and weld upset/deformation measurements are employed. The derived electrical parameters like A{sup 2}-Sec and Ohm-Sec can also be monitored. The present paper highlights development of suitable acceptance criteria for the monitoring technique by employing derived electrical parameters covering a wide range of weld variables like watt-sec and squeeze force. Excellent correlation could be achieved in identifying the weak welds and weld expulsion defects in mass production. (author)

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

Science.gov (United States)

Gandhi, P.; Annuar, A.; Lansbury, G. B.; Stern, D.; Alexander, D. M.; Bauer, F. E.; Bianchi, S.; Boggs, S. E.; Boorman, P. G.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Comastri, A.; Craig, W. W.; Del Moro, A.; Elvis, M.; Guainazzi, M.; Hailey, C. J.; Harrison, F. A.; Koss, M.; Lamperti, I.; Malaguti, G.; Masini, A.; Matt, G.; Puccetti, S.; Ricci, C.; Rivers, E.; Walton, D. J.; Zhang, W. W.

2017-06-01

We present NuSTAR X-ray observations of the active galactic nucleus (AGN) in NGC 7674. The source shows a flat X-ray spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested the alternate possibility that the source is a recently switched-off AGN with the observed X-rays being the lagged echo from the torus. Our high-quality data show the source to be reflection-dominated in hard X-rays, but with a relatively weak neutral Fe Kα emission line (equivalent width [EW] of ≈ 0.4 keV) and a strong Fe xxvi ionized line (EW ≈ 0.2 keV). We construct an updated long-term X-ray light curve of NGC 7674 and find that the observed 2-10 keV flux has remained constant for the past ≈ 20 yr, following a high-flux state probed by Ginga. Light travel time arguments constrain the minimum radius of the reflector to be ˜ 3.2 pc under the switched-off AGN scenario, ≈ 30 times larger than the expected dust sublimation radius, rendering this possibility unlikely. A patchy Compton-thick AGN (CTAGN) solution is plausible, requiring a minimum line-of-sight column density (NH) of 3 × 1024 cm-2 at present, and yields an intrinsic 2-10 keV luminosity of (3-5) × 1043 erg s-1. Realistic uncertainties span the range of ≈ (1-13) × 1043 erg s-1. The source has one of the weakest fluorescence lines amongst bona fide CTAGN, and is potentially a local analogue of bolometrically luminous systems showing complex neutral and ionized Fe emission. It exemplifies the difficulty of identification and proper characterization of distant CTAGN based on the strength of the neutral Fe Kα line.

The Weak Fe Fluorescence Line and Long-Term X-Ray Evolution of the Compton-Thick Active Galactic Nucleus in NGC7674

Science.gov (United States)

Ghandi, P.; Annuar, A.; Lansbury, G. B.; Stern, D.; Alexander, D. M.; Bauer, F. E.; Bianchi, S.; Boggs, S. E.; Boorman, P. G.; Brandt, W. N.;

Long-term rupture strength as a criterion of operational durability of steam line metal

International Nuclear Information System (INIS)

Gofman, Yu.M.

2000-01-01

The method for substantiation of the steam line service life prolongation, depending on the achieved level of the metal vulnerability to damage, is proposed. The methodology for evaluating the metal state is developed on the basis of the durability bond with the level of the vulnerability to damage through micropores and the ferrite dislocation structure state. The main changes in the metal at the 1-3 stages of its creep are presented. The micropores are absent at the 1 stage. the micropores of about 0.1 μm in diameter are identified at the beginning of the 2 stage. The ferrite grains on the transition from the 2 to the 3 creep stage are mainly fragmentary. There takes place further micropores growth on the grain boundaries up to 1 - 3 μm. Significant number of recrystallized volumes in the ferrite is observed at the 3 creep stage. The number of micropores of 1 - 3μm in size sharply increases, and, as a rule, chains of micropores are observed. The pores of 5 μm in size are formed at the pre-destruction stage, the fusion whereof leads to microcracks formation [ru

Probing Pre-Galactic Metal Enrichment with High-Redshift Gamma-Ray Bursts

Science.gov (United States)

Wang, F. Y.; Bromm, Volker; Greif, Thomas H.; Stacy, Athena; Dai, Z. G.; Loeb, Abraham; Cheng, K. S.

2012-01-01

We explore high-redshift gamma-ray bursts (GRBs) as promising tools to probe pre-galactic metal enrichment. We utilize the bright afterglow of a Population III (Pop III) GRB exploding in a primordial dwarf galaxy as a luminous background source, and calculate the strength of metal absorption lines that are imprinted by the first heavy elements in the intergalactic medium (IGM). To derive the GRB absorption line diagnostics, we use an existing highly resolved simulation of the formation of a first galaxy which is characterized by the onset of atomic hydrogen cooling in a halo with virial temperature approximately greater than10(exp 4) K.We explore the unusual circumburst environment inside the systems that hosted Pop III stars, modeling the density evolution with the self-similar solution for a champagne flow. For minihalos close to the cooling threshold, the circumburst density is roughly proportional to (1 + z) with values of about a few cm(exp -3). In more massive halos, corresponding to the first galaxies, the density may be larger, n approximately greater than100 cm(exp -3). The resulting afterglow fluxes are weakly dependent on redshift at a fixed observed time, and may be detectable with the James Webb Space Telescope and Very Large Array in the near-IR and radio wavebands, respectively, out to redshift z approximately greater than 20. We predict that the maximum of the afterglow emission shifts from near-IR to millimeter bands with peak fluxes from mJy to Jy at different observed times. The metal absorption line signature is expected to be detectable in the near future. GRBs are ideal tools for probing the metal enrichment in the early IGM, due to their high luminosities and featureless power-law spectra. The metals in the first galaxies produced by the first supernova (SN) explosions are likely to reside in low-ionization stages (C II, O I, Si II and Fe II). We show that, if the afterglow can be observed sufficiently early, analysis of the metal lines may

Possible stibnite transformation at the friction surface of the semi-metallic friction composites designed for car brake linings

Science.gov (United States)

Matějka, V.; Lu, Y.; Matějková, P.; Smetana, B.; Kukutschová, J.; Vaculík, M.; Tomášek, V.; Zlá, S.; Fan, Y.

2011-12-01

After a friction process several changes in phase composition of friction composites are often registered. High temperature, accompanied by high pressure induced during braking can cause initiation of chemical reactions which do not run at room or elevated temperatures under the atmospheric pressure. Most of the studies in the field of tribochemistry at friction surfaces of automotive semi-metallic brake linings deal with phenolic resin degradation and corrosion of metallic components. The paper addresses the formation of elemental antimony as well as the alloying process of iron with antimony observed on the surface of laboratory prepared semi-metallic friction composites containing stibnite. The role of alumina abrasives in the process of stibnite transformation is also discussed and mechanism of stibnite transformation was outlined.

Source term analysis for a criticality accident in metal production line glove boxes

International Nuclear Information System (INIS)

Nguyen, D.H.

1991-06-01

A recent development in criticality accident analysis is the deterministic calculations of the transport of fission products and actinides through the barriers of the physical facility. The knowledge of the redistribution of the materials inside the facility will help determine the reentry and clean-up procedures. The amount of radioactive materials released to the environment is the source term for dispersion calculations. We have used an integrated computer model to determine the release of fission products to the environment from a hypothetical criticality event in a glove box of the metal production line (MPL) at the Lawrence Livermore National Laboratory (LLNL)

Production of metal particles and clusters

Science.gov (United States)

Mcmanus, S. P.

1982-01-01

The feasibility of producing novel metals or metal clusters in a low gravity environment was studied. The production of coordinately unsaturated metal carbonyls by thermolysis or photolysis of stable metal carbonyls has the potential to generate novel catalysts by this technique. Laser irradiation of available metal carbonyls was investigated. It is found that laser induced decomposition of metal carbonyls is feasible for producing a variety of coordinately unsaturated species. Formation of clustered species does occur but is hampered by weak metal-metal bonds.

Study of the weak localization in high quality two dimensional p-GaAs/AIGaAs systems

International Nuclear Information System (INIS)

Yasin, C.E.; Simmons, M.Y.; Hamilton, A.R.; Pepper, M.; Ritchie, D.A.

2002-01-01

Full text: Despite numerous experimental and theoretical work over the past ∼ 30 years, the nature of the ground state in 2D semiconductor systems remains a subject of controversy. Does the anomalous 'metallic' behavior observed at B = 0 imply the existence of a new 2D 'metallic' ground state or can it be explained within the conventional Fermi liquid theory? To address this question, we have investigated the single particle phase coherent 'weak localization' effect in high quality 2D p-GaAs systems that shows an apparent ' metallic' behavior at B = 0. We have performed detailed temperature dependent magnetoresistance measurements at different carrier densities and fit the experimental data to various models of weak localization in order to extract the phase coherence time, τ φ . We find that as the sample quality increases the mean free path increases, and weak localization must be treated beyond the diffusion approximation, making the data analysis more complex. Our result shows that when these more complex models are applied to the experimental data the systems are well described by Fermi liquid theory despite the strong interactions (r s ∼ 20), indicating that there is no 'metallic' phase in 2D at B = 0

On the role of weak interface in crack blunting process in nanoscale layered composites

Science.gov (United States)

Li, Yi; Zhou, Qing; Zhang, Shuang; Huang, Ping; Xu, Kewei; Wang, Fei; Lu, Tianjian

2018-03-01

Heterointerface in a nanoscale metallic layered composite could improve its crack resistance. However, the influence of metallic interface structures on crack propagation has not been well understood at atomic scale. By using the method of molecular dynamics (MD) simulation, the crack propagation behavior in Cu-Nb bilayer is compared with that in Cu-Ni bilayer. We find that the weak Cu-Nb interface plays an important role in hindering crack propagation in two ways: (i) dislocation nucleation at the interface releases stress concentration for the crack to propagate; (ii) the easily sheared weak incoherent interface blunts the crack tip. The results are helpful for understanding the interface structure dependent crack resistance of nanoscale bicrystal interfaces.

Photosynthesis and chlorophyll fluorescence reaction to different shade stresses of weak light sensitive maize

International Nuclear Information System (INIS)

Wang, J.; Li, F.; Shi, Z.; Huang, H.; Jia, S.

2017-01-01

A split-plot experimental study was conducted to evaluate the effect of different shade stresses on photosynthesis and chlorophyll fluorescence of maize leaves.The experiment was designed on the south farm of Special Corn Institute, Shenyang Agricultural University, China.Data was collected from the day maize tasseled (Jul. 21) to the beginning of grouting (Aug.12 ) under 18%, 28%, 38%, 60%, and 75% shade stress to determine indexes such as photosynthesis and chlorophyll fluorescence after 15 days of shade treatment. Pairs of near-isogenic lines (NILs) of Shennong 98A (a barren stalk inbred line) and Shennong 98B (an un-barren stalk inbred line) were used as experimental materials to further reveal photosynthetic mechanisms of weak light sensitive maize when exposed to weak light conditions. Thus, a foundation was established for high density-resistant (shade resistant) corn breeding,while identifying weak light sensitive varieties. After shading treatment, chlorophyll a and total chlorophyll content of both varieties increased, chlorophyll b content first increased, followed by a decrease, while the net photosynthetic rate and stomatal conductance showed a gradually decreasing trend. The changing trends of photochemical quenching coefficient(qp) and effective quantum yield of PSII photochemistry (FPSII)were similar, FPSII and qP increased significantly as shading stress increased from 18% to 38%;however, FPSII and qP declined significantly under 60% and 75% shading stresses. The changing trend of NPQ was opposite to FPSII and qP. A comparison of both inbred lines showed that photosynthesis and chlorophyll fluorescence characteristics of Shennong 98B were superior to Shennong 98A. This study revealed the relationships between weak light sensitive lines and shade intensities by comparing differences in photosynthesis and chlorophyll fluorescence parameters. (author)

Weak hard X-ray emission from two broad absorption line quasars observed with NuSTAR: Compton-thick absorption or intrinsic X-ray weakness?

DEFF Research Database (Denmark)

Luo, B.; Brandt, W. N.; Alexander, D. M.

2013-01-01

are not significantly absorbed (NH ≲ 1024 cm-2). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain...... likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place...

Temperature-dependence of Threshold Current Density-Length Product in Metallization Lines: A Revisit

International Nuclear Information System (INIS)

Duryat, Rahmat Saptono; Kim, Choong-Un

2016-01-01

One of the important phenomena in Electromigration (EM) is Blech Effect. The existence of Threshold Current Density-Length Product or EM Threshold has such fundamental and technological consequences in the design, manufacture, and testing of electronics. Temperature-dependence of Blech Product had been thermodynamically established and the real behavior of such interconnect materials have been extensively studied. The present paper reviewed the temperature-dependence of EM threshold in metallization lines of different materials and structure as found in relevant published articles. It is expected that the reader can see a big picture from the compiled data, which might be overlooked when it was examined in pieces. (paper)

Recent advances in on-line coupling of capillary electrophoresis to atomic absorption and fluorescence spectrometry for speciation analysis and studies of metal-biomolecule interactions

International Nuclear Information System (INIS)

Li Yan; Yin Xuebo; Yan Xiuping

2008-01-01

Speciation information is vital for the understanding of the toxicity, mobility and bioavailability of elements in environmental or biological samples. Hyphenating high resolving power of separation techniques and element-selective detectors provides powerful tools for studying speciation of trace elements in environmental and biological systems. During the last five years several novel hybrid techniques based on capillary electrophoresis (CE) and atomic spectrometry have been developed for speciation analysis and metal-biomolecule interaction study in our laboratory. These techniques include CE on-line coupled with atomic fluorescence spectrometry (AFS), chip-CE on-line coupled with AFS, CE on-line coupled with flame heated quartz furnace atomic absorption spectrometry (FHF-AAS), and CE on-line coupled with electrothermal atomic absorption spectrometry (ETAAS). The necessity for the development of these techniques, their interface design, and applications in speciation analysis and metal-biomolecule interaction study are reviewed. The advantages and limitations of the developed hybrid techniques are critically discussed, and further development is also prospected

SDSS-IV MaNGA: environmental dependence of stellar age and metallicity gradients in nearby galaxies

Science.gov (United States)

Zheng, Zheng; Wang, Huiyuan; Ge, Junqiang; Mao, Shude; Li, Cheng; Li, Ran; Mo, Houjun; Goddard, Daniel; Bundy, Kevin; Li, Hongyu; Nair, Preethi; Lin, Lihwai; Long, R. J.; Riffel, Rogério; Thomas, Daniel; Masters, Karen; Bizyaev, Dmitry; Brownstein, Joel R.; Zhang, Kai; Law, David R.; Drory, Niv; Roman Lopes, Alexandre; Malanushenko, Olena

2017-03-01

We present a study on the stellar age and metallicity distributions for 1105 galaxies using the STARLIGHT software on MaNGA (Mapping Nearby Galaxies at APO) integral field spectra. We derive age and metallicity gradients by fitting straight lines to the radial profiles, and explore their correlations with total stellar mass M*, NUV - r colour and environments, as identified by both the large-scale structure (LSS) type and the local density. We find that the mean age and metallicity gradients are close to zero but slightly negative, which is consistent with the inside-out formation scenario. Within our sample, we find that both the age and metallicity gradients show weak or no correlation with either the LSS type or local density environment. In addition, we also study the environmental dependence of age and metallicity values at the effective radii. The age and metallicity values are highly correlated with M* and NUV - r and are also dependent on LSS type as well as local density. Low-mass galaxies tend to be younger and have lower metallicity in low-density environments while high-mass galaxies are less affected by environment.

Laser line scan underwater imaging by complementary metal-oxide-semiconductor camera

Science.gov (United States)

He, Zhiyi; Luo, Meixing; Song, Xiyu; Wang, Dundong; He, Ning

2017-12-01

This work employs the complementary metal-oxide-semiconductor (CMOS) camera to acquire images in a scanning manner for laser line scan (LLS) underwater imaging to alleviate backscatter impact of seawater. Two operating features of the CMOS camera, namely the region of interest (ROI) and rolling shutter, can be utilized to perform image scan without the difficulty of translating the receiver above the target as the traditional LLS imaging systems have. By the dynamically reconfigurable ROI of an industrial CMOS camera, we evenly divided the image into five subareas along the pixel rows and then scanned them by changing the ROI region automatically under the synchronous illumination by the fun beams of the lasers. Another scanning method was explored by the rolling shutter operation of the CMOS camera. The fun beam lasers were turned on/off to illuminate the narrow zones on the target in a good correspondence to the exposure lines during the rolling procedure of the camera's electronic shutter. The frame synchronization between the image scan and the laser beam sweep may be achieved by either the strobe lighting output pulse or the external triggering pulse of the industrial camera. Comparison between the scanning and nonscanning images shows that contrast of the underwater image can be improved by our LLS imaging techniques, with higher stability and feasibility than the mechanically controlled scanning method.

Active galactic nuclei emission line diagnostics and the mass-metallicity relation up to redshift z ∼ 2: The impact of selection effects and evolution

Energy Technology Data Exchange (ETDEWEB)

Juneau, Stéphanie; Bournaud, Frédéric; Daddi, Emanuele; Elbaz, David; Duc, Pierre-Alain; Gobat, Raphael; Jean-Baptiste, Ingrid; Le Floc' h, Émeric; Pannella, Maurilio; Schreiber, Corentin [CEA-Saclay, DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France); Charlot, Stéphane; Lehnert, M. D.; Pacifici, Camilla [UPMC-CNRS, UMR 7095, Institut d' Astrophysique de Paris, F-75014 Paris (France); Trump, Jonathan R. [University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Brinchmann, Jarle [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Dickinson, Mark, E-mail: stephanie.juneau@cea.fr [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

2014-06-10

Emission line diagnostic diagrams probing the ionization sources in galaxies, such as the Baldwin-Phillips-Terlevich (BPT) diagram, have been used extensively to distinguish active galactic nuclei (AGN) from purely star-forming galaxies. However, they remain poorly understood at higher redshifts. We shed light on this issue with an empirical approach based on a z ∼ 0 reference sample built from ∼300,000 Sloan Digital Sky Survey galaxies, from which we mimic selection effects due to typical emission line detection limits at higher redshift. We combine this low-redshift reference sample with a simple prescription for luminosity evolution of the global galaxy population to predict the loci of high-redshift galaxies on the BPT and Mass-Excitation (MEx) diagnostic diagrams. The predicted bivariate distributions agree remarkably well with direct observations of galaxies out to z ∼ 1.5, including the observed stellar mass-metallicity (MZ) relation evolution. As a result, we infer that high-redshift star-forming galaxies are consistent with having normal interstellar medium (ISM) properties out to z ∼ 1.5, after accounting for selection effects and line luminosity evolution. Namely, their optical line ratios and gas-phase metallicities are comparable to that of low-redshift galaxies with equivalent emission-line luminosities. In contrast, AGN narrow-line regions may show a shift toward lower metallicities at higher redshift. While a physical evolution of the ISM conditions is not ruled out for purely star-forming galaxies and may be more important starting at z ≳ 2, we find that reliably quantifying this evolution is hindered by selections effects. The recipes provided here may serve as a basis for future studies toward this goal. Code to predict the loci of galaxies on the BPT and MEx diagnostic diagrams and the MZ relation as a function of emission line luminosity limits is made publicly available.

Active galactic nuclei emission line diagnostics and the mass-metallicity relation up to redshift z ∼ 2: The impact of selection effects and evolution

International Nuclear Information System (INIS)

Juneau, Stéphanie; Bournaud, Frédéric; Daddi, Emanuele; Elbaz, David; Duc, Pierre-Alain; Gobat, Raphael; Jean-Baptiste, Ingrid; Le Floc'h, Émeric; Pannella, Maurilio; Schreiber, Corentin; Charlot, Stéphane; Lehnert, M. D.; Pacifici, Camilla; Trump, Jonathan R.; Brinchmann, Jarle; Dickinson, Mark

2014-01-01

Emission line diagnostic diagrams probing the ionization sources in galaxies, such as the Baldwin-Phillips-Terlevich (BPT) diagram, have been used extensively to distinguish active galactic nuclei (AGN) from purely star-forming galaxies. However, they remain poorly understood at higher redshifts. We shed light on this issue with an empirical approach based on a z ∼ 0 reference sample built from ∼300,000 Sloan Digital Sky Survey galaxies, from which we mimic selection effects due to typical emission line detection limits at higher redshift. We combine this low-redshift reference sample with a simple prescription for luminosity evolution of the global galaxy population to predict the loci of high-redshift galaxies on the BPT and Mass-Excitation (MEx) diagnostic diagrams. The predicted bivariate distributions agree remarkably well with direct observations of galaxies out to z ∼ 1.5, including the observed stellar mass-metallicity (MZ) relation evolution. As a result, we infer that high-redshift star-forming galaxies are consistent with having normal interstellar medium (ISM) properties out to z ∼ 1.5, after accounting for selection effects and line luminosity evolution. Namely, their optical line ratios and gas-phase metallicities are comparable to that of low-redshift galaxies with equivalent emission-line luminosities. In contrast, AGN narrow-line regions may show a shift toward lower metallicities at higher redshift. While a physical evolution of the ISM conditions is not ruled out for purely star-forming galaxies and may be more important starting at z ≳ 2, we find that reliably quantifying this evolution is hindered by selections effects. The recipes provided here may serve as a basis for future studies toward this goal. Code to predict the loci of galaxies on the BPT and MEx diagnostic diagrams and the MZ relation as a function of emission line luminosity limits is made publicly available.

High Resolution Studies Of Lensed z ∼ 2 Galaxies: Kinematics And Metal Gradients

Science.gov (United States)

Leethochawalit, Nicha

2016-09-01

We use the OSIRIS integral field unit (IFU) spectograph to secure spatially-resolved strong emission lines of 15 gravitationally-lensed star-forming galaxies at redshift z ∼ 2. With the aid of gravitational lensing and Keck laser-assisted adaptive optics, the spatial resolution of these sub-luminous galaxies is at a few hundred parsecs. First, we demonstrate that high spatial resolution is crucial in diagnosing the kinematic properties and dynamical maturity of z ∼ 2 galaxies. We observe a significantly lower fraction of rotationally-supported systems than what has been claimed in lower spatial resolution surveys. Second, we find a much larger fraction of z ∼ 2 galaxies with weak metallicity gradients, contrary to the simple picture suggested by earlier studies that well-ordered rotation develops concurrently with established steep metal gradients in all but merging systems. Comparing our observations with the predictions of hydronamical simulations, strong feedback is likely to play a key role in flattening metal gradients in early star-forming galaxies.

Metal-metal interaction mediates the iron induction of Drosophila MtnB

International Nuclear Information System (INIS)

Qiang, Wenjia; Huang, Yunpeng; Wan, Zhihui; Zhou, Bing

2017-01-01

Metallothionein (MT) protein families are a class of small and universal proteins rich in cysteine residues. They are synthesized in response to heavy metal stresses to sequester the toxic ions by metal-thiolate bridges. Five MT family members, namely MtnA, MtnB, MtnC, MtnD and MtnE, have been discovered and identified in Drosophila. These five isoforms of MTs are regulated by metal responsive transcription factor dMTF-1 and play differentiated but overlapping roles in detoxification of metal ions. Previous researches have shown that Drosophila MtnB responds to copper (Cu), cadmium (Cd) and zinc (Zn). Interestingly in this study we found that Drosophila MtnB expression also responds to elevated iron levels in the diet. Further investigations revealed that MtnB plays limited roles in iron detoxification, and the direct binding of MtnB to ferrous iron in vitro is also weak. The induction of MtnB by iron turns out to be mediated by iron interference of other metals, because EDTA at even a partial concentration of that of iron can suppress this induction. Indeed, in the presence of iron, zinc homeostasis is altered, as reflected by expression changes of zinc transporters dZIP1 and dZnT1. Thus, iron-mediated MtnB induction appears resulting from interrupted homeostasis of other metals such as zinc, which in turns induced MtnB expression. Metal-metal interaction may more widely exist than we expected. - Highlights: • Metallothionein B expression is regulated by iron in Drosophila melanogaster. • MtnB has limited physiological roles in iron detoxification. • Binding affinity of MtnB to iron is weak in vitro. • Induction of Drosophila MtnB by iron is mediated indirectly through metal-metal interaction.

Plastic flow in weak shock waves in uranium

International Nuclear Information System (INIS)

Tonks, D.L.

1992-01-01

Measurements of the particle velocity in weak shock waves in metals are available for a number of materials. These measurements use the laser interferometer or VISAR technique in conjunction with a plate impact experiment. These measurements are important for determining the elastic -- plastic behavior of materials at high strain rates. Strain rates up to 10 7 /s are measurable with this technique, while more conventional mechanical testing machines, such as the Hopkinson bar, achieve rates only up to about 10 4 /s. In this paper, the VISAR measurements of Grady on uranium are analyzed using the weak shock analysis of Wallace to extract the plastic and total strains, the deviatoric and total stresses, and the plastic strain rates. A brief error analysis of the results will be given. 7 refs

Metal enrichment of the neutral gas of blue compact dwarf galaxies: the compelling case of Pox 36

Science.gov (United States)

Lebouteiller, V.; Kunth, D.; Thuan, T. X.; Désert, J. M.

2009-02-01

Context: Evidence has grown over the past few years that the neutral phase of blue compact dwarf (BCD) galaxies may be metal-deficient as compared to the ionized gas of their H ii regions. These results have strong implications for our understanding of the chemical evolution of galaxies, and it is essential to strengthen the method, as well as to find possible explanations. Aims: We present the analysis of the interstellar spectrum of Pox 36 with the Far Ultraviolet Spectroscopic Explorer (FUSE). Pox 36 was selected because of the relatively low foreground gas content that makes it possible to detect absorption-lines weak enough that unseen components should not be saturated. Methods: Interstellar lines of H i, N i, O i, Si ii, P ii, Ar i, and Fe ii are detected. Column densities are derived directly from the observed line profiles except for H i, whose lines are contaminated by stellar absorption, thus needing the stellar continuum to be removed. We used the TLUSTY models to remove the stellar continuum and isolate the interstellar component. The best fit indicates that the dominant stellar population is B0. The observed far-UV flux agrees with an equivalent number of ~300 B0 stars. The fit of the interstellar H i line gives a column density of 1020.3±0.4 cm-2. Chemical abundances were then computed from the column densities using the dominant ionization stage in the neutral gas. Our abundances are compared to those measured from emission-line spectra in the optical, probing the ionized gas of the H ii regions. Results: Our results suggest that the neutral gas of Pox 36 is metal-deficient by a factor ~7 as compared to the ionized gas, and they agree with a metallicity of ≈1/35 Z_⊙. Elemental depletion is not problematic because of the low dust content along the selected lines of sight. In contrast, the ionized gas shows a clear depletion pattern, with iron being strongly depleted. Conclusions: The abundance discontinuity between the neutral and ionized phases

Calculation of effective impedance of polycrystals in weak magnetic fields

International Nuclear Information System (INIS)

Kaganova, I.M.

2006-01-01

We present results for the effective surface impedance tensor (EIT) of polycrystals of metals in a weak uniform magnetic field H. The frequency region corresponds to the region in which the local impedance boundary conditions are applicable. We suppose that the resistivity tensor ρ ik (H) of the single crystal grains out of which the polycrystal is composed, is known up to the terms of O(H 2 ). For polycrystals of metals of arbitrary symmetry, the elements of the EIT can be calculated to the same order in H, even if the tensor ρ ik (H) is strongly anisotropic. As examples, we write down the EIT of polycrystals of (i) cubic metals (ii) metals with ellipsoidal Fermi surfaces, and (iii) metals of tetragonal symmetry whose tensor ρ ik (0) is strongly anisotropic. Although polycrystals are metals that are isotropic on average, in the presence of a uniform magnetic field the structure of the EIT is not the same as the structure of the impedance tensor of an isotropic metal with a spherical Fermi surface. The results cannot be improved either by taking into account higher powers of H, or with respect to the anisotropy of the single crystal grains

A theoretical analysis of the weak shock waves propagating through a bubbly flow

International Nuclear Information System (INIS)

Jun, Gu Sik; Kim, Heuy Dong; Baek, Seung Cheol

2004-01-01

Two-phase flow of liquid and gas through pipe lines are frequently encountered in nuclear power plant or industrial facility. Pressure waves which can be generated by a valve operation or any other cause in pipe lines propagate through the two-phase flow, often leading to severe noise and vibration problems or fatigue failure of pipe line system. It is of practical importance to predict the propagation characteristics of the pressure waves for the safety design for the pipe line. In the present study, a theoretical analysis is performed to understand the propagation characteristics of a weak shock wave in a bubbly flow. A wave equation is developed using a small perturbation method to analyze the weak shock wave through a bubbly flow with comparably low void fractions. It is known that the elasticity of pipe and void fraction significantly affect the propagation speed of shock wave, but the frequency of relaxation oscillation which is generated behind the shock wave is not strongly influenced by the elasticity of pipe. The present analytical results are in close agreement with existing experimental data

A radio survey of weak T Tauri stars in Taurus-Auriga

International Nuclear Information System (INIS)

O'neal, D.; Feigelson, E.D.; Mathieu, R.D.; Myers, P.C.

1990-01-01

A multi-epoch 5 GHz survey of candidate or confirmed weak T Tauri stars in the Taurus-Auriga molecular cloud complex was conducted with the Very Large Array. The stars were chosen from those having detectable X-ray or chromospheric emission, and weak-emission-line pre-main-sequence stars found by other means. Snapshots of 99 VLA fields containing 119 candidate stars were obtained with a sensitivity of 0.7 mJy; most fields were observed on two or three dates. Nine radio sources coincident with cataloged stars were found. One may be an RS CVn binary system; the other eight are pre-main-sequence stars. Three of the detected stars - HD 283447, V410 Tau, and FK X-ray 1 - were previously known radio sources. Five new detections are Herbig's Anon 1, Hubble 4, HDE 283572, Elias 12, and HK Tau/c. At least five of the sources are variable, and no linear or circular polarization was found. Several lines of evidence suggest that the radio-detected weak T Tauri stars are quite young, perhaps younger on average than nondetected stars. 54 refs

On the Weak-Wind Problem in Massive Stars: X-Ray Spectra Reveal a Massive Hot Wind in mu Columbae

Science.gov (United States)

Huenemoerder, David P.; Oskinova, Lidia M.; Ignace, Richard; Waldron, Wayne L.; Todt, Helge; Hamaguchi, Kenji; Kitamoto, Shunji

2012-01-01

Mu Columbae is a prototypical weak-wind O star for which we have obtained a high-resolution X-ray spectrum with the Chandra LETG/ACIS instrument and a low-resolution spectrum with Suzaku. This allows us, for the first time, to investigate the role of X-rays on the wind structure in a bona fide weak-wind system and to determine whether there actually is a massive hot wind. The X-ray emission measure indicates that the outflow is an order of magnitude greater than that derived from UV lines and is commensurate with the nominal wind-luminosity relationship for O stars. Therefore, the "weak-wind problem"--identified from cool wind UV/optical spectra--is largely resolved by accounting for the hot wind seen in X-rays. From X-ray line profiles, Doppler shifts, and relative strengths, we find that this weak-wind star is typical of other late O dwarfs. The X-ray spectra do not suggest a magnetically confined plasma-the spectrum is soft and lines are broadened; Suzaku spectra confirm the lack of emission above 2 keV. Nor do the relative line shifts and widths suggest any wind decoupling by ions. The He-like triplets indicate that the bulk of the X-ray emission is formed rather close to the star, within five stellar radii. Our results challenge the idea that some OB stars are "weak-wind" stars that deviate from the standard wind-luminosity relationship. The wind is not weak, but it is hot and its bulk is only detectable in X-rays.

Propagation and attenuation of sound waves as well as spectrally resolved Rayleigh scattering in weakly ionized plasmas

International Nuclear Information System (INIS)

Kopainsky, J.

1975-01-01

In weakly ionized plasmas the scattering of electromagnetic waves on free electrons (Thompson scattering) can be neglected as compared with the scattering on bound electrons (Rayleigh scattering). If the scattering process can be described by a fluid dynamical model it is caused by sound waves which are generated or annihilated by the incident electromagnetic wave. The propagation of sound waves results in a shift of the scattered line whereas their absorption within the plasma produces the broadening of the scattered line. The theory of propagation of sound in weakly ionized plasmas is developed and extended to Rayleigh scattering. The results are applied to laser scattering in a weakly ionized hydrogen plasma. (Auth.)

Weak measurements and quantum weak values for NOON states

Science.gov (United States)

Rosales-Zárate, L.; Opanchuk, B.; Reid, M. D.

2018-03-01

Quantum weak values arise when the mean outcome of a weak measurement made on certain preselected and postselected quantum systems goes beyond the eigenvalue range for a quantum observable. Here, we propose how to determine quantum weak values for superpositions of states with a macroscopically or mesoscopically distinct mode number, that might be realized as two-mode Bose-Einstein condensate or photonic NOON states. Specifically, we give a model for a weak measurement of the Schwinger spin of a two-mode NOON state, for arbitrary N . The weak measurement arises from a nondestructive measurement of the two-mode occupation number difference, which for atomic NOON states might be realized via phase contrast imaging and the ac Stark effect using an optical meter prepared in a coherent state. The meter-system coupling results in an entangled cat-state. By subsequently evolving the system under the action of a nonlinear Josephson Hamiltonian, we show how postselection leads to quantum weak values, for arbitrary N . Since the weak measurement can be shown to be minimally invasive, the weak values provide a useful strategy for a Leggett-Garg test of N -scopic realism.

Immobilized poly-L-histidine for chelation of metal cations and metal oxyanions

International Nuclear Information System (INIS)

Malachowski, Lisa; Holcombe, James A.

2003-01-01

The biohomopolymer poly-L-histidine (PLHis) was immobilized onto controlled pore glass (CPG) and its metal binding capabilities evaluated through the use of a flow injection-flame atomic absorption system. The metal binding capability of PLHis-CPG was determined through the analysis of the generated breakthrough curves. The polymer likely coordinates cationic metals through the imidazole side chain (pK a ∼6) present on each histidine residue with both strong and weak binding sites for Cu 2+ , Cd 2+ , Co 2+ , and Ni 2+ . Weak to minimal binding was observed for Mn 2+ , Ca 2+ , Mg 2+ , Na + , and Cr 3+ . The bound metals are quantitatively released from the column with an acid strip. It has also been shown that the protonated imidazole side chain present in acidic solutions is capable of binding metal oxyanions such as chromates, arsenates, and selenites; although oxyanion binding currently exhibits interferences from competing anions in solution, such as sulfate and nitrate. The interference in oxyanion binding is less severe in the presence of chloride, phosphate, and acetate. PLHis-CPG exhibits a capacity of ∼30 μmol Cu 2+ /g CPG in neutral to basic conditions, and a capacity of ∼70 μmol Cr(VI)/g CPG, ∼4 μmol As(V)/g CPG, and ∼4 μmol Se(IV)/g CPG in acidic conditions

Inductive coupling between overhead power lines and nearby metallic pipelines. A neural network approach

Directory of Open Access Journals (Sweden)

Levente Czumbil

2015-12-01

Full Text Available The current paper presents an artificial intelligence based technique applied in the investigation of electromagnetic interference problems between high voltage power lines (HVPL and nearby underground metallic pipelines (MP. An artificial neural network (NN solution has been implemented by the authors to evaluate the inductive coupling between HVPL and MP for different constructive geometries of an electromagnetic interference problem considering a multi-layer soil structure. Obtained results are compared to solutions provided by a finite element method (FEM based analysis and considered as reference. The advantage of the proposed method yields in a simplified computation model compared to FEM, and implicitly a lower computational time.

Spectroscopic Comparison of Metal-rich RRab Stars of the Galactic Field with their Metal-poor Counterparts

Energy Technology Data Exchange (ETDEWEB)

Chadid, Merieme [Université Nice Sophia–Antipolis, Observatoire de la Côte dAzur, UMR 7293, Parc Valrose, F-06108, Nice Cedex 02 (France); Sneden, Christopher [Department of Astronomy and McDonald Observatory, The University of Texas, Austin, TX 78712 (United States); Preston, George W., E-mail: chadid@unice.fr, E-mail: chris@verdi.as.utexas.edu, E-mail: gwp@obs.carnegiescience.edu [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

2017-02-01

We investigate atmospheric properties of 35 stable RRab stars that possess the full ranges of period, light amplitude, and metal abundance found in Galactic RR Lyrae stars. Our results are derived from several thousand echelle spectra obtained over several years with the du Pont telescope of Las Campanas Observatory. Radial velocities of metal lines and the H α line were used to construct curves of radial velocity versus pulsation phase. From these we estimated radial velocity amplitudes for metal lines (formed near the photosphere) and H α Doppler cores (formed at small optical depths). We also measured H α emission fluxes when they appear during primary light rises. Spectra shifted to rest wavelengths, binned into small phase intervals, and co-added were used to perform model atmospheric and abundance analyses. The derived metallicities and those of some previous spectroscopic surveys were combined to produce a new calibration of the Layden abundance scale. We then divided our RRab sample into metal-rich (disk) and metal-poor (halo) groups at [Fe/H] = −1.0; the atmospheres of RRab families, so defined, differ with respect to (a) peak strength of H α emission flux, (b) H α radial velocity amplitude, (c) dynamical gravity, (d) stellar radius variation, (e) secondary acceleration during the photometric bump that precedes minimum light, and (f) duration of H α line-doubling. We also detected H α line-doubling during the “bump” in the metal-poor family, but not in the metal-rich one. Although all RRab probably are core helium-burning horizontal branch stars, the metal-rich group appears to be a species sui generis.

Hybrid Simulation of Supersonic Flow of Weakly Ionized Plasma along Open Field Magnetic Line Effect of Background Pressure

Science.gov (United States)

Laosunthara, Ampan; Akatsuka, Hiroshi

2016-09-01

In previous study, we experimentally examined physical properties of supersonic flow of weakly ionized expanding arc-jet plasma through an open magnetic field line (Bmax 0.16T). We found supersonic velocity of helium plasma up to Mach 3 and the space potential drop at the end of the magnets. To understand the plasma in numerical point of view, the flows of ion and neutral are treated by particle-based Direct Simulation Monte Carlo (DSMC) method, electron is treated as a fluid. The previous numerical study, we assumed 2 conditions. Ion and electron temperatures were the same (LTE condition). Ion and electron velocities were the same (current-free condition). We found that ion velocity decreased by collision with residual gas molecules (background pressure). We also found that space potential changing with background pressure. In other words, it was indicated that electric field exists and the current-free assumption is not proper. In this study, we add electron continuity and electron momentum equations to obtain electron velocity and space potential. We find that space potential changing with background pressure slightly. It is indicated that electron is essential to space potential formation than ion.

Testing weak form efficiency on the capital markets in Serbia

Directory of Open Access Journals (Sweden)

Kršikapa-Rašajski Jovana

2016-01-01

Full Text Available Weak-form efficient market hypothesis assumes that participants on the financial markets are not able to achieve above-average returns based on historical prices. In order to establish the presence of a weak-form market efficiency in the Serbian market, the analysis incorporates daily data of the two most prominent indices on the Belgrade Stock Exchange, BELEX 15 and BELEX LINE, since their inception until 31 December 2014. Results obtained by the analysis and testing indicate that the capital market in Serbia can not be considered sufficiently efficient, more precisely it indicates that postulates assumed by the weak-form market efficiency are not fully met. Taking into account that the capital market in Serbia is still underdeveloped, primarily because of the small volumes, turnover and types of securities which are traded on the market, as well as the fact that it is not sufficiently regulated and transparent, lack of investors is noticeable. Consequently, analysis presented in this paper indicates a weak sustainability of the efficient market hypothesis in Serbia.

MICROLENSING OF QUASAR BROAD EMISSION LINES: CONSTRAINTS ON BROAD LINE REGION SIZE

Energy Technology Data Exchange (ETDEWEB)

Guerras, E.; Mediavilla, E. [Instituto de Astrofisica de Canarias, Via Lactea S/N, La Laguna E-38200, Tenerife (Spain); Jimenez-Vicente, J. [Departamento de Fisica Teorica y del Cosmos, Universidad de Granada, Campus de Fuentenueva, E-18071 Granada (Spain); Kochanek, C. S. [Department of Astronomy and the Center for Cosmology and Astroparticle Physics, The Ohio State University, 4055 McPherson Lab, 140 West 18th Avenue, Columbus, OH 43221 (United States); Munoz, J. A. [Departamento de Astronomia y Astrofisica, Universidad de Valencia, E-46100 Burjassot, Valencia (Spain); Falco, E. [Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Motta, V. [Departamento de Fisica y Astronomia, Universidad de Valparaiso, Avda. Gran Bretana 1111, Valparaiso (Chile)

2013-02-20

We measure the differential microlensing of the broad emission lines between 18 quasar image pairs in 16 gravitational lenses. We find that the broad emission lines are in general weakly microlensed. The results show, at a modest level of confidence (1.8{sigma}), that high ionization lines such as C IV are more strongly microlensed than low ionization lines such as H{beta}, indicating that the high ionization line emission regions are more compact. If we statistically model the distribution of microlensing magnifications, we obtain estimates for the broad line region size of r{sub s} = 24{sup +22} {sub -15} and r{sub s} = 55{sup +150} {sub -35} lt-day (90% confidence) for the high and low ionization lines, respectively. When the samples are divided into higher and lower luminosity quasars, we find that the line emission regions of more luminous quasars are larger, with a slope consistent with the expected scaling from photoionization models. Our estimates also agree well with the results from local reveberation mapping studies.

Friction and solid-solid adhesion on complex metallic alloys

Science.gov (United States)

Dubois, Jean-Marie; Belin-Ferré, Esther

2014-01-01

The discovery in 1987 of stable quasicrystals in the Al–Cu–Fe system was soon exploited to patent specific coatings that showed reduced friction in ambient air against hard antagonists. Henceforth, it was possible to develop a number of applications, potential or commercially exploited to date, that will be alluded to in this topical review. A deeper understanding of the characteristics of complex metallic alloys (CMAs) may explain why material made of metals like Al, Cu and Fe offers reduced friction; low solid–solid adhesion came later. It is linked to the surface energy being significantly lower on those materials, in which translational symmetry has become a weak property, that is determined by the depth of the pseudo-gap at the Fermi energy. As a result, friction is anisotropic in CMAs that builds up according to the translation symmetry along one direction, but is aperiodic along the other two directions. A review is given in this article of the most salient data found along these lines during the past two decades or so. PMID:27877675

STAR FORMATION IN SELF-GRAVITATING DISKS IN ACTIVE GALACTIC NUCLEI. II. EPISODIC FORMATION OF BROAD-LINE REGIONS

International Nuclear Information System (INIS)

WangJianmin; Du Pu; Ge Junqiang; Hu Chen; Baldwin, Jack A.; Ferland, Gary J.

2012-01-01

compose the high-ionization line regions whereas the metal-poor clouds are in low-ionization line (LIL) regions. Since metal-rich clouds are optically thin, they will be blown away by radiation pressure, forming the observed outflows. The outflowing clouds could set up a metallicity correlation between the BLRs and narrow-line regions. The LIL regions are episodic due to the mass cycle of clouds with the CAS in response to continuous injection by the SF disk, giving rise to different types of AGNs. Based on Sloan Digital Sky Survey quasar spectra, we identify a spectral sequence in light of emission-line equivalent width from phase I to IV. A key phase in the episodic appearance of the BLRs is bright type II AGNs with no or only weak BLRs, contrary to the popular picture in which the absence of a BLR is due to a low accretion rate. We discuss observational implications and tests of the theoretical predictions of this model.

Theory of hydrogen chemisorption on metals

International Nuclear Information System (INIS)

Brenig, W.

1975-01-01

A theory of hydrogen chemisorption on metals is presented. Green's function is derived taking into account the coupling strength between metal and chemisorbed atom and the strength of the interatomic Coulomb repulsion, allowing the calculation of the local density of states at the adatom, especially for the limiting cases of strong and weak coupling

Weak interactions

International Nuclear Information System (INIS)

Ogava, S.; Savada, S.; Nakagava, M.

1983-01-01

The problem of the use of weak interaction laws to study models of elementary particles is discussed. The most typical examples of weak interaction is beta-decay of nucleons and muons. Beta-interaction is presented by quark currents in the form of universal interaction of the V-A type. Universality of weak interactions is well confirmed using as examples e- and μ-channels of pion decay. Hypothesis on partial preservation of axial current is applicable to the analysis of processes with pion participation. In the framework of the model with four flavours lepton decays of hadrons are considered. Weak interaction without lepton participation are also considered. Properties of neutral currents are described briefly

Topic Detection Based on Weak Tie Analysis: A Case Study of LIS Research

Directory of Open Access Journals (Sweden)

Ling Wei

2016-11-01

Full Text Available Purpose: Based on the weak tie theory, this paper proposes a series of connection indicators of weak tie subnets and weak tie nodes to detect research topics, recognize their connections, and understand their evolution. Design/methodology/approach: First, keywords are extracted from article titles and preprocessed. Second, high-frequency keywords are selected to generate weak tie co-occurrence networks. By removing the internal lines of clustered sub-topic networks, we focus on the analysis of weak tie subnets' composition and functions and the weak tie nodes' roles. Findings: The research topics' clusters and themes changed yearly; the subnets clustered with technique-related and methodology-related topics have been the core, important subnets for years; while close subnets are highly independent, research topics are generally concentrated and most topics are application-related; the roles and functions of nodes and weak ties are diversified. Research limitations: The parameter values are somewhat inconsistent; the weak tie subnets and nodes are classified based on empirical observations, and the conclusions are not verified or compared to other methods. Practical implications: The research is valuable for detecting important research topics as well as their roles, interrelations, and evolution trends. Originality/value: To contribute to the strength of weak tie theory, the research translates weak and strong ties concepts to co-occurrence strength, and analyzes weak ties' functions. Also, the research proposes a quantitative method to classify and measure the topics' clusters and nodes.

Weakly clopen functions

International Nuclear Information System (INIS)

Son, Mi Jung; Park, Jin Han; Lim, Ki Moon

2007-01-01

We introduce a new class of functions called weakly clopen function which includes the class of almost clopen functions due to Ekici [Ekici E. Generalization of perfectly continuous, regular set-connected and clopen functions. Acta Math Hungar 2005;107:193-206] and is included in the class of weakly continuous functions due to Levine [Levine N. A decomposition of continuity in topological spaces. Am Math Mon 1961;68:44-6]. Some characterizations and several properties concerning weakly clopenness are obtained. Furthermore, relationships among weak clopenness, almost clopenness, clopenness and weak continuity are investigated

EXAMINATION OF THE MASS-DEPENDENT Li DEPLETION HYPOTHESIS BY THE Li ABUNDANCES OF THE VERY METAL-POOR DOUBLE-LINED SPECTROSCOPIC BINARY G166-45

International Nuclear Information System (INIS)

Aoki, Wako; Ito, Hiroko; Tajitsu, Akito

2012-01-01

The Li abundances of the two components of the very metal-poor ([Fe/H] –2.5) double-lined spectroscopic binary G166-45 (BD+26°2606) are determined separately based on high-resolution spectra obtained with the Subaru Telescope High Dispersion Spectrograph and its image slicer. From the photometric colors and the mass ratio, the effective temperatures of the primary and secondary components are estimated to be 6350 ± 100 K and 5830 ± 170 K, respectively. The Li abundance of the primary (A(Li) = 2.23) agrees well with the Spite plateau value, while that of the secondary is slightly lower (A(Li) = 2.11). Such a discrepancy of the Li abundances between the two components is previously found in the extremely metal-poor, double-lined spectroscopic binary CS 22876-032; however, the discrepancy in G166-45 is much smaller. The results agree with the trends found for Li abundance as a function of effective temperature (and of stellar mass) of main-sequence stars with –3.0 eff ∼ 5800 K is not particularly large in this metallicity range. The significant Li depletion found in CS 22876-032B is a phenomenon only found in the lowest metallicity range ([Fe/H] < –3).

Weak measurement from the electron displacement current: new path for applications

International Nuclear Information System (INIS)

Marian, D; Colomés, E; Oriols, X; Zanghì, N

2015-01-01

The interest on weak measurements is rapidly growing during the last years as a unique tool to better understand and predict new quantum phenomena. Up to now many theoretical and experimental weak-measurement techniques deal with (relativistic) photons or cold atoms, but there is much less investigation on (non-relativistic) electrons in up-to-date electronics technologies. We propose a way to perform weak measurements in nanoelectronic devices through the measurement of the total current (particle plus displacement component) in such devices. We study the interaction between an electron in the active region of a electron device with a metal surface working as a sensing electrode by means of the (Bohmian) conditional wave function. We perform numerical (Monte Carlo) simulations to reconstruct the Bohmian trajectories in the iconic double slit experiment. This work opens new paths for understanding the quantum properties of an electronic system as well as for exploring new quantum engineering applications in solid state physics. (paper)

Metallicities of Emission-Line Galaxies from HST ACS PEARS and HST WFC3 ERS Grism Spectroscopy at 0.6 is less than z is less than 2.4

Science.gov (United States)

Xia, Lifang; Malhotra, Sangetta; Rhoads, James; Pirzkal, Nor; Straughn, Amber; Finkelstein, Steven; Cohen, Seth; Kuntschner, Harald; Walsh, Jeremy; Windhorst, Rogier A.;

Vacuum evaporation of pure metals

OpenAIRE

Safarian, Jafar; Engh, Thorvald Abel

2013-01-01

Theories on the evaporation of pure substances are reviewed and applied to study vacuum evaporation of pure metals. It is shown that there is good agreement between different theories for weak evaporation, whereas there are differences under intensive evaporation conditions. For weak evaporation, the evaporation coefficient in Hertz-Knudsen equation is 1.66. Vapor velocity as a function of the pressure is calculated applying several theories. If a condensing surface is less than one collision...

Weak value controversy

Science.gov (United States)

Vaidman, L.

2017-10-01

Recent controversy regarding the meaning and usefulness of weak values is reviewed. It is argued that in spite of recent statistical arguments by Ferrie and Combes, experiments with anomalous weak values provide useful amplification techniques for precision measurements of small effects in many realistic situations. The statistical nature of weak values is questioned. Although measuring weak values requires an ensemble, it is argued that the weak value, similarly to an eigenvalue, is a property of a single pre- and post-selected quantum system. This article is part of the themed issue `Second quantum revolution: foundational questions'.

On-line adaptive line frequency noise cancellation from a nuclear power measuring channel

Directory of Open Access Journals (Sweden)

Qadir Javed

2011-01-01

Full Text Available On-line software for adaptively canceling 50 Hz line frequency noise has been designed and tested at Pakistan Research Reactor 1. Line frequency noise causes much problem in weak signals acquisition. Sometimes this noise is so dominant that original signal is totally corrupted. Although notch filter can be used for eliminating this noise, but if signal of interest is in close vicinity of 50 Hz, then original signal is also attenuated and hence overall performance is degraded. Adaptive noise removal is a technique which could be employed for removing line frequency without degrading the desired signal. In this paper line frequency noise has been eliminated on-line from a nuclear power measuring channel. The adaptive LMS algorithm has been used to cancel 50 Hz noise. The algorithm has been implemented in labVIEW with NI 6024 data acquisition card. The quality of the acquired signal has been improved much as can be seen in experimental results.

Dislocation Line Tensions in the Noble Metals, the Alkali Metals and beta-Brass

Energy Technology Data Exchange (ETDEWEB)

Pettersson, B; Malen, K

1971-06-15

The line tension for a straight partial dislocation which can produce the necessary slip for a martensitic phase transformation of the bcc-fcc or bcc-hcp type has been calculated in ordered 6-brass and in Li, Na and K. Also the line tension for a Shockley partial dislocation in Cu, Ag and Au has been calculated. Negative line tension is found for certain dislocation directions, and the possible influence of this on the stability of a stacking fault bounded by these partials is discussed

On-line sample-pre-treatment schemes for trace-level determinations of metals by coupling flow injection or sequential injection with ICP-MS

DEFF Research Database (Denmark)

Wang, Jianhua; Hansen, Elo Harald

2003-01-01

a polytetrafluoroethylene (PTFE) knotted reactor (KR), solvent extraction-back extraction and hydride/vapor generation. It also addresses a novel, robust approach, whereby the protocol of SI-LOV-bead injection (BI) on-line separation and pre-concentration of ultra-trace levels of metals by a renewable microcolumn...

Heterotic line bundle models on elliptically fibered Calabi-Yau three-folds

Science.gov (United States)

Braun, Andreas P.; Brodie, Callum R.; Lukas, Andre

2018-04-01

We analyze heterotic line bundle models on elliptically fibered Calabi-Yau three-folds over weak Fano bases. In order to facilitate Wilson line breaking to the standard model group, we focus on elliptically fibered three-folds with a second section and a freely-acting involution. Specifically, we consider toric weak Fano surfaces as base manifolds and identify six such manifolds with the required properties. The requisite mathematical tools for the construction of line bundle models on these spaces, including the calculation of line bundle cohomology, are developed. A computer scan leads to more than 400 line bundle models with the right number of families and an SU(5) GUT group which could descend to standard-like models after taking the ℤ2 quotient. A common and surprising feature of these models is the presence of a large number of vector-like states.

First Time Rapid and Accurate Detection of Massive Number of Metal Absorption Lines in the Early Universe Using Deep Neural Network

Science.gov (United States)

Zhao, Yinan; Ge, Jian; Yuan, Xiaoyong; Li, Xiaolin; Zhao, Tiffany; Wang, Cindy

2018-01-01

Metal absorption line systems in the distant quasar spectra have been used as one of the most powerful tools to probe gas content in the early Universe. The MgII λλ 2796, 2803 doublet is one of the most popular metal absorption lines and has been used to trace gas and global star formation at redshifts between ~0.5 to 2.5. In the past, machine learning algorithms have been used to detect absorption lines systems in the large sky survey, such as Principle Component Analysis, Gaussian Process and decision tree, but the overall detection process is not only complicated, but also time consuming. It usually takes a few months to go through the entire quasar spectral dataset from each of the Sloan Digital Sky Survey (SDSS) data release. In this work, we applied the deep neural network, or “ deep learning” algorithms, in the most recently SDSS DR14 quasar spectra and were able to randomly search 20000 quasar spectra and detect 2887 strong Mg II absorption features in just 9 seconds. Our detection algorithms were verified with previously released DR12 and DR7 data and published Mg II catalog and the detection accuracy is 90%. This is the first time that deep neural network has demonstrated its promising power in both speed and accuracy in replacing tedious, repetitive human work in searching for narrow absorption patterns in a big dataset. We will present our detection algorithms and also statistical results of the newly detected Mg II absorption lines.

Pressure-induced organic topological nodal-line semimetal in the three-dimensional molecular crystal Pd (dddt) 2

Science.gov (United States)

Liu, Zhao; Wang, Haidi; Wang, Z. F.; Yang, Jinlong; Liu, Feng

2018-04-01

The nodal-line semimetal represents a class of topological materials characterized with highest band degeneracy. It is usually found in inorganic materials of high crystal symmetry or a minimum symmetry of inversion aided with accidental band degeneracy [Phys. Rev. Lett. 118, 176402 (2017), 10.1103/PhysRevLett.118.176402]. Based on first-principles band structure, Wannier charge center, and topological surface state calculations, here we predict a pressure-induced topological nodal-line semimetal in the absence of spin-orbit coupling (SOC) in the synthesized single-component 3D molecular crystal Pd (dddt) 2 . We show a Γ -centered single nodal line undulating within a narrow energy window across the Fermi level. This intriguing nodal line is generated by pressure-induced accidental band degeneracy, without protection from any crystal symmetry. When SOC is included, the fourfold degenerated nodal line is gapped and Pd (dddt) 2 becomes a strong 3D topological metal with an Z2 index of (1;000). However, the tiny SOC gap makes it still possible to detect the nodal-line properties experimentally. Our findings afford an attractive route for designing and realizing topological states in 3D molecular crystals, as they are weakly bonded through van der Waals forces with a low crystal symmetry so that their electronic structures can be easily tuned by pressure.

Fundamental parameters of He-weak and He-strong stars

Science.gov (United States)

Cidale, L. S.; Arias, M. L.; Torres, A. F.; Zorec, J.; Frémat, Y.; Cruzado, A.

2007-06-01

Context: He-weak and He-strong stars are chemically peculiar AB objects whose He lines are anomalously weak or strong for their MK spectral type. The determination of fundamental parameters for these stars is often more complex than for normal stars due to their abundance anomalies. Aims: We discuss the determination of fundamental parameters: effective temperature, surface gravity, and visual and bolometric absolute magnitudes of He-weak and He-strong stars. We compare our values with those derived independently from methods based on photometry and model fitting. Methods: We carried out low resolution spectroscopic observations in the wavelength range 3400-4700 Å of 20 He-weak and 8 He-strong stars to determine their fundamental parameters by means of the Divan-Chalonge-Barbier (BCD) spectrophotometric system. This system is based on the measurement of the continuum energy distribution around the Balmer discontinuity (BD). For a few He-weak stars we also estimate the effective temperatures and the angular diameters by integrating absolute fluxes observed over a wide spectral range. Non-LTE model calculations are carried out to study the influence of the He/H abundance ratio on the emergent radiation of He-strong stars and on their T_eff determination. Results: We find that the effective temperatures, surface gravities and bolometric absolute magnitudes of He-weak stars estimated with the BCD system and the integrated flux method are in good agreement between each other, and they also agree with previous determinations based on several different methods. The mean discrepancy between the visual absolute magnitudes derived using the hipparcos parallaxes and the BCD values is on average ±0.3 mag for He-weak stars, while it is ±0.5 mag for He-strong stars. For He-strong stars, we note that the BCD calibration, based on stars in the solar environment, leads to overestimated values of T_eff. By means of model atmosphere calculations with enhanced He/H abundance ratios

Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

Science.gov (United States)

Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

2013-01-01

A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

The Problem of Weak Governments and Weak Societies in Eastern Europe

Directory of Open Access Journals (Sweden)

Marko Grdešić

2008-01-01

Full Text Available This paper argues that, for Eastern Europe, the simultaneous presence of weak governments and weak societies is a crucial obstacle which must be faced by analysts and reformers. The understanding of other normatively significant processes will be deficient without a consciousness-raising deliberation on this problem and its implications. This paper seeks to articulate the “relational” approach to state and society. In addition, the paper lays out a typology of possible patterns of relationship between state and society, dependent on whether the state is weak or strong and whether society is weak or strong. Comparative data are presented in order to provide an empirical support for the theses. Finally, the paper outlines two reform approaches which could enable breaking the vicious circle emerging in the context of weak governments and weak societies.

The Weak Gravity Conjecture and the axionic black hole paradox

Science.gov (United States)

Hebecker, Arthur; Soler, Pablo

2017-09-01

In theories with a perturbatively massless 2-form (dual to an axion), a paradox may arise in the process of black hole evaporation. Schwarzschild black holes can support a non-trivial Wilson-line-type field, the integral of the 2-form around their horizon. After such an `axionic black hole' evaporates, the Wilson line must be supported by the corresponding 3-form field strength in the region formerly occupied by the black hole. In the limit of small axion decay-constant f, the energy required for this field configuration is too large. Thus, energy cannot be conserved in the process of black hole evaporation. The natural resolution of this paradox is through the presence of light strings, which allow the black hole to "shed" its axionic hair sufficiently early. This gives rise to a new Weak-Gravity-type argument in the 2-form context: small coupling, in this case f , enforces the presence of light strings or a low cutoff. We also discuss how this argument may be modified in situations where the weak coupling regime is achieved in the low-energy effective theory through an appropriate gauging of a model with a vector field and two 2-forms.

Electro-weak theory

International Nuclear Information System (INIS)

Deshpande, N.G.

1980-01-01

By electro-weak theory is meant the unified field theory that describes both weak and electro-magnetic interactions. The development of a unified electro-weak theory is certainly the most dramatic achievement in theoretical physics to occur in the second half of this century. It puts weak interactions on the same sound theoretical footing as quantum elecrodynamics. Many theorists have contributed to this development, which culminated in the works of Glashow, Weinberg and Salam, who were jointly awarded the 1979 Nobel Prize in physics. Some of the important ideas that contributed to this development are the theory of beta decay formulated by Fermi, Parity violation suggested by Lee and Yang, and incorporated into immensely successful V-A theory of weak interactions by Sudarshan and Marshak. At the same time ideas of gauge invariance were applied to weak interaction by Schwinger, Bludman and Glashow. Weinberg and Salam then went one step further and wrote a theory that is renormalizable, i.e., all higher order corrections are finite, no mean feat for a quantum field theory. The theory had to await the development of the quark model of hadrons for its completion. A description of the electro-weak theory is given

Assessment and genetic analysis of heavy metal content in rice grain using an Oryza sativa × O. rufipogon backcross inbred line population.

Science.gov (United States)

Huang, De-Run; Fan, Ye-Yang; Hu, Biao-Lin; Xiao, Ye-Qing; Chen, Da-Zhou; Zhuang, Jie-Yun

2018-03-01

Heavy metal accumulation in rice is a growing concern for public health. Backcross inbred lines derived from an interspecific cross of Oryza sativa × O. rufipogon were grown in two distinct ecological locations (Hangzhou and Lingshui, China). The objective of this study was to characterise the contents of heavy metal in rice grains, and to identify quantitative trait loci (QTLs) for heavy metal contents. The contents of Ni, As, Pb, Cr and Hg in milled rice showed a significant decline as compared with those in brown rice, whereas the content of Cd showed little change. The concentration of heavy metal in rice grain varied greatly between the two environments. A total of 24 QTLs responsible for heavy metal contents were detected, including two for both the brown and milled rice, 13 for brown rice only, and nine for milled rice only. All the QTLs except two had the enhancing alleles derived from O. rufipogon. Sixteen QTLs were clustered in six chromosomal regions. Environmental variation plays an important role in the heavy metal contents in rice grain. QTLs detected in this study might be useful for breeding rice varieties with low heavy metal content. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Weak decays

International Nuclear Information System (INIS)

Wojcicki, S.

1978-11-01

Lectures are given on weak decays from a phenomenological point of view, emphasizing new results and ideas and the relation of recent results to the new standard theoretical model. The general framework within which the weak decay is viewed and relevant fundamental questions, weak decays of noncharmed hadrons, decays of muons and the tau, and the decays of charmed particles are covered. Limitation is made to the discussion of those topics that either have received recent experimental attention or are relevant to the new physics. (JFP) 178 references

Effective photons in weakly absorptive dielectric media and the Beer–Lambert–Bouguer law

International Nuclear Information System (INIS)

Judge, A C; Brownless, J S; Martijn de Sterke, C; Bhat, N A R; Sipe, J E; Steel, M J

2014-01-01

We derive effective photon modes that facilitate an intuitive and convenient picture of photon dynamics in a structured Kramers–Kronig dielectric in the limit of weak absorption. Each mode is associated with a mode field distribution that includes the effects of both material and structural dispersion, and an effective line-width that determines the temporal decay rate of the photon. These results are then applied to obtain an expression for the Beer–Lambert–Bouguer law absorption coefficient for unidirectional propagation in structured media consisting of dispersive, weakly absorptive dielectric materials

Weak currents

International Nuclear Information System (INIS)

Leite Lopes, J.

1976-01-01

A survey of the fundamental ideas on weak currents such as CVC and PCAC and a presentation of the Cabibbo current and the neutral weak currents according to the Salam-Weinberg model and the Glashow-Iliopoulos-Miami model are given [fr

Line identification studies using traditional techniques and wavelength coincidence statistics

International Nuclear Information System (INIS)

Cowley, C.R.; Adelman, S.J.

1990-01-01

Traditional line identification techniques result in the assignment of individual lines to an atomic or ionic species. These methods may be supplemented by wavelength coincidence statistics (WCS). The strength and weakness of these methods are discussed using spectra of a number of normal and peculiar B and A stars that have been studied independently by both methods. The present results support the overall findings of some earlier studies. WCS would be most useful in a first survey, before traditional methods have been applied. WCS can quickly make a global search for all species and in this way may enable identifications of an unexpected spectrum that could easily be omitted entirely from a traditional study. This is illustrated by O I. WCS is a subject to well known weakness of any statistical technique, for example, a predictable number of spurious results are to be expected. The danger of small number statistics are illustrated. WCS is at its best relative to traditional methods in finding a line-rich atomic species that is only weakly present in a complicated stellar spectrum

Runs 800, 813, 842 and physics runs from 18.1.77 to 21.5.77, Development of a new set-up for working line measurements including a Fast Fourier Transform Spectrum Analyser and using weak beam excitiation with broad-band noise

CERN Document Server

Borer, J

1977-01-01

Runs 800, 813, 842 and physics runs from 18.1.77 to 21.5.77, Development of a new set-up for working line measurements including a Fast Fourier Transform Spectrum Analyser and using weak beam excitiation with broad-band noise

An extreme Fe II emitter the narrow line quasar PHL 1092

CERN Document Server

Bergeron, J

1980-01-01

A search for Fe II emission in a sample of radio-quiet quasars has revealed the outstanding properties of PHL 1092. Intense Fe II lines dominate the entire spectrum, and the Fe II UV multiplets are nearly as strong as the optical ones. In contrast the extreme weakness of the Balmer and Mg II lines is striking. For the first time, Fe I lines are identified in an extra-galactic object. The lines are narrow, with a FWHM of 1300 km s/sup -1/. The presence of Fe II UV lines and Fe I lines from the ground state requires moderate column densities. However Fe/sup 0/ can exist only in a region completely shielded from the UV continuum. The weakness of Mg II and H beta relative to Fe II lines is best explained by their thermalization. The emitting region is of high electron density n/sub e/ approximately=10/sup 12/ cm/sup -3/, low temperature T approximately=10000K, and has an optical depth in the Fe II UV lines tau /sub UV/ approximately=10/sup 3/-10/sup 4/. It is speculated that for higher densities all the lines wou...

Evidence of a Bottom-heavy Initial Mass Function in Massive Early-type Galaxies from Near-infrared Metal Lines

Science.gov (United States)

Lagattuta, David J.; Mould, Jeremy R.; Forbes, Duncan A.; Monson, Andrew J.; Pastorello, Nicola; Persson, S. Eric

2017-09-01

We present new evidence for a variable stellar initial mass function (IMF) in massive early-type galaxies, using high-resolution, near-infrared spectroscopy from the Folded-port InfraRed Echellette spectrograph (FIRE) on the Magellan Baade Telescope at Las Campanas Observatory. In this pilot study, we observe several gravity-sensitive metal lines between 1.1 and 1.3 μm in eight highly luminous (L˜ 10{L}* ) nearby galaxies. Thanks to the broad wavelength coverage of FIRE, we are also able to observe the Ca II triplet feature, which helps with our analysis. After measuring the equivalent widths (EWs) of these lines, we notice mild to moderate trends between EW and central velocity dispersion (σ), with some species (K I, Na I, Mn I) showing a positive EW-σ correlation and others (Mg I, Ca II, Fe I) a negative one. To minimize the effects of metallicity, we measure the ratio R = [EW(K I)/EW(Mg I)], finding a significant systematic increase in this ratio with respect to σ. We then probe for variations in the IMF by comparing the measured line ratios to the values expected in several IMF models. Overall, we find that low-mass galaxies (σ ˜ 100 km s-1) favor a Chabrier IMF, while high-mass galaxies (σ ˜ 350 km s-1) are better described with a steeper (dwarf-rich) IMF slope. While we note that our galaxy sample is small and may suffer from selection effects, these initial results are still promising. A larger sample of galaxies will therefore provide an even clearer picture of IMF trends in this regime. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Homological properties of modules with finite weak injective and weak flat dimensions

OpenAIRE

Zhao, Tiwei

2017-01-01

In this paper, we define a class of relative derived functors in terms of left or right weak flat resolutions to compute the weak flat dimension of modules. Moreover, we investigate two classes of modules larger than that of weak injective and weak flat modules, study the existence of covers and preenvelopes, and give some applications.

Direct n.c.a. radioiodination of weakly activated arenes using metal salts

OpenAIRE

Mennicke, E.; Holschbach, M.; Coenen, H. H.

2000-01-01

The direct electrophilic no-carrier-added (n.c.a.) aromatic radioiodination was examined using various metal salts in trifluoroacetic acid (TFA) as in situ oxidation agents. Two different types of metal salts were used comprising TFA-soluble (Pb(CH3CO2)(4), Mn(CH3CO2)(3), KMnO4, Tl(CF3CO2)(3), AgCF3SO3) and TFA-insoluble (Ce(CF3SO3)(4), RuCl3, FeBr3, K2Cr2O7) salts. Optimization of both labelling systems has been performed using Pb(CH3CO2)(4), Ce(CF3SO3)(4) and benzene as a model substrate. A...

The Little Cub: Discovery of an Extremely Metal-poor Star-forming Galaxy in the Local Universe

Energy Technology Data Exchange (ETDEWEB)

Hsyu, Tiffany; Prochaska, J. Xavier; Bolte, Michael [Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95060 (United States); Cooke, Ryan J. [Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)

2017-08-20

We report the discovery of the Little Cub, an extremely metal-poor star-forming galaxy in the local universe, found in the constellation Ursa Major (a.k.a. the Great Bear). We first identified the Little Cub as a candidate metal-poor galaxy based on its Sloan Digital Sky Survey photometric colors, combined with spectroscopy using the Kast spectrograph on the Shane 3 m telescope at Lick Observatory. In this Letter, we present high-quality spectroscopic data taken with the Low Resolution Imaging Spectrometer at Keck Observatory, which confirm the extremely metal-poor nature of this galaxy. Based on the weak [O iii] λ 4363 Å emission line, we estimate a direct oxygen abundance of 12 + log(O/H) = 7.13 ± 0.08, making the Little Cub one of the lowest-metallicity star-forming galaxies currently known in the local universe. The Little Cub appears to be a companion of the spiral galaxy NGC 3359 and shows evidence of gas stripping. We may therefore be witnessing the quenching of a near-pristine galaxy as it makes its first passage about a Milky Way–like galaxy.

The Little Cub: Discovery of an Extremely Metal-poor Star-forming Galaxy in the Local Universe

Science.gov (United States)

Hsyu, Tiffany; Cooke, Ryan J.; Prochaska, J. Xavier; Bolte, Michael

2017-08-01

We report the discovery of the Little Cub, an extremely metal-poor star-forming galaxy in the local universe, found in the constellation Ursa Major (a.k.a. the Great Bear). We first identified the Little Cub as a candidate metal-poor galaxy based on its Sloan Digital Sky Survey photometric colors, combined with spectroscopy using the Kast spectrograph on the Shane 3 m telescope at Lick Observatory. In this Letter, we present high-quality spectroscopic data taken with the Low Resolution Imaging Spectrometer at Keck Observatory, which confirm the extremely metal-poor nature of this galaxy. Based on the weak [O III] λ4363 Å emission line, we estimate a direct oxygen abundance of 12 + log(O/H) = 7.13 ± 0.08, making the Little Cub one of the lowest-metallicity star-forming galaxies currently known in the local universe. The Little Cub appears to be a companion of the spiral galaxy NGC 3359 and shows evidence of gas stripping. We may therefore be witnessing the quenching of a near-pristine galaxy as it makes its first passage about a Milky Way-like galaxy.

The Little Cub: Discovery of an Extremely Metal-poor Star-forming Galaxy in the Local Universe

International Nuclear Information System (INIS)

Hsyu, Tiffany; Prochaska, J. Xavier; Bolte, Michael; Cooke, Ryan J.

2017-01-01

We report the discovery of the Little Cub, an extremely metal-poor star-forming galaxy in the local universe, found in the constellation Ursa Major (a.k.a. the Great Bear). We first identified the Little Cub as a candidate metal-poor galaxy based on its Sloan Digital Sky Survey photometric colors, combined with spectroscopy using the Kast spectrograph on the Shane 3 m telescope at Lick Observatory. In this Letter, we present high-quality spectroscopic data taken with the Low Resolution Imaging Spectrometer at Keck Observatory, which confirm the extremely metal-poor nature of this galaxy. Based on the weak [O iii] λ 4363 Å emission line, we estimate a direct oxygen abundance of 12 + log(O/H) = 7.13 ± 0.08, making the Little Cub one of the lowest-metallicity star-forming galaxies currently known in the local universe. The Little Cub appears to be a companion of the spiral galaxy NGC 3359 and shows evidence of gas stripping. We may therefore be witnessing the quenching of a near-pristine galaxy as it makes its first passage about a Milky Way–like galaxy.

A new kind of metal detector based on chaotic oscillator

Science.gov (United States)

Hu, Wenjing

2017-12-01

The sensitivity of a metal detector greatly depends on the identification ability to weak signals from the probe. In order to improve the sensitivity of metal detectors, this paper applies the Duffing chaotic oscillator to metal detectors based on its characteristic which is very sensitive to weak periodic signals. To make a suitable Duffing system for detectors, this paper computes two Lyapunov characteristics exponents of the Duffing oscillator, which help to obtain the threshold of the Duffing system in the critical state accurately and give quantitative criteria for chaos. Meanwhile, a corresponding simulation model of the chaotic oscillator is made by the Simulink tool box of Matlab. Simulation results shows that Duffing oscillator is very sensitive to sinusoidal signals in high frequency cases. And experimental results show that the measurable diameter of metal particles is about 1.5mm. It indicates that this new method can feasibly and effectively improve the metal detector sensitivity.

Argon line broadening by neutral atoms and application to the measurement of oscillator strengths of AI resonance lines

International Nuclear Information System (INIS)

Vallee, O.; Ranson, P.; Chapelle, J.

1977-01-01

AI line broadening was studied from collisions between neutral argon atoms (3p 5 4p-3p 5 4s transitions) in a weakly ionised plasma jet (neutral atoms temperature T 0 approximately 4000K, electrons temperature Tsub(e) approximately 6000K, electronic density Nsub(e) 15 cm -3 , ionisation rate α -4 , and pressure range from 1 to 3 kg/cm 2 ). A satisfactory description of Van der Waals broadened lines is obtained by means of a Lennard-Jones potential. Measurement of line widths whose corresponding transitions occur on resonant levels, gives with relatively good accuracy the oscillator strength of the argon resonance lines [fr

Liquid metals. Coexistence line, critical parameters, compressibility

International Nuclear Information System (INIS)

Filippov, L.P.

1986-01-01

Formulae to calculate four characteristic parameters of liquid metals (density, compressibility, critical temperature and individual parameter) according to four initial data are obtained: two values of vapor density and two values of vapor pressure. Comparison between experimental and calculation results are presented for liquid Cs, Na, Li, K, Rb

Engineering metal (hydr)oxide sorbents for removal of arsenate and similar weak-acid oxyanion contaminants: A critical review with emphasis on factors governing sorption processes.

Science.gov (United States)

Hristovski, Kiril D; Markovski, Jasmina

2017-11-15

To create an integrative foundation for engineering of the next generation inexpensive sorbent systems, this critical review addresses the existing knowledge gap in factor/performance relationships between weak-acid oxyanion contaminants and metal (hydr)oxide sorbents. In-depth understanding of fundamental thermodynamics and kinetics mechanisms, material fabrication, and analytical and characterization techniques, is necessary to engineer sorbent that exhibit high capacity, selectivity, stability, durability and mass transport of contaminants under a wide range of operating and water matrix conditions requirements. From the perspective of thermodynamics and kinetics, this critical review examines the factors affecting sorbent performances and analyzes the existing research to elucidate future directions aimed at developing novel sorbents for removal of weak-acid oxyanion contaminants from water. Only sorbents that allow construction of simple and inexpensive water treatment systems adapted to overcome fiscal and technological barriers burdening small communities could pave the road for providing inexpensive potable water to millions of people. Novel sorbents, which exhibit (1) poor performances in realistic operating and water matrix conditions and/or (2) do not comply with the purely driven economics factors of production scalability or cost expectations, are predestined to never be commercialized. Copyright © 2017 Elsevier B.V. All rights reserved.

Surfactant-thermal method to prepare two new cobalt metal-organic frameworks

Energy Technology Data Exchange (ETDEWEB)

Yu, Xianglin [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430074 (China); Toh, Yong Siang [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Zhao, Jun [College of Materials and Chemical Engineering, Hubei Provincial Collaborative Innovation Center for New Energy Microgrid, China Three Gorges University, Yichang 443002 (China); Nie, Lina [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Ye, Kaiqi; Wang, Yue [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 (China); Li, Dongsheng [College of Materials and Chemical Engineering, Hubei Provincial Collaborative Innovation Center for New Energy Microgrid, China Three Gorges University, Yichang 443002 (China); Zhang, Qichun, E-mail: qczhang@ntu.edu.sg [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

2015-12-15

Employing surfactants as reaction media, two new metal-organic frameworks (MOFs):(HTEA){sub 3}[Co{sub 3}(BTC){sub 3}] (NTU-Z33) and (HTEA)[Co{sub 3}(HBTC){sub 2}(BTC)] (NTU-Z34) (H{sub 3}BTC=1,3,5-benzenetricarboxylic acid, TEA=trimethylamine, and NTU=Nanyang Technological University), have been successfully synthesized and fully characterized. Note that NTU-Z33 has an unusual trimeric [Co{sub 3}(COO){sub 9}] secondary building unit (SBU). Magnetic characterization suggests that both compounds have weak antiferromagnetic behaviors. Our success in preparing new crystalline Co-BTC based MOFs under different surfactant media could provide a new road to prepare new diverse MOFs through various combinations of surfactants. - Graphical abstract: Employing surfactants as reaction media, two new metal-organic frame-works (MOFs) have been successfully synthesized and magnetic study suggests that both compounds have weak antiferromagnetic behaviors. - Highlights: • Two novel metal-organic frame-works (MOFs). • Synthesis through surfactant-thermal condition. • weak antiferromagnetic behaviors for both compounds.

Surfactant-thermal method to prepare two new cobalt metal-organic frameworks

International Nuclear Information System (INIS)

Yu, Xianglin; Toh, Yong Siang; Zhao, Jun; Nie, Lina; Ye, Kaiqi; Wang, Yue; Li, Dongsheng; Zhang, Qichun

2015-01-01

Employing surfactants as reaction media, two new metal-organic frameworks (MOFs):(HTEA)_3[Co_3(BTC)_3] (NTU-Z33) and (HTEA)[Co_3(HBTC)_2(BTC)] (NTU-Z34) (H_3BTC=1,3,5-benzenetricarboxylic acid, TEA=trimethylamine, and NTU=Nanyang Technological University), have been successfully synthesized and fully characterized. Note that NTU-Z33 has an unusual trimeric [Co_3(COO)_9] secondary building unit (SBU). Magnetic characterization suggests that both compounds have weak antiferromagnetic behaviors. Our success in preparing new crystalline Co-BTC based MOFs under different surfactant media could provide a new road to prepare new diverse MOFs through various combinations of surfactants. - Graphical abstract: Employing surfactants as reaction media, two new metal-organic frame-works (MOFs) have been successfully synthesized and magnetic study suggests that both compounds have weak antiferromagnetic behaviors. - Highlights: • Two novel metal-organic frame-works (MOFs). • Synthesis through surfactant-thermal condition. • weak antiferromagnetic behaviors for both compounds.

Chelation in Metal Intoxication

Directory of Open Access Journals (Sweden)

Swaran J.S. Flora

2010-06-01

Full Text Available Chelation therapy is the preferred medical treatment for reducing the toxic effects of metals. Chelating agents are capable of binding to toxic metal ions to form complex structures which are easily excreted from the body removing them from intracellular or extracellular spaces. 2,3-Dimercaprol has long been the mainstay of chelation therapy for lead or arsenic poisoning, however its serious side effects have led researchers to develop less toxic analogues. Hydrophilic chelators like meso-2,3-dimercaptosuccinic acid effectively promote renal metal excretion, but their ability to access intracellular metals is weak. Newer strategies to address these drawbacks like combination therapy (use of structurally different chelating agents or co-administration of antioxidants have been reported recently. In this review we provide an update of the existing chelating agents and the various strategies available for the treatment of heavy metals and metalloid intoxications.

Improvement of Surface Layer Characteristics by Shot Lining

Science.gov (United States)

Harada, Yasunori

In the present study, lining of the metal with foils using shot peening was investigated to improve the surface layer characteristics. In the shot peening experiment, the foils set on the metal are pelted with hard particles traveling at a high velocity. The foils are bonded to the metal surface due to plastic deformation induced by the collision of the particles. The foils and the metal are heated to heighten the bondability because of the reduction of flow stress. Lining the metal with the hard powder sandwiched between two aluminum foil sheets was also attempted. In this experiment, a centrifugal shot peening machine wite an electrical heater was employed. The metals are commercially aluminium alloys and magnesium alloys, and the foils are commercially aluminum, titanium and nickel. The effects of shot speed and the heating temperature on the bondability were examined. Wear resistance was also evaluated by grinding. The foils were successfully bonded to the metal surface. It was found that the present method is effective in improving of surface layer characteristics.

An automated flow injection system for metal determination by flame atomic absorption spectrometry involving on-line fabric disk sorptive extraction technique.

Science.gov (United States)

Anthemidis, A; Kazantzi, V; Samanidou, V; Kabir, A; Furton, K G

2016-08-15

A novel flow injection-fabric disk sorptive extraction (FI-FDSE) system was developed for automated determination of trace metals. The platform was based on a minicolumn packed with sol-gel coated fabric media in the form of disks, incorporated into an on-line solid-phase extraction system, coupled with flame atomic absorption spectrometry (FAAS). This configuration provides minor backpressure, resulting in high loading flow rates and shorter analytical cycles. The potentials of this technique were demonstrated for trace lead and cadmium determination in environmental water samples. The applicability of different sol-gel coated FPSE media was investigated. The on-line formed complex of metal with ammonium pyrrolidine dithiocarbamate (APDC) was retained onto the fabric surface and methyl isobutyl ketone (MIBK) was used to elute the analytes prior to atomization. For 90s preconcentration time, enrichment factors of 140 and 38 and detection limits (3σ) of 1.8 and 0.4μgL(-1) were achieved for lead and cadmium determination, respectively, with a sampling frequency of 30h(-1). The accuracy of the proposed method was estimated by analyzing standard reference materials and spiked water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Experiments on sheet metal shearing

OpenAIRE

Gustafsson, Emil

2013-01-01

Within the sheet metal industry, different shear cutting technologies are commonly used in several processing steps, e.g. in cut to length lines, slitting lines, end cropping etc. Shearing has speed and cost advantages over competing cutting methods like laser and plasma cutting, but involves large forces on the equipment and large strains in the sheet material.Numerical models to predict forces and sheared edge geometry for different sheet metal grades and different shear parameter set-ups a...

Spectral, optical and cytotoxicity studies on 2-isonicotinoyl-N-phenylhydrazine-1-carboxamide(H3L) and some of its metal complexes

Science.gov (United States)

Hosny, Nasser M.; Hassan, Nader Y.; Mahmoud, Heba M.; Abdel-Rhman, Mohamed H.

2018-03-01

The ligand 2-isonicotinoyl-N-phenylhydrazine-1-carboxamide (H3L) and its metal complexes with Co(II), Ni(II), Cu(II) and Zn(II) acetates have been synthesized. The isolated compounds have been characterized by elemental analyses, FT-IR, 1H NMR, 13C NMR, ESR, mass, electronic spectra, electrical conductivity, effective magnetic moments and thermal analyses. The free organic ligand exists in the keto form, but in the metal complexes, it coordinates in the enol form. Four coordinated species were suggested for all the isolated metal complexes. The measured optical band gap values confirmed the presence of direct electronic transition and the semi-conductivity of the compounds. The ligand and its Zn(II) complex were examined as cytotoxic agent against HCT-116 and HePG-2. The ligand showed very strong cytotoxic effect against HePG-2, but moderate cytotoxicity against HCT-116. Zn(II) complex showed weak cytotoxicity against the two cell lines.

University Autonomy: Two Fault-Lines

Science.gov (United States)

Evans, G. R.

2010-01-01

The doctrine of university autonomy in the UK contains a least two major "fault-lines" where the structure is inherently weak and there is danger of functional breakdown. The first occurs at the junction between the institution and the state, the second within the institution, where the unity in policy-making between academic and…

Metal artifact reduction method using metal streaks image subtraction

International Nuclear Information System (INIS)

Pua, Rizza D.; Cho, Seung Ryong

2014-01-01

Many studies have been dedicated for metal artifact reduction (MAR); however, the methods are successful to varying degrees depending on situations. Sinogram in-painting, filtering, iterative method are some of the major categories of MAR. Each has its own merits and weaknesses. A combination of these methods or hybrid methods have also been developed to make use of the different benefits of two techniques and minimize the unfavorable results. Our method focuses on the in-paitning approach and a hybrid MAR described by Xia et al. Although in-painting scheme is an effective technique in reducing the primary metal artifacts, a major drawback is the reintroduction of new artifacts that can be caused by an inaccurate interpolation process. Furthermore, combining the segmented metal image to the corrected nonmetal image in the final step of a conventional inpainting approach causes an issue of incorrect metal pixel values. Our proposed method begins with a sinogram in-painting approach and ends with an image-based metal artifact reduction scheme. This work provides a simple, yet effective solution for reducing metal artifacts and acquiring the original metal pixel information. The proposed method demonstrated its effectiveness in a simulation setting. The proposed method showed image quality that is comparable to the standard MAR; however, quantitatively more accurate than the standard MAR

Weak matrix elements efforts on the lattice: Status and prospects

International Nuclear Information System (INIS)

Soni, A.

1995-01-01

Lattice approach to weak matrix elements is reviewed. Recent progress in treating heavy quarks on the lattice is briefly discussed. Illustrative sample of results obtained so far is given. Among them I elaborate on B K , line-integral B and B → K* γ . Experimental implications especially with regard to constraints on the Standard Model (i.e. Wolfenstein) parameters, V td measurements and expectations for B s -bar B s , oscillations are briefly discussed

Approximation of Moessbauer spectra of metallic glasses

International Nuclear Information System (INIS)

Miglierini, M.; Sitek, J.

1988-01-01

Moessbauer spectra of iron-rich metallic glasses are approximated by means of six broadened lines which have line position relations similar to those of α-Fe. It is shown via the results of the DISPA (dispersion mode vs. absorption mode) line shape analysis that each spectral peak is broadened owing to a sum of Lorentzian lines weighted by a Gaussian distribution in the peak position. Moessbauer parameters of amorphous metallic Fe 83 B 17 and Fe 40 Ni 40 B 20 alloys are presented, derived from the fitted spectra. (author). 2 figs., 2 tabs., 21 refs

Hartman effect and weak measurements that are not really weak

International Nuclear Information System (INIS)

Sokolovski, D.; Akhmatskaya, E.

2011-01-01

We show that in wave packet tunneling, localization of the transmitted particle amounts to a quantum measurement of the delay it experiences in the barrier. With no external degree of freedom involved, the envelope of the wave packet plays the role of the initial pointer state. Under tunneling conditions such ''self-measurement'' is necessarily weak, and the Hartman effect just reflects the general tendency of weak values to diverge, as postselection in the final state becomes improbable. We also demonstrate that it is a good precision, or a 'not really weak' quantum measurement: no matter how wide the barrier d, it is possible to transmit a wave packet with a width σ small compared to the observed advancement. As is the case with all weak measurements, the probability of transmission rapidly decreases with the ratio σ/d.

Extended Emission-Line Regions: Remnants of Quasar Superwinds?

Science.gov (United States)

Fu, Hai; Stockton, Alan

2009-01-01

We give an overview of our recent integral-field-unit spectroscopy of luminous extended emission-line regions (EELRs) around low-redshift quasars, including new observations of five fields. Previous work has shown that the most luminous EELRs are found almost exclusively around steep-spectrum radio-loud quasars, with apparently disordered global velocity fields, and little, if any, morphological correlation with either the host galaxy or the radio structure. Our new observations confirm and expand these results. The EELRs often show some clouds with velocities exceeding 500 km s-1, ranging up to 1100 km s-1, but the velocity dispersions, with few exceptions, are in the 30-100 km s-1 range. Emission-line ratios show that the EELRs are clearly photoionized by the quasars. Masses of the EELRs range up to 1010Msun. Essentially all of the EELRs show relatively low metallicities, and they are associated with quasars that, in contrast to most, show similarly low metallicities in their broad-line regions. The two objects in our sample that do not have classical double-lobed radio morphologies (3C 48, with a compact-steep-spectrum source; Mrk 1014, radio quiet, but with a weak compact-steep-spectrum source) are the only ones that appear to have recent star formation. While some of the less luminous EELRs may have other origins, the most likely explanation for those in our sample is that they are examples of gas swept out of the host galaxy by a large-solid-angle blast wave accompanying the production of the radio jets. The triggering of the quasar activity is almost certainly the result of the merger of a gas-rich galaxy with a massive, gas-poor galaxy hosting the supermassive black hole. Based in part on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the

Research on cutoff wavelength of dominant mode and field patterns in trapezoidal microshield lines

OpenAIRE

SUN, Hai; WU, Yujiang

2012-01-01

The influence of the position of the metallic signal strip on the cutoff characteristic of the dominant mode and the field patterns in 3 types of trapezoidal microshield lines are calculated by the edge-based finite element method. These trapezoidal microshield lines include trapezoidal microshield lines with a single signal line, dual signal lines, and 3 signal lines. The cutoff wavelength of the dominant mode can be adjusted by changing the dimensions of metallic signal strips as w...

Influence of Weak External Magnetic Field on Amorphous and Nanocrystalline Fe-based Alloys

Science.gov (United States)

Degmová, J.; Sitek, J.

2010-07-01

Nanoperm, Hitperm and Finamet amorphous and nanocrystalline alloys were measured by Mössbauer spectrometry in a weak external magnetic field of 0.5 T. It was shown that the most sensitive parameters of Mössbauer spectra are the intensities of the 2nd and the 5th lines. Rather small changes were observed also in the case of internal magnetic field values. The spectrum of nanocrystalline Nanoperm showed the increase in A23 parameter (ratio of line intensities) from 2.4 to 3.7 and decrease of internal magnetic field from 20 to 19 T for amorphous subspectrum under the influence of magnetic field. Spectrum of nanocrystalline Finemet shown decrease in A23 parameter from 3.5 to 2.6 almost without a change in the internal magnetic field value. In the case of amorphous Nanoperm and Finemet samples, the changes are almost negligible. Hitperm alloy showed the highest sensitivity to the weak magnetic field, when the A23 parameter increased from 0.4 to 2.5 in the external magnetic fields. The A23 parameter of crystalline subspectrum increased from 2.7 to 3.8 and the value of internal magnetic field corresponding to amorphous subspectrum increased from 22 to 24 T. The behavior of nanocrystalline alloys under weak external magnetic field was analyzed within the three-level relaxation model of magnetic dynamics in an assembly of single-domain particles.

ESR study of weakly irradiated organic conductors: TMTSF-DMTCNQ and (TMTSF)2PF6

International Nuclear Information System (INIS)

Forro, L.; Beuneu, F.

1982-01-01

ESR experiments are presented on irradiated TMTSF-DMTCNQ and (TMTSF) 2 PF 6 . They suggest that a weak disorder extends the metallic phases to low temperatures. Surprisingly, disorder has no effect on the ESR linewidth of (TMTSF) 2 PF 6 between 20 and 30 K, where the d.c. conductivity changes a lot with disorder. (author)

Stainless steel submerged arc weld fusion line toughness

International Nuclear Information System (INIS)

Rosenfield, A.R.; Held, P.R.; Wilkowski, G.M.

1995-04-01

This effort evaluated the fracture toughness of austenitic steel submerged-arc weld (SAW) fusion lines. The incentive was to explain why cracks grow into the fusion line in many pipe tests conducted with cracks initially centered in SAWS. The concern was that the fusion line may have a lower toughness than the SAW. It was found that the fusion line, Ji. was greater than the SAW toughness but much less than the base metal. Of greater importance may be that the crack growth resistance (JD-R) of the fusion line appeared to reach a steady-state value, while the SAW had a continually increasing JD-R curve. This explains why the cracks eventually turn to the fusion line in the pipe experiments. A method of incorporating these results would be to use the weld metal J-R curve up to the fusion-line steady-state J value. These results may be more important to LBB analyses than the ASME flaw evaluation procedures, since there is more crack growth with through-wall cracks in LBB analyses than for surface cracks in pipe flaw evaluations

Correlation between the sub-structure parameters and the manufacturing technologies of metal threads in historical textiles using X-ray line profile analysis

Energy Technology Data Exchange (ETDEWEB)

Csiszar, Gabor; Ungar, Tamas [Eoetvoes University Budapest, Department of Materials Physics, Budapest (Hungary); Jaro, Marta [Hungarian National Museum, Budapest (Hungary)

2013-06-15

Micro-structure can talk when documentation is missing. In ancient Roman or medieval periods, kings, queens, or just rich people decorated their clothes or even their horse covers richly with miniature jewels or metal threads. The origin or the fabrication techniques of these ancient threads is often unknown. Thirteen thread samples made of gold or gilt silver manufactured during the last sixteen hundred years are investigated for the micro-structure in terms of dislocation density, crystallite size, and planar defects. In a few cases, these features are compared with sub-structure of similar metallic threads prepared in modern, twentieth century workshops. The sub-structure is determined by X-ray line profile analysis, using high resolution diffractograms with negligible instrumental broadening. On the basis of the sub-structure parameters, we attempt to assess the metal-threads manufacturing procedures on samples stemming from the fourth century A.D. until now. (orig.)

Performance simulation of serpentine type metallic and non-metallic solar collector

International Nuclear Information System (INIS)

Al-Sageer, A. A. M.; Alowa, M. I.; Saad, M.

2006-01-01

This paper presents a theoretical investigation of metallic and non-metalic solar water collector models for evaluating its performane parameters. The determined parameters include heat removal factor , overall heat loss coefficients, heat gain, daily and hourly efficiencies. The present study reports that, under forced circulation lest, the non-metallic collector has an inferior performance parameters when compared to that of the metallic one. It was also revealed that the overall heat loss coefficients of both collectors show weak dependence on the flow rate variations. It was also noticed that the heat removal factor forboth models is more sensitive to the flow rate variations. Also noticed that the heat removal factor for both models is more sensitive to the flow rate variations. Also, a comparision of performance parameters of the theoretical and experimental studies showed good agreements for most hours of the day, except the results obtained at the early morning and late after noon hours.(Author)

Weak KAM theory for a weakly coupled system of Hamilton–Jacobi equations

KAUST Repository

Figalli, Alessio; Gomes, Diogo A.; Marcon, Diego

2016-01-01

Here, we extend the weak KAM and Aubry–Mather theories to optimal switching problems. We consider three issues: the analysis of the calculus of variations problem, the study of a generalized weak KAM theorem for solutions of weakly coupled systems of Hamilton–Jacobi equations, and the long-time behavior of time-dependent systems. We prove the existence and regularity of action minimizers, obtain necessary conditions for minimality, extend Fathi’s weak KAM theorem, and describe the asymptotic limit of the generalized Lax–Oleinik semigroup. © 2016, Springer-Verlag Berlin Heidelberg.

Weak KAM theory for a weakly coupled system of Hamilton–Jacobi equations

KAUST Repository

Figalli, Alessio

2016-06-23

Here, we extend the weak KAM and Aubry–Mather theories to optimal switching problems. We consider three issues: the analysis of the calculus of variations problem, the study of a generalized weak KAM theorem for solutions of weakly coupled systems of Hamilton–Jacobi equations, and the long-time behavior of time-dependent systems. We prove the existence and regularity of action minimizers, obtain necessary conditions for minimality, extend Fathi’s weak KAM theorem, and describe the asymptotic limit of the generalized Lax–Oleinik semigroup. © 2016, Springer-Verlag Berlin Heidelberg.

Dynamic analysis and vibration testing of CFRP drive-line system used in heavy-duty machine tool

Science.gov (United States)

Yang, Mo; Gui, Lin; Hu, Yefa; Ding, Guoping; Song, Chunsheng

2018-03-01

Low critical rotary speed and large vibration in the metal drive-line system of heavy-duty machine tool affect the machining precision seriously. Replacing metal drive-line with the CFRP drive-line can effectively solve this problem. Based on the composite laminated theory and the transfer matrix method (TMM), this paper puts forward a modified TMM to analyze dynamic characteristics of CFRP drive-line system. With this modified TMM, the CFRP drive-line of a heavy vertical miller is analyzed. And the finite element modal analysis model of the shafting is established. The results of the modified TMM and finite element analysis (FEA) show that the modified TMM can effectively predict the critical rotary speed of CFRP drive-line. And the critical rotary speed of CFRP drive-line is 20% higher than that of the original metal drive-line. Then, the vibration of the CFRP and the metal drive-line were tested. The test results show that application of the CFRP drive shaft in the drive-line can effectively reduce the vibration of the heavy-duty machine tool.

A multi-channel bioluminescent bacterial biosensor for the on-line detection of metals and toxicity. Part II: technical development and proof of concept of the biosensor

Energy Technology Data Exchange (ETDEWEB)

Charrier, Thomas; Thouand, Gerald [UMR CNRS 6144 GEPEA, CBAC, Nantes University, PRES UNAM, Campus de la Courtaisiere-IUT, La Roche-sur-Yon cedex (France); Chapeau, Cyrille [Biolumine, Biokar Diagnostic, Rue des Quarante Mines ZAC de Ther-Allonne, Beauvais Cedex (France); Bendria, Loubna; Daniel, Philippe [UMR CNRS 6087 LPEC, Universite du Maine, Av Olivier Messiaen, Le Mans cedex 9 (France); Picart, Pascal [UMR CNRS 6613 IAM-LAUM, Ecole Nationale des Ingenieurs du Mans, Universite du Maine, Le Mans Cedex 9 (France)

2011-05-15

This research study deals with the on-line detection of heavy metals and toxicity within the context of environmental pollution monitoring. It describes the construction and the proof of concept of a multi-channel bioluminescent bacterial biosensor in immobilized phase: Lumisens3. This new versatile device, designed for the non-stop analysis of water pollution, enables the insertion of any bioluminescent strains (inducible or constitutive), immobilized in a multi-well removable card. The technical design of Lumisens3 has benefited from both a classical and a robust approach and includes four main parts: (1) a dedicated removable card contains 64 wells, 3 mm in depth, arranged in eight grooves within which bacteria are immobilized, (2) this card is incubated on a Pelletier block with a CCD cooled camera on top for bioluminescence monitoring, (3) a fluidic network feeds the card with the sample to be analyzed and finally (4) a dedicated computer interface, BIOLUX 1.0, controls all the elements of the biosensor, allowing it to operate autonomously. The proof of concept of this biosensor was performed using a set of four bioluminescent bacteria (Escherichia coli DH1 pBzntlux, pBarslux, pBcoplux, and E. coli XL1 pBfiluxCDABE) in the on-line detection of CdCl{sub 2} 0.5 {mu}M and As{sub 2}O{sub 3} 5 {mu}M from an influent. When considering metals individually, the ''fingerprints'' from the biosensor were as expected. However, when metals were mixed together, cross reaction and synergistic effects were detected. This biosensor allowed us to demonstrate the simultaneous on-line cross detection of one or several heavy metals as well as the measurement of the overall toxicity of the sample. (orig.)

Heavy metal incorporated helium ion active hybrid non-chemically amplified resists: Nano-patterning with low line edge roughness

Directory of Open Access Journals (Sweden)

Pulikanti Guruprasad Reddy

2017-08-01

Full Text Available Helium (He ion lithography is being considered as one of the most promising and emerging technology for the manufacturing of next generation integrated circuits (ICs at nanolevel. However, He-ion active resists are rarely reported. In this context, we are introducing a new non-chemically amplified hybrid resist (n-CAR, MAPDSA-MAPDST, for high resolution He-ion beam lithography (HBL applications. In the resist architecture, 2.15 % antimony is incorporated as heavy metal in the form of antimonate. This newly developed resists has successfully used for patterning 20 nm negative tone features at a dose of 60 μC/cm2. The resist offered very low line edge roughness (1.27±0.31 nm for 20 nm line features. To our knowledge, this is the first He-ion active hybrid resist for nanopatterning. The contrast (γ and sensitivity (E0 of this resist were calculated from the contrast curve as 0.73 and 7.2 μC/cm2, respectively.

Heavy metal incorporated helium ion active hybrid non-chemically amplified resists: Nano-patterning with low line edge roughness

Science.gov (United States)

Reddy, Pulikanti Guruprasad; Thakur, Neha; Lee, Chien-Lin; Chien, Sheng-Wei; Pradeep, Chullikkattil P.; Ghosh, Subrata; Tsai, Kuen-Yu; Gonsalves, Kenneth E.

2017-08-01

Helium (He) ion lithography is being considered as one of the most promising and emerging technology for the manufacturing of next generation integrated circuits (ICs) at nanolevel. However, He-ion active resists are rarely reported. In this context, we are introducing a new non-chemically amplified hybrid resist (n-CAR), MAPDSA-MAPDST, for high resolution He-ion beam lithography (HBL) applications. In the resist architecture, 2.15 % antimony is incorporated as heavy metal in the form of antimonate. This newly developed resists has successfully used for patterning 20 nm negative tone features at a dose of 60 μC/cm2. The resist offered very low line edge roughness (1.27±0.31 nm) for 20 nm line features. To our knowledge, this is the first He-ion active hybrid resist for nanopatterning. The contrast (γ) and sensitivity (E0) of this resist were calculated from the contrast curve as 0.73 and 7.2 μC/cm2, respectively.

The Biological Effects of Weak Electromagnetic Fields

International Nuclear Information System (INIS)

Algattawi, A.; Elshyrih, H.

2010-01-01

Many studies investigated that weak electromagnetic fields remove calcium ions bound to the membranes of living cells, making them more likely to tear,. There is an enzyme that destroys DNA this enzyme leaking through the membranes of lysosomes explains the fragmentation of DNA. This case was seen in cells exposed to mobile phone signals. When this occurs in the germ line it reduces fertility and predicts genetic damage in future generations. Although leakage of calcium ions into the cytosol (the main part of the cell) accelerates the growth, but it also promotes the growth of tumors. Leakage of calcium ions into neurons (brain cells) makes nerve impulses accounting for pain and other neurological symptoms in electro sensitive. It also reduces the signal to noise ratio of the brain making it less likely to respond. This may be partially responsible for the increased accident rate of drivers using mobile phones. More details for the molecular mechanisms to explain characteristics of electromagnetic exposure are needed, e.g. I) why weak fields are more effective than strong ones, II) why some frequencies such as 16 Hz are especially potent and III) why pulsed fields do more damage

Correlated effective field theory in transition metal compounds

International Nuclear Information System (INIS)

Mukhopadhyay, Subhasis; Chatterjee, Ibha

2004-01-01

Mean field theory is good enough to study the physical properties at higher temperatures and in higher dimensions. It explains the critical phenomena in a restricted sense. Near the critical temperatures, when fluctuations become important, it may not give the correct results. Similarly in low dimensions, the correlations become important and the mean field theory seems to be inadequate to explain the physical phenomena. At low-temperatures too, the quantum correlations become important and these effects are to be treated in an appropriate way. In 1974, Prof. M.E. Lines of Bell Laboratories, developed a theory which goes beyond the mean field theory and is known as the correlated effective field (CEF) theory. It takes into account the fluctuations in a semiempirical way. Lines and his collaborators used this theory to explain the short-range correlations and their anisotropy in the paramagnetic phase. Later Suzuki et al., Chatterjee and Desai, Mukhopadhyay and Chatterjee applied this theory to the magnetically ordered phase and a tremendous success of the theory has been found in real systems. The success of the CEF theory is discussed in this review. In order to highlight the success of this theory, earlier effective field theories and their improvements over mean field theories e.g., Bethe-Peierls-Weiss method, reaction field approximation, etc., are also discussed in this review for completeness. The beauty of the CEF theory is that it is mean field-like, but captures the essential physics of real systems to a great extent. However, this is a weak correlated theory and as a result is inappropriate for the metallic phase when strong correlations become important. In recent times, transition metal oxides become important due to the discovery of the high-temperature superconductivity and the colossal magnetoresistance phenomena. These oxides seem to be Mott insulators and undergo an insulator to metal transition by applying magnetic field, pressure and by changing

Dark-Matter Particles without Weak-Scale Masses or Weak Interactions

International Nuclear Information System (INIS)

Feng, Jonathan L.; Kumar, Jason

2008-01-01

We propose that dark matter is composed of particles that naturally have the correct thermal relic density, but have neither weak-scale masses nor weak interactions. These models emerge naturally from gauge-mediated supersymmetry breaking, where they elegantly solve the dark-matter problem. The framework accommodates single or multiple component dark matter, dark-matter masses from 10 MeV to 10 TeV, and interaction strengths from gravitational to strong. These candidates enhance many direct and indirect signals relative to weakly interacting massive particles and have qualitatively new implications for dark-matter searches and cosmological implications for colliders

Line profile analyses of rhodium metal obtained by decomposition of rhodium carbonyl

International Nuclear Information System (INIS)

Chandra, D.; Mandalia, H.; Garner, M.L.; Blakely, M.K.; Lau, K.H.

1995-01-01

Metal carbonyls are important for chemical vapor deposition (CVD) of metals and alloys and formation of high surface area metallic particles which have potential applications as catalysts. Rhodium carbonyl [Rh 6 (CO) 16 ] produces high surface area metallic particles whose structure has been reported as monoclinic (I2/a) with lattice dimensions, a=17.00(±0.03)Angstrom, b=9.78(±0.02)Angstrom, c=17.53(±0.03)Angstrom and Β=121 degrees 45' ± 30' at room temperature. Generally, metal carbonyl crystals dissociate under vacuum as carbonyl gas and decompose to metallic crystals and carbon monoxide at higher temperatures. However, the behavior of rhodium carbonyl crystals is different; they decompose directly to metallic rhodium without the formation of rhodium carbonyl gas in vacuum. Several residual fine grains of rhodium metal are found after the decomposition in vacuum at relatively low temperatures. The metallic samples of rhodium were obtained from vapor pressure experiments using torsion Knudsen-effusion apparatus. X-ray diffraction analyses performed on these gains showed severely broadened Bragg reflections indicative of small particle size and/or lattice microgram. In this study, a comparison of lattice strains and domain sizes obtained by integral breadth and Fourier methods has been made. In addition a comparison of the lattice strains and domain sizes has been made between the Cauchy, Gaussian, Cauchy-Gaussian and Aqua integral breadth methods

Subaru Weak-Lensing Survey II: Multi-Object Spectroscopy and Cluster Masses

Science.gov (United States)

Hamana, Takashi; Miyazaki, Satoshi; Kashikawa, Nobunari; Ellis, Richard S.; Massey, Richard J.; Refregier, Alexandre; Taylor, James E.

2009-08-01

We present the first results of a multi-object spectroscopic campaign to follow up cluster candidates located via weak lensing. Our main goals are to search for spatial concentrations of galaxies that are plausible optical counterparts of the weak-lensing signals, and to determine the cluster redshifts from those of member galaxies. Around each of 36 targeted cluster candidates, we obtained 15-32 galaxy redshifts. For 28 of these targets, we confirmed a secure cluster identification, with more than five spectroscopic galaxies within a velocity of ±3000km s-1. This includes three cases where two clusters at different redshifts are projected along the same line-of-sight. In 6 of the 8 unconfirmed targets, we found multiple small galaxy concentrations at different redshifts, each containing at least three spectroscopic galaxies. The weak-lensing signal around those systems was thus probably created by the projection of groups or small clusters along the same line-of-sight. In both of the remaining two targets, a single small galaxy concentration was found. In some candidate super-cluster systems, we found additional evidence of filaments connecting the main density peak to an additional nearby structure. For a subsample of our most cleanly measured clusters, we investigated the statistical relation between their weak-lensing mass (MNFW, σSIS) and the velocity dispersion of their member galaxies (σv), comparing our sample with optically and X-ray selected samples from the literature. Our lensing-selected clusters are consistent with σv = σSIS, with a similar scatter to that of optically and X-ray selected clusters. We also derived an empirical relation between the cluster mass and the galaxy velocity dispersion, M200E(z) = 11.0 × 1014 × (σv/1000km s-1)3.0 h-1 Modot, which is in reasonable agreement with predictions of N-body simulations in the Λ CDM cosmology.

Dynamic analysis and vibration testing of CFRP drive-line system used in heavy-duty machine tool

Directory of Open Access Journals (Sweden)

Mo Yang

2018-03-01

Full Text Available Low critical rotary speed and large vibration in the metal drive-line system of heavy-duty machine tool affect the machining precision seriously. Replacing metal drive-line with the CFRP drive-line can effectively solve this problem. Based on the composite laminated theory and the transfer matrix method (TMM, this paper puts forward a modified TMM to analyze dynamic characteristics of CFRP drive-line system. With this modified TMM, the CFRP drive-line of a heavy vertical miller is analyzed. And the finite element modal analysis model of the shafting is established. The results of the modified TMM and finite element analysis (FEA show that the modified TMM can effectively predict the critical rotary speed of CFRP drive-line. And the critical rotary speed of CFRP drive-line is 20% higher than that of the original metal drive-line. Then, the vibration of the CFRP and the metal drive-line were tested. The test results show that application of the CFRP drive shaft in the drive-line can effectively reduce the vibration of the heavy-duty machine tool. Keywords: CFRP drive-line system, Dynamic behavior, Transfer matrix, Vibration measurement

Automatic on-line detection system design research on internal defects of metal materials based on optical fiber F-P sensing technology

Science.gov (United States)

Xia, Liu; Shan, Ning; Chao, Ban; Caoshan, Wang

2016-10-01

Metal materials have been used in aerospace and other industrial fields widely because of its excellent characteristics, so its internal defects detection is very important. Ultrasound technology is used widely in the fields of nondestructive detection because of its excellent characteristic. But the conventional detection instrument for ultrasound, which has shortcomings such as low intelligent level and long development cycles, limits its development. In this paper, the theory of ultrasound detection is analyzed. A computational method of the defects distributional position is given. The non-contact type optical fiber F-P interference cavity structure is designed and the length of origin cavity is given. The real-time on-line ultrasound detecting experiment devices for internal defects of metal materials is established based on the optical fiber F-P sensing system. The virtual instrument of automation ultrasound detection internal defects is developed based on LabVIEW software and the experimental study is carried out. The results show that this system can be used in internal defect real-time on-line locating of engineering structures effectively. This system has higher measurement precision. Relative error is 6.7%. It can be met the requirement of engineering practice. The system is characterized by simple operation, easy realization. The software has a friendly interface, good expansibility, and high intelligent level.

Determination of Heavy Metal Concentrations in Normal and Pathological Human Endometrial Biopsies and In Vitro Regulation of Gene Expression by Metals in the Ishikawa and Hec-1b Endometrial Cell Line.

Directory of Open Access Journals (Sweden)

Erwan Guyot

Full Text Available It is well known that several metals, such as lead, mercury, cadmium, and vanadium, can mimic the effects of estrogens (metallo-estrogens. Nevertheless, there are only a few studies that have assessed the effects of toxic metals on the female genital tract and, in particular, endometrial tissue. In this context, we measured the concentrations of several trace elements in human endometrial tissue samples from individuals with hyperplasia or adenocarcinoma and in normal tissues. Hyperplasic endometrial tissue has a 4-fold higher concentration of mercury than normal tissue. Mercury can affect both the AhR and ROS signaling pathways. Thus, we investigated the possible toxic effects of mercury by in vitro studies. We found that mercury increases oxidative stress (increased HO1 and NQO1 mRNA levels and alters the cytoskeleton in the human endometrial Ishikawa cell line and to a lesser extent, in the "less-differentiated" human endometrial Hec-1b cells. The results might help to explain a potential link between this metal and the occurrence of endometrial hyperplasia.

Determination of Heavy Metal Concentrations in Normal and Pathological Human Endometrial Biopsies and In Vitro Regulation of Gene Expression by Metals in the Ishikawa and Hec-1b Endometrial Cell Line

Science.gov (United States)

Tomkiewicz, Céline; Leblanc, Alix; Pierre, Stéphane; El Balkhi, Souleiman; Le Frère-Belda, Marie-Aude; Lecuru, Fabrice; Poupon, Joël; Barouki, Robert; Aggerbeck, Martine; Coumoul, Xavier

2015-01-01

It is well known that several metals, such as lead, mercury, cadmium, and vanadium, can mimic the effects of estrogens (metallo-estrogens). Nevertheless, there are only a few studies that have assessed the effects of toxic metals on the female genital tract and, in particular, endometrial tissue. In this context, we measured the concentrations of several trace elements in human endometrial tissue samples from individuals with hyperplasia or adenocarcinoma and in normal tissues. Hyperplasic endometrial tissue has a 4-fold higher concentration of mercury than normal tissue. Mercury can affect both the AhR and ROS signaling pathways. Thus, we investigated the possible toxic effects of mercury by in vitro studies. We found that mercury increases oxidative stress (increased HO1 and NQO1 mRNA levels) and alters the cytoskeleton in the human endometrial Ishikawa cell line and to a lesser extent, in the “less-differentiated” human endometrial Hec-1b cells. The results might help to explain a potential link between this metal and the occurrence of endometrial hyperplasia. PMID:26600472

Impurity Trapping of Positive Muons in Metals

CERN Multimedia

2002-01-01

Polarized positive muons are implanted into metal samples. In an applied magnetic field the muon spin precession is studied. The line width in the precession frequency spectrum gives information about the static and dynamic properties of muons in a metal lattice. At temperatures where the muon is immobile within its lifetime the line width gives information about the site of location. At temperatures where the muon is mobile, the line width gives information on the diffusion process. It is known from experiments on quasi-elastic neutron scattering on hydrogen in niobium that interstitial impurities like nitrogen tend to act as traps for hydrogen. These trapping effects have now been studied systematically for muons in both f.c.c. metals (aluminium and copper) and b.c.c. metals (mainly niobium). Direct information on the trapping rates and the nature of the diffusion processes can be obtained since the muonic lifetime covers a time range where many of these processes occur.\\\\ \\\\ Mathematical models are set up ...

A directly heated electron beam line source

International Nuclear Information System (INIS)

Iqbal, M.; Masood, K.; Rafiq, M.; Chaudhry, M.A.

2002-05-01

A 140-mm cathode length, Electron Beam Line Source with a high degree of focusing of the beam is constructed. The design principles and basic characteristic considerations for electron beam line source consists of parallel plate electrode geometric array as well as a beam power of 35kW are worked out. The dimensions of the beam at the work site are 1.25xl00mm. The gun is designed basically for the study of evaporation and deposition characteristic of refractory metals for laboratory use. However, it may be equally used for melting and casting of these metals. (author)

Dimensional crossover of electron weak localization in ZnO/TiO{sub x} stacked layers grown by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Saha, D., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Misra, P., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Joshi, M. P.; Kukreja, L. M. [Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Bhartiya, S. [Laser Materials Development & Devices Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Gupta, M. [UGC-DAE Consortium for Scientific Research, Indore 452 017 (India)

2016-01-25

We report on the dimensional crossover of electron weak localization in ZnO/TiO{sub x} stacked layers having well-defined and spatially-localized Ti dopant profiles along film thickness. These films were grown by in situ incorporation of sub-monolayer TiO{sub x} on the growing ZnO film surface and subsequent overgrowth of thin conducting ZnO spacer layer using atomic layer deposition. Film thickness was varied in the range of ∼6–65 nm by vertically stacking different numbers (n = 1–7) of ZnO/TiO{sub x} layers of nearly identical dopant-profiles. The evolution of zero-field sheet resistance (R{sub ◻}) versus temperature with decreasing film thickness showed a metal to insulator transition. On the metallic side of the metal-insulator transition, R{sub ◻}(T) and magnetoresistance data were found to be well corroborated with the theoretical framework of electron weak localization in the diffusive transport regime. The temperature dependence of both R{sub ◻} and inelastic scattering length provided strong evidence for a smooth crossover from 2D to 3D weak localization behaviour. Results of this study provide deeper insight into the electron transport in low-dimensional n-type ZnO/TiO{sub x} stacked layers which have potential applications in the field of transparent oxide electronics.

High-resolution Laboratory Measurements of Coronal Lines near the Fe IX Line at 171 Å

Science.gov (United States)

Beiersdorfer, Peter; Träbert, Elmar

2018-02-01

We present high-resolution laboratory measurements in the spectral region between 165 and 175 Å that focus on the emission from various ions of C, O, F, Ne, S, Ar, Fe, and Ni. This wavelength region is centered on the λ171 Fe IX channel of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory, and we place special emphasis on the weaker emission lines of Fe IX predicted in this region. In general, our measurements show a multitude of weak lines missing in the current databases, where the emission lines of Ni are probably most in need of further identification and reclassification. We also find that the wavelengths of some of the known lines need updating. Using the multi-reference Møller–Plesset method for wavelength predictions and collisional-radiative modeling of the line intensities, we have made tentative assignments of more than a dozen lines to the spectrum of Fe IX, some of which have formerly been identified as Fe VII, Fe XIV, or Fe XVI lines. Several Fe features remain unassigned, although they appear to be either Fe VII or Fe X lines. Further work will be needed to complete and correct the spectral line lists in this wavelength region.

Improvement on post-OPC verification efficiency for contact/via coverage check by final CD biasing of metal lines and considering their location on the metal layout

Science.gov (United States)

Kim, Youngmi; Choi, Jae-Young; Choi, Kwangseon; Choi, Jung-Hoe; Lee, Sooryong

2011-04-01

As IC design complexity keeps increasing, it is more and more difficult to ensure the pattern transfer after optical proximity correction (OPC) due to the continuous reduction of layout dimensions and lithographic limitation by k1 factor. To guarantee the imaging fidelity, resolution enhancement technologies (RET) such as off-axis illumination (OAI), different types of phase shift masks and OPC technique have been developed. In case of model-based OPC, to cross-confirm the contour image versus target layout, post-OPC verification solutions continuously keep developed - contour generation method and matching it to target structure, method for filtering and sorting the patterns to eliminate false errors and duplicate patterns. The way to detect only real errors by excluding false errors is the most important thing for accurate and fast verification process - to save not only reviewing time and engineer resource, but also whole wafer process time and so on. In general case of post-OPC verification for metal-contact/via coverage (CC) check, verification solution outputs huge of errors due to borderless design, so it is too difficult to review and correct all points of them. It should make OPC engineer to miss the real defect, and may it cause the delay time to market, at least. In this paper, we studied method for increasing efficiency of post-OPC verification, especially for the case of CC check. For metal layers, final CD after etch process shows various CD bias, which depends on distance with neighbor patterns, so it is more reasonable that consider final metal shape to confirm the contact/via coverage. Through the optimization of biasing rule for different pitches and shapes of metal lines, we could get more accurate and efficient verification results and decrease the time for review to find real errors. In this paper, the suggestion in order to increase efficiency of OPC verification process by using simple biasing rule to metal layout instead of etch model

The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere IV. On the Nature of the Chromosphere

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2013-07-01

Full Text Available The chromosphere is the site of weak emission lines characterizing the flash spectrum observed for a few seconds during a total eclipse. This layer of the solar atmosphere is known to possess an opaque Hα emission and a great number of spicules, which can extend well above the photosphere. A stunning variety of hydrogen emission lines have been observed in this region. The production of these lines has provided the seventeenth line of evidence that the Sun is comprised of condensed matter (Robitaille P.M. Liquid Metallic Hydrogen II: A critical assessment of current and primordial helium levels in Sun. Progr. Phys., 2013, v. 2, 35–47. Contrary to the gaseous solar models, the simplest mechanism for the production of emission lines is the evaporation of excited atoms from condensed surfaces existing within the chromosphere, as found in spicules. This is reminiscent of the chemiluminescence which occurs during the condensation of silver clusters (Konig L., Rabin I., Schultze W., and Ertl G. Chemiluminescence in the Agglomeration of Metal Clusters. Science, v. 274, no. 5291, 1353–1355. The process associated with spicule formation is an exothermic one, requiring the transport of energy away from the site of condensation. As atoms leave localized surfaces, their electrons can occupy any energy level and, hence, a wide variety of emission lines are produced. In this regard, it is hypothesized that the presence of hydrides on the Sun can also facilitate hydrogen condensation in the chromosphere. The associated line emission from main group and transition elements constitutes the thirtieth line of evidence that the Sun is condensed matter. Condensation processes also help to explain why spicules manifest an apparently constant temperature over their entire length. Since the corona supports magnetic field lines, the random orientations associated with spicule formation suggests that the hydrogen condensates in the chromosphere are not metallic in

Weyl Semimetal to Metal Phase Transitions Driven by Quasiperiodic Potentials

Science.gov (United States)

Pixley, J. H.; Wilson, Justin H.; Huse, David A.; Gopalakrishnan, Sarang

2018-05-01

We explore the stability of three-dimensional Weyl and Dirac semimetals subject to quasiperiodic potentials. We present numerical evidence that the semimetal is stable for weak quasiperiodic potentials, despite being unstable for weak random potentials. As the quasiperiodic potential strength increases, the semimetal transitions to a metal, then to an "inverted" semimetal, and then finally to a metal again. The semimetal and metal are distinguished by the density of states at the Weyl point, as well as by level statistics, transport, and the momentum-space structure of eigenstates near the Weyl point. The critical properties of the transitions in quasiperiodic systems differ from those in random systems: we do not find a clear critical scaling regime in energy; instead, at the quasiperiodic transitions, the density of states appears to jump abruptly (and discontinuously to within our resolution).

Transfer and accumulation of metals in a soil-diet-wood mouse food chain along a metal pollution gradient

International Nuclear Information System (INIS)

Rogival, Damien; Scheirs, Jan; Blust, Ronny

2007-01-01

We studied the accumulation and transfer of As, Cd, Cu, Pb and Zn in the compartments of a soil-diet-wood mouse (Apodemus sylvaticus) food chain at five sites located along a metal pollution gradient. We observed a clear gradient in metal exposure at increasing distance from the smelter in all compartments of the food chain for the non-essential metals. The gradient was less clear or absent for the essential metals in acorn and mice target tissues. Regression analysis showed overall strong relationships within the soil-diet and diet-wood mouse compartments for the non-essential metals, while relationships for the essential metals were weak or absent. Total metal in soil appeared as a better predictor for the diet metal content than the available metal fraction. Our results suggest a more important transfer of non-essential elements through the food chain than essential elements, which is probably a consequence of homeostatic control of the latter group. - Non-essential metal transfer through a soil-diet-wood mouse food chain is more important than essential metal transfer

Weak mixing below the weak scale in dark-matter direct detection

Science.gov (United States)

Brod, Joachim; Grinstein, Benjamin; Stamou, Emmanuel; Zupan, Jure

2018-02-01

If dark matter couples predominantly to the axial-vector currents with heavy quarks, the leading contribution to dark-matter scattering on nuclei is either due to one-loop weak corrections or due to the heavy-quark axial charges of the nucleons. We calculate the effects of Higgs and weak gauge-boson exchanges for dark matter coupling to heavy-quark axial-vector currents in an effective theory below the weak scale. By explicit computation, we show that the leading-logarithmic QCD corrections are important, and thus resum them to all orders using the renormalization group.

Photometric metal abundances for twenty clusters

International Nuclear Information System (INIS)

Jennens, P.A.; Helfer, H.L.

1975-01-01

Metal abundances, colour excesses and distance moduli have been determined for individual giant stars, using UBViyz photometry, in NGC 188, 559, 752, 1245, 1342, 1907, 1912, 2099, 5139 (ω cen), 5316, 5617, 5822, 5823, 6067, IC 4651, 6819, 6940, 7142, 7261 and 7789. All six clusters with ages 3 to 8x10 9 yr have metal abundances agreeing with one another; their average value of [Fe/H]=-0.24+-0.05, agrees with the average found for the bright K-giants near the Sun. All six clusters are at least 140pc from the galactic plane. For the younger clusters less than approximately 10 9 yr old, one-third are metal deficient. The very young cluster, NGC 559, is probably very metal weak. (author)

Bagging Weak Predictors

DEFF Research Database (Denmark)

Lukas, Manuel; Hillebrand, Eric

Relations between economic variables can often not be exploited for forecasting, suggesting that predictors are weak in the sense that estimation uncertainty is larger than bias from ignoring the relation. In this paper, we propose a novel bagging predictor designed for such weak predictor variab...

Asymmetries of the solar Ca II lines

International Nuclear Information System (INIS)

Heasley, J.N.

1975-01-01

A theoretical study of the influence of propagating acoustic pulses in the solar chromosphere upon the line profiles of the Ca II resonance and infrared triplet lines has been made. The major objective has been to explain the observed asymmetries seen in the cores of the H and K lines and to predict the temporal behavior of the infrared lines caused by passing acoustic or shock pulses. The velocities in the pulses, calculated from weak shock theory, have been included consistently in the non-LTE calculations. The results of the calculations show that these lines are very sensitive to perturbations in the background atmosphere caused by the pulses. Only minor changes in the line shapes result from including the velocities consistently in the line source function calculations. The qualitative changes in the line profiles vary markedly with the strength of the shock pulses. The observed differences in the K line profiles seen on the quiet Sun can be explained in terms of a spectrum of pulses with different wavelengths and initial amplitudes in the photosphere. (Auth.)

Heavy metals and soil microbes

NARCIS (Netherlands)

Giller, K.E.; Witter, E.; McGrath, S.

2009-01-01

The discovery in the early 1980s that soil microorganisms, and in particular the symbiotic bacteria Rhizobium, were highly sensitive to heavy metals initiated a new line of research. This has given us important insights into a range of topics: ecotoxicology, bioavailability of heavy metals, the role

Slovenian System for Protecting Against Radioactive Material in Scrap Metal Shipments

Energy Technology Data Exchange (ETDEWEB)

Stritar, A.; Cesarek, J.; Vokal Nemec, B., E-mail: andrej.stritar@gov.si [Slovenian Nuclear Safety Administration, Ljubljana (Slovenia)

2011-07-15

The Slovenian experience shows that the majority of detected orphan sources are associated with imports of scrap metal to Slovenia and transits of that material through Slovenia. Such orphan sources originate from past industrial activities and weak regulatory control in the countries of origin. In order to minimise the number of sources outside regulatory control several regulatory and law enforcement measures have been implemented. To prevent illicit trafficking across the border the 'First line of defence' - customs and police - are equipped with radiation detection devices. Since 2002, the Slovenian Nuclear Safety Administration (SNSA) has provided a 24-hour on-duty officer, who gives advice in case of the discovery of an orphan source. The majority of scrap metal collectors and re-cyclers are equipped with portal monitors and/or hand-held radiation detection equipment. Generally, good cooperation has been established between different organizations within Slovenia, with neighbouring countries and with some international organizations. To regulate the scrap metal activities, a new Decree on checking the radioactivity of shipments of metal scrap has been in force since 1 January 2008. This decree requires that every importer has to present a certificate of radiation measurement before any shipment of scrap metal is brought into Slovenia. Such measurements can be performed only by certified organizations. These organizations can obtain certification from the SNSA providing that they have the prescribed measuring devices, adequate training and procedures, and that their capabilities have been checked by a technical support organization. The experience after one year of application of the decree is positive. Awareness, including the adequacy of response, has increased. The paper discusses the general scheme for protection against illicit radioactive material in scrap metal shipments and the Slovenian experience in the last decade. (author)

THE METALLICITIES OF LOW STELLAR MASS GALAXIES AND THE SCATTER IN THE MASS-METALLICITY RELATION

International Nuclear Information System (INIS)

Zahid, H. J.; Bresolin, F.; Kewley, L. J.; Coil, A. L.; Davé, R.

2012-01-01

In this investigation, we quantify the metallicities of low-mass galaxies by constructing the most comprehensive census to date. We use galaxies from the Sloan Digital Sky Survey (SDSS) and DEEP2 survey and estimate metallicities from their optical emission lines. We also use two smaller samples from the literature that have metallicities determined by the direct method using the temperature sensitive [O III]λ4363 line. We examine the scatter in the local mass-metallicity (MZ) relation determined from ∼20,000 star-forming galaxies in the SDSS and show that it is larger at lower stellar masses, consistent with the theoretical scatter in the MZ relation determined from hydrodynamical simulations. We determine a lower limit for the scatter in metallicities of galaxies down to stellar masses of ∼10 7 M ☉ which is only slightly smaller than the expected scatter inferred from the SDSS MZ relation and significantly larger than what has been previously established in the literature. The average metallicity of star-forming galaxies increases with stellar mass. By examining the scatter in the SDSS MZ relation, we show that this is mostly due to the lowest metallicity galaxies. The population of low-mass, metal-rich galaxies have properties that are consistent with previously identified galaxies that may be transitional objects between gas-rich dwarf irregulars and gas-poor dwarf spheroidals and ellipticals.

Post-quantum attacks on key distribution schemes in the presence of weakly stochastic sources

International Nuclear Information System (INIS)

Al–Safi, S W; Wilmott, C M

2015-01-01

It has been established that the security of quantum key distribution protocols can be severely compromised were one to permit an eavesdropper to possess a very limited knowledge of the random sources used between the communicating parties. While such knowledge should always be expected in realistic experimental conditions, the result itself opened a new line of research to fully account for real-world weak randomness threats to quantum cryptography. Here we expand of this novel idea by describing a key distribution scheme that is provably secure against general attacks by a post-quantum adversary. We then discuss possible security consequences for such schemes under the assumption of weak randomness. (paper)

Compatibility between weak gel and microorganisms in weak gel-assisted microbial enhanced oil recovery.

Science.gov (United States)

Qi, Yi-Bin; Zheng, Cheng-Gang; Lv, Cheng-Yuan; Lun, Zeng-Min; Ma, Tao

2018-03-20

To investigate weak gel-assisted microbial flooding in Block Wang Long Zhuang in the Jiangsu Oilfield, the compatibility of weak gel and microbe was evaluated using laboratory experiments. Bacillus sp. W5 was isolated from the formation water in Block Wang Long Zhuang. The rate of oil degradation reached 178 mg/day, and the rate of viscosity reduction reached 75.3%. Strain W5 could produce lipopeptide with a yield of 1254 mg/L. Emulsified crude oil was dispersed in the microbial degradation system, and the average diameter of the emulsified oil particles was 18.54 μm. Bacillus sp. W5 did not affect the rheological properties of the weak gel, and the presence of the weak gel did not significantly affect bacterial reproduction (as indicated by an unchanged microbial biomass), emulsification (surface tension is 35.56 mN/m and average oil particles size is 21.38 μm), oil degradation (162 mg/day) and oil viscosity reduction (72.7%). Core-flooding experiments indicated oil recovery of 23.6% when both weak gel and Bacillus sp. W5 were injected into the system, 14.76% when only the weak gel was injected, and 9.78% with strain W5 was injected without the weak gel. The results demonstrate good compatibility between strains W5 and the weak gel and highlight the application potential of weak gel-assisted microbial flooding. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Fabrication of Metallic Hollow Nanoparticles

Science.gov (United States)

Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

2016-01-01

Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

The Intrinsically X-Ray-weak Quasar PHL 1811. II. Optical and UV Spectra and Analysis

Science.gov (United States)

Leighly, Karen M.; Halpern, Jules P.; Jenkins, Edward B.; Casebeer, Darrin

2007-11-01

This is the second of two papers reporting observations and analysis of the unusually bright (mb=14.4), luminous (MB=-25.5), nearby (z=0.192) narrow-line quasar PHL 1811. The first paper reported that PHL 1811 is intrinsically X-ray-weak and presented a spectral energy distribution (SED). Here we present HST STIS optical and UV spectra, and ground-based optical spectra. The optical and UV line emission is very unusual. There is no evidence for forbidden or semiforbidden lines. The near-UV spectrum is dominated by very strong Fe II and Fe III, and unusual low-ionization lines such as Na I D and Ca II H and K are observed. High-ionization lines are very weak; C IV has an equivalent width of 6.6 Å, a factor of ~5 smaller than measured from quasar composite spectra. An unusual feature near 1200 Å can be deblended in terms of Lyα, N V, Si II, and C III* using the blueshifted C IV profile as a template. Photoionization modeling shows that the unusual line emission can be explained qualitatively by the unusually soft SED. Principally, a low gas temperature results in inefficient emission of collisionally excited lines, including the semiforbidden lines generally used as density diagnostics. The emission resembles that of high-density gas; in both cases this is a consequence of inefficient cooling. PHL 1811 is very unusual, but we note that quasar surveys may be biased against finding similar objects. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with proposal 9181. Based on observations obtained at Kitt Peak National Observatory, a division of the National Optical Astronomy Observatories, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.

THE HERSCHEL DIGIT SURVEY OF WEAK-LINE T TAURI STARS: IMPLICATIONS FOR DISK EVOLUTION AND DISSIPATION

International Nuclear Information System (INIS)

Cieza, Lucas A.; Olofsson, Johan; Henning, Thomas; Harvey, Paul M.; Evans, Neal J. II; Najita, Joan; Merín, Bruno; Liebhart, Armin; Güdel, Manuel; Augereau, Jean-Charles; Pinte, Christophe

2013-01-01

As part of the 'Dust, Ice, and Gas In Time (DIGIT)' Herschel Open Time Key Program, we present Herschel photometry (at 70, 160, 250, 350, and 500 μm) of 31 weak-line T Tauri star (WTTS) candidates in order to investigate the evolutionary status of their circumstellar disks. Of the stars in our sample, 13 had circumstellar disks previously known from infrared observations at shorter wavelengths, while 18 of them had no previous evidence for a disk. We detect a total of 15 disks as all previously known disks are detected at one or more Herschel wavelengths and two additional disks are identified for the first time. The spectral energy distributions (SEDs) of our targets seem to trace the dissipation of the primordial disk and the transition to the debris disk regime. Of the 15 disks, 7 appear to be optically thick primordial disks, including 2 objects with SEDs indistinguishable from those of typical Classical T Tauri stars, 4 objects that have significant deficit of excess emission at all IR wavelengths, and 1 'pre-transitional' object with a known gap in the disk. Despite their previous WTTS classification, we find that the seven targets in our sample with optically thick disks show evidence for accretion. The remaining eight disks have weaker IR excesses similar to those of optically thin debris disks. Six of them are warm and show significant 24 μm Spitzer excesses, while the last two are newly identified cold debris-like disks with photospheric 24 μm fluxes, but significant excess emission at longer wavelengths. The Herschel photometry also places strong constraints on the non-detections, where systems with F 70 /F 70,* ∼> 5-15 and L disk /L * ∼> 10 –3 to 10 –4 can be ruled out. We present preliminary models for both the optically thick and optically thin disks and discuss our results in the context of the evolution and dissipation of circumstellar disks.

THE HERSCHEL DIGIT SURVEY OF WEAK-LINE T TAURI STARS: IMPLICATIONS FOR DISK EVOLUTION AND DISSIPATION

Energy Technology Data Exchange (ETDEWEB)

Cieza, Lucas A. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Olofsson, Johan; Henning, Thomas [Max Planck Institute fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Harvey, Paul M.; Evans, Neal J. II [Department of Astronomy, University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712-1205 (United States); Najita, Joan [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 86719 (United States); Merin, Bruno [Herschel Science Centre, European Space Astronomy Centre, ESA, P.O. Box 78, E-28691 Villanueva de la Canada, Madrid (Spain); Liebhart, Armin; Guedel, Manuel [Department of Astronomy, University of Vienna, Tuerkenschanzstr. 17, A-1180 Vienna (Austria); Augereau, Jean-Charles; Pinte, Christophe, E-mail: lcieza@ifa.hawaii.edu [UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d' Astrophysique (IPAG) UMR 5274, BP 53, F-38041 Grenoble cedex 9 (France)

2013-01-10

As part of the 'Dust, Ice, and Gas In Time (DIGIT)' Herschel Open Time Key Program, we present Herschel photometry (at 70, 160, 250, 350, and 500 {mu}m) of 31 weak-line T Tauri star (WTTS) candidates in order to investigate the evolutionary status of their circumstellar disks. Of the stars in our sample, 13 had circumstellar disks previously known from infrared observations at shorter wavelengths, while 18 of them had no previous evidence for a disk. We detect a total of 15 disks as all previously known disks are detected at one or more Herschel wavelengths and two additional disks are identified for the first time. The spectral energy distributions (SEDs) of our targets seem to trace the dissipation of the primordial disk and the transition to the debris disk regime. Of the 15 disks, 7 appear to be optically thick primordial disks, including 2 objects with SEDs indistinguishable from those of typical Classical T Tauri stars, 4 objects that have significant deficit of excess emission at all IR wavelengths, and 1 'pre-transitional' object with a known gap in the disk. Despite their previous WTTS classification, we find that the seven targets in our sample with optically thick disks show evidence for accretion. The remaining eight disks have weaker IR excesses similar to those of optically thin debris disks. Six of them are warm and show significant 24 {mu}m Spitzer excesses, while the last two are newly identified cold debris-like disks with photospheric 24 {mu}m fluxes, but significant excess emission at longer wavelengths. The Herschel photometry also places strong constraints on the non-detections, where systems with F {sub 70}/F {sub 70,*} {approx}> 5-15 and L {sub disk}/L {sub *} {approx}> 10{sup -3} to 10{sup -4} can be ruled out. We present preliminary models for both the optically thick and optically thin disks and discuss our results in the context of the evolution and dissipation of circumstellar disks.

A survey of infrared continuum versus line radiation from metal halide lamps

International Nuclear Information System (INIS)

Kato, M; Herd, M T; Lawler, J E

2008-01-01

Near-infrared radiation (near-IR) losses from the arcs of six commercial metal halide high intensity discharge (MH-HID) lamps with various power levels and with both Na/Sc and rare earth doses were surveyed in this paper. A radiometrically calibrated Fourier transform infrared spectrometer was used. Lamps with rare earth doses have appreciably better color rendering indices (CRIs) than lamps with Na/Sc doses. The ratios of near-IR continuum emission over near-IR line emission from these six lamps were compared. The near-IR continuum dominates near-IR losses from lamps with rare earth doses and the continuum is significant, but not dominant, from lamps with Na/Sc doses. There was no strong dependence of this ratio on input power or color temperature (T c ). Total near-IR losses were estimated using absolutely calibrated, horizontal irradiance measurements. Estimated total near-IR losses were correlated with CRI. The lamps with rare earth doses yield the best CRIs, but have appreciably higher near-IR losses due primarily to continuum processes. One of these rare earth MH-HID lamps was used in a more detailed study of the microscopic physics of the continuum mechanism (Herd M T and Lawler E 2007 J. Phys. D: Appl. Phys. 40 3386)

Trace metals analysis in estuarine and seawater by ICP-MS using on line preconcentration and matrix elimination with chelating resin.

Science.gov (United States)

Nicolaı, M; Rosin, C; Tousset, N; Nicolai, Y

1999-09-13

The main difficulties of trace metals analysis in estuarine and seawater stem from their very low concentration (mug/l to sub-mug/l), and, by contrast, the high salt content (up to 38 g/l in the Mediterranean Sea). ICP-MS allows multi-elemental analysis and offers great sensitivity, but may be strongly affected by matrix effects induced by high salt contents (> 1 g/l). To perform trace metals analysis both in riverine, estuarine and seawater, we have developed a hyphenated method: ion chelation chromatography coupled on-line with ICP-MS. Iminodiacetate resin, Metpac CC-1 (Dionex), was used to concentrate most of the trace metals, and to separate them from alkaline and alkaline-earth metals. Behaviour of 17 elements (Pb, Cu, Cd, Ni, U, Cr, Mn, Al, Co, Ga, In, Zn, V, Tl, Bi, Ag and Sn) towards the resin was qualitatively investigated. A method validation, partly derived from AFNOR standard XPT 90-210, was carried out on 12 elements (Pb, Cu, Cd, Ni, U, Cr, Mn, Al, Co, Ga, Bi and In). Replicate measurements of multi-elemental standard solutions were used to check linearity, and to determine repeatability and detection limits. Method accuracy was then assessed by analysing two certified materials: a synthetic freshwater (SRM 1643d), and a natural filtered coastal seawater (NRCC CASS-3). An application assay of natural samples from the Rhône river (France) was eventually carried out, and the analytical results were found to be consistent with previous works.

History of Weak Interactions

Science.gov (United States)

Lee, T. D.

1970-07-01

While the phenomenon of beta-decay was discovered near the end of the last century, the notion that the weak interaction forms a separate field of physical forces evolved rather gradually. This became clear only after the experimental discoveries of other weak reactions such as muon-decay, muon-capture, etc., and the theoretical observation that all these reactions can be described by approximately the same coupling constant, thus giving rise to the notion of a universal weak interaction. Only then did one slowly recognize that the weak interaction force forms an independent field, perhaps on the same footing as the gravitational force, the electromagnetic force, and the strong nuclear and sub-nuclear forces.

Development and testing of on-line analytical instrumentation for alkali and heavy metal release in pressurised conversion processes

Energy Technology Data Exchange (ETDEWEB)

Hernberg, R; Haeyrinen, V; Oikari, R [Tampere Univ. of Technology (Finland)

1997-10-01

The purpose of the project is to demonstrate in industrial conditions and further develop the continuous alkali measurement method plasma excited alkali resonance line spectroscopy (PEARLS) developed at Tampere University of Technology (TUT). The demonstration takes place in joint measuring campaigns, where two other continuous alkali measurement methods, ELIF and surface ionisation, are being simultaneously demonstrated. A modification of PEARLS will also be developed for the continuous measurement of heavy metal concentrations. A market study of continuous measuring techniques for alkali and heavy metals is further part of the project. The method will be demonstrated in two pressurised fluidised bed combustion facilities. One of these is the 10 MW PCFB of Foster Wheeler Energia Oy in Karhula. The second one is yet to be decided. The first measuring campaign is scheduled for the spring of 1997 in Karhula. In 1996 the group at TUT participated in the performance of a market study regarding continuous measuring techniques for alkali and heavy metal concentrations. A draft report was submitted to and approved by the EC. Development work on PEARLS in 1996 has centered around the construction of a calibration device for alkali measurements. The device can be used by all three measuring techniques in the project to check readings against a known alkali concentration at controlled and known conditions. In 1996 PEARLS was applied for alkali measurement at several pressurised combustion installations of laboratory and industrial pilot scale

THE KINEMATICS OF THE NEBULAR SHELLS AROUND LOW MASS PROGENITORS OF PNe WITH LOW METALLICITY

Energy Technology Data Exchange (ETDEWEB)

Pereyra, Margarita; López, José Alberto; Richer, Michael G., E-mail: mally@astrosen.unam.mx, E-mail: jal@astrosen.unam.mx, E-mail: richer@astrosen.unam.mx [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 106, C.P. 22800 Ensenada, BC, México (Mexico)

2016-03-15

We analyze the internal kinematics of 26 planetary nebulae (PNe) with low metallicity that appear to derive from progenitor stars of the lowest masses, including the halo PN population. Based upon spatially resolved, long-slit, echelle spectroscopy drawn from the San Pedro Mártir Kinematic Catalog of PNe, we characterize the kinematics of these PNe measuring their global expansion velocities based upon the largest sample used to date for this purpose. We find kinematics that follow the trends observed and predicted in other studies, but also find that most of the PNe studied here tend to have expansion velocities less than 20 km s{sup −1} in all of the emission lines considered. The low expansion velocities that we observe in this sample of low metallicity PNe with low mass progenitors are most likely a consequence of a weak central star (CS) wind driving the kinematics of the nebular shell. This study complements previous results that link the expansion velocities of the PN shells with the characteristics of the CS.

Weakly nonlocal symplectic structures, Whitham method and weakly nonlocal symplectic structures of hydrodynamic type

International Nuclear Information System (INIS)

Maltsev, A Ya

2005-01-01

We consider the special type of field-theoretical symplectic structures called weakly nonlocal. The structures of this type are, in particular, very common for integrable systems such as KdV or NLS. We introduce here the special class of weakly nonlocal symplectic structures which we call weakly nonlocal symplectic structures of hydrodynamic type. We investigate then the connection of such structures with the Whitham averaging method and propose the procedure of 'averaging' the weakly nonlocal symplectic structures. The averaging procedure gives the weakly nonlocal symplectic structure of hydrodynamic type for the corresponding Whitham system. The procedure also gives 'action variables' corresponding to the wave numbers of m-phase solutions of the initial system which give the additional conservation laws for the Whitham system

Pair potentials in liquid metals

International Nuclear Information System (INIS)

Faber, T.E.

1980-01-01

The argument which justifies the use of a pair potential to describe the structure-dependent term in the energy of liquid metals is briefly reviewed. Because there is an additional term in the energy which depends upon volume rather than structure, and because the pair potential itself is volume-dependent, the relationship between pair potential and observable properties such as pressure, bulk modulus and pair distribution function is more complicated for liquid metals than it is for molecular liquids. Perhaps for this reason, the agreement between pair potentials inferred from observable properties and pair potentials calculated by means of pseudo-potential theory is still far from complete. The pair potential concept is applicable only to simple liquid metals, in which the electron-ion interaction is weak. No attempt is made to discuss liquid transition and rare-earth metals, which are not simple in this sense. (author)

Transition from metal-ligand bonding to halogen bonding involving a metal as halogen acceptor a study of Cu, Ag, Au, Pt, and Hg complexes

Science.gov (United States)

Oliveira, Vytor; Cremer, Dieter

2017-08-01

Utilizing all-electron Dirac-exact relativistic calculations with the Normalized Elimination of the Small Component (NESC) method and the local vibrational mode approach, the transition from metal-halide to metal halogen bonding is determined for Au-complexes interacting with halogen-donors. The local stretching force constants of the metal-halogen interactions reveal a smooth transition from weak non-covalent halogen bonding to non-classical 3-center-4-electron bonding and finally covalent metal-halide bonding. The strongest halogen bonds are found for dialkylaurates interacting with Cl2 or FCl. Differing trends in the intrinsic halogen-metal bond strength, the binding energy, and the electrostatic potential are explained.

Sequential injection on-line matrix removal and trace metal preconcentration using a PTFE beads packed column as demonstrated for the determination of cadmium by electrothermal atomic absorption spectrometry

DEFF Research Database (Denmark)

Wang, Jianhua; Hansen, Elo Harald

2002-01-01

A sequential injection (SI) on-line matrix removal and trace metal preconcentration procedure by using a novel microcolumn packed with PTFE beads is described, and demonstrated for trace cadmium analysis with detection by electrothermal atomic absorption spectrometry (ETAAS). The analyte...

Optimal multi-dimensional poverty lines: The state of poverty in Iraq

Science.gov (United States)

Ameen, Jamal R. M.

2017-09-01

Poverty estimation based on calories intake is unrealistic. The established concept of multidimensional poverty has methodological weaknesses in the treatment of different dimensions and there is disagreement in methods of combining them into a single poverty line. This paper introduces a methodology to estimate optimal multidimensional poverty lines and uses the Iraqi household socio-economic survey data of 2012 to demonstrate the idea. The optimal poverty line for Iraq is found to be 170.5 Thousand Iraqi Dinars (TID).

Characterization of the Goubau line for testing beam diagnostic instruments

Science.gov (United States)

Kim, S. Y.; Stulle, F.; Sung, C. K.; Yoo, K. H.; Seok, J.; Moon, K. J.; Choi, C. U.; Chung, Y.; Kim, G.; Woo, H. J.; Kwon, J.; Lee, I. G.; Choi, E. M.; Chung, M.

2017-12-01

One of the main characteristics of the Goubau line is that it supports a low-loss, non-radiated surface wave guided by a dielectric-coated metal wire. The dominant mode of the surface wave along the Goubau line is a TM01 mode, which resembles the pattern of the electromagnetic fields induced in the metallic beam pipe when the charged particle beam passes through it. Therefore, the Goubau line can be used for the preliminary bench test and performance optimization of the beam diagnostic instruments without requiring charged particle beams from the accelerators. In this paper, we discuss the basic properties of the Goubau line for testing beam diagnostic instruments and present the initial test results for button-type beam position monitors (BPMs). The experimental results are consistent with the theoretical estimations, which indicates that Goubau line allows effective testing of beam diagnostic equipment.

Magnus force and inertia properties of magnetic vortices in weak ferromagnets

International Nuclear Information System (INIS)

Zvezdin, A.K.; Zvezdin, K.A.

2010-01-01

The question of the Magnus force in weak ferromagnets acting on magnetic vortices (Bloch lines), within domain boundary has been investigated and the general formula of the Magnus force has been derived. It is shown that the Magnus force is non-zero in most types domain boundaries and determined by the average sublattice magnetization, Dzyaloshinskii coupling constants and exchange interaction between the sublattices. Generalized expressions have been obtained for the effective Langrangian and Rayleigh functions in weak ferromagnets allowing for their vortex structure. The mass of a vortex was considered and the value m * ∼ 10 -14 g/cm was obtained for YFeO 3 . The dynamic bending of the domain boundary in the presence of a moving vortex has been analyzed. A formula has been obtained, which describes the dependence of the vortex velocity in a motionless domain boundary upon the magnetic-field.

Weak interactions

International Nuclear Information System (INIS)

Bjorken, J.D.

1978-01-01

Weak interactions are studied from a phenomenological point of view, by using a minimal number of theoretical hypotheses. Charged-current phenomenology, and then neutral-current phenomenology are discussed. This all is described in terms of a global SU(2) symmetry plus an electromagnetic correction. The intermediate-boson hypothesis is introduced and lower bounds on the range of the weak force are inferred. This phenomenology does not yet reconstruct all the predictions of the conventional SU(2)xU(1) gauge theory. To do that requires an additional assumption of restoration of SU(2) symmetry at asymptotic energies

Systematic review: role of acid, weakly acidic and weakly alkaline reflux in gastro-oesophageal reflux disease

NARCIS (Netherlands)

Boeckxstaens, G. E.; Smout, A.

2010-01-01

The importance of weakly acidic and weakly alkaline reflux in gastro-oesophageal reflux disease (GERD) is gaining recognition. To quantify the proportions of reflux episodes that are acidic (pH <4), weakly acidic (pH 4-7) and weakly alkaline (pH >7) in adult patients with GERD, and to evaluate their

Dynamic analysis and vibration testing of CFRP drive-line system used in heavy-duty machine tool

OpenAIRE

Mo Yang; Lin Gui; Yefa Hu; Guoping Ding; Chunsheng Song

2018-01-01

Low critical rotary speed and large vibration in the metal drive-line system of heavy-duty machine tool affect the machining precision seriously. Replacing metal drive-line with the CFRP drive-line can effectively solve this problem. Based on the composite laminated theory and the transfer matrix method (TMM), this paper puts forward a modified TMM to analyze dynamic characteristics of CFRP drive-line system. With this modified TMM, the CFRP drive-line of a heavy vertical miller is analyzed. ...

Weakly infinite-dimensional spaces

International Nuclear Information System (INIS)

Fedorchuk, Vitalii V

2007-01-01

In this survey article two new classes of spaces are considered: m-C-spaces and w-m-C-spaces, m=2,3,...,∞. They are intermediate between the class of weakly infinite-dimensional spaces in the Alexandroff sense and the class of C-spaces. The classes of 2-C-spaces and w-2-C-spaces coincide with the class of weakly infinite-dimensional spaces, while the compact ∞-C-spaces are exactly the C-compact spaces of Haver. The main results of the theory of weakly infinite-dimensional spaces, including classification via transfinite Lebesgue dimensions and Luzin-Sierpinsky indices, extend to these new classes of spaces. Weak m-C-spaces are characterised by means of essential maps to Henderson's m-compacta. The existence of hereditarily m-strongly infinite-dimensional spaces is proved.

Acute muscular weakness in children

Directory of Open Access Journals (Sweden)

Ricardo Pablo Javier Erazo Torricelli

Full Text Available ABSTRACT Acute muscle weakness in children is a pediatric emergency. During the diagnostic approach, it is crucial to obtain a detailed case history, including: onset of weakness, history of associated febrile states, ingestion of toxic substances/toxins, immunizations, and family history. Neurological examination must be meticulous as well. In this review, we describe the most common diseases related to acute muscle weakness, grouped into the site of origin (from the upper motor neuron to the motor unit. Early detection of hyperCKemia may lead to a myositis diagnosis, and hypokalemia points to the diagnosis of periodic paralysis. Ophthalmoparesis, ptosis and bulbar signs are suggestive of myasthenia gravis or botulism. Distal weakness and hyporeflexia are clinical features of Guillain-Barré syndrome, the most frequent cause of acute muscle weakness. If all studies are normal, a psychogenic cause should be considered. Finding the etiology of acute muscle weakness is essential to execute treatment in a timely manner, improving the prognosis of affected children.

Optical and electrical experiments at some transition-metal oxide foil-electrolyte interfaces

International Nuclear Information System (INIS)

Sari, S.O.; Ahlgren, W.L.

1977-01-01

Metal-oxide layers formed from transition-metal foils oxidized by heating in air have been examined for their photoelectrolytic response. The metals examined are Y, Ti, Zr, Hf, V, Nb, Ta, Mo, W, and Pt. Weak photoeffects are observed for oxide layers of all of these metals. Sizable light-dependent oxygen gas evolution rates are found in Ti and also in W oxides. The spectral dependence of the oxygen response in these compounds is investigated, and interpretation is given of these experiments

Identification of MgII Absorption Line Systems from SDSS Quasar ...

Indian Academy of Sciences (India)

Motivation. The quasar absorption lines are crucial to our understanding of the Universe since the absorption lines provide a wealth of information on the gaseous Universe from high redshift to present day. The absorption lines can also allow us to probe the metallicity and ionization state of the gas (Wild et al. 2008).

Neutron-diffraction investigations of flux-lines in superconductors

Energy Technology Data Exchange (ETDEWEB)

Forgan, E M [Birmingham Univ. (United Kingdom); Lee, S L [Saint Andrews Univ. (United Kingdom); McKPaul, D [Warwick Univ., Coventry (United Kingdom); Mook, H A [Oak Ridge National Lab., TN (United States); Cubitt, R [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

1997-04-01

SANS has proved an extremely useful tool for investigating flux-line structures within the bulk of superconductors. With high-T{sub c} materials, the scattered intensities are weak, but careful measurements are giving important new information about flux lattices, flux pinning and flux-lattice melting. (author). 10 refs.

Weak openness and almost openness

Directory of Open Access Journals (Sweden)

David A. Rose

1984-01-01

Full Text Available Weak openness and almost openness for arbitrary functions between topological spaces are defined as duals to the weak continuity of Levine and the almost continuity of Husain respectively. Independence of these two openness conditions is noted and comparison is made between these and the almost openness of Singal and Singal. Some results dual to those known for weak continuity and almost continuity are obtained. Nearly almost openness is defined and used to obtain an improved link from weak continuity to almost continuity.

Weak values in collision theory

Science.gov (United States)

de Castro, Leonardo Andreta; Brasil, Carlos Alexandre; Napolitano, Reginaldo de Jesus

2018-05-01

Weak measurements have an increasing number of applications in contemporary quantum mechanics. They were originally described as a weak interaction that slightly entangled the translational degrees of freedom of a particle to its spin, yielding surprising results after post-selection. That description often ignores the kinetic energy of the particle and its movement in three dimensions. Here, we include these elements and re-obtain the weak values within the context of collision theory by two different approaches, and prove that the results are compatible with each other and with the results from the traditional approach. To provide a more complete description, we generalize weak values into weak tensors and use them to provide a more realistic description of the Stern-Gerlach apparatus.

Electromagnetic current in weak interactions

International Nuclear Information System (INIS)

Ma, E.

1983-01-01

In gauge models which unify weak and electromagnetic interactions, the weak neutral-current interaction also involves the electromagnetic current. The exact nature of such a component can be explored using e + e - experimental data. In recent years, the existence of a new component of the weak interaction has become firmly established, i.e., the neutral-current interaction. As such, it competes with the electromagnetic interaction whenever the particles involved are also charged, but at a very much lower rate because its effective strength is so small. Hence neutrino processes are best for the detection of the neutral-current interaction. However, in any gauge model which unifies weak and electromagnetic interactions, the weak neutral-current interaction also involves the electromagnetic current

Coexistence of weak ferromagnetism and ferroelectricity in the high pressure LiNbO3-type phase of FeTiO3.

Science.gov (United States)

Varga, T; Kumar, A; Vlahos, E; Denev, S; Park, M; Hong, S; Sanehira, T; Wang, Y; Fennie, C J; Streiffer, S K; Ke, X; Schiffer, P; Gopalan, V; Mitchell, J F

2009-07-24

We report the magnetic and electrical characteristics of polycrystalline FeTiO_{3} synthesized at high pressure that is isostructural with acentric LiNbO_{3} (LBO). Piezoresponse force microscopy, optical second harmonic generation, and magnetometry demonstrate ferroelectricity at and below room temperature and weak ferromagnetism below approximately 120 K. These results validate symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and weak ferromagnetism in a series of transition metal titanates crystallizing in the LBO structure.

Nebular and auroral emission lines of [Cl III] in the optical spectra of planetary nebulae.

Science.gov (United States)

Keenan, F P; Aller, L H; Ramsbottom, C A; Bell, K L; Crawford, F L; Hyung, S

2000-04-25

Electron impact excitation rates in Cl III, recently determined with the R-matrix code, are used to calculate electron temperature (T(e)) and density (N(e)) emission line ratios involving both the nebular (5517.7, 5537.9 A) and auroral (8433.9, 8480.9, 8500.0 A) transitions. A comparison of these results with observational data for a sample of planetary nebulae, obtained with the Hamilton Echelle Spectrograph on the 3-m Shane Telescope, reveals that the R(1) = I(5518 A)/I(5538 A) intensity ratio provides estimates of N(e) in excellent agreement with the values derived from other line ratios in the echelle spectra. This agreement indicates that R(1) is a reliable density diagnostic for planetary nebulae, and it also provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. However the [Cl iii] 8433.9 A line is found to be frequently blended with a weak telluric emission feature, although in those instances when the [Cl iii] intensity may be reliably measured, it provides accurate determinations of T(e) when ratioed against the sum of the 5518 and 5538 A line fluxes. Similarly, the 8500.0 A line, previously believed to be free of contamination by the Earth's atmosphere, is also shown to be generally blended with a weak telluric emission feature. The [Cl iii] transition at 8480.9 A is found to be blended with the He i 8480.7 A line, except in planetary nebulae that show a relatively weak He i spectrum, where it also provides reliable estimates of T(e) when ratioed against the nebular lines. Finally, the diagnostic potential of the near-UV [Cl iii] lines at 3344 and 3354 A is briefly discussed.

On-line liquid phase micro-extraction based on drop-in-plug sequential injection lab-at-valve platform for metal determination

Energy Technology Data Exchange (ETDEWEB)

Mitani, Constantina [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54124 (Greece); Anthemidis, Aristidis N., E-mail: anthemid@chem.auth.gr [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54124 (Greece)

2013-04-10

Highlights: ► Drop-in-plug micro-extraction based on SI-LAV platform for metal preconcentration. ► Automatic liquid phase micro-extraction coupled with FAAS. ► Organic solvents with density higher than water are used. ► Lead determination in environmental water and urine samples. -- Abstract: A novel automatic on-line liquid phase micro-extraction method based on drop-in-plug sequential injection lab-at-valve (LAV) platform was proposed for metal preconcentration and determination. A flow-through micro-extraction chamber mounted at the selection valve was adopted without the need of sophisticated lab-on-valve components. Coupled to flame atomic absorption spectrometry (FAAS), the potential of this lab-at-valve scheme is demonstrated for trace lead determination in environmental and biological water samples. A hydrophobic complex of lead with ammonium pyrrolidine dithiocarbamate (APDC) was formed on-line and subsequently extracted into an 80 μL plug of chloroform. The extraction procedure was performed by forming micro-droplets of aqueous phase into the plug of the extractant. All critical parameters that affect the efficiency of the system were studied and optimized. The proposed method offered good performance characteristics and high preconcentration ratios. For 10 mL sample consumption an enhancement factor of 125 was obtained. The detection limit was 1.8 μg L{sup −1} and the precision expressed as relative standard deviation (RSD) at 50.0 μg L{sup −1} of lead was 2.9%. The proposed method was evaluated by analyzing certified reference materials and applied for lead determination in natural waters and urine samples.

Anisotropic shift of the irreversibility line by neutron irradiation

International Nuclear Information System (INIS)

Sauerzopf, F.M.; Wiesinger, H.P.; Weber, H.W.; Crabtree, G.W.; Frischherz, M.C.; Kirk, M.A.

1991-09-01

The irreversibility line of high-T c superconductors is shifted considerably by irradiating the material with fast neutrons. The anisotropic and non-monotonous shift is qualitatively explained by a simple model based on an interaction between three pinning mechanisms, the intrinsic pinning by the ab-planes, the weak pinning by the pre-irradiation defect structure, and strong pinning by neutron induced defect cascades. A correlation between the cascade density and the position of the irreversibility line is observed

Effects of Weak Intermolecular Interactions on the Molecular Isomerism of Tricobalt Metal Chains

International Nuclear Information System (INIS)

Poulsen, R.; Overgaard, J.; Schulman, A.; Stergaard, C.; Murillo, C.; Spackman, M.; Iversen, B.

2009-01-01

Depending on the number of interstitial solvent molecules, n, crystals of the linear chain compound Co3(dipyridylamide)4Cl2·nCH2Cl2 adopt either symmetrical or unsymmetrical metal chain structures. We explore here the possible reasons for such behavior using Hirshfeld surface analysis of intermolecular interactions as well as the charge density determined from 100(1) K X-ray diffraction data on the unsymmetrical complex Co3(dipyridylamide)4Cl2·2.11CH2Cl2, u-1, and crystal structures of u-1 determined from single crystal synchrotron X-ray diffraction data at 20, 150, and 300 K. The new crystal structures are compared with previous structural results on a crystal with slightly different solvent content. This change in solvent content only affects the bond distances to atom Co(3), which are also strongly affected by temperature changes due to a spin crossover transition. Large differences in intermolecular interactions are revealed by the Hirshfeld surface analysis between symmetrical (s-1) and unsymmetrical (u-1) crystal solvates, suggesting that the molecular isomerism is strongly influenced by crystal packing effects. Topological analysis of the static electron density of u-1 suggests that there is direct metal-metal bonding for both the shorter Co(1)-Co(2) and the longer Co(2)-Co(3) contact. The approximate description of the system as a (Co2)2+-dimer and an isolated Co2+-ion is reflected in the character of the metal-ligand interactions, which are more ionic for the isolated Co(3) atom, and the topological charges Co(1)+0.50, Co(2)+0.77, and Co(3)+1.36. The two termini of u-1 are found to be very different, both in terms of structural surroundings as well as topology. The central Co(2) atom is similar to a cobalt atom in a tetragonally distorted octahedral environment resulting in preferred occupancy in the t2g orbitals. The Co(1) atom has significant deformation in the xz and yz planes (z along the chain axis, x and y toward ligands) reflecting covalent

On-line interconversion of [15O]O2 and [15O]CO2 via metal oxide by isotopic exchange

International Nuclear Information System (INIS)

Iwata, Ren; Ido, Tatsuo; Fujisawa, Yoshiki; Yamazaki, Shigeki

1988-01-01

A novel method has been developed for the on-line production of 15 O-labelled gases. The 15 O exchange reactions between O 2 and CO 2 assisted by a metal oxide catalyst were successfully applied to on-line interconversion of [ 15 O]O 2 and [ 15 O]CO 2 with Hopcalite II(CuO 40% and MnO 2 60%). The conversion reactions were optimized as to the reaction temperature, the amount of the catalyst, and the flow rate of a gas added for oxygen exchange. [ 15 O]O 2 was converted to [ 15 O]CO 2 in a 80% yield with 0.7 g of Hopcalite II and 100 mL/min of CO 2 at 500 0 C, and [ 15 O]CO 2 to [ 15 O]O 2 in 70% with 100 mL/min of O 2 at 650 0 C. The radiochemical purities of the 15 O-labelled gases converted under the optimal conditions were high enough for clinical studies using the standard dilution and inhalation procedures. (author)

Weak Defect Identification for Centrifugal Compressor Blade Crack Based on Pressure Sensors and Genetic Algorithm.

Science.gov (United States)

Li, Hongkun; He, Changbo; Malekian, Reza; Li, Zhixiong

2018-04-19

The Centrifugal compressor is a piece of key equipment for petrochemical factories. As the core component of a compressor, the blades suffer periodic vibration and flow induced excitation mechanism, which will lead to the occurrence of crack defect. Moreover, the induced blade defect usually has a serious impact on the normal operation of compressors and the safety of operators. Therefore, an effective blade crack identification method is particularly important for the reliable operation of compressors. Conventional non-destructive testing and evaluation (NDT&E) methods can detect the blade defect effectively, however, the compressors should shut down during the testing process which is time-consuming and costly. In addition, it can be known these methods are not suitable for the long-term on-line condition monitoring and cannot identify the blade defect in time. Therefore, the effective on-line condition monitoring and weak defect identification method should be further studied and proposed. Considering the blade vibration information is difficult to measure directly, pressure sensors mounted on the casing are used to sample airflow pressure pulsation signal on-line near the rotating impeller for the purpose of monitoring the blade condition indirectly in this paper. A big problem is that the blade abnormal vibration amplitude induced by the crack is always small and this feature information will be much weaker in the pressure signal. Therefore, it is usually difficult to identify blade defect characteristic frequency embedded in pressure pulsation signal by general signal processing methods due to the weakness of the feature information and the interference of strong noise. In this paper, continuous wavelet transform (CWT) is used to pre-process the sampled signal first. Then, the method of bistable stochastic resonance (SR) based on Woods-Saxon and Gaussian (WSG) potential is applied to enhance the weak characteristic frequency contained in the pressure

Weak interactions with nuclei

International Nuclear Information System (INIS)

Walecka, J.D.

1983-01-01

Nuclei provide systems where the strong, electomagnetic, and weak interactions are all present. The current picture of the strong interactions is based on quarks and quantum chromodynamics (QCD). The symmetry structure of this theory is SU(3)/sub C/ x SU(2)/sub W/ x U(1)/sub W/. The electroweak interactions in nuclei can be used to probe this structure. Semileptonic weak interactions are considered. The processes under consideration include beta decay, neutrino scattering and weak neutral-current interactions. The starting point in the analysis is the effective Lagrangian of the Standard Model

Bayesian Markov Chain Monte Carlo inversion for weak anisotropy parameters and fracture weaknesses using azimuthal elastic impedance

Science.gov (United States)

Chen, Huaizhen; Pan, Xinpeng; Ji, Yuxin; Zhang, Guangzhi

2017-08-01

A system of aligned vertical fractures and fine horizontal shale layers combine to form equivalent orthorhombic media. Weak anisotropy parameters and fracture weaknesses play an important role in the description of orthorhombic anisotropy (OA). We propose a novel approach of utilizing seismic reflection amplitudes to estimate weak anisotropy parameters and fracture weaknesses from observed seismic data, based on azimuthal elastic impedance (EI). We first propose perturbation in stiffness matrix in terms of weak anisotropy parameters and fracture weaknesses, and using the perturbation and scattering function, we derive PP-wave reflection coefficient and azimuthal EI for the case of an interface separating two OA media. Then we demonstrate an approach to first use a model constrained damped least-squares algorithm to estimate azimuthal EI from partially incidence-phase-angle-stack seismic reflection data at different azimuths, and then extract weak anisotropy parameters and fracture weaknesses from the estimated azimuthal EI using a Bayesian Markov Chain Monte Carlo inversion method. In addition, a new procedure to construct rock physics effective model is presented to estimate weak anisotropy parameters and fracture weaknesses from well log interpretation results (minerals and their volumes, porosity, saturation, fracture density, etc.). Tests on synthetic and real data indicate that unknown parameters including elastic properties (P- and S-wave impedances and density), weak anisotropy parameters and fracture weaknesses can be estimated stably in the case of seismic data containing a moderate noise, and our approach can make a reasonable estimation of anisotropy in a fractured shale reservoir.

Desgin of On-line Monitoring Device for MOA (Metal Oxide Arrestor Based on FPGA and C8051F

Directory of Open Access Journals (Sweden)

Xiaotong YAO

2014-10-01

Full Text Available Monitoring of metal oxide surge arresters (MOA due to aging, moisture and other components cause increased resistive current. Through a lot of practices, it has been proved that in the early days, MOA insulation damage and current increase is not obvious. The accurate working conditions of the MOA are also not obvious but it can reflect the aging or moisture of MOA. When the resistive current of the fundamental component increases, there is no increment in the harmonic components that is the general performance of a serious or moisture contamination. In the same way when the resistive current of harmonic components increases, the fundamental component is not increased and it is the general performance of aging. Therefore, this paper designed an experiment-based FPGA and C8051F-line monitoring device. This device uses resistive current as a detection target. The main monitoring parameters are the fundamental and peak value of resistive current, third harmonic content of the leakage current, phase angle difference and power consumption. Through laboratory tests, the device can be used with a network arrester line monitoring, maintenance, reduce the economic losses caused by power outages and improve the distribution network reliability.

Charge transfer and redistribution at interfaces between metals and 2D materials

NARCIS (Netherlands)

Bokdam, Menno

2013-01-01

Large potential steps are observed at the interfaces between metals and novel 2D materials. They can lower the work function by more than 1 eV, even when the two parts are only weakly interacting. In this thesis the transfer and redistribution of electrons in metal|2D material heterostructures are

Poisson equation for weak gravitational lensing

International Nuclear Information System (INIS)

Kling, Thomas P.; Campbell, Bryan

2008-01-01

Using the Newman and Penrose [E. T. Newman and R. Penrose, J. Math. Phys. (N.Y.) 3, 566 (1962).] spin-coefficient formalism, we examine the full Bianchi identities of general relativity in the context of gravitational lensing, where the matter and space-time curvature are projected into a lens plane perpendicular to the line of sight. From one component of the Bianchi identity, we provide a rigorous, new derivation of a Poisson equation for the projected matter density where the source term involves second derivatives of the observed weak gravitational lensing shear. We also show that the other components of the Bianchi identity reveal no new results. Numerical integration of the Poisson equation in test cases shows an accurate mass map can be constructed from the combination of a ground-based, wide-field image and a Hubble Space Telescope image of the same system

Inferring physical properties of galaxies from their emission-line spectra

Science.gov (United States)

Ucci, G.; Ferrara, A.; Gallerani, S.; Pallottini, A.

2017-02-01

We present a new approach based on Supervised Machine Learning algorithms to infer key physical properties of galaxies (density, metallicity, column density and ionization parameter) from their emission-line spectra. We introduce a numerical code (called GAME, GAlaxy Machine learning for Emission lines) implementing this method and test it extensively. GAME delivers excellent predictive performances, especially for estimates of metallicity and column densities. We compare GAME with the most widely used diagnostics (e.g. R23, [N II] λ6584/Hα indicators) showing that it provides much better accuracy and wider applicability range. GAME is particularly suitable for use in combination with Integral Field Unit spectroscopy, both for rest-frame optical/UV nebular lines and far-infrared/sub-millimeter lines arising from photodissociation regions. Finally, GAME can also be applied to the analysis of synthetic galaxy maps built from numerical simulations.

Weak C* Hopf Symmetry

OpenAIRE

Rehren, K. -H.

1996-01-01

Weak C* Hopf algebras can act as global symmetries in low-dimensional quantum field theories, when braid group statistics prevents group symmetries. Possibilities to construct field algebras with weak C* Hopf symmetry from a given theory of local observables are discussed.

Improved documentation of spectral lines for inductively coupled plasma emission spectrometry

Science.gov (United States)

Doidge, Peter S.

2018-05-01

An approach to improving the documentation of weak spectral lines falling near the prominent analytical lines used in inductively coupled plasma optical emission spectrometry (ICP-OES) is described. Measurements of ICP emission spectra in the regions around several hundred prominent lines, using concentrated solutions (up to 1% w/v) of some 70 elements, and comparison of the observed spectra with both recent published work and with the output of a computer program that allows calculation of transitions between the known energy levels, show that major improvements can be made in the coverage of spectral atlases for ICP-OES, with respect to "classical" line tables. It is argued that the atomic spectral data (wavelengths, energy levels) required for the reliable identification and documentation of a large majority of the weak interfering lines of the elements detectable by ICP-OES now exist, except for most of the observed lines of the lanthanide elements. In support of this argument, examples are provided from a detailed analysis of a spectral window centered on the prominent Pb II 220.353 nm line, and from a selected line-rich spectrum (W). Shortcomings in existing analyses are illustrated with reference to selected spectral interferences due to Zr. This approach has been used to expand the spectral-line library used in commercial ICP-ES instruments (Agilent 700-ES/5100-ES). The precision of wavelength measurements is evaluated in terms of the shot-noise limit, while the absolute accuracy of wavelength measurement is characterised through comparison with a small set of precise Ritz wavelengths for Sb I, and illustrated through the identification of Zr III lines; it is further shown that fractional-pixel absolute wavelength accuracies can be achieved. Finally, problems with the wavelengths and classifications of certain Au I lines are discussed.

Metal-insulator transition in 2D: the role of interactions and disorder

International Nuclear Information System (INIS)

Kastrinakis, George

2007-01-01

We present a model for the metal-insulator transition in 2D, observed in the recent years. Our starting point consists of two ingredients only, which are ubiquitous in the experiments: Coulomb interactions and weak disorder spin scattering (coming from the interfaces of the heterostructures in question). In a diagramatic approach, we predict the existence of a characteristic temperature T 0 =T 0 (n,ω H ), n being the density of carriers, and ω H the Zeeman energy, below which these systems become metallic, due to the onset of strong spin-density correlations. This is in very good agreement with experiments, and corroborates the fact that varying n and ω H are equivalent ways into/out of the metallic regime. The conductivity, calculated as a function of temperature and ω H in the metallic state, compares favorably to experiment. Moreover, we give an explicit expression for the conventional weak disorder contributions to the conductivity in the frame of our model. We comment on the nature of the transition, we calculate the specific heat of the system and we discuss the fate of the metallic state in the limit of zero temperature

An off-line automated preconcentration system with ethylenediaminetriacetate chelating resin for the determination of trace metals in seawater by high-resolution inductively coupled plasma mass spectrometry.

Science.gov (United States)

Minami, Tomoharu; Konagaya, Wataru; Zheng, Linjie; Takano, Shotaro; Sasaki, Masanobu; Murata, Rena; Nakaguchi, Yuzuru; Sohrin, Yoshiki

2015-01-07

A novel automated off-line preconcentration system for trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in seawater was developed by improving a commercially available solid-phase extraction system SPE-100 (Hiranuma Sangyo). The utilized chelating resin was NOBIAS Chelate-PA1 (Hitachi High-Technologies) with ethylenediaminetriacetic acid and iminodiacetic acid functional groups. Parts of the 8-way valve made of alumina and zirconia in the original SPE-100 system were replaced with parts made of polychlorotrifluoroethylene in order to reduce contamination of trace metals. The eluent pass was altered for the back flush elution of trace metals. We optimized the cleaning procedures for the chelating resin column and flow lines of the preconcentration system, and developed a preconcentration procedure, which required less labor and led to a superior performance compared to manual preconcentration (Sohrin et al.). The nine trace metals were simultaneously and quantitatively preconcentrated from ∼120 g of seawater, eluted with ∼15 g of 1M HNO3, and determined by HR-ICP-MS using the calibration curve method. The single-step preconcentration removed more than 99.998% of Na, K, Mg, Ca, and Sr from seawater. The procedural blanks and detection limits were lower than the lowest concentrations in seawater for Mn, Ni, Cu, and Pb, while they were as low as the lowest concentrations in seawater for Al, Fe, Co, Zn, and Cd. The accuracy and precision of this method were confirmed by the analysis of reference seawater samples (CASS-5, NASS-5, GEOTRACES GS, and GD) and seawater samples for vertical distribution in the western North Pacific Ocean. Copyright © 2014 Elsevier B.V. All rights reserved.

Bright emission lines in new Seyfert galaxies

International Nuclear Information System (INIS)

Afanasev, V.L.; Denisiuk, E.K.; Lipovetskii, V.A.; Shapovalova, A.I.

1983-01-01

Observational data are given on bright emission lines (H-alpha, H-beta, and forbidden N II, S II, and O III) for 14 recently discovered Seyfert galaxies. The investigated objects can be divided into three groups, which correspond approximately to the first (5 objects), the intermediate (4 objects), and the second (4 objects) Seyfert types. Attention is drawn to the properties of the galaxy Markaryan 1018, which has features of both the first and the second type and is distinguished by the weakness of its emission lines, which is probably due to a gas deficit. 7 references

An Energy-Stabilized Varied-Line-Space-Monochromator Undulator Beam Line for PEEM Illumination and Magnetic Circular Dichroism

International Nuclear Information System (INIS)

Warwick, Tony; McKinney, Wayne; Domning, Ed; Doran, Andrew; Padmore, Howard

2006-01-01

A new undulator beam line has been built and commissioned at the Advanced Light Source for illumination of the PEEM3 microscope. The beam line delivers high flux beams over an energy range from C1s through the transition metals to include the M edges of the magnetic rare earth elements. We present details of the optical design, and data on the performance of the zero-order tracking of the photon energy

Exotic behavior of elastic scattering differential cross-sections of weakly bound nucleus 17F at small angles

International Nuclear Information System (INIS)

Han Jianlong; Hu Zhengguo; Zhang Xueyin; Yuan Xiaohua; Xu Huagen; Qi Huirong; Wang Yue; Jia Fei; Wu Lijie; Ding Xianli; Gao Qi; Gao Hui; Bai Zhen

2006-01-01

The differential cross-sections for elastic scattering of 17 F and 17 O on 208 Pb have been measured at Radioactive Ion Beam Line at Lanzhou (RIBLL). The variation of the logarithms of differential cross-sections with the square of scattering angles shows clearly that there exists a turning point in the range of small scattering angles (6 degree-20 degree) for 17 F having exotic structure, while no turning point was observed in the 17 O elastic scattering. The experimental results have been compared with previous data. Systematical analysis on the available data seems to conclude that there is an exotic behavior of elastic scattering differential cross-sections of weakly bound nuclei with halo or skin structure as compared with that of the ordinary nuclei near stable line. Therefore the fact that the turning point of the logarithms of differential cross-sections appears at small angle for weakly bound nuclei could be used as a new probe to investigate the halo and skin phenomenon. (authors)

Impact of the uncertainty in α-captures on {sup 22}Ne on the weak s-process in massive stars

Energy Technology Data Exchange (ETDEWEB)

Nishimura, N. [Astrophysics group, EPSAM, Keele University, Keele, ST5 1BH, UK and NuGrid Project (United Kingdom); Hirschi, R. [Astrophysics group, EPSAM, Keele University, Keele, ST5 1BH, UK and Kavli IPMU (WPI), University of Tokyo, Kashiwa, 277-8583 (Japan); Pignatari, M. [NuGrid Project and Department of Physics, University of Basel, Basel, CH-4056 (Switzerland); Herwig, F. [NuGrid Project and Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P5C2 (Canada); Beard, M. [NuGrid Project and Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Imbriani, G. [Dipartiment di Scienze Fisiche, Universita di Napoli Federico II, Napoli (Italy); Görres, J.; Boer, R. J. de; Wiescher, M. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)

2014-05-02

Massive stars at solar metallicity contribute to the production of heavy elements with atomic masses between A = 60 and A = 90 via the so-called weak s-process (which takes place during core He and shell C burning phases). Furthermore, recent studies have shown that rotation boosts the s-process production in massive stars at low metallicities, with a production that may reach the barium neutron-magic peak. These results are very sensitive to neutron source and neutron poison reaction rates. For the weak s-process, the main neutron source is the reaction {sup 22}Ne(α,n){sup 25}Mg, which is in competition with {sup 22}Ne(α,γ){sup 26}Mg. The uncertainty of both rates strongly affects the nucleosynthesis predictions from stellar model calculations. In this study, we investigate the impact of the uncertainty in α-captures on {sup 22}Ne on the s-process nucleosynthesis in massive stars both at solar and at very low metallicity. For this purpose, we post-process, with the Nugrid mppnp code, non-rotating and rotating evolutionary models 25M{sub ⊙} stars at two different metallicities: Z = Z{sub ⊙} and Z = 10{sup −5}Z{sub ⊙}, respectively. Our results show that uncertainty of {sup 22}Ne(α,n){sup 25}Mg and {sup 22}Ne(α,γ){sup 26}Mg rates have a significant impact on the final elemental production especially for metal poor rotating models. Beside uncertainties in the neutron source reactions, for fast rotating massive stars at low metallicity we revisit the impact of the neutron poisoning effect by the reaction chain {sup 16}O(n,γ){sup 17}O(α,γ){sup 21}Ne, in competition with the {sup 17}O(α,n){sup 20}Ne, recycling the neutrons captured by {sup 16}O.

Weak Localization and Antilocalization in Topological Materials with Impurity Spin-Orbit Interactions

Science.gov (United States)

Hankiewicz, Ewelina M.; Culcer, Dimitrie

2017-01-01

Topological materials have attracted considerable experimental and theoretical attention. They exhibit strong spin-orbit coupling both in the band structure (intrinsic) and in the impurity potentials (extrinsic), although the latter is often neglected. In this work, we discuss weak localization and antilocalization of massless Dirac fermions in topological insulators and massive Dirac fermions in Weyl semimetal thin films, taking into account both intrinsic and extrinsic spin-orbit interactions. The physics is governed by the complex interplay of the chiral spin texture, quasiparticle mass, and scalar and spin-orbit scattering. We demonstrate that terms linear in the extrinsic spin-orbit scattering are generally present in the Bloch and momentum relaxation times in all topological materials, and the correction to the diffusion constant is linear in the strength of the extrinsic spin-orbit. In topological insulators, which have zero quasiparticle mass, the terms linear in the impurity spin-orbit coupling lead to an observable density dependence in the weak antilocalization correction. They produce substantial qualitative modifications to the magnetoconductivity, differing greatly from the conventional Hikami-Larkin-Nagaoka formula traditionally used in experimental fits, which predicts a crossover from weak localization to antilocalization as a function of the extrinsic spin-orbit strength. In contrast, our analysis reveals that topological insulators always exhibit weak antilocalization. In Weyl semimetal thin films having intermediate to large values of the quasiparticle mass, we show that extrinsic spin-orbit scattering strongly affects the boundary of the weak localization to antilocalization transition. We produce a complete phase diagram for this transition as a function of the mass and spin-orbit scattering strength. Throughout the paper, we discuss implications for experimental work, and, at the end, we provide a brief comparison with transition metal

Correlations between deformations, surface state and leak rate in metal to metal contact; Correlations entre deformations, etat de surface et debit de fuite au contact metal-metal

Energy Technology Data Exchange (ETDEWEB)

Armand, G; Lapujoulade, J; Paigne, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

The study of metal to metal contact from the stand-point of the leak rate has been carried on a copper ring located between two hard-steel flanges. The analysis of the results confirms the hysteresis phenomenon already seen. Some curves (leak rate versus force and leak rate versus true deformation) in semi-logarithmic coordinates are straight lines. Likewise some curves (electrical contact resistance versus force) in bi-logarithmic coordinates are straight lines. All these results can be understood by looking at the conductance introduced by the deformations of the micro-geometry of the surfaces in contact. Some tests carried out in rising the temperature confirm these hypothesis. (authors) [French] L'etude du contact metal-metal du point de vue debit de fuite a ete poursuivie en utilisant un anneau de cuivre place entre brides d'acier dur. L'analyse des resultats confirme le phenomene d'hysteresis deja constate, montre l'influence de l'etat de surface des brides et du joint. Certaines courbes (debit de fuite/force et debit de fuite/deformation rationnelle), en coordonnees semi-logarithmiques, sont des droites. De meme, certaines courbes (resistance de contact/force) en coordonnees bi-logarithmiques, sont des droites. Ces resultats s'interpretent en considerant la conductance produite par la deformation des microgeometries des surfaces en contact. Quelques essais d'elevation de temperature confirment ces resultats. (auteurs)

Avian mortality rates on a power line near Kampala, Uganda

African Journals Online (AJOL)

power line carried on tall metal pylons, and a smaller 33-kV line, with three conduc- tors supported on wooden poles, ... able literature on bird mortality associated with power lines (e.g. Lehman et al. 2005,. Jenkins et al. 2010, Edison .... the conductor wires would have been hard to see. Residents reported that other birds.

[Experimental analysis of finishing lines in ceramometal restorations].

Science.gov (United States)

Gascón, F; Gil, J A; Fons, A; Badal, R

1990-11-01

The preparation is the first step of any tooth reconstruction. The biological integration of the protesis is depending on the marginal adaptation (finish line of the preparation), occlusal adaptation (occlusal reduction), longevity of the restoration (retention and luting) and esthetics. The effect the two finish line of the preparation is studied using experimental design. In porcelain-fused-to-metal the finish line of the preparation in chanfer is superior at the beveled shoulder, because proportioning better marginal adaptation.

The Of emission lines near 4650 A

International Nuclear Information System (INIS)

Underhill, A.B.; Gilroy, K.K.; Hill, G.M.

1989-01-01

Rectified, normalized, high S/N intensity tracings of nine Of stars were obtained from Reticon spectra in the 4550-4800-A region. The well-known relatively sharp Of emission lines are seen to stand on pedestals of broad weak emission somewhat like the broad emission lines from WR stars. It is suggested that cascades following dielectronic recombination may be an important process driving some lines of N III, C III, and C IV into the emission of Of stars, and that the sharp Of lines come from plasma that is stationary with respect to the star. The broad emission features show an extensive low-density wind from each star. The results imply that the detection of two, more or less equal, broad jumps in the rest spectra of galaxies at about 4640 and 4686 A is more indicative of Of stars than of WR stars. 32 refs

The helium abundance in the metal-poor globular clusters M30 and NGC 6397

Energy Technology Data Exchange (ETDEWEB)

Mucciarelli, A.; Lovisi, L.; Lanzoni, B.; Ferraro, F. R. [Dipartimento di Fisica and Astronomia, Università degli Studi di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy)

2014-05-01

We present the helium abundance of the two metal-poor clusters M30 and NGC 6397. Helium estimates have been obtained by using the high-resolution spectrograph FLAMES at the European Southern Observatory Very Large Telescope and by measuring the He I line at 4471 Å in 24 and 35 horizontal branch (HB) stars in M30 and NGC 6397, respectively. This sample represents the largest data set of He abundances collected so far in metal-poor clusters. The He mass fraction turns out to be Y = 0.252 ± 0.003 (σ = 0.021) for M30 and Y = 0.241 ± 0.004 (σ = 0.023) for NGC 6397. These values are fully compatible with the cosmological abundance, thus suggesting that the HB stars are not strongly enriched in He. The small spread of the Y distributions are compatible with those expected from the observed main sequence splitting. Finally, we find a hint of a weak anticorrelation between Y and [O/Fe] in NGC 6397 in agreement with the prediction that O-poor stars are formed by (He-enriched) gas polluted by the products of hot proton-capture reactions.

Weak Solution and Weakly Uniformly Bounded Solution of Impulsive Heat Equations Containing “Maximum” Temperature

Directory of Open Access Journals (Sweden)

Oyelami, Benjamin Oyediran

2013-09-01

Full Text Available In this paper, criteria for the existence of weak solutions and uniformly weak bounded solution of impulsive heat equation containing maximum temperature are investigated and results obtained. An example is given for heat flow system with impulsive temperature using maximum temperature simulator and criteria for the uniformly weak bounded of solutions of the system are obtained.

Metal luminescence in a bright disintegrated prominence

International Nuclear Information System (INIS)

Yakovkin, N.A.; Zel'dina, M.Yu.; Rakhubovskij, A.S.; AN Ukrainskoj SSR, Kiev. Glavnaya Astronomicheskaya Observatoriya)

1975-01-01

It is found that Na, Mg, Ca, Sc, Ti, Fe, Sr, and Ba contents in a protuberance relative to the hydrogen content is about the same as in photosphere and chromosphere (except for the Na abundance). The metals are in the state of single ionization with the exception of calcium [Ca ++ ] approximately [Ca + ], strontium [Sr ++ ] = 0.5 [Sr + ], and barium [Ba ++ ] = 6Ba + , whose secondary ionization occurs from metastable states by Lsub(α)-emission in the protuberance. The Lsub(α)-emission ionizes neutral iron as well. Primary ionization of remaining metals is performed by the solar near ultraviolet. Luminescence in metal lines is provided by the photosphere emission scattering, and only H and KCa + lines are excited by electron impacts

Towards Using NMR to Screen for Spoiled Tomatoes Stored in 1,000 L, Aseptically Sealed, Metal-Lined Totes

Directory of Open Access Journals (Sweden)

Michael D. Pinter

2014-03-01

Full Text Available Nuclear magnetic resonance (NMR spectroscopy is used to track factory relevant tomato paste spoilage. It was found that spoilage in tomato paste test samples leads to longer spin lattice relaxation times T1 using a conventional low magnetic field NMR system. The increase in T1 value for contaminated samples over a five day room temperature exposure period prompted the work to be extended to the study of industry standard, 1,000 L, non-ferrous, metal-lined totes. NMR signals and T1 values were recovered from a large format container with a single-sided NMR sensor. The results of this work suggest that a handheld NMR device can be used to study tomato paste spoilage in factory process environments.

An Operator Perturbation Method of Polarized Line Transfer V ...

Indian Academy of Sciences (India)

tribpo

imate Lambda Iteration) method to the resonance scattering in spectral lines formed in the presence of weak magnetic fields. The method is based on an operator perturbation approach, and can efficiently give solutions for oriented vector magnetic fields in the solar atmosphere. Key words. ... 1999 for observational.

Kinetic Assembly of Near-IR Active Gold Nanoclusters using Weakly Adsorbing Polymers to Control Size

Science.gov (United States)

Tam, Jasmine M.; Murthy, Avinash K.; Ingram, Davis R.; Nguyen, Robin; Sokolov, Konstantin V.; Johnston, Keith P.

2013-01-01

Clusters of metal nanoparticles with an overall size less than 100 nm and high metal loadings for strong optical functionality, are of interest in various fields including microelectronics, sensors, optoelectronics and biomedical imaging and therapeutics. Herein we assemble ~5 nm gold particles into clusters with controlled size, as small as 30 nm and up to 100 nm, which contain only small amounts of polymeric stabilizers. The assembly is kinetically controlled with weakly adsorbing polymers, PLA(2K)-b-PEG(10K)-b-PLA(2K) or PEG (MW = 3350), by manipulating electrostatic, van der Waals (VDW), steric, and depletion forces. The cluster size and optical properties are tuned as a function of particle volume fractions and polymer/gold ratios to modulate the interparticle interactions. The close spacing between the constituent gold nanoparticles and high gold loadings (80–85% w/w gold) produce a strong absorbance cross section of ~9×10−15 m2 in the NIR at 700 nm. This morphology results from VDW and depletion attractive interactions that exclude the weakly adsorbed polymeric stabilizer from the cluster interior. The generality of this kinetic assembly platform is demonstrated for gold nanoparticles with a range of surface charges from highly negative to neutral, with the two different polymers. PMID:20361735

Application of industrial robots in automatic disassembly line of waste LCD displays

Science.gov (United States)

Wang, Sujuan

2017-11-01

In the automatic disassembly line of waste LCD displays, LCD displays are disassembled into plastic shells, metal shields, circuit boards, and LCD panels. Two industrial robots are used to cut metal shields and remove circuit boards in this automatic disassembly line. The functions of these two industrial robots, and the solutions to the critical issues of model selection, the interfaces with PLCs and the workflows were described in detail in this paper.

Outer measures and weak type estimates of Hardy-Littlewood maximal operators

Directory of Open Access Journals (Sweden)

Terasawa Yutaka

2006-01-01

Full Text Available We will introduce the times modified centered and uncentered Hardy-Littlewood maximal operators on nonhomogeneous spaces for . We will prove that the times modified centered Hardy-Littlewood maximal operator is weak type bounded with constant when if the Radon measure of the space has "continuity" in some sense. In the proof, we will use the outer measure associated with the Radon measure. We will also prove other results of Hardy-Littlewood maximal operators on homogeneous spaces and on the real line by using outer measures.

A weak balance: the contribution of muscle weakness to postural instability and falls.

NARCIS (Netherlands)

Horlings, G.C.; Engelen, B.G.M. van; Allum, J.H.J.; Bloem, B.R.

2008-01-01

Muscle strength is a potentially important factor contributing to postural control. In this article, we consider the influence of muscle weakness on postural instability and falling. We searched the literature for research evaluating muscle weakness as a risk factor for falls in community-dwelling

Trace metals in fluids lining the respiratory system of patients with idiopathic pulmonary fibrosis and diffuse lung diseases.

Science.gov (United States)

Bargagli, Elena; Lavorini, Federico; Pistolesi, Massimo; Rosi, Elisabetta; Prasse, Antje; Rota, Emilia; Voltolini, Luca

2017-07-01

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease with a poor prognosis and an undefined etiopathogenesis. Oxidative stress contributes to alveolar injury and fibrosis development and, because transition metals are essential to the functioning of most proteins involved in redox reactions, a better knowledge of metal concentrations and metabolism in the respiratory system of IPF patients may provide a valuable complementary approach to prevent and manage a disease which is often misdiagnosed or diagnosed in later stages. The present review summarizes and discusses literature data on the elemental composition of bronchoalveolar lavage (BAL), induced sputum and exhaled breath condensate (EBC) from patients affected by IPF and healthy subjects. Available data are scanty and the lack of consistent methods for the collection and analysis of lung and airways lining fluids makes it difficult to compare the results of different studies. However, the elemental composition of BAL samples from IPF patients seems to have a specific profile that can be distinguished from that of patients with other interstitial lung diseases (ILD) or control subjects. Suggestions are given towards standard sampling and analytical procedures of BAL samples, in the aim to assess typical element concentration patterns and their potential role as biomarkers of IPF. Copyright © 2017 Elsevier GmbH. All rights reserved.

Polarization of Coronal Forbidden Lines

Energy Technology Data Exchange (ETDEWEB)

Li, Hao; Qu, Zhongquan [Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan 650011 (China); Landi Degl’Innocenti, Egidio, E-mail: sayahoro@ynao.ac.cn [Dipartimento di Astronomia e Scienza dello Spazio, Università di Firenze, Largo E. Fermi 2, I-50125 Firenze (Italy)

2017-03-20

Since the magnetic field is responsible for most manifestations of solar activity, one of the most challenging problems in solar physics is the diagnostics of solar magnetic fields, particularly in the outer atmosphere. To this end, it is important to develop rigorous diagnostic tools to interpret polarimetric observations in suitable spectral lines. This paper is devoted to analyzing the diagnostic content of linear polarization imaging observations in coronal forbidden lines. Although this technique is restricted to off-limb observations, it represents a significant tool to diagnose the magnetic field structure in the solar corona, where the magnetic field is intrinsically weak and still poorly known. We adopt the quantum theory of polarized line formation developed in the framework of the density matrix formalism, and synthesize images of the emergent linear polarization signal in coronal forbidden lines using potential-field source-surface magnetic field models. The influence of electronic collisions, active regions, and Thomson scattering on the linear polarization of coronal forbidden lines is also examined. It is found that active regions and Thomson scattering are capable of conspicuously influencing the orientation of the linear polarization. These effects have to be carefully taken into account to increase the accuracy of the field diagnostics. We also found that linear polarization observation in suitable lines can give valuable information on the long-term evolution of the magnetic field in the solar corona.

X-ray K-edge analysis of drain lines in Wilhelm Hall, Ames Laboratory

International Nuclear Information System (INIS)

Jensen, T.; Whitmore, C.; Iowa State Univ., Ames, IA

1999-01-01

From August 12--27, 1998 X-ray K-edge measurements were made on drain lines in seven rooms in Wilhelm Hall, Ames Laboratory. The purpose of these measurements was to determine the extent of thorium (and other heavy metal) contamination inside these pipes. The K-edge method is a noninvasive inspection technique that can provide accurate quantification of heavy metal contamination interior to an object. Of the seven drain lines inspected, one was found to have no significant contamination, three showed significant thorium deposits, two showed mercury contamination, and one line was found to contain mercury, thorium and uranium. The K-edge measurements were found to be consistent with readings from hand-held survey meters, and provided much greater detail on the location and amount of heavy metal contamination

Elemental Abundances in the Broad Emission Line Region of Quasars at Redshifts larger than 4

DEFF Research Database (Denmark)

Dietrich, M.; Appenzeller, I.; Hamann, F.

2003-01-01

the chemical composition of the line emitting gas. Comparisons to photoionization calculations indicate gas metallicities in the broad emission line region in the range of solar to several times solar. The average of the mean metallicity of each high-z quasar in this sample is $Z/Z_\\odot = 4.3 \\pm 0...

Charged weak currents

International Nuclear Information System (INIS)

Turlay, R.

1979-01-01

In this review of charged weak currents I shall concentrate on inclusive high energy neutrino physics. There are surely still things to learn from the low energy weak interaction but I will not discuss it here. Furthermore B. Tallini will discuss the hadronic final state of neutrino interactions. Since the Tokyo conference a few experimental results have appeared on charged current interaction, I will present them and will also comment on important topics which have been published during the last past year. (orig.)

Weak-interacting holographic QCD

International Nuclear Information System (INIS)

Gazit, D.; Yee, H.-U.

2008-06-01

We propose a simple prescription for including low-energy weak-interactions into the frame- work of holographic QCD, based on the standard AdS/CFT dictionary of double-trace deformations. As our proposal enables us to calculate various electro-weak observables involving strongly coupled QCD, it opens a new perspective on phenomenological applications of holographic QCD. We illustrate efficiency and usefulness of our method by performing a few exemplar calculations; neutron beta decay, charged pion weak decay, and meson-nucleon parity non-conserving (PNC) couplings. The idea is general enough to be implemented in both Sakai-Sugimoto as well as Hard/Soft Wall models. (author)

Second class weak currents

International Nuclear Information System (INIS)

Delorme, J.

1978-01-01

The definition and general properties of weak second class currents are recalled and various detection possibilities briefly reviewed. It is shown that the existing data on nuclear beta decay can be consistently analysed in terms of a phenomenological model. Their implication on the fundamental structure of weak interactions is discussed [fr

Underwater electric field detection system based on weakly electric fish

Science.gov (United States)

Xue, Wei; Wang, Tianyu; Wang, Qi

2018-04-01

Weakly electric fish sense their surroundings in complete darkness by their active electric field detection system. However, due to the insufficient detection capacity of the electric field, the detection distance is not enough, and the detection accuracy is not high. In this paper, a method of underwater detection based on rotating current field theory is proposed to improve the performance of underwater electric field detection system. First of all, we built underwater detection system based on the theory of the spin current field mathematical model with the help of the results of previous researchers. Then we completed the principle prototype and finished the metal objects in the water environment detection experiments, laid the foundation for the further experiments.

THEORETICAL EVOLUTION OF OPTICAL STRONG LINES ACROSS COSMIC TIME

Energy Technology Data Exchange (ETDEWEB)

Kewley, Lisa J.; Dopita, Michael A.; Sutherland, Ralph [Research School for Astronomy and Astrophysics, Mount Stromlo Observatory, Cotter Road, Weston, ACT 2611 (Australia); Leitherer, Claus [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Dave, Romeel [Department of Astronomy/Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Yuan, Tiantian [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Allen, Mark [Observatoire de Strasbourg, UMR 7550, Strasbourg 67000 (France); Groves, Brent, E-mail: kewley@mso.anu.edu.au [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)

2013-09-10

We use the chemical evolution predictions of cosmological hydrodynamic simulations with our latest theoretical stellar population synthesis, photoionization, and shock models to predict the strong line evolution of ensembles of galaxies from z = 3 to the present day. In this paper, we focus on the brightest optical emission-line ratios, [N II]/H{alpha} and [O III]/H{beta}. We use the optical diagnostic Baldwin-Phillips-Terlevich (BPT) diagram as a tool for investigating the spectral properties of ensembles of active galaxies. We use four redshift windows chosen to exploit new near-infrared multi-object spectrographs. We predict how the BPT diagram will appear in these four redshift windows given different sets of assumptions. We show that the position of star-forming galaxies on the BPT diagram traces the interstellar medium conditions and radiation field in galaxies at a given redshift. Galaxies containing active galactic nucleus (AGN) form a mixing sequence with purely star-forming galaxies. This mixing sequence may change dramatically with cosmic time, due to the metallicity sensitivity of the optical emission-lines. Furthermore, the position of the mixing sequence may probe metallicity gradients in galaxies as a function of redshift, depending on the size of the AGN narrow-line region. We apply our latest slow shock models for gas shocked by galactic-scale winds. We show that at high redshift, galactic wind shocks are clearly separated from AGN in line ratio space. Instead, shocks from galactic winds mimic high metallicity starburst galaxies. We discuss our models in the context of future large near-infrared spectroscopic surveys.

Porous Metal Filters for Gas and Liquid Applications in the Nuclear Industry

International Nuclear Information System (INIS)

Kenneth, Rubow

2009-01-01

Sintered metal media are ideally suited for use in the most demanding industrial applications where long life is required and often other media are not cost-effective solution. As examples, filtration technology utilizing sintered metal media provides excellent performance in numerous liquid/solids and gas/solid separation applications found in the handling and processing of fluids containing radioactive materials. Many types of filter media, ranging from single use (disposable) to semi-permanent, are utilized today for separation of particulate matter. However, semi-permanent media are usually cleanable, either on or off-line, and are intended for sustainable, often multi-year, operating life in harsh environments. These harsh environments, which may involve corrosive fluids, high temperatures, high pressures or pressure spikes, often requiring continuous filtration service, are ideally suited for all-metal filtration systems employing semi-permanent sintered metal media. Sintered metal media, usually fabricated into tubular metal elements, have proven high particle removal efficiency and demonstrated reliability that uniquely afford excellent performance for demanding liquid/solids and gas/solids separation processes. The filter element and, in certain cases, the entire filter are weldable; therefore, the inherent sealing eliminates the need for potentially problematic seals. These media provide a positive barrier to ensure particulate removal to protect downstream equipment, for product separation, and/or to meet health, safety and environmental regulations. Typical applications for sintered metal media include: 1) gas and liquid filter systems used in various nuclear and radioactive waste processing applications, 2) an all-metal High Efficiency Particulate Air (HEPA) filter developed under Department of Energy (DOE) funding as an alternative to traditional HEPA filters fabricated with conventional glass fibers used on High Level Waste (HLW) tank ventilation

Standard and Null Weak Values

OpenAIRE

Zilberberg, Oded; Romito, Alessandro; Gefen, Yuval

2013-01-01

Weak value (WV) is a quantum mechanical measurement protocol, proposed by Aharonov, Albert, and Vaidman. It consists of a weak measurement, which is weighed in, conditional on the outcome of a later, strong measurement. Here we define another two-step measurement protocol, null weak value (NVW), and point out its advantages as compared to WV. We present two alternative derivations of NWVs and compare them to the corresponding derivations of WVs.

Observing broad-absorption line quasars with Spectrum-Rontgen-Gamma

DEFF Research Database (Denmark)

Singh, K.P.; Schnopper, H.W.; Westergaard, Niels Jørgen Stenfeldt

1998-01-01

Broad-absorption line quasars are found to have extremely weak soft X-ray emission when compared with other optically selected quasars. In the only example of PHL 5200 for which a detailed X-ray spectrum has been obtained with ASCA, strong absorption in the source appears to be responsible...

All-Metallic Vertical Transistors Based on Stacked Dirac Materials

OpenAIRE

Wang, Yangyang; Ni, Zeyuan; Liu, Qihang; Quhe, Ruge; Zheng, Jiaxin; Ye, Meng; Yu, Dapeng; Shi, Junjie; Yang, Jinbo; Lu, Jing

2014-01-01

It is an ongoing pursuit to use metal as a channel material in a field effect transistor. All metallic transistor can be fabricated from pristine semimetallic Dirac materials (such as graphene, silicene, and germanene), but the on/off current ratio is very low. In a vertical heterostructure composed by two Dirac materials, the Dirac cones of the two materials survive the weak interlayer van der Waals interaction based on density functional theory method, and electron transport from the Dirac ...

Sequential injection/bead injection lab-on-valve schemes for on-line solid phase extraction and preconcentration of ultra-trace levels of heavy metals with determination by ETAAS and ICPMS

DEFF Research Database (Denmark)

Wang, Jianhua; Hansen, Elo Harald; Miró, Manuel

2003-01-01

are focused on the applications of SI-BI-LOV protocols for on-line microcolumn based solid phase extraction of ultra-trace levels of heavy metals, employing the so-called renewable surface separation and preconcentration manipulatory scheme. Two types of sorbents have been employed as packing material...

Solubilization and localization of weakly polar lipids in unsonicated egg phosphatidylcholine: A 13C MAS NMR study

International Nuclear Information System (INIS)

Hamilton, J.A.; Fujito, D.T.; Hammer, C.F.

1991-01-01

The weakly polar lipids cholesteryl ester, triacylglycerol, and diacylglycerol incorporate to a limited extent into the lamellar structure of small unilamellar vesicles. The localization of the carbonyl group(s) at the aqueous interface was detected by [ 13 C]carbonyl chemical shift changes relative to the neat unhydrated lipid. This study uses 13 C NMR to investigate the interactions of thes lipids with unsonicated (multilamellar) phosphatidylcholine, a model system for cellular membranes and surfaces of emulsion particles with low curvature. Magic angle spinning reduced the broad lines of the unsonicated dispersions to narrow lines comparable to those from sonicated dispersions. [ 13 C]Carbonyl chemical shifts revealed incorporation of the three lipids into the lamellar structure of the unsonicated phospholipids and a partial hydration of the carbonyl groups similar to that observed in small vesicles. Other properties of interfacial weakly polar lipids in multilayers were similar to those in small unilamellar bilayers. There is thus a general tendency of weakly polar lipids to incorparate at least to a small extent into the lamellar structure of phospholipids and take on interfacial properties that are distinct from their bulk-phase properties. This pool of surface-located lipid is likely to be directly involved in enzymatyic transformations and protein-mediated transport. The 13 C magic angle spinning NMR method may be generally useful for determining the orientation of molecules in model membranes

Control of Chain Walking by Weak Neighbouring Group Interac-tions in Unsymmetric Catalysts

KAUST Repository

Falivene, Laura

2017-12-20

A combined theoretical and experimental study shows how weak attractive interactions of a neighbouring group can strongly promote chain walking and chain transfer. This accounts for the previously observed very different micro-structures obtained in ethylene polymerization by [κ^{2-N,O-{(2,6-(3\\',5\\'-R2C6H3)2C6H3-N=C(H)-(3,5-X,Y2-2-O-C6H2)}]NiCH3(pyridine)], namely hyperbranched oligomers for remote substituents R = CH3 versus. high molecular weight polyethylene for R = CF3. From a full mechanistic consideration the alkyl olefin complex with the growing chain cis to the salicylaldiminato oxygen donor is identified as the key species. Alternative to ethylene chain growth by insertion in this species, decoordination of the monomer to form a cis ß-agostic complex provides an entry into branching and chain transfer pathways. This release of monomer is promoted and made competitive by a weak η2-coordination of the distal aryl rings to the metal center, operative only for the case of sufficiently electron rich aryls. This concept for controlling chain walking is underlined by catalysts with other weakly coordinating furane and thio-phene motifs, which afford highly branched oligomers with > 120 branches per 1000 carbon atoms.}

The Metallicity Evolution of Blue Compact Dwarf Galaxies from the Intermediate Redshift to the Local Universe

Science.gov (United States)

Lian, Jianhui; Hu, Ning; Fang, Guanwen; Ye, Chengyun; Kong, Xu

2016-03-01

We present oxygen abundance measurements for 74 blue compact dwarf (BCD) galaxies in the redshift range of [0.2, 0.5] using the strong-line method. The spectra of these objects are taken using Hectospec on the Multiple Mirror Telescope. More than half of these BCDs had dust attenuation corrected using the Balmer decrement method. For comparison, we also selected a sample of 2023 local BCDs from the Sloan Digital Sky Survey (SDSS) database. Based on the local and intermediate-z BCD samples, we investigated the cosmic evolution of the metallicity, star formation rate (SFR), and Dn(4000) index. Compared with local BCDs, the intermediate-z BCDs had a systematically higher R23 ratio but a similar O32 ratio. Interestingly, no significant deviation in the mass-metallicity (MZ) relation was found between the intermediate-z and local BCDs. Besides the metallicity, the intermediate-z BCDs also exhibited an SFR distribution that was consistent with local BCDs, suggesting a weak dependence on redshift. The intermediate-z BCDs seemed to be younger than the local BCDs with lower Dn(4000) index values. The insignificant deviation in the mass-metallicity and mass-SFR relations between intermediate-z and local BCDs indicates that the relations between the global parameters of low-mass compact galaxies may be universal. These results from low-mass compact galaxies could be used to place important observational constraints on galaxy formation and evolution models.

THE METALLICITY EVOLUTION OF BLUE COMPACT DWARF GALAXIES FROM THE INTERMEDIATE REDSHIFT TO THE LOCAL UNIVERSE

International Nuclear Information System (INIS)

Lian, Jianhui; Hu, Ning; Ye, Chengyun; Kong, Xu; Fang, Guanwen

2016-01-01

We present oxygen abundance measurements for 74 blue compact dwarf (BCD) galaxies in the redshift range of [0.2, 0.5] using the strong-line method. The spectra of these objects are taken using Hectospec on the Multiple Mirror Telescope. More than half of these BCDs had dust attenuation corrected using the Balmer decrement method. For comparison, we also selected a sample of 2023 local BCDs from the Sloan Digital Sky Survey (SDSS) database. Based on the local and intermediate-z BCD samples, we investigated the cosmic evolution of the metallicity, star formation rate (SFR), and D n (4000) index. Compared with local BCDs, the intermediate-z BCDs had a systematically higher R23 ratio but a similar O32 ratio. Interestingly, no significant deviation in the mass–metallicity (MZ) relation was found between the intermediate-z and local BCDs. Besides the metallicity, the intermediate-z BCDs also exhibited an SFR distribution that was consistent with local BCDs, suggesting a weak dependence on redshift. The intermediate-z BCDs seemed to be younger than the local BCDs with lower D n (4000) index values. The insignificant deviation in the mass–metallicity and mass–SFR relations between intermediate-z and local BCDs indicates that the relations between the global parameters of low-mass compact galaxies may be universal. These results from low-mass compact galaxies could be used to place important observational constraints on galaxy formation and evolution models

THE METALLICITY EVOLUTION OF BLUE COMPACT DWARF GALAXIES FROM THE INTERMEDIATE REDSHIFT TO THE LOCAL UNIVERSE

Energy Technology Data Exchange (ETDEWEB)

Lian, Jianhui; Hu, Ning; Ye, Chengyun; Kong, Xu [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026 (China); Fang, Guanwen, E-mail: ljhhw@mail.ustc.edu.cn, E-mail: xkong@ustc.edu.cn [Institute for Astronomy and History of Science and Technology, Dali University, Dali 671003 (China)

2016-03-01

We present oxygen abundance measurements for 74 blue compact dwarf (BCD) galaxies in the redshift range of [0.2, 0.5] using the strong-line method. The spectra of these objects are taken using Hectospec on the Multiple Mirror Telescope. More than half of these BCDs had dust attenuation corrected using the Balmer decrement method. For comparison, we also selected a sample of 2023 local BCDs from the Sloan Digital Sky Survey (SDSS) database. Based on the local and intermediate-z BCD samples, we investigated the cosmic evolution of the metallicity, star formation rate (SFR), and D{sub n}(4000) index. Compared with local BCDs, the intermediate-z BCDs had a systematically higher R23 ratio but a similar O32 ratio. Interestingly, no significant deviation in the mass–metallicity (MZ) relation was found between the intermediate-z and local BCDs. Besides the metallicity, the intermediate-z BCDs also exhibited an SFR distribution that was consistent with local BCDs, suggesting a weak dependence on redshift. The intermediate-z BCDs seemed to be younger than the local BCDs with lower D{sub n}(4000) index values. The insignificant deviation in the mass–metallicity and mass–SFR relations between intermediate-z and local BCDs indicates that the relations between the global parameters of low-mass compact galaxies may be universal. These results from low-mass compact galaxies could be used to place important observational constraints on galaxy formation and evolution models.

Flux-line-cutting losses in type-II superconductors

International Nuclear Information System (INIS)

Clem, J.R.

1982-01-01

Energy dissipation associated with flux-line cutting (intersection and cross-joining of adjacent nonparallel vortices) is considered theoretically. The flux-line-cutting contribution to the dissipation per unit volume, arising from mutual annihilation of transverse magnetic flux, is identified as J/sub parallel/xE/sub parallel/, where J/sub parallel/ and E/sub parallel/ are the components of the current density and the electric field parallel to the magnetic induction. The dynamical behavior of the magnetic structure at the flux-line-cutting threshold is shown to be governed by a special critical-state model similar to that proposed by previous authors. The resulting flux-line-cutting critical-state model, characterized in planar geometry by a parallel critical current density J/sub c/parallel or a critical angle gradient k/sub c/, is used to calculate predicted hysteretic ac flux-line-cutting losses in type-II superconductors in which the flux pinning is weak. The relation of the theory to previous experiments is discussed

Chemodynamics of heavy metals in long-term contaminated soils: metal speciation in soil solution.

Science.gov (United States)

Kim, Kwon-Rae; Owens, Gary

2009-01-01

The concentration and speciation of heavy metals in soil solution isolated from long-term contaminated soils were investigated. The soil solution was extracted at 70% maximum water holding capacity (MWHC) after equilibration for 24 h. The free metal concentrations (Cd2+, CU2+, Pb2+, and Zn2+) in soil solution were determined using the Donnan membrane technique (DMT). Initially the DMT was validated using artificial solutions where the percentage of free metal ions were significantly correlated with the percentages predicted using MINTEQA2. However, there was a significant difference between the absolute free ion concentrations predicted by MINTEQA2 and the values determined by the DMT. This was due to the significant metal adsorption onto the cation exchange membrane used in the DMT with 20%, 28%, 44%, and 8% mass loss of the initial total concentration of Cd, Cu, Pb, and Zn in solution, respectively. This could result in a significant error in the determination of free metal ions when using DMT if no allowance for membrane cation adsorption was made. Relative to the total soluble metal concentrations the amounts of free Cd2+ (3%-52%) and Zn2+ (11%-72%) in soil solutions were generally higher than those of Cu2+ (0.2%-30%) and Pb2+ (0.6%-10%). Among the key soil solution properties, dissolved heavy metal concentrations were the most significant factor governing free metal ion concentrations. Soil solution pH showed only a weak relationship with free metal ion partitioning coefficients (K(p)) and dissolved organic carbon did not show any significant influence on K(p).

Weak interactions

International Nuclear Information System (INIS)

Chanda, R.

1981-01-01

The theoretical and experimental evidences to form a basis for Lagrangian Quantum field theory for Weak Interactions are discussed. In this context, gauge invariance aspects of such interactions are showed. (L.C.) [pt

MHTGR steam generator on-line heat balance, instrumentation and function

International Nuclear Information System (INIS)

Klapka, R.E.; Howard, W.W.; Etzel, K.T.; Basol, M.; Karim, N.U.

1991-09-01

Instrumentation is used to measure the Modular High Temperature Gas-Cooled Reactor (MHTGR) steam generator dissimilar metal weld temperature during start-up testing. Additional instrumentation is used to determine an on-line heat balance which is maintained during the 40 year module life. In the process of calibrating the on-line heat balance, the helium flow is adjusted to yield the optimum boiling level in the steam generator relative to the dissimilar metal weld. After calibration is complete the weld temperature measurement is non longer required. The reduced boiling level range results in less restrictive steam generator design constraints

Cosmology with weak lensing surveys

International Nuclear Information System (INIS)

Munshi, Dipak; Valageas, Patrick; Waerbeke, Ludovic van; Heavens, Alan

2008-01-01

Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening matter. The distortions are due to fluctuations in the gravitational potential, and are directly related to the distribution of matter and to the geometry and dynamics of the Universe. As a consequence, weak gravitational lensing offers unique possibilities for probing the Dark Matter and Dark Energy in the Universe. In this review, we summarise the theoretical and observational state of the subject, focussing on the statistical aspects of weak lensing, and consider the prospects for weak lensing surveys in the future. Weak gravitational lensing surveys are complementary to both galaxy surveys and cosmic microwave background (CMB) observations as they probe the unbiased non-linear matter power spectrum at modest redshifts. Most of the cosmological parameters are accurately estimated from CMB and large-scale galaxy surveys, so the focus of attention is shifting to understanding the nature of Dark Matter and Dark Energy. On the theoretical side, recent advances in the use of 3D information of the sources from photometric redshifts promise greater statistical power, and these are further enhanced by the use of statistics beyond two-point quantities such as the power spectrum. The use of 3D information also alleviates difficulties arising from physical effects such as the intrinsic alignment of galaxies, which can mimic weak lensing to some extent. On the observational side, in the next few years weak lensing surveys such as CFHTLS, VST-KIDS and Pan-STARRS, and the planned Dark Energy Survey, will provide the first weak lensing surveys covering very large sky areas and depth. In the long run even more ambitious programmes such as DUNE, the Supernova Anisotropy Probe (SNAP) and Large-aperture Synoptic Survey Telescope (LSST) are planned. Weak lensing of diffuse components such as the CMB and 21 cm emission can also

Cosmology with weak lensing surveys

Energy Technology Data Exchange (ETDEWEB)

Munshi, Dipak [Institute of Astronomy, Madingley Road, Cambridge, CB3 OHA (United Kingdom); Astrophysics Group, Cavendish Laboratory, Madingley Road, Cambridge CB3 OHE (United Kingdom)], E-mail: munshi@ast.cam.ac.uk; Valageas, Patrick [Service de Physique Theorique, CEA Saclay, 91191 Gif-sur-Yvette (France); Waerbeke, Ludovic van [University of British Columbia, Department of Physics and Astronomy, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Heavens, Alan [SUPA - Scottish Universities Physics Alliance, Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)

2008-06-15

Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening matter. The distortions are due to fluctuations in the gravitational potential, and are directly related to the distribution of matter and to the geometry and dynamics of the Universe. As a consequence, weak gravitational lensing offers unique possibilities for probing the Dark Matter and Dark Energy in the Universe. In this review, we summarise the theoretical and observational state of the subject, focussing on the statistical aspects of weak lensing, and consider the prospects for weak lensing surveys in the future. Weak gravitational lensing surveys are complementary to both galaxy surveys and cosmic microwave background (CMB) observations as they probe the unbiased non-linear matter power spectrum at modest redshifts. Most of the cosmological parameters are accurately estimated from CMB and large-scale galaxy surveys, so the focus of attention is shifting to understanding the nature of Dark Matter and Dark Energy. On the theoretical side, recent advances in the use of 3D information of the sources from photometric redshifts promise greater statistical power, and these are further enhanced by the use of statistics beyond two-point quantities such as the power spectrum. The use of 3D information also alleviates difficulties arising from physical effects such as the intrinsic alignment of galaxies, which can mimic weak lensing to some extent. On the observational side, in the next few years weak lensing surveys such as CFHTLS, VST-KIDS and Pan-STARRS, and the planned Dark Energy Survey, will provide the first weak lensing surveys covering very large sky areas and depth. In the long run even more ambitious programmes such as DUNE, the Supernova Anisotropy Probe (SNAP) and Large-aperture Synoptic Survey Telescope (LSST) are planned. Weak lensing of diffuse components such as the CMB and 21 cm emission can also

Quantum degeneracy corrections to plasma line emission and to Saha equation

International Nuclear Information System (INIS)

Molinari, V.G.; Mostacci, D.; Rocchi, F.; Sumini, M.

2003-01-01

The effect of quantum degeneracy on the electron collisional excitation is investigated, and its effects on line emission evaluated for applications to spectroscopy of dense, cold plasmas. A correction to Saha equation for weakly-degenerate plasmas is also presented

Analysis of trace inorganic anions in weak acid salts by single pump cycling-column-switching ion chromatography.

Science.gov (United States)

Huang, Zhongping; Ni, Chengzhu; Zhu, Zhuyi; Pan, Zaifa; Wang, Lili; Zhu, Yan

2015-05-01

The application of ion chromatography with the single pump cycling-column-switching technique was described for the analysis of trace inorganic anions in weak acid salts within a single run. Due to the hydrogen ions provided by an anion suppressor electrolyzing water, weak acid anions could be transformed into weak acids, existing as molecules, after passing through the suppressor. Therefore, an anion suppressor and ion-exclusion column were adopted to achieve on-line matrix elimination of weak acid anions with high concentration for the analysis of trace inorganic anions in weak acid salts. A series of standard solutions consisting of target anions of various concentrations from 0.005 to 10 mg/L were analyzed, with correlation coefficients r ≥ 0.9990. The limits of detection were in the range of 0.67 to 1.51 μg/L, based on the signal-to-noise ratio of 3 and a 25 μL injection volume. Relative standard deviations for retention time, peak area, and peak height were all less than 2.01%. A spiking study was performed with satisfactory recoveries between 90.3 and 104.4% for all anions. The chromatographic system was successfully applied to the analysis of trace inorganic anions in five weak acid salts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hyperfine field distribution of Fe83B17 glassy metal

International Nuclear Information System (INIS)

Miglierini, M.; Sitek, J.

1990-01-01

Convolutions of Gaussian and Lorentzian lines are proposed to fit the Moessbauer spectrum of Fe 83 B 17 metallic glass. The hyperfine field distribution is constructed from three Gaussian lines corresponding to the individual line pairs. (author). 1 fig., 7 refs

Reliable Line Matching Algorithm for Stereo Images with Topological Relationship

Directory of Open Access Journals (Sweden)

WANG Jingxue

2017-11-01

Full Text Available Because of the lack of relationships between matching line and adjacent lines in the process of individual line matching, and the weak reliability of the individual line descriptor facing on discontinue texture, this paper presents a reliable line matching algorithm for stereo images with topological relationship. The algorithm firstly generates grouped line pairs from lines extracted from the reference image and searching image according to the basic topological relationships such as distance and angle between the lines. Then it takes the grouped line pairs as matching primitives, and matches these grouped line pairs by using epipolar constraint, homography constraint, quadrant constraint and gray correlation constraint of irregular triangle in order. And finally, it resolves the corresponding line pairs into two pairs of corresponding individual lines, and obtains one to one matching results after the post-processing of integrating, fitting, and checking. This paper adopts digital aerial images and close-range images with typical texture features to deal with the parameter analysis and line matching, and the experiment results demonstrate that the proposed algorithm in this paper can obtain reliable line matching results.

Effects of excitation spectral width on decay profile of weakly confined excitons

International Nuclear Information System (INIS)

Kojima, O.; Isu, T.; Ishi-Hayase, J.; Kanno, A.; Katouf, R.; Sasaki, M.; Tsuchiya, M.

2008-01-01

We report the effect due to a simultaneous excitation of several exciton states on the radiative decay profiles on the basis of the nonlocal response of weakly confined excitons in GaAs thin films. In the case of excitation of single exciton state, the transient grating signal has two decay components. The fast decay component comes from nonlocal response, and the long-lived component is attributed to free exciton decay. With an increase of excitation spectral width, the nonlocal component becomes small in comparison with the long-lived component, and disappears under irradiation of a femtosecond-pulse laser with broader spectral width. The transient grating spectra clearly indicates the contribution of the weakly confined excitons to the signal, and the exciton line width hardly changes by excitation spectral width. From these results, we concluded that the change of decay profile is attributed not to the many-body effect but to the effect of simultaneous excitation of several exciton states

Transport measurements on superconducting YBa2Cu3O7-δ thin film lines

International Nuclear Information System (INIS)

Moeckly, B.H.; Lathrop, D.K.; Redinbo, G.F.; Russek, S.E.; Buhrman, R.A.

1990-01-01

Critical current densities, magnetic field response, and microwave response have been measured for laser ablated YBa 2 Cu 3 O 7-δ thin film lines on MgO and SrTiO 3 substrates. Films on SrTiO 3 have critical current densities > 1 x 10 6 A/cm 2 at 77 K and show uniform transport properties in lines of all sizes. Films on MgO have critical current densities which range between 10 2 and 10 6 A/cm 2 at 77 K and show considerable variation from device to device on the same chip. Narrow lines on MgO with low critical current densities show Josephson weak link structure which includes RSJ-like IV curves, microwave induced constant voltage steps, and a high sensitivity to magnetic field. The presence of the Josephson weak links if correlated with small amounts of misaligned grains in film on MgO

Antiproliferative activity of flavonoids on several cancer cell lines.

Science.gov (United States)

Kawaii, S; Tomono, Y; Katase, E; Ogawa, K; Yano, M

1999-05-01

Twenty-seven Citrus flavonoids were examined for their antiproliferative activities against several tumor and normal human cell lines. As a result, 7 flavonoids were judged to be active against the tumor cell lines, while they had weak antiproliferative activity against the normal human cell lines. The rank order of potency was luteolin, natsudaidain, quercetin, tangeretin, eriodictyol, nobiletin, and 3,3',4',5,6,7,8-heptamethoxyflavone. The structure-activity relationship established from comparison among these flavones and flavanones showed that the ortho-catechol moiety in ring B and a C2-C3 double bond were important for the antiproliferative activity. As to polymethoxylated flavones, C-3 hydroxyl and C-8 methoxyl groups were essential for high activity.

Hydrogen Mobility in Disordered Metals Studied by $\\mu$SR

CERN Multimedia

2002-01-01

A few studies of the behaviour of positive muons in metal hydrides have been made during the last three years under the code SC76, although this code is intended primarily for ``diffusion and trapping of positive muons`` in pure or very weakly doped metals. It has been shown in these studies that $\\mu$SR can provide important information even in concentrated hydrides like $ NbH _{,} _{0},7 - _{0} _{,} _{9} $ and $ Zr V _{2} H _{2} _{m}inus _{3} $ especially concerning mutual $\\mu

Pressure dependence of the magnetic properties of various weakly ferromagnetic transition metal alloys

International Nuclear Information System (INIS)

Buis, N.

1979-01-01

A large number of experimental results are summarized obtained in an apparatus designed for the measurement of magnetization under high pressures (up to 5k bar gas pressure), at temperatures from 4.2K to room temperature and in magnetic fields up to 5.1 T. Two alloy systems studied were Zr (Fesub(1-x)Cosub(x)) 2 and Y(Fesub(x)Cosub(1-x)) 2 and no consistent picture could be deduced from the large pressure effects on the magnetization. Apparently, one cannot apply the model for weak itinerant ferromagnetism on Zr(Fesub(1-x)Cosub(x)) 2 or a simple giant moment model on Y(Fesub(x)Cosub(1-x)) 2 with small iron content, because the magnetic behaviour of both systems is too complicated. (C.F.)

First light - II. Emission line extinction, population III stars, and X-ray binaries

Science.gov (United States)

Barrow, Kirk S. S.; Wise, John H.; Aykutalp, Aycin; O'Shea, Brian W.; Norman, Michael L.; Xu, Hao

2018-02-01

We produce synthetic spectra and observations for metal-free stellar populations and high-mass X-ray binaries in the Renaissance Simulations at a redshift of 15. We extend our methodology from the first paper in the series by modelling the production and extinction of emission lines throughout a dusty and metal-enriched interstellar and circum-galactic media extracted from the simulation, using a Monte Carlo calculation. To capture the impact of high-energy photons, we include all frequencies from hard X-ray to far-infrared with enough frequency resolution to discern line emission and absorption profiles. The most common lines in our sample in order of their rate of occurrence are Ly α, the C IV λλ1548, 1551 doublet, H α, and the Ca II λλλ8498, 8542, 8662 triplet. The best scenario for a direct observation of a metal-free stellar population is a merger between two Population III Galaxies. In mergers between metal-enriched and metal-free stellar populations, some characteristics may be inferred indirectly. Single Population III galaxies are too dim to be observed photometrically at z = 15. Ly α emission is discernible by JWST as an increase in J200w - J277w colour off the intrinsic stellar tracks. Observations of metal-free stars will be difficult, though not impossible, with the next generation of space telescopes.

Extremely weak magnetic field exposure may inhibit hippocampal neurogenesis of Sprague Dawley rats

Science.gov (United States)

Zhang, B.; Tian, L.; Cai, Y.; Xu, H.; Pan, Y.

2016-12-01

Hippocampal neurogenesis occurs throughout life in mammals brains and can be influenced by animals' age as well as environmental factors. Lines of evidences have shown that the magnetic field is an important physics environmental factor influencing many animals' growth and development, and extremely weak magnetic field exposures have been proved having serious adverse effects on the metabolism and behaviors in some animals, but few studies have examined the response of hippocampal neurogenesis to it. In the present study, we experimentally examined the extremely weak magnetic field effects on neurogenesis of the dentate gyrus (DG) of hippocampus of adult Sprague Dawley (SD) rats. Two types of magnetic fields were used, an extremely weak magnetic field (≤ 0.5μT) and the geomagnetic fields (strength 31-58μT) as controls. Thirty-two SD rats (3-weeks old) were used in this study. New cell survival in hippocampus was assessed at 0, 14, 28, and 42 days after a 7-day intraperitoneal injections of 5-bromo-2'-deoxyuridine (BrdU). Meanwhile, the amounts of immature neurons and mature neurons which are both related to hippocampal neurogenesis, as documented by labeling with doublecortin (DCX) and neuron (NeuN), respectively, were also analyzed at 0, 14, 28, and 42 days. Compared with geomagnetic field exposure groups, numbers of BrdU-, DCX-positive cells of DG of hippocampus in tested rats reduces monotonously and more rapidly after 14 days, and NeuN-positive cells significantly decreases after 28days when exposed in the extremely weak magnetic field condition. Our data suggest that the exposure to an extremely weak magnetic field may suppress the neurogenesis in DG of SD rats.

Feasibility of isotachochromatography as a method for the preparative separation of weak acids and weak bases. I. Theoretical considerations

NARCIS (Netherlands)

Kooistra, C.; Sluyterman, L.A.A.E.

1988-01-01

The fundamental equation of isotachochromatography, i.e., isotachophoresis translated into ion-exchange chromatography, has been derived for weak acids and weak bases. Weak acids are separated on strong cation exchangers and weak bases on strong anion exchangers. According to theory, the elution

Detection of heavy metal Cd in polluted fresh leafy vegetables by laser-induced breakdown spectroscopy.

Science.gov (United States)

Yao, Mingyin; Yang, Hui; Huang, Lin; Chen, Tianbing; Rao, Gangfu; Liu, Muhua

2017-05-10

In seeking a novel method with the ability of green analysis in monitoring toxic heavy metals residue in fresh leafy vegetables, laser-induced breakdown spectroscopy (LIBS) was applied to prove its capability in performing this work. The spectra of fresh vegetable samples polluted in the lab were collected by optimized LIBS experimental setup, and the reference concentrations of cadmium (Cd) from samples were obtained by conventional atomic absorption spectroscopy after wet digestion. The direct calibration employing intensity of single Cd line and Cd concentration exposed the weakness of this calibration method. Furthermore, the accuracy of linear calibration can be improved a little by triple Cd lines as characteristic variables, especially after the spectra were pretreated. However, it is not enough in predicting Cd in samples. Therefore, partial least-squares regression (PLSR) was utilized to enhance the robustness of quantitative analysis. The results of the PLSR model showed that the prediction accuracy of the Cd target can meet the requirement of determination in food safety. This investigation presented that LIBS is a promising and emerging method in analyzing toxic compositions in agricultural products, especially combined with suitable chemometrics.

Antiproliferative effect of isopentenylated coumarins on several cancer cell lines.

Science.gov (United States)

Kawaii, S; Tomono, Y; Ogawa, K; Sugiura, M; Yano, M; Yoshizawa, Y; Ito, C; Furukawa, H

2001-01-01

33 coumarins, mainly the simple isopentenylated coumarins and derived pyrano- and furanocoumarins, were examined for their antiproliferative activity towards several cancer and normal human cell lines. The pyrano- and furanocoumarins showed strong activity against the cancer cell lines, whereas they had weak antiproliferative activity against the normal human cell lines. The decreasing rank order of potency was osthenone (10), clausarin (25), clausenidin (26), dentatin (24), nordentatin (23), imperatorin (29), seselin (27), xanthyletin (21), suberosin (17), phebalosin (8) and osthol (12). The structure-activity relationship established from the results revealed that the 1,1-dimethylallyl and isopentenyl groups have an important role for antiproliferative activity.

Spectro web: oscillator strength measurements of atomic absorption lines in the sun and procyon

International Nuclear Information System (INIS)

Lobel, A

2008-01-01

We update the online SpectroWeb database of spectral standard reference stars with 1178 oscillator strength values of atomic absorption lines observed in the optical spectrum of the Sun and Procyon (α CMi A). The updated line oscillator strengths are measured with best fits to the disk-integrated KPNO-FTS spectrum of the Sun observed between 4000 A and 6800 A using state-of-the-art detailed spectral synthesis calculations. A subset of 660 line oscillator strengths is validated with synthetic spectrum calculations of Procyon observed with ESO-UVES between 4700 A and 6800 A. The new log(gf)-values in SpectroWeb are improvements upon the values offered in the online Vienna Atomic Line Database (VALD). We find for neutral iron-group elements, such as Fe I, Ni I, Cr I, and Ti I, a statistically significant over-estimation of the VALD log((gf)-values for weak absorption lines with normalized central line depths below 15 %. For abundant lighter elements (e.g. Mg I and Ca I) this trend is statistically not significantly detectable, with the exception of Si I for which the log(gf)-values of 60 weak and medium-strong lines are substantially decreased to best fit the observed spectra. The newly measured log(gf)-values are available in the SpectroWeb database at http://spectra.freeshell.org, which interactively displays the observed and computed stellar spectra, together with corresponding atomic line data.

Fabrication of subwavelength metallic structures by using a metal direct imprinting process

International Nuclear Information System (INIS)

Hsieh, C W; Hsiung, H Y; Lu, Y T; Sung, C K; Wang, W H

2007-01-01

This work employs a metal direct imprinting process, which possesses the characteristics of simplicity, low-cost and high resolution, for the fabrication of subwavelength structures on a metallic thin film. Herein, the mould featuring periodic line structures is manufactured by using E-beam lithography and followed by a dry etching process; meanwhile, the thin film is fabricated by sputtering Al on a silicon substrate. AFM section analyses are employed to measure imprinting depths of the subwavelength metallic structures and it is found that the uniformity of the imprinting depths is affected by the designed patterns, the material property of thin film and mould deformation. The process temperature and the mould filling that influence the transferred quality are investigated. In addition, TEM is also utilized to examine defects in the subwavelength metallic structures. Finally, good quality subwavelength metallic structures are fabricated under a pressure of 300 MPa for 60 s at room temperature. In this study, we have demonstrated that subwavelength metallic structures with a minimum linewidth of less than 100 nm on the Al thin film are successfully constructed by the metal direct imprinting process

The antiproliferative effect of acridone alkaloids on several cancer cell lines.

Science.gov (United States)

Kawaii, S; Tomono, Y; Katase, E; Ogawa, K; Yano, M; Takemura, Y; Ju-ichi, M; Ito, C; Furukawa, H

1999-04-01

Fifteen acridone alkaloids were examined for their antiproliferative activity toward monolayers and suspension of several types of cancer and normal human cell lines. As a result, atalaphyllidine (9), 5-hydroxy-N-methylseverifoline (11), atalaphyllinine (12), and des-N-methylnoracronycine (13) showed potent antiproliferative activity against tumor cell lines, whereas they have weak cytotoxicity on normal human cell lines. The structure-activity relationship established from the results revealed that a secondary amine, hydroxyl groups at C-1 and C-5, and a prenyl group at C-2 played an important role for antiproliferative activities of the tetracyclic acridones.

A joint time-invariant wavelet transform and kurtosis approach to the improvement of in-line oil debris sensor capability

International Nuclear Information System (INIS)

Fan, X; Liang, M; Yeap, T

2009-01-01

In-line oil debris sensors are important devices for the detection of machinery failures. However, two key issues remain to be addressed to more effectively make use of the existing oil debris sensors: the responsiveness to early machine failures and false alarms. The responsiveness level depends on the size of the debris that can be detected by an oil debris sensor. The detectable particle size in turn is mainly limited by the background noise. The false alarms are often caused by spurious impulses such as vibration-like signals. The challenge of improving the responsiveness and reducing false alarms lies in the very weak particle signals and their similarity to spurious signals. In this paper, a joint time-invariant wavelet transform and kurtosis analysis method is proposed to address the two issues simultaneously. The proposed method has been tested by extracting signatures of ultra-small metal particles from background noise and a wide range of simulated vibration-like and real vibration signals. Our test results have demonstrated that the proposed method can effectively detect very weak particle signals buried in strong background noise and eliminate vibration-like spurious signals. The implementation of the proposed method will substantially enhance many existing oil debris sensors

Large N lattice QCD and its extended strong-weak connection to the hypersphere

International Nuclear Information System (INIS)

Christensen, Alexander S.; Myers, Joyce C.; Pedersen, Peter D.

2014-01-01

We calculate an effective Polyakov line action of QCD at large N c and large N f from a combined lattice strong coupling and hopping expansion working to second order in both, where the order is defined by the number of windings in the Polyakov line. We compare with the action, truncated at the same order, of continuum QCD on S 1 ×S d at weak coupling from one loop perturbation theory, and find that a large N c correspondence of equations of motion found in http://dx.doi.org/10.1007/JHEP10(2012)067 at leading order, can be extended to the next order. Throughout the paper, we review the background necessary for computing higher order corrections to the lattice effective action, in order to make higher order comparisons more straightforward

Phase coherence and Rabi frequency induced ultranarrow spectral line

International Nuclear Information System (INIS)

Dutta, Bibhas Kumar; Panchadhyayee, Pradipta; Mahapatra, Prasanta Kumar

2012-01-01

A scheme is proposed to achieve ultranarrow spectral line in the fluorescence spectrum of a lifetime broadened multilevel phase-coherent atom. It is shown that for weak-field coupling, ultranarrow spectral feature in the fluorescence spectrum can be generated by controlling the values of the Rabi frequencies involved in the coherent mechanism of the system. For fixed values of the Rabi frequencies in the weak-field limit, ultranarrow feature appears in the spectrum through the adjustment of the relative phase of the coherent fields. The results highlight that, larger the values of the decay rates associated with the field-driven channels, more pronounced is the phenomenon of narrowing in the spectrum.

Riemann Geometric Color-Weak Compensationfor Individual Observers

OpenAIRE

Kojima, Takanori; Mochizuki, Rika; Lenz, Reiner; Chao, Jinhui

2014-01-01

We extend a method for color weak compensation based on the criterion of preservation of subjective color differences between color normal and color weak observers presented in [2]. We introduce a new algorithm for color weak compensation using local affine maps between color spaces of color normal and color weak observers. We show howto estimate the local affine map and how to determine correspondences between the origins of local coordinates in color spaces of color normal and color weak ob...

ALMA WILL DETERMINE THE SPECTROSCOPIC REDSHIFT z > 8 WITH FIR [O III] EMISSION LINES

Energy Technology Data Exchange (ETDEWEB)

Inoue, A. K.; Shimizu, I. [College of General Education, Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530 (Japan); Tamura, Y. [Institute of Astronomy, The University of Tokyo, Mitaka, Tokyo 181-0015 (Japan); Matsuo, H. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Okamoto, T. [Department of Cosmosciences, Graduate School of Science, Hokkaido University, N10 W8, Kitaku, Sapporo 060-0810 (Japan); Yoshida, N., E-mail: akinoue@las.osaka-sandai.ac.jp [Department of Physics, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033 (Japan)

2014-01-10

We investigate the potential use of nebular emission lines in the rest-frame far-infrared (FIR) for determining spectroscopic redshift of z > 8 galaxies with the Atacama Large Millimeter/submillimeter Array (ALMA). After making a line emissivity model as a function of metallicity, especially for the [O III] 88 μm line which is likely to be the strongest FIR line from H II regions, we predict the line fluxes from high-z galaxies based on a cosmological hydrodynamics simulation of galaxy formation. Since the metallicity of galaxies reaches at ∼0.2 Z {sub ☉} even at z > 8 in our simulation, we expect the [O III] 88 μm line as strong as 1.3 mJy for 27 AB objects, which is detectable at a high significance by <1 hr integration with ALMA. Therefore, the [O III] 88 μm line would be the best tool to confirm the spectroscopic redshifts beyond z = 8.

BUOYANCY INSTABILITIES IN A WEAKLY COLLISIONAL INTRACLUSTER MEDIUM

Energy Technology Data Exchange (ETDEWEB)

Kunz, Matthew W.; Stone, James M. [Department of Astrophysical Sciences, Princeton University, Peyton Hall, 4 Ivy Lane, Princeton, NJ 08544 (United States); Bogdanovic, Tamara; Reynolds, Christopher S., E-mail: kunz@astro.princeton.edu, E-mail: jstone@astro.princeton.edu, E-mail: tamarab@astro.umd.edu, E-mail: chris@astro.umd.edu [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

2012-08-01

The intracluster medium (ICM) of galaxy clusters is a weakly collisional plasma in which the transport of heat and momentum occurs primarily along magnetic-field lines. Anisotropic heat conduction allows convective instabilities to be driven by temperature gradients of either sign: the magnetothermal instability (MTI) in the outskirts of clusters and the heat-flux buoyancy-driven instability (HBI) in their cooling cores. We employ the Athena magnetohydrodynamic code to investigate the nonlinear evolution of these instabilities, self-consistently including the effects of anisotropic viscosity (i.e., Braginskii pressure anisotropy), anisotropic conduction, and radiative cooling. We find that, in all but the innermost regions of cool-core clusters, anisotropic viscosity significantly impairs the ability of the HBI to reorient magnetic-field lines orthogonal to the temperature gradient. Thus, while radio-mode feedback appears necessary in the central few Multiplication-Sign 10 kpc, heat conduction may be capable of offsetting radiative losses throughout most of a cool core over a significant fraction of the Hubble time. Magnetically aligned cold filaments are then able to form by local thermal instability. Viscous dissipation during cold filament formation produces accompanying hot filaments, which can be searched for in deep Chandra observations of cool-core clusters. In the case of MTI, anisotropic viscosity leads to a nonlinear state with a folded magnetic field structure in which field-line curvature and field strength are anti-correlated. These results demonstrate that, if the HBI and MTI are relevant for shaping the properties of the ICM, one must self-consistently include anisotropic viscosity in order to obtain even qualitatively correct results.

Monitoring of heavy metal concentrations in home outdoor air using moss bags

International Nuclear Information System (INIS)

Rivera, Marcela; Zechmeister, Harald; Medina-Ramon, Mercedes; Basagana, Xavier; Foraster, Maria; Bouso, Laura; Moreno, Teresa; Solanas, Pascual; Ramos, Rafael; Koellensperger, Gunda; Deltell, Alexandre; Vizcaya, David

2011-01-01

One monitoring station is insufficient to characterize the high spatial variation of traffic-related heavy metals within cities. We tested moss bags (Hylocomium splendens), deployed in a dense network, for the monitoring of metals in outdoor air and characterized metals' long-term spatial distribution and its determinants in Girona, Spain. Mosses were exposed outside 23 homes for two months; NO 2 was monitored for comparison. Metals were not highly correlated with NO 2 and showed higher spatial variation than NO 2 . Regression models explained 61-85% of Cu, Cr, Mo, Pb, Sb, Sn, and Zn and 72% of NO 2 variability. Metals were strongly associated with the number of bus lines in the nearest street. Heavy metals are an alternative traffic-marker to NO 2 given their toxicological relevance, stronger association with local traffic and higher spatial variability. Monitoring heavy metals with mosses is appealing, particularly for long-term exposure assessment, as mosses can remain on site many months without maintenance. - Research highlights: → Moss bags can be used to measure the metal's long-term spatial distribution within cities. → Heavy metals in mosses are not highly correlated with ambient NO 2 concentrations. → Heavy metals show higher spatial variation and association with traffic than NO 2 . → Bus lines in the nearest street explain 75-85% of Mo, Cr, Sb, Sn and Cu variability. → Moss bags are useful for long-term at home exposure assessment in epidemiological studies. - The long-term spatial distribution of heavy metals, measured with moss bags, is mainly determined by proximity to bus lines.

Chiral filtration-induced spin/valley polarization in silicene line defects

Science.gov (United States)

Ren, Chongdan; Zhou, Benhu; Sun, Minglei; Wang, Sake; Li, Yunfang; Tian, Hongyu; Lu, Weitao

2018-06-01

The spin/valley polarization in silicene with extended line defects is investigated according to the chiral filtration mechanism. It is shown that the inner-built quantum Hall pseudo-edge states with identical chirality can serve as a chiral filter with a weak magnetic field and that the transmission process is restrained/strengthened for chiral states with reversed/identical chirality. With two parallel line defects, which act as natural chiral filtration, the filter effect is greatly enhanced, and 100% spin/valley polarization can be achieved.

Impact of lining material on chemical and microbial irrigation water quality of Nubaria canal, Egypt

Directory of Open Access Journals (Sweden)

Ahmed Mohamed Azzam

2016-02-01

Full Text Available Objective: To assess the effect of lining material (cement of Nubaria canal (Beheira Governorate, Egypt on its water quality. Methods: Trace metal ions (Fe, Zn, Cu, Pb, and Cd and bacterial indictors for water samples collected from two types of stations (lined and unlined during successive four seasons were analyzed. The effect of lining on bacterial indicators; total viable bacterial count at 22 and 37 °C, total coliform, fecal coliform and fecal streptococci and presence of some bacterial species were studied. Results: Bacterial indicators and trace metals showed seasonal variations, where the highest values were recorded during summer. A significant reduction for Cu (P < 0.05, Zn (P < 0.01 and Cd (P < 0.001 was recorded in lined stations compared to those of unlined ones. Bacterial indicators recorded the lowest counts in lined stations during all seasons, while there was a significant reduction (P < 0.05 between total coliform values (1.70 ± 0.50 in lined stations and unlined ones (3.57 ± 1.01 during summer. Escherichia coli bacteria were predominant in water samples of Nubaria canal, where it recorded 34.4% of bacterial isolates. Conclusions: Lined material plays a role for reducing the bacterial growth and metals concentration, therefore the lining of canal helps in preventing the discharge of sewage pollution into canal.

Underwater tracking of a moving dipole source using an artificial lateral line: algorithm and experimental validation with ionic polymer–metal composite flow sensors

International Nuclear Information System (INIS)

Abdulsadda, Ahmad T; Tan, Xiaobo

2013-01-01

Motivated by the lateral line system of fish, arrays of flow sensors have been proposed as a new sensing modality for underwater robots. Existing studies on such artificial lateral lines (ALLs) have been mostly focused on the localization of a fixed underwater vibrating sphere (dipole source). In this paper we examine the problem of tracking a moving dipole source using an ALL system. Based on an analytical model for the moving dipole-generated flow field, we formulate a nonlinear estimation problem that aims to minimize the error between the measured and model-predicted magnitudes of flow velocities at the sensor sites, which is subsequently solved with the Gauss–Newton scheme. A sliding discrete Fourier transform (SDFT) algorithm is proposed to efficiently compute the evolving signal magnitudes based on the flow velocity measurements. Simulation indicates that it is adequate and more computationally efficient to use only the signal magnitudes corresponding to the dipole vibration frequency. Finally, experiments conducted with an artificial lateral line consisting of six ionic polymer–metal composite (IPMC) flow sensors demonstrate that the proposed scheme is able to simultaneously locate the moving dipole and estimate its vibration amplitude and traveling speed with small errors. (paper)

Weak boson emission in hadron collider processes

International Nuclear Information System (INIS)

Baur, U.

2007-01-01

The O(α) virtual weak radiative corrections to many hadron collider processes are known to become large and negative at high energies, due to the appearance of Sudakov-like logarithms. At the same order in perturbation theory, weak boson emission diagrams contribute. Since the W and Z bosons are massive, the O(α) virtual weak radiative corrections and the contributions from weak boson emission are separately finite. Thus, unlike in QED or QCD calculations, there is no technical reason for including gauge boson emission diagrams in calculations of electroweak radiative corrections. In most calculations of the O(α) electroweak radiative corrections, weak boson emission diagrams are therefore not taken into account. Another reason for not including these diagrams is that they lead to final states which differ from that of the original process. However, in experiment, one usually considers partially inclusive final states. Weak boson emission diagrams thus should be included in calculations of electroweak radiative corrections. In this paper, I examine the role of weak boson emission in those processes at the Fermilab Tevatron and the CERN LHC for which the one-loop electroweak radiative corrections are known to become large at high energies (inclusive jet, isolated photon, Z+1 jet, Drell-Yan, di-boson, tt, and single top production). In general, I find that the cross section for weak boson emission is substantial at high energies and that weak boson emission and the O(α) virtual weak radiative corrections partially cancel

Anisotropic Hanle line shape via magnetothermoelectric phenomena

NARCIS (Netherlands)

Das, Kumar; Dejene, Fasil; van Wees, Bart; Vera Marun, Ivan

2016-01-01

We observe anisotropic Hanle line shape with unequal in-plane and out-of-plane nonlocal signals for spin precession measurements carried out on lateral metallic spin valves with transparent interfaces. The conventional interpretation for this anisotropy corresponds to unequal spin relaxation times

Classical field approach to quantum weak measurements.

Science.gov (United States)

Dressel, Justin; Bliokh, Konstantin Y; Nori, Franco

2014-03-21

By generalizing the quantum weak measurement protocol to the case of quantum fields, we show that weak measurements probe an effective classical background field that describes the average field configuration in the spacetime region between pre- and postselection boundary conditions. The classical field is itself a weak value of the corresponding quantum field operator and satisfies equations of motion that extremize an effective action. Weak measurements perturb this effective action, producing measurable changes to the classical field dynamics. As such, weakly measured effects always correspond to an effective classical field. This general result explains why these effects appear to be robust for pre- and postselected ensembles, and why they can also be measured using classical field techniques that are not weak for individual excitations of the field.

Potential for electropositive metal to reduce the interactions of Atlantic sturgeon with fishing gear.

Science.gov (United States)

Bouyoucos, Ian; Bushnell, Peter; Brill, Richard

2014-02-01

Atlantic sturgeon (Acipenser oxyrhynchus) populations have been declared either endangered or threatened under the U.S. Endangered Species Act. Effective measures to repel sturgeon from fishing gear would be beneficial to both fish and fishers because they could reduce both fishery-associated mortality and the need for seasonal and area closures of specific fisheries. Some chondrostean fishes (e.g., sturgeons and paddlefishes) can detect weak electric field gradients (possibly as low as 5 Μv/cm) due to arrays of electroreceptors (ampullae of Lorenzini) on their snout and gill covers. Weak electric fields, such as those produced by electropositive metals (typically mixtures of the lanthanide elements), could therefore potentially be used as a deterrent. To test this idea, we recorded the behavioral responses of juvenile Atlantic sturgeon (31-43 cm fork length) to electropositive metal (primarily a mixture of the lanthanide elements neodymium and praseodymium) both in the presence and absence of food stimuli. Trials were conducted in an approximately 2.5 m diameter × 0.3 m deep tank, and fish behaviors were recorded with an overhead digital video camera. Video records were subsequently digitized (x, y coordinate system), the distance between the fish and the electropositive metal calculated, and data summarized by compiling frequency distributions with 5-cm bins. Juvenile sturgeon showed clear avoidance of electropositive metal but only when food was present. On the basis of our results, we conclude that the electropositive metals, or other sources of weak electric fields, may eventually be used to reduce the interactions of Atlantic sturgeon with fishing gear, but further investigation is needed. © 2013 Society for Conservation Biology.

Electrooxidative Ruthenium-Catalyzed C-H/O-H Annulation by Weak O-Coordination.

Science.gov (United States)

Qiu, Youai; Tian, Cong; Massignan, Leonardo; Rogge, Torben; Ackermann, Lutz

2018-05-14

Electrocatalysis has been identified as a powerful strategy for organometallic catalysis, and yet electrocatalytic C-H activation is restricted to strongly N-coordinating directing groups. The first example of electrocatalytic C-H activation by weak O-coordination is presented, in which a versatile ruthenium(II) carboxylate catalyst enables electrooxidative C-H/O-H functionalization for alkyne annulations in the absence of metal oxidants; thereby exploiting sustainable electricity as the sole oxidant. Mechanistic insights provide strong support for a facile organometallic C-H ruthenation and an effective electrochemical reoxidation of the key ruthenium(0) intermediate. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Micro-scale metallization on flexible polyimide substrate by Cu electroplating using SU-8 photoresist mask

International Nuclear Information System (INIS)

Cho, S.H.; Kim, S.H.; Lee, N.-E.; Kim, H.M.; Nam, Y.W.

2005-01-01

Technologies for flexible electronics have been developed to make electronic or microelectromechanical (MEMS) devices on inexpensive and flexible organic substrates. In order to fabricate the interconnect lines between device elements or layers in flexible electronic devices, metallization on the flexible substrate is essential. In this case, the width and conductivity of metallization line are very important for minimizing the size of device. Therefore, the realization of metallization process with the scale of a few micrometers on the flexible substrate is required. In this work, micro-scale metallization lines of Cu were fabricated on the flexible substrate by electroplating using the patterned mask of a negative-tone SU-8 photoresist. Polyimide surface was treated by O 2 /Ar atmospheric plasma for the improvement in adhesion between Cr layer and polyimide and in situ sputter deposition of 100-nm-thick Cu seed layers on the sputter-deposited 50-nm-thick Cr adhesion layer was followed. SU-8 photoresist was spin-coated and patterned by photolithography. Electroplating of Cu line, removal of SU-8, and selective wet etch of Cr adhesion and Cu seed layers were carried out. Gap between the Cu lines was successfully filled by spin-coating of polyimide. Micro-scale Cu metal lines with gap filling on the polyimide substrate with a thickness of 6-12 μm and an aspect ratio of 1-3 were successfully fabricated

Integrated-light spectroscopy of globular clusters at the infrared Ca II lines

Science.gov (United States)

Armandroff, Taft E.; Zinn, Robert

1988-01-01

Integrated-light spectroscopy has been obtained for 27 globular clusters at the Ca II IR triplet. Line strengths and radial velocities have been measured from the spectra. For the well-studied clusters in the sample, the strength of the Ca II lines is very well correlated with previous metallicity estimates. Thus, the triplet is useful as a metallicity indicator in globular cluster integrated-light spectra. The greatly reduced effect of interstellar extinction at these wavelengths (compared to the blue region of the spectrum) has permitted observations of some of the most heavily reddened clusters in the Galaxy. For several such clusters, the Ca II triplet metallicities are in poor agreement with metallicity estimates from IR photometry by Malkan (1981). The strength of an interstellar band at 8621A has been used to estimate the amount of extinction towards these clusters. Using the new metallicity and radial-velocity data, the metallicity distribution, kinematics, and spatial distribution of the disk globular cluster system have been analyzed. Results very similar to those of Zinn (1985) have been found. The relation of the disk globulars to the stellar thick disk is discussed.

Refractory thermowell for continuous high temperature measurement of molten metal

International Nuclear Information System (INIS)

Thiesen, T.J.

1992-01-01

This patent describes a vessel for handling molten metal having an interior refractory lining, apparatus for continuous high temperature measurement of the molten metal. It comprises a thermowell; the thermowell containing a multiplicity of thermocouples; leads being coupled to a means for continuously indicating the temperature of the molten metal in the vessel

Generalized fluid equations for parallel transport in collisional to weakly collisional plasmas

International Nuclear Information System (INIS)

Zawaideh, E.S.

1985-01-01

A new set of two-fluid equations which are valid from collisional to weakly collisional limits are derived. Starting from gyrokinetic equations in flux coordinates with no zeroth order drifts, a set of moment equations describing plasma transport along the field lines of a space and time dependent magnetic field are derived. No restriction on the anisotropy of the ion distribution function is imposed. In the highly collisional limit, these equations reduce to those of Braginskii while in the weakly collisional limit, they are similar to the double adiabatic or Chew, Goldberger, and Low (CGL) equations. The new transport equations are used to study the effects of collisionality, magnetic field structure, and plasma anisotropy on plasma parallel transport. Numerical examples comparing these equations with conventional transport equations show that the conventional equations may contain large errors near the sound speed (M approx. = 1). It is also found that plasma anisotropy, which is not included in the conventional equations, is a critical parameter in determining plasma transport in varying magnetic field. The new transport equations are also used to study axial confinement in multiple mirror devices from the strongly to weakly collisional regime. A new ion conduction model was worked out to extend the regime of validity of the transport equations to the low density multiple mirror regime

Peripheral facial weakness (Bell's palsy).

Science.gov (United States)

Basić-Kes, Vanja; Dobrota, Vesna Dermanović; Cesarik, Marijan; Matovina, Lucija Zadro; Madzar, Zrinko; Zavoreo, Iris; Demarin, Vida

2013-06-01

Peripheral facial weakness is a facial nerve damage that results in muscle weakness on one side of the face. It may be idiopathic (Bell's palsy) or may have a detectable cause. Almost 80% of peripheral facial weakness cases are primary and the rest of them are secondary. The most frequent causes of secondary peripheral facial weakness are systemic viral infections, trauma, surgery, diabetes, local infections, tumor, immune disorders, drugs, degenerative diseases of the central nervous system, etc. The diagnosis relies upon the presence of typical signs and symptoms, blood chemistry tests, cerebrospinal fluid investigations, nerve conduction studies and neuroimaging methods (cerebral MRI, x-ray of the skull and mastoid). Treatment of secondary peripheral facial weakness is based on therapy for the underlying disorder, unlike the treatment of Bell's palsy that is controversial due to the lack of large, randomized, controlled, prospective studies. There are some indications that steroids or antiviral agents are beneficial but there are also studies that show no beneficial effect. Additional treatments include eye protection, physiotherapy, acupuncture, botulinum toxin, or surgery. Bell's palsy has a benign prognosis with complete recovery in about 80% of patients, 15% experience some mode of permanent nerve damage and severe consequences remain in 5% of patients.

Metal sorption on kaolinite

International Nuclear Information System (INIS)

Westrich, H.R.; Brady, P.V.; Cygan, R.T.; Nagy, K.L.; Anderson, H.L.

1997-01-01

A key issue in performance assessment of low-level radioactive waste sites is predicting the transport and retardation of radionuclides through local soils under a variety of hydrologic and geochemical conditions. Improved transport codes should include a mechanistic model of radionuclide retardation. The authors have been investigating metal sorption (Cs + , Sr 2+ , and Ba 2+ ) on a simple clay mineral (kaolinite) to better understand the geochemical interactions of common soil minerals with contaminated groundwaters. These studies include detailed characterizations of kaolinite surfaces, experimental adsorption measurements, surface complexation modeling, and theoretical simulations of cation sorption. The aluminol edge (010) site has been identified as the most likely site for metal sorption on kaolinite in natural solutions. Relative metal binding strengths decrease from Ba 2+ to Sr 2+ to Cs + , with some portion sorbed on both kaolinite edges and basal surfaces. Some Cs + also appears to be irreversibly sorbed on both sites. Molecular dynamics simulations suggest that Cs + is sorbed at aluminol (010) edge sites as an inner-sphere complex and weakly sorbed as an outer-sphere complex on (001) basal surfaces. These results provide the basis to understand and predict metal sorption onto kaolinite, and a framework to characterize sorption processes on more complex clay minerals

Weakly oval electron lense

International Nuclear Information System (INIS)

Daumenov, T.D.; Alizarovskaya, I.M.; Khizirova, M.A.

2001-01-01

The method of the weakly oval electrical field getting generated by the axially-symmetrical field is shown. Such system may be designed with help of the cylindric form coaxial electrodes with the built-in quadrupole duplet. The singularity of the indicated weakly oval lense consists of that it provides the conducting both mechanical and electronic adjustment. Such lense can be useful for elimination of the near-axis astigmatism in the electron-optical system

THE SPITZER c2d SURVEY OF WEAK-LINE T TAURI STARS. III. THE TRANSITION FROM PRIMORDIAL DISKS TO DEBRIS DISKS

International Nuclear Information System (INIS)

Wahhaj, Zahed; Cieza, Lucas; Koerner, David W.; Case, April; Stapelfeldt, Karl R.; Chapman, Nicholas; Padgett, Deborah L.; Brooke, Tim; Keller, James R.; MerIn, Bruno; Evans, Neal J.; Harvey, Paul; Sargent, Anneila; Van Dishoeck, Ewine F.; Allen, Lori; Blake, Geoff; Mundy, Lee; Myers, Philip C.

2010-01-01

We present 3.6 to 70 μm Spitzer photometry of 154 weak-line T Tauri stars (WTTSs) in the Chamaeleon, Lupus, Ophiuchus, and Taurus star formation regions, all of which are within 200 pc of the Sun. For a comparative study, we also include 33 classical T Tauri stars which are located in the same star-forming regions. Spitzer sensitivities allow us to robustly detect the photosphere in the IRAC bands (3.6 to 8 μm) and the 24 μm MIPS band. In the 70 μm MIPS band, we are able to detect dust emission brighter than roughly 40 times the photosphere. These observations represent the most sensitive WTTSs survey in the mid- to far-infrared to date and reveal the frequency of outer disks (r = 3-50 AU) around WTTSs. The 70 μm photometry for half the c2d WTTSs sample (the on-cloud objects), which were not included in the earlier papers in this series, those of Padgett et al. and Cieza et al., are presented here for the first time. We find a disk frequency of 19% for on-cloud WTTSs, but just 5% for off-cloud WTTSs, similar to the value reported in the earlier works. WTTSs exhibit spectral energy distributions that are quite diverse, spanning the range from optically thick to optically thin disks. Most disks become more tenuous than L disk /L * = 2 x 10 -3 in 2 Myr and more tenuous than L disk /L * = 5 x 10 -4 in 4 Myr.

Design of conveyor utilization monitoring system: a case study of powder coating line in sheet metal fabrication

Science.gov (United States)

Prasetyo, Hoedi; Sugiarto, Yohanes; Nur Rosyidi, Cucuk

2018-03-01

Conveyor is a very useful equipment to replace manpower in transporting the goods. It highly influences the productivity, production capacity utilization and eventually the production cost. This paper proposes a system to monitor the utilization of conveyor at a low cost through a case study at powder coating process line in a sheet metal fabrication. Preliminary observation was conducted to identify the problems. The monitoring system was then built and executed. The system consists of two sub systems. First is sub system for collecting and transmitting the required data and the second is sub system for displaying the data. The system utilizes sensors, wireless data transfer and windows-based application. The test results showed that the whole system works properly. By this system, the productivity and status of the conveyor can be monitored in real time. This research enriches the development of conveyor monitoring system especially for implementation in small and medium enterprises.

The signal of weak gravitational lensing from galaxy groups and clusters

Science.gov (United States)

Markert, Sean

2017-02-01

The weak gravitational lensing of galaxy clusters is a valuable tool. The deflection of light around a lens is solely dependent on the underlying distribution of foreground mass, and independent of tracers of mass such as the mass to light ratio and kinematics. As a direct probe of mass, weak lensing serves as an independent calibration of mass-observable relationships. These massive clusters are objects of great interest to astronomers, as their abundance is dependent on the conditions of the early universe, and accurate counts of clusters serve as a test of cosmological model. Upcoming surveys, such as LSST and DES, promise to push the limit of observable weak lensing, detecting clusters and sources at higher redshift than has ever been detected before. This makes accurate counts of clusters of a given mass and redshift, and proper calibration of mass-observable relationships, vital to cosmological studies. We used M> 1013.5 h-1M ⊙ halos from the MultiDark Planck simulation at z 0.5 to study the behavior of the reduced shear in clusters. We generated 2D maps of convergence and shear the halos using the GLAMER lensing library. Using these maps, we simulated observations of randomly placed background sources, and generate azimuthal averages of the shear. This reduced shear profile, and the true reduced shear profile of the halo, is fit using analytical solutions for shear of the NFW, Einasto, and truncated NFW density profile. The masses of these density profiles are then compared to the total halo masses from the halo catalogs. We find that fits to the reduced shear for halos extending past ≈ 2 h-1Mpc are fits to the noise of large scale structure along the line of sight. This noise is largely in the 45° rotated component to the reduced tangential shear, and is a breakdown in the approximation of gtan ≈ gnot required for density profile fitting of clusters. If fits are constrained to a projected radii of < 2 h-1Mpc, we see massively improved fits

Weak decays of stable particles

International Nuclear Information System (INIS)

Brown, R.M.

1988-09-01

In this article we review recent advances in the field of weak decays and consider their implications for quantum chromodynamics (the theory of strong interactions) and electroweak theory (the combined theory of electromagnetic and weak interactions), which together form the ''Standard Model'' of elementary particles. (author)

Weak lensing and dark energy

International Nuclear Information System (INIS)

Huterer, Dragan

2002-01-01

We study the power of upcoming weak lensing surveys to probe dark energy. Dark energy modifies the distance-redshift relation as well as the matter power spectrum, both of which affect the weak lensing convergence power spectrum. Some dark-energy models predict additional clustering on very large scales, but this probably cannot be detected by weak lensing alone due to cosmic variance. With reasonable prior information on other cosmological parameters, we find that a survey covering 1000 sq deg down to a limiting magnitude of R=27 can impose constraints comparable to those expected from upcoming type Ia supernova and number-count surveys. This result, however, is contingent on the control of both observational and theoretical systematics. Concentrating on the latter, we find that the nonlinear power spectrum of matter perturbations and the redshift distribution of source galaxies both need to be determined accurately in order for weak lensing to achieve its full potential. Finally, we discuss the sensitivity of the three-point statistics to dark energy

Biases in Metallicity Measurements from Global Galaxy Spectra: The Effects of Flux Weighting and Diffuse Ionized Gas Contamination

Science.gov (United States)

Sanders, Ryan L.; Shapley, Alice E.; Zhang, Kai; Yan, Renbin

2017-12-01

Galaxy metallicity scaling relations provide a powerful tool for understanding galaxy evolution, but obtaining unbiased global galaxy gas-phase oxygen abundances requires proper treatment of the various line-emitting sources within spectroscopic apertures. We present a model framework that treats galaxies as ensembles of H II and diffuse ionized gas (DIG) regions of varying metallicities. These models are based upon empirical relations between line ratios and electron temperature for H II regions, and DIG strong-line ratio relations from SDSS-IV MaNGA IFU data. Flux-weighting effects and DIG contamination can significantly affect properties inferred from global galaxy spectra, biasing metallicity estimates by more than 0.3 dex in some cases. We use observationally motivated inputs to construct a model matched to typical local star-forming galaxies, and quantify the biases in strong-line ratios, electron temperatures, and direct-method metallicities as inferred from global galaxy spectra relative to the median values of the H II region distributions in each galaxy. We also provide a generalized set of models that can be applied to individual galaxies or galaxy samples in atypical regions of parameter space. We use these models to correct for the effects of flux-weighting and DIG contamination in the local direct-method mass-metallicity and fundamental metallicity relations, and in the mass-metallicity relation based on strong-line metallicities. Future photoionization models of galaxy line emission need to include DIG emission and represent galaxies as ensembles of emitting regions with varying metallicity, instead of as single H II regions with effective properties, in order to obtain unbiased estimates of key underlying physical properties.

A general nonlinear magnetomechanical model for ferromagnetic materials under a constant weak magnetic field

Energy Technology Data Exchange (ETDEWEB)

Shi, Pengpeng; Zheng, Xiaojing, E-mail: xjzheng@xidian.edu.cn [School of Mechano-Electronic Engineering, Xidian University, Xi' an 710071, Shaanxi (China); Jin, Ke [School of Aerospace Science and Technology, Xidian University, Xi' an 710071, Shaanxi (China)

2016-04-14

Weak magnetic nondestructive testing (e.g., metal magnetic memory method) concerns the magnetization variation of ferromagnetic materials due to its applied load and a weak magnetic surrounding them. One key issue on these nondestructive technologies is the magnetomechanical effect for quantitative evaluation of magnetization state from stress–strain condition. A representative phenomenological model has been proposed to explain the magnetomechanical effect by Jiles in 1995. However, the Jiles' model has some deficiencies in quantification, for instance, there is a visible difference between theoretical prediction and experimental measurements on stress–magnetization curve, especially in the compression case. Based on the thermodynamic relations and the approach law of irreversible magnetization, a nonlinear coupled model is proposed to improve the quantitative evaluation of the magnetomechanical effect. Excellent agreement has been achieved between the predictions from the present model and previous experimental results. In comparison with Jiles' model, the prediction accuracy is improved greatly by the present model, particularly for the compression case. A detailed study has also been performed to reveal the effects of initial magnetization status, cyclic loading, and demagnetization factor on the magnetomechanical effect. Our theoretical model reveals that the stable weak magnetic signals of nondestructive testing after multiple cyclic loads are attributed to the first few cycles eliminating most of the irreversible magnetization. Remarkably, the existence of demagnetization field can weaken magnetomechanical effect, therefore, significantly reduces the testing capability. This theoretical model can be adopted to quantitatively analyze magnetic memory signals, and then can be applied in weak magnetic nondestructive testing.

VERY METAL-POOR STARS IN THE OUTER GALACTIC BULGE FOUND BY THE APOGEE SURVEY

International Nuclear Information System (INIS)

García Pérez, Ana E.; Majewski, Steven R.; Hearty, Fred R.; Cunha, Katia; Shetrone, Matthew; Johnson, Jennifer A.; Zasowski, Gail; Smith, Verne V.; Beers, Timothy C.; Schiavon, Ricardo P.; Holtzman, Jon; Nidever, David; Allende Prieto, Carlos; Bizyaev, Dmitry; Ebelke, Garrett; Malanushenko, Elena; Malanushenko, Viktor; Eisenstein, Daniel J.; Frinchaboy, Peter M.; Girardi, Léo

2013-01-01

Despite its importance for understanding the nature of early stellar generations and for constraining Galactic bulge formation models, at present little is known about the metal-poor stellar content of the central Milky Way. This is a consequence of the great distances involved and intervening dust obscuration, which challenge optical studies. However, the Apache Point Observatory Galactic Evolution Experiment (APOGEE), a wide-area, multifiber, high-resolution spectroscopic survey within Sloan Digital Sky Survey III, is exploring the chemistry of all Galactic stellar populations at infrared wavelengths, with particular emphasis on the disk and the bulge. An automated spectral analysis of data on 2403 giant stars in 12 fields in the bulge obtained during APOGEE commissioning yielded five stars with low metallicity ([Fe/H] ≤ –1.7), including two that are very metal-poor [Fe/H] ∼ –2.1 by bulge standards. Luminosity-based distance estimates place the 5 stars within the outer bulge, where 1246 of the other analyzed stars may reside. A manual reanalysis of the spectra verifies the low metallicities, and finds these stars to be enhanced in the α-elements O, Mg, and Si without significant α-pattern differences with other local halo or metal-weak thick-disk stars of similar metallicity, or even with other more metal-rich bulge stars. While neither the kinematics nor chemistry of these stars can yet definitively determine which, if any, are truly bulge members, rather than denizens of other populations co-located with the bulge, the newly identified stars reveal that the chemistry of metal-poor stars in the central Galaxy resembles that of metal-weak thick-disk stars at similar metallicity.

VERY METAL-POOR STARS IN THE OUTER GALACTIC BULGE FOUND BY THE APOGEE SURVEY

Energy Technology Data Exchange (ETDEWEB)

Garcia Perez, Ana E.; Majewski, Steven R.; Hearty, Fred R. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Cunha, Katia [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Shetrone, Matthew [McDonald Observatory, University of Texas at Austin, Fort Davis, TX 79734 (United States); Johnson, Jennifer A.; Zasowski, Gail [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States); Smith, Verne V.; Beers, Timothy C. [National Optical Astronomy Observatories, Tucson, AZ 85719 (United States); Schiavon, Ricardo P. [Gemini Observatory, 670 N. A' Ohoku Place, Hilo, HI 96720 (United States); Holtzman, Jon [Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003 (United States); Nidever, David [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Allende Prieto, Carlos [Departamento de Astrofisica, Universidad de La Laguna, E-38206 La Laguna, Tenerife (Spain); Bizyaev, Dmitry; Ebelke, Garrett; Malanushenko, Elena; Malanushenko, Viktor [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Eisenstein, Daniel J. [Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Frinchaboy, Peter M. [Department of Physics and Astronomy, Texas Christian University, 2800 South University Drive, Fort Worth, TX 76129 (United States); Girardi, Leo [Laboratorio Interinstitucional de e-Astronomia - LIneA, Rua Gal. Jose Cristino 77, Rio de Janeiro, RJ - 20921-400 (Brazil); and others

2013-04-10

Despite its importance for understanding the nature of early stellar generations and for constraining Galactic bulge formation models, at present little is known about the metal-poor stellar content of the central Milky Way. This is a consequence of the great distances involved and intervening dust obscuration, which challenge optical studies. However, the Apache Point Observatory Galactic Evolution Experiment (APOGEE), a wide-area, multifiber, high-resolution spectroscopic survey within Sloan Digital Sky Survey III, is exploring the chemistry of all Galactic stellar populations at infrared wavelengths, with particular emphasis on the disk and the bulge. An automated spectral analysis of data on 2403 giant stars in 12 fields in the bulge obtained during APOGEE commissioning yielded five stars with low metallicity ([Fe/H] {<=} -1.7), including two that are very metal-poor [Fe/H] {approx} -2.1 by bulge standards. Luminosity-based distance estimates place the 5 stars within the outer bulge, where 1246 of the other analyzed stars may reside. A manual reanalysis of the spectra verifies the low metallicities, and finds these stars to be enhanced in the {alpha}-elements O, Mg, and Si without significant {alpha}-pattern differences with other local halo or metal-weak thick-disk stars of similar metallicity, or even with other more metal-rich bulge stars. While neither the kinematics nor chemistry of these stars can yet definitively determine which, if any, are truly bulge members, rather than denizens of other populations co-located with the bulge, the newly identified stars reveal that the chemistry of metal-poor stars in the central Galaxy resembles that of metal-weak thick-disk stars at similar metallicity.

Graphene on metal surfaces and its hydrogen adsorption

DEFF Research Database (Denmark)

Andersen, Mie; Hornekær, L.; Hammer, B.

2012-01-01

The interaction of graphene with various metal surfaces is investigated using density functional theory and the meta-generalized gradient approximation (MGGA) M06-L functional. We demonstrate that this method is of comparable accuracy to the random-phase approximation (RPA). With M06-L we study...... large systems inaccessible to RPA with H adsorbed on graphene on a selected strongly (Ni) and a selected weakly (Pt) interacting substrate. Very stable graphane-like clusters, where every other C atom binds to a H atom above and every other to a metal atom below, are found on both substrates...

Monitoring of heavy metal concentrations in home outdoor air using moss bags

Energy Technology Data Exchange (ETDEWEB)

Rivera, Marcela, E-mail: arivera@creal.ca [Centre for Research in Environmental Epidemiology CREAL, Barcelona (Spain); Municipal Institute of Medical Research (IMIM-Hospital del Mar), Barcelona (Spain); Universitat Pompeu Fabra, Barcelona (Spain); CIBER Epidemiologia y Salud Publica (CIBERESP) (Spain); Zechmeister, Harald [University of Vienna, Faculty of Life Sciences, Vienna (Austria); Medina-Ramon, Mercedes; Basagana, Xavier [Centre for Research in Environmental Epidemiology CREAL, Barcelona (Spain); Municipal Institute of Medical Research (IMIM-Hospital del Mar), Barcelona (Spain); CIBER Epidemiologia y Salud Publica (CIBERESP) (Spain); Foraster, Maria [Centre for Research in Environmental Epidemiology CREAL, Barcelona (Spain); Municipal Institute of Medical Research (IMIM-Hospital del Mar), Barcelona (Spain); Universitat Pompeu Fabra, Barcelona (Spain); CIBER Epidemiologia y Salud Publica (CIBERESP) (Spain); Bouso, Laura [Centre for Research in Environmental Epidemiology CREAL, Barcelona (Spain); Municipal Institute of Medical Research (IMIM-Hospital del Mar), Barcelona (Spain); CIBER Epidemiologia y Salud Publica (CIBERESP) (Spain); Moreno, Teresa [Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona (Spain); Solanas, Pascual; Ramos, Rafael [Research Unit, Family Medicine, Girona, Jordi Gol Institute for Primary Care Research (IDIAP Jordi Gol), Catalan Institute of Health, Catalunya (Spain); Department of Medical Sciences, School of Medicine, University of Girona (Spain); Koellensperger, Gunda [University of Natural Resources and Applied Life Sciences, Vienna (Austria); Deltell, Alexandre [Polytechnic School, GREFEMA, University of Girona (Spain); Vizcaya, David [Centre for Research in Environmental Epidemiology CREAL, Barcelona (Spain); Municipal Institute of Medical Research (IMIM-Hospital del Mar), Barcelona (Spain); Universitat Pompeu Fabra, Barcelona (Spain); CIBER Epidemiologia y Salud Publica (CIBERESP) (Spain)

2011-04-15

One monitoring station is insufficient to characterize the high spatial variation of traffic-related heavy metals within cities. We tested moss bags (Hylocomium splendens), deployed in a dense network, for the monitoring of metals in outdoor air and characterized metals' long-term spatial distribution and its determinants in Girona, Spain. Mosses were exposed outside 23 homes for two months; NO{sub 2} was monitored for comparison. Metals were not highly correlated with NO{sub 2} and showed higher spatial variation than NO{sub 2}. Regression models explained 61-85% of Cu, Cr, Mo, Pb, Sb, Sn, and Zn and 72% of NO{sub 2} variability. Metals were strongly associated with the number of bus lines in the nearest street. Heavy metals are an alternative traffic-marker to NO{sub 2} given their toxicological relevance, stronger association with local traffic and higher spatial variability. Monitoring heavy metals with mosses is appealing, particularly for long-term exposure assessment, as mosses can remain on site many months without maintenance. - Research highlights: > Moss bags can be used to measure the metal's long-term spatial distribution within cities. > Heavy metals in mosses are not highly correlated with ambient NO{sub 2} concentrations. > Heavy metals show higher spatial variation and association with traffic than NO{sub 2}. > Bus lines in the nearest street explain 75-85% of Mo, Cr, Sb, Sn and Cu variability. > Moss bags are useful for long-term at home exposure assessment in epidemiological studies. - The long-term spatial distribution of heavy metals, measured with moss bags, is mainly determined by proximity to bus lines.

Anomalous diffusion and Levy random walk of magnetic field lines in three dimensional turbulence

International Nuclear Information System (INIS)

Zimbardo, G.; Veltri, P.; Basile, G.; Principato, S.

1995-01-01

The transport of magnetic field lines is studied numerically where three dimensional (3-D) magnetic fluctuations, with a power law spectrum, and periodic over the simulation box are superimposed on an average uniform magnetic field. The weak and the strong turbulence regime, δB∼B 0 , are investigated. In the weak turbulence case, magnetic flux tubes are separated from each other by percolating layers in which field lines undergo a chaotic motion. In this regime the field lines may exhibit Levy, rather than Gaussian, random walk, changing from Levy flights to trapped motion. The anomalous diffusion laws left-angle Δx 2 i right-angle ∝s α with α>1 and α<1, are obtained for a number of cases, and the non-Gaussian character of the field line random walk is pointed out by computing the kurtosis. Increasing the fluctuation level, and, therefore stochasticity, normal diffusion (α congruent 1) is recovered and the kurtoses reach their Gaussian value. However, the numerical results show that neither the quasi-linear theory nor the two dimensional percolation theory can be safely extrapolated to the considered 3-D strong turbulence regime. copyright 1995 American Institute of Physics

Heavy metal-induced gene expression in fish and fish cell lines

International Nuclear Information System (INIS)

Price-Haughey, J.; Bonham, K.; Gedamu, L.

1986-01-01

Two isoforms of metallothionein (MT) have been isolated from rainbow trout livers following CdCl 2 injections. These MTs have been identified by standard procedures and appear to be similar to mammalian MTs. Total RNA from such induced livers was shown to contain high levels of MT-mRNA activity when translated in cell free systems. This activity was demonstrated to be in the 8 to 10S region of a sucrose gradient. The RNA fractions also showed homology to a mouse MT-I cDNA probe. The exposure of rainbow trout hepatoma (RTH) cells to various concentrations of CdCl 2 and ZnCl 2 induced the expression of MT and MT-mRNA. Exposure of Chinook salmon embryonic (CHSE) cells to these metals, however, did not result in MT synthesis, suggesting that the MT genes have not become committed to transcription. Instead, an unknown low molecular weight (MW = 14 kDa) protein was induced. This metal-inducible protein (MIP) was capable of binding 109 Cd and was stable to heating, while the binding of the metal to this protein was not. These characteristics have been reported for a protein induced in rainbow trout liver following environmental exposure to cadmium

Recovery of uranium and lining material from magnesium fluoride slag at UMP

International Nuclear Information System (INIS)

Bandyopadhyay, P.K.; Singh, H.; Shadakshari, B.M.; Meghal, A.M.

1991-01-01

At Uranium Metal Plant, uranium metal is produced by reduction of UF 4 with magnesium metal, in a closed reactor lined with refractory MgF 2 lining material. During this reduction, more MgF 2 is produced as the slag. This slag generally contains 2-4% uranium and hence is processed to recover these values and part of the slag, free from uranium is reused for lining the reactor. This paper describes the process parameters finalised for crushing and grinding of the slag and for leaching uranium with nitric acid. The leach liquor contains appreciable amount of fluoride and hence is processed through a separate solvent extraction cycle with tributyl phosphate. The resultant purified uranyl nitrate solution is mixed with the main stream crude solution for final purification. The conditions optimised for the solvent extraction step, the problems faced during the regular operation over the last few years and the experience gained are described. An outline of the scheme to treat larger quantities of the slag on a regular basis is presented. (author). 6 refs., 1 fig., 1 tab

Weak self-adjoint differential equations

International Nuclear Information System (INIS)

Gandarias, M L

2011-01-01

The concepts of self-adjoint and quasi self-adjoint equations were introduced by Ibragimov (2006 J. Math. Anal. Appl. 318 742-57; 2007 Arch. ALGA 4 55-60). In Ibragimov (2007 J. Math. Anal. Appl. 333 311-28), a general theorem on conservation laws was proved. In this paper, we generalize the concept of self-adjoint and quasi self-adjoint equations by introducing the definition of weak self-adjoint equations. We find a class of weak self-adjoint quasi-linear parabolic equations. The property of a differential equation to be weak self-adjoint is important for constructing conservation laws associated with symmetries of the differential equation. (fast track communication)

Full-wave analysis using a tangential vector finite-element formulation of arbitrary cross-section transmission lines for millimeter and microwave applications

Science.gov (United States)

Helal, M.; Legier, J. F.; Pribetich, P.; Kennis, P.

1994-06-01

A tangential vector finite-element formulation is implemented to deal with arbitrary cross section and metallic strip shape. Classical planar transmission lines as well as nonconventional cross-section waveguides such as the new microshield line are treated. Effects on propagation characteristics for these lines are studied when the metallization shape is approximated by a lossy trapezoid area.

Evaluation of cyclonic ash, commercial Na-silicates, lime and phosphoric acid for metal immobilisation purposes in contaminated soils in Flanders (Belgium)

International Nuclear Information System (INIS)

Geebelen, Wouter; Sappin-Didier, Valerie; Ruttens, Ann; Carleer, Robert; Yperman, Jan; Bongue-Boma, Kwele; Mench, Michel; Lelie, Niels van der; Vangronsveld, Jaco

2006-01-01

In order to reduce the health risks associated with historically enriched metal smelting sites in Flanders (Belgium), the capacities of a non-beringite cyclonic ash and commercial Na-silicates to fix metals and create conditions to restore vegetation cover were evaluated and compared to lime and H 3 PO 4 . All tested amendments reduced Ca(NO 3 ) 2 -extractable soil metal concentrations and reduced metal uptake in Agrostis capillaris seedlings. Sodium released by Na-silicates was possibly toxic to bean plants while an isotopic dilution technique revealed that metals were only weakly sorbed by silicates (i.e. reversible sorption). Cyclonic ash appeared more efficient than lime in both reducing oxidative stress in beans and Zn, Cu and Pb uptake in grasses. The metal fixing mechanism for both amendments appeared similar (i.e. irreversible fixation at constant pH), in contrast to H 3 PO 4 where at least part of the immobilised Cd was irreversibly fixed across a range of pH. - Metal immobilising capacities of Na-silicates are weak, while the active mechanism of cyclonic ash is the same as lime

Quantum discord with weak measurements

International Nuclear Information System (INIS)

Singh, Uttam; Pati, Arun Kumar

2014-01-01

Weak measurements cause small change to quantum states, thereby opening up the possibility of new ways of manipulating and controlling quantum systems. We ask, can weak measurements reveal more quantum correlation in a composite quantum state? We prove that the weak measurement induced quantum discord, called as the “super quantum discord”, is always larger than the quantum discord captured by the strong measurement. Moreover, we prove the monotonicity of the super quantum discord as a function of the measurement strength and in the limit of strong projective measurement the super quantum discord becomes the normal quantum discord. We find that unlike the normal discord, for pure entangled states, the super quantum discord can exceed the quantum entanglement. Our results provide new insights on the nature of quantum correlation and suggest that the notion of quantum correlation is not only observer dependent but also depends on how weakly one perturbs the composite system. We illustrate the key results for pure as well as mixed entangled states. -- Highlights: •Introduced the role of weak measurements in quantifying quantum correlation. •We have introduced the notion of the super quantum discord (SQD). •For pure entangled state, we show that the SQD exceeds the entanglement entropy. •This shows that quantum correlation depends not only on observer but also on measurement strength

Large patternable metal nanoparticle sheets by photo/e-beam lithography

Science.gov (United States)

Saito, Noboru; Wang, Pangpang; Okamoto, Koichi; Ryuzaki, Sou; Tamada, Kaoru

2017-10-01

Techniques for micro/nano-scale patterning of large metal nanoparticle sheets can potentially be used to realize high-performance photoelectronic devices because the sheets provide greatly enhanced electrical fields around the nanoparticles due to localized surface plasmon resonances. However, no single metal nanoparticle sheet currently exists with sufficient durability for conventional lithographical processes. Here, we report large photo and/or e-beam lithographic patternable metal nanoparticle sheets with improved durability by incorporating molecular cross-linked structures between nanoparticles. The cross-linked structures were easily formed by a one-step chemical reaction; immersing a single nanoparticle sheet consisting of core metals, to which capping molecules ionically bond, in a dithiol ethanol solution. The ligand exchange reaction processes were discussed in detail, and we demonstrated 20 μm wide line and space patterns, and a 170 nm wide line of the silver nanoparticle sheets.

Spin effects in the weak interaction

International Nuclear Information System (INIS)

Freedman, S.J.; Chicago Univ., IL; Chicago Univ., IL

1990-01-01

Modern experiments investigating the beta decay of the neutron and light nuclei are still providing important constraints on the theory of the weak interaction. Beta decay experiments are yielding more precise values for allowed and induced weak coupling constants and putting constraints on possible extensions to the standard electroweak model. Here we emphasize the implications of recent experiments to pin down the strengths of the weak vector and axial vector couplings of the nucleon

Weak interactions in astrophysics and cosmology

International Nuclear Information System (INIS)

Taylor, R.J.

1977-01-01

There ar many problems in astrophysics and cosmology in which the form of the weak interactions, their strength or the number of weakly interacting particles, is very important. It is possible that astronomical observations may give some information about the weak interactions. In the conventional hot big bang cosmological theory the number of leptons with associated neutrinos influences the speed of expansion of the Universe and the chemical composition of pre-galactic matter. The strength of the weak interaction, as exemplified by the half-life of the neutron, has a similar effect. In addition, the form of the weak interactions will determine how effectively neutrino viscosity can smooth out irregularities in the early Universe. Because neutrinos have a very long mean free path, they can escape from the central region of stars whereas photons can only escape from the surface. In late stages of stellar evolution, neutrino luminosity is often believed to be much greater than photon luminosity. This can both accelerate the cooling of dying stars and influence the stages of stellar evolution leading to the onset of supernova explosions. In pre-super-novae it is even possible that very dense stellar cores can be opaque to neutrinos and that the absorption or scattering of neutrinos can cause the explosion. These results depend crucially on the form of the weak interactions, with the discovery of neutral currents being very important. Until the solar neutrino experiment has been reconciled with theory, the possible role of uncertainties in the weak interactions cannot be ignored. (author)

RADIO-WEAK BL LAC OBJECTS IN THE FERMI ERA

Energy Technology Data Exchange (ETDEWEB)

Massaro, F.; Marchesini, E. J. [Dipartimento di Fisica, Università degli Studi di Torino (UniTO), via Pietro Giuria 1, I-10125 Torino (Italy); D’Abrusco, R.; Smith, Howard A. [Smithsonian Astrophysical Observatory, 60 Garden Street, 02138 Cambridge, MA (United States); Masetti, N. [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, via Gobetti 101, I-40129, Bologna (Italy); Andruchow, I. [Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque, B1900FWA, La Plata (Argentina)

2017-01-10

The existence of “radio-weak BL Lac objects” (RWBLs) has been an open question, and has remained unsolved since the discovery that quasars could be radio-quiet or radio-loud. Recently, several groups identified RWBL candidates, mostly found while searching for low-energy counterparts of the unidentified or unassociated gamma-ray sources listed in the Fermi catalogs. Confirming RWBLs is a challenging task since they could be confused with white dwarfs (WDs) or weak emission line quasars (WELQs) when there are not sufficient data to precisely draw their broadband spectral energy distribution, and their classification is mainly based on a featureless optical spectra. Motivated by the recent discovery that Fermi BL Lacs appear to have very peculiar mid-IR emission, we show that it is possible to distinguish between WDs, WELQs, and BL Lacs using the [3.4]–[4.6]–[12] μ m color–color plot built using the WISE magnitudes when the optical spectrum is available. On the basis of this analysis, we identify WISE J064459.38+603131 and WISE J141046.00+740511.2 as the first two genuine RWBLs, both potentially associated with Fermi sources. Finally, to strengthen our identification of these objects as true RWBLs, we present multifrequency observations for these two candidates to show that their spectral behavior is indeed consistent with that of the BL Lac population.

RADIO-WEAK BL LAC OBJECTS IN THE FERMI ERA

International Nuclear Information System (INIS)

Massaro, F.; Marchesini, E. J.; D’Abrusco, R.; Smith, Howard A.; Masetti, N.; Andruchow, I.

2017-01-01

The existence of “radio-weak BL Lac objects” (RWBLs) has been an open question, and has remained unsolved since the discovery that quasars could be radio-quiet or radio-loud. Recently, several groups identified RWBL candidates, mostly found while searching for low-energy counterparts of the unidentified or unassociated gamma-ray sources listed in the Fermi catalogs. Confirming RWBLs is a challenging task since they could be confused with white dwarfs (WDs) or weak emission line quasars (WELQs) when there are not sufficient data to precisely draw their broadband spectral energy distribution, and their classification is mainly based on a featureless optical spectra. Motivated by the recent discovery that Fermi BL Lacs appear to have very peculiar mid-IR emission, we show that it is possible to distinguish between WDs, WELQs, and BL Lacs using the [3.4]–[4.6]–[12] μ m color–color plot built using the WISE magnitudes when the optical spectrum is available. On the basis of this analysis, we identify WISE J064459.38+603131 and WISE J141046.00+740511.2 as the first two genuine RWBLs, both potentially associated with Fermi sources. Finally, to strengthen our identification of these objects as true RWBLs, we present multifrequency observations for these two candidates to show that their spectral behavior is indeed consistent with that of the BL Lac population.

Supporting Product Line Evolution with Framed Aspects

DEFF Research Database (Denmark)

Loughran, Neil; Rashid, Awais; Zhang, Weishan

2004-01-01

, but there will eventually come a time when a certain feature or scenario appears which could not have been foreseen in the early stages of development. We argue that frames and aspects when used in isolation cannot overcome these weaknesses effectively. However, they can be addressed by using the respective strengths......This paper discusses how evolution in software product lines can be supported using framed aspects: a combination of aspect-oriented programming and frame technology. Product line architectures and assets are subject to maintenance and evolution throughout their lifetime due to the emergence of new...... of both technologies in combination. The amalgamation of framing and aspect-oriented techniques can help in the integration of new features and thus reduce the risk of architectural erosion....

Impaired microbial activity caused by metal pollution: A field study in a deactivated uranium mining area

International Nuclear Information System (INIS)

Antunes, Sara Cristina; Pereira, Ruth; Marques, Sérgio Miguel; Castro, Bruno Branco; Gonçalves, Fernando

2011-01-01

European frameworks for the ecological risk assessment (ERA) of contaminated sites integrate information from three lines of evidence: chemical, ecotoxicological, and ecological. Regarding the last one, field observations at the contaminated sites are compared to reference site(s) and the differences recorded are analysed at the light of a cause-effect relationship, taking into account the site-specific contamination. Thus, included in the tier 2 of a site-specific risk assessment that is being carried out in an deactivated uranium mining area, a battery of soil enzyme activities (dehydrogenases, urease, arysulphatase, cellulase, acid phosphate) and potential nitrification were assessed in seven sampling sites (A–D–E–F–G–H–I) at different distances from the mine pit. These parameters have been considered good indicators of impacts on soil microbial communities and, subsequently, on soil functions. Soil enzyme activities were impaired in the most contaminated site (A, near the mine pit), for which a higher degree of risk was determined in the tier 1 of ERA. Three other sites within the mining area (F, G, and D) were discriminated on the basis of their low microbial activity, using uni- and multivariate approaches, and validating what had been previously found with chemical and ecotoxicological lines of evidence. We observed considerable among-site heterogeneity in terms of soil physical and chemical properties, combined with seasonal differences in enzyme activities. Still, the correlation between microbial parameters and soil general physical and chemical parameters was weak. In opposition, significant and negative correlations were found between soil enzyme activities and several metallic elements (Al, Be, Cu, U). These findings suggest a clear correlation between compromised soil function (nutrient recycling) and metal contamination. Such information reinforces the evidence of risks for some sites within the mining area and is an important

Mechanical design of injection line for VEC

International Nuclear Information System (INIS)

Nandi, C.; Bandopadhyay, D.K.; Pal, G.; Sharma, R.N.; Mallik, C.; Chaudhuri, J.; Bhandari, R.K.

2003-01-01

A 14.5 GHz ECR ion source along with its analyzing section was earlier installed at VECC for injecting multiply charged gaseous and metallic ions into the existing K 130 cyclotron. The injection line from this ECR ion source was connected to the vertical section of the existing injection line for integrating it with the K 130 cyclotron. The injection line comprises two solenoid magnets, a steering magnet, and a bending magnet. In between the solenoid magnets a length about 1.5 metres has been provided for future atomic physics experimental applications. Two gate valves are used to isolate this area. For beam diagnostics, two Faraday cups, designed and fabricated in this centre, have been installed

Characterizing Corrosion Effects of Weak Organic Acids Using a Modified Bono Test

Science.gov (United States)

Zhou, Yuqin; Turbini, Laura J.; Ramjattan, Deepchand; Christian, Bev; Pritzker, Mark

2013-12-01

To meet environmental requirements and achieve benefits of cost-effective manufacturing, no-clean fluxes (NCFs) or low-solids fluxes have become popular in present electronic manufacturing processes. Weak organic acids (WOAs) as the activation ingredients in NCFs play an important role, especially in the current lead-free and halogen-free soldering technology era. However, no standard or uniform method exists to characterize the corrosion effects of WOAs on actual metallic circuits of printed wiring boards (PWBs). Hence, the development of an effective quantitative test method for evaluating the corrosion effects of WOAs on the PWB's metallic circuits is imperative. In this paper, the modified Bono test, which was developed to quantitatively examine the corrosion properties of flux residues, is used to characterize the corrosion effects of five WOAs (i.e., abietic acid, succinic acid, glutaric acid, adipic acid, and malic acid) on PWB metallic circuits. Experiments were performed under three temperature/humidity conditions (85°C/85% RH, 60°C/93% RH, and 40°C/93% RH) using two WOA solution concentrations. The different corrosion effects among the various WOAs were best reflected in the testing results at 40°C and 60°C. Optical microscopy was used to observe the morphology of the corroded copper tracks, and scanning electron microscopy (SEM) energy-dispersive x-ray (EDX) characterization was performed to determine the dendrite composition.

Crossover to Fermi-liquid behavior for weakly-coupled Luttinger liquids in the anisotropic large-dimension limit

OpenAIRE

Arrigoni, E.

1999-01-01

We study the problem of the crossover from one- to higher-dimensional metals by considering an array of Luttinger liquids (one-dimensional chains) coupled by a weak interchain hopping {\\tp.} We evaluate the exact asymptotic low-energy behavior of the self-energy in the anisotropic infinite-dimension limit. This limit extends the dinamical mean field concept to the case of a chain embedded in a self-consistent medium. The system flows to a Fermi-liquid fixed point for energies below the dimens...

Mass loss, levitation, accretion, and the sharp-lined features in hot white dwarfs

International Nuclear Information System (INIS)

Bruhweiler, F.C.; Kondo, Y.

1983-01-01

We have studied eight white dwarfs, seven DA and one He-rich types, observed at a high resolution (lambda/Δlambdaroughly-equal10 4 ) with the International Ultraviolet Explorer (IUE). Of the seven DA white dwarfs, three show spectral signatures of ionized heavy elements, such as Si II, SI III, C IV, Si IV, and N V, arising in the immediate environment of these stars. The shortward-shifted lines in two (G191--B2B and 2111+49) of the three DA types showing metallic lines are tentatively interpreted as an indication of mass loss from these stars. The He-rich white dwarf shows the features due to C cV and He II, which also arise in the immediate environment of that star. Although the statistical sample presented here is limited, we tentatively suggest a temperature and effective gravity range (T/sub eff/> or approx. =20,000 K and log (g) < or approx. =8.0) in DA white dwarfs within which metallic lines are present either in the photosphere or in the halo of the stars. We examine the physical processes relevant to the appearance of such metallic lines. We tentatively propose that radiative levitation can explain the appearance of the observed lines in the hot DA white dwarfs, although the role of radiation forces in mass loss is not clear

Disintegration and size reduction of slags and metals after melt refining of contaminated metallic wastes

International Nuclear Information System (INIS)

Heshmatpour, B.; Copeland, G.L.; Heestand, R.L.

1981-04-01

Melting under an oxidizing slag is an attractive method of decontaminating and reducing the volume of radioactively contaminated metal scrap. The contaminants are concentrated in a relatively small volume of slag, which leaves the metal essentially clean. A potential method of permanently disposing of the resulting slags (and metals if necessary) is emplacing them into deep shale by grout hydrofracture. Suspension in grout mixtures requires that the slag and metal be granular. The feasibility of size-reducing slags and disintegrating metals and subsequently incorporating both into grout mixtures was demonstrated. Various types of slags were crushed with a small jaw crusher into particles smaller than 3 mm. Several metals were also melted and water-blasted into coarse metal powder or shot ranging in size from 0.05 to 3 mm. A simple low-pressure water atomizer having a multiple nozzle with a converging-line jet stream was developed and used for this purpose. No significant slag dust and steam were generated during slag crushing and liquid-metal water-blasting tests, indicating that contamination can be well contained within the system. The crushed slags and the coarse metal powders were suspendable in group fluids, which indicates probable disposability by shale hydrofracture. The granulation of slags and metals facilitates their containment, transport, and storage

Precious-metal-base advanced materials

International Nuclear Information System (INIS)

Nowicki, T.; Carbonnaux, C.

1993-01-01

Precious metals constitute also the base of several advanced materials used in the industry in hundreds of metric tons. Platinum alloys have been used as structural materials for equipments in the glass industry. The essential reason for this is the excellent resistance of platinum alloys to oxidation and electrolytical corrosion in molten glasses at temperatures as high as 1200-1500 C. The major drawback is a weak creep resistance. The unique way for significant improvement of platinum base materials creep resistance is a strengthening by an oxide dispersion (ODS). In the case of CLAL's patented ''Plativer'' materials, 0.05 wt% of Y 2 O 3 is incorporated within the alloy matrix by the flame spraying process. Further improvement of platinum base materials is related, in the authors opinion, to the development of precious metals base intermetallics. Another interesting applications of precious metals are silver base electrical contacts. They are in fact silver matrix composites containing varying amounts of well-dispersed particles of constituents such as CdO, SnO 2 , Ni, WC or C. In the case of such materials, particular properties are required and tested : resistance to arc erosion, resistance to welding and contact resistance. Many other technically fascinating precious metals base materials exist: brazing alloys for assembling metals, superconductors and ceramics; dental materials including magnetic biocompatible alloys; silver composites for superconductor wire jackets. The observation of current evolution indicates very clearly that precious metals cannot be replaced by common metals because of their unique characteristics due to their atomic level properties

Comparison of adaptability to heavy metals among crop plants (part 2). Adaptability to zinc group metals-studies on the comparative plant nutrition

Energy Technology Data Exchange (ETDEWEB)

Tanaka, A; Tadano, T; Muto, K

1975-01-01

Eighteen crop species were grown in culture solution having graded levels of Zn, Cd and Hg, and the differences among species in response to these elements were discussed. As the average of all species tested, the metal content of the shoot is Ca > Mn > Zn > Cd > Hg, and the root-to-shoot content ratio is reversed at equivalent levels. These values increase with an increase in the level of respective ions in the culture solution. The metal concentration in the shoot among species does not change significantly with the level of that element. There is a positive correlation among species between Zn and Cd, but Hg shows a different trend. The tolerance to Zn is weak in many species of Gramineae and Curciferae, and strong Solanaceae and Umbelliferae. Many species of Gramineae are very tolerant to high levels of Zn or Cd due to a high excluding power of the roots, but possess a weak tolerance to high Hg levels. Egg-plant, soybean, and pea are susceptible to high levels of all three elements.

Low-energy Electro-weak Reactions

International Nuclear Information System (INIS)

Gazit, Doron

2012-01-01

Chiral effective field theory (EFT) provides a systematic and controlled approach to low-energy nuclear physics. Here, we use chiral EFT to calculate low-energy weak Gamow-Teller transitions. We put special emphasis on the role of two-body (2b) weak currents within the nucleus and discuss their applications in predicting physical observables.

Oxygen and iron abundances in two metal-poor dwarfs

Science.gov (United States)

Spiesman, William J.; Wallerstein, George

1991-11-01

Oxygen abundances from the O I line at 6300 A in two metal-poor K dwarfs, HD 25329 and HD 134440, are derived. The spectra were obtained with the KPNO 4-m echelle spectrograph and long camera, yielding a resolution of 32,000 and an S/N of about 125. Model atmospheres with Te of 4770 were appropriate to both stars, whose metallicities were found to be -1.74 and -1.43 for HD 25329 and HD 134440, respectively. These oxygen abundances are 0.3 and 0.4 for the two stars. From the resolution an S/N a 3(sigma) upper limit of 0.8 is derived for each star, which may be combined into an upper limit of O/Fe of 0.6 for a generic K dwarf with Fe/H of 1.6. These values are more in line with O/Fe as seen in similarly metal-poor red giant than those reported in metal-poor subdwarfs by Abia and Rebolo (1989).

An Algorithm to Compress Line-transition Data for Radiative-transfer Calculations

Science.gov (United States)

Cubillos, Patricio E.

2017-11-01

Molecular line-transition lists are an essential ingredient for radiative-transfer calculations. With recent databases now surpassing the billion-line mark, handling them has become computationally prohibitive, due to both the required processing power and memory. Here I present a temperature-dependent algorithm to separate strong from weak line transitions, reformatting the large majority of the weaker lines into a cross-section data file, and retaining the detailed line-by-line information of the fewer strong lines. For any given molecule over the 0.3-30 μm range, this algorithm reduces the number of lines to a few million, enabling faster radiative-transfer computations without a significant loss of information. The final compression rate depends on how densely populated the spectrum is. I validate this algorithm by comparing Exomol’s HCN extinction-coefficient spectra between the complete (65 million line transitions) and compressed (7.7 million) line lists. Over the 0.6-33 μm range, the average difference between extinction-coefficient values is less than 1%. A Python/C implementation of this algorithm is open-source and available at https://github.com/pcubillos/repack. So far, this code handles the Exomol and HITRAN line-transition format.

Optical emission spectra of a copper plasma produced by a metal vapour vacuum arc plasma source

International Nuclear Information System (INIS)

Yotsombat, B.; Poolcharuansin, P.; Vilaithong, T.; Davydov, S.; Brown, I.G.

2001-01-01

Optical emission spectroscopy in the range 200-800 nm was applied for investigation of the copper plasma produced by a metal vapour vacuum arc plasma source. The experiments were conducted for the cases when the plasma was guided by straight and Ω-shaped curved solenoids as well as without solenoids, and also for different vacuum conditions. It was found that, besides singly- and doubly-charged ions, a relatively high concentration of excited neutral copper atoms was present in the plasma. The relative fraction of excited atoms was much higher in the region close to the cathode surface than in the plasma column inside the solenoid. The concentration of excited neutral, singly- and doubly-ionized atoms increased proportionally when the arc current was increased to 400 A. Some weak lines were attributed to more highly ionized copper species and impurities in the cathode material. (author)

Supramolecular assembly of group 11 phosphorescent metal complexes for chemosensors of alcohol derivatives

Science.gov (United States)

Lintang, H. O.; Ghazalli, N. F.; Yuliati, L.

2018-04-01

We report on systematic study on vapochromic sensing of ethanol by using phosphorescent trinuclear metal pyrazolate complexes with supramolecular assembly of weak intermolecular metal-metal interactions using 4-(3,5-dimethoxybenzyl)-3,5-dimethyl pyrazole ligand (1) and group 11 metal ions (Cu(I), Ag(I), Au(I)). Upon excitation at 284, the resulting complexes showed emission bands with a peak centered at 616, 473 and 612 nm for 2(Cu), 2(Ag) and 2(Au), respectively. Chemosensor 2(Cu) showed positive response to ethanol vapors in 5 mins by blue-shifting its emission band from 616 to 555 nm and emitting bright orange to green. Otherwise 2(Au) gave shifting from its emission band centered at 612 to 587 nm with Δλ of 25 nm (41%) and color changes from red-orange to light green-orange while 2(Ag) showed quenching in its original emission intensity at 473 nm in 40% with color changes from dark green to less emissive. These results demonstrate that sensing capability of chemosensor 2(Cu) with suitable molecular design of ligand and metal ion in the complex is due to the formation of a weak intermolecular hydrogen bonding interaction of O atom at the methoxy of the benzyl ring with the OH of the vapors at the outside of the molecules.

Starlight excitation of permitted lines in gaseous nebulae

International Nuclear Information System (INIS)

Grandi, S.A.

1975-01-01

The weak heavy element permitted lines observed in the spectra of gaseous nebula have, with only a few exceptions, been thought to be excited only by recombination. The accuracy of this assumption for individual lines in nebula spectra is investigated in detail via model nebula calculations. First, approximations and techniques of calculation are considered for the three possible excitation mechanisms: recombination, resonance fluorescence by the starlight continuum, and resonance fluorescence by other nebular emission lines. Next, the permitted lines of O I as observed in gaseous nebulae are discussed. Thirdly, it is shown that varying combinations of recombination, resonance fluorescence by starlight, and resonance fluorescence by other nebula lines can successfully account for the observed strengths in the Orion Nebula of lines of the following ions: C II, N I, N II, N III, O II, Ne II, Si II, Si III, and S III. A similar analysis is performed for the lines in the spectra of the planetary nebulae NGC7662 and NGC7027, and, with some exceptions, satisfactory agreement between the observed and predicted line strengths is found. Finally, observations of the far red spectra of the Orion Nebula, the planetary nebulae NGC3242, NGC6210, NGC2392, IC3568, IC4997, NGC7027, and MGC7662, and the reflection nebulae IC431 and NGC2068 are reported

Instrumental systematics and weak gravitational lensing

International Nuclear Information System (INIS)

Mandelbaum, R.

2015-01-01

We present a pedagogical review of the weak gravitational lensing measurement process and its connection to major scientific questions such as dark matter and dark energy. Then we describe common ways of parametrizing systematic errors and understanding how they affect weak lensing measurements. Finally, we discuss several instrumental systematics and how they fit into this context, and conclude with some future perspective on how progress can be made in understanding the impact of instrumental systematics on weak lensing measurements

Robust weak measurements on finite samples

International Nuclear Information System (INIS)

Tollaksen, Jeff

2007-01-01

A new weak measurement procedure is introduced for finite samples which yields accurate weak values that are outside the range of eigenvalues and which do not require an exponentially rare ensemble. This procedure provides a unique advantage in the amplification of small nonrandom signals by minimizing uncertainties in determining the weak value and by minimizing sample size. This procedure can also extend the strength of the coupling between the system and measuring device to a new regime

On weakly D-differentiable operators

DEFF Research Database (Denmark)

Christensen, Erik

2016-01-01

Let DD be a self-adjoint operator on a Hilbert space HH and aa a bounded operator on HH. We say that aa is weakly DD-differentiable, if for any pair of vectors ξ,ηξ,η from HH the function 〈eitDae−itDξ,η〉〈eitDae−itDξ,η〉 is differentiable. We give an elementary example of a bounded operator aa......, such that aa is weakly DD-differentiable, but the function eitDae−itDeitDae−itD is not uniformly differentiable. We show that weak  DD-differentiability   may be characterized by several other properties, some of which are related to the commutator (Da−aD)...

CHEMICAL EVOLUTION OF THE UNIVERSE AT 0.7 < z < 1.6 DERIVED FROM ABUNDANCE DIAGNOSTICS OF THE BROAD-LINE REGION OF QUASARS

Energy Technology Data Exchange (ETDEWEB)

Sameshima, H. [Laboratory of Infrared High-resolution Spectroscopy, Koyama Astronomical Observatory, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan); Yoshii, Y.; Kawara, K., E-mail: sameshima@cc.kyoto-su.ac.jp [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

2017-01-10

We present an analysis of Mg ii λ 2798 and Fe ii UV emission lines for archival Sloan Digital Sky Survey (SDSS) quasars to explore the diagnostics of the magnesium-to-iron abundance ratio in a broad-line region cloud. Our sample consists of 17,432 quasars selected from the SDSS Data Release 7 with a redshift range of 0.72 <  z  < 1.63. A strong anticorrelation between the Mg ii equivalent width (EW) and the Eddington ratio is found, while only a weak positive correlation is found between the Fe ii EW and the Eddington ratio. To investigate the origin of these differing behaviors of Mg ii and Fe ii emission lines, we perform photoionization calculations using the Cloudy code, where constraints from recent reverberation mapping studies are considered. We find from calculations that (1) Mg ii and Fe ii emission lines are created at different regions in a photoionized cloud, and (2) their EW correlations with the Eddington ratio can be explained by just changing the cloud gas density. These results indicate that the Mg ii/Fe ii flux ratio, which has been used as a first-order proxy for the Mg/Fe abundance ratio in chemical evolution studies with quasar emission lines, depends largely on the cloud gas density. By correcting this density dependence, we propose new diagnostics of the Mg/Fe abundance ratio for a broad-line region cloud. In comparing the derived Mg/Fe abundance ratios with chemical evolution models, we suggest that α -enrichment by mass loss from metal-poor intermediate-mass stars occurred at z  ∼ 2 or earlier.

Weakly distributive modules. Applications to supplement submodules

Indian Academy of Sciences (India)

Abstract. In this paper, we define and study weakly distributive modules as a proper generalization of distributive modules. We prove that, weakly distributive supplemented modules are amply supplemented. In a weakly distributive supplemented module every submodule has a unique coclosure. This generalizes a result of ...

Dynamics of oil price, precious metal prices, and exchange rate

International Nuclear Information System (INIS)

Sari, Ramazan; Soytas, Ugur; Hammoudeh, Shawkat

2010-01-01

This study examines the co-movements and information transmission among the spot prices of four precious metals (gold, silver, platinum, and palladium), oil price, and the US dollar/euro exchange rate. We find evidence of a weak long-run equilibrium relationship but strong feedbacks in the short run. The spot precious metal markets respond significantly (but temporarily) to a shock in any of the prices of the other metal prices and the exchange rate. Furthermore, we discover some evidence of market overreactions in the palladium and platinum cases as well as in the exchange rate market. In conclusion, whether there are overreactions and re-adjustments or not, investors may diversify at least a portion of the risk away by investing in precious metals, oil, and the euro. Policy implications are provided. (author)

Fermi level dependent native defect formation: Consequences for metal-semiconductor and semiconductor-semiconductor interfaces

International Nuclear Information System (INIS)

Walukiewicz, W.

1988-02-01

The amphoteric native defect model of the Schottky barrier formation is used to analyze the Fermi level pinning at metal/semiconductor interfaces for submonolayer metal coverages. It is assumed that the energy required for defect generation is released in the process of surface back-relaxation. Model calculations for metal/GaAs interfaces show a weak dependence of the Fermi level pinning on the thickness of metal deposited at room temperature. This weak dependence indicates a strong dependence of the defect formation energy on the Fermi level, a unique feature of amphoteric native defects. This result is in very good agreement with experimental data. It is shown that a very distinct asymmetry in the Fermi level pinning on p- and n-type GaAs observed at liquid nitrogen temperatures can be understood in terms of much different recombination rates for amphoteric native defects in those two types of materials. Also, it is demonstrated that the Fermi level stabilization energy, a central concept of the amphoteric defect system, plays a fundamental role in other phenomena in semiconductors such as semiconductor/semiconductor heterointerface intermixing and saturation of free carrier concentration. 33 refs., 6 figs

Skills Associated with Line Breaks in Elite Rugby Union

Directory of Open Access Journals (Sweden)

Steve den Hollander, James Brown, Michael Lambert, Paul Treu, Sharief Hendricks

2016-09-01

Full Text Available The ability of the attacking team to break through the defensive line is a key indicator of success as it creates opportunities to score tries. The aim of this study was to analyse line breaks and identify the associated skills and playing characteristics. The 2013 Super Rugby season (125 games was analysed, in which 362 line breaks were identified and coded using variables that assessed team patterns and non-contact attacking skills in the phases preceding the line break. There was an average of 3 line breaks per game, with 39% of line breaks resulting in a try. Line breaks occurred when the ball-carrier was running fast [61%, x2(4 = 25.784, p = 0.000, Cramer’s v = 0.1922, weak]. At a moderate distance, short lateral passes (19% and skip passes (15% attributed to the highest percentage of line breaks [x2(26 = 50.899, p = 0.036, Cramer’s v = 0.2484, moderate]. Faster defensive line speeds resulted in more line breaks [x2(12 = 61.703, p < 0.001, Cramer’s v = 0.3026, moderate]. Line breaks are associated with overall team success and try scoring opportunities. Awareness of the defenders line speed and depth, fast running speed when receiving the ball and quick passing between attackers to the outside backs creates line break opportunities. During training, coaches should emphasise the movement speed of the ball between attackers and manipulate the speed and distance of the defenders.

Geometric phase topology in weak measurement

Science.gov (United States)

Samlan, C. T.; Viswanathan, Nirmal K.

2017-12-01

The geometric phase visualization proposed by Bhandari (R Bhandari 1997 Phys. Rep. 281 1-64) in the ellipticity-ellipse orientation basis of the polarization ellipse of light is implemented to understand the geometric aspects of weak measurement. The weak interaction of a pre-selected state, acheived via spin-Hall effect of light (SHEL), results in a spread in the polarization ellipticity (η) or ellipse orientation (χ) depending on the resulting spatial or angular shift, respectively. The post-selection leads to the projection of the η spread in the complementary χ basis results in the appearance of a geometric phase with helical phase topology in the η - χ parameter space. By representing the weak measurement on the Poincaré sphere and using Jones calculus, the complex weak value and the geometric phase topology are obtained. This deeper understanding of the weak measurement process enabled us to explore the techniques’ capabilities maximally, as demonstrated via SHEL in two examples—external reflection at glass-air interface and transmission through a tilted half-wave plate.

Lined rock caverns for the storage of hazardous waste

International Nuclear Information System (INIS)

Semprich, S.; Speidel, S.R.; Schneider, H.J.

1987-01-01

For reasons of environmental protection the storage of hazardous waste in unlined rock caverns is possible to a very limited extent only. Therefore, the authors have recently developed technologies for the lining and sealing of rock caverns. In the process, sealing systems of synthetic materials or metals have proved suitable. Synthetic materials can be used in the form of either sheets or coatings with various materials such as epoxy resins, polyethylenes etc. being used. Metal sealings consist of thin sheets or foils which are either welded or bonded. In either case, the structural design must provide for a leakage control possibility. The article describes the design principles, the structural and operational aspects as well as the control measures with regard to the planning and execution of lined rock caverns for the storage of hazardous waste

Diagnostics of metal state in steam lines

International Nuclear Information System (INIS)

Gofman, Yu.M.; Kazantseva, N.S.; Losev, L.Ya.; Nevolina, G.S.

1986-01-01

A series of micropore detection methods is suggested: light microscopy, electron microscopy, hydrostatic weighing; and comparative investigations of pore-formation processes in 12Kh1MF steel steam lines, which have operated for about 100 thousand hours at t=550 deg C and 47-55 MPa stresses are conducted using these methods. It is shown, that electron microscpy method can be applied at the early stages damaging, when embrionic micropores of 0.1 μm in size appear. Optical metallography allows one to detect pores of about 1 μm in size. Damage in density using the hydrostatic weighing method is estimated in the following way: at creep stages 1-2-0.1; at stage 3-0.4-0.6; at predestruction stage the degree of damage equals to 0.7-0.8

Basic deuteroexchange in transition metal complexes with nitrogen-containing aromatic heterocycles

International Nuclear Information System (INIS)

Tupitsyn, I.F.

1986-01-01

Kinetics of deuteroexchange in the methyl group of nitrate complexes of a metal - nickel (2) - with different methyl-substituted aromatic heterocycles and isostructural complexes of a ligand - 2 - methyl quinoline - with different central metal atoms (Mn(2), Ni(2), Cu(2), Zn(2)) is studied. Series for influence of ligand structure on deuteroexchange rate in complexes doesn't correspond qualitatively to series for deuteroexchange rate increase in noncoordinated ligands. Deuteroexchange rate is weakly subjected to influence of exchange in metal-complexing agent. Deuteroexchange mechanism is suggested and discussed. According to this mechanism the structure developed in the course of the exchange process with electron density transfer from the heterocyclic ligand to a metal ion is a transition state of the reaction

Weak radiative hyperon decays

International Nuclear Information System (INIS)

Roberts, B.L.; Booth, E.C.; Gall, K.P.; McIntyre, E.K.; Miller, J.P.; Whitehouse, D.A.; Bassalleck, B.; Hall, J.R.; Larson, K.D.; Wolfe, D.M.; Fickinger, W.J.; Robinson, D.K.; Hallin, A.L.; Hasinoff, M.D.; Measday, D.F.; Noble, A.J.; Waltham, C.E.; Hessey, N.P.; Lowe, J.; Horvath, D.; Salomon, M.

1990-01-01

New measurements of the Σ + and Λ weak radiative decays are discussed. The hyperons were produced at rest by the reaction K - p → Yπ where Y = Σ + or Λ. The monoenergetic pion was used to tag the hyperon production, and the branching ratios were determined from the relative amplitudes of Σ + → pγ to Σ + → pπ 0 and Λ → nγ to Λ → nπ 0 . The photons from weak radiative decays and from π 0 decays were detected with modular NaI arrays. (orig.)

Weak strange particle production: advantages and difficulties

International Nuclear Information System (INIS)

Angelescu, Tatiana; Baker, O.K.

2002-01-01

Electromagnetic strange particle production developed at Jefferson Laboratory was an important source of information on strange particle electromagnetic formfactors and induced and transferred polarization. The high quality of the beam and the detection techniques involved could be an argument for detecting strange particles in weak interactions and answer questions about cross sections, weak formfactors, neutrino properties, which have not been investigated yet. The paper analyses some aspects related to the weak lambda production and detection with the Hall C facilities at Jefferson Laboratory and the limitations in measuring the weak interaction quantities. (authors)

Detection of low-metallicity warm plasma in a galaxy overdensity environment at z ˜ 0.2

Science.gov (United States)

Narayanan, Anand; Savage, Blair D.; Mishra, Preetish K.; Wakker, Bart P.; Khaire, Vikram; Wadadekar, Yogesh

2018-04-01

We present results from the analysis of a multiphase O VI-broad Ly α (BLA) absorber at z = 0.19236 in the HubbleSpaceTelescope/Cosmic Origins Spectrograph spectrum of PG 1121 + 422. The low and intermediate ionization metal lines in this absorber have a single narrow component, whereas the Ly α has a possible broad component with b({H {I}}) ˜ 71 km s-1. Ionization models favour the low and intermediate ions coming from a T ˜ 8500 K, moderately dense (n H ˜ 10 - 3 cm-3) photoionized gas with near solar metallicities. The weak O VI requires a separate gas phase that is collisionally ionized. The O VI coupled with BLA suggests T ˜ 3.2 × 105 K, with significantly lower metal abundance and ˜1.8 orders of magnitude higher total hydrogen column density compared to the photoionized phase. Sloan Digitial Sky Survey (SDSS) shows 12 luminous (>L*) galaxies in the ρ ≤ 5 Mpc, |Δv| ≤ 800 km s-1 region surrounding the absorber, with the absorber outside the virial bounds of the nearest galaxy. The warm phase of this absorber is consistent with being transition temperature plasma either at the interface regions between the hot intragroup gas and cooler photoionized clouds within the group, or associated with high velocity gas in the halo of a ≲L* galaxy. The absorber highlights the advantage of O VI-BLA absorbers as ionization model independent probes of warm baryon reserves.

Identification of Metal Absorption Lines on Quasar Spectra of SDSS ...

Indian Academy of Sciences (India)

. Baise 533000, China. 2Guangdong University of Technology, Guangzhou 510006, China. 3Centre for Astrophysics, Guangzhou University, Guangzhou 510006, China. ∗ e-mail: cysu@gdut.edu.cn. Abstract. Absorption lines are an important ...

Mesospheric temperature estimation from meteor decay times of weak and strong meteor trails

Science.gov (United States)

Kim, Jeong-Han; Kim, Yong Ha; Jee, Geonhwa; Lee, Changsup

2012-11-01

Neutral temperatures near the mesopause region were estimated from the decay times of the meteor echoes observed by a VHF meteor radar during a period covering 2007 to 2009 at King Sejong Station (62.22°S, 58.78°W), Antarctica. While some previous studies have used all meteor echoes to determine the slope from a height profile of log inverse decay times for temperature estimation, we have divided meteor echoes into weak and strong groups of underdense meteor trails, depending on the strength of estimated relative electron line densities within meteor trails. We found that the slopes from the strong group are inappropriate for temperature estimation because the decay times of strong meteors are considerably scattered, whereas the slopes from the weak group clearly define the variation of decay times with height. We thus utilize the slopes only from the weak group in the altitude region between 86 km and 96 km to estimate mesospheric temperatures. The meteor estimated temperatures show a typical seasonal variation near the mesopause region and the monthly mean temperatures are in good agreement with SABER temperatures within a mean difference of 4.8 K throughout the year. The meteor temperatures, representing typically the region around the altitude of 91 km, are lower on average by 2.1 K than simultaneously measured SATI OH(6-2) rotational temperatures during winter (March-October).

Study of weak interaction with p-p colliding beam

International Nuclear Information System (INIS)

Arafune, Jiro; Sugawara, Hirotaka

1975-01-01

Weak interaction in the energy range of TRISTAN project is discussed. The cross-section of production of weak boson in p-p reaction was calculated with the parton model. The observation of weak boson may be possible. The production rate of neutral weak boson was also estimated on the basis of the Weinberg model, and was almost same as that of weak boson. The method of observation of weak boson is suggested. The direct method is the observation of lepton pair due to the decay of neutral weak boson. It is expected that the spectrum of decay products (+ -) in the decay of weak boson shows a characteristic feature, and it shows the existence of weak boson. Weak interaction makes larger contribution in case of large momentum transfer than electromagnetic interaction. When the momentum transfer is larger than 60 GeV/c, the contribution of weak interaction is dominant over the others. Therefore, the experiments at high energy will give informations concerning the relations among the interactions of elementary particles. Possibility of study on the Higgs scalar meson is also discussed. (Kato, T.)

Chemical composition and effective temperatures of metallic line white dwarfs

International Nuclear Information System (INIS)

Hammond, G.L.

1974-01-01

Model atmosphere techniques have been employed to determine the composition, effective temperatures, radii, masses and surface gravities of white dwarfs Ross 640 and van Maanen 2. The non-gray, LTE, convective, constant flux models employed collisional damping constants for the Ca II H and K lines that were measured in a laboratory device that simulated white dwarf atmospheric conditions. Ross 640 was found to have an extremely helium-rich composition and T/sub eff/ = 8500K, while the observed properties of van Maanen 2 were fitted best by a model with 91 percent helium, 9 percent hydrogen and T/sub eff/ = 6100K. The laboratory measurements of pressure shifts for the Ca II lines casts some doubt on the interpretation of recent radial velocity determinations for van Maanen 2. (U.S.)

Measurement of heavy metals by means of a plasma-assisted method

International Nuclear Information System (INIS)

Hernberg, R.; Haeyrinen, V.; Oikari, R.

1995-01-01

The plasma-assisted measuring device for on-line measurement of alkali metal concentrations in pressurised processes, which has been developed in the Laboratory, will be further developed to provide for simultaneous measurement of heavy metal concentrations. (author)

Synthesis of Chromonylthiazolidines and Their Cytotoxicity to Human Cancer Cell Lines

Directory of Open Access Journals (Sweden)

Hoang Le Tuan Anh

2015-01-01

Full Text Available Nine new chromonylthiazolidine derivatives were successfully semi-synthesized from paeonol. All of the compounds, including starting materials, the intermediate compound and products, were evaluated for their cytotoxic effects toward eight human cancer cell lines. The synthesized chromonylthiazolidines displayed weak cytotoxic effects against the tested cancer cell lines, but selective cytotoxic effects were observed. Compounds 3a and 3b showed the most selective cytotoxic effects against human epidermoid carcinoma (IC50 44.1 ± 3.6 μg/mL and breast cancer (IC50 32.8 ± 1.4 μg/mL cell lines, respectively. The results suggest that chromoylthiazolidines are potential low-cost, and selective anticancer agents.

Ideal Coulomb Plasma Approximation in Line Shape Models: Problematic Issues

Directory of Open Access Journals (Sweden)

Joel Rosato

2014-06-01

Full Text Available In weakly coupled plasmas, it is common to describe the microfield using a Debye model. We examine here an “artificial” ideal one-component plasma with an infinite Debye length, which has been used for the test of line shape codes. We show that the infinite Debye length assumption can lead to a misinterpretation of numerical simulations results, in particular regarding the convergence of calculations. Our discussion is done within an analytical collision operator model developed for hydrogen line shapes in near-impact regimes. When properly employed, this model can serve as a reference for testing the convergence of simulations.

Compartmentation and complexation of metals in hyperaccumulator plants

Directory of Open Access Journals (Sweden)

Barbara eLeitenmaier

2013-09-01

Full Text Available Hyperaccumulators are being intensely investigated. They are not only interesting in scientific context due to their strange behaviour in terms of dealing with high concentrations of metals, but also because of their use in phytoremediation and phytomining, for which understanding the mechanisms of hyperaccumulation is crucial. Hyperaccumulators naturally use metal accumulation as a defence against herbivores and pathogens, and therefore deal with accumulated metals in very specific ways of complexation and compartmentation, different from non-hyperaccumulator plants and also non-hyperaccumulated metals. For example, in contrast to non-hyperaccumulators, in hyperaccumulators even the classical phytochelatin-inducing metal, cadmium, is predominantly not bound by such sulfur ligands, but only by weak oxygen ligands. This applies to all hyperaccumulated metals investigated so far, as well as hyperaccumulation of the metalloid arsenic. Stronger ligands, as they have been shown to complex metals in non-hyperaccumulators, are in hyperaccumulators used for transient binding during transport to the storage sites. This confirmed that enhanced active metal transport, and not metal complexation, is the key mechanism of hyperaccumulation. Hyperaccumulators tolerate the high amount of accumulated heavy metals by sequestering them into vacuoles, usually in large storage cells of the epidermis. This is mediated by strongly elevated expression of specific transport proteins in various tissues from metal uptake in the shoots up to the storage sites in the leaf epidermis. However, this mechanism seems to be very metal specific. Non-hyperaccumulated metals in hyperaccumulators seem to be dealt with like in non-hyperaccumulator plants, i.e. detoxified by binding to strong ligands such as metallothioneins.

Sensing of polymeric sensor-based rhodamine B derivative for metal ...

Indian Academy of Sciences (India)

The development of fluorescent sensors for the detection of environmentally ... mechanical and thermal stability, weak chemical union with the metals ..... signals corresponding to the vinyl groups of the monomer. (d(H) 5.77 .... Photographs recorded under (a) visible light and (b) UV light at 365 nm for aqueous solutions of ...

Boiling points of halogenated ethanes: an explanatory model implicating weak intermolecular hydrogen-halogen bonding.

Science.gov (United States)

Beauchamp, Guy

2008-10-23

This study explores via structural clues the influence of weak intermolecular hydrogen-halogen bonds on the boiling point of halogenated ethanes. The plot of boiling points of 86 halogenated ethanes versus the molar refraction (linked to polarizability) reveals a series of straight lines, each corresponding to one of nine possible arrangements of hydrogen and halogen atoms on the two-carbon skeleton. A multiple linear regression model of the boiling points could be designed based on molar refraction and subgroup structure as independent variables (R(2) = 0.995, standard error of boiling point 4.2 degrees C). The model is discussed in view of the fact that molar refraction can account for approximately 83.0% of the observed variation in boiling point, while 16.5% could be ascribed to weak C-X...H-C intermolecular interactions. The difference in the observed boiling point of molecules having similar molar refraction values but differing in hydrogen-halogen intermolecular bonds can reach as much as 90 degrees C.

Nonleptonic decays of 1/2+-baryons and pseudo-connected-line diagrams, 1

International Nuclear Information System (INIS)

Abe, Yoshikazu; Fujii, Kanji

1978-01-01

Under the SU(4)-20''-spurion dominance in nonleptonic weak decays, we investigate algebraic structures of the effective Hamiltonian H sub(eff) which describes the main features of the nonleptonic weak decays of ordinary baryons. When H sub(eff) is written by using 20'-baryon (1/2 + ) wave function of the form B sub(α)sup([βγ]), one can select out of H sub(eff) two terms which describe most simply the main features of the P-wave amplitudes for ordinary baryons. Only these terms are s-u dual in the sense of 'pseudo-connected-line diagrams' (pseudo-CLD's) obtained by writing CLD's with 4- and 4*-lines corresponding directly to the lower and the upper indices of B sub(α)sup([βγ]). By assuming Lee-Sugawara relation and s-u dual property of the P-wave amplitudes, various relations among ordinary and charmed baryon decays are derived. Comments on the parity-violating amplitudes are also given. (auth.)

Depths of formation of the CN molecule lines in the solar atmosphere

International Nuclear Information System (INIS)

Porfir'eva, G.A.

1975-01-01

The depths of production of lines of weak bands of the CN molecule violet (lambda=4216A) system are calculated by the weight function method. Two models of solar atmosphere are used. Lines with the different rotational vibrational quantum numbers are produced practically in the same layer (tau approximately equal to 0.05-0.06). The difference of depths of production of the line center and the wing is small (Δtau 0 =0.005). The contribution functions for the solar disk center differ little from those for the edge. The calculations carried out are in good agreement with the results obtained from earlier observations

Residential Distance to High-voltage Power Lines and Risk of Neurodegenerative Diseases

DEFF Research Database (Denmark)

Frei, Patrizia; Poulsen, Aslak Harbo; Mezei, Gabor

2013-01-01

period 5-20 years before diagnosis were computed. The risks for developing dementia, Parkinson's disease, multiple sclerosis, and motor neuron disease were not increased in persons living within close vicinity of a power line. The risk of Alzheimer's disease was not increased for ever living within 50 m...... of a power line (hazard ratio = 1.04, 95% confidence interval: 0.69, 1.56). No dose-response according to number of years of living within 50 m of a power line was observed, but there were weak indications of an increased risk for persons diagnosed by the age of 75 years. Overall, there was little support...

Study of the nanostructure of Gum Metal using energy-filtered transmission electron microscopy

International Nuclear Information System (INIS)

Yano, T.; Murakami, Y.; Shindo, D.; Kuramoto, S.

2009-01-01

The nanostructure of Gum Metal, which has many anomalous mechanical properties, was investigated using transmission electron microscopy with energy filtering. A precise analysis of the weak diffuse electron scattering that was observed in the electron diffraction patterns of the Gum Metal specimen revealed that Gum Metal contains a substantial amount of the nanometer-sized ω phase. The morphology of the ω phase appeared to have a correlation with the faulting in the {2 1 1} planes, which are one of the characteristic lattice imperfections of the Gum Metal specimen. It is likely that the nanometer-sized ω phase may be a type of obstacle related to the restriction of the dislocation movement, which has been a significant problem in research on Gum Metal

Off-line programming (OLP) system comparison

International Nuclear Information System (INIS)

Holliday, M.A.

1993-01-01

Off-line programming (OLP) systems are being used to conceptualize, design, simulate, and now control automated robotic workcells. Currently available systems by Deneb, SILMA, and Cimetrix are being used at the Lawrenece Livermore National Laboratory (LLNL) to simulate and control automated robotic systems for radioactive material processing and hazardous waste sorting. The differences in system architectures, workcell and robot calibration procedures, operator interface, and graphical output capability of each will be discussed. The relative strengths and weaknesses of these attributes will be discussed as they relate to varying applications in robotic workcell development and control

Start up testing for the secure automated fabrication line

International Nuclear Information System (INIS)

Gerber, E.W.; Benson, E.M.; Dahl, R.E.

1987-01-01

The secure automated fabrication (SAF) line is a remotely operated, liquid metal reactor fuel fabrication process being built by Westinghouse Hanford Company for the Department of Energy. All process and control equipment is installed and start up testing has been initiated. Start up testing is comprised of five phases, each incorporating higher degrees of equipment integration, automation, and remote control. Testing methodology for SAF line start up is described in this report

Pressure brazing of ceramics to metals with copper solder

International Nuclear Information System (INIS)

Pavlova, M.A.; Metelkin, I.I.

1986-01-01

The effect on the quality of joints brazed with copper of different non metallized aluminooxide dielectrics with metals and alloys of a series of technological parameters (temperature, pressure, holding, and medium) in the course of pressure brazing is investigated. It is shown that in case of brazing with kovar and nickel the character of dependences is identical, however in all cases the joints with nickel are more durable. For the ceramics - molybdenum system characterized by weak interaction with copper solder kinetic dependences have no maximum and only under holding of more than 20 min the constant strength of 150-190 MPa is attained

Superconducting proximity effect in mesoscopic superconductor/normal-metal junctions

CERN Document Server

Takayanagi, H; Toyoda, E

1999-01-01

The superconducting proximity effect is discussed in mesoscopic superconductor/normal-metal junctions. The newly-developed theory shows long-range phase-coherent effect which explaines early experimental results of giant magnetoresistance oscillations in an Andreev interferometer. The theory also shows that the proximity correction to the conductance (PCC) has a reentrant behavior as a function of energy. The reentrant behavior is systematically studied in a gated superconductor-semiconductor junction. A negative PCC is observed in the case of a weak coupling between the normal metal and the external reservoir. Phase coherent ac effect is also observed when rf is irradiated to the junction.

Phytoremediation of metals contaminated dredged sediments: Use of synthetic chelates in metals phytoextraction

Science.gov (United States)

Sahut, C.; Geniaut, G.; Lillo, M. P.

2003-05-01

(in Times 10 points) The waterways maintenance leads to a large volume of dredged polluted sediments, to be disposed of, every year. As the economic disposal of dredged sediment is a single line along the stream they can behave as a sink of pollutant and a migration in the environment is observed. Chelate-enhanced phytoremediation has been proposed as an effective tool for the extraction of heavy metals from dredged sediment by plants. Lysimeters studies were conducted to study the phytoremediation of sediments with EDTA and lactic acid used as synthetic chelators. EDTA appeared to enhance metal solubility by plant uptake did not increase accordingly. Futhermore EDTA enhance metal leaching which could lead 10 groungwater pollution. To prevent these unwanted side-effects, careful management of phytoremediation and of the use of EDTA seems necessary.

Nuclear magnetic resonance line-shape analysis and determination of exchange rates

International Nuclear Information System (INIS)

Rao, B.D.

1989-01-01

The fact that chemical exchange processes occur at rates that cover a broad range and produce readily detectable effects on the spectrum is one of the attractive features of high-resolution NMR. The description of these line shapes in the presence of spin-spin coupling requires the density matrix theory which is rather complex. Analysis of the line shapes usually needs computer simulations and is capable of providing reliable information on the exchange rates as well as spectral parameters in the absence of exchange. Simplified procedures, ignoring spin-spin coupling, often result in deviations in these exchange and spectral parameters determined. A step-by-step procedure is detailed in this chapter for setting up the matrices required for computing the line shapes of exchanges involving weakly coupled spin systems on the basis of the density matrix theory without the need for a detailed understanding of the theory. A knowledge of the energy level structure and allowed transitions in the NMR spectra of the individual weakly coupled spin systems is all that is required. The procedure is amenable to numerical computation. The group of illustrative examples chosen to demonstrate the development of the computational tools cover some of the commonly encountered cases of exchange from simple systems to rather complex ones. Such exchanges occur frequently in biological molecules, especially those involving enzyme-substrate complexes. In cases where the experimental line shapes are obtained with respectable precision, and the relevant exchange processes are unambiguously identifiable, the computer simulation method of line-shape analysis is capable of providing useful and incisive information. The example of the 31P exchanges in the adenylate kinase is illustrative of this point

Turbulent convection in liquid metal with and without rotation.

Science.gov (United States)

King, Eric M; Aurnou, Jonathan M

2013-04-23

The magnetic fields of Earth and other planets are generated by turbulent, rotating convection in liquid metal. Liquid metals are peculiar in that they diffuse heat more readily than momentum, quantified by their small Prandtl numbers, Pr rotating Rayleigh-Bénard convection experiments in the liquid metal gallium (Pr = 0.025) over a range of nondimensional buoyancy forcing (Ra) and rotation periods (E). Our primary diagnostic is the efficiency of convective heat transfer (Nu). In general, we find that the convective behavior of liquid metal differs substantially from that of moderate Pr fluids, such as water. In particular, a transition between rotationally constrained and weakly rotating turbulent states is identified, and this transition differs substantially from that observed in moderate Pr fluids. This difference, we hypothesize, may explain the different classes of magnetic fields observed on the Gas and Ice Giant planets, whose dynamo regions consist of Pr 1 fluids, respectively.

Weak convergence and uniform normalization in infinitary rewriting

DEFF Research Database (Denmark)

Simonsen, Jakob Grue

2010-01-01

the starkly surprising result that for any orthogonal system with finitely many rules, the system is weakly normalizing under weak convergence if{f} it is strongly normalizing under weak convergence if{f} it is weakly normalizing under strong convergence if{f} it is strongly normalizing under strong...... convergence. As further corollaries, we derive a number of new results for weakly convergent rewriting: Systems with finitely many rules enjoy unique normal forms, and acyclic orthogonal systems are confluent. Our results suggest that it may be possible to recover some of the positive results for strongly...

Bioaccessibility of micron-sized powder particles of molybdenum metal, iron metal, molybdenum oxides and ferromolybdenum--Importance of surface oxides.

Science.gov (United States)

Mörsdorf, Alexander; Odnevall Wallinder, Inger; Hedberg, Yolanda

2015-08-01

The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, that are manufactured, imported or used in different products (substances or articles) are identified and proven safe for humans and the environment. Metals and alloys need hence to be investigated on their extent of released metals (bioaccessibility) in biologically relevant environments. Read-across from available studies may be used for similar materials. This study investigates the release of molybdenum and iron from powder particles of molybdenum metal (Mo), a ferromolybdenum alloy (FeMo), an iron metal powder (Fe), MoO2, and MoO3 in different synthetic body fluids of pH ranging from 1.5 to 7.4 and of different composition. Spectroscopic tools and cyclic voltammetry have been employed to characterize surface oxides, microscopy, light scattering and nitrogen absorption for particle characterization, and atomic absorption spectroscopy to quantify released amounts of metals. The release of molybdenum from the Mo powder generally increased with pH and was influenced by the fluid composition. The mixed iron and molybdenum surface oxide of the FeMo powder acted as a barrier both at acidic and weakly alkaline conditions. These findings underline the importance of the surface oxide characteristics for the bioaccessibility of metal alloys. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Cobalt allergy in hard metal workers

Energy Technology Data Exchange (ETDEWEB)

Fischer, T; Rystedt, I

1983-03-01

Hard metal contains about 10% cobalt. 853 hard metal workers were examined and patch tested with substances from their environment. Initial patch tests with 1% cobalt chloride showed 62 positive reactions. By means of secondary serial dilution tests, allergic reactions to cobalt were reproduced in 9 men and 30 women. Weak reactions could not normally be reproduced. A history of hand eczema was found in 36 of the 39 individuals with reproducible positive test reactions to cobalt, while 21 of 23 with a positive initial patch test but negative serial dilution test had never had any skin problems. Hand etching and hand grinding, mainly female activities and traumatic to the hands, were found to involve the greatest risk of cobalt sensitization. 24 individuals had an isolated cobalt allergy. They had probably been sensitized by hard metal work, while the individuals, all women, who had simultaneous nickel allergy had probably been sensitized to nickel before their employment and then became sensitized to cobalt by hard metal work. A traumatic occupation, which causes irritant contact dermatitis and/or a previous contact allergy or atopy is probably a prerequisite for the development of cobalt allergy.

Changes in cytoskeletal dynamics and nonlinear rheology with metastatic ability in cancer cell lines

International Nuclear Information System (INIS)

Coughlin, Mark F; Fredberg, Jeffrey J

2013-01-01

Metastatic outcome is impacted by the biophysical state of the primary tumor cell. To determine if changes in cancer cell biophysical properties facilitate metastasis, we quantified cytoskeletal biophysics in well-characterized human skin, bladder, prostate and kidney cell line pairs that differ in metastatic ability. Using magnetic twisting cytometry with optical detection, cytoskeletal dynamics was observed through spontaneous motion of surface bound marker beads and nonlinear rheology was characterized through large amplitude forced oscillations of probe beads. Measurements of cytoskeletal dynamics and nonlinear rheology differed between strongly and weakly metastatic cells. However, no set of biophysical parameters changed systematically with metastatic ability across all cell lines. Compared to their weakly metastatic counterparts, the strongly metastatic kidney cancer cells exhibited both increased cytoskeletal dynamics and stiffness at large deformation which are thought to facilitate the process of vascular invasion. (paper)

HIDE-AND-SEEK WITH THE FUNDAMENTAL METALLICITY RELATION

Energy Technology Data Exchange (ETDEWEB)

Kashino, D. [Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602 (Japan); Renzini, A. [INAF Osservatorio Astronomico di Padova, vicolo dell’Osservatorio 5, I-35122 Padova (Italy); Silverman, J. D. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, the University of Tokyo, Kashiwanoha, Kashiwa, 277-8583 (Japan); Daddi, E., E-mail: daichi@nagoya-u.jp [Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Université Paris Diderot, Irfu/CEA-Saclay, Service d’Astrophysique, F-91191 Gif-sur-Yvette (France)

2016-06-01

We use ∼83,000 star-forming galaxies at 0.04 < z < 0.3 from the Sloan Digital Sky Survey to study the so-called fundamental metallicity relation (FMR) and report on the disappearance of its anti-correlation between metallicity and star formation rate (SFR) when using the new metallicity indicator recently proposed by Dopita et al. In this calibration, metallicity is primarily sensitive to the emission line ratio [N ii] λ 6584/[S ii] λλ 6717, 6731 that is insensitive to dilution by pristine infalling gas that may drive the FMR anti-correlation with SFR. Therefore, we conclude that the apparent disappearance of the FMR (using this new metallicity indicator) does not rule out its existence.

Confinement and Isotropization of Galactic Cosmic Rays by Molecular-Cloud Magnetic Mirrors When Turbulent Scattering Is Weak