Science.gov

Sample records for steep spectrum sources

  1. Steep Spectrum Radio Sources in Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Clarke, Tracy E.

    2012-05-01

    Steep spectrum radio emission associated with galaxy clusters comes from compact central active galactic nuclei (AGN) driven radio sources in dense cool core clusters as well as from large regions of diffuse (halo and relic) emission associated with dynamically complex merging systems. These radio halos and relics are best traced at low radio frequencies where details of their morphology, location and spectral index distribution can be used to probe the underlying acceleration mechanism(s) as well as important details of large scale structure formation. Low frequency radio observations also play an important role in the study of AGN feedback into the intracluster medium and the regulation of cooling cores. While spectacular results are coming from the current generation of low frequency instruments, there will soon be a new revolution in studies of steep spectrum sources with the upcoming generation of low frequency interferometers on Earth and ultimately the moon.

  2. IONIZED OUTFLOWS FROM COMPACT STEEP SPECTRUM SOURCES

    SciTech Connect

    Shih, Hsin-Yi; Stockton, Alan; Kewley, Lisa E-mail: stockton@ifa.hawaii.edu

    2013-08-01

    Massive outflows are known to exist, in the form of extended emission-line regions (EELRs), around about one-third of powerful FR II radio sources. We investigate the origin of these EELRs by studying the emission-line regions around compact-steep-spectrum (CSS) radio galaxies that are younger (10{sup 3}-10{sup 5} yr old) versions of the FR II radio galaxies. We have searched for and analyzed the emission-line regions around 11 CSS sources by taking integral field spectra using Gemini Multi-Object Spectrograph on Gemini North. We fit the [O III] {lambda}5007 line and present the velocity maps for each detected emission-line region. We find, in most cases, that the emission-line regions have multi-component velocity structures with different velocity dispersions and/or flux distributions for each component. The velocity gradients of the emission-line gas are mostly well aligned with the radio axis, suggesting a direct causal link between the outflowing gas and the radio jets. The complex velocity structure may be a result of different driving mechanisms related to the onset of the radio jets. We also present the results from the line-ratio diagnostics we used to analyze the ionization mechanism of the extended gas, which supports the scenario where the emission-line regions are ionized by a combination of active galactic nucleus radiation and shock excitation.

  3. The discovery of diffuse steep spectrum sources in Abell 2256

    NASA Astrophysics Data System (ADS)

    van Weeren, R. J.; Intema, H. T.; Oonk, J. B. R.; Röttgering, H. J. A.; Clarke, T. E.

    2009-12-01

    Context: Hierarchical galaxy formation models indicate that during their lifetime galaxy clusters undergo several mergers. An example of such a merging cluster is Abell 2256. Here we report on the discovery of three diffuse radio sources in the periphery of Abell 2256, using the Giant Metrewave Radio Telescope (GMRT). Aims: The aim of the observations was to search for diffuse ultra-steep spectrum radio sources within the galaxy cluster Abell 2256. Methods: We have carried out GMRT 325 MHz radio continuum observations of Abell 2256. V, R and I band images of the cluster were taken with the 4.2 m William Herschel Telescope (WHT). Results: We have discovered three diffuse elongated radio sources located about 1 Mpc from the cluster center. Two are located to the west of the cluster center, and one to the southeast. The sources have a measured physical extent of 170, 140 and 240 kpc, respectively. The two western sources are also visible in deep low-resolution 115-165 MHz Westerbork Synthesis Radio Telescope (WSRT) images, although they are blended into a single source. For the combined emission of the blended source we find an extreme spectral index (α) of -2.05 ± 0.14 between 140 and 351 MHz. The extremely steep spectral index suggests these two sources are most likely the result of adiabatic compression of fossil radio plasma due to merger shocks. For the source to the southeast, we find that {α < -1.45} between 1369 and 325 MHz. We did not find any clear optical counterparts to the radio sources in the WHT images. Conclusions: The discovery of the steep spectrum sources implies the existence of a population of faint diffuse radio sources in (merging) clusters with such steep spectra that they have gone unnoticed in higher frequency (⪆1 GHz) observations. Simply considering the timescales related to the AGN activity, synchrotron losses, and the presence of shocks, we find that most massive clusters should possess similar sources. An exciting possibility

  4. EGRET/COMPTEL Observations of an Unusual, Steep-Spectrum Gamma-Ray Source

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Bertsch, D. L.; Hartman, R. C.; Collmar, W.; Johnson, W. N.

    1999-01-01

    During analysis of sources below the threshold of the third EGRET catalog, we have discovered a source, named GRO J1400-3956 based on the best position, with a remarkably steep spectrum. Archival analysis of COMPTEL data shows that the spectrum must have a strong turn-over in the energy range between COMPTEL and EGRET. The EGRET data show some evidence of time variability, suggesting an AGN, but the spectral change of slope is larger than that seen for most gamma-ray blazars. The sharp cutoff resembles the high-energy spectral breaks seen in some gamma-ray pulsars. There have as yet been no OSSE observations of this source.

  5. Compact Steep Spectrum 3CR radio sources - VLBI observations at 18 CM

    NASA Astrophysics Data System (ADS)

    Fanti, C.; Fanti, R.; Parma, P.; Schilizzi, R. T.; van Breugel, W. J. M.

    1985-02-01

    Results of a program to investigate the kiloparsec-sized radio structure of a representative sample of Compact Steep Spectrum (CSS) sources from the 3CR catalog (Jenkins et al., 1977) are presented. Ten objects (3C49,67, 119, 237, 241, 268.3, 287, 303.1, 343, 343.1) have been mapped at 18 cm with a resolution of about 30 marcsec using the European VLBI Network. In some cases the VLBI data have been supplemented by MERLIN observations at the same wavelength to enhance sensitivity to large-scale structure. The overall sizes of the CSS sources range from about 0.1 to 1 or 2 arcsec, corresponding to linear sizes of the order of 1 to 10 kpc. The morphological classification ranges from double to core-jet to complex; CSS quasars are generally core-jets or complex, while CSS radio galaxies are doubles, although not necessarily simple doubles.

  6. A plethora of diffuse steep spectrum radio sources in Abell 2034 revealed by LOFAR

    NASA Astrophysics Data System (ADS)

    Shimwell, T. W.; Luckin, J.; Brüggen, M.; Brunetti, G.; Intema, H. T.; Owers, M. S.; Röttgering, H. J. A.; Stroe, A.; van Weeren, R. J.; Williams, W. L.; Cassano, R.; de Gasperin, F.; Heald, G. H.; Hoang, D. N.; Hardcastle, M. J.; Sridhar, S. S.; Sabater, J.; Best, P. N.; Bonafede, A.; Chyży, K. T.; Enßlin, T. A.; Ferrari, C.; Haverkorn, M.; Hoeft, M.; Horellou, C.; McKean, J. P.; Morabito, L. K.; Orrù, E.; Pizzo, R.; Retana-Montenegro, E.; White, G. J.

    2016-06-01

    With Low-Frequency Array (LOFAR) observations, we have discovered a diverse assembly of steep spectrum emission that is apparently associated with the intracluster medium (ICM) of the merging galaxy cluster Abell 2034. Such a rich variety of complex emission associated with the ICM has been observed in few other clusters. This not only indicates that Abell 2034 is a more interesting and complex system than previously thought but it also demonstrates the importance of sensitive and high-resolution, low-frequency observations. These observations can reveal emission from relativistic particles which have been accelerated to sufficient energy to produce observable emission or have had their high energy maintained by mechanisms in the ICM. The most prominent feature in our maps is a bright bulb of emission connected to two steep spectrum filamentary structures, the longest of which extends perpendicular to the merger axis for 0.5 Mpc across the south of the cluster. The origin of these objects is unclear, with no shock detected in the X-ray images and no obvious connection with cluster galaxies or AGNs. We also find that the X-ray bright region of the cluster coincides with a giant radio halo with an irregular morphology and a very steep spectrum. In addition, the cluster hosts up to three possible radio relics, which are misaligned with the cluster X-ray emission. Finally, we have identified multiple regions of emission with a very steep spectral index that seem to be associated with either tailed radio galaxies or a shock.

  7. FIRST-based survey of Compact Steep Spectrum sources. II. MERLIN and VLA observations of medium-sized symmetric objects

    NASA Astrophysics Data System (ADS)

    Kunert-Bajraszewska, M.; Marecki, A.; Thomasson, P.; Spencer, R. E.

    2005-09-01

    A new sample of candidate Compact Steep Spectrum (CSS) sources that are much weaker than the CSS source prototypes has been selected from the VLA FIRST catalogue. MERLIN "snapshot" observations of the sources at 5 GHz indicate that six of them have an FR II-like morphology, but are not edge-brightened as is normal for Medium-sized Symmetric Objects (MSOs) and FR IIs. Further observations of these six sources with the VLA at 4.9 GHz and MERLIN at 1.7 GHz, as well as subsequent full-track observations with MERLIN at 5 GHz of what appeared to be the two sources of greatest interest are presented. The results are discussed with reference to the established evolutionary model of CSS sources being young but in which not all of them evolve to become old objects with extended radio structures. A lack of stable fuelling in some of them may result in an early transition to a so-called coasting phase so that they fade away instead of growing to become large-scale objects. It is possible that one of the six sources (1542+323) could be labelled as a prematurely "dying" MSO or a "fader".

  8. FIRST-based survey of compact steep spectrum sources. III. MERLIN and VLBI observations of subarcsecond-scale objects

    NASA Astrophysics Data System (ADS)

    Marecki, A.; Kunert-Bajraszewska, M.; Spencer, R. E.

    2006-04-01

    Context: .According to a generally accepted paradigm, small intrinsic sizes of Compact Steep Spectrum (CSS) radio sources are a direct consequence of their youth, but in later stages of their evolution they are believed to become large-scale sources. However, this notion was established mainly for strong CSS sources.Aims.In this series of papers we test this paradigm on 60 weaker objects selected from the VLA FIRST survey. They have 5-GHz flux densities in the range 150 < S5 GHz < 550 mJy and steep spectra in the range 0.365 ≤ ν ≤ 5 GHz. The present paper is focused on sources that fulfill the above criteria and have angular sizes in the range ~0.2 arcsec -1 arcsec.Methods.Observations of 19 such sources were obtained using MERLIN in "snapshot" mode at 5 GHz. They are presented along with 1.7-GHz VLBA and 5-GHz EVN follow-up snapshot observations made for the majority of them. For one of the sources in this subsample, 1123+340, a full-track 5-GHz EVN observation was also carried out.Results.This study provides an important element to the standard theory of CSS sources, namely that in a number of them the activity of their host galaxies probably switched off quite recently and their further growth has been stopped because of that. In the case of 1123+340, the relic of a compact "dead source" is particularly well preserved by the presence of intracluster medium of the putative cluster of galaxies surrounding it.Conclusions.The observed overabundance of compact sources can readily be explained in the framework of the scenario of "premature" cessation of the activity of the host galaxy nucleus. It could also explain the relatively low radio flux densities of many such sources and, in a few cases, their peculiar, asymmetric morphologies. We propose a new interpretation of such asymmetries based on the light-travel time argument.

  9. VizieR Online Data Catalog: Ultra steep spectrum radio sources (Singh+, 2014)

    NASA Astrophysics Data System (ADS)

    Singh, V.; Beelen, A.; Wadadekar, Y.; Sirothia, S.; Ishwara-Chandra, C. H.; Basu, A.; Omont, A.; McAlpine, K.; Ivison, R. J.; Oliver, S.; Farrah, D.; Lacy, M.

    2014-11-01

    We obtained 325 MHz GMRT observations of the XMM-LSS field over sky area of ~12deg2 with synthesized beamsize ~10.2"x7.9". In the mosaiced 325MHz GMRT image the average noise rms is ~160uJy, while in the central region the average noise-rms reaches to ~120uJy. Our 325MHz observations are one of the deepest low-frequency surveys over such a wide sky area and detect ~2553/3304 radio sources at >=5.0σ with noise rms cut-off <=200/300uJy. (1 data file).

  10. An X-ray and radio study of steep-spectrum radio sources. II - Four fields from a 22 MHz polar cap survey

    NASA Technical Reports Server (NTRS)

    Dewdney, P. E.; Mchardy, I.; Willis, A. G.; Harris, D. E.; Costain, C. H.

    1991-01-01

    Four fields containing radio sources with spectral indices greater than unity at low frequencies have been observed over a wide range of radio wavelengths and at X-ray wavelengths. For most of the steep-spectrum sources no optical identifications have been found to the detection limit of the Palomar Schmidt prints, even with the positional precision of about 1 arcsec from VLA maps. This implies that the associated galaxies or clusters lie at a great distance. X-ray emission was not detected from any of the steep-spectrum radio sources. In one case, an extended source appears to be a radio halo in an uncataloged cluster of galaxies at a redshift of 0.125, and it is suggested that this object is a promising candidate for the detection of inverse Compton X-rays, since it is not a high-luminosity source of thermal X-rays.

  11. Compact steep-spectrum sources as the parent population of flat-spectrum radio-loud narrow-line Seyfert 1 galaxies

    NASA Astrophysics Data System (ADS)

    Berton, M.; Caccianiga, A.; Foschini, L.; Peterson, B. M.; Mathur, S.; Terreran, G.; Ciroi, S.; Congiu, E.; Cracco, V.; Frezzato, M.; La Mura, G.; Rafanelli, P.

    2016-06-01

    Narrow-line Seyfert 1 galaxies (NLS1s) are an interesting subclass of active galactic nuclei (AGN), which tipically does not exhibit any strong radio emission. Seven percent of them, though, are radio-loud and often show a flat radio-spectrum (F-NLS1s). This, along to the detection of γ-ray emission coming from them, is usually interpreted as a sign of a relativistic beamed jet oriented along the line of sight. An important aspect of these AGN that must be understood is the nature of their parent population, in other words how do they appear when observed under different angles. In the recent literature it has been proposed that a specific class of radio-galaxies, compact-steep sources (CSS) classified as high excitation radio galaxies (HERG), can represent the parent population of F-NLS1s. To test this hypothesis in a quantitative way,in this paper we analyzed the only two statistically complete samples of CSS/HERGs and F-NLS1s available in the literature. We derived the black hole mass and Eddington ratio distributions, and we built for the first time the radio luminosity function of F-NLS1s. Finally, we applied a relativistic beaming model to the luminosity function of CSS/HERGs, and compared the result with the observed function of F-NLS1s. We found that compact steep-spectrum sources are valid parent candidates and that F-NLS1s, when observed with a different inclination, might actually appear as CSS/HERGs.

  12. SDSS J143244.91+301435.3: a link between radio-loud narrow-line Seyfert 1 galaxies and compact steep-spectrum radio sources?

    NASA Astrophysics Data System (ADS)

    Caccianiga, A.; Antón, S.; Ballo, L.; Dallacasa, D.; Della Ceca, R.; Fanali, R.; Foschini, L.; Hamilton, T.; Kraus, A.; Maccacaro, T.; Mack, K.-H.; Marchã, M. J.; Paulino-Afonso, A.; Sani, E.; Severgnini, P.

    2014-06-01

    We present SDSS J143244.91+301435.3, a new case of a radio-loud narrow-line Seyfert 1 (RL NLS1) with a relatively high radio power (P1.4 GHz = 2.1 × 1025 W Hz-1) and large radio-loudness parameter (R1.4 = 600 ± 100). The radio source is compact with a linear size below ˜1.4 kpc but, in contrast to most of the RL NLS1 discovered so far with such a high R1.4, its radio spectrum is very steep (α = 0.93, Sν ∝ ν-α) and does not support a `blazar-like' nature. Both the small mass of the central supermassive black hole and the high accretion rate relative to the Eddington limit estimated for this object (3.2 × 107 M⊙ and 0.27, respectively, with a formal error of ˜0.4 dex for both quantities) are typical of the NLS1 class. Through modelling the spectral energy distribution of the source, we have found that the galaxy hosting SDSS J143244.91+301435.3 is undergoing quite intense star formation (SFR = 50 M⊙ yr-1), which, however, is expected to contribute only marginally (˜1 per cent) to the observed radio emission. The radio properties of SDSS J143244.91+301435.3 are remarkably similar to those of compact steep-spectrum (CSS) radio sources, a class of active galactic nuclei (AGN) mostly composed of young radio galaxies. This may suggest a direct link between these two classes of AGN, with CSS sources possibly representing the misaligned version (the so-called `parent population') of RL NLS1 showing blazar characteristics.

  13. CHANDRA VIEW OF THE ULTRA-STEEP SPECTRUM RADIO SOURCE IN A2443: MERGER SHOCK-INDUCED COMPRESSION OF FOSSIL RADIO PLASMA?

    SciTech Connect

    Clarke, T. E.; Randall, S. W.; Sarazin, C. L.; Blanton, E. L.; Giacintucci, S.

    2013-08-01

    We present a new Chandra X-ray observation of the intracluster medium in the galaxy cluster A2443, hosting an ultra-steep spectrum radio source. The data reveal that the intracluster medium is highly disturbed. The thermal gas in the core is elongated along a northwest to southeast axis and there is a cool tail to the north. We also detect two X-ray surface brightness edges near the cluster core. The edges appear to be consistent with an inner cold front to the northeast of the core and an outer shock front to the southeast of the core. The southeastern edge is coincident with the location of the radio relic as expected for shock (re)acceleration or adiabatic compression of fossil relativistic electrons.

  14. The radio-optical correlation in steep-spectrum quasars

    NASA Astrophysics Data System (ADS)

    Serjeant, Stephen; Rawlings, Steve; Lacy, Mark; Maddox, Stephen J.; Baker, Joanne C.; Clements, Dave; Lilje, Per B.

    1998-03-01

    Using complete samples of steep-spectrum quasars, we present evidence for a correlation between radio and optical luminosity which is not caused by selection effects, nor caused by an orientation dependence (such as relativistic beaming), nor a by-product of cosmic evolution. We argue that this rules out models of jet formation in which there are no parameters in common with the production of the optical continuum. This is arguably the most direct evidence to date for a close link between accretion onto a black hole and the fuelling of relativistic jets. The correlation also provides a natural explanation for the presence of aligned optical/radio structures in only the most radio-luminous high-redshift galaxies.

  15. H i Absorption in the Steep-Spectrum Superluminal Quasar 3C 216.

    PubMed

    Pihlström; Vermeulen; Taylor; Conway

    1999-11-01

    The search for H i absorption in strong compact steep-spectrum sources is a natural way to probe the neutral gas contents in young radio sources. In turn, this may provide information about the evolution of powerful radio sources. The recently improved capabilities of the Westerbork Synthesis Radio Telescope have made it possible to detect a 0.31% (19 mJy) deep neutral atomic hydrogen absorption line associated with the steep-spectrum superluminal quasar 3C 216. The redshift (z=0.67) of the source shifts the frequency of the 21 cm line down to the ultra-high-frequency (UHF) band (850 MHz). The exact location of the H i-absorbing gas remains to be determined by spectral line VLBI observations at 850 MHz. We cannot exclude that the gas might be extended on galactic scales, but we think it is more likely to be located in the central kiloparsec. Constraints from the lack of X-ray absorption probably rule out obscuration of the core region, and we argue that the most plausible site for the H i absorption is in the jet-cloud interaction observed in this source.

  16. Steep-Spectrum Radio Emission from the Low-Mass Active Galactic Nucleus GH 10

    NASA Astrophysics Data System (ADS)

    Wrobel, J. M.; Greene, J. E.; Ho, L. C.; Ulvestad, J. S.

    2008-10-01

    GH 10 is a broad-lined active galactic nucleus (AGN) energized by a black hole of mass 800,000 M⊙. It was the only object detected by Greene et al. in their Very Large Array (VLA) survey of 19 low-mass AGNs discovered by Greene & Ho. New VLA imaging at 1.4, 4.9, and 8.5 GHz reveals that GH 10's emission has an extent of less than 320 pc, has an optically thin synchrotron spectrum with a spectral index α = - 0.76 +/- 0.05 (Sν propto ν+ α), is less than 11% linearly polarized, and is steady—although poorly sampled—on timescales of weeks and years. Circumnuclear star formation cannot dominate the radio emission, because the high inferred star formation rate, 18 M⊙ yr-1, is inconsistent with the rate of less than 2 M⊙ yr-1 derived from narrow Hα and [O II] λ3727 emission. Instead, the radio emission must be mainly energized by the low-mass black hole. GH 10's radio properties match those of the steep-spectrum cores of Palomar Seyfert galaxies, suggesting that, like those galaxies, the emission is outflow-driven. Because GH 10 is radiating close to its Eddington limit, it may be a local analog of the starting conditions, or seeds, for supermassive black holes. Future imaging of GH 10 at higher linear resolution thus offers an opportunity to study the relative roles of radiative versus kinetic feedback during black hole growth.

  17. DISCOVERY OF ULTRA-STEEP SPECTRUM GIANT RADIO GALAXY WITH RECURRENT RADIO JET ACTIVITY IN ABELL 449

    SciTech Connect

    Hunik, Dominika; Jamrozy, Marek

    2016-01-20

    We report a discovery of a 1.3 Mpc diffuse radio source with extremely steep spectrum fading radio structures in the vicinity of the Abell 449 cluster of galaxies. Its extended diffuse lobes are bright only at low radio frequencies and their synchrotron age is about 160 Myr. The parent galaxy of the extended relic structure, which is the dominant galaxy within the cluster, is starting a new jet activity. There are three weak X-rays sources in the vicinity of the cluster as found in the ROSAT survey, however it is not known if they are connected with this cluster of galaxies. Just a few radio galaxy relics are currently known in the literature, as finding them requires sensitive and high angular resolution low-frequency radio observations. Objects of this kind, which also are starting a new jet activity, are important for understanding the life cycle and evolution of active galactic nuclei. A new 613 MHz map as well as the archival radio data pertaining to this object are presented and analyzed.

  18. Extragalactic Peaked-spectrum Radio Sources at Low Frequencies

    NASA Astrophysics Data System (ADS)

    Callingham, J. R.; Ekers, R. D.; Gaensler, B. M.; Line, J. L. B.; Hurley-Walker, N.; Sadler, E. M.; Tingay, S. J.; Hancock, P. J.; Bell, M. E.; Dwarakanath, K. S.; For, B.-Q.; Franzen, T. M. O.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A. D.; Lenc, E.; McKinley, B.; Morgan, J.; Offringa, A. R.; Procopio, P.; Staveley-Smith, L.; Wayth, R. B.; Wu, C.; Zheng, Q.

    2017-02-01

    We present a sample of 1483 sources that display spectral peaks between 72 MHz and 1.4 GHz, selected from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. The GLEAM survey is the widest fractional bandwidth all-sky survey to date, ideal for identifying peaked-spectrum sources at low radio frequencies. Our peaked-spectrum sources are the low-frequency analogs of gigahertz-peaked spectrum (GPS) and compact-steep spectrum (CSS) sources, which have been hypothesized to be the precursors to massive radio galaxies. Our sample more than doubles the number of known peaked-spectrum candidates, and 95% of our sample have a newly characterized spectral peak. We highlight that some GPS sources peaking above 5 GHz have had multiple epochs of nuclear activity, and we demonstrate the possibility of identifying high-redshift (z > 2) galaxies via steep optically thin spectral indices and low observed peak frequencies. The distribution of the optically thick spectral indices of our sample is consistent with past GPS/CSS samples but with a large dispersion, suggesting that the spectral peak is a product of an inhomogeneous environment that is individualistic. We find no dependence of observed peak frequency with redshift, consistent with the peaked-spectrum sample comprising both local CSS sources and high-redshift GPS sources. The 5 GHz luminosity distribution lacks the brightest GPS and CSS sources of previous samples, implying that a convolution of source evolution and redshift influences the type of peaked-spectrum sources identified below 1 GHz. Finally, we discuss sources with optically thick spectral indices that exceed the synchrotron self-absorption limit.

  19. Use of corn steep liquor as an economical nitrogen source for biosuccinic acid production by Actinobacillus succinogenes

    NASA Astrophysics Data System (ADS)

    Tan, J. P.; Jahim, J. M.; Wu, T. Y.; Harun, S.; Mumtaz, T.

    2016-06-01

    Expensive raw materials are the driving force that leads to the shifting of the petroleum-based succinic acid production into bio-based succinic acid production by microorganisms. Cost of fermentation medium is among the main factors contributing to the total production cost of bio-succinic acid. After carbon source, nitrogen source is the second largest component of the fermentation medium, the cost of which has been overlooked for the past years. The current study aimed at replacing yeast extract- a costly nitrogen source with corn steep liquor for economical production of bio-succinic acid by Actinobacillus succinogenes 130Z. In this study, a final succinic acid concentration of 20.6 g/L was obtained from the use of corn steep liquor as the nitrogen source, which was comparable with the use of yeast extract as the nitrogen source that had a final succinate concentration of 21.4 g/l. In terms of economical wise, corn steep liquor was priced at 200 /ton, which was one fifth of the cost of yeast extract at 1000 /ton. Therefore, corn steep liquor can be considered as a potential nitrogen source in biochemical industries instead of the costly yeast extract.

  20. Testing for Shock-Heated X-Ray Gas around Compact Steep Spectrum Radio Galaxies

    NASA Astrophysics Data System (ADS)

    Noel-Storr, Jacob; O'Dea, Christopher; Worrall, Diana M.; Clarke, Tracy E.; Tremblay, Grant; Baum, Stefi; Christiansen, Kevin; Mullarkey, Christopher; Mittal, Rupal

    2017-01-01

    We present Chandra and XMM-Newton X-ray, VLA radio, and optical observations of two CSS radio galaxies. B3 1445+410 is a low excitation emission line galaxy with possibly a hybrid FRI/II (or Fat Double) radio morphology. The Chandra observations are point-like and well fit with a power-law consistent with emission from a Doppler boosted core. PKS B1017-325 is a galaxy with a bent double radio morphology. The XMM-Newton observations are consistent with an ISM with a contribution from hot shocked gas. We compile selected radio and X-ray properties of the nine CSS radio galaxies with X-ray detections so far. We find that 1/3 show evidence for hot shocked gas. We note that the counts in the sources are low and the properties of the 3 sources with evidence for hot shocked gas are typical of the other CSS radio galaxies. We suggest that hot shocked gas may be typical of CSS radio galaxies due to their propagation through their host galaxies.

  1. Sediment sources, spatiotemporal variability and rates of fluvial bedload transport in glacier-connected steep mountain valleys in western Norway (Erdalen and Bødalen drainage basins)

    NASA Astrophysics Data System (ADS)

    Beylich, Achim A.; Laute, Katja

    2015-01-01

    Contemporary fluvial bedload transport rates are still very difficult to measure and, as a result of this, in many sites only quantitative data on suspended and solute transport are included in sediment budget studies carried out for defined drainage basin systems. The presented analysis of fluvial bedload dynamics in different defined subsystems of the glacier-connected Erdalen (79.5 km2) and Bødalen (60.1 km2) drainage basins in the steep fjord landscape of western Norway provides insights into (i) detectable relevant sediment sources, (ii) instream channel storage of bedload material, (iii) spatiotemporal variability and controls of bedload transport rates and bedload yields, and (iv) the absolute and relative importance of fluvial bedload transport within the sedimentary budgets of these steep cold climate mountain valleys. Rockfalls, snow avalanches, stream channel bank erosion, and fluvial transfers through small tributaries draining slope systems are relevant sediment sources for fluvial bedload transport in the main stream channels, whereas the main outlet glaciers in both drainage basins are not of importance as all bedload material delivered directly from these outlet glaciers is trapped within proglacial lakes. Narrow valleys within both drainage basin systems are characterized by a higher intensity of slope-channel coupling and display higher rates of sediment supply from slopes into the main stream channels than wider valleys. Snow avalanches are the most important sediment source in Erdalen, whereas fluvial transfers through small tributaries followed by snow avalanches are most important in Bødalen. Longer term, instream channel storage is not of great importance in the steep Bødalen drainage basin but currently plays an important role within the Erdalen drainage basin, which is characterized by a stepped longitudinal main valley bottom profile favoring deposition of bedload material within less steep main channel reaches. The mean annual bedload

  2. Flat spectrum multicomponent radio sources - Cosmic conspiracy or geometry

    SciTech Connect

    Pacholczyk, A.G.

    1981-01-01

    Compact radio sources which do not exhibit currently large flux density variations, are often characterized by spectra nearly flat over a wide range of wavelengths. Cotton et al. (1980) recently reported the results of the VLBI multifrequency interferometric and total flux density observations of a typical representative of the flat spectrum class of sources, a BL Lacertae object PKS 0735+178. If 0735+178 is indeed representative of flat spectrum sources, then some mechanism causing the component production and energy loss to be balanced must be operative among this type of radio source to maintain a flat spectrum over at least certain periods of time. This effect is referred to as 'cosmic conspiracy'. It is suggested that the flatness of spectra of this class of radio sources may be related to a specific symmetry in the radio structure, namely, to a predominantly linear, one-dimensional evolution of radio radiating material, rather than spherical, three-dimensional evolution.

  3. Corn steep liquor and fermented ammoniated condensed whey as protein sources for lactating cows and yearling heifers grazing winter native range

    SciTech Connect

    Wagner, J.J.; Lusby, K.S.; Horn, G.W.; Dvorak, M.J.

    1982-06-01

    Corn steep liquor (CSL) and fermented ammoniated condensed whey (FACW) were compared to cottonseed meal (CSM) as protein sources for wintering 61 lactating first-calf Hereford heifers and 32 yearling Hereford heifers on native range. Cattle were allotted by weight and individually fed 6 days per week for 12 weeks one of four protein treatments: negative control (NC), positive control (PC), CSL and FACW to provide .7, 1.5, .15 and 1.5 lb crude protein (CP) per day, respectively, to the lacating heifers and .2, .4, .4 and .4lb cP per day, respectively, to the yearling heifers. CMS was supplied in the CSL and FACW treatments at the same level as in the negative control. Lactating heifers fed the NC lost more (P less than .005) weight and body condition (120 lb and 1.6 units) than those fed the PC (45.8 lb and .9 units). Weight and condition losses were similar (P more than .05) for lactating heifers fed PC, CSL and FACW. Yearling heifers fed the NC lost more (P less than .005) weight than those fed the PC (49.4 vs 10.6 lb). Yearling heifers fed CSL and FACW gained more (P less than .005) weight than those fed the PC (17.6 and 9.3 vs - 10.6 lb). Feeding CSL resulted in signficantly lower rumen pH, lower ruminal acetate and higher ruminal butyrate, isovalerate and caproate levels than did feeding either control. Supplementing with FACW produced significantly lower rumen pH, higher rumen ammonia and soluble carbohydrate levels, lower ruminal acetate, and higher ruminal propionate and butyrate concentrations than did either control supplement. Corn steep liquor and FDCW appear to be effective protein sources for cows and heifers grazing winter native range.

  4. Development of a continuous broad-energy-spectrum electron source

    NASA Technical Reports Server (NTRS)

    Adamo, R. C.; Nanevicz, J. E.

    1985-01-01

    The development of a practical prototype, large-area, continuous-spectrum, multienergy electron source to simulate the lower energy (approx = 1 to 30 keV) portion of the geosynchronous orbit electron environment was investigated. The results of future materials-charging tests using this multienergy source should significantly improve the understanding of actual in-orbit charging processes and should help to resolve some of the descrepancies between predicted and observed spacecraft materials performance.

  5. What are the gigahertz peaked-spectrum radio sources?

    NASA Technical Reports Server (NTRS)

    O'Dea, C. P.; Baum, S. A.; Stanghellini, C.

    1991-01-01

    The astrophysical implications of recent radio and optical observations of the powerful compact gigahertz peaked-spectrum (GPS) radio sources are discussed. Some tentative conclusions are presented and a scenario based on the existing data is suggested. It is argued that the spectrum is due to synchrotron self-absorption, which is assumed as the basis for the present inferences from the radio spectral shape. The finding that some GPS sources have a very narrow spectral shape is consistent with the hypothesis that there is a narrow range of size scales which dominate the radio luminosity. The highly inverted LF radio spectrum is consistent with the hypothesis that the radio source is tightly confined. The conclusion that the radio polarization of these sources is systematically low is consistent either with a very tangled magnetic field or very large Faraday rotation measures. It is suggested that GPS radio sources are formed when the radio plasma is confined on the scale of the narrow-line region by an unusually dense and clumpy ISM. The existing optical spectroscopic results are also consistent with the existence of a dense and dusty nuclear ISM.

  6. The Steep Nekhoroshev's Theorem

    NASA Astrophysics Data System (ADS)

    Guzzo, M.; Chierchia, L.; Benettin, G.

    2016-03-01

    Revising Nekhoroshev's geometry of resonances, we provide a fully constructive and quantitative proof of Nekhoroshev's theorem for steep Hamiltonian systems proving, in particular, that the exponential stability exponent can be taken to be {1/(2nα_1\\cdotsα_{n-2}}) ({α_i}'s being Nekhoroshev's steepness indices and {n ≥ 3} the number of degrees of freedom). On the base of a heuristic argument, we conjecture that the new stability exponent is optimal.

  7. Optical identifications of flat-spectrum radio sources

    SciTech Connect

    Condon, J.J.; Condon, M.A.; Broderick, J.J.; Davis, M.M.

    1983-01-01

    A complete sample of radio sources with S> or =0.3 Jy at 1400 MHz, +24/sup 0/sources were made from the PSS prints on the basis of accurate position coincidence alone. Nearly all sources with ''flat'' high-frequency spectra ..cap alpha..(2695, 8085)<+0.5 are identified, and most of the identifications are QSO candidates. Those sources with flat low-frequency spectra but ..cap alpha..(2695, 8085)> or =+0.5 are usually in empty fields. The lower limits that can be assigned to the radio-optical spectral indices ..cap alpha../sub RO/ of these sources are significantly higher than the median ..cap alpha../sub RO/ of the sources with flat high-frequency spectra, so the optical characteristics of the two classes of radio source are intrinsically different. The radio and optical fluxes of flat-spectrum QSO's appear to be correlated, at least when averaged over 10/sup 2/--10/sup 3/ yr.

  8. Flat-spectrum radio sources - Cosmic conspiracy or relativistic neutrons?

    NASA Technical Reports Server (NTRS)

    Giovanoni, Peter M.; Kazanas, Demosthenes

    1990-01-01

    The intensity spectrum of the core of radio-loud AGN varies smoothly from 10 exp 8.5 to 10 to the 16th Hz, and is flat between 10 to the 9th and 10 to the 10th Hz, implying that a single emission mechanism is responsible. It is proposed here that energy is transported from the central source by relativistic neutrons which travel freely over a large volume and decay into relativistic protons. The protons produce secondary electrons which generate the observed radiation. The photon spectra thus produced are largely model-independent and flat.

  9. Can the cosmic x ray and gamma ray background be due to reflection of a steep power law spectrum and Compton scattering by relativistic electrons?

    NASA Technical Reports Server (NTRS)

    Zycki, Piotr T.; Zdziarski, Andrzej A.; Svensson, Roland

    1991-01-01

    We reconsider the recent model for the origin in the cosmic X-ray and gamma-ray background by Rogers and Field. The background in the model is due to an unresolved population of AGNs. An individual AGN spectrum contains three components: a power law with the energy index of alpha = 1.1, an enhanced reflection component, and a component from Compton scattering by relativistic electrons with a low energy cutoff at some minimum Lorentz factor, gamma(sub min) much greater than 1. The MeV bump seen in the gamma-ray background is then explained by inverse Compton emission by the electrons. We show that the model does not reproduce the shape of the observed X-ray and gamma-ray background below 10 MeV and that it overproduces the background at larger energies. Furthermore, we find the assumptions made for the Compton component to be physically inconsistent. Relaxing the inconsistent assumptions leads to model spectra even more different from that of the observed cosmic background. Thus, we can reject the hypothesis that the high-energy cosmic background is due to the described model.

  10. The power spectrum of the Point Source Catalogue redshift survey

    NASA Astrophysics Data System (ADS)

    Sutherland, W.; Tadros, H.; Efstathiou, G.; Frenk, C. S.; Keeble, O.; Maddox, S.; McMahon, R. G.; Oliver, S.; Rowan-Robinson, M.; Saunders, W.; White, S. D. M.

    1999-09-01

    We measure the redshift-space power spectrum P(k) for the recently completed IRAS Point Source Catalogue (PSC) redshift survey, which contains 14 500 galaxies over 84 per cent of the sky with 60-μm flux >=0.6 Jy. Comparison with simulations shows that our estimated errors on P(k) are realistic, and that systematic errors resulting from the finite survey volume are small for wavenumbers k >~ 0.03 h Mpc^-1. At large scales our power spectrum is intermediate between those of the earlier QDOT and 1.2-Jy surveys, but with considerably smaller error bars; it falls slightly more steeply to smaller scales. We have fitted families of CDM-like models using the Peacock-Dodds formula for non-linear evolution; the results are somewhat sensitive to the assumed small-scale velocity dispersion σ_V. Assuming a realistic σ_V ~ 300 km s^-1 yields a shape parameter Γ ~ 0.25 and normalization bσ_8 ~ 0.75; if σ_V is as high as 600 km s^-1 then Γ = 0.5 is only marginally excluded. There is little evidence for any `preferred scale' in the power spectrum or non-Gaussian behaviour in the distribution of large-scale power.

  11. Modeling runoff and erosion risk in a~small steep cultivated watershed using different data sources: from on-site measurements to farmers' perceptions

    NASA Astrophysics Data System (ADS)

    Auvet, B.; Lidon, B.; Kartiwa, B.; Le Bissonnais, Y.; Poussin, J.-C.

    2015-09-01

    This paper presents an approach to model runoff and erosion risk in a context of data scarcity, whereas the majority of available models require large quantities of physical data that are frequently not accessible. To overcome this problem, our approach uses different sources of data, particularly on agricultural practices (tillage and land cover) and farmers' perceptions of runoff and erosion. The model was developed on a small (5 ha) cultivated watershed characterized by extreme conditions (slopes of up to 55 %, extreme rainfall events) on the Merapi volcano in Indonesia. Runoff was modelled using two versions of STREAM. First, a lumped version was used to determine the global parameters of the watershed. Second, a distributed version used three parameters for the production of runoff (slope, land cover and roughness), a precise DEM, and the position of waterways for runoff distribution. This information was derived from field observations and interviews with farmers. Both surface runoff models accurately reproduced runoff at the outlet. However, the distributed model (Nash-Sutcliffe = 0.94) was more accurate than the adjusted lumped model (N-S = 0.85), especially for the smallest and biggest runoff events, and produced accurate spatial distribution of runoff production and concentration. Different types of erosion processes (landslides, linear inter-ridge erosion, linear erosion in main waterways) were modelled as a combination of a hazard map (the spatial distribution of runoff/infiltration volume provided by the distributed model), and a susceptibility map combining slope, land cover and tillage, derived from in situ observations and interviews with farmers. Each erosion risk map gives a spatial representation of the different erosion processes including risk intensities and frequencies that were validated by the farmers and by in situ observations. Maps of erosion risk confirmed the impact of the concentration of runoff, the high susceptibility of long steep

  12. Flat-Spectrum Radio Sources as Likely Counterparts of Unidentified INTEGRAL Sources (Research Note)

    NASA Technical Reports Server (NTRS)

    Molina, M.; Landi, R.; Bassani, L.; Malizia, A.; Stephen, J. B.; Bazzano, A.; Bird, A. J.; Gehrels, N.

    2012-01-01

    Many sources in the fourth INTEGRAL/IBIS catalogue are still unidentified since they lack an optical counterpart. An important tool that can help in identifying and classifying these sources is the cross-correlation with radio catalogues, which are very sensitive and positionally accurate. Moreover, the radio properties of a source, such as the spectrum or morphology, could provide further insight into its nature. In particular, flat-spectrum radio sources at high Galactic latitudes are likely to be AGN, possibly associated to a blazar or to the compact core of a radio galaxy. Here we present a small sample of 6 sources extracted from the fourth INTEGRAL/IBIS catalogue that are still unidentified or unclassified, but which are very likely associated with a bright, flat-spectrum radio object. To confirm the association and to study the source X-ray spectral parameters, we performed X-ray follow-up observations with Swift/XRT of all objects. We report in this note the overall results obtained from this search and discuss the nature of each individual INTEGRAL source. We find that 5 of the 6 radio associations are also detected in X-rays; furthermore, in 3 cases they are the only counterpart found. More specifically, IGR J06073-0024 is a flat-spectrum radio quasar at z = 1.08, IGR J14488-4008 is a newly discovered radio galaxy, while IGR J18129-0649 is an AGN of a still unknown type. The nature of two sources (IGR J07225-3810 and IGR J19386-4653) is less well defined, since in both cases we find another X-ray source in the INTEGRAL error circle; nevertheless, the flat-spectrum radio source, likely to be a radio loud AGN, remains a viable and, in fact, a more convincing association in both cases. Only for the last object (IGR J11544-7618) could we not find any convincing counterpart since the radio association is not an X-ray emitter, while the only X-ray source seen in the field is a G star and therefore unlikely to produce the persistent emission seen by INTEGRAL.

  13. Source parameters derived from seismic spectrum in the Jalisco block

    NASA Astrophysics Data System (ADS)

    Gutierrez, Q. J.; Escudero, C. R.; Nunez-Cornu, F. J.

    2012-12-01

    The direct measure of the earthquake fault dimension represent a complicated task nevertheless a better approach is using the seismic waves spectrum. With this method we can estimate the dimensions of the fault, the stress drop and the seismic moment. The study area comprises the complex tectonic configuration of Jalisco block and the subduction of the Rivera plate beneath the North American plate; this causes that occur in Jalisco some of the most harmful earthquakes and other related natural disasters. Accordingly it is important to monitor and perform studies that helps to understand the physics of earthquake rupture mechanism in the area. The main proposue of this study is estimate earthquake seismic source parameters. The data was recorded by the MARS network (Mapping the Riviera Subduction Zone) and the RESAJ network. MARS had 51 stations and settled in the Jalisco block; that is delimited by the mesoamerican trench at the west, the Colima grabben to the south, and the Tepic-Zacoalco to the north; for a period of time, of January 1, 2006 until December 31, 2007 Of this network was taken 104 events, the magnitude range of these was between 3 to 6.5 MB. RESJAL has 10 stations and is within the state of Jalisco, began to record since October 2011 and continues to record. We firs remove the trend, the mean and the instrument response, then manually chosen the S wave, then the multitaper method was used to obtain the spectrum of this wave and so estimate the corner frequency and the spectra level. We substitude the obtained in the equations of the Brune model to calculate the source parameters. Doing this we obtained the following results; the source radius was between .1 to 2 km, the stress drop was between .1 to 2 MPa.

  14. Broadband Spectral Modeling of the Extreme Gigahertz-peaked Spectrum Radio Source PKS B0008-421

    NASA Astrophysics Data System (ADS)

    Callingham, J. R.; Gaensler, B. M.; Ekers, R. D.; Tingay, S. J.; Wayth, R. B.; Morgan, J.; Bernardi, G.; Bell, M. E.; Bhat, R.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Deshpande, A. A.; Ewall-Wice, A.; Feng, L.; Greenhill, L. J.; Hazelton, B. J.; Hindson, L.; Hurley-Walker, N.; Jacobs, D. C.; Johnston-Hollitt, M.; Kaplan, D. L.; Kudrayvtseva, N.; Lenc, E.; Lonsdale, C. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Oberoi, D.; Offringa, A. R.; Ord, S. M.; Pindor, B.; Prabu, T.; Procopio, P.; Riding, J.; Srivani, K. S.; Subrahmanyan, R.; Udaya Shankar, N.; Webster, R. L.; Williams, A.; Williams, C. L.

    2015-08-01

    large population of GPS sources that have ceased activity, and that a portion of the ultra-steep-spectrum source population could be composed of these GPS sources in a relic phase.

  15. Robot Would Climb Steep Terrain

    NASA Technical Reports Server (NTRS)

    Kennedy, Brett; Ganino, Anthony; Aghazarian, Hrand; Hogg, Robert; McHerny, Michael; Garrett, Michael

    2007-01-01

    This brief describes the steep terrain access robot (STAR) -- a walking robot that has been proposed for exploring steep terrain on remote planets. The STAR would be able to climb up or down on slopes as steep as vertical, and even beyond vertical to overhangs. Its system of walking mechanisms and controls would be to react forces and maintain stability. To enable the STAR to anchor itself in the terrain on steep slopes to maintain stability and react forces, it would be necessary to equip the tips of the walking legs with new ultrasonic/ sonic drill corers (USDCs) and to develop sensors and control algorithms to enable robust utilization of the USDCs.

  16. Gamma ray cosmology: The extra galactic gamma spectrum and methods to detect the underlying source

    NASA Technical Reports Server (NTRS)

    Cline, David B.

    1990-01-01

    The possible sources of extragalactic gamma rays and methods to distinguish the different sources are discussed. The sources considered are early universe decays and annihilation of Particles, active galactic nuclei (AGN) sources, and baryon-antibaryon annihilation in a baryon symmetric cosmology. The energy spectrum and possible angular fluctuations due to these sources are described.

  17. Effects of Source Correlations on the Spectrum of Radiated Fields

    DTIC Science & Technology

    1990-09-01

    paraxial approximation, with a known result for far-zone radiant intensity of Gaussian Schell - model sources3. Spectral changes on propagation of...33 2.2 The radiation efficiency of planar Gaussian Schell - model sources ............ 34...increase in the source correlation length. Page 40. Figure 2.5: The radiation efficiency of Gaussian Schell - model sources as a function of the rms

  18. [Development of soft X-ray and vacuum ultraviolet spectrum sources].

    PubMed

    Chen, Bo; Ni, Qi-liang; Cao, Jian-lin; Li, Fu-tian; Chen, Xing-dan

    2005-03-01

    The soft X-ray and vacuum ultraviolet sources developed in CIOMP are presented. The wall-stabilized argon arc source with spectrum stability and repeatability of +/-0.3% is applied to the calibration of spectrum intensity distribution of the vacuum ultraviolet instruments as an absolute standard source. The Penning source, duobplasma source and hollow cathode source are able to produce atomic and ionic line spectra as a wavelength standard source, which covers a few nanometers to several tens nanometers with spectrum radiation stability and repeatability of +/-1.0%. In particular, the low debris laser produced plasma source with liquid aerosol spray target recently developed can emit stronger soft X-ray for soft X-ray lithography and metrology, which has a transfer efficiency as high as 0.75%/2pi x sr/2% bandwidth.

  19. Parent Perspectives on Sources of Information about Autism Spectrum Disorder Interventions in Australia

    ERIC Educational Resources Information Center

    Carlon, Sarah; Stephenson, Jennifer; Carter, Mark

    2015-01-01

    Extant research on sources of information about interventions used by parents of children with autism spectrum disorder (ASD) has provided a general overview of sources used. However, it has provided little insight into why parents view certain sources as reliable or trustworthy, or how useful parents found the information provided to them by the…

  20. Measuring the activity of a 51Cr neutrino source based on the gamma-radiation spectrum

    NASA Astrophysics Data System (ADS)

    Gorbachev, V. V.; Gavrin, V. N.; Ibragimova, T. V.; Kalikhov, A. V.; Malyshkin, Yu. M.; Shikhin, A. A.

    2015-12-01

    A technique for the measurement of activities of intense β sources by measuring the continuous gamma-radiation (internal bremsstrahlung) spectra is developed. A method for reconstructing the spectrum recorded by a germanium semiconductor detector is described. A method for the absolute measurement of the internal bremsstrahlung spectrum of 51Cr is presented.

  1. Contribution from cosmological scalar perturbations to the angular velocity spectrum of extragalactic sources

    SciTech Connect

    Marakulin, A. O. Sazhina, O. S.; Sazhin, M. V.

    2012-07-15

    The possibility of the influence of adiabatic scalar perturbations on the angular velocity spectrum of extragalactic sources is considered. The multipole expansion coefficients of the angular velocity field in terms of vector spherical harmonics are calculated. We show that there is no contribution from adiabatic perturbations to the angular spectrum for a spatially flat Universe at the dusty stage, while there is a contribution only to the electric multiple coefficients at the stage of {Lambda}-term domination. The cases of long-wavelength and short-wavelength perturbations are considered separately. The relationship between the multipole angular velocity spectrum and the primordial scalar perturbation spectrum is discussed.

  2. Measurement of an inverse Compton scattering source local spectrum using k-edge filters

    SciTech Connect

    Golosio, Bruno; Oliva, Piernicola; Carpinelli, Massimo; Endrizzi, Marco; Delogu, Pasquale; Pogorelsky, Igor; Yakimenko, Vitaly

    2012-04-16

    X-ray sources based on the inverse Compton scattering process are attracting a growing interest among scientists, due to their extremely fast pulse, quasi-monochromatic spectrum, and relatively high intensity. The energy spectrum of the x-ray beam produced by inverse Compton scattering sources in a fixed observation direction is a quasi-monochromatic approximately Gaussian distribution. The mean value of this distribution varies with the scattering polar angle between the electron beam direction and the x-ray beam observation direction. Previous works reported experimental measurements of the mean energy as a function of the polar angle. This work introduces a method for the measurement of the whole local energy spectrum (i.e., the spectrum in a fixed observation direction) of the x-ray beam yielded by inverse Compton scattering sources, based on a k-edge filtering technique.

  3. The Population of KPC-Scale Flat-Spectrum Radio Sources

    NASA Astrophysics Data System (ADS)

    Augusto, Pedro; Wilkinson, Peter N.; Browne, Ian W. A.

    In this paper we present a subsample of 55 flat-spectrum radio sources dominated by (~ 100 mas) kpc-scale structure, selected from a parent sample of 1665 VLA sources. Most are core-jets and 23 are CSO/MSO candidates. Properties of the subsample are discussed.

  4. Energy spectrum of extragalactic gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Protheroe, R. J.

    1985-01-01

    The result of Monte Carlo electron photon cascade calculations for propagation of gamma rays through regions of extragalactic space containing no magnetic field are given. These calculations then provide upper limits to the expected flux from extragalactic sources. Since gamma rays in the 10 to the 14th power eV to 10 to the 17th power eV energy range are of interest, interactions of electrons and photons with the 3 K microwave background radiation are considered. To obtain an upper limit to the expected gamma ray flux from sources, the intergalactic field is assumed to be so low that it can be ignored. Interactions with photons of the near-infrared background radiation are not considered here although these will have important implications for gamma rays below 10 to the 14th power eV if the near infrared background radiation is universal. Interaction lengths of electrons and photons in the microwave background radiation at a temperature of 2.96 K were calculated and are given.

  5. Analysis of x-ray spectrum obtained in electron cyclotron resonance x-ray source

    SciTech Connect

    Baskaran, R.; Selvakumaran, T.S.; Sunil Sunny, C.

    2006-03-15

    The analysis of the x-ray spectrum obtained in electron cyclotron resonance (ECR) x-ray source is carried out. Assuming single-particle motion, the electron acceleration and its final energy are calculated for TE{sub 111} cylindrical cavity field and uniform external dc magnetic field. In the calculation, initial coordinates of 40 000 electrons were uniformly selected over the central plane of the cavity using random number generator. The final energy of each electron when it hits the wall is stored and the electron energy distribution is obtained. Using the general purpose Monte Carlo N-particle transport code version 4A, the geometry of the ECR x-ray source is modeled. The x-ray energy spectrum is calculated for the geometry model and the numerically calculated electron energy distribution. The calculated x-ray spectrum is compared with the experimentally measured x-ray spectrum.

  6. Broadband source spectrum, seismic energy, and stress drop of the 1989 Macquarie Ridge earthquake

    SciTech Connect

    Houston, H. )

    1990-06-01

    The author computes the broadband source spectrum at periods from 1 to 50 seconds using teleseismic P body waves of the May 23, 1989 Macquarie Ridge earthquake (M{sub W} = 8.1) recorded by the GDSN, GEOSCOPE, and IDA networks. The average source spectrum is obtained by windowing, tapering, and Fourier-transforming P waves, removing from the spectra the effects of attenuation, geometrical spreading, and radiation pattern, and averaging logarithmically over the stations. The source spectrum for the strike-slip Macquarie Ridge earthquake is higher than an average source spectrum of seven recent large earthquakes (scaled to be comparable to a M{sub W} = 8.1 earthquake) by a factor of 2 to 3 at periods of 1 to 20 seconds. These other earthquakes were underthrusting events in subduction zones. Using Haskell's formulation assuming a point source with no directivity, she estimates the seismically radiated energy from the source spectrum by integrating the square of the source spectrum in velocity and scaling the result. The seismic energy thus estimated for the Macquarie Ridge earthquake is 3 to 8 {times} 10{sup 23} ergs. An Orowan stress drop can be obtained from the seismic energy and moment. The Orowan stress drop for the Macquarie Ridge earthquake is about 20 to 50 bars, much higher than similarly determined stress drops of other recent large earthquakes. There is a correlation between the Orowan stress drops and time since the last earthquake of comparable or larger magnitude for seven recent large earthquakes. This correlation suggests that a healing process operates that may control the mechanical strength of the fault and is important on time scales of tens to hundreds of years.

  7. Optical Spectra of Candidate International Celestial Reference Frame (ICRF) Flat-spectrum Radio Sources. III.

    NASA Astrophysics Data System (ADS)

    Titov, O.; Pursimo, T.; Johnston, Helen M.; Stanford, Laura M.; Hunstead, Richard W.; Jauncey, David L.; Zenere, Katrina A.

    2017-04-01

    In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ∼160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58 m European Southern Observatory New Technology Telescope, and the two 8.2 m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.

  8. An equivalent n-source for WGPu derived from a spectrum-shifted PuBe source

    NASA Astrophysics Data System (ADS)

    Ghita, Gabriel; Sjoden, Glenn; Baciak, James; Walker, Scotty; Cornelison, Spring

    2008-04-01

    We have designed, built, and laboratory-tested a unique shield design that transforms the complex neutron spectrum from PuBe source neutrons, generated at high energies, to nearly exactly the neutron signature leaking from a significant spherical mass of weapons grade plutonium (WGPu). This equivalent "X-material shield assembly" (Patent Pending) enables the harder PuBe source spectrum (average energy of 4.61 MeV) from a small encapsulated standard 1-Ci PuBe source to be transformed, through interactions in the shield, so that leakage neutrons are shifted in energy and yield to become a close reproduction of the neutron spectrum leaking from a large subcritical mass of WGPu metal (mean energy 2.11 MeV). The utility of this shielded PuBe surrogate for WGPu is clear, since it directly enables detector field testing without the expense and risk of handling large amounts of Special Nuclear Materials (SNM) as WGPu. Also, conventional sources using Cf-252, which is difficult to produce, and decays with a 2.7 year half life, could be replaced by this shielded PuBe technology in order to simplify operational use, since a sealed PuBe source relies on Pu-239 (T½=24,110 y), and remains viable for more than hundreds of years.

  9. Inhomogeneity in cosmic ray sources as the origin of the electron spectrum and the PAMELA anomaly.

    PubMed

    Shaviv, Nir J; Nakar, Ehud; Piran, Tsvi

    2009-09-11

    We show that inhomogeneity of cosmic ray (CR) sources, due to the concentration of supernova remnants (SNRs) towards the galactic spiral arms, can naturally explain the anomalous increase in the positron/electron ratio observed by PAMELA. We consistently recover the observed positron fraction between 1 and 100 GeV using SNRs as the sole source of CRs. The contribution of a few known nearby SNRs dominates the CR electron spectrum above approximately 100 GeV, leading to the relatively flat spectrum observed by Fermi and to the sharp cutoff observed by H.E.S.S.

  10. THE LOW-FREQUENCY RADIO CATALOG OF FLAT-SPECTRUM SOURCES

    SciTech Connect

    Massaro, F.; Giroletti, M.; D'Abrusco, R.; Paggi, A.; Cowperthwaite, Philip S.; Masetti, N.; Tosti, G.; Funk, S.

    2014-07-01

    A well known property of the γ-ray sources detected by Cos-B in the 1970s, by the Compton Gamma-Ray Observatory in the 1990s, and recently by the Fermi observations is the presence of radio counterparts, particularly for those associated with extragalactic objects. This observational evidence is the basis of the radio-γ-ray connection established for the class of active galactic nuclei known as blazars. In particular, the main spectral property of the radio counterparts associated with γ-ray blazars is that they show a flat spectrum in the GHz frequency range. Our recent analysis dedicated to search blazar-like candidates as potential counterparts for the unidentified γ-ray sources allowed us to extend the radio-γ-ray connection in the MHz regime. We also showed that blazars below 1 GHz maintain flat radio spectra. Thus, on the basis of these new results, we assembled a low-frequency radio catalog of flat-spectrum sources built by combining the radio observations of the Westerbork Northern Sky Survey and of the Westerbork in the southern hemisphere catalog with those of the NRAO Very Large Array Sky survey (NVSS). This could be used in the future to search for new, unknown blazar-like counterparts of γ-ray sources. First, we found NVSS counterparts of Westerbork Synthesis Radio Telescope radio sources, and then we selected flat-spectrum radio sources according to a new spectral criterion, specifically defined for radio observations performed below 1 GHz. We also described the main properties of the catalog listing 28,358 radio sources and their logN-logS distributions. Finally, a comparison with the Green Bank 6 cm radio source catalog was performed to investigate the spectral shape of the low-frequency flat-spectrum radio sources at higher frequencies.

  11. The Parkes quarter-Jansky flat-spectrum sample. I. Sample selection and source identifications

    NASA Astrophysics Data System (ADS)

    Jackson, C. A.; Wall, J. V.; Shaver, P. A.; Kellermann, K. I.; Hook, I. M.; Hawkins, M. R. S.

    2002-04-01

    We present a new sample of quarter-Jansky flat-spectrum radio sources selected to search for high-redshift quasars and to study the evolution of the flat-spectrum quasar population. The sample comprises 878 radio sources selected from the Parkes catalogues with spectral indices alpha 5 GHz_2.7 GHz >=-0.4 where Snu ~ nu alpha . The sample covers all right ascensions and the declination range from -80fdg0 to +2fdg5 , excluding low galactic latitudes (mid b mid < 10deg) and the Magellanic Cloud regions. We have obtained improved radio source positions, firstly to reconfirm the majority of the existing identifications, and secondly, using digitized sky-survey data and deep B, Gunn-i and Gunn-z CCD-imaging, to find optical identifications for 223 previously-unidentified sources. We present the final catalogue of 878 flat-spectrum sources: 827 are compact radio sources identified with galaxies, quasars and BL Lac objects, 38 have either extended radio structure or are identified with Galactic objects (PN, HII or non-compact radio source), 4 are obscured by Galactic stars, and 9 (1 per cent of the total sample) remain unidentified. Full Appendices A-D are only available in electronic form at http://www.edpsciences.org

  12. Naturally inflating on steep potentials through electromagnetic dissipation

    SciTech Connect

    Anber, Mohamed M.; Sorbo, Lorenzo

    2010-02-15

    In models of natural inflation, the inflaton is an axionlike particle. Unfortunately, axion potentials in UV-complete theories appear to be too steep to drive inflation. We show that, even for a steep potential, natural inflation can occur if the coupling between axion and gauge fields is taken into account. Because of this coupling, quanta of the gauge field are produced by the rolling of the axion. If the coupling is large enough, such a dissipative effect slows down the axion, leading to inflation even for a steep potential. The spectrum of perturbations is quasiscale invariant, but in the simplest construction its amplitude is larger than 10{sup -5}. We discuss a possible way out of this problem.

  13. The Integrated X-Ray Spectrum of Galactic Populations of Luminous Supersoft X-Ray Sources

    NASA Technical Reports Server (NTRS)

    DiStefano, R.; Becker, C. M.; Fabbiano, G.

    1996-01-01

    We compute the composite X-ray spectrum of a population of unresolved SSS's in a spiral galaxy such as our own or M31. The sources are meant to represent the total underlying population corresponding to all sources which have bolometric luminosities in the range of 10(exp 37) - 10(exp 38) ergs/s and kT on the order of tens of eV. These include close-binary supersoft sources, symbiotic novae, and planetary nebulae, for example. In order to determine whether the associated X-ray signal would be detectable, we also 'seed' the galaxy with other types of X-ray sources, specifically low-mass X-ray binaries (LMXB's) and high-mass X-ray binaries (HMXB's). We find that the total spectrum due to SSS's, LMXB's, and HMXB's exhibits a soft peak which owes its presence to the SSS population. Preliminary indications are that this soft peak may be observable.

  14. Regularized least-squares migration of simultaneous-source seismic data with adaptive singular spectrum analysis.

    PubMed

    Li, Chuang; Huang, Jian-Ping; Li, Zhen-Chun; Wang, Rong-Rong

    2017-01-01

    Simultaneous-source acquisition has been recognized as an economic and efficient acquisition method, but the direct imaging of the simultaneous-source data produces migration artifacts because of the interference of adjacent sources. To overcome this problem, we propose the regularized least-squares reverse time migration method (RLSRTM) using the singular spectrum analysis technique that imposes sparseness constraints on the inverted model. Additionally, the difference spectrum theory of singular values is presented so that RLSRTM can be implemented adaptively to eliminate the migration artifacts. With numerical tests on a flat layer model and a Marmousi model, we validate the superior imaging quality, efficiency and convergence of RLSRTM compared with LSRTM when dealing with simultaneous-source data, incomplete data and noisy data.

  15. Examining the Clinical Correlates of Autism Spectrum Disorder in Youth by Ascertainment Source

    ERIC Educational Resources Information Center

    Joshi, Gagan; Faraone, Stephen V.; Wozniak, Janet; Petty, Carter; Fried, Ronna; Galdo, Maribel; Furtak, Stephannie L.; McDermott, Katie; Epstien, Cecily; Walker, Rosemary; Caron, Ashley; Feinberg, Leah; Biederman, Joseph

    2014-01-01

    To examine whether presentation of autism spectrum disorder (ASD) and associated patterns of psychiatric comorbidity and dysfunction vary by referral source. ASD youth referred to a specialized ambulatory program for ASD (N = 143) were compared to ASD youth referred to a general child psychiatry clinic (N = 217). More ASD clinic youth met criteria…

  16. Investigation of the neutron spectrum of americium-beryllium sources by Bonner sphere spectrometry

    NASA Astrophysics Data System (ADS)

    Bedogni, R.; Domingo, C.; Roberts, N.; Thomas, D. J.; Chiti, M.; Esposito, A.; Garcia, M. J.; Gentile, A.; Liu, Z. Z.; de-San-Pedro, M.

    2014-11-01

    Americium-beryllium neutron sources are certainly the most widely used in neutron dosimetry laboratories, basically due to their long half-life and their energy distribution, which covers the energy domain of interest for many applications in ambient and personal dosimetry. Nevertheless, the spectrum of this source depends on the materials and dimension of the capsule and on the amount and physical-chemical properties of the active material, thus affecting relevant quantities such as the spectrum-averaged fluence-to-dose equivalent conversion coefficient. A EURAMET (European Association of National Metrology Institutes) project (n. 1104) was initiated to experimentally investigate how the neutron spectrum changes for different source sizes and encapsulations with a view to providing improved data for a planned revision of the ISO 8529 Standard Series. The experimental campaign was carried out in the low scatter facility at NPL. Here three different Bonner sphere spectrometers, BSSs, were exposed to the neutron fields produced by three different neutron sources formats: one X3 capsule (1 Ci) and two X14 capsules (10 Ci and 15 Ci). The specific advantage of the BSS is the large sensitivity to low-energy neutrons (E<0.1 MeV) which is the component expected to be most affected by the capsule-to-capsule variations and the component which is least well known. This paper summarises the results of the campaign with emphasis on (1) estimating the low-energy component of the Am-Be neutron spectrum, according to the encapsulation type; (2) evaluating the coherence between the Bonner spheres data and the previous studies performed with high-resolution spectrometers but limited in energy to E>0.1 MeV; (3) understanding whether the ISO-recommended Am-Be spectrum needs to be amended, and for which source formats.

  17. Extension of the angular spectrum method to calculate pressure from a spherically curved acoustic source.

    PubMed

    Vyas, Urvi; Christensen, Douglas A

    2011-11-01

    The angular spectrum method is an accurate and computationally efficient method for modeling acoustic wave propagation. The use of the typical 2D fast Fourier transform algorithm makes this a fast technique but it requires that the source pressure (or velocity) be specified on a plane. Here the angular spectrum method is extended to calculate pressure from a spherical transducer-as used extensively in applications such as magnetic resonance-guided focused ultrasound surgery-to a plane. The approach, called the Ring-Bessel technique, decomposes the curved source into circular rings of increasing radii, each ring a different distance from the intermediate plane, and calculates the angular spectrum of each ring using a Fourier series. Each angular spectrum is then propagated to the intermediate plane where all the propagated angular spectra are summed to obtain the pressure on the plane; subsequent plane-to-plane propagation can be achieved using the traditional angular spectrum method. Since the Ring-Bessel calculations are carried out in the frequency domain, it reduces calculation times by a factor of approximately 24 compared to the Rayleigh-Sommerfeld method and about 82 compared to the Field II technique, while maintaining accuracies of better than 96% as judged by those methods for cases of both solid and phased-array transducers.

  18. Spectrum synthesis for a spectrally tunable light source based on a DMD-convex grating Offner configuration

    NASA Astrophysics Data System (ADS)

    Ma, Suodong; Pan, Qiao; Shen, Weimin

    2016-09-01

    As one kind of light source simulation devices, spectrally tunable light sources are able to generate specific spectral shape and radiant intensity outputs according to different application requirements, which have urgent demands in many fields of the national economy and the national defense industry. Compared with the LED-type spectrally tunable light source, the one based on a DMD-convex grating Offner configuration has advantages of high spectral resolution, strong digital controllability, high spectrum synthesis accuracy, etc. As a key link of the above type light source to achieve target spectrum outputs, spectrum synthesis algorithm based on spectrum matching is therefore very important. An improved spectrum synthesis algorithm based on linear least square initialization and Levenberg-Marquardt iterative optimization is proposed in this paper on the basis of in-depth study of the spectrum matching principle. The effectiveness of the proposed method is verified by a series of simulations and experimental works.

  19. Algorithm for Building a Spectrum for NREL's One-Sun Multi-Source Simulator: Preprint

    SciTech Connect

    Moriarty, T.; Emery, K.; Jablonski, J.

    2012-06-01

    Historically, the tools used at NREL to compensate for the difference between a reference spectrum and a simulator spectrum have been well-matched reference cells and the application of a calculated spectral mismatch correction factor, M. This paper describes the algorithm for adjusting the spectrum of a 9-channel fiber-optic-based solar simulator with a uniform beam size of 9 cm square at 1-sun. The combination of this algorithm and the One-Sun Multi-Source Simulator (OSMSS) hardware reduces NREL's current vs. voltage measurement time for a typical three-junction device from man-days to man-minutes. These time savings may be significantly greater for devices with more junctions.

  20. Neutron dosimetry, moderated energy spectrum, and neutron capture therapy for californium-252 medical sources

    NASA Astrophysics Data System (ADS)

    Rivard, Mark Joseph

    Examination of neutron dosimetry for 252Cf has been conducted using calculative and experimental means. Monte Carlo N-Particle (MCNP) transport code was used in a distributed computing environment as a parallel virtual machine (PVM) to determine the absorbed neutron dose and neutron energy spectrum from 252Cf in a variety of clinically relevant materials. Herein, a Maxwellian spectrum was used to model the 252Cf neutron emissions within these materials. 252Cf mixed-field dosimetry of Applicator Tube (AT) type sources was measured using 1.0 and 0.05 cm3 tissue-equivalent ion chambers and a miniature GM counter. A dosimetry protocol was formulated similar that of ICRU 45. The 252Cf AT neutron dosimetry was determined in the cylindrical coordinate system formalism recommended by the AAPM Task Group 43. These results demonstrated the overwhelming dependence of dosimetry on the source geometry factor as there was no significant neutron attenuation within the source or encapsulation. Gold foils and TLDs were used to measure the thermal flux in the vicinity of 252Cf AT sources to compare with the results calculated using MCNP. As the fast neutron energy spectrum did not markedly changed at increasing distances from the AT source, neutron dosimetry results obtained with paired ion chambers using fixed sensitivity factors agreed well with MCNP results and those in the literature. Calculations of moderated 252Cf neutron energy spectrum with various loadings of 10B and 157Gd were performed, in addition to analysis of neutron capture therapy dosimetry with these isotopes. Radiological concerns such as personnel exposure and shielding of 252Cf emissions were examined. Feasibility of a high specific-activity 252Cf HDR source was investigated through radiochemical and metallurgical studies using stand-ins such as Tb, Gd and 249Cf. Issues such as capsule burst strength due to helium production for a variety of proposed HDR sources were addressed. A recommended 252Cf source

  1. The nuclear region of low luminosity flat radio spectrum sources. II. Emission-line spectra

    NASA Astrophysics Data System (ADS)

    Gonçalves, A. C.; Serote Roos, M.

    2004-01-01

    We report on the spectroscopic study of 19 low luminosity Flat Radio Spectrum (LL FRS) sources selected from Marchã's et al. (\\cite{March96}) 200 mJy sample. In the optical, these objects are mainly dominated by the host galaxy starlight. After correcting the data for this effect, we obtain a new set of spectra clearly displaying weak emission lines; such features carry valuable information concerning the excitation mechanisms at work in the nuclear regions of LL FRS sources. We have used a special routine to model the spectra and assess the intensities and velocities of the emission lines; we have analyzed the results in terms of diagnostic diagrams. Our analysis shows that 79% of the studied objects harbour a Low Ionization Nuclear Emission-line Region (or LINER) whose contribution was swamped by the host galaxy starlight. The remaining objects display a higher ionization spectrum, more typical of Seyferts; due to the poor quality of the spectra, it was not possible to identify any possible large Balmer components. The fact that we observe a LINER-type spectrum in LL FRS sources supports the idea that some of these objects could be undergoing an ADAF phase; in addition, such a low ionization emission-line spectrum is in agreement with the black hole mass values and sub-Eddington accretion rates published for some FRS sources. Based on observations collected at the Multiple Mirror Telescope on Mt. Hopkins. Full Fig. 1 is only available in electronic form at http://www.edpsciences.org

  2. Correlation equation for the marine drag coefficient and wave steepness

    NASA Astrophysics Data System (ADS)

    Foreman, Richard J.; Emeis, Stefan

    2012-09-01

    This work questions, starting from dimensional considerations, the generality of the belief that the marine drag coefficient levels off with increasing wind speed. Dimensional analysis shows that the drag coefficient scales with the wave steepness as opposed to a wave-age scaling. A correlation equation is employed here that uses wave steepness scaling at low aspect ratios (inverse wave steepnesses) and a constant drag coefficient at high aspect ratios. Invoked in support of the correlation are measurements sourced from the literature and at the FINO1 platform in the North Sea. The correlation equation is then applied to measurements recorded from buoys during the passage of hurricanes Rita, Katrina (2005) and Ike (2008). Results show that the correlation equation anticipates the expected levelling off in deeper water, but a drag coefficient more consistent with a Charnock type relation is also possible in more shallower water. Some suggestions are made for proceeding with a higher-order analysis than that conducted here.

  3. Evaluation of the beta energy spectrum from a distributed uranium mill tailings source

    SciTech Connect

    Reif, R.H.; Martz, D.E.; Carlson, D.S.; Turner, J.B. )

    1993-10-01

    The beta energy spectra from uranium mill tailings, 90Sr with different absorber thicknesses, and a uranium metal slab were measured and compared to select an appropriate beta source for calibrating a personal dosimeter to measure shallow dose equivalent when exposed to uranium mill tailings. The measured beta energy spectrum from the 90Sr source, with a 111 mg cm-2 cover thickness, was selected as a possible calibration source for a personnel dosimeter. The dose equivalent rate to the skin at 1 cm from a distributed tailings source of infinite thickness, with a 226Ra activity of 56 Bq g-1 (1.5 x 10(3) pCi g-1), was measured to be 0.024 mSv h-1 (2.4 mrem h-1).

  4. Evaluation of the beta energy spectrum from a distributed uranium mill tailings source.

    PubMed

    Reif, R H; Martz, D E; Carlson, D S; Turner, J B

    1993-10-01

    The beta energy spectra from uranium mill tailings, 90Sr with different absorber thicknesses, and a uranium metal slab were measured and compared to select an appropriate beta source for calibrating a personal dosimeter to measure shallow dose equivalent when exposed to uranium mill tailings. The measured beta energy spectrum from the 90Sr source, with a 111 mg cm-2 cover thickness, was selected as a possible calibration source for a personnel dosimeter. The dose equivalent rate to the skin at 1 cm from a distributed tailings source of infinite thickness, with a 226Ra activity of 56 Bq g-1 (1.5 x 10(3) pCi g-1), was measured to be 0.024 mSv h-1 (2.4 mrem h-1).

  5. Sensitivity of neutrinos to the supernova turbulence power spectrum: Point source statistics

    SciTech Connect

    Kneller, James P.; Kabadi, Neel V.

    2015-07-16

    The neutrinos emitted from the proto-neutron star created in a core-collapse supernova must run through a significant amount of turbulence before exiting the star. Turbulence can modify the flavor evolution of the neutrinos imprinting itself upon the signal detected here at Earth. The turbulence effect upon individual neutrinos, and the correlation between pairs of neutrinos, might exhibit sensitivity to the power spectrum of the turbulence, and recent analysis of the turbulence in a two-dimensional hydrodynamical simulation of a core-collapse supernova indicates the power spectrum may not be the Kolmogorov 5 /3 inverse power law as has been previously assumed. In this paper we study the effect of non-Kolmogorov turbulence power spectra upon neutrinos from a point source as a function of neutrino energy and turbulence amplitude at a fixed postbounce epoch. We find the two effects of turbulence upon the neutrinos—the distorted phase effect and the stimulated transitions—both possess strong and weak limits in which dependence upon the power spectrum is absent or evident, respectively. Furthermore, since neutrinos of a given energy will exhibit these two effects at different epochs of the supernova each with evolving strength, we find there is sensitivity to the power spectrum present in the neutrino burst signal from a Galactic supernova.

  6. Sensitivity of neutrinos to the supernova turbulence power spectrum: Point source statistics

    DOE PAGES

    Kneller, James P.; Kabadi, Neel V.

    2015-07-16

    The neutrinos emitted from the proto-neutron star created in a core-collapse supernova must run through a significant amount of turbulence before exiting the star. Turbulence can modify the flavor evolution of the neutrinos imprinting itself upon the signal detected here at Earth. The turbulence effect upon individual neutrinos, and the correlation between pairs of neutrinos, might exhibit sensitivity to the power spectrum of the turbulence, and recent analysis of the turbulence in a two-dimensional hydrodynamical simulation of a core-collapse supernova indicates the power spectrum may not be the Kolmogorov 5 /3 inverse power law as has been previously assumed. Inmore » this paper we study the effect of non-Kolmogorov turbulence power spectra upon neutrinos from a point source as a function of neutrino energy and turbulence amplitude at a fixed postbounce epoch. We find the two effects of turbulence upon the neutrinos—the distorted phase effect and the stimulated transitions—both possess strong and weak limits in which dependence upon the power spectrum is absent or evident, respectively. Furthermore, since neutrinos of a given energy will exhibit these two effects at different epochs of the supernova each with evolving strength, we find there is sensitivity to the power spectrum present in the neutrino burst signal from a Galactic supernova.« less

  7. Constraining high-redshift X-ray sources with next generation 21-cm power spectrum measurements

    NASA Astrophysics Data System (ADS)

    Ewall-Wice, Aaron; Hewitt, Jacqueline; Mesinger, Andrei; Dillon, Joshua S.; Liu, Adrian; Pober, Jonathan

    2016-05-01

    We use the Fisher matrix formalism and seminumerical simulations to derive quantitative predictions of the constraints that power spectrum measurements on next-generation interferometers, such as the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometre Array (SKA), will place on the characteristics of the X-ray sources that heated the high-redshift intergalactic medium. Incorporating observations between z = 5 and 25, we find that the proposed 331 element HERA and SKA phase 1 will be capable of placing ≲ 10 per cent constraints on the spectral properties of these first X-ray sources, even if one is unable to perform measurements within the foreground contaminated `wedge' or the FM band. When accounting for the enhancement in power spectrum amplitude from spin temperature fluctuations, we find that the observable signatures of reionization extend well beyond the peak in the power spectrum usually associated with it. We also find that lower redshift degeneracies between the signatures of heating and reionization physics lead to errors on reionization parameters that are significantly greater than previously predicted. Observations over the heating epoch are able to break these degeneracies and improve our constraints considerably. For these two reasons, 21-cm observations during the heating epoch significantly enhance our understanding of reionization as well.

  8. Source spectrum and source time function of volcanic tremor determined with a dense seismic network near the summit crater of Izu-Oshima volcano, Japan

    NASA Astrophysics Data System (ADS)

    Oikawa, Jun; Ida, Yoshiaki; Yamaoka, Koshun

    1994-05-01

    Digital seismic records of episodic volcanic tremor, obtained with a dense seismic network near the summit crater of Izu-Oshima volcano, were analyzed to determine source spectrum and source time function. Source spectrum and transfer function could be separated because the seismic records showed a systematic change with distance from the source. The source spectrum of velocity amplitude had a different frequency, f, dependence above and below a corner frequency of 8 to 10 Hz. At high ranges, the spectrum was proportional to f(exp -2), while at low ranges, it was proportional to f(exp 2). Inversion of this frequency-dependent source spectrum yields a source time function that can be represented by an impulse that attenuates in about 0.1 s. Repeated impulses could explain observed volcanic tremor that persists for many minutes or longer and that have complicated phase spectra. The source spectrum gives an energy release rate of about 5.2 x 10(exp 2) J/s, so that the total energy released is about 1.0 x 10(exp 5) J during a tremor episode of about 3 min at Izu-Oshima. Such energy release is comparable to the seismic energy released by an earthquake of magnitude 0.1.

  9. Discovery of the Hard Spectrum VHE γ-Ray Source HESS J1641-463

    NASA Astrophysics Data System (ADS)

    Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Angüner, E. O.; Backes, M.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Birsin, E.; Biteau, J.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Bulik, T.; Carrigan, S.; Casanova, S.; Chadwick, P. M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Conrad, J.; Couturier, C.; Cui, Y.; Dalton, M.; Davids, I. D.; Degrange, B.; Deil, C.; deWilt, P.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; O'C. Drury, L.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Edwards, T.; Egberts, K.; Eger, P.; Espigat, P.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Grondin, M.-H.; Grudzińska, M.; Hadasch, D.; Häffner, S.; Hahn, J.; Harris, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Ivascenko, A.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Janiak, M.; Jankowsky, F.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Kieffer, M.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Méhault, J.; Meintjes, P. J.; Menzler, U.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Morå, K.; Moulin, E.; Murach, T.; de Naurois, M.; Niemiec, J.; Nolan, S. J.; Oakes, L.; Odaka, H.; Ohm, S.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, R. D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Poon, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reichardt, I.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tluczykont, M.; Trichard, C.; Valerius, K.; van Eldik, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Völk, H. J.; Volpe, F.; Vorster, M.; Vuillaume, T.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; Ward, M.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.; Fukui, Y.; Sano, H.; Fukuda, T.; Yoshiike, S.; H. E. S. S. Collaboration

    2014-10-01

    This Letter reports the discovery of a remarkably hard spectrum source, HESS J1641-463, by the High Energy Stereoscopic System (H.E.S.S.) in the very high energy (VHE) domain. HESS J1641-463 remained unnoticed by the usual analysis techniques due to confusion with the bright nearby source HESS J1640-465. It emerged at a significance level of 8.5 standard deviations after restricting the analysis to events with energies above 4 TeV. It shows a moderate flux level of phi(E>1 TeV) = (3.64 ± 0.44stat ± 0.73sys) × 10-13 cm-2 s-1, corresponding to 1.8% of the Crab Nebula flux above the same energy, and a hard spectrum with a photon index of Γ = 2.07 ± 0.11stat ± 0.20sys. It is a point-like source, although an extension up to a Gaussian width of σ = 3 arcmin cannot be discounted due to uncertainties in the H.E.S.S. point-spread function. The VHE γ-ray flux of HESS J1641-463 is found to be constant over the observed period when checking time binnings from the year-by-year to the 28 minute exposure timescales. HESS J1641-463 is positionally coincident with the radio supernova remnant SNR G338.5+0.1. No X-ray candidate stands out as a clear association; however, Chandra and XMM-Newton data reveal some potential weak counterparts. Various VHE γ-ray production scenarios are discussed. If the emission from HESS J1641-463 is produced by cosmic ray protons colliding with the ambient gas, then their spectrum must extend close to 1 PeV. This object may represent a source population contributing significantly to the galactic cosmic ray flux around the knee.

  10. [Decomposition and analysis of the natural source SLF spectrum using curvelet transform method].

    PubMed

    Jiang, Hong-bo; Chen, Chao; Qin, Qi-ming

    2012-02-01

    Because natural source super low frequency (SLF) electromagnetic detection equipment receives wideband multi-source signal, how to decompose the signal to filter out the interference signal was a key factor for the application of natural source SLF electromagnetic detection technology. In the present article, the detection equipment developed by Peking University was used to survey the coal bed methane data in the Qinshui basin, Shanxi province, and the curvelet transform method was employed to decompose those data. The analysis results indicated that the high-frequency information coming from the decomposition is the interference signals mainly generated by lightning in the atmospheric and directly received by the detection equipment, while the low frequency signal mainly contains the target information. So the reconstructed curve based on the low-frequency information was more favorable for the interpretation of the target, compared with the original spectrum curve. But the curvelet transform method could not remove the artificial frequency signal.

  11. Contribution from individual nearby sources to the spectrum of high-energy cosmic-ray electrons

    NASA Astrophysics Data System (ADS)

    Sedrati, R.; Attallah, R.

    2014-04-01

    In the last few years, very important data on high-energy cosmic-ray electrons and positrons from high-precision space-born and ground-based experiments have attracted a great deal of interest. These particles represent a unique probe for studying local comic-ray accelerators because they lose energy very rapidly. These energy losses reduce the lifetime so drastically that high-energy cosmic-ray electrons can attain the Earth only from rather local astrophysical sources. This work aims at calculating, by means of Monte Carlo simulation, the contribution from some known nearby astrophysical sources to the cosmic-ray electron/positron spectra at high energy (≥ 10 GeV). The background to the electron energy spectrum from distant sources is determined with the help of the GALPROP code. The obtained numerical results are compared with a set of experimental data.

  12. Study on the test of transient ultraviolet spectrum for remote extended area sources with spectrometer

    NASA Astrophysics Data System (ADS)

    Li, Hongguang; Yang, Hongru; Wu, Baoning; Chang, Weijun; Bai, Zhao; Yin, Qingyan

    2010-10-01

    Spectral radiation intensity measurement at ultraviolet wavelengths is important for the material composition analysis of transient extended area light sources. Here we developed transient ultraviolet multi-spectral spectrometer which is utilized to measure relative spectral radiation intensity distributions of remote transient as well as steady-state extended area light sources in the wavelength range (0.22-0.40) μm. Simultaneously the device also shows different spectral radiation intensity distribution curve of the transient radiation source along with time changes. This spectrometer consists of mobile collimation lens, Cassegrain imaging system, grating spectrograph, high speed data acquisition system and computer software. Since ultraviolet spectral radiation is severely absorbed in air transmission, firstly the Cassegrain system which has high reflectance in ultraviolet wavelength range is used to image the extended area light source onto the entrance slit of spectrograph, in order to markedly improve the light gathering power of the device. The spectrograph uses plane blazed grating to disperse spectrums which are focalized as the focal plane for detection by ultraviolet response enhancing array CCD detector. Secondly, to resolve spectrum acquisition problem of nanosecond transient light sources, we adopt CCD drive technology programmed by CPLD and fixed phasic high speed data acquisition method. Finally, the spectral distortion of the spectrograph is reduced by using non-parametric kernel regression de-noising algorithm and convolution algorithm in order to improve the spectral resolving power of the device. So we experimentalize for spectral radiation intensity distributions of remote transient and steady-state extended area light sources, then the uncertainty of measurement results is analyzed.

  13. DETECTORS AND EXPERIMENTAL METHODS: Measurement of the neutron spectrum of a Pu-C source with a liquid scintillator

    NASA Astrophysics Data System (ADS)

    Wang, Song-Lin; Huang, Han-Xiong; Ruan, Xi-Chao; Li, Xia; Bao, Jie; Nie, Yang-Bo; Zhong, Qi-Ping; Zhou, Zu-Ying; Kong, Xiang-Zhong

    2009-05-01

    The neutron response function for a BC501A liquid scintillator (LS) has been measured using a series of monoenergetic neutrons produced by the p-T reaction. The proton energies were chosen such as to produce neutrons in the energy range of 1 to 20 MeV. The principles of the technique of unfolding a neutron energy spectrum by using the measured neutron response function and the measured Pulse Height (PH) spectrum is briefly described. The PH spectrum of neutrons from the Pu-C source, which will be used for the calibration of the reactor antineutrino detectors for the Daya Bay neutrino experiment, was measured and analyzed to get the neutron energy spectrum. Simultaneously the neutron energy spectrum of an Am-Be source was measured and compared with other measurements as a check of the result for the Pu-C source. Finally, an error analysis and a discussion of the results are given.

  14. Measuring the activity of a {sup 51}Cr neutrino source based on the gamma-radiation spectrum

    SciTech Connect

    Gorbachev, V. V. Gavrin, V. N.; Ibragimova, T. V.; Kalikhov, A. V.; Malyshkin, Yu. M.; Shikhin, A. A.

    2015-12-15

    A technique for the measurement of activities of intense β sources by measuring the continuous gamma-radiation (internal bremsstrahlung) spectra is developed. A method for reconstructing the spectrum recorded by a germanium semiconductor detector is described. A method for the absolute measurement of the internal bremsstrahlung spectrum of {sup 51}Cr is presented.

  15. Flat-spectrum radio source C1 in M33 is a background radio galaxy

    SciTech Connect

    Reynolds, S.P.; Fix, J.D.

    1988-10-01

    A candidate Crab-like supernova remnant in M33 discovered in a high-resolution survey of compact radio sources (Reynolds and Fix, 1987) has been observed. VLA observations at 1465 and 4885 MHz show that it is simply the flat-spectrum core of a completely normal double-lobed radio galaxy. This eliminates the last candidate Crab-like object in M33 whose size and brightness do not at all resemble those of the Crab Nebula, and confirms the dearth of Crab-like supernova remnants reported earlier. 7 references.

  16. Effect of photon energy spectrum on dosimetric parameters of brachytherapy sources

    PubMed Central

    Ghorbani, Mahdi; Davenport, David

    2016-01-01

    Abstract Aim The aim of this study is to quantify the influence of the photon energy spectrum of brachytherapy sources on task group No. 43 (TG-43) dosimetric parameters. Background Different photon spectra are used for a specific radionuclide in Monte Carlo simulations of brachytherapy sources. Materials and methods MCNPX code was used to simulate 125I, 103Pd, 169Yb, and 192Ir brachytherapy sources. Air kerma strength per activity, dose rate constant, radial dose function, and two dimensional (2D) anisotropy functions were calculated and isodose curves were plotted for three different photon energy spectra. The references for photon energy spectra were: published papers, Lawrence Berkeley National Laboratory (LBNL), and National Nuclear Data Center (NNDC). The data calculated by these photon energy spectra were compared. Results Dose rate constant values showed a maximum difference of 24.07% for 103Pd source with different photon energy spectra. Radial dose function values based on different spectra were relatively the same. 2D anisotropy function values showed minor differences in most of distances and angles. There was not any detectable difference between the isodose contours. Conclusions Dosimetric parameters obtained with different photon spectra were relatively the same, however it is suggested that more accurate and updated photon energy spectra be used in Monte Carlo simulations. This would allow for calculation of reliable dosimetric data for source modeling and calculation in brachytherapy treatment planning systems. PMID:27247558

  17. CRATES: An All-Sky Survey of Flat-Spectrum Radio Sources

    SciTech Connect

    Healey, Stephen E.; Romani, Roger W.; Taylor, Gregory B.; Sadler, Elaine M.; Ricci, Roberto; Murphy, Tara; Ulvestad, James S.; Winn, Joshua N.; /MIT

    2007-02-20

    We have assembled an 8.4 GHz survey of bright, flat-spectrum ({alpha} > -0.5) radio sources with nearly uniform extragalactic (|b| > 10{sup o}) coverage for sources brighter than S{sub 4.8 GHz} = 65 mJy. The catalog is assembled from existing observations (especially CLASS and the Wright et al. PMN-CA survey), augmented by reprocessing of archival VLA and ATCA data and by new observations to fill in coverage gaps. We refer to this program as CRATES, the Combined Radio All-sky Targeted Eight GHz Survey. The resulting catalog provides precise positions, sub-arcsecond structures, and spectral indices for some 11,000 sources. We describe the morphology and spectral index distribution of the sample and comment on the survey's power to select several classes of interesting sources, especially high energy blazars. Comparison of CRATES with other high-frequency surveys also provides unique opportunities for identification of high-power radio sources.

  18. Initial study of the optical spectrum of the ISIS H{sup -} ion source plasma

    SciTech Connect

    Lawrie, S. R.; Faircloth, D. C.; Philippe, K.

    2012-02-15

    The front end test stand is being constructed at the Rutherford Appleton Laboratory, with the aim of producing a 60 mA, 2 ms, 50 Hz, perfectly chopped H{sup -} ion beam. To meet the beam requirements, a more detailed understanding of the ion source plasma is required. To this end, an initial study is made of the optical spectrum of the plasma using a digital spectrometer. The atomic and molecular emission lines of hydrogen and caesium are clearly distinguished and a quantitative comparison is made when the ion source is run in different conditions. The electron temperature is 0.6 eV and measured line widths vary by up to 75%.

  19. Initial study of the optical spectrum of the ISIS H- ion source plasma.

    PubMed

    Lawrie, S R; Faircloth, D C; Philippe, K

    2012-02-01

    The front end test stand is being constructed at the Rutherford Appleton Laboratory, with the aim of producing a 60 mA, 2 ms, 50 Hz, perfectly chopped H(-) ion beam. To meet the beam requirements, a more detailed understanding of the ion source plasma is required. To this end, an initial study is made of the optical spectrum of the plasma using a digital spectrometer. The atomic and molecular emission lines of hydrogen and caesium are clearly distinguished and a quantitative comparison is made when the ion source is run in different conditions. The electron temperature is 0.6 eV and measured line widths vary by up to 75%.

  20. [DWT-iPLS applied in the infrared diffuse reflection spectrum of hydrocarbon source rocks].

    PubMed

    Song, Ning; Xu, Xiao-xuan; Wu, Zhong-chen; Zhang, Cun-zhou; Wang, Bin

    2008-08-01

    Infrared spectroscopy is useful to monitor the quality of products on-line, or to quality multivariate properties simultaneously. The IR spectrometer satisfies the requirements of users who want to have quantitative product information in real-time because the instrument provides the information promptly and easily. However, Samples that are measured using diffuse reflectance often exhibit significant differences in the spectra due to the non-homogeneous distribution of the particles. In fact, multiple spectral measurements of the same sample can look completely different. In many cases, the scattering can be an overpowering contributor to the spectrum, sometimes accounting for most of the variance in the data. Although the degree of scattering is dependent on the wavelength of the light that is used and the particle size and refractive index of the sample, the scattering is not uniform throughout the spectrum. Typically, this appears as a baseline shift, tilt and sometimes curvature, where the degree of influence is more pronounced at the longer-wavelength end of the spectrum. The diffuse reflection spectrum is unsatisfactory and the calibration may provide unsatisfactory prediction results. So we must use some methods to remove the effects of the scattering for multivariate calibration of IR spectral signals. Discrete wavelet transform (DWT) is a good method to remove the effects of the scattering for multivariate calibration of IR spectral signals. By using DWT on individual signals as a preprocessing method in regression modeling on IR spectra, good compression is achieved with almost no loss of information, the low-frequency varying background and the high-frequency noise be removed simultaneously. In this report, we use the iPLS method to establish the calibration models of hydrocarbon source rocks. iPLS is a new regression method and the authors can get better results by using DTW- iPLS.

  1. Percent Agricultural Land Cover on Steep Slopes

    EPA Pesticide Factsheets

    Clearing land for agriculture tends to increase soil erosion. The amount of erosion is related to the steepness of the slope, farming methods used and soil type. High amounts of agriculture on steep slopes can increase the amount of soil erosion leading to increased sediment in surface water. Agricultural land cover on steep slopes (AGSL) is the percent of agriculture on slopes greater than or equal to 9%. More information about these resources, including the variables used in this study, may be found here: https://edg.epa.gov/data/Public/ORD/NERL/ReVA/ReVA_Data.zip.

  2. DISCOVERY OF THE HARD SPECTRUM VHE γ-RAY SOURCE HESS J1641–463

    SciTech Connect

    Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Bernlöhr, K.; Akhperjanian, A. G.; Angüner, E. O.; Birsin, E.; Backes, M.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Biteau, J.; Boisson, C. E-mail: sabrina.casanova@mpi-hd.mpg.de; Collaboration: H.E.S.S. Collaboration; and others

    2014-10-10

    This Letter reports the discovery of a remarkably hard spectrum source, HESS J1641–463, by the High Energy Stereoscopic System (H.E.S.S.) in the very high energy (VHE) domain. HESS J1641–463 remained unnoticed by the usual analysis techniques due to confusion with the bright nearby source HESS J1640–465. It emerged at a significance level of 8.5 standard deviations after restricting the analysis to events with energies above 4 TeV. It shows a moderate flux level of φ(E>1 TeV) = (3.64 ± 0.44{sub stat} ± 0.73{sub sys}) × 10{sup –13} cm{sup –2} s{sup –1}, corresponding to 1.8% of the Crab Nebula flux above the same energy, and a hard spectrum with a photon index of Γ = 2.07 ± 0.11{sub stat} ± 0.20{sub sys}. It is a point-like source, although an extension up to a Gaussian width of σ = 3 arcmin cannot be discounted due to uncertainties in the H.E.S.S. point-spread function. The VHE γ-ray flux of HESS J1641–463 is found to be constant over the observed period when checking time binnings from the year-by-year to the 28 minute exposure timescales. HESS J1641–463 is positionally coincident with the radio supernova remnant SNR G338.5+0.1. No X-ray candidate stands out as a clear association; however, Chandra and XMM-Newton data reveal some potential weak counterparts. Various VHE γ-ray production scenarios are discussed. If the emission from HESS J1641–463 is produced by cosmic ray protons colliding with the ambient gas, then their spectrum must extend close to 1 PeV. This object may represent a source population contributing significantly to the galactic cosmic ray flux around the knee.

  3. OPTICAL SPECTRA OF CANDIDATE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) FLAT-SPECTRUM RADIO SOURCES

    SciTech Connect

    Titov, O.; Stanford, Laura M.; Johnston, Helen M.; Hunstead, Richard W.; Pursimo, T.; Jauncey, David L.; Maslennikov, K.

    2013-07-01

    Continuing our program of spectroscopic observations of International Celestial Reference Frame (ICRF) sources, we present redshifts for 120 quasars and radio galaxies. Data were obtained with five telescopes: the 3.58 m European Southern Observatory New Technology Telescope, the two 8.2 m Gemini telescopes, the 2.5 m Nordic Optical Telescope (NOT), and the 6.0 m Big Azimuthal Telescope of the Special Astrophysical Observatory in Russia. The targets were selected from the International VLBI Service for Geodesy and Astrometry candidate International Celestial Reference Catalog which forms part of an observational very long baseline interferometry (VLBI) program to strengthen the celestial reference frame. We obtained spectra of the potential optical counterparts of more than 150 compact flat-spectrum radio sources, and measured redshifts of 120 emission-line objects, together with 19 BL Lac objects. These identifications add significantly to the precise radio-optical frame tie to be undertaken by Gaia, due to be launched in 2013, and to the existing data available for analyzing source proper motions over the celestial sphere. We show that the distribution of redshifts for ICRF sources is consistent with the much larger sample drawn from Faint Images of the Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying that the ultra-compact VLBI sources are not distinguished from the overall radio-loud quasar population. In addition, we obtained NOT spectra for five radio sources from the FIRST and NRAO VLA Sky Survey catalogs, selected on the basis of their red colors, which yielded three quasars with z > 4.

  4. Recognition Memory, Self-Other Source Memory, and Theory-of-Mind in Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Lind, Sophie E.; Bowler, Dermot M.

    2009-01-01

    This study investigated semantic and episodic memory in autism spectrum disorder (ASD), using a task which assessed recognition and self-other source memory. Children with ASD showed undiminished recognition memory but significantly diminished source memory, relative to age- and verbal ability-matched comparison children. Both children with and…

  5. Brief Report: The Role of Task Support in the Spatial and Temporal Source Memory of Adults with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Bowler, Dermot M.; Gaigg, Sebastian B.; Gardiner, John M.

    2015-01-01

    Adults with autism spectrum disorder (ASD) show intact recognition (supported procedure) but impaired recall (unsupported procedure) of incidentally-encoded context. Because this has not been demonstrated for temporal source, we compared the temporal and spatial source memory of adults with ASD and verbally matched typical adults. Because of…

  6. Spectrum and anisotropy of cosmic rays at TeV-PeV-energies and contribution of nearby sources

    NASA Astrophysics Data System (ADS)

    Sveshnikova, L. G.; Strelnikova, O. N.; Ptuskin, V. S.

    2013-12-01

    The role of nearby galactic sources, the supernova remnants, in formation of observed energy spectrum and large-scale anisotropy of high-energy cosmic rays is studied. The list of these sources is made up based on radio, X-ray and gamma-ray catalogues. The distant sources are treated statistically as ensemble of sources with random positions and ages. The source spectra are defined based on the modern theory of cosmic ray acceleration in supernova remnants while the propagation of cosmic rays in the interstellar medium is described in the frameworks of galactic diffusion model. Calculations of dipole component of anisotropy are made to reproduce the experimental procedure of "two-dimensional" anisotropy measurements. The energy dependence of particle escape time in the process of acceleration in supernova remnants and the arm structure of sources defining the significant features of anisotropy are also taken into account. The essential new trait of the model is a decreasing number of core collapse SNRs being able to accelerate cosmic rays up to the given energy, that leads to steeper total cosmic ray source spectrum in comparison with the individual source spectrum. We explained simultaneously the new cosmic ray data on the fine structure of all particle spectrum around the knee and the amplitude and direction of the dipole component of anisotropy in the wide energy range 1 TeV-1 EeV. Suggested assumptions do not look exotic, and they confirm the modern understanding of cosmic ray origin.

  7. Diesel engine noise source identification based on EEMD, coherent power spectrum analysis and improved AHP

    NASA Astrophysics Data System (ADS)

    Zhang, Junhong; Wang, Jian; Lin, Jiewei; Bi, Fengrong; Guo, Qian; Chen, Kongwu; Ma, Liang

    2015-09-01

    As the essential foundation of noise reduction, many noise source identification methods have been developed and applied to engineering practice. To identify the noise source in the board-band frequency of different engine parts at various typical speeds, this paper presents an integrated noise source identification method based on the ensemble empirical mode decomposition (EEMD), the coherent power spectrum analysis, and the improved analytic hierarchy process (AHP). The measured noise is decomposed into several IMFs with physical meaning, which ensures the coherence analysis of the IMFs and the vibration signals are meaningful. An improved AHP is developed by introducing an objective weighting function to replace the traditional subjective evaluation, which makes the results no longer dependent on the subject performances and provides a better consistency in the meantime. The proposed noise identification model is applied to identifying a diesel engine surface radiated noise. As a result, the frequency-dependent contributions of different engine parts to different test points at different speeds are obtained, and an overall weight order is obtained as oil pan  >  left body  >  valve chamber cover  >  gear chamber casing  >  right body  >  flywheel housing, which provides an effectual guidance for the noise reduction.

  8. Aerogel Cherenkov detector for characterizing the intense flash x-ray source, Cygnus, spectrum

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Herrmann, H. W.; McEvoy, A. M.; Young, C. S.; Hamilton, C.; Schwellenbach, D. D.; Malone, R. M.; Kaufman, M. I.; Smith, A. S.

    2016-11-01

    An aerogel Cherenkov detector is proposed to measure the X-ray energy spectrum from the Cygnus—intense flash X-ray source operated at the Nevada National Security Site. An array of aerogels set at a variety of thresholds between 1 and 3 MeV will be adequate to map out the bremsstrahlung X-ray production of the Cygnus, where the maximum energy of the spectrum is normally around 2.5 MeV. In addition to the Cherenkov radiation from aerogels, one possible competing light-production mechanism is optical transition radiation (OTR), which may be significant in aerogels due to the large number of transitions from SiO2 clusters to vacuum voids. To examine whether OTR is a problem, four aerogel samples were tested using a mono-energetic electron beam (varied in the range of 1-3 MeV) at NSTec Los Alamos Operations. It was demonstrated that aerogels can be used as a Cherenkov medium, where the rate of the light production is about two orders magnitude higher when the electron beam energy is above threshold.

  9. The 4-8 micron spectrum of the infrared source W33 A

    NASA Technical Reports Server (NTRS)

    Soifer, B. T.; Puetter, R. C.; Russell, R. W.; Willner, S. P.; Harvey, P. M.; Gillett, F. C.

    1979-01-01

    The spectrum of the highly obscured infrared source W33 A from 4.5 to 8 microns is measured in order to investigate the intervening cold, dense interstellar material. Spectrophotometry at a relative spectral resolution of about 0.015 by an airborne filter-wheel infrared spectrometer reveals strong absorption features at 4.61, 5.99 and 6.78 microns. The absorption at 4.61 microns is attributed primarily to the fundamental vibration-rotation band of CO at a column density (at least 10 to the 19th/sq cm) which is 10% of the carbon inferred from silicate abundances. The strengths and line widths of the absorption agt 5.99 and 6.78 microns are interpreted as evidence of absorption in the resonance bands of carbonyl, carbon-carbon double, methyl and methylene bonds of hydrocarbons associated with interstellar dust.

  10. White LEDs as broad spectrum light sources for spectrophotometry: demonstration in the visible spectrum range in a diode-array spectrophotometric detector.

    PubMed

    Piasecki, Tomasz; Breadmore, Michael C; Macka, Mirek

    2010-11-01

    Although traditional lamps, such as deuterium lamps, are suitable for bench-top instrumentation, their compatibility with the requirements of modern miniaturized instrumentation is limited. This study investigates the option of utilizing solid-state light source technology, namely white LEDs, as a broad band spectrum source for spectrophotometry. Several white light LEDs of both RGB and white phosphorus have been characterized in terms of their emission spectra and energy output and a white phosphorus Luxeon LED was then chosen for demonstration as a light source for visible-spectrum spectrophotometry conducted in CE. The Luxeon LED was fixed onto the base of a dismounted deuterium (D(2) ) lamp so that the light-emitting spot was geometrically positioned exactly where the light-emitting spot of the original D(2) lamp is placed. In this manner, the detector of a commercial CE instrument equipped with a DAD was not modified in any way. As the detector hardware and electronics remained the same, the change of the deuterium lamp for the Luxeon white LED allowed a direct comparison of their performances. Several anionic dyes as model analytes with absorption maxima between 450 and 600 nm were separated by CE in an electrolyte of 0.01 mol/L sodium tetraborate. The absorbance baseline noise as the key parameter was 5 × lower for the white LED lamp, showing clearly superior performance to the deuterium lamp in the available, i.e. visible part of the spectrum.

  11. Obscured flat spectrum radio active galactic nuclei as sources of high-energy neutrinos

    NASA Astrophysics Data System (ADS)

    Maggi, G.; Buitink, S.; Correa, P.; de Vries, K. D.; Gentile, G.; Tavares, J. León; Scholten, O.; van Eijndhoven, N.; Vereecken, M.; Winchen, T.

    2016-11-01

    Active galactic nuclei (AGN) are believed to be one of the main source candidates for the high-energy (TeV-PeV) cosmic neutrino flux recently discovered by the IceCube neutrino observatory. Nevertheless, several correlation studies between AGN and the cosmic neutrinos detected by IceCube show no significance. Therefore, in this article we consider a specific subclass of AGN for which an increased neutrino production is expected. This subclass contains AGN for which their high-energy jet is pointing toward Earth. Furthermore, we impose the condition that the jet is obscured by gas or dust surrounding the AGN. A method is presented to determine the total column density of the obscuring medium, which is probed by determining the relative x-ray attenuation with respect to the radio flux as obtained from the AGN spectrum. The total column density allows us to probe the interaction of the jet with the surrounding matter, which leads to additional neutrino production. Finally, starting from two different source catalogs, this method is applied to specify a sample of low redshift radio galaxies for which an increased neutrino production is expected.

  12. On the relation between steep monoclinal flexure zones and steep hydraulic gradients.

    PubMed

    Yechieli, Y; Kafri, U; Wollman, S; Lyakhovsky, V; Weinberger, R

    2007-01-01

    Steep hydraulic gradients are found in association with steep monoclinal flexures. However, the physics of the reduction of the hydraulic conductivity, which is responsible for the steep gradients, has seldom been studied. We present results of hydrological and mechanical modeling aiming to study the effect of such steep hydraulic gradients demonstrated in the Judea Group Aquifer system, Israel. The hydrological configuration of steep dips and anisotropy between flows parallel and perpendicular to the bedding planes was simulated using the FEFLOW code. It exhibited a situation whereby part of the flow is oblique to the bedding planes and therefore some steepening of the hydraulic gradients occurred due to actual conductivity reduction. However, this reduction is not enough to account for the steeper gradients observed. The effect of a deep-seated reverse fault under the monocline on the permeability distribution within the structure was examined by numerical mechanical simulations. It exhibited a compressional stress distribution in the steep part of the monocline, which, due to shortening and closure of joints and voids, is presumably responsible for a significant pressure-induced permeability reduction. This process by itself in a layered structure, including interlayering of thin marl layers, could be responsible for the steep hydraulic gradients in the steep part of the monocline.

  13. Evolution of and High-Energy Emission from GHz-Peaked Spectrum Sources

    NASA Astrophysics Data System (ADS)

    Stawarz, Ł.; Ostorero, L.; Begelman, M. C.; Moderski, R.; Kataoka, J.; Wagner, S.

    2008-06-01

    Here we discuss evolution and broadband emission of compact (sources. We propose a simple dynamical description for these objects, consisting of a relativistic jet propagating into a uniform gaseous medium in the central parts of an elliptical host. In the framework of the proposed model we follow the evolution of ultrarelativistic electrons injected from a terminal hot spot of a jet to expanding lobes, taking into account their adiabatic energy losses, as well as radiative cooling. This allows us to discuss the broadband lobe emission of young radio sources. In particular, we argue that the observed spectral turnover in the radio synchrotron spectra of these objects cannot originate from the synchrotron self-absorption process but is most likely due to free-free absorption effects connected with neutral clouds of interstellar medium engulfed by the expanding lobes and photoionized by active centers. We also find a relatively strong and complex high-energy emission component produced by inverse Compton upscattering of various surrounding photon fields by the lobes' electrons. We argue that such high-energy radiation is strong enough to account for several observed properties of GHz-peaked spectrum (GPS) radio galaxies at UV and X-ray frequencies. In addition, this emission is expected to extend up to GeV (or possibly even TeV) photon energies and can thus be probed by several modern γ-ray instruments. In particular, we suggest that GPS radio galaxies should constitute a relatively numerous class of extragalactic sources detected by GLAST.

  14. The Galactic Center EGRET Source and the Broad-band Spectrum of SGR A East

    NASA Astrophysics Data System (ADS)

    Fatuzzo, M.; Melia, F.; Yusef-Zadeh, F.; Markoff, S.

    1999-06-01

    High energy (30 MeV - 10 GeV) emission associated with a Galactic Center source has recently been observed by EGRET on board the Compton Gamma-ray Observatory. Continuum low-frequency radio observations of the Galactic Center reveal the presence of several viable source candidates, one of which is a prominent elliptical shell structure known as Sgr A East. Although morphologically similar to supernova remnants (SNRs), its inferred energetics and size appear to be extreme and have generated some uncertainty regarding this interpretation. Additionally, the radio spectral index determined from 6 cm and 20 cm observations of Sgr A East (~ 1) differs from the indices normally found for SNRs (~ 0.5). This difference is quite significant given that the corresponding index for the electron distribution for Sgr A East is then ~3 (versus ~2 for SNRs) and therefore unlike that thought to be produced directly from the shock acceleration processes believed to occur in such an environment. Regardless, recent observations of this region at 1720 MHz (the transition frequency of OH maser emission) have revealed the presence of several maser spots, suggesting a kinship between Sgr A East and three EGRET SNRs also observed at 1720 MHz: IC443, W28 and W44. This possible kinship suggests that Sgr A East could be the source of the EGRET emission. We show here that the pion-production and decay mechanism invoked to account for gamma-ray emission from SNRs can also naturally account for the radio through TeV spectrum of Sgr A East (including the EGRET data). The differences between the spectral features of Sgr A East and the other SNRs then results from the differences between the underlying energetics and the properties of the surrounding interstellar medium.

  15. On the Evolution of and High-Energy Emission from GHz-Peaked-Spectrum Sources

    SciTech Connect

    Stawarz, L.; Ostorero, L.; Begelman, M.C.; Moderski, R.; Kataoka, J.; Wagner, S.

    2007-12-18

    Here we discuss evolution and broad-band emission of compact (< kpc) lobes in young radio sources. We propose a simple dynamical description for these objects, consisting of a relativistic jet propagating into a uniform gaseous medium in the central parts of an elliptical host. In the framework of the proposed model, we follow the evolution of ultrarelativistic electrons injected from a terminal hotspot of a jet to expanding lobes, taking into account their adiabatic energy losses as well as radiative cooling. This allows us to discuss the broad-band lobe emission of young radio sources. In particular, we argue that the observed spectral turnover in the radio synchrotron spectra of these objects cannot originate from the synchrotron self-absorption process but is most likely due to free-free absorption effects connected with neutral clouds of interstellar medium engulfed by the expanding lobes and photoionized by active centers. We also find a relatively strong and complex high-energy emission component produced by inverse-Compton up-scattering of various surrounding photon fields by the lobes electrons. We argue that such high energy radiation is strong enough to account for several observed properties of GHz-peaked-spectrum (GPS) radio galaxies at UV and X-ray frequencies. In addition, this emission is expected to extend up to GeV (or possibly even TeV) photon energies and can thus be probed by several modern {gamma}-ray instruments. In particular, we suggest that GPS radio galaxies should constitute a relatively numerous class of extragalactic sources detected by GLAST.

  16. 30 CFR 816.107 - Backfilling and grading: Steep slopes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Backfilling and grading: Steep slopes. 816.107... ACTIVITIES § 816.107 Backfilling and grading: Steep slopes. (a) Surface mining activities on steep slopes... section except where mining is conducted on flat or gently rolling terrain with an occasional steep...

  17. 30 CFR 816.107 - Backfilling and grading: Steep slopes.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Backfilling and grading: Steep slopes. 816.107... ACTIVITIES § 816.107 Backfilling and grading: Steep slopes. (a) Surface mining activities on steep slopes... section except where mining is conducted on flat or gently rolling terrain with an occasional steep...

  18. Doppler shift measurement of Balmer-alpha line spectrum emission from a plasma in a negative hydrogen ion source

    SciTech Connect

    Wada, M. Doi, K.; Kisaki, M.; Nakano, H.; Tsumori, K.; Nishiura, M.

    2015-04-08

    Balmer-α light emission from the extraction region of the LHD one-third ion source has shown a characteristic Doppler broadening in the wavelength spectrum detected by a high resolution spectrometer. The spectrum resembles Gaussian distribution near the wavelength of the intensity peak, while it has an additional component of a broader foot. The measured broadening near the wavelength of the intensity peak corresponds to 0.6 eV hydrogen atom temperature. The spectrum exhibits a larger expansion in the blue wing which becomes smaller when the line of sight is tilted toward the driver region from the original observation axis parallel to the plasma grid. A surface collision simulation model predicts the possibility of hydrogen reflection at the plasma grid surface to form a broad Balmer-α light emission spectrum.

  19. The design of a source to simulate the gamma-ray spectrum emitted by a radioisotope thermoelectric generator

    NASA Technical Reports Server (NTRS)

    Reier, M.

    1972-01-01

    A simulated source was designed to duplicate the gamma spectrum of a uniform cylindrical 2200-watt Pu02 radioisotope thermoelectric generator containing 81% Pu-238 and 1.2 ppm Pu-236. Gamma rays from the decay of Pu-238, Am-241, Pu-239, and the 0-18(alpha,n)Ne-21 reaction were catalogued in broad energy groups. Two 46- and one 22-mc Th-228 sources provided simulation at various times in the life of the fuel capsule up to 18 years, which covers the time span of an outer planet mission. Emission from Th-228 represents the overwhelming contribution of the gamma spectrum after the first few years. The sources, in the form of 13-inch rods, were placed in a concentric hole in a cylinder of depleted uranium, which provided shielding equivalent to the self-shielding of the fuel capsule. The thickness of the U-238 cylinder (0.55cm) was determined by Monte Carlo calculations to insure that the spectrum emerging from the simulated source matched that of the fuel capsule.

  20. Flat-spectrum radio sources from the Parkes 2.7 GHz survey - A study of a complete sample

    NASA Technical Reports Server (NTRS)

    Savage, Ann; Jauncey, David L.; White, Graeme L.; Peterson, Bruce A.; Peters, W. L.; Gulkis, Samuel

    1990-01-01

    A complete sample, taken from the Parkes 2.7 GHz catalog, of flat-spectrum radio sources with flux densities greater than 0.5 Jy is described. The sample covers all right ascensions and declinations for +10 deg to -45 deg, excluding the Galactic plane, and contains 403 sources. Attention is drawn to the advantages of radio surveys over optical surveys. The survey is used to highlight some selection effects found in optical surveys. How this sample can be used to give information on the early universe is discussed.

  1. 30 CFR 817.107 - Backfilling and grading: Steep slopes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Backfilling and grading: Steep slopes. 817.107 Section 817.107 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... ACTIVITIES § 817.107 Backfilling and grading: Steep slopes. (a) Underground mining activities on steep...

  2. 30 CFR 817.107 - Backfilling and grading: Steep slopes.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Backfilling and grading: Steep slopes. 817.107 Section 817.107 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... ACTIVITIES § 817.107 Backfilling and grading: Steep slopes. (a) Underground mining activities on steep...

  3. Rough and Steep Terrain Lunar Surface Mobility

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian

    2005-01-01

    In the summer of 2004, the NASA Exploration Systems Mission Directorate conducted an open call for projects relevant to human and robotic exploration of the Earth-Moon and Mars systems. A project entitled 'Rough and Steep Terrain Lunar Surface Mobility' was submitted by JPL and accepted by NASA. The principal investigator of this project describes the robotic vehicle being developed for this effort, which includes six 'wheels-on-legs' so that it can roll efficiently on relatively smooth terrain but walk (using locked wheels as footpads) when "the going gets rough".

  4. Cathode luminescence light source for broadband applications in the visible spectrum

    NASA Technical Reports Server (NTRS)

    Foster, John E. (Inventor)

    2007-01-01

    A device and method for generating cathode luminescence is provided. The device and method generate broad spectrum electromagnetic radiation in the visible. A layer of particles, such as quartz or alumina powder, is exposed to electrons in a plasma discharge. Surface excitation of these particles or the generations/excitation of F-center sites give rise to luminescence.

  5. Accurately computing the optical pathlength difference for a michelson interferometer with minimal knowledge of the source spectrum.

    PubMed

    Milman, Mark H

    2005-12-01

    Astrometric measurements using stellar interferometry rely on precise measurement of the central white light fringe to accurately obtain the optical pathlength difference of incoming starlight to the two arms of the interferometer. One standard approach to stellar interferometry uses a channeled spectrum to determine phases at a number of different wavelengths that are then converted to the pathlength delay. When throughput is low these channels are broadened to improve the signal-to-noise ratio. Ultimately the ability to use monochromatic models and algorithms in each of the channels to extract phase becomes problematic and knowledge of the spectrum must be incorporated to achieve the accuracies required of the astrometric measurements. To accomplish this an optimization problem is posed to estimate simultaneously the pathlength delay and spectrum of the source. Moreover, the nature of the parameterization of the spectrum that is introduced circumvents the need to solve directly for these parameters so that the optimization problem reduces to a scalar problem in just the pathlength delay variable. A number of examples are given to show the robustness of the approach.

  6. Tracing the Origins of Coarse Sediment in Steep Mountain Catchments

    NASA Astrophysics Data System (ADS)

    Lukens, C. E.; Riebe, C. S.; Shuster, D. L.; Sklar, L. S.; Beyeler, J. D.

    2011-12-01

    Where does coarse sediment come from? How long does it persist in channels? What can the origins of sediment tell us about erosional processes and particle comminution in hillslope soils and mountain streams? To address these questions, we present new apatite-helium (AHe) ages from coarse sediment in steep streams of the Sierra Nevada, California. The evolution of grain size in sediment reflects both the physical and chemical breakdown of particles as they travel downstream. It also should reflect the dominant mechanisms of landscape evolution within a watershed. Previous studies have exploited detrital thermochronology in tracing the origins of sand-sized particles; the approach uses AHe age distributions in the sand as a geochemical fingerprint that can be compared with age-elevation relationships in bedrock as an indicator of provenance. In steep catchments, however, sand-sized particles comprise only a fraction of the sediment on the bed, and therefore tell only part of the erosional story. Much can be learned by examining age distributions of coarser grain sizes. Source elevations of coarse particles, for instance, may help reveal the relative importance of erosional mechanisms. For example, if boulders are sourced at high elevations, rock fall and debris flows likely dominate their transport. Conversely, if boulders are sourced only at lower elevations (nearer the sample location), they are more likely produced locally, and thus break down in place. We show how hypotheses such as these can be tested using detrital thermochronology on coarse sediment. We show how our analysis of detrital apatite can be coupled with a numerical model of the evolution of grain-size distributions by particle breakdown and input from slopes. We elaborate on how this approach can shed new quantitative light on processes of sediment production, transport, and breakdown in mountainous settings.

  7. Factors Affecting VUV Emission Spectrum near Lyman-{alpha} from a Hydrogen Plasma Source

    SciTech Connect

    Ogino, K.; Kasuya, T.; Shimamoto, S.; Wada, M.; Kimura, Y.; Nishiura, M.

    2011-09-26

    Vacuum ultra violet (VUV) emission spectra from plasmas near walls of different metallic materials were measured to estimate the effect upon the local production rate of vibrational excited hydrogen molecules due to plasma wall interaction. Among Cu, Mo, Ni, Ta and Ti, the intensity of band spectrum around Lyman-{alpha} had become the largest when Cu wall was used while it was the smallest for Ti. The role of particle reflection from the plasma electrode surface upon the H{sup -} production by a pure electron volume process is discussed.

  8. A Method for Determining the High Energy Photon Spectrum of a Pulsed Plasma Source.

    DTIC Science & Technology

    1984-03-01

    detector voltages. The program is to outpjt a spectrum giving photon group enerjies and energy amounts. Data from the coaxial plasma gun is to be...radiated, anA the surface area through which the enerjy is radiatei. If the plasma diameter is 0.5 cm, has a lenjth of 2.0 cm, and a radiation time of...radiated. Evaluating ’equation (,) give3 thi- a iouint Df enerjy between 3, keV andl . infinity that passes t’iroujh the vacuum chamber as being 6.,R x 10 e

  9. Relevance of aerosol size spectrum analysis as support to qualitative source apportionment studies.

    PubMed

    Manigrasso, M; Febo, A; Guglielmi, F; Ciambottini, V; Avino, P

    2012-11-01

    This work presents a diagnostic methodology in support to source apportionment studies to identify remote and local pollution sources. It is based on the temporal analysis of both PM size distributions and PM size fraction correlation along with natural radioactivity measurements as index of Planetary Boundary Layer dynamic. A correlation drop is indicative of changing aerosol sources. When this observation is coupled with decreasing level of natural radioactivity and increasing aerosol concentration, be it coarse or fine, it is indicative of the inflow of remote polluted air masses. The methodology defines in which size range operates the contribution of remote pollution sources. It was applied to two PM10 pollution episodes: the first involved the advection of coarse PM, the second entailed the inflow of two air masses, one transporting coarse dust and the other fine PM. Dust models and backward trajectories analysis confirmed such results, indicating the air mass provenience.

  10. On the nature of bright compact radio sources at z > 4.5

    NASA Astrophysics Data System (ADS)

    Coppejans, Rocco; Frey, Sándor; Cseh, Dávid; Müller, Cornelia; Paragi, Zsolt; Falcke, Heino; Gabányi, Krisztina É.; Gurvits, Leonid I.; An, Tao; Titov, Oleg

    2016-12-01

    High-redshift radio-loud quasars are used to, among other things, test the predictions of cosmological models, set constraints on black hole growth in the early Universe and understand galaxy evolution. Prior to this paper, 20 extragalactic radio sources at redshifts above 4.5 have been imaged with very long baseline interferometry (VLBI). Here, we report on observations of an additional ten z > 4.5 sources at 1.7 and 5 GHz with the European VLBI Network, thereby increasing the number of imaged sources by 50 per cent. Combining our newly observed sources with those from the literature, we create a substantial sample of 30 z > 4.5 VLBI sources, allowing us to study the nature of these objects. Using spectral indices, variability and brightness temperatures, we conclude that of the 27 sources with sufficient information to classify, the radio emission from one source is from star formation, 13 are flat-spectrum radio quasars and 13 are steep-spectrum sources. We also argue that the steep-spectrum sources are off-axis (unbeamed) radio sources with rest-frame self-absorption peaks at or below GHz frequencies and that these sources can be classified as gigahertz peaked-spectrum and megahertz peaked-spectrum sources.

  11. Recognition memory and source memory in autism spectrum disorder: A study of the intention superiority and enactment effects.

    PubMed

    Grainger, Catherine; Williams, David M; Lind, Sophie E

    2016-06-22

    It is well established that neurotypical individuals generally show better memory for actions they have performed than actions they have observed others perform or merely read about, a so-called 'enactment effect'. Strikingly, research has also shown that neurotypical individuals demonstrate superior memory for actions they intend to perform in the future (but have not yet performed), an effect commonly known as the 'intention superiority effect'. Although the enactment effect has been studied among people with autism spectrum disorder, this study is the first to investigate the intention superiority effect in this disorder. This is surprising given the potential importance this issue has for general theory development, as well as for clinical practice. As such, this study aimed to assess the intention superiority and enactment effects in 22 children with autism spectrum disorder, and 20 intelligence quotient/age-matched neurotypical children. The results showed that children with autism spectrum disorder demonstrated not only undiminished enactment effects in recognition and source memory, but also (surprisingly for some theories) typical intention superiority effects. The implications of these results for theory, as well as clinical practice, are discussed.

  12. Cylindrical angular spectrum using Fourier coefficients of point light source and its application to fast hologram calculation.

    PubMed

    Oh, Seungtaik; Jeong, Il Kwon

    2015-11-16

    We will introduce a new simple analytic formula of the Fourier coefficient of the 3D field distribution of a point light source to generate a cylindrical angular spectrum which captures the object wave in 360° in the 3D Fourier space. Conceptually, the cylindrical angular spectrum can be understood as a cylindrical version of the omnidirectional spectral approach of Sando et al. Our Fourier coefficient formula is based on an intuitive observation that a point light radiates uniformly in all directions. Our formula is defined over all frequency vectors lying on the entire sphere in the 3D Fourier space and is more natural and computationally more efficient for all around recording of the object wave than that of the previous omnidirectional spectral method. A generalized frequency-based occlusion culling method for an arbitrary complex object is also proposed to enhance the 3D quality of a hologram. As a practical application of the cylindrical angular spectrum, an interactive hologram example is presented together with implementation details.

  13. Identifying a Damped Lyman Alpha Source in the Spectrum of Quasar SDSS J233544.18+150118.3

    NASA Astrophysics Data System (ADS)

    Browning, Benjamin; Takamiya, Marianne Y.; Chun, Mark Richard; Kulkarni, Varsha P.; Gharanfoli, Soheila

    2014-06-01

    We present the nebular properties of a DLA along the line-of-sight of the quasar SDSS J233544.18+150118.3. We obtained two IFU spectra with UH 2.2m/SNIFS approximately 4 arcseconds south of the quasar. A careful analysis of the sky spectra surrounding the DLA then allowed us to generate a high SNR sky spectrum. Through a close examination of our reduced images, we have successfully identified a faint but distinct source of [OII] emission at the same redshift reported elsewhere for the damped Lyman-Alpha absorption lines in the quasar's spectrum. Further investigation also revealed the presence of lower intensity H-beta emission lines at the same redshift. Based on the relative intensities of the [OII] and H-beta lines in the spectrum of this relatively dim intervening galaxy, we present some initial conclusions regarding nebular abundance and star formation rate in this newly identified galaxy, and how its properties compare with a representative sample of galaxies at similar redshifts and luminosities.

  14. Effect of source spectrum on sound localization in an everyday reverberant room

    PubMed Central

    Ihlefeld, Antje; Shinn-Cunningham, Barbara G.

    2011-01-01

    Two experiments explored how frequency content impacts sound localization for sounds containing reverberant energy. Virtual sound sources from thirteen lateral angles and four distances were simulated in the frontal horizontal plane using binaural room impulse responses measured in an everyday office. Experiment 1 compared localization judgments for one-octave-wide noise centered at either 750 Hz (low) or 6000 Hz (high). For both band-limited noises, perceived lateral angle varied monotonically with source angle. For frontal sources, perceived locations were similar for low- and high-frequency noise; however, for lateral sources, localization was less accurate for low-frequency noise than for high-frequency noise. With increasing source distance, judgments of both noises became more biased toward the median plane, an effect that was greater for low-frequency noise than for high-frequency noise. In Experiment 2, simultaneous presentation of low- and high-frequency noises yielded performance that was less accurate than that for high-frequency noise, but equal to or better than for low-frequency noise. Results suggest that listeners perceptually weight low-frequency information heavily, even in reverberant conditions where high-frequency stimuli are localized more accurately. These findings show that listeners do not always optimally adjust how localization cues are integrated over frequency in reverberant settings. PMID:21786902

  15. Ionized gas in the Irr galaxy IC 10: The emission spectrum and ionization sources

    NASA Astrophysics Data System (ADS)

    Arkhipova, V. P.; Egorov, O. V.; Lozinskaya, T. A.; Moiseev, A. V.

    2011-02-01

    We present the observations of the Irr galaxy IC 10 at the 6-m SAO telescope with the panoramic Multi-Pupil Fiber Spectrograph (MPFS). Based on the results of these observations and our long-slit spectroscopy performed previously, we have investigated the ionized-gas emission spectrum in the region of intense star formation and refined the gas metallicity estimates. We show that the “diagnostic diagrams” constructed from our observations agree best with the new improved ionization models by Martin-Manjon et al. Using these models, we have determined the electron density and gas ionization parameter and ionizing-cluster characteristics, the age and mass, from the spectra of the investigated HII regions. The cluster ages and masses are shown to be within the ranges 2.5-5 Myr and (0.2-1) × 105 M ⊗, respectively.

  16. Balmer-α spectrum measurements of the LHD one-third ion source

    SciTech Connect

    Wada, M.; Kenmotsu, T.; Kisaki, M.; Nakano, H.; Tsumori, K.; Nishiura, M.

    2016-02-15

    Wavelength spectra of Balmer-α light from plasmas in the extraction region of the Large Helical Device-R&D negative ion source, or the LHD one-third ion source have exhibited a blue shift as a negative bias voltage was applied to the plasma grid. The blue shift increased as the negative bias voltage with respect to the local plasma potential was increased. The measured spectra were compared with the velocity distributions of surface reflected hydrogen atoms calculated by atomic collisions in amorphous target code. The arc power and the source H{sub 2} pressure also affected the shift and broadening in the observed Balmer-α spectra. The possibility of identifying the negative hydrogen ions produced at the low work function plasma grid surface by high resolution spectroscopy is discussed.

  17. Preferential Transport of Coarse Sediment in Steep Channels

    NASA Astrophysics Data System (ADS)

    Moody, J. A.

    2002-12-01

    Wildfires can change a source-limited system to a transport-limited system especially in steep mountainous terrain where the erosion threshold has been lowered by a wildfire. Such a situation occurred in the Buffalo and Spring Creek watersheds after the 1996 Buffalo Creek Fire, when 1 to 3 m of sediment was deposited in two relatively steep main channels (channel slope equal to 0.02 and 0.04 respectively) after an intense rainstorm of about 110 mm/hour. The bed material was a mixture of coarse grain sizes in both channels. The median size class in Buffalo Creek was 2-4 mm and in Spring Creek it was 4-8 mm. Bedload transport samples were collected in the field using a US BLH-84 sampler for discharge ranging from 0.0036 to 5.2 m3/s. The particle-size distributions for the bedload samples were analyzed to investigate sediment mobility. For each size class, a ratio was calculated equal to the percent of sediment transported divided by the percent of sediment available for transport. The percent available for transport was determined by recalculating the particle-size distribution of the bed material by excluding those sizes that did not move. The average ratio for the median-size class was 1.00 (13 samples) for Buffalo Creek and 0.94 (12 samples) for Spring Creek. In the Buffalo Creek channel, the average ratio for sizes larger than the median size (greater than 2-4 mm) was less than 1.00. Whereas in the Spring Creek channel, the data indicate a preferential transport of sizes larger than the median size with the ratio ranging from 0.86 to 2.22 and averaging 1.42 for the 8-16 mm size class and from 0.37 to 3.86 and averaging 1.28 for the 16-32 mm size class. Possible causes for the difference between Buffalo and Spring Creeks are: 1) the smaller value of the relative roughness (particle diameter/flow depth) in Buffalo Creek, 2) the less steep bed slope in Buffalo Creek, and 3) the difference in the sediment-size distribution

  18. Novel, High-power, Mid-infrared Optical Source for the 5-12 Micron Spectrum

    DTIC Science & Technology

    2011-12-01

    mid‐IR nonlinear crystals of MgO:PPLN, MgO:sPPLT, and CdSiP2 together with  fiber  and solid‐ state  laser  technology at  1064  nm as the pump source...power scaling, we deployed cw Yb fiber laser technology at 1064 nm as the primary laser pump source. In our early effort in this direction, we...phase-matched (QPM) nonlinear material, MgO:PPLN, as the gain medium [1]. Using a single-frequency, cw Yb fiber laser at 1064 nm and a 50-mm-long

  19. ANOMALOUSLY STEEP REDDENING LAW IN QUASARS: AN EXCEPTIONAL EXAMPLE OBSERVED IN IRAS 14026+4341

    SciTech Connect

    Jiang Peng; Zhou Hongyan; Ji Tuo; Shu Xinwen; Liu Wenjuan; Dong Xiaobo; Wang Huiyuan; Wang Tinggui; Wang Jianguo

    2013-06-15

    A fraction of the heavily reddened quasars require a reddening curve that is even steeper than that of the Small Magellanic Cloud. In this paper, we thoroughly characterize the anomalously steep reddening law in quasars via an exceptional example observed in IRAS 14026+4341. By comparing the observed spectrum to the quasar composite spectrum, we derive a reddening curve in the rest-frame wavelength range of 1200-10000 A. It has a steep rise at wavelengths shorter than 3000 A, but no significant reddening at longer wavelengths. The absence of dust reddening in the optical continuum is confirmed by the normal broad-line Balmer decrement (the H{alpha}/H{beta} ratio) in IRAS 14026+4341. The anomalous reddening curve can be satisfactorily reproduced with a dust model containing silicate grains in a power-law size distribution, dn(a)/da{proportional_to}a {sup -1.4}, truncated at a maximum size of a{sub max} = 70 nm. The unusual size distribution may be caused by the destruction of large 'stardust' grains by quasar activities or a different dust formation mechanism (i.e., the in situ formation of dust grains in quasar outflows). It is also possible that the analogies of the dust grains observed near the Galactic center are responsible for the steep reddening curve. In addition, we find that IRAS 14026+4341 is a weak emission-line quasar (i.e., PHL 1811 analogies) with heavy dust reddening and blueshifted broad absorption lines.

  20. A "looming bias" in spatial hearing? Effects of acoustic intensity and spectrum on categorical sound source localization.

    PubMed

    McCarthy, Lisa; Olsen, Kirk N

    2017-01-01

    Continuous increases of acoustic intensity (up-ramps) can indicate a looming (approaching) sound source in the environment, whereas continuous decreases of intensity (down-ramps) can indicate a receding sound source. From psychoacoustic experiments, an "adaptive perceptual bias" for up-ramp looming tonal stimuli has been proposed (Neuhoff, 1998). This theory postulates that (1) up-ramps are perceptually salient because of their association with looming and potentially threatening stimuli in the environment; (2) tonal stimuli are perceptually salient because of an association with single and potentially threatening biological sound sources in the environment, relative to white noise, which is more likely to arise from dispersed signals and nonthreatening/nonbiological sources (wind/ocean). In the present study, we extrapolated the "adaptive perceptual bias" theory and investigated its assumptions by measuring sound source localization in response to acoustic stimuli presented in azimuth to imply looming, stationary, and receding motion in depth. Participants (N = 26) heard three directions of intensity change (up-ramps, down-ramps, and steady state, associated with looming, receding, and stationary motion, respectively) and three levels of acoustic spectrum (a 1-kHz pure tone, the tonal vowel /ә/, and white noise) in a within-subjects design. We first hypothesized that if up-ramps are "perceptually salient" and capable of eliciting adaptive responses, then they would be localized faster and more accurately than down-ramps. This hypothesis was supported. However, the results did not support the second hypothesis. Rather, the white-noise and vowel conditions were localized faster and more accurately than the pure-tone conditions. These results are discussed in the context of auditory and visual theories of motion perception, auditory attentional capture, and the spectral causes of spatial ambiguity.

  1. Active Galactic Nuclei Selected from GALEX Spectroscopy: The Ionizing Source Spectrum at z ~ 1

    NASA Astrophysics Data System (ADS)

    Barger, Amy J.; Cowie, Lennox L.

    2010-08-01

    We use a complete sample of Lyα-emission-line-selected active galactic nuclei (AGNs) obtained from nine deep blank fields observed with the grism spectrographs on the Galaxy Evolution Explorer (GALEX) satellite to measure the normalization and the spectral shape of the AGN contribution to the ionizing background (rest-frame wavelengths 700-900 Å) at z ~ 1. Our sample consists of 139 sources selected in the redshift range z = 0.65-1.25 in the near-ultraviolet (NUV; 2371 Å central wavelength) channel. The area covered is 8.2 deg2 to a NUV magnitude of 20.5 (AB) and 0.92 deg2 at the faintest magnitude limit of 21.8. The GALEX AGN luminosity function agrees well with those obtained using optical and X-ray AGN samples, and the measured redshift evolution of the ionizing volume emissivity is similar to that previously obtained by measuring the GALEX far-ultraviolet (FUV; 1528 Å central wavelength) magnitudes of an X-ray-selected sample. For the first time, we are able to construct the shape of the ionizing background at z ~ 1 in a fully self-consistent way. Based in part on data obtained from the Multimission Archive at the Space Telescope Science Institute (STScI). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for Multimission Archive at STScI (MAST) for non-HST data is provided by the NASA Office of Space Science via grant NAG5-7584 and by other grants and contracts. Based in part on data obtained at 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.

  2. Potential changes of wave steepness and occurrence of rogue waves

    NASA Astrophysics Data System (ADS)

    Bitner-Gregersen, Elzbieta M.; Toffoli, Alessandro

    2015-04-01

    Wave steepness is an important characteristic of a sea state. It is also well established that wave steepness is one of the parameter responsible for generation of abnormal waves called also freak or rogue waves. The study investigates changes of wave steepness in the past and future wave climate in the North Atlantic. The fifth assessment report IPCC (2013) uses four scenarios for future greenhouse gas concentrations in the atmosphere called Representative Concentration Pathways (RCP). Two of these scenarios RCP 4.5 and RCP 8.5 have been selected to project future wave conditions in the North Atlantic. RCP 4.5 is believed to achieve the political target of a maximum global mean temperature increase of 2° C while RPC 8.5 is close to 'business as usual' and expected to give a temperature increase of 4° C or more. The analysis includes total sea, wind sea and swell. Potential changes of wave steepness for these wave systems are shown and compared with wave steepness derived from historical data. Three historical data sets with different wave model resolutions are used. The investigations show also changes in the mean wind direction as well as in the relative direction between wind sea and swell. Consequences of wave steepness changes for statistics of surface elevation and generation of rogue waves are demonstrated. Uncertainties associated with wave steepness projections are discussed.

  3. Very high energy gamma-rays from flat spectrum radio quasars

    NASA Astrophysics Data System (ADS)

    Lindfors, Elina

    2015-03-01

    The detection of Flat Spectrum Radio Quasars (FSRQs) in the Very High Energy (VHE, E>100 GeV) range is challenging, mainly because of their steep soft spectra and distance. Nevertheless four FSRQs are now known to be VHE emitters. The detection of the VHE γ-rays has challenged the emission models of these sources. The sources are also found to exhibit very different behavior. I will give an overview of what is known about the VHE emission of these sources and about the multiwavelength signatures that are connected to the VHE gamma-ray emission.

  4. 318-MHz variability of complete samples of extragalactic radio sources

    NASA Technical Reports Server (NTRS)

    Dennison, B.; Broderick, J. J.; Ledden, J. E.; Odell, S. L.; Condon, J. J.

    1981-01-01

    It is found by a low-frequency variability survey, involving two- and three-epoch, 318-MHz observations of extragalactic sources in samples complete to 3 Jy at 1400 MHz and 1 Jy at 5000 MHz, that steep-spectrum sources do not seem to vary while all flat-spectrum sources exhibit low-frequency variability greater than 8% over about 5 yr. It is also found that the flat-spectrum sources with inverted spectra show the largest fractional variations, and that there is a correlation between the incidence of low-frequency variability and the determination that a source is an optically violent variable. These statistical properties are consistent with models which invoke radio and optical emission relativistic beaming.

  5. Percent Agricultural Land Cover on Steep Slopes (Future)

    EPA Pesticide Factsheets

    Clearing land for agriculture tends to increase soil erosion. The amount of erosion is related to the steepness of the slope, farming methods used and soil type. High amounts of agriculture on steep slopes can increase the amount of soil erosion leading to increased sediment in surface water. Agricultural land cover on steep slopes (AGSL) is the percent of agriculture on slopes greater than or equal to 9%. More information about these resources, including the variables used in this study, may be found here: https://edg.epa.gov/data/Public/ORD/NERL/ReVA/ReVA_Data.zip.

  6. Improved numerical modeling of morphodynamics of rivers with steep banks

    NASA Astrophysics Data System (ADS)

    Langendoen, Eddy J.; Mendoza, Alejandro; Abad, Jorge D.; Tassi, Pablo; Wang, Dongchen; Ata, Riadh; El kadi Abderrezzak, Kamal; Hervouet, Jean-Michel

    2016-07-01

    The flow and sediment transport processes near steep streambanks, which are commonly found in meandering, braided, and anastomosing stream systems, exhibit complex patterns that produce intricate interactions between bed and bank morphologic adjustment. Increasingly, multi-dimensional computer models of riverine morphodynamics are used to aid in the study of these processes. A number of depth-averaged two-dimensional models are available to simulate morphologic adjustment of both bed and banks. Unfortunately, these models use overly simplified conceptual models of riverbank erosion, are limited by inflexible structured mesh systems, or are unable to accurately account for the flow and sediment transport adjacent to streambanks of arbitrary geometry. A new, nonlinear model is introduced that resolves these limitations. The model combines the river morphodynamics computer models TELEMAC-2D and SISYPHE of the open source TELEMAC-MASCARET suite of solvers with the bank erosion modules of the CONCEPTS channel evolution computer model. The performance of the new model is evaluated for meander-planform initiation and development. The most important findings are: (1) the model is able to simulate a much greater variety and complexity in meander wavelengths; (2) simulated meander development agrees closely with the unified bar-bend theory of Tubino and Seminara (1990); and (3) the rate of meander planform adjustment is greatly reduced if the wavelength of alternate bars is similar to that of meanders.

  7. Steep front short duration low voltage impulse performance of distribution transformers

    SciTech Connect

    Burrage, L.M.; Veverka, E.F.; McConnell, B.W.

    1987-01-01

    An extensive literature search of steep front short duration (SFSD) impulse sources, their characteristics and effect on power system equipment has led to the specification of a test program to evaluate key apparatus and insulations. Distribution transformers, although not overly susceptible to impulse damage, have been selected as one of the candidate apparatus for low and high voltage SFSD impulse tests. This paper covers the low voltage SFSD impulse response of conventional oil insulated shell form and core form distribution transformers.

  8. Channel erosion in steep gradient, gravel-paved streams

    SciTech Connect

    Lepp, L.R.; Koger, C.J.; Wheeler, J.A.

    1993-12-01

    Discharges were measured in steep gradient (> 5 percent) gravel-paved streams from 1988 to 1991 in order to empirically determine erosional thresholds based on sediment size, related to critical velocity, tractive force, and unit stream power. Results suggest that the empirical relationship between sediment size and unit stream power provides an accurate and simple methodology for determining the minimum erosion threshold discharge for steep gradient streams common in western Washington and other similar mountain terrains.

  9. Measurement of the neutron spectrum and ambient neutron dose rate equivalent from the small 252Cf source at 1 meter

    SciTech Connect

    Radev, R.

    2015-07-07

    NASA Langley Research Center requested a measurement of the neutron spectral distribution and fluence from the 252Cf source (model NS-120, LLNL serial # 7001677, referred as the SMALL Cf source) and determination of the ambient neutron dose rate equivalent and kerma at 100 cm for the Radiation Budget Instrument Experiment (Rad-X). The dosimetric quantities should be based on the neutron spectrum and the current neutron-to-dose conversion coefficients.

  10. An event-related source localization study of response monitoring and social impairments in autism spectrum disorder.

    PubMed

    Santesso, Diane L; Drmic, Irene E; Jetha, Michelle K; Bryson, Susan E; Goldberg, Joel O; Hall, Geoffrey B; Mathewson, Karen J; Segalowitz, Sidney J; Schmidt, Louis A

    2011-02-01

    A number of studies suggest anterior cingulate cortex (ACC) abnormalities in autism spectrum disorder (ASD), which might underlie response monitoring and social impairments exhibited by children and adolescents with ASD. The goal of the present study was to extend this work by examining error and correct response monitoring using event-related potentials (ERN, Pe, CRN) and LORETA source localization in high functioning adults with ASD and controls. Adults with ASD showed reduced ERN and Pe amplitudes and reduced rostral ACC activation compared with controls. Adults with ASD also showed less differentiation between error and correct ERP components. Social impairments and higher overall autism symptoms were related to reduced rostral ACC activity at the time of the ERN, particularly in adults with ASD. These findings suggest that reduced ACC activity may reflect a putative brain mechanism involved in the origins and maintenance of social impairments and raise the possibility of the presence of stable brain-behavior relation impairment across development in some individuals with ASD.

  11. Continuation of the Pursuit of the Far-Infrared Spectrum of Ncncs, at the Canadian Light Source

    NASA Astrophysics Data System (ADS)

    Winnewisser, Manfred; Winnewisser, Brenda P.; De Frank, C. Lucia; Tokaryk, Dennis W.; Ross, Stephen C.; Billinghurst, Brant E.

    2013-06-01

    The molecule cyanogen iso-thiocyanate, NCNCS, has proved to be the most revealing model system for studying the effects of molecular quantum monodromy. In two previous measuring campaigns in May 2011 and May 2012 at the Canadian Light Source (CLS) at the University of Saskatchewan we have obtained a rich collection of high-resolution infrared band systems for both S(CN)_{2} and its isomer NCNCS which is our target molecule. We found experimentally that NCNCS is the more stable isomer. Some results for S(CN)_{2} are reported in the adjacent talk in this session. However, the isomerization between S(CN)_{2} and NCNCS and other reaction products make the attainment of a pure sample of NCNCS difficult and time consuming. We have not yet obtained a satisfactory high-resolution recording of the quasi-linear bending mode in the far infrared in the two allotments of beam time so far available to us. Our theoretical preparations for the project include recent refinements of predictions of intensities in the low-lying bending mode band system, which will be shown. The experimental aspects of obtaining an optimal sample of NCNCS in order to observe the rotational resolved spectrum in the CLS campaign scheduled for May 2013, and an initial report of the results, will also be discussed. B. P. Winnewisser, M. Winnewisser, I. R. Medvedev, F. C. {De Lucia}, S. C. Ross and J. Koput, Phys. Chem. Chem. Phys., {12}, 8158 (2010)

  12. Predictors of Age of Diagnosis for Children with Autism Spectrum Disorder: The Role of a Consistent Source of Medical Care, Race, and Condition Severity

    ERIC Educational Resources Information Center

    Emerson, Natacha D.; Morrell, Holly E. R.; Neece, Cameron

    2016-01-01

    Having a consistent source of medical care may facilitate diagnosis of autism spectrum disorders (ASD). This study examined predictors of age of ASD diagnosis using data from the 2011-2012 National Survey of Children's Health. Using multiple linear regression analysis, age of diagnosis was predicted by race, ASD severity, having a consistent…

  13. VLA observations of unidentified Leiden-Berkeley Deep-Survey sources - Luminosity and redshift dependence of spectral properties

    NASA Technical Reports Server (NTRS)

    Kapahi, Vijay K.; Kulkarni, Vasant K.

    1990-01-01

    VLA observations of a complete subset of the Leiden-Berkeley Deep Survey sources that have S(1.4 GHz) greater than 10 mJy and are not optically identified down to F=22 mag are reported. By comparing the spectral and structural properties of the sources with samples from the literature, an attempt was made to disentangle the luminosity and redshift dependence of the spectral indices of extended emission in radio galaxies and of the incidence of compact steep-spectrum sources. It is found that the fraction of compact sources among those with a steep spectrum is related primarily to redshift, being much larger at high redshifts for sources of similar radio luminosity. Only a weak and marginally significant dependence of spectral indices of the extended sources on luminosity and redshift is found in samples selected at 1.4 and 2.7 GHz. It is pointed out that the much stronger correlation of spectral indices with luminosity may be arising partly from spectral curvature, and partly due to the preferential inclusion of very steep-spectrum sources from high redshift in low-frequency surveys.

  14. Photomorphogenesis and photoassimilation in soybean and sorghum grown under broad spectrum or blue-deficient light sources

    NASA Technical Reports Server (NTRS)

    Britz, S. J.; Sager, J. C.; Knott, W. M. (Principal Investigator)

    1990-01-01

    The role of blue light in plant growth and development was investigated in soybean (Glycine max [L.] Merr. cv Williams) and sorghum (Sorghum bicolor [L.] Moench. cv Rio) grown under equal photosynthetic photon fluxes (approximately 500 micromoles per square meter per second) from broad spectrum daylight fluorescent or blue-deficient, narrow-band (589 nanometers) low pressure sodium (LPS) lamps. Between 14 and 18 days after sowing, it was possible to relate adaptations in photosynthesis and leaf growth to dry matter accumulation. Soybean development under LPS light was similar in several respects to that of shaded plants, consistent with an important role for blue light photoreceptors in regulation of growth response to irradiance. Thus, soybeans from LPS conditions partitioned relatively more growth to leaves and maintained higher average leaf area ratios (mean LAR) that compensated lower net assimilation rates (mean NAR). Relative growth rates were therefore comparable to plants from daylight fluorescent lamps. Reductions in mean NAR were matched by lower rates of net photosynthesis (A) on an area basis in the major photosynthetic source (first trifoliolate) leaf. Lower A in soybean resulted from reduced leaf dry matter per unit leaf area, but lower A under LPS conditions in sorghum correlated with leaf chlorosis and reduced total nitrogen (not observed in soybean). In spite of a lower A, mean NAR was larger in sorghum from LPS conditions, resulting in significantly greater relative growth rates (mean LAR was approximately equal for both light conditions). Leaf starch accumulation rate was higher for both species and starch content at the end of the dark period was elevated two- and three-fold for sorghum and soybean, respectively, under LPS conditions. Possible relations between starch accumulation, leaf export, and plant growth in response to spectral quality were considered.

  15. Radio-Optical Analysis of Extended Radio Sources in the First Look Survey Field

    NASA Astrophysics Data System (ADS)

    Paulo, C. M.; Prandoni, I.; Morganti, R.; Cress, C. M.

    2010-05-01

    We combine 610 MHz GMRT data, 1.4 GHz VLA data, and 1.4 GHz WSRT observations, encompassing a ~ 4 square degree field centered on the verification strip of the Spitzer First Look Survey field, to study radio sources down to fluxes of about 0.1 mJy. The spectral index (Figure 1) analysis shows that the majority of multi-component sources are steep-spectrum sources. Nevertheless the spread in the spectral distribution is wide, with a significant number of ultra-steep, flat or inverted sources, possibly indicating a wider range of accretion modes in fainter samples. By cross-correlating 107 multi-component radio sources with the optical catalogues of Marleau et al. (2007) and Papovich et al. (2006), 23 objects were identified.

  16. Wave Reflection on a Two-Slope Steep Beach

    DTIC Science & Technology

    2012-03-01

    ABSTRACT (maximum 200 words) Wave reflection of sea-swell (0.05–0.20 Hz) energy on a two-slope (1/7.6 nearshore and 1/19 offshore) steep beach with no...amplitude long period waves produced energy reflection coefficients up to 80%, with most in the 30–50% range. There was a measured increase in the...PAGE INTENTIONALLY LEFT BLANK v ABSTRACT Wave reflection of sea-swell (0.05–0.20 Hz) energy on a two-slope (1/7.6 nearshore and 1/19 offshore) steep

  17. Distribution transformer performance when subjected to steep front impulses

    SciTech Connect

    Burrage, L.M.; Shaw, J.H. . Thomas A. Edison Technical Center); McConnell, B.W. )

    1990-04-01

    The experimental method and the results of subjecting arrester protected pole type distribution transformers to the combined stresses caused by the conducted steep front impulse and rated 60 Hz voltages are described. Comparisons are drawn between these results and those of similar experiments on unenergized distribution transformers. It is concluded that tank mounted direct connected arresters provide a high degree of protection to these transformers, tank mounted externally gapped or crossarm mounted arresters may not provide sufficient protection; internal transformer insulation system failures caused by the steep front impulse do not necessarily result in immediate catastrophic failures of the transformers.

  18. Measurement of steep edges and undercuts in confocal microscopy.

    PubMed

    Mueller, T; Jordan, M; Schneider, T; Poesch, A; Reithmeier, E

    2016-05-01

    Confocal microscopy is widely used to measure the surface topography of specimen with a precision in the micrometer range. The measurement uncertainty and quality of the acquired data of confocal microscopy depends on various effects, such as optical aberrations, vibrations of the measurement setup and variations in the surface reflectivity. In this article, the influence of steep edges and undercuts on measurement results is examined. Steep edges on the specimen's surface lead to a reduced detector signal which influences the measurement accuracy and undercuts cause surface regions, which cannot be captured in a measurement. The article describes a method to overcome the negative effects of steep edges and undercuts by capturing several measurements of the surface with different angles between the surface and the optical axis of the objective. An algorithm is introduced which stitches different angle measurements together without knowledge of the exact position and orientation of the rotation axis. Thus, the measurement uncertainty due to steep edges and undercuts can be avoided without expensive high-precision rotation stages and time consuming adjustment of the measurement setup.

  19. Improved numerical modelling of morphodynamics of rivers with steep banks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The flow and sediment transport processes near steep streambanks, which are commonly found in meandering, braided, and anastomosing stream systems, exhibit complex patterns. The interactions between bed and bank morphologic adjustment, and their governing processes are still not well understood. Inc...

  20. 30 CFR 785.15 - Steep slope mining.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Steep slope mining. 785.15 Section 785.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR SURFACE COAL MINING AND RECLAMATION OPERATIONS PERMITS AND COAL EXPLORATION SYSTEMS UNDER REGULATORY...

  1. 30 CFR 785.15 - Steep slope mining.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Steep slope mining. 785.15 Section 785.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR SURFACE COAL MINING AND RECLAMATION OPERATIONS PERMITS AND COAL EXPLORATION SYSTEMS UNDER REGULATORY...

  2. 30 CFR 785.15 - Steep slope mining.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Steep slope mining. 785.15 Section 785.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR SURFACE COAL MINING AND RECLAMATION OPERATIONS PERMITS AND COAL EXPLORATION SYSTEMS UNDER REGULATORY...

  3. 30 CFR 785.15 - Steep slope mining.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Steep slope mining. 785.15 Section 785.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR SURFACE COAL MINING AND RECLAMATION OPERATIONS PERMITS AND COAL EXPLORATION SYSTEMS UNDER REGULATORY...

  4. 30 CFR 785.15 - Steep slope mining.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Steep slope mining. 785.15 Section 785.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR SURFACE COAL MINING AND RECLAMATION OPERATIONS PERMITS AND COAL EXPLORATION SYSTEMS UNDER REGULATORY...

  5. Surprises from a Deep ASCA Spectrum of the Broad Absorption Line Quasar PHL 5200

    NASA Technical Reports Server (NTRS)

    Mathur, Smita; Matt, G.; Green, P. J.; Elvis, M.; Singh, K. P.

    2002-01-01

    We present a deep (approx. 85 ks) ASCA observation of the prototype broad absorption line quasar (BALQSO) PHL 5200. This is the best X-ray spectrum of a BALQSO yet. We find the following: (1) The source is not intrinsically X-ray weak. (2) The line-of-sight absorption is very strong, with N(sub H) = 5 x 10(exp 23)/sq cm. (3) The absorber does not cover the source completely; the covering fraction is approx. 90%. This is consistent with the large optical polarization observed in this source, implying multiple lines of sight. The most surprising result of this observation is that (4) the spectrum of this BALQSO is not exactly similar to other radio-quiet quasars. The hard X-ray spectrum of PHL 5200 is steep, with the power-law spectral index alpha approx. 1.5. This is similar to the steepest hard X-ray slopes observed so far. At low redshifts, such steep slopes are observed in narrow-line Seyfert 1 (NLS1) galaxies, believed to be accreting at a high Eddington rate. This observation strengthens the analogy between BALQSOs and NLS1 galaxies and supports the hypothesis that BALQSOs represent an early evolutionary state of quasars. It is well accepted that the orientation to the line of sight determines the appearance of a quasar: age seems to play a significant role as well.

  6. Optical spectroscopy of four young radio sources

    NASA Astrophysics Data System (ADS)

    Fan, Xu-Liang; Bai, Jin-Ming; Hu, Chen; Wang, Jian-Guo

    2017-01-01

    We report the optical spectroscopy of four young radio sources which are observed with the Lijiang 2.4 m telescope. The Eddington ratios of these sources are similar with those of narrow-line Seyfert 1 galaxies (NLS1s). Their Fe II emission is strong while [O III] strength is weak. These results confirm the NLS1 features of young radio sources, except that the width of broad Hβ of young radio sources is larger than that of NLS1s. We thus suggest that the young radio sources are the high black hole mass counterparts of steep-spectrum radio-loud NLS1s. In addition, the broad Hβ component of 4C 12.50 is the blue wing of the narrow component, but not from the broad line region.

  7. The spectral variability of the GHZ-Peaked spectrum radio source PKS 1718-649 and a comparison of absorption models

    SciTech Connect

    Tingay, S. J.; Macquart, J.-P.; Wayth, R. B.; Trott, C. M.; Emrich, D.; Collier, J. D.; Wong, G. F.; Rees, G.; Stevens, J.; Carretti, E.; Callingham, J. R.; Gaensler, B. M.; McKinley, B.; Briggs, F.; Bernardi, G.; Bowman, J. D.; Cappallo, R. J.; Corey, B. E.; Deshpande, A. A.; Goeke, R.; and others

    2015-02-01

    Using the new wideband capabilities of the ATCA, we obtain spectra for PKS 1718-649, a well-known gigahertz-peaked spectrum radio source. The observations, between approximately 1 and 10 GHz over 3 epochs spanning approximately 21 months, reveal variability both above the spectral peak at ∼3 GHz and below the peak. The combination of the low- and high-frequency variability cannot be easily explained using a single absorption mechanism, such as free–free absorption or synchrotron self-absorption. We find that the PKS 1718-649 spectrum and its variability are best explained by variations in the free–free optical depth on our line of sight to the radio source at low frequencies (below the spectral peak) and the adiabatic expansion of the radio source itself at high frequencies (above the spectral peak). The optical depth variations are found to be plausible when X-ray continuum absorption variability seen in samples of active galactic nuclei is considered. We find that the cause of the peaked spectrum in PKS 1718-649 is most likely due to free–free absorption. In agreement with previous studies, we find that the spectrum at each epoch of observation is best fit by a free–free absorption model characterized by a power-law distribution of free–free absorbing clouds. This agreement is extended to frequencies below the 1 GHz lower limit of the ATCA by considering new observations with Parkes at 725 MHz and 199 MHz observations with the newly operational Murchison Widefield Array. These lower frequency observations argue against families of absorption models (both free–free and synchrotron self-absorption) that are based on simple homogenous structures.

  8. The BL LAC phenomenon: X-ray observations of transition objects and determination of the x-ray spectrum of a complete sample of flat-spectrum radio sources

    NASA Technical Reports Server (NTRS)

    Worrall, Diana M.

    1994-01-01

    This report summarizes the activities related to two ROSAT investigations: (1) x-ray properties of radio galaxies thought to contain BL Lac type nuclei; and (2) x-ray spectra of a complete sample of flat-spectrum radio sources. The following papers describing the research are provided as attachments: Multiple X-ray Emission Components in Low Power Radio Galaxies; New X-ray Results on Radio Galaxies; Analysis Techniques for a Multiwavelength Study of Radio Galaxies; Separation of X-ray Emission Components in Radio Galaxies; X-ray Emission in Powerful Radio Galaxies and Quasars; Extended and Compact X-ray Emission in Powerful Radio Galaxies; and X-ray Spectra of a Complete Sample of Extragalactic Core-dominated Radio Sources.

  9. Damage mechanisms and influence of gradation for steep riprap

    SciTech Connect

    Rohan, K.; Belfadhel, M.B.; Lefebvre, G. ); Dascal, O. )

    1994-03-01

    Model tests in a laboratory flume were performed to verify certain hypotheses put forward to explain steep riprap behavior observed in the field at several embankment dam sites. The laboratory study has focused on riprap degradation under wave attack, and on the influence of fine blocks incorporated into riprap. Unlike flatter riprap, steep riprap is characterized by a low rate of damage until a point of acceleration, after which damage progresses rapidly. At that stage, damage is characterized by sliding and crumbling, which results in an upward propagation of damage toward the crest. The inclusion of a portion of small blocks into the riprap significantly reduces the stability of seep riprap. This detrimental effect is gradually reduced as the riprap slope becomes flatter.

  10. Flight dynamics of rotorcraft in steep high-g turns

    NASA Technical Reports Server (NTRS)

    Chen, R. T. N.

    1982-01-01

    An analyticl procedure developed to permit a systematic examination of rotorcraft flight dynamics in steep high-g turns is presented. The procedure is used in a numerical investigation of a tilt-rotor aircraft and three single-rotor helicopters that have different types of main rotor systems. The results indicate (1) that strong coupling in longitudinal and lateral-directional motions exists for these rotorcraft in high-g turns; (2) that for single-rotor helicopters, the direction of turn has a significant influence on flight dynamics; and (3) that a stability and control augmentation system that is designed on the basis of standard small-disturbance equations of motion from steady straight and level flight and that otherwise performs satisfactorily in operations near 1 g, becomes significantly degraded in steep turning flight.

  11. DISCOVERY AND MONITORING OF A NEW BLACK HOLE CANDIDATE XTE J1752-223 WITH RXTE: RMS SPECTRUM EVOLUTION, BLACK HOLE MASS, AND THE SOURCE DISTANCE

    SciTech Connect

    Shaposhnikov, Nikolai

    2010-11-10

    We report on the discovery and monitoring observations of a new galactic black hole (BH) candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on 2009 October 21 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/high-soft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass BH binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a blackbody spectrum gets reprocessed in the Comptonizing medium. We follow the evolution of fractional root-mean-square (rms) variability in the RXTE/PCA energy band with the source spectral state and conclude that broadband variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition, and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observations during the hard-to-soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source of about 3.5 kpc.

  12. Discovery and Monitoring of a New Black Hole Candidate XTE J1752-223 with RXTE: RMS Spectrum Evolution, BH Mass and the Source Distance

    NASA Technical Reports Server (NTRS)

    Shaposhinikov, Nikolai; Markwardt, Craig; Swank, Jean; Krimm, Hans

    2010-01-01

    We report on the discovery and monitoring observations of a new galactic black hole candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on October 21 2009 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/highsoft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass black hole binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a black body spectrum gets reprocessed in the Comptonizing medium. We follow the evolution of fractional root-mean-square (RMS) variability in the RXTE/PCA energy band with the source spectral state and conclude that broad band variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observations during the hardto- soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source about 3.5 kiloparsec.

  13. On the existence of smooth Cauchy steep time functions

    NASA Astrophysics Data System (ADS)

    Minguzzi, E.

    2016-06-01

    A simple proof (based on results in Chruściel et al 2015 Ann. Henri Poincaré arXiv:1301.2909) is given that every globally hyperbolic spacetime admits a smooth Cauchy steep time function. This result is useful in order to show that globally hyperbolic spacetimes can be isometrically embedded in Minkowski spacetimes and that they split as a product. The proof is based on a recent result on the differentiability of Geroch’s volume functions.

  14. Steep Turn On/Off "Green" Tunnel Transistors

    DTIC Science & Technology

    2010-12-17

    Steep Turn On/Off "Green" Tunnel Transistors Pratik Ashvin Patel Electrical Engineering and Computer Sciences University of California at Berkeley...ES) University of California at Berkeley,Department of Electrical Engineering and Computer Sciences,Berkeley,CA,94720 8. PERFORMING ORGANIZATION...presents a serious thermal management challenge and potential limiter of integration density as well as a rapidly growing portion of the world electricity

  15. Emplacement and composition of steep-sided domes on Venus

    NASA Astrophysics Data System (ADS)

    Stofan, Ellen R.; Anderson, Steven W.; Crown, David A.; Plaut, Jeffrey J.

    2000-11-01

    Steep-sided domes on Venus have surface characteristics that can provide information on their emplacement, including relatively smooth upper surfaces, radial and polygonal fracture patterns, and pits. These characteristics indicate that domes have surface crusts which are relatively unbroken, have mobile interiors after emplacement, and preserve fractures from only late in their history in response to endogenous growth or sagging of the dome surface. We have calculated the time necessary to form a 12-cm-thick crust for basalt and rhyolite under current terrestrial and Venusian ambient conditions. A 12-cm-thick crust will form in all cases in <10 hours. Although Venusian lava flows should develop a brittle carapace during emplacement, only late-stage brittle fractures are preserved at steep-sided domes. We favor an emplacement model where early-formed surface crusts are entrained or continually annealed as they deform to accommodate dome growth. Entrainment and annealing of fractures are not mutually exclusive processes and thus may both be at work during steep-sided dome emplacement. Our results are most consistent with basaltic compositions, as rhyolitic lavas would quickly form thick crusts which would break into large blocks that would be difficult to entrain or anneal. However, if Venus has undergone large temperature excursions in the past (producing ambient conditions of 800-1000 K [e.g., Bullock and Grinspoon, 1996, 1998]), rhyolitic lavas would be unable to form crusts at high surface temperatures and could produce domes with surface characteristics consistent with those of Venusian steep-sided domes.

  16. Formation mechanism of steep wave front in magnetized plasmas

    SciTech Connect

    Sasaki, M. Kasuya, N.; Itoh, S.-I.; Kobayashi, T.; Arakawa, H.; Itoh, K.; Fukunaga, K.; Yamada, T.; Yagi, M.

    2015-03-15

    Bifurcation from a streamer to a solitary drift wave is obtained in three dimensional simulation of resistive drift waves in cylindrical plasmas. The solitary drift wave is observed in the regime where the collisional transport is important as well as fluctuation induced transport. The solitary drift wave forms a steep wave front in the azimuthal direction. The phase of higher harmonic modes are locked to that of the fundamental mode, so that the steep wave front is sustained for a long time compared to the typical time scale of the drift wave oscillation. The phase entrainment between the fundamental and second harmonic modes is studied, and the azimuthal structure of the stationary solution is found to be characterized by a parameter which is determined by the deviation of the fluctuations from the Boltzmann relation. There are two solutions of the azimuthal structures, which have steep wave front facing forward and backward in the wave propagation direction, respectively. The selection criterion of these solutions is derived theoretically from the stability of the phase entrainment. The simulation result and experimental observations are found to be consistent with the theoretical prediction.

  17. Results on the primary CR spectrum and composition reconstructed with the SPHERE-2 detector

    NASA Astrophysics Data System (ADS)

    Antonov, R. A.; Beschapov, S. P.; Bonvech, E. A.; Chernov, D. V.; Dzhatdoev, T. A.; Finger, Mir; Finger, Mix; Galkin, V. I.; Kabanova, N. V.; Petkun, A. S.; Podgrudkov, D. A.; Roganova, T. M.; Shaulov, S. B.; Sysoeva, T. I.

    2013-02-01

    First preliminary results of the balloon-borne experiment SPHERE-2 on the all-nuclei primary cosmic rays (PCR) spectrum and primary composition are presented. The primary spectrum in the energy range 1016-5 · 1017 eV was reconstructed using characteristics of Vavilov-Cherenkov radiation of extensive air showers (EAS), reflected from a snow surface. Several sources of systematic uncertainties of the spectrum were analysed. A method for separation of the primary nuclei' groups based on the lateral distribution function' (LDF) steepness parameter is presented. Preliminary estimate of the mean light nuclei' fraction f30-150 at energies 3 · 1016-1.5 · 1017 eV was performed and yielded f30-150 = (21±11) %.

  18. Photon energy spectrum emitted by a novel polymer-encapsulated {sup 103}Pd source and its effect on the dose rate constant

    SciTech Connect

    Khan, Sabrina; Chen, Zhe Jay; Nath, Ravinder

    2008-04-15

    Two independent groups have published intrinsic dosimetry parameters for the recently introduced OptiSeed{sup 103} interstitial brachytherapy source which contains {sup 103}Pd encapsulated by a novel polymer shell. The dose rate constant ({lambda}) reported by the two groups, however, differed by more than 6% and there is currently no AAPM recommended consensus value for this source in clinical dosimetry. The aim of this work was to perform an independent determination of {lambda} for the OptiSeed{sup 103} source using a recently developed photon spectrometry technique. Three OptiSeed{sup 103} sources (model 1032P) with known air-kerma strength were used in this study. The photon energy spectrum emitted along the radial direction on the source's bisector was measured in air using a high-resolution intrinsic germanium spectrometer designed and established for low-energy brachytherapy source spectrometry. The dose rate constant of each source was determined from its emitted energy spectrum and the spatial distribution of radioactivity in the source. Unlike other sources made with traditional titanium encapsulation, the photons emitted by the OptiSeed{sup 103} sources exhibited only slight spectral hardening, yielding a relative energy spectrum closer to that emitted by bare {sup 103}Pd. The dose rate constant determined by the photon spectrometry technique for water was 0.664{+-}0.025 cGy h{sup -1} U{sup -1}. This value agreed, within experimental uncertainties, with the Monte Carlo-calculated value ({sub MC}{lambda}) of 0.665{+-}0.014 cGy h{sup -1} U{sup -1} and the TLD-measured value (with a Monte Carlo-calculated solid-phantom-to-water conversion factor) of 0.675{+-}0.051 cGy h{sup -1} U{sup -1} reported by Wang and Hertel [Appl. Radiat. Isot. 63, 311-321 (2005)]. However, it differed by -6.7% from the {sub MC}{lambda} of 0.712{+-}0.043 cGy h{sup -1} U{sup -1} reported by Bernard and Vynckier [Phys. Med. Biol. 50, 1493-1504 (2005)]. The results obtained in this

  19. Compact, High-Power, Fiber-Laser-Based Coherent Sources Tunable in the Mid-Infrared and THz Spectrum

    DTIC Science & Technology

    2015-02-20

    Ti:sapphire laser as pump source. In cw operation, we have achieved world-record output powers, while in the ultrafast femtosecond time-scale we have...continuous-wave (cw) and ultrafast femtosecond time-scales using compact fiber lasers and Kerr-lensmode- locked Ti:sapphire laser as pump source. In cw...compact fiber lasers and Kerr-lens- mode-locked Ti:sapphire laser as pump source. In cw operation, we have achieved world-record output powers, while in

  20. Radiation detector spectrum simulator

    DOEpatents

    Wolf, M.A.; Crowell, J.M.

    1985-04-09

    A small battery operated nuclear spectrum simulator having a noise source generates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith to generate several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

  1. Radiation detector spectrum simulator

    DOEpatents

    Wolf, Michael A.; Crowell, John M.

    1987-01-01

    A small battery operated nuclear spectrum simulator having a noise source nerates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith generates several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

  2. Multifrequency polarimetry of a complete sample of PACO radio sources

    NASA Astrophysics Data System (ADS)

    Galluzzi, V.; Massardi, M.; Bonaldi, A.; Casasola, V.; Gregorini, L.; Trombetti, T.; Burigana, C.; De Zotti, G.; Ricci, R.; Stevens, J.; Ekers, R. D.; Bonavera, L.; di Serego Alighieri, S.; Liuzzo, E.; López-Caniego, M.; Mignano, A.; Paladino, R.; Toffolatti, L.; Tucci, M.

    2017-03-01

    We present high-sensitivity polarimetric observations (σP ≃0.6 mJy) in six bands covering the 5.5-38 GHz range of a complete sample of 53 compact extragalactic radio sources brighter than 200 mJy at 20 GHz. The observations, carried out with the Australia Telescope Compact Array, achieved a 91 per cent detection rate (at 5σ). Within this frequency range, the spectra of about 95 per cent of sources are well fitted by double power laws, both in total intensity and in polarization, but the spectral shapes are generally different in the two cases. Most sources were classified as either steep- or peaked-spectrum but less than 50 per cent have the same classification in total and in polarized intensity. No significant trends of the polarization degree with flux density or with frequency were found. The mean variability index in total intensity of steep-spectrum sources increases with frequency for a 4-5 yr lag, while no significant trend shows up for the other sources and for the 8 yr lag. In polarization, the variability index, which could be computed only for the 8 yr lag, is substantially higher than in total intensity and has no significant frequency dependence.

  3. Transient river response, captured by channel steepness and its concavity

    NASA Astrophysics Data System (ADS)

    Vanacker, Veerle; von Blanckenburg, Friedhelm; Govers, Gerard; Molina, Armando; Campforts, Benjamin; Kubik, Peter W.

    2015-01-01

    Mountain rivers draining tropical regions are known to be great conveyor belts carrying efficiently more than half of the global sediment flux to the oceans. Many tropical mountain areas are located in tectonically active belts where the hillslope and stream channel morphology are rapidly evolving in response to changes in base level. Here, we report basin-wide denudation rates for an east-west transect through the tropical Andes. Hillslope and channel morphology vary systematically from east to west, reflecting the transition from high relief, strongly dissected topography in the escarpment zones into relatively low relief topography in the inter-Andean valley. The spatial pattern of differential denudation rates reflects the transient adjustment of the landscape to rapid river incision following tectonic uplift and river diversion. In the inter-Andean valley, upstream of the wave of incision, slopes and river channels display a relatively smooth, concave-up morphology and denudation rates (time scale of 104-105 a) are consistently low (3 to 200 mm/ka). In contrast, slopes and river channels of rejuvenated basins draining the eastern cordillera are steep to very steep; and the studied drainage basins show a wide range of denudation rate values (60 to 400 mm/ka) that increase systematically with increasing basin mean slope gradient, channel steepness, and channel convexity. Drainage basins that are characterised by strong convexities in their river longitudinal profiles systematically have higher denudation rates. As such, this is one of the first studies that provides field-based evidence of a correlation between channel concavity and basin mean denudation rates, consistent with process-based fluvial incision models.

  4. Stability of steep gravity capillary solitary waves in deep water

    NASA Astrophysics Data System (ADS)

    Calvo, David C.; Akylas, T. R.

    2002-02-01

    The stability of steep gravity capillary solitary waves in deep water is numerically investigated using the full nonlinear water-wave equations with surface tension. Out of the two solution branches that bifurcate at the minimum gravity capillary phase speed, solitary waves of depression are found to be stable both in the small-amplitude limit when they are in the form of wavepackets and at finite steepness when they consist of a single trough, consistent with observations. The elevation-wave solution branch, on the other hand, is unstable close to the bifurcation point but becomes stable at finite steepness as a limit point is passed and the wave profile features two well-separated troughs. Motivated by the experiments of Longuet-Higgins & Zhang (1997), we also consider the forced problem of a localized pressure distribution applied to the free surface of a stream with speed below the minimum gravity capillary phase speed. We find that the finite-amplitude forced solitary-wave solution branch computed by Vanden-Broeck & Dias (1992) is unstable but the branch corresponding to Rayleigh’s linearized solution is stable, in agreement also with a weakly nonlinear analysis based on a forced nonlinear Schrödinger equation. The significance of viscous effects is assessed using the approach proposed by Longuet-Higgins (1997): while for free elevation waves the instability predicted on the basis of potential-flow theory is relatively weak compared with viscous damping, the opposite turns out to be the case in the forced problem when the forcing is strong. In this régime, which is relevant to the experiments of Longuet-Higgins & Zhang (1997), the effects of instability can easily dominate viscous effects, and the results of the stability analysis are used to propose a theoretical explanation for the persistent unsteadiness of the forced wave profiles observed in the experiments.

  5. The 9Be(d,n) 10B-reaction as intense neutron source with continuous energy spectrum

    NASA Astrophysics Data System (ADS)

    Baumann, F. M.; Domogala, G.; Freiesleben, H.; Paul, H. J.; Puhlvers, S.; Sohlbach, H.

    1986-06-01

    Neutron energy spectra produced by deuterons of 3 to 8 MeV in a thick 9Be-target were measured at various scattering angles. Significant angle dependences were observed. Angular distributions of the most energetic neutrons produced in thin 9Be targets can be described quantitatively in DWBA, which is an indication for a direct reaction mechanism. As a consequence all but 0°-neutrons are polarized to a certain extent. Also presented is the neutron energy spectrum of 7Li(d,n) 8Be at 0° produced in a thick 7Li-target. The potential of these intense 0°-neutron beams with continuous energy distributions is demonstrated by a measurement of the neutron absorption cross section of natural carbon.

  6. Measurements and analysis of bremsstrahlung x-ray spectrum obtained in NANOGAN electron cyclotron resonance ion source

    SciTech Connect

    Baskaran, R.; Selvakumaran, T. S.; Rodrigues, G.; Kanjilal, D.; Roy, A.

    2008-02-15

    From the ECR plasma, hot electrons leak across the magnetic lines of force and by striking the plasma chamber produce bremsstrahlung x-rays. The wall bremsstrahlung gives information on the confinement status of hot electron. In our studies, experimental measurements are carried out in NANOGAN electron cyclotron resonance (ECR) ion source for the wall bremsstrahlung x-rays and the results are presented. While optimizing a particular charge state in ECR ion source, experimental parameters are adjusted to get a maximum current. The wall bremsstrahlung components are studied in these cases for understanding the hot electron confinement conditions.

  7. Global dynamics for steep nonlinearities in two dimensions

    NASA Astrophysics Data System (ADS)

    Gedeon, Tomáš; Harker, Shaun; Kokubu, Hiroshi; Mischaikow, Konstantin; Oka, Hiroe

    2017-01-01

    This paper discusses a novel approach to obtaining mathematically rigorous results on the global dynamics of ordinary differential equations. We study switching models of regulatory networks. To each switching network we associate a Morse graph, a computable object that describes a Morse decomposition of the dynamics. In this paper we show that all smooth perturbations of the switching system share the same Morse graph and we compute explicit bounds on the size of the allowable perturbation. This shows that computationally tractable switching systems can be used to characterize dynamics of smooth systems with steep nonlinearities.

  8. Field experiments of nonlocal sediment transport on a steep hillslope

    NASA Astrophysics Data System (ADS)

    DiBiase, R.; Booth, A. M.; Ganti, V.; Scheingross, J. S.; Lamb, M. P.

    2014-12-01

    Steep rocky hillslopes dominate the areal extent of rapidly uplifting mountain ranges, and pose a significant hazard to encroaching population centers. Existing models for hillslope sediment transport developed for soil-mantled landscapes are poorly suited to explain the evolution of steep hillslopes characterized by: (1) intermittent or patchy soil cover, (2) slopes that exceed the angle of repose, and (3) transport events that often involve long travel distances. Recently, nonlocal formulations of hillslope sediment transport laws that account for long travel distances have been proposed to overcome the limitations of traditional continuum-based models. However, their application to natural landscapes has been limited owing to few field constraints on key parameters, and computational difficulties expanding the framework to two-dimensions. To address this knowledge gap, we performed a series of field experiments on natural hillslopes to inform a simple particle-based model of hillslope sediment transport. We compiled the distribution of average velocity and transport distance for over 300 stones ranging in diameter from 2-10 cm using a video camera and laser range-finder. To characterize surface roughness, we used a tripod-based laser scanner to generate a 1 cm-resolution digital elevation model of each 30 m long hillslope. We find that hillslope travel distance follows a heavy-tailed distribution that varies systematically with the ratio of particle diameter to roughness height, in general agreement to published laboratory experiments. Mean particle velocity ranges from 1-3 m/s and scales weakly with distance traveled. Our modeling exercise reveals three key effects that should be included in any treatment of steep hillslope evolution: (1) there is a strong grain-size and surface roughness dependence on sediment transport distance, (2) sediment storage on slopes steeper than the angle of repose is possible due to vegetation or topographic roughness, and (3

  9. Check dams effects on sediment transport in steep slope flume

    NASA Astrophysics Data System (ADS)

    Piton, Guillaume; Recking, Alain

    2014-05-01

    Depending on many influences (geology, relief, hydrology, land use, etc.) some mountainous watershed are prone to cause casualties and facilities damages. Large amounts of sediments episodically released by torrents are often the biggest problem in torrent related hazard mitigation. Series of transversal structures as check dams and ground sills are often used in the panel of risk mitigation technics. A large literature exits on check dams and it mainly concerns engineering design, e.g. toe scouring, stability stress diagram, changes in upper and lower reaches equilibrium slopes. Check dams in steep slope rivers constitute fixed points in the bed profile and prevent general bed incision. However their influence on sediment transport once they are filled is not yet clear. Two flume test campaigns, synthetize in Table 1, were performed to investigate this question: Table 1 : experiment plan Run (duration) Ref1 (50h)CD1a (30h)CD1b (30h)Ref2 (92h)CD2 (18h) Solid feeding discharge (g.s^-1) 44 44 44 60 60 Number of check dams none 1 3 none 2 A nearly 5-m-long, 10-cm-wide and 12%-steep flume was used. The water discharge was set to 0,55 l/s in all runs. A mixture of poorly sorted natural sediments with diameters between 0.8 and 40 mm was used. An open solid-discharge-feeding circuit kept the inlet sediment flux constant during all experiments. As both feeding rates did not present variation, changes in outlet solid discharge were assumed to be due to bed variations in the bed storage. We observed strong fluctuations of solid flux and slope in each reaches of all runs between: (i) steep aggradating armoured bed and (ii) less steep and finer bed releasing bedload sheets during erosion events and inducing bedload pulses. All experiments showed consistent results: transported volume associated with erosion event decreased with the length between two subsequent check dams. Solid transversal structures shorten the upstream erosion-propagation and avoid downstream change in the

  10. Orographic Precipitation Changes and Shallow Landslide-Derived Sediment in Steep Landscapes

    NASA Astrophysics Data System (ADS)

    Bellugi, D. G.; O'Gorman, P. A.; Perron, J. T.; Milledge, D.

    2014-12-01

    Rainfall-triggered shallow landslides are both a hazard and a major source of sediment in steep landscapes. Extreme precipitation events are expected to change under climate warming, but we have limited understanding of their effect on the relative abundance, size, and spatial distribution of landslides. In particular, changes in orographic precipitation may alter landslide distributions in steep landscapes. Recent theory suggests a significant downwind shift in orographic precipitation under a warming climate, causing larger fractional changes on leeward than on windward slopes. This may prove particularly relevant on the west coast of the USA where mountain ranges are oriented perpendicular to the moisture-laden prevailing winds coming from the Pacific. We analyze precipitation data from regional climate models (NARCCAP) under a high-end emissions scenario (IPCC A2). Preliminary results show that mean winter precipitation over the contiguous United States increases by roughly 2% over both low and high elevation regions in the simulations between the periods 1971-2000 to 2041-2070, but much larger fractional changes (~ triple) are found on leeward slopes. For the same periods, we find that extremes have greater fractional changes in intensity than the mean, and that these changes increase with return period. Similar trends emerge in the West Coast, but with bigger differences between windward and leeward slopes, which increase with return period. Moreover, while leeward increases are large for 30-year events (14%-19%), they are marked even for 2-year events (7-12%). This could significantly impact the frequency and magnitude of shallow landslides in steep landscapes affected by orographic precipitation. We test this hypothesis by applying a new catchment-scale model, which predicts both landslide location and size, to an intensively investigated study site in the Oregon Coast Range, where a ten-year landslide inventory has been mapped onto high

  11. Using repeat lidar to estimate sediment transport in a steep stream

    NASA Astrophysics Data System (ADS)

    Anderson, Scott; Pitlick, John

    2014-03-01

    Sediment fluxes in steep mountain streams remain difficult to quantify, despite their importance in geomorphology, ecology, and hazard analysis. In this work, aerial lidar surveys, acquired in 2002, 2008, and 2012, are used to quantify such fluxes in Tahoma Creek, a proglacial stream on Mount Rainier, Washington. As these surveys encompass all coarse sediment sources in the basin, we are able to translate geomorphic change into total bed material transport volumes for the time steps between surveys. By assuming that the relationship between daily sediment transport and daily mean discharge is of the form Qs=a(Q-Qc)b, our two observed total loads and estimates of daily mean discharge allow us to numerically solve for values of a and b to create a bed material sediment rating curve. Comparisons of our transport estimates with sediment deposition in a downstream reservoir indicate that our transport estimates and derived rating curve are reasonable. The method we present thus represents a plausible means of estimating transport rates in energetic settings or during extreme events, applicable whenever at least two cumulative sediment loads and the driving hydrology are known. We use these results to assess the performance of several bed load transport equations. The equations generally overpredict transport at low to moderate flows but significantly underpredict transport rates during an extreme event. Using a critical shear stress value appropriate for steep streams improves agreement at lower flows, whereas a shear-partitioning technique accounting for form drag losses significantly underpredicts transport at all flows.

  12. Magnetic Field Disorder and Faraday Effects on the Polarization of Extragalactic Radio Sources

    NASA Astrophysics Data System (ADS)

    Lamee, Mehdi; Rudnick, Lawrence; Farnes, Jamie S.; Carretti, Ettore; Gaensler, B. M.; Haverkorn, Marijke; Poppi, Sergio

    2016-09-01

    We present a polarization catalog of 533 extragalactic radio sources that have a 2.3 GHz total intensity above 420 mJy from the S-band Polarization All Sky Survey, S-PASS, with corresponding 1.4 GHz polarization information from the NRAO VLA Sky Survey, NVSS. We studied the selection effects and found that fractional polarization, π, of radio objects at both wavelengths depends on the spectral index, the source magnetic field disorder, the source size, and depolarization. The relationship between depolarization, spectrum, and size shows that depolarization occurs primarily in the source vicinity. The median {π }2.3 of resolved objects in NVSS is approximately two times larger than that of unresolved sources. Sources with little depolarization are ∼2 times more polarized than both highly depolarized and re-polarized sources. This indicates that intrinsic magnetic field disorder is the dominant mechanism responsible for the observed low fractional polarization of radio sources at high frequencies. We predict that number counts from polarization surveys will be similar at 1.4 GHz and at 2.3 GHz, for fixed sensitivity, although ∼10% of all sources may currently be missing because of strong depolarization. Objects with {π }1.4≈ {π }2.3≥slant 4 % typically have simple Faraday structures, so they are most useful for background samples. Almost half of flat-spectrum (α ≥slant -0.5) and ∼25% of steep-spectrum objects are re-polarized. Steep-spectrum, depolarized sources show a weak negative correlation of depolarization with redshift in the range 0 < z < 2.3. Previous non-detections of redshift evolution are likely due the inclusion of re-polarized sources as well.

  13. Enhanced stochastic fluctuations to measure steep adhesive energy landscapes.

    PubMed

    Haider, Ahmad; Potter, Daniel; Sulchek, Todd A

    2016-12-13

    Free-energy landscapes govern the behavior of all interactions in the presence of thermal fluctuations in the fields of physical chemistry, materials sciences, and the biological sciences. From the energy landscape, critical information about an interaction, such as the reaction kinetic rates, bond lifetimes, and the presence of intermediate states, can be determined. Despite the importance of energy landscapes to understanding reaction mechanisms, most experiments do not directly measure energy landscapes, particularly for interactions with steep force gradients that lead to premature jump to contact of the probe and insufficient sampling of transition regions. Here we present an atomic force microscopy (AFM) approach for measuring energy landscapes that increases sampling of strongly adhesive interactions by using white-noise excitation to enhance the cantilever's thermal fluctuations. The enhanced fluctuations enable the recording of subtle deviations from a harmonic potential to accurately reconstruct interfacial energy landscapes with steep gradients. Comparing the measured energy landscape with adhesive force measurements reveals the existence of an optimal excitation voltage that enables the cantilever fluctuations to fully sample the shape and depth of the energy surface.

  14. Enhanced stochastic fluctuations to measure steep adhesive energy landscapes

    PubMed Central

    Haider, Ahmad; Potter, Daniel; Sulchek, Todd A.

    2016-01-01

    Free-energy landscapes govern the behavior of all interactions in the presence of thermal fluctuations in the fields of physical chemistry, materials sciences, and the biological sciences. From the energy landscape, critical information about an interaction, such as the reaction kinetic rates, bond lifetimes, and the presence of intermediate states, can be determined. Despite the importance of energy landscapes to understanding reaction mechanisms, most experiments do not directly measure energy landscapes, particularly for interactions with steep force gradients that lead to premature jump to contact of the probe and insufficient sampling of transition regions. Here we present an atomic force microscopy (AFM) approach for measuring energy landscapes that increases sampling of strongly adhesive interactions by using white-noise excitation to enhance the cantilever’s thermal fluctuations. The enhanced fluctuations enable the recording of subtle deviations from a harmonic potential to accurately reconstruct interfacial energy landscapes with steep gradients. Comparing the measured energy landscape with adhesive force measurements reveals the existence of an optimal excitation voltage that enables the cantilever fluctuations to fully sample the shape and depth of the energy surface. PMID:27911778

  15. Designing steep, sharp patterns on uniformly ion-bombarded surfaces

    PubMed Central

    Perkinson, Joy C.; Aziz, Michael J.; Brenner, Michael P.; Holmes-Cerfon, Miranda

    2016-01-01

    We propose and experimentally test a method to fabricate patterns of steep, sharp features on surfaces, by exploiting the nonlinear dynamics of uniformly ion-bombarded surfaces. We show via theory, simulation, and experiment that the steepest parts of the surface evolve as one-dimensional curves that move in the normal direction at constant velocity. The curves are a special solution to the nonlinear equations that arises spontaneously whenever the initial patterning on the surface contains slopes larger than a critical value; mathematically they are traveling waves (shocks) that have the special property of being undercompressive. We derive the evolution equation for the curves by considering long-wavelength perturbations to the one-dimensional traveling wave, using the unusual boundary conditions required for an undercompressive shock, and we show this equation accurately describes the evolution of shapes on surfaces, both in simulations and in experiments. Because evolving a collection of one-dimensional curves is fast, this equation gives a computationally efficient and intuitive method for solving the inverse problem of finding the initial surface so the evolution leads to a desired target pattern. We illustrate this method by solving for the initial surface that will produce a lattice of diamonds connected by steep, sharp ridges, and we experimentally demonstrate the evolution of the initial surface into the target pattern. PMID:27698147

  16. Computing nonhydrostatic shallow-water flow over steep terrain

    USGS Publications Warehouse

    Denlinger, R.P.; O'Connell, D. R. H.

    2008-01-01

    Flood and dambreak hazards are not limited to moderate terrain, yet most shallow-water models assume that flow occurs over gentle slopes. Shallow-water flow over rugged or steep terrain often generates significant nonhydrostatic pressures, violating the assumption of hydrostatic pressure made in most shallow-water codes. In this paper, we adapt a previously published nonhydrostatic granular flow model to simulate shallow-water flow, and we solve conservation equations using a finite volume approach and an Harten, Lax, Van Leer, and Einfeldt approximate Riemann solver that is modified for a sloping bed and transient wetting and drying conditions. To simulate bed friction, we use the law of the wall. We test the model by comparison with an analytical solution and with results of experiments in flumes that have steep (31??) or shallow (0.3??) slopes. The law of the wall provides an accurate prediction of the effect of bed roughness on mean flow velocity over two orders of magnitude of bed roughness. Our nonhydrostatic, law-of-the-wall flow simulation accurately reproduces flume measurements of front propagation speed, flow depth, and bed-shear stress for conditions of large bed roughness. ?? 2008 ASCE.

  17. A Giant Metrewave Radio Telescope search for associated H I 21 cm absorption in high-redshift flat-spectrum sources

    NASA Astrophysics Data System (ADS)

    Aditya, J. N. H. S.; Kanekar, Nissim; Kurapati, Sushma

    2016-02-01

    We report results from a Giant Metrewave Radio Telescope search for `associated' redshifted H I 21 cm absorption from 24 active galactic nuclei (AGNs), at 1.1 < z < 3.6, selected from the Caltech-Jodrell Bank Flat-spectrum (CJF) sample. 22 out of 23 sources with usable data showed no evidence of absorption, with typical 3σ optical depth detection limits of ≈0.01 at a velocity resolution of ≈30 km s-1. A single tentative absorption detection was obtained at z ≈ 3.530 towards TXS 0604+728. If confirmed, this would be the highest redshift at which H I 21 cm absorption has ever been detected. Including 29 CJF sources with searches for redshifted H I 21 cm absorption in the literature, mostly at z < 1, we construct a sample of 52 uniformly selected flat-spectrum sources. A Peto-Prentice two-sample test for censored data finds (at ≈3σ significance) that the strength of H I 21 cm absorption is weaker in the high-z sample than in the low-z sample; this is the first statistically significant evidence for redshift evolution in the strength of H I 21 cm absorption in a uniformly selected AGN sample. However, the two-sample test also finds that the H I 21 cm absorption strength is higher in AGNs with low ultraviolet or radio luminosities, at ≈3.4σ significance. The fact that the higher luminosity AGNs of the sample typically lie at high redshifts implies that it is currently not possible to break the degeneracy between AGN luminosity and redshift evolution as the primary cause of the low H I 21 cm opacities in high-redshift, high-luminosity AGNs.

  18. Development of the MICROMEGAS detector for measuring the energy spectrum of alpha particles by using a 241Am source

    NASA Astrophysics Data System (ADS)

    Kim, Do Yoon; Ham, Cheolmin; Shin, Jae Won; Park, Tae-Sun; Hong, Seung-Woo; Andriamonje, Samuel; Kadi, Yacine; Tenreiro, Claudio

    2016-05-01

    We have developed MICROMEGAS (MICRO MEsh GASeous) detectors for detecting a particles emitted from an 241Am standard source. The voltage applied to the ionization region of the detector is optimized for stable operation at room temperature and atmospheric pressure. The energy of a particles from the 241Am source can be varied by changing the flight path of the a particle from the 241Am source. The channel numbers of the experimentally-measured pulse peak positions for different energies of the a particles are associated with the energies deposited by the alpha particles in the ionization region of the detector as calculated by using GEANT4 simulations; thus, the energy calibration of the MICROMEGAS detector for a particles is done. For the energy calibration, the thickness of the ionization region is adjusted so that a particles may completely stop in the ionization region and their kinetic energies are fully deposited in the region. The efficiency of our MICROMEGAS detector for a particles under the present conditions is found to be ~97.3%.

  19. Lead distribution and possible sources along vertical zone spectrum of typical ecosystems in the Gongga Mountain, eastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Luo, Ji; Tang, Ronggui; Sun, Shouqin; Yang, Dandan; She, Jia; Yang, Peijun

    2015-08-01

    A total of 383 samples from soil, plant, litterfall and precipitation in four typical ecosystems of Gongga Mountain were collected. Pb concentrations of samples were measured and analyzed. The results showed mean Pb concentrations in different soil layers were in the order of O > A > C, and mean Pb concentrations of the aboveground parts of plant was 3.60 ± 2.54 mg kg-1, with the minimum value of 0.77 mg kg-1 and the maximum value of 10.90 mg kg-1. Pb concentrations in soil's O-horizon and A-horizon showed a downward trend with increasing elevation (the determination coefficient R2 was 0.9478, 0.7918 and 0.9759 respectively). In contrast to other soil layers, the level of Pb concentrations in O-horizon (incomplete decomposition) was significantly high. Litterfall decomposition, atmospheric deposition and the unique climate could be main factors leading high Pb accumulation in soil's O-horizon. What's more, significant correlation (R2 = 0.8126, P < 0.05) was found between Pb concentrations in fine roots and soil's A-horizon confirms that fine roots could adsorb and accumulate Pb materials in soil. In general, the fact that Pb inputted into the typical ecosystems in the Gongga Mountain via long-range transportation and deposition of the atmosphere from external Pb sources could be confirmed by the HYSPLIT model and the ratio of CPb/CAl in plants (leaves) and CPb/CAl in litterfall. The mining activities and increasing anthropogenic activities (tourism development) could be main sources of Pb in this area. In order to better understand Pb sources and eco-risks of these typical ecosystems, litterfall decomposition characteristics, biomass of productivity of forest ecosystem, Pb isotopic tracing among air mass, twigs, leaves, litterfall and O-horizon soil in this vertical belt should also be taken into consideration.

  20. Comprehensive evaluation of high-steep slope stability and optimal high-steep slope design by 3D physical modeling

    NASA Astrophysics Data System (ADS)

    Lai, Xing-ping; Shan, Peng-fei; Cai, Mei-feng; Ren, Fen-hua; Tan, Wen-hui

    2015-01-01

    High-steep slope stability and its optimal excavation design in Shuichang open pit iron mine were analyzed based on a large 3D physical simulation technique. An optimal excavation scheme with a relatively steeper slope angle was successfully implemented at the northwest wall between Nos. 4 and 5 exploration lines of Shuichang Iron Mine, taking into account the 3D scale effect. The physico-mechanical properties of rock materials were obtained by laboratory tests conducted on sample cores from exploration drilling directly from the iron mine. A porous rock-like composite material was formed for the model, and the mechanical parameters of the material were assessed experimentally; specifically, the effect of water on the sample was quantitatively determined. We adopted an experimental setup using stiff modular applied static loading to carry out a visual excavation of the slope at a random depth. The setup was equipped with acoustic emission (AE) sensors, and the experiments were monitored by crack optical acquirement, ground penetrating radar, and close-field photogrammetry to investigate the mechanisms of rock-mass destabilization in the high-steep slope. For the complex study area, the model results indicated a clear correlation between the model's destabilization resulting from slope excavation and the collected monitoring information. During the model simulation, the overall angle of the slope increased by 1-6 degrees in different sections. Dramatically, the modeled excavation scheme saved over 80 million tons of rock from extraction, generating enormous economic and ecological benefits.

  1. Parameterization of the sediment transport in steep channels with boulders

    NASA Astrophysics Data System (ADS)

    Ghilardi, Tamara; Franca, Mário J.; Schleiss, Anton

    2015-04-01

    The presence of large relatively immobile boulders in steep mountain rivers is generally not taken into account in the development of equations to predict the bedload, leading to overestimates of the bedload rate by several times when applied to mountain rivers. Sediment transport in steep channels with boulders is herein investigated using 41 laboratory experiments carried out on a steep (longitudinal inclination of 6.7 to 13%), 8 m long (7 m usable) and 0.25 m wide, tilting flume. The experiments were made for varying flume slopes and boulder configurations (combination of boulder dimensionless distance and diameter), and for several sediment supply conditions. 35 experiments are made with boulders and six experiments without boulders. Boulders are herein defined as elements that although not transported by the flow, may move several times their diameter during experiments, mainly due to the scour holes formed around them. Water and poorly sorted sediments are constantly supplied at the flume inlet. Bedload at the channel downstream section, bulk flow velocities and morphological parameters are measured regularly during the experiments. The poorly sorted sediments (d50=9.3 mm, d65=11.9 mm, d30=7.1 mm, d84=16.6 mm, and d90=19.0 mm) are constantly fed into the system by a calibrated sediment feeder situated upstream, and recirculated during the experiments. The experiments show that the sediment transport capacity clearly decreases with the dimensionless boulder distance and is better estimated in terms of critical discharge for incipient motion of mobile sediments than in terms of critical bed shear stress. The channel longitudinal slope shows the strongest impact on the transport capacity, namely in what concerns the critical discharge for beginning of motion. In addition, it is also shown that the sediment transport decreases with boulder density. A sediment transport formula based on excess discharge relative to a critical value, which depends not only on the

  2. HOTSPUR progress report: neutron source spectrum characterization, and /sup 6/Li(n,x. cap alpha. ) and /sup 7/Li(n,x. cap alpha. ) cross section determination

    SciTech Connect

    Goldberg, E.; Haight, R.

    1984-04-02

    As a prerequisite to high accuracy measurements involving the bulk configuration of /sup 6/LiD we must have a good grasp of the details of the RTNS-I neutron source energy spectrum. Experiments to this end involving neutron yield vs deuteron energy, ratios of foil activation of selected elements, and pulse height distributions of a Si surface barrier detector are described. With this knowledge, the /sup 4/He-production cross sections for /sup 6/Li and /sup 7/Li are found experimentally to be 0.512b and 0.336b, respectively, at anti E/sub N/ = 15.0 MeV in free-field geometry. 14 references.

  3. Dosimetry in steep dose-rate gradient radiation fields: A challenge in clinical applications

    NASA Astrophysics Data System (ADS)

    Massillon-JL, G.

    2010-12-01

    The fundamental goal of radiotherapy is to reduce the damage to normal tissue and optimize the dose to the tumor with an associated high probability of cure. Because of this, an accurate and precise knowledge of the radiation dose distribution delivered around the tumor volume during radiotherapy treatments such as stereotactic radiosurgery, intensity modulated radiotherapy or brachytherapy with low-energy X-ray and beta particle sources is of great importance. However, in each of these radiation fields, there exists a steep dose-rate gradient which makes it very difficult to perform accurate dose measurements. In this work, the physics phenomena involved in the energy absorption for each of these situations are discussed, and a brief revision of what the Medical Physics community is doing is presented.

  4. Classification and analysis of corn steep liquor by UPLC/Q-TOF MS and HPLC.

    PubMed

    Xiao, Xue; Hou, Yuanyuan; Liu, Yang; Liu, Yanjie; Zhao, Hongzhi; Dong, Linyi; Du, Jun; Wang, Yiming; Bai, Gang; Luo, Guoan

    2013-03-30

    Corn steep liquor (CSL), an important raw material with high nutritional value, serves as a nitrogen source in the fermentation industry. The CSL quality directly affects the yield and quality of fermentation products. In this work, a fingerprinting technique was used to identify the potential markers of CSL. Forty-two CSL samples from different manufacturers were profiled by ultra-performance liquid chromatography with tandem quadrupole time-of-flight mass spectrometry. Sixteen compounds, almost all of which were amino acids and their derivatives, were considered as the potential markers. Then, o-phthalaldehyde-9-fluorenylmethyl chloroformate precolumn derivatization by high-performance liquid chromatography was performed to identify the free amino acids in CSL. Principal component analysis (PCA) was used to distinguish among the samples from different manufacturers. The results demonstrated that the fingerprinting technique combined with PCA analysis was a powerful tool for determining the CSL quality.

  5. Dosimetry in steep dose-rate gradient radiation fields: A challenge in clinical applications

    SciTech Connect

    Massillon-JL, G.

    2010-12-07

    The fundamental goal of radiotherapy is to reduce the damage to normal tissue and optimize the dose to the tumor with an associated high probability of cure. Because of this, an accurate and precise knowledge of the radiation dose distribution delivered around the tumor volume during radiotherapy treatments such as stereotactic radiosurgery, intensity modulated radiotherapy or brachytherapy with low-energy X-ray and beta particle sources is of great importance. However, in each of these radiation fields, there exists a steep dose-rate gradient which makes it very difficult to perform accurate dose measurements. In this work, the physics phenomena involved in the energy absorption for each of these situations are discussed, and a brief revision of what the Medical Physics community is doing is presented.

  6. An important erosion process on steep burnt hillslopes

    NASA Astrophysics Data System (ADS)

    Langhans, Christoph; Nyman, Petter; Noske, Philip; Lane, Patrick; Sheridan, Gary

    2016-04-01

    Steep forested hillslopes often display a high degree of armouring where diffusive erosion processes preferentially remove the fine fraction of the surface soil. High infiltration capacities, hydraulic resistance to overland flow and physical anchoring by cover plants and litter mean that even the most extreme rainfall events usually do not erode the armouring substantially. We argue that fire (wild or planned) is essential to the mobilization and transport of the armouring by increasing the rates of overland flow and decreasing trapping opportunities. We present evidence of the types of erosion that lead to the stripping of the surface armouring using post-event surveys and high-rate overland flow experiments. The type of erosion depends on the relative abundance of non-cohesive surface material to overland flow, but we found that a particular type of transport dominates that has no representation in current erosion models: On steep slopes overland flow can lead to incipient motion of individual stones that transfer their momentum to other stones leading to a rapid mobilization of the whole non-cohesive, armoured surface layer. Once in motion, the layer quickly separates out into a granular flow front and liquefied body, akin to debris flows in channels. Depending on the size of the event, these hillslope debris flows (HDF) either get trapped or enter into the channel, stripping the hillslope of most armouring on their way. They provide channels with the material and shear stress needed to erode into the channel bed, increasing the risk of channel debris flows. We present a simple physical model of HDF initiation, movement, and possible re-mobilization on hillslopes that was derived from debris flow theory. Understanding this process, its frequency, and magnitude are important for assessing the role of fire in landscape evolution and risk to humans through debris flow impacts.

  7. De-icers derived from corn steep water.

    PubMed

    Yang, Byung Yun; Montgomery, Rex

    2003-12-01

    Corn steep water (CSW) and other byproducts derived from fermentations and sugar productions are presently forming the base of compositions for de-icing and anti-icing materials. Since the de-icing and anti-icing values are in part a colligative property, increase in the molar concentration of ionic species has been frequently necessary to decrease further the freezing point of this byproducts stream. In the present study this has been achieved by the generation of biodegradable organic acid salts in situ, without the use of chloride or other inorganic salts, by the alkaline degradation of reducing sugars added to corn steep water, which alone is not an efficient de-icer. Reducing sugars, such as glucose, react with alkali metal hydroxides to produce principally hydroxy carboxylic acids that react with the alkali metal hydroxide to form a mixture of organic acid salts. The ionic strength of the resulting solution is increased since each sugar molecule produces nearly two acid molecules upon degradation. The ionic strength necessary to achieve the desired freezing point depression is determined by the amount and concentration of the alkali metal hydroxide used, with the necessary counter anions being derived from the degradation of the reducing sugar. The amount of the sugar used is that required to result in a near to neutral final solution. The well-known anti-corrosive property of CSW is used in the de-icer preparations, either by conducting the alkaline degradation of the sugar in this medium, or by using water for the degradation of the sugar followed by dilution of the resulting solution with CSW to adjust the viscosity of the final solution to meet the requirements for spraying. The monovalent metal hydroxides are more efficient in producing de-icer solutions than the divalent metal hydroxides.

  8. Chandra Discovery of Intervening, Local and Intrinsic Highly Ionized Absorption in an extremely bright high resolution X-ray spectrum of an Extragalactic Source

    NASA Astrophysics Data System (ADS)

    Nicastro, F.; Elvis, M.; Fang, T.; Mathur, S.; Siemiginowska, A.; Zezas, A.

    2003-03-01

    In this contribution we present the brightest high resolution X-ray spectrum ever taken for an extragalactic source. Following our ToO request, Chandra observed the blazar Mkn 421 (z=0.03) during an exceptionally high-luminosity flare. The observation lasted about 100 ks, during which the source reached a flux level of > 0.1 Crab in the 0.5-2 keV band This allowed us to collect 4.2 million counts in the 1st-order ACIS-LETG spectrum of Mkn 421, and more than 3000 counts per resolution elements at the rest frame wavelength of the OVII Kα resonant transitions (21.6 Å). A forest of very weak (EW=3.1-10 mÅ) resonant absorption lines is detected from the rest frame wavelength of the OVII Kα all the way down to the position of the OVII Kα line at the source redshift. We identify these lines as due to: (a) Local Group Warm-Hot Intergalactic Medium (WHIM) absorption, (b) intervening WHIM absorption at redshifts z=0.01 (associated with faint H Lyα absorption) and z=0.025, and (c) intrinsic source absorption. The strongest of these systems is associated with the local WHIM first discovered along the line of sight to PKS 2155-304 (Nicastro et al., 2002, 2003), and now observed (always with consistent gas properties) along all the lines of sight for which Chandra high resolution spectra with sufficient signal to noise ratio are available. The faintest systems (probing OVII column densities as low as 1015 cm-2) are those identified as due to the two intervening WHIM systems. If both these identification are correct this discovery implies a number of intervening OVII WHIM systems per unit redshift of dN/dz(NOVII>1015) = 75, about 3-4 times larger than the corresponding number estimated for OVI systems in the local Universe (down to OVI EW of 60 mÅ). The WHIM baryon fraction implied depends slightly on the ionization correction applied, and ranges between 40 % and 60 % of the total baryons at z<2, so confirming hydrodynamical simulation predictions and accounting for all of

  9. Cooperative Three-Robot System for Traversing Steep Slopes

    NASA Technical Reports Server (NTRS)

    Stroupe, Ashley; Huntsberger, Terrance; Aghazarian, Hrand; Younse, Paulo; Garrett, Michael

    2009-01-01

    Teamed Robots for Exploration and Science in Steep Areas (TRESSA) is a system of three autonomous mobile robots that cooperate with each other to enable scientific exploration of steep terrain (slope angles up to 90 ). Originally intended for use in exploring steep slopes on Mars that are not accessible to lone wheeled robots (Mars Exploration Rovers), TRESSA and systems like TRESSA could also be used on Earth for performing rescues on steep slopes and for exploring steep slopes that are too remote or too dangerous to be explored by humans. TRESSA is modeled on safe human climbing of steep slopes, two key features of which are teamwork and safety tethers. Two of the autonomous robots, denoted Anchorbots, remain at the top of a slope; the third robot, denoted the Cliffbot, traverses the slope. The Cliffbot drives over the cliff edge supported by tethers, which are payed out from the Anchorbots (see figure). The Anchorbots autonomously control the tension in the tethers to counter the gravitational force on the Cliffbot. The tethers are payed out and reeled in as needed, keeping the body of the Cliffbot oriented approximately parallel to the local terrain surface and preventing wheel slip by controlling the speed of descent or ascent, thereby enabling the Cliffbot to drive freely up, down, or across the slope. Due to the interactive nature of the three-robot system, the robots must be very tightly coupled. To provide for this tight coupling, the TRESSA software architecture is built on a combination of (1) the multi-robot layered behavior-coordination architecture reported in "An Architecture for Controlling Multiple Robots" (NPO-30345), NASA Tech Briefs, Vol. 28, No. 10 (October 2004), page 65, and (2) the real-time control architecture reported in "Robot Electronics Architecture" (NPO-41784), NASA Tech Briefs, Vol. 32, No. 1 (January 2008), page 28. The combination architecture makes it possible to keep the three robots synchronized and coordinated, to use data

  10. Time-resolved electronic Raman spectrum of terbium aluminum garnet excited with visible and UV laser sources

    NASA Astrophysics Data System (ADS)

    Myslynski, P.; Koningstein, J. A.

    1987-05-01

    Excitation profiles for the intensities of electronic Raman transitions between crystal field components of the 7F 6 and 7F 5 manifolds of terbium aluminum garnet are recorded for excitation in the spectral region where absorption bands due to levels of the 5D 4 manifold occur. The intensities of the electronic transitions are not enhanced which is thought to be caused by the small values of electric dipole matrix elements of the resonating electronic states in comparison to the values of such elements to other intermediate states which occur in the expression for the scattering tensor. Fluorescence from the 5D 4 levels is induced and resonance fluorescence are time resolved with respect to the Raman transitions. We report electronic Raman transitions excited with the 308.0 nm line of an XeCl excimer laser. As opposed to excitation with visible laser sources, transitions are recorded which terminate on all the crystal field levels of the 7F 5…0 levels. In addition, fluorescence from 5D 3 to the ground state of terbium aluminum garnet is also observed.

  11. Numerical calculations of spectral turnover and synchrotron self-absorption in CSS and GPS radio sources

    NASA Astrophysics Data System (ADS)

    Jeyakumar, S.

    2016-06-01

    The dependence of the turnover frequency on the linear size is presented for a sample of Giga-hertz Peaked Spectrum and Compact Steep Spectrum radio sources derived from complete samples. The dependence of the luminosity of the emission at the peak frequency with the linear size and the peak frequency is also presented for the galaxies in the sample. The luminosity of the smaller sources evolve strongly with the linear size. Optical depth effects have been included to the 3D model for the radio source of Kaiser to study the spectral turnover. Using this model, the observed trend can be explained by synchrotron self-absorption. The observed trend in the peak-frequency-linear-size plane is not affected by the luminosity evolution of the sources.

  12. Quantification of fluvial bedload transport in glacier-connected steep mountain catchments in western Norway

    NASA Astrophysics Data System (ADS)

    Beylich, Achim A.; Laute, Katja

    2015-04-01

    Contemporary fluvial bedload transport rates are still very difficult to measure and, as a result of this, in many sites only quantitative data on fluvial suspended and solute transport are included in sediment budget studies carried out for defined drainage basin systems. During the years 2010-2013 detailed field measurements with portable impact sensors as a non-invasive technique for indirectly determining fluvial bedload transport intensity were conducted in two instrumented drainage basin systems (Erdalen and Bødalen) in the fjord landscape in western Norway. The collected impact sensor field data were calibrated with laboratory flume experiments, and the data from the impact sensor field measurements and the flume experiments were combined with field data from continuous discharge monitoring, repeated surveys of channel morphometry and sediment texture, particle tracer measurements, Helley-Smith samplings, underwater video filming and biofilm analyses. The combination of methods and techniques applied provides insights into the temporal variability and intensity of fluvial bedload transport in the selected mountain streams of both drainage basin systems. The conducted analysis of fluvial bedload dynamics in different defined subsystems of Erdalen (79.5 km2) and Bødalen (60.1 km2) provides information on (i) detectable relevant sediment sources, (ii) instream channel storage of bedload material, (iii) spatiotemporal variability and controls of bedload transport rates and bedload yields, and (iv) the absolute and relative importance of fluvial bedload transport within the sedimentary budgets of these steep cold climate mountain catchments. Rockfalls, snow avalanches, stream channel bank erosion, and fluvial transfers through small tributaries draining slope systems are relevant sediment sources for fluvial bedload transport in the main stream channels, whereas the main outlet glaciers in both catchment systems are not of importance as all bedload material

  13. On the determination of the cosmic infrared background radiation from the high-energy spectrum of extragalactic gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Slavin, Jonathan

    1994-01-01

    In a recent paper Stecker, De Jager, & Salamon have suggested using the observed approximately MeV to TeV spectra of extragalactic gamma-ray sources as probes of the local density of the cosmic infrared background radiation (CIBR) and have subsequently claimed a first possible measurement of the CIBR from the analysis of the gamma-ray spectrum of Mrk 421 (De Jager, Stecker, & Salamon). The CIBR from normal galaxies consists of two components: a stellar emission component (CIBRs), and a thermal dust emission component (CIBRd). Photons with energies in the approximately 0.1-2 TeV range interact primarily with the CIBRs, whereas interactions with CIBRd dominate the absorption of photons in the approximately 2-100 TeV energy range. SDS 92 and DSS94 considered only the interaction of the gamma-rays with the dust emission component of the CIBR. We present here an improved analysis of the absorption of extragalactic TeV gamma rays by the CIBR, taking the dual nature of its origin into account. Applying the analysis to the observed gamma-ray spectrum of Mrk 421, a BL Lac object at z = 0.031, we find agreement with DSS94 tentative evidence for absorption by the CINRs. Our analysis therefore limits the detection of the CIBR to the approximately 15-40 micron wavelength regime which, considering the uncertainties in the highest energy (greater than 4 TeV) data and ion the possibility of absorption inside the source, many turn out to be an upper limit on its energy density. At shorter wavelengths (lambda approximately = 1-15 microns), where the gamma-ray interactions are dominated by the CIBRs, our analysis definitely yields only an upper limit on the energy density of the CIBR. In contrast, DSS94 have claimed a possible first measurement of the CIBR over the entire 1-120 micron wavelength region. The upper limit on the CIBRs and tentative detection of the CIBRd are consistent with normal galaxies contributing most of the energy to the CIBR, and constrain the contribution of

  14. Ice motion and seismic activity on a steep temporate glacier tongue

    NASA Astrophysics Data System (ADS)

    Dalban Canassy, Pierre; Faillettaz, Jerome; Funk, Martin

    2010-05-01

    Ice motion and seismic activity on a steep temporate glacier (Triftgletscher, Bernese Alps, Switzerland) Pierre Dalban Canassy*, Jerome Faillettaz* and Martin Funk* * Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, CH-8092 Zurich, Switzerland (dalban@vaw.baug.ethz.ch) In the last 15 years Triftgletscher (Bernese Alps, Switzerland) has substantially retreated (several hundreds of meters) from the riegel and a proglacial lake containing 6.106 m3 water has been formed in the glacier forefield. Because of the glacier retreat, especially the thinning of the lower flat tongue, the stability of the steep section behind it is affected. The consequence is that the likelihood of large ice avalanches starting from the steep section will increase. The recent intensive glacier thinning in the lower tongue area of 6-10 m.a-1 has even worsened the situation because the runout path of the ice avalanches has become steeper. Ice avalanches with several millions of m3 triggering impulse waves by plunguing into the lake can be the consequence. The aim of our study is to improve the understanding of the mechanisms leading to such instabilities and to develop a predictive method based on both seismic and photogrammetric surveys. The seismic recording is performed with help of 3 geophones installed on the rock on both sides of the serac fall allowing a continuous record. We are able to highlight seismic events by applying an automatic detection procedure, to locate their sources and also to evaluate the released energy of each detected icequake. The most part of these events are due to crack openings and falls of ice chunks, but we could also isolate specific events corresponding to stick-slip motions. The latter seem to play a significant role in the destabilization of the ice mass and represent valuable precursors to break-off episodes. The 2D picture analysis is achieved by analysing photographs taken every day at the same time by an automatic camera installed in

  15. Relative roughness controls on incipient sediment motion in steep channels

    NASA Astrophysics Data System (ADS)

    Prancevic, J.; Lamb, M. P.; Fuller, B. M.

    2012-12-01

    For over eight decades, researchers have noted an appreciable increase in the nondimensional shear stress (Shields number) at initiation of fluvial bedload transport with increasing bed slope. The precise cause of the trend, however, is obscured by the covariance of several factors with increased slope: a greater downstream component of the gravity acting on the grains and fluid, changes in bed morphology, increased grainsize relative to the channel width that may lead to grain bridging, and increased grainsize relative to flow depth (relative roughness) that may change flow hydraulics and particle buoyancy. Here, we report on ongoing laboratory experiments spanning a wide range of bed slopes (2% to 67%) designed to isolate these variables and determine the true cause of heightened critical Shields numbers on steep slopes. First, we eliminated bed morphology as a factor by using only planar beds. To investigate the effect of grain bridging, we used two different channel widths, representing width-to-grainsize ratios of 23:1 and 9:1. Finally, to separate the effects of slope from relative roughness, we compared incipient motion conditions for acrylic particles (submerged specific gravity of 0.15) to natural siliciclastic gravel (submerged specific gravity of 1.65). Different particle densities allowed us to explore incipient motion as a function of relative roughness, independent of channel slope, because lighter particles move at shallower flow depths than heavier ones of the same size. Results show that both materials exhibit a positive trend between bed slope and critical Shields number despite the existence of planar beds for all slopes. Furthermore, changing the grainsize-to-width ratio had a negligible effect on this trend. For all slopes, the critical Shields number for bedload transport was higher for the acrylic particles than for gravel, indicating that relative roughness has a strong control on incipient sediment motion independent of channel slope. These

  16. Measuring noise equivalent irradiance of a digital short-wave infrared imaging system using a broadband source to simulate the night spectrum

    NASA Astrophysics Data System (ADS)

    Green, John R.; Robinson, Timothy

    2015-05-01

    There is a growing interest in developing helmet-mounted digital imaging systems (HMDIS) for integration into military aircraft cockpits. This interest stems from the multiple advantages of digital vs. analog imaging such as image fusion from multiple sensors, data processing to enhance the image contrast, superposition of non-imaging data over the image, and sending images to remote location for analysis. There are several properties an HMDIS must have in order to aid the pilot during night operations. In addition to the resolution, image refresh rate, dynamic range, and sensor uniformity over the entire Focal Plane Array (FPA); the imaging system must have the sensitivity to detect the limited night light available filtered through cockpit transparencies. Digital sensor sensitivity is generally measured monochromatically using a laser with a wavelength near the peak detector quantum efficiency, and is generally reported as either the Noise Equivalent Power (NEP) or Noise Equivalent Irradiance (NEI). This paper proposes a test system that measures NEI of Short-Wave Infrared (SWIR) digital imaging systems using a broadband source that simulates the night spectrum. This method has a few advantages over a monochromatic method. Namely, the test conditions provide spectrum closer to what is experienced by the end-user, and the resulting NEI may be compared directly to modeled night glow irradiance calculation. This comparison may be used to assess the Technology Readiness Level of the imaging system for the application. The test system is being developed under a Cooperative Research and Development Agreement (CRADA) with the Air Force Research Laboratory.

  17. Buoyant Turbulent Kinetic Energy Production in Steep-Slope Katabatic Flow

    NASA Astrophysics Data System (ADS)

    Oldroyd, Holly J.; Pardyjak, Eric R.; Higgins, Chad W.; Parlange, Marc B.

    2016-12-01

    We develop several critical concepts that should be considered when interpreting, modelling and designing future experiments for flows over sloping terrain. Vertical buoyancy fluxes in katabatic flows can be positive and a source of turbulent kinetic energy (TKE) despite the statically stable, thermal stratification that drives these flows. This phenomenon occurs when the ratio of along-slope to slope-normal kinematic heat fluxes is greater than the cotangent of the slope angle, suggesting a critical value of slope-angle steepness found in earlier studies. We provide field-data-based evidence that the along-slope heat flux may dominate the variables in this inequality, and therefore in generating buoyant TKE production or suppression over a steep slope. These data show the along-slope heat flux can be more variable and significantly larger in magnitude than the slope-normal component. The gradient Richardson number does not include the effects of the along-slope buoyancy; furthermore, none of the canonical stability parameters can properly reflect the TKE redistribution from turbulent transport divergence and the sink of TKE in cases of counter-gradient momentum fluxes, which we frequently observe near the peak of the katabatic jet. In such cases, canonical stability parameters inadequately represent the physical mechanisms associated with stability. These results have broad implications related to accurately modelling turbulence and surface exchanges over sloping terrain and illustrate the need to more thoroughly investigate the along-slope heat flux and its drivers, the meaning and definitions of stability, and the effects of non-local turbulent transport.

  18. A novel ultra steep dynamically reconfigurable electrostatically doped silicon nanowire Schottky Barrier FET

    NASA Astrophysics Data System (ADS)

    Singh, Sangeeta; Sinha, Ruchir; Kondekar, P. N.

    2016-05-01

    In this paper, an ultra steep, symmetric and dynamically configurable, electrostatically doped silicon nanowire Schottky FET (E-SiNW-SB-FET) based on dopant-free technology is investigated. It achieves the ultra steep sub-threshold slope (SS) due to the cumulative effect of weak impact-ionization induced positive feedback and electrostatic modulation of Schottky barrier heights at both source and drain terminals. It consists of axial nanowire heterostructure (silicide-intrinsic silicon-silicide) with three independent all-around gates, two gates are polarity control gates for dynamically reconfiguring the device polarity by modulating the effective Schottky barrier heights and a control gate switches the device ON and OFF. The most interesting features of the proposed structure are simplified fabrication process as the state-of-the-art for ion implantation and high thermal budget no more required for annealing. It is highly immune to process variations, doping control issues and random dopant fluctuations (RDF) and there are no mobility degradation issues related to high doping. A calibrated 3-D TCAD simulation results exhibit the SS of 2 mV/dec for n-type E-SiNW-SB-FET and 9 mV/dec for p-type E-SiNW-SB-FET for about five decades of current. Further, it resolves all the reliability related issues of IMOS as hot electron effects are no more limiting our device performance. It offers significant drive current of the order of 10-5-10-4 A and magnificently high ION/IOFF ratio of ∼108 along with the inherent advantages of symmetric device structure for its circuit realization.

  19. Radar scattering properties of steep-sided domes on Venus

    NASA Technical Reports Server (NTRS)

    Ford, Peter G.

    1994-01-01

    More than 100 quasi-circular steep-sided volcanic domes, with diameters ranging from 6 to 60 km, have been observed on the surface of Venus by the Magellan radar mapper. Assuming that they have the shape of a solidified high-viscosity Newtonian fluid, their radar scattering properties can be studied in detail from Magellan images, since a typical radar swath resolves each dome into several tens of thousands of measurements of radar cross section at incidence angles varying fom 15 deg to 55 deg. Through examination of 20 domes in detail, it appears that many of those situated on lava plains scatter radar in a manner that is indistinguishable from that of the surrounding material, suggesting that either (1) they were formed of a relatively high-density high-viscosity material, e.g., andesite, rather than a lower-density one, e.g., rhyolite or dacite; or (2) that their surfaces share a common origin with those of their surroundings, e.g., through in situ weathering or aeolian deposition.

  20. Geotechnical properties of cemented sands in steep slopes

    USGS Publications Warehouse

    Collins, B.D.; Sitar, N.

    2009-01-01

    An investigation into the geotechnical properties specific to assessing the stability of weakly and moderately cemented sand cliffs is presented. A case study from eroding coastal cliffs located in central California provides both the data and impetus for this study. Herein, weakly cemented sand is defined as having an unconfined compressive strength (UCS) of less than 100 kPa, and moderately cemented sand is defined as having UCS between 100 and 400 kPa. Testing shows that both materials fail in a brittle fashion and can be modeled effectively using linear Mohr-Coulomb strength parameters, although for weakly cemented sands, curvature of the failure envelope is more evident with decreasing friction and increasing cohesion at higher confinement. Triaxial tests performed to simulate the evolving stress state of an eroding cliff, using a reduction in confinement-type stress path, result in an order of magnitude decrease in strain at failure and a more brittle response. Tests aimed at examining the influence of wetting on steep slopes show that a 60% decrease in UCS, a 50% drop in cohesion, and 80% decrease in the tensile strength occurs in moderately cemented sand upon introduction to water. In weakly cemented sands, all compressive, cohesive, and tensile strength is lost upon wetting and saturation. The results indicate that particular attention must be given to the relative level of cementation, the effects of groundwater or surficial seepage, and the small-scale strain response when performing geotechnical slope stability analyses on these materials. ?? 2009 ASCE.

  1. Antioxidative properties of phenolic antioxidants isolated from corn steep liquor.

    PubMed

    Niwa, T; Doi, U; Kato, Y; Osawa, T

    2001-01-01

    With the immersion of corn into dilute sulfur oxide during starch-manufacturing processes, corn steep liquor (CSL) remains as leftover material. CSL is often used for fermentation, but its components are not fully understood. To determine the properties of CSL, 12 p-coumaric acid-related compounds were isolated from an ethyl acetate extract of CSL with the guidance of antioxidative activity on the rabbit erythrocyte membrane ghost system. The activity of these compounds was compared against oxidative damages, and it was elucidated that the activity of p-coumaric acid derivatives was mainly affected by their functional groups at the 3-position and less by the conjugated side chain. Moreover, p-coumaric acid derivatives exhibited inhibitory activity stronger than that of tocopherols and ascorbic acid on peroxynitrite-mediated lipoprotein nitration. These findings that p-coumaric acid derivatives, which might play a beneficial role against oxidative damage, exist in CSL suggest this byproduct might be a useful resource of phenolic antioxidants.

  2. Constraining Rates of Biodegradation of Chlorinated Ethenes at Steep Concentration Gradients Using Stable Carbon Isotopes

    NASA Astrophysics Data System (ADS)

    Morrill, P. L.; Seepersad, D. J.; Lacrampe-Couloume, G.; Edwards, E. A.; Sleep, B. E.; McMaster, M. L.; Major, D. W.; Sherwood Lollar, B.

    2005-12-01

    Enhanced biodegradation of emplaced dense non-aqueous phase liquid (DNAPL) sources of tetrachloroethene (PCE) was monitored in a 2-dimensional model aquifer and in a Dover Air Force Base pilot field study. The stable carbon isotope values of PCE and its biodegradation products were monitored along steep concentration gradients near the PCE source zones to quantify first order biodegradation rate constants during a study that assessed the potential for biological enhancement of PCE DNAPL dissolution . Stable carbon isotope measurements are an ideal tool to assess the relative rate of biodegradation versus dissolution since while biodegradation of chlorinated ethenes involves a substantial carbon isotope fractionation, dissolution of chlorinated ethenes is a largely non-fractionating process. Within the dissolved plumes that developed down gradient from the emplaced sources, the isotopic fractionation of PCE and its degradation products in both the model aquifer and field study were consistent with those previously observed in batch laboratory studies. A maximum isotope fractionation of 2.3 permil was observed in the dissolved PCE downgradient, while close to the source zone the carbon isotopic signature of the dissolved PCE remained largely unchanged, due to the continuing dissolution of unfractionated PCE DNAPL. Significant carbon isotopic fractionation was observed adjacent to and/or downstream from the source in the degradation products trichloroethene (TCE), 1,2-dichloroethene (cDCE), and vinyl chloride (VC). Therefore, close to the source zone, confirmation of PCE degradation is based primarily on the appearance of the lesser chlorinated ethene degradation products and isotopic signatures of those products consistent with biodegradation. This trend was observed on a small scale in the model aquifer and similar trends were observed in the field at a larger scale. In both cases biodegradation was correlated with enhanced rates of DNAPL dissolution compared to non

  3. The infrared properties of the GPS and CSS radio sources

    NASA Astrophysics Data System (ADS)

    O'Dea, C. P.

    2016-02-01

    I review the results of three Spitzer studies of GHz-Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) radio galaxies. The luminosity of the IR continuum and the high ionization lines confirm that some GPS/CSS can have central engines which are similar to those of the extended powerful radio sources. This is consistent with the hypothesis that some GPS/CSS can evolve to become the large-scale sources. Warm H_2 is common in the GPS/CSS sources consistent with feedback via jet-ISM interaction. The GPS/CSS seem to have higher star formation rates than typical (2JY + 3CRR) radio sources. This should be confirmed with a larger sample. If compact sources interact with dense, clumpy star forming clouds and if the interaction with the dense medium sufficiently enhances the radio power, these star forming galaxies with enhanced radio emission will be selected for the current bright samples of GPS and CSS sources. This will increase the number of GPS and CSS sources which are observed to be forming stars. If radio sources have longer lives and/or star formation is more common in large radio galaxies, the need for a new population of star forming compact sources with enhanced radio emission is reduced.

  4. Extended-Spectrum beta (β)-Lactamases and Antibiogram in Enterobacteriaceae from Clinical and Drinking Water Sources from Bahir Dar City, Ethiopia

    PubMed Central

    Abera, Bayeh; Kibret, Mulugeta; Mulu, Wondemagegn

    2016-01-01

    Background The spread of Extended-Spectrum beta (β)-Lactamases (ESBL)-producing Enterobacteriaceae has become a serious global problem. ESBL-producing Enterobacteriaceae vary based on differences in antibiotic use, nature of patients and hospital settings. This study was aimed at determining ESBL and antibiogram in Enterobacteriaceae isolates from clinical and drinking water sources in Bahir Dar City, Northwest Ethiopia. Methods Enterobacteriaceae species were isolated from clinical materials and tap water using standard culturing procedures from September 2013 to March 2015. ESBL-producing-Enterobacteriaceae were detected using double-disk method by E-test Cefotaxim/cefotaxim+ clavulanic acid and Ceftazidime/ceftazidime+ clavulanic acid (BioMerieux SA, France) on Mueller Hinton agar (Oxoid, UK). Results Overall, 274 Enterobacteriaceae were isolated. Of these, 210 (44%) were from patients and 64 (17.1%) were from drinking water. The median age of the patients was 28 years. Urinary tract infection and blood stream infection accounted for 60% and 21.9% of Enterobacteriaceae isolates, respectively. Klebsiella pneumoniae was isolated from 9 (75%) of neonatal sepsis. The overall prevalence of ESBL-producing Enterobacteriaceae in clinical and drinking water samples were 57.6% and 9.4%, respectively. The predominant ESBL-producers were K. pneumoniae 34 (69.4%) and Escherichia coli 71 (58.2%). Statistically significant associations were noted between ESBL-producing and non- producing Enterobacteriaceae with regard to age of patients, infected body sites and patient settings (P = 0.001). ESBL-producing Enterobacteriaceae showed higher levels of resistance against chloramphenicol, ciprofloxacin and cotrimoxazole than non-ESBL producers (P = 0.001) Conclusions ESBL-producing Enterobacteriaceae coupled with high levels of other antimicrobials become a major concern for treatment of patients with invasive infections such as blood stream infections, neonatal sepsis and urinary

  5. The role of drinking water sources, consumption of vegetables and seafood in relation to blood arsenic concentrations of Jamaican children with and without Autism Spectrum Disorders.

    PubMed

    Rahbar, Mohammad H; Samms-Vaughan, Maureen; Ardjomand-Hessabi, Manouchehr; Loveland, Katherine A; Dickerson, Aisha S; Chen, Zhongxue; Bressler, Jan; Shakespeare-Pellington, Sydonnie; Grove, Megan L; Bloom, Kari; Wirth, Julie; Pearson, Deborah A; Boerwinkle, Eric

    2012-09-01

    Arsenic is a toxic metal with harmful effects on human health, particularly on cognitive function. Autism Spectrum Disorders (ASDs) are lifelong neurodevelopmental and behavioral disorders manifesting in infancy or early childhood. We used data from 130 children between 2 and 8 years (65 pairs of ASD cases with age- and sex-matched control), to compare the mean total blood arsenic concentrations in children with and without ASDs in Kingston, Jamaica. Based on univariable analysis, we observed a significant difference between ASD cases and controls (4.03 μg/L for cases vs. 4.48 μg/L for controls, P<0.01). In the final multivariable General Linear Model (GLM), after controlling for car ownership, maternal age, parental education levels, source of drinking water, consumption of "yam, sweet potato, or dasheen", "carrot or pumpkin", "callaloo, broccoli, or pak choi", cabbage, avocado, and the frequency of seafood consumption per week, we did not find a significant association between blood arsenic concentrations and ASD status (4.36 μg/L for cases vs. 4.65 μg/L for controls, P=0.23). Likewise, in a separate final multivariable GLM, we found that source of drinking water, eating avocado, and eating "callaloo, broccoli, or pak choi" was significantly associated with higher blood arsenic concentrations (all three P<0.05). Based on our findings, we recommend assessment of arsenic levels in water, fruits, and vegetables, as well as increased awareness among the Jamaican population regarding potential risks for various exposures to arsenic.

  6. Tunable high-power narrow-spectrum external-cavity diode laser at 675 nm as a pump source for UV generation.

    PubMed

    Chi, Mingjun; Jensen, Ole Bjarlin; Erbert, Götz; Sumpf, Bernd; Petersen, Paul Michael

    2011-01-01

    High-power narrow-spectrum diode laser systems based on tapered gain media in an external cavity are demonstrated at 675 nm. Two 2 mm long amplifiers are used, one with a 500 μm long ridge-waveguide section (device A), the other with a 750 μm long ridge-waveguide section (device B). Laser system A based on device A is tunable from 663 to 684 nm with output power higher than 0.55 W in the tuning range; as high as 1.25 W output power is obtained at 675.34 nm. The emission spectral bandwidth is less than 0.05 nm throughout the tuning range, and the beam quality factor M(2) is 2.07 at an output power of 1.0 W. Laser system B based on device B is tunable from 666 to 685 nm. As high as 1.05 W output power is obtained around 675.67 nm. The emission spectral bandwidth is less than 0.07 nm throughout the tuning range, and the beam quality factor M(2) is 1.13 at an output power of 0.93 W. Laser system B is used as a pump source for the generation of 337.6 nm UV light by single-pass frequency doubling in a bismuth triborate (BIBO) crystal. An output power of 109 μW UV light, corresponding to a conversion efficiency of 0.026% W(-1), is attained.

  7. Sediment yields from small, steep coastal watersheds of California

    USGS Publications Warehouse

    Warrick, Jonathan A.; Melack, John M.; Goodridge, Blair M.

    2015-01-01

    Global inventories of sediment discharge to the ocean highlight the importance of small, steep watersheds (i.e., those having drainage areas less than 100,000 km2 and over 1000 m of relief) that collectively provide a dominant flux of sediment. The smallest of these coastal watersheds (e.g., those that have drainage areas less than 1000 km2) can represent a large portion of the drainage areas of active margin coasts, such as California’s coast, but remain almost universally unmonitored. Here we report on the suspended-sediment discharge of several small coastal watersheds (10-56 km2) of the Santa Ynez Mountains, California, that were found to have ephemeral discharge and suspended-sediment concentrations ranging between 1 and over 200,000 mgL-1. Sediment concentrations were weakly correlated with discharge (r2 = 0.10–0.25), and all types of hysteresis patterns were observed during high flows (clockwise, counterclockwise, no hysteresis, and complex). Sediment discharge varied strongly with time and was measurably elevated in one watershed following a wildfire. Although sediment yields varied by over 100-fold across the watersheds (e.g., 15 – 2100 tkm-2 yr -1during the relatively wet 2005 water year), the majority of sediment discharge (65-80%) occurred during only 1% of the time for all watersheds. Furthermore, sampling of dozens of high flow events provides evidence that sediment yields were generally related to peak discharge yields, although these relationships were not consistent across the watersheds. These results suggest that small watersheds of active margins can provide large fluxes of sediment to the coast, but that the rates and timing of this sediment discharge is more irregular in time – and thus more difficult to characterize – than the better monitored and studied watersheds that are 1000-100,000 km2.

  8. Evaluating survey instruments and methods in a steep channel

    NASA Astrophysics Data System (ADS)

    Scott, Daniel N.; Brogan, Daniel J.; Lininger, Katherine B.; Schook, Derek M.; Daugherty, Ellen E.; Sparacino, Matthew S.; Patton, Annette I.

    2016-11-01

    Methods for surveying and analyzing channel bed topography commonly lack a rigorous characterization of their appropriateness for project objectives. We compare four survey methods: a hand level, two different methods of surveying with a laser rangefinder, and a real-time kinematic GNSS (RTK-GNSS) to explore their accuracy in determining channel bed slope and roughness for a study reach in a small, dry, steep channel. Additionally, we evaluate the variability among four operators for each survey technique. Two methods of calculating reach slope were computed: a regression on the channel profile and a calculation using only survey endpoints. Using data from the RTK-GNSS as our accuracy reference, the hand level and two-person laser rangefinder surveying systems performed with high accuracy (< 5% error in estimating slope, < 10% error in estimating roughness), while the one-person laser rangefinder survey system performed with considerably lower accuracy (up to 54% error in roughness and slope). Variability between operators was found to be very low (coefficients of variation ranged from 0.001 to 0.046) for all survey systems except the one-person laser rangefinder system, suggesting that survey data collected by different operators can be validly compared. Due to reach-scale concavity, calculating slope using a regression produced significantly different values than those obtained by using only survey endpoints, suggesting that caution must be taken in choosing the most appropriate method of calculating slope for a given project objective. We present recommendations for choosing appropriate survey and analysis methods to accomplish various surveying objectives.

  9. Utilization of corn steep liquor for biosynthesis of pullulan, an important exopolysaccharide.

    PubMed

    Sharma, Nishat; Prasad, G S; Choudhury, Anirban Roy

    2013-03-01

    Five different agricultural wastes viz. rice bran oil cake, soya bean oil cake, cotton seed oil cake, mustard seed oil cake and corn steep liquor (CSL) were evaluated for their use as nutrient along with 15% (w/v) glucose as carbon source for biosynthesis of pullulan using Aureobasidium pullulans RBF 4A3. Among the selected agricultural wastes, CSL was found to be the best and supported production of 77.92gL(-1) pullulan under un-optimized conditions. Single point optimization technique resulted in increase in 18% pullulan (88.59gL(-1)) production. The process was successfully validated in a 7-L fermenter and a process economic analysis has suggested that use of CSL as nutrient may result in 3-fold reduction of cost of raw materials for pullulan production as compared to a process where conventional nitrogen sources were used. These observations may be helpful in development of a cost effective process for pullulan production.

  10. Along-Arc and Back-Arc Attenuation, Site Response, and Source Spectrum for the Intermediate-Depth 8 January 2006 M 6.7 Kythera, Greece, Earthquake

    USGS Publications Warehouse

    Boore, D.M.; Skarlatoudis, A.A.; Margaris, B.N.; Costas, B.P.; Ventouzi, C.

    2009-01-01

    An M 6.7 intermediate-depth (66 km), in-slab earthquake occurring near the island of Kythera in Greece on 8 January 2006 was well recorded on networks of stations equipped with acceleration sensors and with broadband velocity sensors. All data were recorded digitally using recording instruments with resolutions ranging from almost 11 to 24 bits. We use data from these networks to study the distance dependence of the horizontal-component Fourier acceleration spectra (FAS) and horizontal-component pseudoabsolute response spectral acceleration (PSA). For purposes of simulating motions in the future, we parameterize the distance decay using several forms of the geometrical-spreading function, for each of which we derive Q as a function of frequency. By extrapolating the distance decay back to 1 km, we obtain a reference spectrum that can be used in future simulations. This spectrum requires a more complicated spectral shape than the classic single-corner-frequency model; in particular, there appears to be an enhancement of motion around 0.2-0.3 Hz that may be due to the radiation of a 3-5 sec pulse from the source. We infer a ??0 value of about 0.055 sec for rock stations and a stress parameter in the range of 400-600 bars. We also find distinctive differences in the site response of stations on soft soil and soil; both the FAS and the 5% damped PSA amplifications have similar peak amplitudes (about 2 and 4 for soil and soft-soil sites, respectively, relative to the rock sites) at similar frequencies (between about 0.4 and 2.0 Hz, with the soft-soil amplifications peaking at somewhat lower frequencies than the soil amplifications). One of the most distinctive features of the data is the clear difference in the motions for along-arc and back-arc stations, with the former being significantly higher than the latter over a broad range of frequencies at distances beyond about 250 km. The motions from the Kythera earthquake are roughly comparable to those from intermediate

  11. Zellweger Spectrum

    MedlinePlus

    ... Resources Conference News Contact Us Donate The Zellweger Spectrum Zellweger Syndrome, Neonatal Adrenoleukodystrophy (NALD), and Infantile Refsum’s ... of severity of disease. What causes the Zellweger spectrum of diseases? As we mentioned, disorders of the ...

  12. The compact radio structure of radio-loud NLS1 galaxies and the relationship to CSS sources

    NASA Astrophysics Data System (ADS)

    Gu, M.; Chen, Y.; Komossa, S.; Yuan, W.; Shen, Z.

    2016-02-01

    Narrow-line Seyfert 1 galaxies are thought to be young AGNs with relatively small black hole masses and high accretion rates. Radio-loud narrow-line Seyfert 1 galaxies (RLNLS1s) are very special, because some of them show blazar-like characteristics, while others resemble compact steep-spectrum sources. Relativistic jets were shown to exist in a few RLNLS1s based on VLBI observations and confirmed by the gamma-ray flaring of some of them. These properties may possibly be contrary to typical radio-loud AGNs, in light of the low black-hole masses, and high accretion rates. We present the compact radio structure of fourteen RLNLS1 galaxies from Very Long Baseline Array observations at 5 GHz in 2013. Although all these sources are very radio-loud with {R > 100}, their jet properties are diverse, in terms of their milli-arcsecond (mas) scale (pc scale) morphology and their overall radio spectral shape. The core brightness temperatures of our sources are significantly lower than those of blazars, therefore, the beaming effect is generally not significant in our sources, compared to blazars. This implies that the bulk jet speed may likely be low in our sources. The relationship between RLNLS1s and compact steep-spectrum sources, and the implications on jet formation are discussed based on the pc-scale jet properties.

  13. Flood and Debris Flow Hazard Predictions in Steep, Burned Landscapes

    NASA Astrophysics Data System (ADS)

    Rengers, Francis; McGuire, Luke; Kean, Jason; Staley, Dennis

    2016-04-01

    scale. The calibrated effective watershed hydraulic conductivity was low for both models, even for storms occurring several months after the fire, consistent with wildfire-induced water-repellency being retained throughout that time. Both models captured the timing of flow peaks, although neither model correctly simulated the flow depth. This study suggests that a kinematic wave model, which is simpler and more computationally efficient, is a justifiable approach for predicting flood and debris flow timing in steep, burned watersheds. By demonstrating the applicability of these models, this study takes an important step towards the development of process-based methods to assess post-wildfire flood and debris flow hazards.

  14. Effect of Wildfire on Sediment Sorting in a Steep Channel

    NASA Astrophysics Data System (ADS)

    Florsheim, J. L.; Chin, A.; O'Hirok, L.; Storesund, R.

    2014-12-01

    Wildfire is an external forcing factor in the landscape. In chaparral environments, wildfire initiates transport of well-sorted fine sediment through dry-ravel processes on hillslopes and facilitates delivery of sediment to stream channels. In turn, this periodic post-fire sediment influx governs sorting of channel-bed material during subsequent floods that mobilize and transport the sediment downstream. We investigated the effects of the May 2013 Springs Wildfire in the Santa Monica Mountains in semi-arid southern California with field measurements and terrestrial LiDAR scanning. Before the fire, sediment sorting within the heterogeneous bed material present in Big Sycamore Creek was controlled by organized step-pool bedforms. Boulders formed steps with relatively finer cobbles, gravel, and sand filling the pools. Before the fire, the grain size distribution present in the substrate between boulder steps was relatively coarse (D84 = 250 mm), in contrast to that in the influx of sediment contributed by post-fire dry-ravel processes deposited at channel margins (D84 = 8 mm). Flow shear stress during one small flood in 2014 (post-fire) was adequate to mobilize fine dry ravel- related sediment. Transport capacity was sufficient to mobilize and transport this sediment within a study reach; however, it was not adequate to flush the fine material downstream. Shear stress required to mobilize sediment contributed by dry ravel was substantially less than that required to transport the substrate material present before the wildfire. The small flood deposited fine sediment (D84 = 16 mm) as flow lost capacity. Resulting deposition buried bedforms, changing the step-pool profile to a plane bed. The relatively poorly sorted, coarse, rough bed changed to a well sorted, fine, smooth, bed. These changes have implications for sediment transport dynamics and aquatic ecology. In steep, semi-arid, chaparral fluvial systems, sediment derived from dry-ravel processes influences the

  15. Spectrum and Morphology of the Two Brightest Milagro Sources in the Cygnus Region: MGRO J2019+37 and MGRO J2031+41

    NASA Technical Reports Server (NTRS)

    Abdo, A. A.; Abeysekara, U.; Allen, B, T.; Aune, T.; Berley, D.; Bonamente, E.; Christopher, G. E.; DeYoung, T.; Dingus, B. L.; Ellsworth, R. W.; Galbraith-Frew, J. G.; Gonzalez, M. M.; Goodman, J. A.; Hoffman, C. M.; Huentemeyer, P. H.; Hui, C. M.; Kolterman, B. E.; Linnemann, J . T.; McEnery, J. E.; Mincer, A. I.; Morgan, T.; Nemethy, P.; Pretz, J.; Ryan, J. M.; Vasileiou, V.

    2012-01-01

    The Cygnus region is a very bright and complex portion of the TeV sky, host to unidentified sources and a diffuse excess with respect to conventional cosmic-ray propagation models. Two of the brightest TeV sources, MGRO J2019+37 and MGRO J2031+41, are analyzed using Milagro data with a new technique, and their emission is tested under two different spectral assumptions: a power law and a power law with an exponential cutoff. The new analysis technique is based on an energy estimator that uses the fraction of photomultiplier tubes in the observatory that detect the extensive air shower. The photon spectrum is measured in the range 1-100 TeV using the last three years of Milagro data (2005-2008), with the detector in its final configuration. An F-test indicates that MGRO J2019+37 is better fit by a power law with an exponential cutoff than by a simple power law. The best-fitting parameters for the power law with exponential cutoff model are a normalization at 10 TeV of 7(sup +5 sub -2) × 10(exp -10)/ s /sq m/ TeV, a spectral index of 2.0(sup +0.5 sub -10), and a cutoff energy of 29(sup +50 sub -16) TeV. MGRO J2031+41 shows no evidence of a cutoff. The best-fitting parameters for a power law are a normalization of 2.1(sup +0.6 sub -0.6) × 10(exp -10)/ s/sq m/ TeV and a spectral index of 3.22(sup +0.23 sub -0.18. The overall flux is subject to a approx.. 30% systematic uncertainty. The systematic uncertainty on the power-law indices is approx. 0.1. Both uncertainties have been verified with cosmic-ray data. A comparison with previous results from TeV J2032+4130, MGRO J2031+41, and MGRO J2019+37 is also presented.

  16. Spectrum and Morphology of the Two Brightest Milagro Sources in the Cygnus Region: MGRO J2019+37 and MGRO J2031+41

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Abeysekara, U.; Allen, B. T.; Aune, T.; Berley, D.; Bonamente, E.; Christopher, G. E.; DeYoung, T.; Dingus, B. L.; Ellsworth, R. W.; Galbraith-Frew, J. G.; Gonzalez, M. M.; Goodman, J. A.; Hoffman, C. M.; Hüntemeyer, P. H.; Hui, C. M.; Kolterman, B. E.; Linnemann, J. T.; McEnery, J. E.; Mincer, A. I.; Morgan, T.; Nemethy, P.; Pretz, J.; Ryan, J. M.; Saz Parkinson, P. M.; Shoup, A.; Sinnis, G.; Smith, A. J.; Vasileiou, V.; Walker, G. P.; Williams, D. A.; Yodh, G. B.

    2012-07-01

    The Cygnus region is a very bright and complex portion of the TeV sky, host to unidentified sources and a diffuse excess with respect to conventional cosmic-ray propagation models. Two of the brightest TeV sources, MGRO J2019+37 and MGRO J2031+41, are analyzed using Milagro data with a new technique, and their emission is tested under two different spectral assumptions: a power law and a power law with an exponential cutoff. The new analysis technique is based on an energy estimator that uses the fraction of photomultiplier tubes in the observatory that detect the extensive air shower. The photon spectrum is measured in the range 1-100 TeV using the last three years of Milagro data (2005-2008), with the detector in its final configuration. An F-test indicates that MGRO J2019+37 is better fit by a power law with an exponential cutoff than by a simple power law. The best-fitting parameters for the power law with exponential cutoff model are a normalization at 10 TeV of 7+5 -2 × 10-10 s-1 m-2 TeV-1, a spectral index of 2.0+0.5 -1.0, and a cutoff energy of 29+50 -16 TeV. MGRO J2031+41 shows no evidence of a cutoff. The best-fitting parameters for a power law are a normalization of 2.1+0.6 -0.6 × 10-10 s-1 m-2 TeV-1 and a spectral index of 3.22+0.23 -0.18. The overall flux is subject to a ~30% systematic uncertainty. The systematic uncertainty on the power-law indices is ~0.1. Both uncertainties have been verified with cosmic-ray data. A comparison with previous results from TeV J2032+4130, MGRO J2031+41, and MGRO J2019+37 is also presented.

  17. Critical Shields Values in Coarse-Bedded Steep Streams

    NASA Astrophysics Data System (ADS)

    Bunte, K.; Abt, S. R.; Swingle, K. W.; Cenderelli, D. A.; Schneider, J. M.

    2013-12-01

    Critical Shields values for poorly mobile, semi-alluvial mountain streams are not provided by the original Shields diagram and are still debated. This empirical study uses gravel bedload samples collected with unbiasing samplers at 22 stream sites and establishes a relation between instantaneous discharge and the largest sampled bedload particle size for each site. Using relations between flow depth and discharge, critical Shields values for particle sizes corresponding to the bed surface D50, D16, D84, and D50s sizes at each site can be backcomputed from the established critical flow or flow competence relations. Critical Shields values for all bed material particle size percentiles increase with stream gradient Sx and are stratifiable by relative flow depth d/D50 and relative roughness (D84/d) which improves prediction. Critical Shields values for the bed D16 sizes (τ*c16) are approximately three times larger than those for the D50 size (τ*c50), while those for the D84 size (τ*c84) are approximately half of τ*c50. It remains unclear to what extent physical processes or numerical artifacts contribute to determining critical Shields values. Specific critical Shields values are needed to predict the average largest particle size mobile at bankfull flow (DBmax,bf). So far, no Shields values are available for this common task, especially not in poorly mobile semi-alluvial streams. Critical bankfull Shields values (τ*cbf) backcomputed from the largest particles transported at bankfull flow approach τ*c16 at steep gradient streams and τ*c84 at low gradients and therefore increase very steeply with Sx. The relation τ*cbf = f(Sx) is stratified by bed mobility D50/DBmax,bf and predictable if bed mobility can be categorized in the field. Non-critical Shields values (τ*bf50) computed from bankfull flow depth and the bed surface D50 size differ from τ*c50 and from critical bankfull Shields values τ*cbf. Only in bankfull mobile streams where D50/DBmax,bf = 1 can

  18. A steep-slope transistor based on abrupt electronic phase transition.

    PubMed

    Shukla, Nikhil; Thathachary, Arun V; Agrawal, Ashish; Paik, Hanjong; Aziz, Ahmedullah; Schlom, Darrell G; Gupta, Sumeet Kumar; Engel-Herbert, Roman; Datta, Suman

    2015-08-07

    Collective interactions in functional materials can enable novel macroscopic properties like insulator-to-metal transitions. While implementing such materials into field-effect-transistor technology can potentially augment current state-of-the-art devices by providing unique routes to overcome their conventional limits, attempts to harness the insulator-to-metal transition for high-performance transistors have experienced little success. Here, we demonstrate a pathway for harnessing the abrupt resistivity transformation across the insulator-to-metal transition in vanadium dioxide (VO2), to design a hybrid-phase-transition field-effect transistor that exhibits gate controlled steep ('sub-kT/q') and reversible switching at room temperature. The transistor design, wherein VO2 is implemented in series with the field-effect transistor's source rather than into the channel, exploits negative differential resistance induced across the VO2 to create an internal amplifier that facilitates enhanced performance over a conventional field-effect transistor. Our approach enables low-voltage complementary n-type and p-type transistor operation as demonstrated here, and is applicable to other insulator-to-metal transition materials, offering tantalizing possibilities for energy-efficient logic and memory applications.

  19. Polarization dependence of light scattered from rough surfaces with steep slopes

    NASA Astrophysics Data System (ADS)

    O'Donnell, Kevin A.; Knotts, Michael E.

    1991-11-01

    We discuss measurements of the infrared scattering properties of one- and two-dimensional conducting randomly rough surfaces. The surfaces are fabricated in photoresist and are checked with a stylus profilometer to verify that the surface statistics agree with the desired results. For surfaces that have steep slopes and lateral scale sizes comparable to the illumination wavelength, we observe strongly enhanced backscattering toward the source. These observations are shown to be strongly dependent on polarization. In the case of a one- dimensional surface, four distinct quantities appear in the Stokes scattering matrix, and examples of measurements of these quantities are presented. For the case of a two- dimensionally rough surface it is discussed that, even if the incident field is purely linearly polarized, the scattered light consists of both polarized and randomly polarized components. In the backscattering region, the polarized component contains linear, elliptical, and even nearly circular polarization states at various field angles. These data are interpreted and are consistent with the statistical isotropy of the surface.

  20. Cost-effective temporary microirrigation system for grass establishment on environmentally sensitive steep slopes

    SciTech Connect

    Gyasi-Agyei, Y.

    2004-05-15

    An advanced technology cost-effective drip irrigation system design and setup on environmentally sensitive elevated steep slopes (batters) of a coal train derailment site in Central Queensland, Australia, are presented. The final profile of the coal burial site consists of six batters and associated berms with a drop in elevation of about 35 m. A small dam constructed downstream of the confluence of the two main drainage channels at the site supplied water for irrigation of the batters to aid the establishment of grass to control erosion. Water was periodically pumped from the small dam to three storage tanks using a petrol (gas) pump. Three solar pumps drew water from the storage tanks and dam to irrigate the top four batters. Contactors, pressure switches and irrigation control valves in turn shared a single solar power source between the solar pumps. Level balls (floating switches) placed in the storage tanks cut the solar power supply to the pumps when the storage tanks were nearly empty. On the whole, the irrigation system worked very well and excellent grass cover was established within 12 weeks. Given the environmental risks associated with the on-site burying of coal, and the estimated cost of about AU$11.73/m{sup 2} (every 10 years) in maintenance if the railway batters are not treated, the estimated total cost of AU$4.61/m{sup 2} of batter area treated with irrigation, including AU$3.08/m{sup 2} in irrigation cost, is justified.

  1. Negative Capacitance in Organic/Ferroelectric Capacitor to Implement Steep Switching MOS Devices.

    PubMed

    Jo, Jaesung; Choi, Woo Young; Park, Jung-Dong; Shim, Jae Won; Yu, Hyun-Yong; Shin, Changhwan

    2015-07-08

    Because of the "Boltzmann tyranny" (i.e., the nonscalability of thermal voltage), a certain minimum gate voltage in metal-oxide-semiconductor (MOS) devices is required for a 10-fold increase in drain-to-source current. The subthreshold slope (SS) in MOS devices is, at best, 60 mV/decade at 300 K. Negative capacitance in organic/ferroelectric materials is proposed in order to address this physical limitation in MOS technology. Here, we experimentally demonstrate the steep switching behavior of a MOS device-that is, SS ∼ 18 mV/decade (much less than 60 mV/decade) at 300 K-by taking advantage of negative capacitance in a MOS gate stack. This negative capacitance, originating from the dynamics of the stored energy in a phase transition of a ferroelectric material, can achieve the step-up conversion of internal voltage (i.e., internal voltage amplification in a MOS device). With the aid of a series-connected negative capacitor as an assistive device, the surface potential in the MOS device becomes higher than the applied gate voltage, so that a SS of 18 mV/decade at 300 K is reliably observed.

  2. Waste Soybean Oil and Corn Steep Liquor as Economic Substrates for Bioemulsifier and Biodiesel Production by Candida lipolytica UCP 0998

    PubMed Central

    Souza, Adriana Ferreira; Rodriguez, Dayana M.; Ribeaux, Daylin R.; Luna, Marcos A. C.; Lima e Silva, Thayse A.; Andrade, Rosileide F. Silva; Gusmão, Norma B.; Campos-Takaki, Galba M.

    2016-01-01

    Almost all oleaginous microorganisms are available for biodiesel production, and for the mechanism of oil accumulation, which is what makes a microbial approach economically competitive. This study investigated the potential that the yeast Candida lipolytica UCP0988, in an anamorphous state, has to produce simultaneously a bioemulsifier and to accumulate lipids using inexpensive and alternative substrates. Cultivation was carried out using waste soybean oil and corn steep liquor in accordance with 22 experimental designs with 1% inoculums (107 cells/mL). The bioemulsifier was produced in the cell-free metabolic liquid in the late exponential phase (96 h), at Assay 4 (corn steep liquor 5% and waste soybean oil 8%), with 6.704 UEA, IE24 of 96.66%, and showed an anionic profile. The emulsion formed consisted of compact small and stable droplets (size 0.2–5 µm), stable at all temperatures, at pH 2 and 4, and 2% salinity, and showed an ability to remove 93.74% of diesel oil from sand. The displacement oil (ODA) showed 45.34 cm2 of dispersion (central point of the factorial design). The biomass obtained from Assay 4 was able to accumulate lipids of 0.425 g/g biomass (corresponding to 42.5%), which consisted of Palmitic acid (28.4%), Stearic acid (7.7%), Oleic acid (42.8%), Linoleic acid (19.0%), and γ-Linolenic acid (2.1%). The results showed the ability of C. lipopytica to produce both bioemulsifier and biodiesel using the metabolic conversion of waste soybean oil and corn steep liquor, which are economic renewable sources. PMID:27669227

  3. Numerical verification of the steepness of three and four degrees of freedom Hamiltonian systems

    NASA Astrophysics Data System (ADS)

    Schirinzi, Gabriella; Guzzo, Massimiliano

    2015-01-01

    We describe a new algorithm for the numerical verification of steepness, a necessary property for the application of Nekhoroshev's theorem, of functions of three and four variables. Specifically, by analyzing the Taylor expansion of order four, the algorithm analyzes the steepness of functions whose Taylor expansion of order three is not steep. In this way, we provide numerical evidence of steepness of the Birkhoff normal form around the Lagrangian equilibrium points L4-L5 of the spatial restricted three-body problem (for the only value of the reduced mass for which the Nekhoroshev stability was still unknown), and of the four-degrees-of-freedom Hamiltonian system obtained from the Fermi-Pasta-Ulam problem by setting the number of particles equal to four.

  4. Laboratory Studies of Steep and Breaking Deep Water Waves in a Convergent Channel

    DTIC Science & Technology

    2015-05-28

    TASK NO RR023- 11 TITLE (Include Security Classification) Laboratory Studies of Steep and Breaking Deep Water Waves in a Convergent Channel...These include the relative motion between the water and, say, a ship in the seaway or a cylindrical obstacle in a wavefield; wind blowing over the water ...in deep water . The present experiments were conducted to study the evolution of steep and breaking deep water waves. The waves were made to steepen

  5. The electrical breakdown characteristics of oil-paper insulation under steep front impulse voltages

    SciTech Connect

    Vandermaar, A.J.; Wang, M.; Neilson, J.B. ); Srivastava, K.D. )

    1994-10-01

    Disconnecting switch operations in gas insulated equipment cause transient voltages with rise times as steep as 5 to 20 nanoseconds and magnitudes as high as 2.5 pu. There is very little information on the effect of these transients on oil-paper insulated equipment. There have been reports, however of transformer and bushing failures caused by these transients. The electrical breakdown characteristics of oil-paper insulation under steep front impulse were studied in this project, which was co-sponsored by the Canadian Electrical Association and B.C. Hydro. V[sub 50] (50% breakdown probability voltage) breakdown data was obtained with steep front (10 ns/2500 [mu]s), lightning and switching impulse waveforms. Insulation breakdown voltage vs breakdown time (V-t) data and multiple impulse breakdown data were obtained with the steep front impulse waveform. The V[sub 50] results showed that the breakdown strengths were lower for steep front impulses than for lightning impulses. The multiple impulse breakdown results showed that oil-paper insulation breakdown strength can be lower than 100 kV/mm. These results are alarming, since they suggest that oil-paper insulated equipment subjected to steep front transients will fail at voltages below the lightning impulse design level (BIL). The Volt-time data had a discontinuity. The breakdown process at risetime below about 50 ns was different from the breakdown process at rise times above 50 ns.

  6. A Peculiar Class of Debris Disks from Herschel/DUNES: A Steep Fall Off in the Far Infrared

    NASA Technical Reports Server (NTRS)

    Ertel, S.; Wolf, S.; Marshall, J. P.; Eiroa, C.; Augereau, J. C.; Krivov, A. V.; Lohne, T.; Absil, O.; Ardila, D.; Arevalo, M.; Bayo, A.; Bryden, G.; del Burgo, C.; Greaves, J.; Kennedy, G.; Lebreton, J.; Liseau, R.; Maldonado, J.; Montesinos, B.; Mora, A.; Pilbratt, G. L.; Sanz-Forcada, J.; Stapelfeldt, K.; White, G. J.

    2012-01-01

    Context. The existence of debris disks around old main sequence stars is usually explained by continuous replenishment of small dust grains through collisions from a reservoir of larger objects. Aims. We present photometric data of debris disks around HIP 103389 (HD199260), HIP 100350 (HN Peg, HD206860), and HIP 114948 (HD 219482), obtained in the context of our Herschel Open TIme Key Program DUNES (DUst around NEarby Stars). Methods. We used Herschel/PACS to detect the thermal emission of the three debris disks with a 30 sigma sensitivity of a few mJy at l00 micron and 160 micron. In addition, we obtained Herschel/PACS photometric data at 70 micron for HIP 103389. These observations are complemented by a large variety of optical to far-infrared photometric data. Two different approaches are applied to reduce the Herschel data to investigate the impact of data reduction on the photometry. We fit analytical models to the available spectral energy distribution (SED) data using the fitting method of simulated therma1 annealing as well as a classical grid search method. Results. The SEDs of the three disks potentially exhibit an unusually steep decrease at wavelengths >= 70 micron. We investigate the significance of the peculiar shape of these SEDs and the impact on models of the disks provided it is real. Using grain compositions that have been applied successfully for modeling of many other debris disks, our modeling reveals that such a steep decrease of the SEDs in the long wavelength regime is inconsistent with a power-law exponent of the grain size distribution -3.5 expected from a standard equilibrium collisional cascade. In contrast, a steep grain size distribution or, alternatively an upper grain size in the range of few tens of micrometers are implied. This suggests that a very distinct range of grain sizes would dominate the thermal. emission of such disks. However, we demonstrate that the understanding of the data of faint sources obtained with Herschel is

  7. A peculiar class of debris disks from Herschel/DUNES. A steep fall off in the far infrared

    NASA Astrophysics Data System (ADS)

    Ertel, S.; Wolf, S.; Marshall, J. P.; Eiroa, C.; Augereau, J.-C.; Krivov, A. V.; Löhne, T.; Absil, O.; Ardila, D.; Arévalo, M.; Bayo, A.; Bryden, G.; del Burgo, C.; Greaves, J.; Kennedy, G.; Lebreton, J.; Liseau, R.; Maldonado, J.; Montesinos, B.; Mora, A.; Pilbratt, G. L.; Sanz-Forcada, J.; Stapelfeldt, K.; White, G. J.

    2012-05-01

    Context. The existence of debris disks around old main sequence stars is usually explained by continuous replenishment of small dust grains through collisions from a reservoir of larger objects. Aims: We present photometric data of debris disks around HIP 103389 (HD 199260), HIP 107350 (HN Peg, HD 206860), and HIP 114948 (HD 219482), obtained in the context of our Herschel open time key program DUNES (DUst around NEarby Stars). Methods: We used Herschel/PACS to detect the thermal emission of the three debris disks with a 3σ sensitivity of a few mJy at 100 μm and 160 μm. In addition, we obtained Herschel/PACS photometric data at 70 μm for HIP 103389. These observations are complemented by a large variety of optical to far-infrared photometric data. Two different approaches are applied to reduce the Herschel data to investigate the impact of data reduction on the photometry. We fit analytical models to the available spectral energy distribution (SED) data using the fitting method of simulated thermal annealing as well as a classical grid search method. Results: The SEDs of the three disks potentially exhibit an unusually steep decrease at wavelengths ≥70 μm. We investigate the significance of the peculiar shape of these SEDs and the impact on models of the disks provided it is real. Using grain compositions that have been applied successfully for modeling of many other debris disks, our modeling reveals that such a steep decrease of the SEDs in the long wavelength regime is inconsistent with a power-law exponent of the grain size distribution -3.5 expected from a standard equilibrium collisional cascade. In contrast, a steep grain size distribution or, alternatively an upper grain size in the range of few tens of micrometers are implied. This suggests that a very distinct range of grain sizes would dominate the thermal emission of such disks. However, we demonstrate that the understanding of the data of faint sources obtained with Herschel is still incomplete

  8. The Lockman Hole project: LOFAR observations and spectral index properties of low-frequency radio sources

    NASA Astrophysics Data System (ADS)

    Mahony, E. K.; Morganti, R.; Prandoni, I.; van Bemmel, I. M.; Shimwell, T. W.; Brienza, M.; Best, P. N.; Brüggen, M.; Calistro Rivera, G.; de Gasperin, F.; Hardcastle, M. J.; Harwood, J. J.; Heald, G.; Jarvis, M. J.; Mandal, S.; Miley, G. K.; Retana-Montenegro, E.; Röttgering, H. J. A.; Sabater, J.; Tasse, C.; van Velzen, S.; van Weeren, R. J.; Williams, W. L.; White, G. J.

    2016-12-01

    The Lockman Hole is a well-studied extragalactic field with extensive multi-band ancillary data covering a wide range in frequency, essential for characterizing the physical and evolutionary properties of the various source populations detected in deep radio fields (mainly star-forming galaxies and AGNs). In this paper, we present new 150-MHz observations carried out with the LOw-Frequency ARray (LOFAR), allowing us to explore a new spectral window for the faint radio source population. This 150-MHz image covers an area of 34.7 square degrees with a resolution of 18.6 × 14.7 arcsec and reaches an rms of 160 μJy beam-1 at the centre of the field. As expected for a low-frequency selected sample, the vast majority of sources exhibit steep spectra, with a median spectral index of α _{150}^{1400}=-0.78± 0.015. The median spectral index becomes slightly flatter (increasing from α _{150}^{1400}=-0.84 to α _{150}^{1400}=-0.75) with decreasing flux density down to S150 ˜10 mJy before flattening out and remaining constant below this flux level. For a bright subset of the 150-MHz selected sample, we can trace the spectral properties down to lower frequencies using 60-MHz LOFAR observations, finding tentative evidence for sources to become flatter in spectrum between 60 and 150 MHz. Using the deep, multi-frequency data available in the Lockman Hole, we identify a sample of 100 ultra-steep-spectrum sources and 13 peaked-spectrum sources. We estimate that up to 21 per cent of these could have z > 4 and are candidate high-z radio galaxies, but further follow-up observations are required to confirm the physical nature of these objects.

  9. Spectrum Recombination.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1984-01-01

    Describes several methods of executing lecture demonstrations involving the recombination of the spectrum. Groups the techniques into two general classes: bringing selected portions of the spectrum together using lenses or mirrors and blurring the colors by rapid movement or foreshortening. (JM)

  10. Development and Validation of a Low Cost, Flexible, Open Source Robot for Use as a Teaching and Research Tool across the Educational Spectrum

    ERIC Educational Resources Information Center

    Howell, Abraham L.

    2012-01-01

    In the high tech factories of today robots can be used to perform various tasks that span a wide spectrum that encompasses the act of performing high-speed, automated assembly of cell phones, laptops and other electronic devices to the compounding, filling, packaging and distribution of life-saving pharmaceuticals. As robot usage continues to…

  11. A LOFAR view on the duty cycle of young radio sources

    NASA Astrophysics Data System (ADS)

    Brienza, M.; Morganti, R.; Shulevski, A.; Godfrey, L.; Vilchez, N.

    2016-02-01

    Compact Steep Spectrum, Gigahertz Peaked Spectrum, and High Frequency Peak (CSS, GPS, HFP) sources are considered to be young radio sources, but the details of their duty cycle are not well understood. In some cases they are thought to develop in FRI/FRII radio galaxies while in other cases their jets may remain confined within the host galaxy, and some may experience intermittent activity or die prematurely, never reaching the size of large classical double radio galaxies. Studying in a systematic way the presence and the properties of any extended emission surrounding these compact sources can provide firmer constraints on their evolutionary history and on the timescales of activity of the radio source. Remnant emission from previous outbursts is supposed to have very low surface brightness and to be brighter at low frequency. Taking advantage of the unprecedented sensitivity and resolution provided by the Low Frequency Array (LOFAR) we have started a systematic search of new CSS, GPS, and HFP sources with extended emission, as well as a more detailed study of some well-known of these sources. Here we present the key points of our search in the LOFAR fields and a more in-depth analysis on the source B2 0258+35, a CSS source surrounded by a pair of large, diffuse radio lobes. In this way, we aim to provide a better census of restarted sources and a better knowledge of the variety of their duty cycle.

  12. Technical note: Common characteristics of directional spreading-steepness joint distribution in freak wave events

    NASA Astrophysics Data System (ADS)

    Liu, Shouhua; Li, Yizhen; Yue, Xinyang

    2016-06-01

    Seven freak wave incidents previously documented in the real ocean in combination with model hindcast simulations are used to study the variations associated with freak-wave-related parameters, such as wave steepness, directional spreading, and frequency bandwidth. Unlike the strong correlations between the freak wave parameters and freak waves' occurrence which were obtained in experimental and physical research, the correlations are not clear in the freak waves occurring in the real ocean. Wave directional spreading-steepness joint distribution is introduced and common visual features were found in the joint distribution when freak waves occur among seven "freakish" sea states. The visual features show that freak wave incidents occur when the steepness is large and directional spreading is small. Besides large steepness and small directional spreading, a long-duration, relatively rough sea state is also necessary for the freak wave generation. The joint distribution is more informative than any single statistical wave parameter. The continuous sea states of local large steepness and small directional spreading are supposed to generate freak waves, and two-dimensional distribution visualization is found to be a useful tool for freak waves' forecast. The common visual features of joint distributions supply an important cue for the theoretical and experimental research.

  13. Flow, Sediment Transport, and Erosion in Steep Mountain Channels: an Alpine Symphony

    NASA Astrophysics Data System (ADS)

    Kirchner, J. W.; Beer, A. R.; Heimann, F.; Rickenmann, D.; Schneider, J. M.; von Boetticher, A.; Turowski, J. M.

    2015-12-01

    Steep headwater channels comprise a large fraction of the total channel length in mountainous regions. They control the transport of water, solutes, and sediments to larger rivers downstream, and regulate the erosional development of many mountain landscapes. Flow and transport processes in these steep channels contrast with those in their lower-gradient counterparts. Steep streams have complex bed morphology, with large roughness relative to the flow depth, and the flow is likewise complex, often comprising a variable mixture of air and water. Here we present several examples from Switzerland highlighting recent research into hydraulics, sediment transport, and bedrock erosion in steep Alpine channels. The Riedbach presents a striking natural experiment, in which the channel gradient steepens from roughly 3% to more than 40% in less than 1km, while the discharge, flow width, and sediment transport rates remain roughly constant. Measurements at the Riedbach illustrate the self-adjustment of flow velocity and bed roughness in steep mountain channels. Data from the Erlenbach, an intensively instrumented stream in the Alpine foothills, illustrate how the bed configuration of such streams regulates the relationship between flow and sediment transport. Field studies at the Gornera illustrate how flow patterns control the spatial distribution of bedrock erosion in this glacier-fed stream in the shadow of the Matterhorn. We present an overview of these studies and discuss their implications.

  14. Crustal Structure and Deformation of the Yakutat Microplate: New Insights From STEEP Marine Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Lowe, L. A.; Gulick, S. P.; Christeson, G.; van Avendonk, H.; Reece, R.; Elmore, R.; Pavlis, T.

    2008-12-01

    In fall 2008, we will conduct an active source marine seismic experiment of the offshore Yakutat microplate in the northern Gulf of Alaska. The survey will be conducted aboard the academic research vessel, R/V Marcus Langseth, collecting deep-penetrating multi-channel seismic reflection survey using an 8-km, 640 channel hydrophone streamer and a 6600 cu. in., 36 airgun array. The survey is the concluding data acquisition phase for the ST. Elias Erosion and tectonics Project (STEEP), a multi-institution NSF-Continental Dynamics project investigating the interplay of climate and tectonics in the Chugach-St. Elias Mountains in southern Alaska. The experiment will also provide important site survey information for possible future Integrated Ocean Drilling Program investigations. Two profiles coincident with wide-angle refraction data (see Christeson, et al., this session) will image structural changes across the Dangerous River Zone from east to west and the Transition Fault from south to north. We will also image the western portion of the Transition Fault to determine the nature of faulting along this boundary including whether or not the Pacific Plate is underthrusting beneath the Yakutat microplate as part of this collision. Our westernmost profile will image the Kayak Island Zone, typically described as the northern extension of the Aleutian megathrust but which may be a forming suture acting as a deformation backstop for the converging Yakutat and North American plates. Profiles across the Pamplona Zone, the current Yakutat-North America deformation front, will further constrain relative timing of structural development and the depth of deformation on the broad folds and thrust faults that comprise the area. This new dataset will allow further insight into regional tectonics of the St. Elias region as well as provide more detail regarding the development of the south Alaskan margin during major Plio-Pleistocene glacial- interglacial periods.

  15. Enhanced hazard assessment of a steep limestone rock slope above the federal road B 305

    NASA Astrophysics Data System (ADS)

    Sellmeier, Bettina; Krautblatter, Michael; Thuro, Kurosch

    2013-04-01

    Rock fall events of the last years show that in many cases infrastructure like railways, highways and roads are affected, as has been demonstrated by the rock fall in Gurtnellen on June 5th, 2012 with one casualty and on Nov. 14th, 2012. To minimize the rock fall risk it is necessary to analyze, assess and anticipate the processes by means of rock fall modeling. Up to now it is common to perform the determination of input parameters using fact sheets referring to the requirements of the chosen code in terms of input parameters (Dorren 2010, GEOTEST 2006). In many cases it is not sufficient to only attend to the common parameter lists, but it is required to collect enhanced data. In the current project it has been worked out that it is essential to think about the following accessory questions when performing rock fall modeling: • How can we achieve additional knowledge about block sizes by acquiring enhanced data considering the source areas? • How can we round off the input data for rock fall modeling by performing kinematic analysis? • To which extent can the approaches of Barton & Choubey (1977) be an amendment to rockfall modeling? These questions are addressed in a steep forested limestone slope that extends above the federal road B 305 near Ramsau in the Bavarian Alps, 30 km southwest of Salzburg. The extension of the source area was mapped combining the information of hillshades generated of a 1m-DTM and fieldwork. During the project we performed a detailed analysis of the discontinuities in the source area, which implies the evaluation of discontinuity patterns as well as a kinematic analysis (Markland 1972, Talobre 1957). In a second step, we focused on a key object, a single block subject to planar failure, where it was possible to directly enter the detachment surface. We performed an accurate mapping of the release surface with special regard to fracture roughness as well as rock bridges (Barton & Choubey 1977, ISRM 1978 and Woszdilo 1989). The

  16. Bed load transport in a very steep mountain stream (Riedbach, Switzerland): Measurement and prediction

    NASA Astrophysics Data System (ADS)

    Schneider, Johannes M.; Rickenmann, Dieter; Turowski, Jens M.; Schmid, Bastian; Kirchner, James W.

    2016-12-01

    Compared to lower-gradient channels, steep mountain streams typically have rougher beds and shallower flow depths, making macro-scale flow resistance (due to, e.g., immobile boulders and irregular bedforms) more important as controls on sediment transport. The marked differences in hydraulics, flow resistance, and grain mobility between steep and lower-gradient streams raise the question of whether the same equations can predict bed load transport rates across wide ranges of channel gradients. We studied a steep, glacier-fed mountain stream (Riedbach, Ct. Valais, Switzerland) that provides a natural experiment for exploring how stream gradients affect bed load transport rates. The streambed gradient increases over a 1 km stream reach by roughly one order of magnitude (from 3% to 38%), while flow discharge and width remain approximately constant. Sediment transport rates were determined in the 3% reach using Bunte bed load traps and in the 38% reach using the Swiss plate geophone system. Despite a ten-fold increase in bed gradient, bed load transport rates did not increase substantially. Observed transport rates for these two very different bed gradients could be predicted reasonably well by using a flow resistance partitioning approach to account for increasing bed roughness (D84 changes from 0.17 m to 0.91 m) within a fractional bed load transport equation. This suggests that sediment transport behavior across this large range of steep slopes agrees with patterns established in previous studies for both lower-gradient and steep reaches, and confirms the applicability of the flow resistance and bed load transport equations at very steep slopes.

  17. Effects of low frequency ultrasonic treatment on the maturation of steeped greengage wine.

    PubMed

    Zheng, Xinhua; Zhang, Min; Fang, Zhongxiang; Liu, Yaping

    2014-11-01

    To accelerate wine maturation, low frequency ultrasonic waves of 28 kHz and 45 kHz were used to treat the steeped greengage wine. The contents of total acid, total ester, fusel oils and the wine chromaticity were determined before and after the ultrasonic treatment. The volatile compounds were analysed by GC-MS method, and the sensory quality was evaluated by panelist. The results indicated that ultrasonic treatment of the steeped greengage wine at 45 kHz 360 W for 30 min was effective to accelerate the aging process, where the fusel oils and alcohol compounds were significantly reduced and acid and ester compounds were significantly increased.

  18. Bedload transport in steep glacier-fed streams: from incipient motion to floods

    NASA Astrophysics Data System (ADS)

    Comiti, Francesco; Dell'Agnese, Andrea; Lucia, Ana; Vignoli, Gianluca; Simoni, Silvia; Bertoldi, Walter; Mao, Luca; Macconi, Pierpaolo; Mazzorana, Bruno; Dinale, Roberto

    2015-04-01

    The current understanding of bedload dynamics in mountain channels is rather scarce, and the capability to predict it over a range of discharges and under different morphological conditions is still very poor despite the headways made during the last decade. Indeed, there has been an increased recognition of the highly stochastic nature of bedload transport in steep streams, especially at low to medium flows (i.e. up to ordinary events). On the other hand, considerable efforts have been made to model the effective energy available for bedload in steep channels, in order to reduce the large overestimation in bedload rates produced by transport capacity equations. Nonetheless, because high-gradient channels are notoriously sediment supply-limited, largely varying bedload rates can be observed at the same stream cross-section under nearly identical morphological and hydraulic conditions, as a consequence of different sediment supply regimes/events. Therefore, the use of a single bedload transport equation even for the same stream is becoming strongly questioned by researchers, whereas most river agencies and consultants - and numerical models - still rely on "classical" transport capacity equations. Remarkably, glacial streams offer the possibility to investigate how seasonal changes in sediment supply at the basin scale - deriving from the periglacial and glacial areas - affects bedload transport rates in the main channel. However, little quantitative bedload data from these systems are available. This contribution intends to share the recent results obtained in two glaciarized basins in the Eastern Italian Alps, which range from about 10 km2 (upper Saldur river basin) to 130 km2 (Sulden river basin) in drainage area. Different monitoring methodologies encompassing PIT-tagged clasts tracking (by both portable and stationary antennas), geophone plates, acoustic pipe sensor and direct sampling by portable traps have been deployed in these two mountain streams. Our

  19. Energy spectrum based calculation of the half and the tenth value layers for brachytherapy sources using a semiempirical parametrized mass attenuation coefficient formulism

    SciTech Connect

    Yue, Ning J.

    2008-06-15

    As different types of radionuclides (e.g., {sup 131}Cs source) are introduced for clinical use in brachytherapy, the question is raised regarding whether a relatively simple method exists for the derivation of values of the half value layer (HVL) or the tenth value layer (TVL). For the radionuclide that has been clinically used for years, such as {sup 125}I and {sup 103}Pd, the sources have been manufactured and marketed by several vendors with different designs and structures. Because of the nature of emission of low energy photons for these radionuclides, energy spectra of the sources are very dependent on their individual designs. Though values of the HVL or the TVL in certain commonly used shielding materials are relatively small for these low energy photon emitting sources, the question remains how the variations in energy spectra affect the HVL (or TVL) values and whether these values can be calculated with a relatively simple method. A more fundamental question is whether a method can be established to derive the HVL (TVL) values for any brachytherapy sources and for different materials in a relatively straightforward fashion. This study was undertaken to answer these questions. Based on energy spectra, a well established semiempirical mass attenuation coefficient computing scheme was utilized to derive the HVL (TVL) values of different materials for different types of brachytherapy sources. The method presented in this study may be useful to estimate HVL (TVL) values of different materials for brachytherapy sources of different designs and containing different radionuclides.

  20. Energy spectrum based calculation of the half and the tenth value layers for brachytherapy sources using a semiempirical parametrized mass attenuation coefficient formulism.

    PubMed

    Yue, Ning J

    2008-06-01

    As different types of radionuclides (e.g., 131Cs source) are introduced for clinical use in brachytherapy, the question is raised regarding whether a relatively simple method exists for the derivation of values of the half value layer (HVL) or the tenth value layer (TVL). For the radionuclide that has been clinically used for years, such as 125I and 103Pd, the sources have been manufactured and marketed by several vendors with different designs and structures. Because of the nature of emission of low energy photons for these radionuclides, energy spectra of the sources are very dependent on their individual designs. Though values of the HVL or the TVL in certain commonly used shielding materials are relatively small for these low energy photon emitting sources, the question remains how the variations in energy spectra affect the HVL (or TVL) values and whether these values can be calculated with a relatively simple method. A more fundamental question is whether a method can be established to derive the HVL (TVL) values for any brachytherapy sources and for different materials in a relatively straightforward fashion. This study was undertaken to answer these questions. Based on energy spectra, a well established semiempirical mass attenuation coefficient computing scheme was utilized to derive the HVL (TVL) values of different materials for different types of brachytherapy sources. The method presented in this study may be useful to estimate HVL (TVL) values of different materials for brachytherapy sources of different designs and containing different radionuclides.

  1. The radio spectral energy distribution of infrared-faint radio sources

    NASA Astrophysics Data System (ADS)

    Herzog, A.; Norris, R. P.; Middelberg, E.; Seymour, N.; Spitler, L. R.; Emonts, B. H. C.; Franzen, T. M. O.; Hunstead, R.; Intema, H. T.; Marvil, J.; Parker, Q. A.; Sirothia, S. K.; Hurley-Walker, N.; Bell, M.; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Callingham, J. R.; Deshpande, A. A.; Dwarakanath, K. S.; For, B.-Q.; Greenhill, L. J.; Hancock, P.; Hazelton, B. J.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A. D.; Kaplan, D. L.; Lenc, E.; Lonsdale, C. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Morgan, J.; Oberoi, D.; Offringa, A.; Ord, S. M.; Prabu, T.; Procopio, P.; Udaya Shankar, N.; Srivani, K. S.; Staveley-Smith, L.; Subrahmanyan, R.; Tingay, S. J.; Wayth, R. B.; Webster, R. L.; Williams, A.; Williams, C. L.; Wu, C.; Zheng, Q.; Bannister, K. W.; Chippendale, A. P.; Harvey-Smith, L.; Heywood, I.; Indermuehle, B.; Popping, A.; Sault, R. J.; Whiting, M. T.

    2016-10-01

    Context. Infrared-faint radio sources (IFRS) are a class of radio-loud (RL) active galactic nuclei (AGN) at high redshifts (z ≥ 1.7) that are characterised by their relative infrared faintness, resulting in enormous radio-to-infrared flux density ratios of up to several thousand. Aims: Because of their optical and infrared faintness, it is very challenging to study IFRS at these wavelengths. However, IFRS are relatively bright in the radio regime with 1.4 GHz flux densities of a few to a few tens of mJy. Therefore, the radio regime is the most promising wavelength regime in which to constrain their nature. We aim to test the hypothesis that IFRS are young AGN, particularly GHz peaked-spectrum (GPS) and compact steep-spectrum (CSS) sources that have a low frequency turnover. Methods: We use the rich radio data set available for the Australia Telescope Large Area Survey fields, covering the frequency range between 150 MHz and 34 GHz with up to 19 wavebands from different telescopes, and build radio spectral energy distributions (SEDs) for 34 IFRS. We then study the radio properties of this class of object with respect to turnover, spectral index, and behaviour towards higher frequencies. We also present the highest-frequency radio observations of an IFRS, observed with the Plateau de Bure Interferometer at 105 GHz, and model the multi-wavelength and radio-far-infrared SED of this source. Results: We find IFRS usually follow single power laws down to observed frequencies of around 150 MHz. Mostly, the radio SEDs are steep (α < -0.8; %), but we also find ultra-steep SEDs (α < -1.3; %). In particular, IFRS show statistically significantly steeper radio SEDs than the broader RL AGN population. Our analysis reveals that the fractions of GPS and CSS sources in the population of IFRS are consistent with the fractions in the broader RL AGN population. We find that at least % of IFRS contain young AGN, although the fraction might be significantly higher as suggested by

  2. Faraday rotation from magnesium II absorbers toward polarized background radio sources

    SciTech Connect

    Farnes, J. S.; O'Sullivan, S. P.; Corrigan, M. E.; Gaensler, B. M.

    2014-11-01

    Strong singly ionized magnesium (Mg II) absorption lines in quasar spectra typically serve as a proxy for intervening galaxies along the line of sight. Previous studies have found a correlation between the number of these Mg II absorbers and the Faraday rotation measure (RM) at ≈5 GHz. We cross-match a sample of 35,752 optically identified non-intrinsic Mg II absorption systems with 25,649 polarized background radio sources for which we have measurements of both the spectral index and RM at 1.4 GHz. We use the spectral index to split the resulting sample of 599 sources into flat-spectrum and steep-spectrum subsamples. We find that our flat-spectrum sample shows significant (∼3.5σ) evidence for a correlation between Mg II absorption and RM at 1.4 GHz, while our steep-spectrum sample shows no such correlation. We argue that such an effect cannot be explained by either luminosity or other observational effects, by evolution in another confounding variable, by wavelength-dependent polarization structure in an active galactic nucleus, by the Galactic foreground, by cosmological expansion, or by partial coverage models. We conclude that our data are most consistent with intervenors directly contributing to the Faraday rotation along the line of sight, and that the intervening systems must therefore have coherent magnetic fields of substantial strength ( B-bar =1.8±0.4 μG). Nevertheless, the weak nature of the correlation will require future high-resolution and broadband radio observations in order to place it on a much firmer statistical footing.

  3. Influence of starch steeping period on dimensionless disintegration values of a paracetamol tablet formulation.

    PubMed

    Alebiowu, Gbenga; Adeyemi, Ayoade O

    2009-01-01

    In this study, tapioca starches obtained after different steeping periods, i.e. TS 24, TS 48 and TS 72, were used as disintegrants with corn starch BP as the standard disintegrant in a paracetamol tablet formulation. Two dimensionless disintegration quantities, T(N) and T(C) were used in the determination of the influence that steeping period of starch disintegrant would have on the crushing strength friability-disintegration time ratio (CSFR/DT). These quantities were used to assess the influence of steeping period, relative density and disintegrant concentration on CSFR/DT as well as to compare disintegrant efficiency. The results suggest that the CSFR/DT is more dependent on the disintegrant concentration than on steeping period and relative density. The study further showed that TS 72 is a more reliable disintegrant because its activity would not be influenced by changes in relative density of tablets. This work concludes that the T(N) would be more useful for quantitative assessment while T(C) is more relevant for qualitative assessment.

  4. X-ray refraction effect and density determination of steep-gradient, high-density plasma

    NASA Astrophysics Data System (ADS)

    Miyanaga, N.; Kato, Y.; Yamanaka, C.

    1982-12-01

    X-ray defraction due to the steep density gradient of a laser-produced plasma has been observed. Distribution of the density gradient was determined from the measured refraction angle. Estimation of the radial density profile and the density scale length in the high-density region near the ablation surface are presented.

  5. Inactivation of tannins in milled sorghum grain through steeping in dilute NaOH solution.

    PubMed

    Adetunji, Adeoluwa I; Duodu, Kwaku G; Taylor, John R N

    2015-05-15

    Steeping milled sorghum in up to 0.4% NaOH was investigated as a method of tannin inactivation. NaOH steeping substantially reduced assayable total phenols and tannins in both Type III and Type II sorghums and with Type III sorghum caused a 60-80% reduction in α-amylase inhibition compared to a 20% reduction by water steeping. NaOH treatment also reduced starch liquefaction time and increased free amino nitrogen. Type II tannin sorghum did not inhibit α-amylase and consequently the NaOH treatment had no effect. HPLC and LC-MS of the tannin extracts indicated a general trend of increasing proanthocyanidin/procyanidin size with increasing NaOH concentration and steeping time, coupled with a reduction in total area of peaks resolved. These show that the NaOH treatment forms highly polymerised tannin compounds, too large to assay and to interact with the α-amylase. NaOH pre-treatment of Type III sorghums could enable their utilisation in bioethanol production.

  6. Contour Planting: A Strategy to Reduce Soil Erosion on Steep Slopes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Practices that combine GPS-based guidance for terrain contouring and tillage for runoff detention have potential to increase water infiltration and reduce runoff. The objective of this study was to investigate contour planting as a means to reduce soil erosion on steep slopes of the Columbia Platea...

  7. Does WEPP meet the specificity of soil erosion in steep mountain regions?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We chose the USDA-ARS-WEPP model (Water Erosion Prediction Project) to describe the soil erosion in the Urseren valley (Central Switzerland) as it seems to be one of the most promising models for steep mountain environments. Crucial model parameters were determined in the field (slope, plant species...

  8. Slope, Rate of Change, and Steepness: Do Students Understand These Concepts?

    ERIC Educational Resources Information Center

    Teuscher, Dawn; Reys, Robert E.

    2010-01-01

    How do mathematics teachers introduce the concepts of slope, rate of change, and steepness in their classrooms? Do students understand these concepts as interchangeable or regard them as three different ideas? In this article, the authors report the results of a study of high school Advanced Placement (AP) Calculus students who displayed…

  9. Erosion risk assessment of controlled burning of grasses established on steep slopes

    NASA Astrophysics Data System (ADS)

    Gyasi-Agyei, Yeboah

    2006-02-01

    It is a standard practice to establish grasses on steep slopes (batters) of embankments and cuttings to minimise erosion problems. However, the increase in grass density (high biomass) on the steep slopes poses a greater risk of fire. Controlled burning is a common fuel hazard reduction program employed to minimise the fire risks. The increased risk of erosion on the steep slopes after controlled burning has received little attention if any. This paper assesses the erosion risks associated with controlled burning of grasses established on steep slopes. Grasses, with and without the aid of waste ballast rock mulch, were established on 10 m wide railway embankment batter experiment plots. Two-and-a-half years after the grass establishment, selected plots were controlled burned. Runoff and soil loss from the experimental plots were monitored throughout the 3½-year period of the experiment. After one year the grass cover on the burned plots has hardly exceeded 60%, far below the average pre-burn levels of about 80%. All treatments achieved an incredible soil loss reduction of over 95% (compared with the bare scenario) without controlled burning at the end of the 3½-year period. This percentage value was decreased numerically by 14 where controlled burning was implemented. Compared with the 100% grass cover treatment, runoff rates tripled while erosion rates increased by nine-fold for the waste ballast treatment, and 17-fold for the non-waste ballast treatment, during the first year following controlled burning.

  10. PI3-kinase signaling contributes to orientation in shallow gradients and enhances speed in steep chemoattractant gradients.

    PubMed

    Bosgraaf, Leonard; Keizer-Gunnink, Ineke; Van Haastert, Peter J M

    2008-11-01

    Dictyostelium cells that chemotax towards cAMP produce phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P(3)] at the leading edge, which has been implicated in actin reorganization and pseudopod extension. However, in the absence of PtdIns(3,4,5)P(3) signaling, cells will chemotax via alternative pathways. Here we examined the potential contribution of PtdIns(3,4,5)P(3) to chemotaxis of wild-type cells. The results show that steep cAMP gradients (larger than 10% concentration difference across the cell) induce strong PtdIns(3,4,5)P(3) patches at the leading edge, which has little effect on the orientation but strongly enhances the speed of the cell. Using a new sensitive method for PtdIns(3,4,5)P(3) detection that corrects for the volume of cytosol in pixels at the boundary of the cell, we show that, in shallow cAMP gradient (less than 5% concentration difference across the cell), PtdIns(3,4,5)P(3) is still somewhat enriched at the leading edge. Cells lacking PI3-kinase (PI3K) activity exhibit poor chemotaxis in these shallow gradients. Owing to the reduced speed and diminished orientation of the cells in steep and shallow gradients, respectively, cells lacking PtdIns(3,4,5)P(3) signaling require two- to six-fold longer times to reach a point source of chemoattractant compared with wild-type cells. These results show that, although PI3K signaling is dispensable for chemotaxis, it gives the wild type an advantage over mutant cells.

  11. Morphometric and meteorological controls on recent snow avalanche distribution and activity at hillslopes in steep mountain valleys in western Norway

    NASA Astrophysics Data System (ADS)

    Laute, Katja; Beylich, Achim A.

    2014-08-01

    Snow avalanches are common phenomena in Norway. Controlling factors of snow avalanche distribution and activity, and the relative importance of snow avalanches regarding contemporary sedimentary mass transfers were explored within two steep, parabolic-shaped and glacier-connected tributary valleys (Erdalen and Bødalen) in western Norway. Mapping of distribution, extent and the entire path lengths of snow avalanches was combined with spatial data analysis (GIS and DEM computing) of morphometric controls. The timing and frequency of snow avalanches were explored by correlating meteorological data with high-resolution monitoring data of snow avalanche events. Sediment masses annually transferred by snow avalanches along hillslopes and from hillslopes into stream channels were estimated. A high inter-annual variability of avalanche activity and a wide spectrum of avalanche sizes and types ranging from small to extreme-sized events were found for the four-year investigation period 2009-2012. Spatial distribution of snow avalanches is governed by the topographical factors valley orientation, slope aspect, relative slope height and rockwall morphometry whereas timing and frequency of snow avalanches are controlled by snowfall intensity, periods with strong winds combined with a prevalent wind direction or sharp air temperature changes within short time periods. Snow avalanches represent one of the dominant denudational processes and have a high relative importance regarding sedimentary mass transfers within the two mountain valleys Erdalen and Bødalen in western Norway.

  12. Exploratory 5-micron spectrum of Uranus

    SciTech Connect

    Orton, G.S.; Kaminski, C.D.

    1989-01-01

    The intensity peak at 4.8 microns characterizing the spectrum observed for the disk of Uranus near 5 microns, in June 1987, exhibits steep declines at shorter and longer wavelength. An exploratory discussion is presented of various models in view of these data; it is noted that some component of the radiation must originate near the 140 K atmospheric irrespective of the radiation's origin in sunlight or thermal emission; physical considerations dictate that it be at least partly thermal in origin. One model consistent with the data requires the presence of a cloud top at the 8-bar level. 30 references.

  13. Pseudo 3-D P wave refraction seismic monitoring of permafrost in steep unstable bedrock

    NASA Astrophysics Data System (ADS)

    Krautblatter, Michael; Draebing, Daniel

    2014-02-01

    permafrost in steep rock walls can cause hazardous rock creep and rock slope failure. Spatial and temporal patterns of permafrost degradation that operate at the scale of instability are complex and poorly understood. For the first time, we used P wave seismic refraction tomography (SRT) to monitor the degradation of permafrost in steep rock walls. A 2.5-D survey with five 80 m long parallel transects was installed across an unstable steep NE-SW facing crestline in the Matter Valley, Switzerland. P wave velocity was calibrated in the laboratory for water-saturated low-porosity paragneiss samples between 20°C and -5°C and increases significantly along and perpendicular to the cleavage by 0.55-0.66 km/s (10-13%) and 2.4-2.7 km/s (>100%), respectively, when freezing. Seismic refraction is, thus, technically feasible to detect permafrost in low-porosity rocks that constitute steep rock walls. Ray densities up to 100 and more delimit the boundary between unfrozen and frozen bedrock and facilitate accurate active layer positioning. SRT shows monthly (August and September 2006) and annual active layer dynamics (August 2006 and 2007) and reveals a contiguous permafrost body below the NE face with annual changes of active layer depth from 2 to 10 m. Large ice-filled fractures, lateral onfreezing of glacierets, and a persistent snow cornice cause previously unreported permafrost patterns close to the surface and along the crestline which correspond to active seasonal rock displacements up to several mm/a. SRT provides a geometrically highly resolved subsurface monitoring of active layer dynamics in steep permafrost rocks at the scale of instability.

  14. Egalitarian despots: hierarchy steepness, reciprocity and the grooming-trade model in wild chimpanzees, Pan troglodytes

    PubMed Central

    Kaburu, Stefano S. K.; Newton-Fisher, Nicholas E.

    2014-01-01

    Biological market theory models the action of natural selection as a marketplace in which animals are viewed as traders with commodities to offer and exchange. Studies of female Old World monkeys have suggested that grooming might be employed as a commodity to be reciprocated or traded for alternative services, yet previous tests of this grooming-trade model in wild adult male chimpanzees have yielded mixed results. Here we provide the strongest test of the model to date for male chimpanzees: we use data drawn from two social groups (communities) of chimpanzees from different populations and give explicit consideration to variation in dominance hierarchy steepness, as such variation results in differing conditions for biological markets. First, analysis of data from published accounts of other chimpanzee communities, together with our own data, showed that hierarchy steepness varied considerably within and across communities and that the number of adult males in a community aged 20–30 years predicted hierarchy steepness. The two communities in which we tested predictions of the grooming-trade model lay at opposite extremes of this distribution. Second, in accord with the grooming-trade model, we found evidence that male chimpanzees trade grooming for agonistic support where hierarchies are steep (despotic) and consequent effective support is a rank-related commodity, but not where hierarchies are shallow (egalitarian). However, we also found that grooming was reciprocated regardless of hierarchy steepness. Our findings also hint at the possibility of agonistic competition, or at least exclusion, in relation to grooming opportunities compromising the free market envisioned by biological market theory. Our results build on previous findings across chimpanzee communities to emphasize the importance of reciprocal grooming exchanges among adult male chimpanzees, which can be understood in a biological markets framework if grooming by or with particular individuals is

  15. Carbapenems Versus Piperacillin-Tazobactam for Bloodstream Infections of Nonurinary Source Caused by Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae.

    PubMed

    Ofer-Friedman, Hadas; Shefler, Coral; Sharma, Sarit; Tirosh, Amit; Tal-Jasper, Ruthy; Kandipalli, Deepthi; Sharma, Shruti; Bathina, Pradeep; Kaplansky, Tamir; Maskit, Moran; Azouri, Tal; Lazarovitch, Tsilia; Zaidenstein, Ronit; Kaye, Keith S; Marchaim, Dror

    2015-08-01

    A recent, frequently quoted study has suggested that for bloodstream infections (BSIs) due to extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL) Escherichia coli, treatment with β-lactam/β-lactamase inhibitors (BLBLIs) might be equivalent to treatment with carbapenems. However, the majority of BSIs originate from the urinary tract. A multicenter, multinational efficacy analysis was conducted from 2010 to 2012 to compare outcomes of patients with non-urinary ESBL BSIs who received a carbapenem (69 patients) vs those treated with piperacillin-tazobactam (10 patients). In multivariate analysis, therapy with piperacillin-tazobactam was associated with increased 90-day mortality (adjusted odds ratio, 7.9, P=.03). For ESBL BSIs of a non-urinary origin, carbapenems should be considered a superior treatment to BLBLIs.

  16. Using Local Radiation MHD Simulations to Attempt to Understand the Very High/Steep Power Law State of Black Hole X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Blaes, Omer

    Stellar mass black holes in certain types of binary systems accrete matter from their companion stars through rotating, turbulent flows known as accretion disks. These disks are observed by space X-ray missions to have a number of distinct spectral/variability states, the most mysterious one being the very high/steep power law state that generally occurs at very high luminosities. This state is particularly interesting as it exhibits unique quasi-periodic oscillations observed in the X-rays that, if understood, might help us directly measure the properties of the black hole spacetime. Radiation pressure is an important physical process at such high luminosities, and modifies the character of the accretion disk in a number of unique ways. One of the ways that it does this is that it enables turbulent speeds in the disk to exceed thermal speeds of electrons, thereby introducing a completely new radiation process - turbulent Comptonization. This radiation process is promising for explaining the unique spectral characteristics of the very high/steep power law state. We will test this hypothesis by making detailed calculations of the emergent radiation spectrum from numerical simulation data of the turbulence in local patches of the disk at high levels of radiation pressure. These will be the first detailed theoretical calculations of turbulent Comptonization, which should be an important process for modeling NASA data from high luminosity black hole accretion. We hope that this will shed light on the nature of the mysterious very high/steep power law state. The research will form the basis of the PhD thesis of a graduate student, in line with NASA's educational and training objectives.

  17. Radio spectrum surveillance station

    NASA Technical Reports Server (NTRS)

    Hersey, D. R.

    1979-01-01

    The paper presents a general and functional description of a low-cost surveillance station designed as the first phase of NASA's program to develop a radio spectrum surveillance capability for deep space stations for identifying radio frequency interference sources. The station described has identified several particular interferences and is yielding spectral signature data which, after cataloging, will serve as a library for rapid identification of frequently observed interference. Findings from the use of the station are discussed.

  18. Bedload Transport on Steep Slopes with Coupled Modeling Based on the Discrete Element Method

    NASA Astrophysics Data System (ADS)

    Chauchat, J.; Maurin, R.; Chareyre, B.; Frey, P.

    2014-12-01

    After more than a century of research, a clear understanding of the physical processes involved in sediment transport problems is still lacking. In particular, modeling of intergranular interactions and fluid-particle interactions in bedload transport need to be improved. In this contribution, we propose a simple numerical model coupling a Discrete Element Method (DEM) for the grain dynamics with a simple 1D vertical fluid phase model inspired from the two-phase approach [1] in order to contribute to this open question. The Reynolds stress is parameterized by a mixing length model which depends on the integral of the grain volume fraction. The coupling between the grains and the fluid phase is essentially achieved through buoyancy and drag forces. The open source DEM code Yade [2] is used with a linear spring-dashpot contact law that allows the description of the behavior of the particles from the quasi-static to the dynamical state. The model is compared with classical results [3] and with particle-scale experimental results obtained in the quasi-2D flume at IRSTEA, Grenoble [4]. We discuss the closures of the model and the sensitivity to the different physical and numerical parameters. [1] Revil-Baudard, T. and J. Chauchat. A two-phase model for sheet flow regime based on dense granular flow rheology. Journal of Geophysical Research: Oceans, 118(2):619-634, 2013. [2] Šmilauer V. , E. Catalano, B. Chareyre, S. Dorofeenko, J. Duriez, A. Gladky, J. Kozicki, C . Modenese, L. Scholtès, L. Sibille, J. Str.nský, and K. Thoeni. Yade Documentation (V. Šmilauer, ed.), The Yade Project, 1st ed., http://yade-dem.org/doc/., 2010. [3] Meyer-Peter, E. and R. Müller. Formulas for bed-load transport. In Proc. 2nd Meeting, pages 39-64. IAHR, 1948. [4] Frey, P. Particle velocity and concentration profiles in bedload experiments on a steep slope. Earth Surface Processes and Landforms, 39(5):646-655, 2014.

  19. Transport and Export of Coarse Particulate Organic Matter (CPOM) in Steep Streams

    NASA Astrophysics Data System (ADS)

    Bunte, K.; Swingle, K. W.; Turowski, J. M.; Abt, S. R.; Cenderelli, D. A.

    2015-12-01

    Coarse particulate organic material >1 mm (CPOM) comprising mainly leaves, needles, cones, twigs, and decaying wood pieces is an energy source in headwater ecosystems, and CPOM transport of is one form of watershed carbon export. However, sampling methods for instantaneous CPOM transport rates and annual loads are not well developed, and hence not much is known about annual CPOM export from high energy, forested mountain streams. CPOM transport samples were collected over one-month snowmelt highflow seasons in two high-elevation, subalpine, Rocky Mountains streams with snowmelt regimes as well as in a montane torrent in the Swiss Pre-Alps with a pluvio-nival regime. Basin areas ranged from 1 to 13 km2. Bedload traps and automated hanging baskets installed at an overfall, developed for sampling gravel bedload, proved suitable for sampling CPOM transport. Bedload traps with 0.3 by 0.2 m openings are typically deployed for an hour at a time during wadeable flows, collect samples back-to-back, and may trap volumes of up to 20 liters in the attached 1.4 m long nets. At the Swiss site, hanging baskets with a 1 m3 volume are deployed at an overfall in unwadeable flows, and bedload traps in wadeable flows. When flow overtopped bedload traps, CPOM transport rates were adjusted to estimate and add the unsampled CPOM portion traveling higher in the water column; when nets overfilled, CPOM transport rate were adjusted for the reduction in captured transport. CPOM transport rates in consecutive samples were well related to flow but showed pronounced hysteresis over diurnal fluctuations of flow, between consecutive days, and over the rising and falling limbs of the high-flow season. Hysteresis effects require intensive sampling and use of separate rating curves for all rising and falling limbs in order to compute annual CPOM load. Annual CPOM export for the two Rocky Mountain streams was 2.7 and 4 kg/ha/year, but both streams exported 6.5 and 6.6 kg/ha/year per forested portion

  20. Electromagnetic spectrum management system

    DOEpatents

    Seastrand, Douglas R.

    2017-01-31

    A system for transmitting a wireless countermeasure signal to disrupt third party communications is disclosed that include an antenna configured to receive wireless signals and transmit wireless counter measure signals such that the wireless countermeasure signals are responsive to the received wireless signals. A receiver processes the received wireless signals to create processed received signal data while a spectrum control module subtracts known source signal data from the processed received signal data to generate unknown source signal data. The unknown source signal data is based on unknown wireless signals, such as enemy signals. A transmitter is configured to process the unknown source signal data to create countermeasure signals and transmit a wireless countermeasure signal over the first antenna or a second antenna to thereby interfere with the unknown wireless signals.

  1. Multifrequency VLA observations of PKS 0745 - 191 - The archetypal 'cooling flow' radio source?

    NASA Technical Reports Server (NTRS)

    Baum, S. A.; O'Dea, C. P.

    1991-01-01

    Ninety-, 20-, 6- and 2-cm VLA observations of the high-radio-luminosity cooling-flow radio source PKS 0745 - 191 are presented. The radio source was found to have a core with a very steep spectrum (alpha is approximately -1.5) and diffuse emission with an even steeper spectrum (alpha is approximately -1.5 to -2.3) without clear indications of the jets, hotspots, or double lobes found in the other radio sources of comparable luminosity. It is inferred that the energy to power the radio source comes from the central engine, but the source's structure may be heavily influenced by the past history of the galaxy and the inflowing intracluster medium. It is shown that, while the radio source is energetically unimportant for the cluster as a whole, it is important on the scale of the cooling flow. The mere existence of cosmic rays and magnetic fields within a substantial fraction of the volume inside the cooling radius has important consequences for cooling-flow models.

  2. Multifrequency VLA observations of PKS 0745 - 191 - The archetypal 'cooling flow' radio source?

    NASA Astrophysics Data System (ADS)

    Baum, S. A.; O'Dea, C. P.

    1991-06-01

    Ninety-, 20-, 6- and 2-cm VLA observations of the high-radio-luminosity cooling-flow radio source PKS 0745 - 191 are presented. The radio source was found to have a core with a very steep spectrum (alpha is approximately -1.5) and diffuse emission with an even steeper spectrum (alpha is approximately -1.5 to -2.3) without clear indications of the jets, hotspots, or double lobes found in the other radio sources of comparable luminosity. It is inferred that the energy to power the radio source comes from the central engine, but the source's structure may be heavily influenced by the past history of the galaxy and the inflowing intracluster medium. It is shown that, while the radio source is energetically unimportant for the cluster as a whole, it is important on the scale of the cooling flow. The mere existence of cosmic rays and magnetic fields within a substantial fraction of the volume inside the cooling radius has important consequences for cooling-flow models.

  3. Streptomyces misionensis PESB-25 Produces a Thermoacidophilic Endoglucanase Using Sugarcane Bagasse and Corn Steep Liquor as the Sole Organic Substrates

    PubMed Central

    Rezende, Raquel de Carvalho; Gravina-Oliveira, Mônica Pires; Pereira, Pedro Henrique Freitas; do Nascimento, Rodrigo Pires; Bon, Elba Pinto da Silva; Macrae, Andrew; Coelho, Rosalie Reed Rodrigues

    2013-01-01

    Streptomyces misionensis strain PESB-25 was screened and selected for its ability to secrete cellulases. Cells were grown in a liquid medium containing sugarcane bagasse (SCB) as carbon source and corn steep liquor (CSL) as nitrogen source, whose concentrations were optimized using response surface methodology (RSM). A peak of endoglucanase accumulation (1.01 U·mL−1) was observed in a medium with SCB 1.0% (w/v) and CSL 1.2% (w/v) within three days of cultivation. S. misionensis PESB-25 endoglucanase activity was thermoacidophilic with optimum pH and temperature range of 3.0 to 3.6 and 62° to 70°C, respectively. In these conditions, values of 1.54 U mL−1 of endoglucanase activity were observed. Moreover, Mn2+ was demonstrated to have a hyperactivating effect on the enzyme. In the presence of MnSO4 (8 mM), the enzyme activity increased threefold, up to 4.34 U·mL−1. Mn2+ also improved endoglucanase stability as the catalyst retained almost full activity upon incubation at 50°C for 4 h, while in the absence of Mn2+, enzyme activity decreased by 50% in this same period. Three protein bands with endoglucanase activity and apparent molecular masses of 12, 48.5 and 119.5 kDa were detected by zymogram. PMID:23586048

  4. Design and manufacture of a bandpass filter with high transmittance and steep edge on both sides

    NASA Astrophysics Data System (ADS)

    Wang, Ruisheng; Lü, Shaobo; Yin, Xiaojun; Zhao, Shuaifeng; Sun, Yan

    2016-01-01

    By using Nb2O5 and SiO2 as the coating material, a 152 layers (12 cavities) bandpass film stack with steep edge on both sides was designed. Multiple thickness control methods, including direct optical monitoring control and time control were used in coating strategy. To confirm the feasibility of this coating strategy, a process simulation was performed using Simulator software, and the simulation result indicated that relative thickness errors for all layers were less than ±0.1%. A bandpass filter with this film stack on one side was manufactured by using a plasma assisted reactive magnetic sputtering coating machine. The measuring result shows that the peak transmittance of the filter (without AR on backside) is up to 95.4%, and the steepness of both blocking slope are less than λ/100.

  5. Topographic optical profilometry of steep slope micro-optical transparent surfaces.

    PubMed

    Antón, Juan Carlos Martínez; Alonso, Jose; Pedrero, Jose Antonio Gómez

    2015-04-06

    Optical profilometers based on light reflection may fail at surfaces presenting steep slopes and highly curved features. Missed light, interference and diffraction at steps, peaks and valleys are some of the reasons. Consequently, blind areas or profile artifacts may be observed when using common reflection micro-optical profilometers (confocal, scanning interferometers, etc…). The Topographic Optical Profilometry by Absorption in Fluids (TOPAF) essentially avoids these limitations. In this technique an absorbing fluid fills the gap between a reference surface and the surface to profile. By comparing transmission images at two different spectral bands we obtain a reliable topographic map of the surface. In this contribution we develop a model to obtain the profile under micro-optical observation, where high numerical aperture (NA) objectives are mandatory. We present several analytical and experimental results, validating the technique's capabilities for profiling steep slopes and highly curved micro-optical surfaces with nanometric height resolution.

  6. Steep subthreshold slope characteristics of body tied to gate NMOSFET in partially depleted SOI

    NASA Astrophysics Data System (ADS)

    Song, Lei; Hu, Zhiyuan; Liu, Zhangli; Xin, Haiwei; Zhang, Zhengxuan; Zou, Shichang

    2017-04-01

    A new body tied to gate (BTG) n-channel metal-oxide-semiconductor field-effect-transistor (NMOSFET) with a diode in partially depleted SOI (PD SOI) is proposed and investigated. We first compare the transfer and output characteristics between the regular and BTG NMOSFETs with grounded body and floating body. The steep subthreshold slope (<6 mV/dec) and low OFF current (∼0.01 pA/μm) of the BTG NMOSFET with floating body are observed at VD = 3.3 V. Mechanisms of the floating body effect (FBE) and the diode are analyzed to explain the outstanding performance. The hysteresis characteristics of BTG NMOSFETs are also presented in comparison to regular ones. Finally, the steep subthreshold characteristics of the BTG NMOSFET with floating body at low drain voltage are studied for ultralow power application.

  7. Leveling Mountains: Purpose Attenuates Links Between Perceptions of Effort and Steepness.

    PubMed

    Burrow, Anthony L; Hill, Patrick L; Sumner, Rachel

    2016-01-01

    People tend to overestimate the steepness of slopes, especially when they appraise the effort necessary to ascend them as greater. Recent studies, however, suggest the way individuals perceive visual stimuli may rely heavily on their personal motivations. In four studies (N = 517), purpose in life was tested as a motivational framework influencing how appraised effort relates to slope perception. Studies 1 and 2 found the amount of effort participants appraised necessary to ascend several virtual slopes was related to greater overestimation of their steepness. Yet, this relationship was attenuated by purpose assessed both as a disposition and experimental manipulation. Studies 3 and 4 replicated these findings using actual hills, again showing links between the amount of effort thought required to ascend them and their perceived angle were diminished by greater purpose. The discussion addresses implications of purpose as a broad motivational framework that shapes how individuals see their environment.

  8. Conversion of Impulse Voltage Generator Into Steep Wave Impulse Test-Equipment

    NASA Astrophysics Data System (ADS)

    Khan, Mohammed Zaid; Tanwar, Surender Singh; Dayama, Ravindra; Choudhary, Rahul Raj; Mangal, Ravindra

    This paper demonstrates the alternative measures to generate the Steep wave impulse by using Impulse Voltage Generator (IVG) for high voltage testing of porcelain insulators. The modification of IVG by incorporating compensation of resistor, inductor, and capacitor has been achieved and further performance of the modified system has been analyzed by applying the generated lightning impulse and analyzing the electrical characteristics of impulse waves under standard lightning and fast rise multiple lightning waveform to determine the effect to improve rise time. The advantageous results have been received and being reported such as increase in overshoot compensation, increase in capacitive and inductive load ranges. Such further reduces the duration of oscillations of standard impulse voltages. The reduction in oscillation duration of steep front impulse voltages may be utilized in up gradation of Impulse Voltage Generator System. Stray capacitance could further be added in order to get the minimized difference of measurement between simulation and the field establishment.

  9. Steep-sided domes on Venus - Characteristics, geologic setting, and eruption conditions from Magellan data

    NASA Technical Reports Server (NTRS)

    Pavri, Betina; Head, James W., III; Klose, K. B.; Wilson, Lionel

    1992-01-01

    A survey of more than 95 percent of the Venus surface reveals 145 steep-sided domes which can be subdivided into a variety of morphologic forms, the most common being shaped like inverted bowls or flat-topped domes. Results of a preliminary analysis of the distribution and geologic setting of the domes are presented. The relation of the domes to analogous terrestrial features is examined, and possible models for their mode of emplacement are outlined.

  10. Bacterial Diversity and Mycotoxin Reduction During Maize Fermentation (Steeping) for Ogi Production

    PubMed Central

    Okeke, Chiamaka A.; Ezekiel, Chibundu N.; Nwangburuka, Cyril C.; Sulyok, Michael; Ezeamagu, Cajethan O.; Adeleke, Rasheed A.; Dike, Stanley K.; Krska, Rudolf

    2015-01-01

    Bacterial diversity and community structure of two maize varieties (white and yellow) during fermentation/steeping for ogi production, and the influence of spontaneous fermentation on mycotoxin reduction in the gruel were studied. A total of 142 bacterial isolates obtained at 24–96 h intervals were preliminarily identified by conventional microbiological methods while 60 selected isolates were clustered into 39 OTUs consisting of 15 species, 10 genera, and 3 phyla by 16S rRNA sequence analysis. Lactic acid bacteria constituted about 63% of all isolated bacteria and the genus Pediococcus dominated (white maize = 84.8%; yellow maize = 74.4%). Pediococcus acidilactici and Lactobacillus paraplantarum were found at all steeping intervals of white and yellow maize, respectively, while P. claussenii was present only at the climax stage of steeping white maize. In both maize varieties, P. pentosaceus was found at 24–72 h. Mycotoxin concentrations (μg/kg) in the unsteeped grains were: white maize (aflatoxin B1 = 0.60; citrinin = 85.8; cyclopiazonic acid = 23.5; fumonisins (B1/B2/B3) = 68.4–483; zearalenone = 3.3) and yellow maize (aflatoxins (B1/B2/M1) = 22.7–513; citrinin = 16,800; cyclopiazonic acid = 247; fumonisins (B1/B2/B3) = 252–1,586; zearalenone = 205). Mycotoxins in both maize varieties were significantly (p < 0.05) reduced across steeping periods. This study reports for the first time: (a) the association of L. paraplantarum, P. acidilactici, and P. claussenii with ogi production from maize, (b) citrinin occurrence in Nigerian maize and ogi, and (c) aflatoxin M1, citrinin and cyclopiazonic acid degradation/loss due to fermentation in traditional cereal-based fermented food. PMID:26697001

  11. The Role of Prospection in Steep Temporal Reward Discounting in Gambling Addiction.

    PubMed

    Wiehler, Antonius; Bromberg, Uli; Peters, Jan

    2015-01-01

    Addiction and pathological gambling (PG) have been consistently associated with high impulsivity and a steep devaluation of delayed rewards, a process that is known as temporal discounting (TD). Recent studies indicated that enhanced episodic future thinking (EFT) results in less impulsive TD in healthy controls (HCs). In a separate line of research, it has been suggested that non-linearities in time perception might contribute to reward devaluation during inter-temporal choice. Therefore, in addition to deficits in valuation processes and executive control, impairments in EFT and non-linearities in time perception have been hypothesized to contribute to steep TD in addiction. In this study, we explore such a potential association of impairments in EFT and time perception with steep TD in PG. We investigated 20 PGs and 20 matched HCs. TD was assessed via a standard computerized binary choice task. EFT was measured using a variation of the Autobiographical Memory Interview by Levine et al. (1). Time perception was assessed with a novel task, utilizing a non-linear rating procedure via circle-size adjustments. Groups did not differ in baseline EFT. In both groups, a power law accounted time perception best, and the degree of non-linearity in time perception correlated with discounting across groups. A multiple regression analysis across all predictors and covariates revealed that only group status (PG/HC) and depression were significantly associated with discounting behavior such that PG increased TD and depression attenuated TD. Our findings speak against the idea that steep TD in PG is due to a skewed perception of time or impairments in EFT, at least under the present task conditions. The lack of overall group differences in EFT does not rule out the possibility of more complex interactions of EFT and decision-making. These interactions might be diminished in pathological gambling or addiction more generally, when other task configurations are used.

  12. Numerical errors in the presence of steep topography: analysis and alternatives

    SciTech Connect

    Lundquist, K A; Chow, F K; Lundquist, J K

    2010-04-15

    It is well known in computational fluid dynamics that grid quality affects the accuracy of numerical solutions. When assessing grid quality, properties such as aspect ratio, orthogonality of coordinate surfaces, and cell volume are considered. Mesoscale atmospheric models generally use terrain-following coordinates with large aspect ratios near the surface. As high resolution numerical simulations are increasingly used to study topographically forced flows, a high degree of non-orthogonality is introduced, especially in the vicinity of steep terrain slopes. Numerical errors associated with the use of terrainfollowing coordinates can adversely effect the accuracy of the solution in steep terrain. Inaccuracies from the coordinate transformation are present in each spatially discretized term of the Navier-Stokes equations, as well as in the conservation equations for scalars. In particular, errors in the computation of horizontal pressure gradients, diffusion, and horizontal advection terms have been noted in the presence of sloping coordinate surfaces and steep topography. In this work we study the effects of these spatial discretization errors on the flow solution for three canonical cases: scalar advection over a mountain, an atmosphere at rest over a hill, and forced advection over a hill. This study is completed using the Weather Research and Forecasting (WRF) model. Simulations with terrain-following coordinates are compared to those using a flat coordinate, where terrain is represented with the immersed boundary method. The immersed boundary method is used as a tool which allows us to eliminate the terrain-following coordinate transformation, and quantify numerical errors through a direct comparison of the two solutions. Additionally, the effects of related issues such as the steepness of terrain slope and grid aspect ratio are studied in an effort to gain an understanding of numerical domains where terrain-following coordinates can successfully be used and

  13. Fission Spectrum

    DOE R&D Accomplishments Database

    Bloch, F.; Staub, H.

    1943-08-18

    Measurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering. Decl. May 4, 1951

  14. Large sized non-uniform sediment transport at high capacity on steep slopes

    NASA Astrophysics Data System (ADS)

    Fu, X.; Zhang, L.; Duan, J. G.

    2015-12-01

    Transport of large-sized particles such as cobbles in steep streams still remains poorly understood in spite of its importance in mountain stream morphdynamics. Here we explored the law of cobble transport and the effect of cobble existence on gravel bed material transport, using flume experiments with a steep slope (4.9%) and water and sediment constantly supplying. The experiments were conducted in an 8 m long and 0.6 m wide circulating flume with the maximal size up to 90 mm and cobble concentrations in the sediment bed ranging from 22 percent to 6 percent. The sediment transport rate is on the order of 1000 g/m/s, which could be taken as high rate transport compared with existing researches. Bed load transport rate and flow variables were measured after the flume reached an equilibrium state. Bed surface topography was also measured by applying Kinect range camera before and after each run in order to analyze the fractal characteristics of the bed surface under different flow conditions. Critical shear stress of each size friction was estimated from the reference transport method (RTM) and a new hiding function was recommended. Preliminary results show that the bed was nearly in an equal mobility transport regime. We then plot dimensionless fractional transport rate versus dimensionless shear stress and assess the existing bed load transport formulas of non-uniform sediments for their applicability at high sediment transport capacity. This study contributes to the comprehension of high rate sediment transport on steep slopes.

  15. Evaluation of sediment transport in steep channels combining sediment impact sensors, tracer stones and TLS

    NASA Astrophysics Data System (ADS)

    Harb, Gabriele; Schneider, Josef; Sass, Oliver; Stangl, Johannes

    2016-04-01

    Torrential floods combined with sediment transport presents major hazards to human life and infrastructure in alpine catchments. Despite the importance of sediment transport due to the large damage caused in case of flood events, we lack data on sediment movement and sediment transport rates in steep channels and torrents to improve the understanding of sediment transport processes in this areas. This paper presents an improved application of sediment impact sensors (SIS) integrated in a unique measurement system in an Alpine catchment in Austria consisting of meteorological stations, runoff gauges and tracer stones. In addition sediment availability, mobilization and accumulation have been mapped and quantified by means of terrestrial laser scanning (TLS) and structure from motion using unmanned aerial vehicles (UAVs). Additionally a numerical model was used to simulate the bed load transport rates in the torrent. This contribution focuses on field measurements of bed load transport rates in steep channels based on SIS data, tracer stone data, bed load measurements, precipitation and discharge data. The measurement data was compared to several sediment transport formulae for steep slopes and validated with the observed deposited amount of sediment in the sediment retention basin at the outlet of the catchment.

  16. Temperature and Time of Steeping Affect the Antioxidant Properties of White, Green, and Black Tea Infusions.

    PubMed

    Hajiaghaalipour, Fatemeh; Sanusi, Junedah; Kanthimathi, M S

    2016-01-01

    Tea (Camellia sinensis) is the most highly consumed beverage in the world next to water. The common way of preparation is steeping in hot water which is varying for different type of tea. We investigated the antioxidant properties of 6 type of tea leaves under different time and temperatures of extraction method used. In general, all samples tested in this study demonstrated high levels of antioxidant capacity and antioxidant activity. The results indicate that the antioxidants activity is significantly affected by time and temperature of steeping and the highest was depending on the variety. White state values, green and black teas showed different levels of antioxidants under different extraction conditions. Overall, the highest activity for white tea was in prolonged hot and in some assays prolonged hot and cold extracts, whereas for green tea the highest activity observed in prolonged cold steeping while, for black tea was in short hot water infusion. The results of this study showed the antioxidant capacity of white and green tea was greater than black tea.

  17. Experimental investigation of steep-front short duration (SFSD) surge effects on power systems components

    SciTech Connect

    Miller, D.B. . Dept. of Electrical and Computer Engineering)

    1992-05-01

    Results are reported from experiments in which steep-front, short- duration (SFSD) voltage impulses were imposed on various electrical distribution components. These pulses were generated by switching a section of charged, high voltage coaxial cable across the component under study. Components included underground distribution cable, terminators, insulators and arresters. SFSD voltage needed to flashover 15 kV polyethylene cable with a single pulse is approximately 625 kV peak. Strength of polyethylene cable decreases with increasing number of SFSD pulses, indicating cumulative degradation of the polymer. For 15 kV and 25 kV cable terminators, the SFSD CFO was over twice the rated standard lightning BIL for the same units. Similarly, porcelain suspension insulators required more than a doubling of voltage to decrease time to flashover from 1 microsecond to .1 microsecond. Arresters were found to respond rapidly to steep-front current pulses, but the arrester material itself was found to result in a higher discharge voltage for SFSD pulses. Arresters also showed a delay in turn-on of current following the arrival of a steep-front voltage surge.

  18. Process analysis, quantification and modelling of erosion on steep unvegetated hillslopes:

    NASA Astrophysics Data System (ADS)

    Neugirg, Fabian; Kaiser, Andreas; Schindewolf, Marcus; Schmidt, Jürgen; Becht, Michael; Haas, Florian

    2016-04-01

    Soil erosion is a problem in many parts of the world. While in agricultural environments the geomorphological drivers of soil erosion are well known, the process understanding in steep alpine environments is still lacking. Steep hillslopes in different climatic settings distributed in Germany and Italy were monitored for at least three years in order to gain better knowledge in the evolution of the unvegetated slopes. The monitoring setup was mainly based on terrestrial laserscanning (TLS) and was expanded with other monitoring methods, like aerial- and terrestrial-based structure from motion, aerial images and airborne laser scanning data. TLS data were mainly used to analyse processes on plot or hillslope scale. In order to regionalize these values, we used two different modelling approaches: a rule-based statistical and the physical-based model Erosion 3D. The latter one had to be adopted from flat agricaltural areas to steep slopes. Parameters for modeling purposes were acquired by field work. Therefore an established rainfall simulator was customized for the application in alpine terrain. The results showed clear differences in the seasonal behaviour of the acting geomorphological processes in nearly all study areas. Furthermore a quantification was possible for each process involved in hillslope development. Additionally, both models showed that an adaptation to the hillslopes was possible and provided satisfying results in all research areas. This presentation aims at summarizing the findings and key results of the three year study period.

  19. Evidence of Spin and Energy Extraction in a Galactic Black Hole Candidate: The XMM-NEWTON/EPIC SPECTRUM of XTE 11650-500

    NASA Technical Reports Server (NTRS)

    Miller, J. M.; Fabian, A. C.; Wunands, R.; Reynolds, C. S.; Ehle, M.; Freyberg, M. J.; VanDerKlis, M.; Lewin, W. H. G.; Sanchez-Fernandez, C.; Castro-Tirado, A. J.

    2002-01-01

    We observed the Galactic black hole candidate XTE J1650-500 early in its fall of 2001 outburst with the XMM-Newton European Photon Imaging pn Camera (EPIC-pn). The observed spectrum is consistent with the source having been in the very high state. We h d a broad, skewed Fe Kar emission line that suggests the primary in this system may be a Kerr black hole and that indicates a steep disk emissivity profile that is hard to explain in terms of a standard accretion disk model. These results are quantitatively and qualitatively similar to those from an XMM-Newton observation of the Seyfert galaxy MCG -6-30-15. The steep emissivity in MCG -6-30-15 may be explained by the extraction and dissipation of rotational energy from a black hole with nearly maximal angular momentum or from material in the plunging region via magnetic connections to the inner accretion disk. If this process is at work in both sources, an exotic but fundamental general relativistic prediction may be confirmed across a factor of l0(exp 6) in black hole mass. We discuss these results in terms of the accretion flow geometry in stellar-mass black holes and the variety of enigmatic phenomena often observed in the very high state.

  20. 0108 + 388 - A compact double source with surprising properties

    NASA Technical Reports Server (NTRS)

    Baum, S. A.; O'Dea, C. P.; De Bruyn, A. G.; Murphy, D. W.

    1990-01-01

    49 cm, 6 cm, and 20 cm observations of the compact double ratio source 0108 + 388 are presented. Extended emission about 20 deg to the east of the core is detected which resembles a hot spot/lobe with a bridge of emission extending back to the core. This is the first detection of extended emission associated with such a source, and it is inconsistent with the suggestion that such sources are very young classical double radio sources. The inconsistency can be reconciled if the activity in this object is recurrent and the emission is the relic of a previous epoch of activity. Alternatively, the source may be a normal-aged radio galaxy in which most of the radio-emitting plasma is currently unable to escape the nuclear regions of the galaxy. The steep low-frequency spectrum of the core is probably related to the origin of the compact double and suggests that both components are very sharply confined on both their inner and outer edges.

  1. Bedform migration in steep channels: from local avalanches to large scale changes

    NASA Astrophysics Data System (ADS)

    Mettra, F.; Heyman, J.; Ancey, C.

    2013-12-01

    Many studies have emphasized the strength of bedload transport fluctuations in steep streams, especially at low and intermediate transport conditions (relative to the threshold of incipient motion). The origins of these fluctuations, which appear on a wide range of time scales, are still not well understood. In this study, we present the data obtained from a 2D idealized laboratory experiment with the objective of simultaneously recording the channel bed evolution and bedload transport rate at a high temporal resolution. A 3-m long by 8-cm wide transparent flume filled with well-sorted natural gravel (d50=6.5 mm) was used. An efficient technique using accelerometers has been developed to record the arrival time of every particle at the outlet of the flume for long experimental durations (up to a few days). In addition, bed elevation was monitored using cameras filming from the side of the channel, allowing the observation of global aggradation/degradation as well as bedform migration. The experimental parameters were the water discharge, the flume inclination (from 2° to 5°) and the constant feeding rate of sediments. Large-scale bed evolution showed successive aggradation and rapid degradation periods. Indeed, the measured global channel slope, i.e. mean slope over the flume length, fluctuated continuously within a range sometimes wider than 1° (experimental parameters were constant over the entire run). The analysis of these fluctuations provides evidence that steep channels behave like metastable systems, similarly to grain piles. The metastable effects increased for steeper channels and lower transport conditions. In this measurement campaign, we mainly observed upstream-migrating antidunes. For each run, various antidune heights and celerities were measured. On average, the mean antidune migration rate increased with decreasing channel slope and increasing sediment feeding rate. Relatively rare tall and fast-moving antidunes appeared more frequently at high

  2. Thermal stability effects on the separated flow over a steep 2-D hill

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Porte-Agel, F.

    2012-12-01

    Transport of momentum and scalars in turbulent boundary-layer flows over complex topography has been of great interest in the atmospheric sciences and wind engineering communities. Applications include but are not limited to weather forecasting, air pollution dispersion, aviation safety control, and wind energy project planning. Linear models have been well accepted to predict boundary-layer flows over topography with gentle slope. However, once the slope of the topography is sufficientlyo steep that flow separation occurs, linear models are not applicable. Modeling the turbulent transport of momentum and scalars in such flows has to be achieved through non-linear models, such as Reynolds-averaged Navier-Stokes solvers and large-eddy simulations (LES). Dynamics of the separated boundary-layer flows over steep topography is affected by the shape and size of the topography, surface characteristics (e.g., roughness and temperature) and atmospheric thermal stability. Most wind-tunnel experiments of boundary-layer flows over idealized topography (e.g. 2-D or 3-D hills, axisymmetric bumps) do not take thermal stability effects into account due to difficulty of physical simulation. We conducted comprehensive experimental investigation of stably- and unstably- stratified boundary layers over a steep 2-D hill in the thermally-controlled boundary-layer wind tunnel at the Saint Anthony Falls Laboratory. The 2-D model hill has a steepest slope of 0.73 and its shape follows a cosine square function: h=Hcos^2 (πx/L) for -L/2 ≤ x ≤ L/2 , where the maximum height H is 7 cm and the total width L is 15 cm. High-resolution Particle Image Velocimetry (PIV) provides dynamic information of the separated shear layer, the recirculation zone and flow reattachment. Turbulent momentum and scalar (heat) fluxes were characterized up to the top of the thermal boundary layer using a triple-wire (cross-wire and cold-wire) anemometer. Results indicate that promoted and suppressed turbulence

  3. Milli-Arcsecond Morphology and Structural Changes in a Complete Sample of Radio Sources

    NASA Astrophysics Data System (ADS)

    Pearson, T. J.; Readhead, A. C. S.; Barthel, P. D.; Conway, J. E.; Myers, S. T.

    1993-05-01

    We have conducted a VLBI survey of a complete, flux-density--limited sample of 65 extragalactic radio sources, selected at 5 GHz, in order to study their morphology and to look for superluminal motion and other structural changes. First-epoch images of 37 sources were published by Pearson & Readhead (1988, ApJ, 328, 114). Here we present 5-GHz images, with a resolution ~ 1 milliarcsec, taken at three epochs spread over 9 years for each of 25 sources. The majority of the sources have an asymmetric, core-jet morphology. Several of these are superluminal sources in which an emission feature moves outward along the jet at v_app > c (e.g., 0850+581, 1642+690, 1928+738, BL Lac, 3C 216, 3C 345). Several other sources with similar morphology, however, show no changes in relative positions of subcomponents, although subcomponent flux densities do change (e.g., 0711+356, 1652+398, 1823+568). We draw attention to a new class of ``compact symmetric'' objects with double or triple morphology (e.g., 0108+388, 0710+439, 2352+495). We have placed limits < c on relative motion of components in these sources, and they show little if any evidence for relativistic beaming. The central engine appears to lie midway between two lobes ~ 100 pc apart. The sample also includes some compact steep-spectrum sources and other sources that are difficult to classify.

  4. Ethanol production from syngas by Clostridium strain P11 using corn steep liquor as a nutrient replacement to yeast extract.

    PubMed

    Maddipati, Prasanth; Atiyeh, Hasan K; Bellmer, Danielle D; Huhnke, Raymond L

    2011-06-01

    The feasibility of replacing yeast extract (YE) by corn steep liquor (CSL), a low cost nutrient source, for syngas fermentation to produce ethanol using Clostridium strain P11 was investigated. About 32% more ethanol (1.7 g L(-1)) was produced with 20 g L(-1) CSL media in 250-mL bottle fermentations compared to media with 1 g L(-1) YE after 360 h. Maximum ethanol concentrations after 360 h of fermentation in a 7.5-L fermentor with 10 and 20 g L(-1) CSL media were 8.6 and 9.6 g L(-1), respectively, which represent 57% and 60% of the theoretical ethanol yields from CO. Only about 6.1 g L(-1) of ethanol was obtained in the medium with 1 g L(-1) YE after 360 h, which represents 53% of the theoretical ethanol yield from CO. The use of CSL also enhanced butanol production by sevenfold compared to YE in bottle fermentations. These results demonstrate that CSL can replace YE as the primary medium component and significantly enhance ethanol production by Clostridium strain P11.

  5. High-cell-density fed-batch culture of Saccharomyces cerevisiae KV-25 using molasses and corn steep liquor.

    PubMed

    Vu, Van Hanh; Kim, Keun

    2009-12-01

    High-cell-density cultivation of yeast was investigated using the agricultural waste products corn steep liquor (CSL) and molasses. The Saccharomyces cerevisiae KV-25 cell mass was significantly dependent on the ratio between C and N sources. The concentrations of molasses and CSL in the culture medium were statistically optimized at 10.25% (v/v) and 16.87% (v/v), respectively, by response surface methodology (RSM). Batch culture in a 5-l stirred tank reactor using the optimized medium resulted in a cell mass production of 36.5 g/l. In the fed-batch culture, the feed phase was preceded by a batch phase using the optimized medium, and a very high dried-cell-mass yield of 187.63 g/l was successfully attained by feeding a mixture of 20% (v/v) molasses and 80% (v/v) CSL at a rate of 22 ml/h. In this system, the production of cell mass depended mainly on the agitation speed, the composition of the feed medium, and the glucose level in the medium, but only slightly on the aeration rate.

  6. Time-series analysis on bed morphology affected by debris flows along a headwater steep channel in Ohya-kuzure landslide, central Japan

    NASA Astrophysics Data System (ADS)

    Hayakawa, Y. S.; Imaizumi, F.; Hotta, N.; Tsunetaka, H.

    2013-12-01

    Deformation of steep terrain has been occurring since the formation of Ohyakuzure landslide in 1707. Although erosion controls in recent decades have resulted in vegetation recovery in downstream portions of the landslide terrain, hillslope erosion and debris flows frequently occur in uppermost steep subwatersheds in the landslide area to yield vast amount of sediment downstream. Ichino-sawa subwatershed in the landslide terrain, where detailed monitoring of debris flows and related topographic changes have previously been performed, has particularly steep slopes, and geomorphic processes therein have been quite active. Freeze-thaw weathering of fractured bedrock on hillslopes made of shale and sandstone frequently occurs in winter to spring season, and resultant sediment particles are provided into channel beds, which act as a source of debris flows that frequently occurs in summer season with heavy or accumulated rainfalls. High-resolution assessment of erosion/deposition patterns in channel bed of the Ichinosawa catchment was performed using multi-temporal terrestrial laser scanning data covering 3 seasons for 2 years. Seasonal changes in spatial distribution of erosion and deposition in the channel bed is quantified using a 0.1-m DEM converted from the original point cloud by TLS. The multi-temporal datasets provides an estimate of annual sediment storage and yield on the order of 1,000 - 5,000 m3. Analysis of changes in elevation by transverse and longitudinal profiles shows contrasting patterns of erosion and deposition along the studied reach: in particular, changes in bed elevation is found to be less in a 50-m long reach, whose downstream part seems bounded by valley narrowing and a knickpoint. Several topographic metrics, including stream gradient, surface roughness and topographic openness, were examined to estimate the characteristics of differing transport processes induced by debris flows along the reaches.

  7. Enhanced stability of steep channel beds to mass failure and debris flow initiation

    NASA Astrophysics Data System (ADS)

    Prancevic, J.; Lamb, M. P.; Ayoub, F.; Venditti, J. G.

    2015-12-01

    Debris flows dominate bedrock erosion and sediment transport in very steep mountain channels, and are often initiated from failure of channel-bed alluvium during storms. While several theoretical models exist to predict mass failures, few have been tested because observations of in-channel bed failures are extremely limited. To fill this gap in our understanding, we performed laboratory flume experiments to identify the conditions necessary to initiate bed failures in non-cohesive sediment of different sizes (D = 0.7 mm to 15 mm) on steep channel-bed slopes (S = 0.45 to 0.93) and in the presence of water flow. In beds composed of sand, failures occurred under sub-saturated conditions on steep bed slopes (S > 0.5) and under super-saturated conditions at lower slopes. In beds of gravel, however, failures occurred only under super-saturated conditions at all tested slopes, even those approaching the dry angle of repose. Consistent with theoretical models, mass failures under super-saturated conditions initiated along a failure plane approximately one grain-diameter below the bed surface, whereas the failure plane was located near the base of the bed under sub-saturated conditions. However, all experimental beds were more stable than predicted by 1-D infinite-slope stability models. In partially saturated sand, enhanced stability appears to result from suction stress. Enhanced stability in gravel may result from turbulent energy losses in pores or increased granular friction for failures that are shallow with respect to grain size. These grain-size dependent effects are not currently included in stability models for non-cohesive sediment, and they may help to explain better the timing and location of debris flow occurrence.

  8. Distributed snow and rock temperature modelling in steep rock walls using Alpine3D

    NASA Astrophysics Data System (ADS)

    Haberkorn, Anna; Wever, Nander; Hoelzle, Martin; Phillips, Marcia; Kenner, Robert; Bavay, Mathias; Lehning, Michael

    2017-02-01

    In this study we modelled the influence of the spatially and temporally heterogeneous snow cover on the surface energy balance and thus on rock temperatures in two rugged, steep rock walls on the Gemsstock ridge in the central Swiss Alps. The heterogeneous snow depth distribution in the rock walls was introduced to the distributed, process-based energy balance model Alpine3D with a precipitation scaling method based on snow depth data measured by terrestrial laser scanning. The influence of the snow cover on rock temperatures was investigated by comparing a snow-covered model scenario (precipitation input provided by precipitation scaling) with a snow-free (zero precipitation input) one. Model uncertainties are discussed and evaluated at both the point and spatial scales against 22 near-surface rock temperature measurements and high-resolution snow depth data from winter terrestrial laser scans.In the rough rock walls, the heterogeneously distributed snow cover was moderately well reproduced by Alpine3D with mean absolute errors ranging between 0.31 and 0.81 m. However, snow cover duration was reproduced well and, consequently, near-surface rock temperatures were modelled convincingly. Uncertainties in rock temperature modelling were found to be around 1.6 °C. Errors in snow cover modelling and hence in rock temperature simulations are explained by inadequate snow settlement due to linear precipitation scaling, missing lateral heat fluxes in the rock, and by errors caused by interpolation of shortwave radiation, wind and air temperature into the rock walls.Mean annual near-surface rock temperature increases were both measured and modelled in the steep rock walls as a consequence of a thick, long-lasting snow cover. Rock temperatures were 1.3-2.5 °C higher in the shaded and sunny rock walls, while comparing snow-covered to snow-free simulations. This helps to assess the potential error made in ground temperature modelling when neglecting snow in steep bedrock.

  9. Origin of steep-pointed and flat-topped volcanic cones in Southwest volcanic field

    NASA Astrophysics Data System (ADS)

    Fukui, U.; Hirota, F.; Yokose, H.

    2002-12-01

    KR01-12 cruise of Japan Marine Science and Technology Center using ROV KAIKO and its mother ship R/V KAIREI were carried out around Hawaii islands in the early fall of 2001. During this cruise, two dives of ROV KAIKO were made on southwest Oahu volcanic field (K203 and K206).The new Seabeam bathymetry revealed that there are remarkable topographic features: flat-topped volcanic cone, ca.2.5 in diameter and 200m in height; steep pointed cone, ellipsoidal in plain: major axis 2km, minor axis 0.5km; 200-400 m in height. This volcanic topographies are similar to those described in elsewhere e.g., Clague et al., 2001. Flat-topped cones distributed in this area are different from other area in their occurrence. They are accompanied with steep-pointed cone. In order to study the geological and petrological relationship between flat-topped cone and steep-pointed cone, both K203 and K206 have been analyzed by video image, thin sections and bulk rock chemistry. The rocks recovered from K206 and K203 are trachybasalt and basanite respectibly. There is no critical differences between FTVC and SPVCin their bulk chemistry. For example rocks from FTCV are almost identical to the SPCV in SiO2 contents in the same site. Total AK concentration of rocks from FTCV is lower than those of SPVC in K203, but FTVC is higher than SPCV in K206. This result implies that topographical characters are not correlated with bulk chemistry. Both in K206 or K203, rocks collected from SPVC have higher vesicularity, ranging from 20 to 40%, and higher crystallinity in groundmass than those from FTCV. It is suggest that differences in topographical characteristics between FTVC and SPVC are controlled by physical property of the groundmass. That is, the viscosity of magma lead to rise due to exsolution of gas phase from melt.

  10. An exact solution for ideal dam-break floods on steep slopes

    USGS Publications Warehouse

    Ancey, C.; Iverson, R.M.; Rentschler, M.; Denlinger, R.P.

    2008-01-01

    The shallow-water equations are used to model the flow resulting from the sudden release of a finite volume of frictionless, incompressible fluid down a uniform slope of arbitrary inclination. The hodograph transformation and Riemann's method make it possible to transform the governing equations into a linear system and then deduce an exact analytical solution expressed in terms of readily evaluated integrals. Although the solution treats an idealized case never strictly realized in nature, it is uniquely well-suited for testing the robustness and accuracy of numerical models used to model shallow-water flows on steep slopes. Copyright 2008 by the American Geophysical Union.

  11. Steep Satellite Altimetry Gradients as a Proxy to the Edge of the Continental Crust

    NASA Astrophysics Data System (ADS)

    Lawver, L. A.; Gahagan, L. M.

    2005-05-01

    Tight-fit plate reconstructions are produced using a global database constrained by marine magnetic anomalies tied to a consistent timescale, paleomagnetic poles, seafloor age dates based on drilling results, and fracture zone and transform fault lineations picked from ship-track and satellite altimetry data. Where a prominent steep gradient in the satellite altimetry data is present near the continental-ocean transition, it is used as a proxy to the continental shelf break [CSB]. Continental block outlines are based on digitization of the steep gradient. In some places, notably off Namibia, there is a very close correlation between that gradient and the ocean-continent boundary deduced from seismic refraction and reflection data. In other regions, there may be some stretched continental crust oceanward of the steep gradient but for reconstruction purposes we assume the crust to be predominantly continental landward of the boundary and oceanic, seaward of the line. Good matchs for conjugate CSBs are found in many places world-wide along passive margins and these will be highlighted. Particularly good matches are observed between the cratonic edges of East Antarctica as determined by sub-ice topographic highs seen along the margins of East Antarctica with respect to Madagascar, Sri Lanka, the southern half of the eastern margin of India, and the region of Australia between 124° E and 133° E along the Great Australian Bight (GAB). There are overlaps of the reconstructed conjugate CSBs, with one overlap between India and East Antarctica (70° E to 85° E) and one between East Antarctica and the western section of the GAB (105° E to 120° E). These two overlaps are coincident with the outer margins of the Lambert Graben - Prydz Bay Basin and the Aurora Subglacial Basin, respectively. It is known that there are substantial glacially-derived sediments prograded off the continental margin onto oceanic crust at Prydz Bay where there may be as much as 200 km in width of

  12. Low-Power RIE of SiO2 in CHF3 To Obtain Steep Sidewalls

    NASA Technical Reports Server (NTRS)

    Turner, Tasha; Wu, Chi

    2003-01-01

    A reactive-ion etching (RIE) process has been developed to enable the formation of holes with steep sidewalls in a layer of silicon dioxide that covers a silicon substrate. The holes in question are through the thickness of the SiO2 and are used to define silicon substrate areas to be etched or to be built upon through epitaxial deposition of silicon. The sidewalls of these holes are required to be vertical in order to ensure that the sidewalls of the holes to be etched in the substrate or the sidewalls of the epitaxial deposits, respectively, also turn out to be vertical.

  13. Dynamic changes in phenolic compounds and antioxidant activity in oats (Avena nuda L.) during steeping and germination.

    PubMed

    Xu, Jian Guo; Tian, Cheng Rui; Hu, Qing Ping; Luo, Ji Yang; Wang, Xiang Dong; Tian, Xiang Dong

    2009-11-11

    Samples from naked oat were steeped and germinated under controlled conditions in an incubator. Changes of phenolic compounds and antioxidant activity were investigated in oats during steeping and germination. Results revealed that phenolic compounds and antioxidant activity of oats varied with the difference in steeping and germination stages. Compared with raw grains, short-term steeping treatment did not show significant effects (p > 0.05) on phenolic content. Germination can significantly result in the decrease in bound phenolic and the increase in free and total phenolics. Main phenolic acids and avenanthramides were isolated and quantified by HPLC analysis. During steeping, phenolic acids decreased (p < 0.05); avenanthramide N-(3',4'-dihydroxy)-(E)-cinnamoyl-5-hydroxyanthranilic acid first decreased and then increased (p < 0.05), while avenanthramides N-(4'-hydroxy)-(E)-cinnamoyl-5-hydroxyanthranilic acid and N-(4'-hydroxy-3'-methoxy)-(E)-cinnamoyl-5-hydroxyanthranilic acid did not change significantly (p > 0.05). During germination, gallic and caffeic acids first increased (p < 0.05) and then decreased, whereas p-coumaric and ferulic acids and avenanthramides increased (p < 0.05). Nevertheless, avenanthramides did not change significantly (p > 0.05) during the last stage of germination. Oat extracts exhibited increasing high antioxidant activity with the steeping and germination going on, which may explain that antioxidant activity correlated (p < 0.01) significantly with the content of phenolic compounds.

  14. Optimization of a corn steep medium for production of ethanol from synthesis gas fermentation by Clostridium ragsdalei.

    PubMed

    Saxena, Jyotisna; Tanner, Ralph S

    2012-04-01

    Fermentation of biomass derived synthesis gas to ethanol is a sustainable approach that can provide more usable energy and environmental benefits than food-based biofuels. The effects of various medium components on ethanol production by Clostridium ragsdalei utilizing syngas components (CO:CO(2)) were investigated, and corn steep liquor (CSL) was used as an inexpensive nutrient source for ethanol production by C. ragsdalei. Elimination of Mg(2+), NH(4) (+) and PO(4) (3-) decreased ethanol production from 38 to 3.7, 23 and 5.93 mM, respectively. Eliminating Na(+), Ca(2+), and K(+) or increasing Ca(2+), Mg(2+), K(+), NH(4) (+) and PO(4) (3-) concentrations had no effect on ethanol production. However, increased Na(+) concentration (171 mM) inhibited growth and ethanol production. Yeast extract (0.5 g l(-1)) and trace metals were necessary for growth of C. ragsdalei. CSL alone did not support growth and ethanol production. Nutrients limiting in CSL were trace metals, NH(4) (+) and reducing agent (Cys: cysteine sulfide). Supplementation of trace metals, NH(4) (+) and CyS to CSL (20 g l(-1), wet weight basis) yielded better growth and similar ethanol production as compared to control medium. Using 10 g l(-1), the nutritional limitation led to reduced ethanol production. Higher concentrations of CSL (50 and 100 g l(-1)) were inhibitory for cell growth and ethanol production. The CSL could replace yeast extract, vitamins and minerals (excluding NH(4) (+)). The optimized CSL medium produced 120 and 50 mM of ethanol and acetate, respectively. The CSL could provide as an inexpensive source of most of the nutrients required for the syngas fermentation, and thus could improve the economics of ethanol production from biomass derived synthesis gas by C. ragsdalei.

  15. A Measurement of the Millimeter Emission and the Sunyaev-zel'dovich Effect Associated with Low-frequency Radio Sources

    NASA Technical Reports Server (NTRS)

    Gralla, Megan B.; Crichton, Devin; Marriage, Tobias A.; Mo, Wenli; Aguirre, Paula; Addison, Graeme E.; Asboth, V.; Battaglia, Nick; Bock, James; Bond, J. Richard; Devlin, Mark J.; Duenner, Rolando; Hajian, Amir; Halpern, Mark; Hilton, Matt; Hincks, Adam D.; Hlozek Renee A.; Huffenberger, Kevin M.; Hughes, John P.; Ivison, R. J.; Kosowsky, Arthur; Lin, Yen-Ting; Switzer, Eric R.; Wollack, Edward J.; Zemcov, Michael B.

    2013-01-01

    We present a statistical analysis of the millimeter-wavelength properties of 1.4 GHz-selected sources and a detection of the Sunyaev-Zel'dovich Effect associated with the halos that host them. The Atacama Cosmology Telescope (ACT) has conducted a survey at 148 GHz, 218 GHz and 277 GHz along the celestial equator. Using samples of radio sources selected at 1.4 GHz from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) Survey and the National Radio Astronomy Observatory Very Large Array Sky Survey (NVSS), we measure the stacked 148, 218 and 277 GHz flux densities for sources with 1.4 GHz flux densities ranging from 5 to 200 mJy. At these flux densities, the radio source population is dominated by active galactic nuclei (AGN), with both steep and at spectrum populations, which have combined radio-to-millimeter spectral indices ranging from 0.5 to 0.95, reecting the prevalence of steep spectrum sources at high flux densities and the presence of at spectrum sources at lower flux densities. The thermal Sunyaev-Zelapos;dovich (SZ) eect associated with the halos that host the AGN is detected at the 5 level through its spectral signature. When we compare the SZ eect with weak lensing measurements of radio galaxies, we find that the relation between the two is consistent with that measured by Planck for local bright galaxies. We present a detection of the SZ eect in some of the lowest mass halos (average M(sub 200) approx. equals 10(exp 13) solar M h(sup-1) (sub 70) ) studied to date. This detection is particularly important in the context of galaxy evolution models, as it confirms that galaxies with radio AGN also typically support hot gaseous halos. With Herschel* observations, we show that the SZ detection is not significantly contaminated by dusty galaxies or by dust associated with the AGN or galaxies hosting the AGN. We show that 5 mJy < S(sub 1:4) < 200 mJy radio sources contribute l(l +1)C(sub l)/(2 pi ) = 0:37+/- 0:03 micro K(exp 2) to the angular

  16. Stability of Steep Gravity--Capillary Solitary Waves in Deep Water

    NASA Astrophysics Data System (ADS)

    Akylas, T. R.; Calvo, D. C.

    2000-11-01

    The stability of steep gravity--capillary solitary waves in deep water is numerically investigated using the full nonlinear water-wave equations with surface tension. As was found in prior work based on model equations for small-amplitude solitary waves in shallow water, out of the two solution branches that bifurcate at the minimum gravity--capillary phase speed, solitary waves of depression again turn out to be stable while those of elevation are unstable to small disturbances. Motivated by the experiments of Longuet-Higgins & Zhang (Phys. Fluids 9:1963--1968, 1997), we also consider the forced problem of a localised pressure distribution applied to the free surface of a stream with speed below the minimum gravity--capillary phase speed. We find that the finite-amplitude forced solitary-wave solution branch computed by Vanden-Broeck & Dias (J. Fluid Mech. 240:549--557, 1992) is unstable but the branch corresponding to Rayleigh's linearised solution is stable. The significance of viscous effects is assessed; the effects of instability in steep waves generally are comparable to, and in some cases greater than, those of dissipation. These findings are discussed in connection with the experimental observations of Longuet-Higgins & Zhang.

  17. Rehabilitation and flood management planning in a steep, boulder-bedded stream.

    PubMed

    Caruso, Brian S; Downs, Peter W

    2007-08-01

    This study demonstrates the integration of rehabilitation and flood management planning in a steep, boulder-bedded stream in a coastal urban catchment on the South Island of New Zealand. The Water of Leith, the primary stream flowing through the city of Dunedin, is used as a case study. The catchment is steep, with a short time of concentration and rapid hydrologic response, and the lower stream reaches are highly channelized with floodplain encroachment, a high potential for debris flows, significant flood risks, and severely degraded aquatic habitat. Because the objectives for rehabilitation and flood management in urban catchments are often conflicting, a number of types of analyses at both the catchment and the reach scales and careful planning with stakeholder consultation were needed for successful rehabilitation efforts. This included modeling and analysis of catchment hydrology, fluvial geomorphologic assessment, analysis of water quality and aquatic ecology, hydraulic modeling and flood risk evaluation, detailed feasibility studies, and preliminary design to optimize multiple rehabilitation and flood management objectives. The study showed that all of these analyses were needed for integrated rehabilitation and flood management and that some incremental improvements in stream ecological health, aesthetics, and public recreational opportunities could be achieved in this challenging environment. These methods should be considered in a range of types of stream rehabilitation projects.

  18. Flat-top steep-edge response of photodetetors by circuit control method

    NASA Astrophysics Data System (ADS)

    Wang, Li; Huang, Yongqing; Duan, Xiaofeng; Yan, Qiang; Ren, Xiaomin; Huang, Hui; Wang, Qi; Zhang, Xia

    2010-10-01

    This paper proposes a circuit control method achieving the flat-top steep-edge response of photodetectors. The response is realized using three wavelength selective photodetectors and the circuit which consists of amplifiers, comparators and a AND gate. Two groups of experiments were carried out. In group 1, 0.5dB, 3dB, 20dB bandwidths are 2.76nm, 3.29nm, 4.58nm from 1546nm to 1549.3nm. In group 2, 0.5dB, 3dB, 20dB bandwidths are 3.19nm, 2.89nm, 3.06nm from 1554.8nm to 1557.6nm. The results of experiments show that the desirable flat-top steep-edge response can be gained and the response linewidth is adjustable by selecting different photodetectors, so that the requirement of the WDM system and the network can be met. The method is easy to realize with low cost and has wide application in optical measurements and optical processing etc.

  19. Rehabilitation and Flood Management Planning in a Steep, Boulder-Bedded Stream

    NASA Astrophysics Data System (ADS)

    Caruso, Brian S.; Downs, Peter W.

    2007-08-01

    This study demonstrates the integration of rehabilitation and flood management planning in a steep, boulder-bedded stream in a coastal urban catchment on the South Island of New Zealand. The Water of Leith, the primary stream flowing through the city of Dunedin, is used as a case study. The catchment is steep, with a short time of concentration and rapid hydrologic response, and the lower stream reaches are highly channelized with floodplain encroachment, a high potential for debris flows, significant flood risks, and severely degraded aquatic habitat. Because the objectives for rehabilitation and flood management in urban catchments are often conflicting, a number of types of analyses at both the catchment and the reach scales and careful planning with stakeholder consultation were needed for successful rehabilitation efforts. This included modeling and analysis of catchment hydrology, fluvial geomorphologic assessment, analysis of water quality and aquatic ecology, hydraulic modeling and flood risk evaluation, detailed feasibility studies, and preliminary design to optimize multiple rehabilitation and flood management objectives. The study showed that all of these analyses were needed for integrated rehabilitation and flood management and that some incremental improvements in stream ecological health, aesthetics, and public recreational opportunities could be achieved in this challenging environment. These methods should be considered in a range of types of stream rehabilitation projects.

  20. Modelling Steep Surfaces by Various Configurations of Nadir and Oblique Photogrammetry

    NASA Astrophysics Data System (ADS)

    Casella, V.; Franzini, M.

    2016-06-01

    Among the parts of the territory requiring periodical and careful monitoring, many have steep surfaces: quarries, river basins, land-slides, dangerous mountainsides. Aerial photogrammetry based on lightweight unmanned aircraft systems (UAS) is rapidly becoming the tool of election to survey limited areas of land with a high level of detail. Aerial photogrammetry is traditionally based on vertical images and only recently the use of significantly inclined imagery has been considered. Oblique photogrammetry presents peculiar aspects and offers improved capabilities for steep surface reconstruction. Full comprehension of oblique photogrammetry still requires research efforts and the evaluation of diverse case studies. In the present paper, the focus is on the photogrammetric UAS-based survey of a part of a large sandpit. Various flight configurations are considered: ordinary linear strips, radial strips (as the scarp considered has a semi-circular shape) and curved ones; moreover, nadir looking and oblique image blocks were acquired. Around 300 control points were measured with a topographic total station. The various datasets considered are evaluated in terms of density of the extracted point cloud and in terms of the distance between the reconstructed surface and a number of check points.

  1. Polyphenolic Profile and Antioxidant Activities of Oolong Tea Infusion under Various Steeping Conditions

    PubMed Central

    Su, Xinguo; Duan, Jun; Jiang, Yueming; Duan, Xuewu; Chen, Feng

    2007-01-01

    The phenolic profile and antioxidant activities of oolong tea extract were investigated after tea was steeped in 90 or 100 °C water for 3 or 10 min. The extraction yield increased with increasing temperature and extended steeping time. However, higher temperature and longer time (100 °C water for 10 min) led to loss of phenolics. The aqueous extract of oolong tea (AEOT) at 100 °C for 3 min exhibited the strongest antioxidant activity. The major polyphenolic components of the AEOT were identified as (−)-epigallocatechin (EGC), (−)-epigallocatechin gallate (EGCG) and (−)-epicatechin-3-gallate (ECG). The two major catechins (EGC and EGCG) in the tea infusion contributed significantly to the investigated antioxidant activities [i.e., the 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical scavenging and superoxide radical scavenging activities] with high correlation values in r = 0.9486 and 0.9327 for the EGC and r = 0.9592 and 0.8718 for the EGCG, respectively.

  2. Low-flow hydraulic geometry of small, steep mountain streams in southwest British Columbia

    NASA Astrophysics Data System (ADS)

    Reid, Donald E.; Hickin, Edward J.; Babakaiff, Scott C.

    2010-10-01

    This investigation explores the at-a-station hydraulic geometry (AHG) of small, steep mountain streams at low discharge. Thirteen reaches in five tributaries of Chilliwack River, British Columbia, ranging in size from 12 to 77 km 2 are examined. The resulting data set is composed of eight to twelve measurements of water-surface width, mean depth, and mean velocity at each of 61 cross sections or 625 unique combinations of the three variables. Mean velocity in a given cross section responds most rapidly to changing discharge, and 31 of the 61 cross sections have velocity exponents that are greater than the water-surface width and mean-depth exponents combined. The velocity exponent ( m) averages 0.51, while the mean water-surface width exponent ( b) and mean-depth exponent ( f) average 0.20 and 0.29, respectively. Somewhat surprisingly, the AHG of steep mountain streams can be reasonably predicted from just a few measurements of the primary flow variables and stream discharge. While conditions at the cross section appear predictable from a few measurements, extrapolating the results from one cross section to another in the same reach involves large errors. The section-to-section variability of the exponents and coefficients, even when they are located in similar channel units such as riffles, prevents accurate extrapolation to unmeasured cross sections.

  3. Transforming gate misalignment into a unique opportunity to facilitate steep switching in junctionless nanotransistors

    NASA Astrophysics Data System (ADS)

    Gupta, Manish; Kranti, Abhinav

    2016-11-01

    In this work, we examine the feasibility of triggering impact ionisation at sub-bandgap voltages through optimal utilisation of structural non-ideality induced electric field redistribution in the semiconductor film for an energy efficient steep switching junctionless (JL) transistor. While misalignment between front and back gates is often considered as a disadvantage due to loss of gate controllability, the work highlights its usefulness and applicability in nanoscale devices to engineer the electric field to enhance the product of current density (J) and electric field (E) and activate impact ionisation at sub-bandgap applied voltages. Results show that intentionally misaligned gates in silicon and germanium based JL devices exhibit an inclined conduction channel and achieve a nearly ideal value of steep subthreshold swing (˜ 1 mV decade-1) at room temperature. The work provides new viewpoints to realise energy efficient JL devices through the sharp increase of drain current from off-state to on-state achieved due to intentional misalignment between front and back gates.

  4. Rapid growth rates of syndepositional marine aragonite cements in steep marginal slope deposits, Bahamas and Belize

    SciTech Connect

    Grammer, G.M.; Ginsburg, R.N.; Swart, P.K.; McNeill, D.F. . Div. of Marine Geology); Jull, A.J.T. . NSF Accelerator Facility); Prezbindowski, D.R. )

    1993-09-01

    Growth rates of marine botryoidal aragonite cements from steep (35-45[degree]) marginal slope deposits in the Bahamas and Belize have been determined by accelerator mass spectrometer radiocarbon dating of samples taken at the base and top of individual botryoids. The pore-filling cements, which range from approximately 11,000-13,000 years old, grew at average rates of 8-10mm/100 yr with maximum rates > 25mm/100 yr. Radiocarbon dating of coexisting skeletal components indicates that cementation was syndepositional. Microsampling transects across individual botryoids for stable-isotope analyses show little variation in [delta][sup 31]C and [delta][sup 18]O, supporting the conclusion that cementation was extremely rapid. Although the cements show a progressive depletion in isotopic composition of approximately 1[per thousand]([delta][sup 13]C) and 2[per thousand]([delta][sup 18]O) from 13 ka to 11 ka, the average variation ([delta][sub 1]) within individual pore-filling cements, ranging in size 2 mm to 32 mm (bottom to top), was 0.11[per thousand]([delta][sup 13]C) and 0.14[per thousand]([delta][sup 18]O). Results of this study provide the first quantitative data on growth rates of marine carbonate cements in a marginal slope environment. The data indicate that marginal slope deposits may lithify within several tens of years and suggest that geologically instantaneous cementation may be critical in stabilizing steep carbonate slope deposits at or above angles of repose.

  5. Evidence for Holocene stability of steep slopes, northern Peruvian Andes, based on soils and radiocarbon dates

    USGS Publications Warehouse

    Miller, D.C.; Birkeland, P.W.; Rodbell, D.T.

    1993-01-01

    Radiocarbon dating and soil relationships indicate that landscapes in highaltitude glaciated valleys of the northern Peruvian Andes have been remarkably stable during the Holocene. Radiocarbon dates show that deglaciation was underway by 12 ka, and that slopes and alluvial fans at the bases of slopes were essentially stabilized by at least 8 ka. The soils consist of fine-grained loessial A horizons overlying Bw horizons in gravelly till or alluvial-fan gravel. Following deglaciation, widespread gullying took place in till on the steep (maximum angle: 37??) sideslopes of most valleys; the eroded material was deposited as fans at the bases of the slopes. Loess was then deposited as a fairly uniform blanket across most elements of the landscape. Soil formation began during or following loess deposition, and because soil-profile morphology is sufficiently similar at most sites, soil formation has been a dominant process during much of the Holocene. This remarkable stability, especially for such steep slopes, is attributed to a combination of tight packing of the till, permeability of the capping loess, rapid revegetation following ice retreat, and roots from the present grassland vegetation and possibly former forests. ?? 1993.

  6. Fast and local non-linear evolution of steep wave-groups on deep water: A comparison of approximate models to fully non-linear simulations

    SciTech Connect

    Adcock, T. A. A.; Taylor, P. H.

    2016-01-15

    The non-linear Schrödinger equation and its higher order extensions are routinely used for analysis of extreme ocean waves. This paper compares the evolution of individual wave-packets modelled using non-linear Schrödinger type equations with packets modelled using fully non-linear potential flow models. The modified non-linear Schrödinger Equation accurately models the relatively large scale non-linear changes to the shape of wave-groups, with a dramatic contraction of the group along the mean propagation direction and a corresponding extension of the width of the wave-crests. In addition, as extreme wave form, there is a local non-linear contraction of the wave-group around the crest which leads to a localised broadening of the wave spectrum which the bandwidth limited non-linear Schrödinger Equations struggle to capture. This limitation occurs for waves of moderate steepness and a narrow underlying spectrum.

  7. Effects of different steeping methods and storage on caffeine, catechins and gallic acid in bag tea infusions.

    PubMed

    Yang, Deng-Jye; Hwang, Lucy Sun; Lin, Jau-Tien

    2007-07-13

    Bag teas, packed 3g of ground black, green, oolong, paochoung and pu-erh tea leaves (the particle size used was 1-2mm), were steeped in 150 mL of 70, 85 or 100 degrees C hot water to study the effects of the number of steeping (the same bag tea was steeped repeatedly eight times, 30s each time, as done in China for making ceremonial tea) and varied steeping durations (0.5-4 min) on caffeine, catechins and gallic acid in tea infusions. The changes in tea infusions during storage at 4 or 25 degrees C for 0-48 h and the variations in these compounds of bag tea infused with 150 mL of 4 or 25 degrees C cold water for 0.5-16 h were also investigated. A HPLC method with a C18 column and a step gradient solvent system consisting of acetonitrile and 0.9% acetic acid in deionized water was used for analysis. Results for all kinds of tea samples showed that the second tea infusion contained the highest contents of caffeine, catechins and gallic acid when bag teas were steeped in 70 degrees C water. It was different from that steeped at 85 and 100 degrees C, the highest contents existed in the first infusion. These compounds decreased gradually in later infusions. Higher amounts of caffeine, catechins and gallic acid could be released from bag teas as hotter water was used. As steeping duration prolonged, these ingredients increased progressively, however, their levels were lower than that cumulated from the infusions with the identical bag tea prepared recurrently at the same temperature and time points. (-)-Gallocatechin gallate and (+)-catechin existed in these tea infusions rarely and could not be detected until a certain amount of them infusing. Except gallic acid that showed a significant increase and caffeine that exhibited no significant change, all kinds of catechins decreased appreciably after tea infusions were stored at 25 degrees C for 36 h; nevertheless, all of them showed no evident changes at 4 degrees C storage. The caffeine, catechins and gallic acid in tea

  8. A preliminary attempt to interpret the power spectrum of the solar five minute oscillations in terms of the global oscillation model

    NASA Technical Reports Server (NTRS)

    Kesley, D. A.

    1980-01-01

    The observed power spectrum of the solar five minute oscillations is discussed from the viewpoint that the oscillations are excited by turbulent convection. The observations place significant constraints on the theory and suggest constraints on the solar model structure. It is shown that the steep low frequency side of the peak in the power spectrum is more readily explained if the mixing length is greater than one scale height. The high frequency end of the power spectrum is also discussed.

  9. Dynamic changes in gamma-aminobutyric acid and glutamate decarboxylase activity in oats (Avena nuda L.) during steeping and germination.

    PubMed

    Xu, Jian Guo; Hu, Qing Ping; Duan, Jiang Lian; Tian, Cheng Rui

    2010-09-08

    Gamma-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter in the central nervous system and provides beneficial effects for human and other animals health. To accumulate GABA, samples from two different naked oat cultivars, Baiyan II and Bayou I, were steeped and germinated in an incubator. The content of GABA and glutamic acid as well as the activity of the glutamate decarboxylase (GAD) in oats during steeping and germination were investigated with an amino acid automatic analyzer. Compared with raw groats, an increase in GABA content of oat groats during steeping and germination was continuously observed for two oat cultivars. The activity of GAD increased greatly at the end of steeping and the second stage of germination for Baiyan II and Bayou I, respectively. Glutamic acid content of treated oat groats was significantly lower than that in raw groats until the later period of germination. GABA was correlated (p<0.01) significantly and positively with the glutamic acid rather than GAD activity in the current study. The results indicates that steeping and germination process under highly controlled conditions can effectively accumulate the GABA in oat groats for Baiyan II and Bayou I, which would greatly facilitate production of nutraceuticals or food ingredients that enable consumers to gain greater access to the health benefits of oats. However, more assays need to be further performed with more oat cultivars.

  10. On the formulation of new explicit conditions for steepness from a former result of N.N. Nekhoroshev

    NASA Astrophysics Data System (ADS)

    Schirinzi, Gabriella; Guzzo, Massimiliano

    2013-07-01

    The application of the Nekhoroshev theorem to many problems arising in different fields of Physics and Astronomy depends on a non-degeneracy property, called steepness, that a suitable Hamiltonian approximation must satisfy. Since steepness is implicitly defined, we have the problem of recognizing whether a given function is steep or not. For this purpose, we here consider some sufficient conditions for steepness provided by Nekhoroshev in 1979, based on the solvability of a collection of systems depending on the number n of degrees of freedom, the derivatives of the function up to a certain order r, and some auxiliary parameters. These conditions are really explicit only for r = 2, corresponding to quasi-convexity, and for r = 3. Instead, for r ⩾ 4, the conditions are implicit, since they require an elaborate computation of the closure of a certain set. In this paper, we first revisit Nekhoroshev's result and we show that the number of parameters in the collections of systems can be suitably reduced. Then, we show that for r = 4 Nekhoroshev's result is interesting only for n = 2, 3, and 4, and in these cases we find explicit conditions for steepness which are formulated in a purely algebraic form.

  11. On the Nature of Neutral-Line-Associated Radio Sources

    NASA Astrophysics Data System (ADS)

    Yasnov, Leonid V.

    2014-04-01

    A number of authors claimed that radio sources above the neutral line of the magnetic field in solar active regions are due to non-thermal emission. This study shows that the thermal mechanism explains the radio emission from such sources. Models similar to those used for interpreting cyclotron lines were used in this study. Such models account for a steep decline in the spectrum at high frequencies and a low degree of polarization. The magnetic field between the two sunspots with an anti-parallel magnetic field has a lower gradient than the field above the sunspots. This, combined with the possibly high temperature in coronal loops connecting the sunspots, leads to the following conclusions. The optical thickness of the gyroresonance layers is increased and leads to more effective radiation at a harmonic number of 4 or 5. The lower gradient of the field between the sunspots also results in more rapid growth of emission intensity with increasing wavelength in this region than in the regions immediately above the sunspots. Additionally, the spatial averaging of the source structure due to the antenna beam pattern leads to a decrease in the degree of polarization in the region between the sunspots.

  12. Fast, three-dimensional, MR Imaging for polymer gel dosimetric applications involving high dose and steep dose gradients

    NASA Astrophysics Data System (ADS)

    Sandilos, Panagiotis; Baras, Panagiotis; Georgiou, Evangelos; Dardoufas, Konstantinos; Karaiskos, Pantelis; Papagiannis, Panagiotis; Paschalis, Theodoros; Tatsis, Elias; Torrens, Michael; Vlahos, Lampros

    2006-12-01

    Polymer gels constitute water equivalent integrating detectors, which, combined with magnetic resonance imaging (MRI), can provide accurate three dimensional (3D) dose distributions in contemporary radiotherapy applications where the small field dimensions and steep dose gradients induce limitations to conventional dosimeters. One of the main obstacles for adapting the method for routine use in the clinical setting is the cost effectiveness of the MRI readout method. Currently, optimized Carr-Purcell-Meiboom-Gill (CPMG) multiple spin echo imaging pulse sequences are commonly used which however result in long imaging times. This work evaluates the efficiency of 3D, dual-echo, k-space segmented turbo spin echo (TSE) scanning sequences for accurate dosimetry with sub-millimetre spatial resolution in strenuous radiation therapy applications. PABIG polymer gel dosimeters were irradiated with an 192Ir High Dose Rate brachytherapy source, the 4 mm and 8 mm collimator helmets of a gamma knife unit and a custom made x-knife collimator of 1 cm diameter. Profile and dose distribution measurements using TSE are benchmarked against corresponding findings obtained by the commonly used, but time consuming, CPMG sequence as well as treatment planning calculations, Monte Carlo (MC) simulations and film measurements. The implementation of a high Turbo factor was found to provide comparable accuracy, allowing a 64-fold MRI scan acceleration compared to conventional multi-echo sequences. The availability of TSE sequences in typical MRI installations greatly facilitates the introduction of polymer gel dosimetry in the clinical environment as a practicable tool for the determination of full 3D dose distributions in contemporary radiotherapy applications.

  13. Flood and debris flow interactions with roads promote the invasion of exotic plants along steep mountain streams, western Oregon

    NASA Astrophysics Data System (ADS)

    Watterson, Nicholas A.; Jones, Julia A.

    2006-08-01

    This study examines the interactions among geomorphic and biogeographic processes that govern the invasion by two contrasting exotic plant species—a shrub, scotch broom ( Cytisus scoparius) and an herb, foxglove ( Digitalis purpurea), over several decades of road and stream networks in the H.J. Andrews Experimental Forest in western Oregon. Distributions of C. scoparius and D. purpurea were mapped along hillslopes and streams in 1993, 2002, and 2003. The mapped distributions were related to debris flow pathways and changes in stream morphology interpreted from field surveys and air photos over the period 1993 to 2003. Laboratory trials examined the response of seed germination to scarification (to test effects of transport by debris flows), soaking (to test effects of fluvial transport), and substrate texture (to test effects on establishment). C. scoparius and D. purpurea were present along roads and in clearcuts in the Andrews Forest from the 1970s to 2003, but invaded the stream (Lookout Creek) only after debris flows and floods during an extreme storm in 1996. Laboratory trials demonstrated that seeds could germinate on a variety of substrates after scarification and flood transport. Mapping and air photo/GIS analysis indicated that the distributions of exotic plants were located on freshly scoured bars and floodplains adjacent to the active channel, downstream of seed sources along roads that were connected to the main stem of Lookout Creek by road ditch drainage systems, and debris flow paths. This paper outlines a conceptual model for the invasion of exotic plants, highlighting the connectivity between road and stream networks provided by geomorphic processes in steep forested landscapes.

  14. Lensing corrections to features in the angular two-point correlation function and power spectrum

    SciTech Connect

    LoVerde, Marilena; Hui, Lam; Gaztanaga, Enrique

    2008-01-15

    It is well known that magnification bias, the modulation of galaxy or quasar source counts by gravitational lensing, can change the observed angular correlation function. We investigate magnification-induced changes to the shape of the observed correlation function w({theta}), and the angular power spectrum C{sub l}, paying special attention to the matter-radiation equality peak and the baryon wiggles. Lensing effectively mixes the correlation function of the source galaxies with that of the matter correlation at the lower redshifts of the lenses distorting the observed correlation function. We quantify how the lensing corrections depend on the width of the selection function, the galaxy bias b, and the number count slope s. The lensing correction increases with redshift and larger corrections are present for sources with steep number count slopes and/or broad redshift distributions. The most drastic changes to C{sub l} occur for measurements at high redshifts (z > or approx. 1.5) and low multipole moment (l < or approx. 100). For the source distributions we consider, magnification bias can shift the location of the matter-radiation equality scale by 1%-6% at z{approx}1.5 and by z{approx}3.5 the shift can be as large as 30%. The baryon bump in {theta}{sup 2}w({theta}) is shifted by < or approx. 1% and the width is typically increased by {approx}10%. Shifts of > or approx. 0.5% and broadening > or approx. 20% occur only for very broad selection functions and/or galaxies with (5s-2)/b > or approx. 2. However, near the baryon bump the magnification correction is not constant but is a gently varying function which depends on the source population. Depending on how the w({theta}) data is fitted, this correction may need to be accounted for when using the baryon acoustic scale for precision cosmology.

  15. Steep switching characteristics of single-gated feedback field-effect transistors

    NASA Astrophysics Data System (ADS)

    Kim, Minsuk; Kim, Yoonjoong; Lim, Doohyeok; Woo, Sola; Cho, Kyoungah; Kim, Sangsig

    2017-02-01

    In this study, we propose newly designed feedback field-effect transistors that utilize the positive feedback of charge carriers in single-gated silicon channels to achieve steep switching behaviors. The band diagram, I-V characteristics, subthreshold swing, and on/off current ratio are analyzed using a commercial device simulator. Our proposed feedback field-effect transistors exhibit subthreshold swings of less than 0.1 mV dec-1, an on/off current ratio of approximately 1011, and an on-current of approximately 10-4 A at room temperature, demonstrating that the switching characteristics are superior to those of other silicon-based devices. In addition, the device parameters that affect the device performance, hysteresis characteristics, and temperature-dependent device characteristics are discussed in detail.

  16. Effects of bedrock groundwater on landslide occurrences in a steep headwater catchment

    NASA Astrophysics Data System (ADS)

    Kosugi, K.; Fujimoto, M.; Sando, Y.; Mizuyama, T.; Kinoshita, A.

    2011-12-01

    Previous studies have shown that the formation of groundwater in the soil mantle greatly affects slope instability on steep landscapes. To predict landslides, mathematical models based on a geographic information system, which organize geographic data such as information on upslope contributing areas and the local slope gradient, have been developed and tested. Although such models can be used to calculate the topographically driven convergence of rainwater and groundwater table developments in the soil mantle, thus providing a spatially distributed prediction of landslide occurrences, the accuracy of these mathematical models is still limited, mainly because they ignore storm responses in underlying bedrock. Recent research has provided credible information on the importance of bedrock groundwater on surface hydrological processes in headwater catchments. To elucidate the effects of bedrock groundwater, the dynamics of bedrock groundwater should be measured directly. However, intensive monitoring of bedrock groundwater is rare in mountains with steep topography. Consequently, how bedrock groundwater controls landslides in a steep headwater catchment is in dispute. In this study, we conducted long-term hydrological observations using densely nested bedrock wells along with monitoring of discharge hydrograph and soil mantle groundwater in a steep headwater catchment underlain by granitic bedrock. Bedrock wells with depths of 7-78 m were drilled at 31 points within the 2.10-ha catchment. Results showed that a hollow of bedrock aquifer was located at a ridge in the surface topography, clearly indicating bedrock groundwater flow across topographic divides. Around a point where the bedrock groundwater exfiltrated, we found scars of landslides. Such landslides cannot be explained by mathematical hydrology models, which calculate the topographically driven convergence of rainwater in the soil mantle. Moreover, at a point along the main hollow of the watershed, we observed

  17. Operation regimes and electrical transport of steep slope Schottky Si-FinFETs

    NASA Astrophysics Data System (ADS)

    Jeon, Dae-Young; Zhang, Jian; Trommer, Jens; Park, So Jeong; Gaillardon, Pierre-Emmanuel; De Micheli, Giovanni; Mikolajick, Thomas; Weber, Walter M.

    2017-02-01

    In the quest for energy efficient circuits, considerable focus has been given to steep slope and polarity-controllable devices, targeting low supply voltages and reduction of transistor count. The recently proposed concept of the three-independent gated Si-FinFETs with Schottky-barriers (SBs) has proven to bring both functionalities even in a single device. However, the complex combination of transport properties including Schottky emission and weak impact ionization as well as the body effect makes the design of such devices challenging. In this work, we perform a deep electrical characterization analysis to visualize and decouple the different operation regimes and electrical properties of the SB Si-FinFETs using a graphical transport map. From these, we give important guidelines for the design of future devices.

  18. Dual-Gate p-GaN Gate High Electron Mobility Transistors for Steep Subthreshold Slope.

    PubMed

    Bae, Jong-Ho; Lee, Jong-Ho

    2016-05-01

    A steep subthreshold slope characteristic is achieved through p-GaN gate HEMT with dual-gate structure. Obtained subthreshold slope is less than 120 μV/dec. Based on the measured and simulated data obtained from single-gate device, breakdown of parasitic floating-base bipolar transistor and floating gate charged with holes are responsible to increase abruptly in drain current. In the dual-gate device, on-current degrades with high temperature but subthreshold slope is not changed. To observe the switching speed of dual-gate device and transient response of drain current are measured. According to the transient responses of drain current, switching speed of the dual-gate device is about 10(-5) sec.

  19. Development of a digital automatic control law for steep glideslope capture and flare

    NASA Technical Reports Server (NTRS)

    Halyo, N.

    1977-01-01

    A longitudinal digital guidance and control law for steep glideslopes using MLS (Microwave Landing System) data is developed for CTOL aircraft using modern estimation and control techniques. The control law covers the final approach phases of glideslope capture, glideslope tracking, and flare to touchdown for automatic landings under adverse weather conditions. The control law uses a constant gain Kalman filter to process MLS and body-mounted accelerometer data to form estimates of flight path errors and wind velocities including wind shear. The flight path error estimates and wind estimates are used for feedback in generating control surface commands. Results of a digital simulation of the aircraft dynamics and the guidance and control law are presented for various wind conditions.

  20. Development of a digital integrated automatic landing system /DIALS/ for steep approach and landing

    NASA Technical Reports Server (NTRS)

    Halyo, N.; Hueschen, R. M.

    1981-01-01

    This paper describes the development of a three-dimensional digital integrated automatic landing system (DIALS) for a small commercial jet transport. The system uses the Microwave Landing System (MLS), body-mounted accelerometers, as well as on-board sensors usually available on commercial aircraft, but does not require inertial platforms. The system development uses modern digital control techniques. The phases of flight considered are the localizer and glideslope capture, which may be performed simultaneously or sequentially, localizer and glideslope track (hold), crab/decrab, and flare to touchdown. The system captures, tracks and flares from steep glideslopes (2.5 - 5.5 deg) selected prior to glideslope capture. The results of a nonlinear simulation are presented.

  1. Back bias induced dynamic and steep subthreshold swing in junctionless transistors

    SciTech Connect

    Parihar, Mukta Singh; Kranti, Abhinav

    2014-07-21

    In this work, we analyze back bias induced steep and dynamic subthreshold swing in junctionless double gate transistors operated in the asymmetric mode. This impact ionization induced dynamic subthreshold swing is explained in terms of the ratio between minimum hole concentration and peak electron concentration, and the dynamic change in the location of the conduction channel with applied front gate voltage. The reason for the occurrence of impact ionization at sub-bandgap drain voltages in silicon junctionless transistors is also accounted for. The optimum junctionless transistor operating at a back gate bias of −0.9 V, achieves over 5 orders of change in drain current at a gate overdrive of 200 mV and drain bias of 1 V. These results for junctionless transistors are significantly better than those exhibited by silicon tunnel field effect transistors operating at the same drain bias.

  2. Simulation of cable and winding response to steep-fronted voltage waves

    SciTech Connect

    Hyypio, D.B.

    1995-12-31

    The detrimental effect of steep-fronted voltage waves impinging on machine windings has become a subject of concern with the advent of fast switching IGBT inverters. A simulation model using finite difference techniques has been developed which predicts observed phenomena such as machine terminal overvoltage transients and nonuniform voltage distribution within the winding. This analysis tool, unlike previous methods discussed under the background survey section of the paper, includes the feeder cable as part of the simulation to reveal the effect of its characteristic impedance and length upon the temporal machine winding voltage distribution. Simulation results are compared to actual measurement. The use of this tool in inverter waveshaping, cable selection and winding design is briefly considered.

  3. Impact of steep-front short-duration impulse on electric power system insulation

    SciTech Connect

    Burrage, L M; Veverka, E F; Shaw, J H; McConnell, B W

    1991-04-01

    This research effort required the performance evaluation of three specific insulation systems in common usage by electric power transmission and distribution utilities under stresses imposed by: three characteristic impulse waveforms (two waves representative of steep-front short duration (SFSD) impulses and one representative of lightning), the cumulative effect of multiple shots'' of each pulse, 60 Hz voltage, and, where appropriate, and mechanical load. The insulation systems evaluated are the cellulose-paper/oil combination typical of power transformer and condenser bushing usage, the cellulose-paper/enamel/oil combination used in distribution transformer construction, and the porcelain/air combination representing transmission and distribution line structural insulation. 4 refs., 94 figs., 11 tabs.

  4. The effects of steep-front, short-duration impulses on power distribution components

    SciTech Connect

    Miller, D.B.; Lux, A.E.; Grzybowski, Stanislaw; Barnes, P.R.

    1989-07-01

    A line type pulser has been developed to test the effects of steep-front, short duration (SFSD) pulses on distribution components. Risetime is 50-100 ns, and pulse duration is on the order of 300 ns. Terminators often shattered or punctured rather than flashing over. Insulator flashover voltage is approximately 1.5 times CFO for standard lightning impulses. Arresters exhibit an inductive character, with SFSD peak voltage at 10 kA approximately 4--5 times the 8 /times/ 20 microsecond 10 kA discharge voltage. Polyethylene insulated cable has a characteristic degradation in which failure voltage decreases with number of SFSD pulses. 7 refs., 12 figs., 2 tabs.

  5. Continuous monitoring of bedload discharge in a small, steep sandy channel

    NASA Astrophysics Data System (ADS)

    Lucía, Ana; Recking, Alain; Martín-Duque, José F.; Storz-Peretz, Yael; Laronne, Jonathan B.

    2013-08-01

    This paper reports on bedload flux and texture monitored in a natural, steep, sandy ephemeral channel draining a small gullied sandy watershed, the Barranca de los Pinos (1.32 ha), Spain. Bedload flux was continuously monitored with two independent Reid-type slot samplers; bedload texture was determined from the sediment collected in the samplers. Channel morphology was surveyed with a high spatial resolution with a Terrestrial Laser Scanner. The monitored instantaneous bedload fluxes are among the highest measured in natural rivers, characterized by high temporal and spatial variability related to the presence of bedforms, shallow bars and sand sheets, and to the reworking of the dry bed between and at the end of individual flow events. The grain size distribution of the bedload indicates equal mobility; but bedload texture fluctuates, depicting the transport of coarser bar surfaces and of finer-grained anabranch surfaces as well as of the overall bed subsurface.

  6. Non-linear random wave kinematics models verified against measurements in steep waves

    SciTech Connect

    Stansberg, C.T.

    1996-12-31

    Measurements from an earlier experiment on random wave kinematics are compared to four different numerical wave models. The models are: Second-order random wave model, Hybrid wave model, Wheeler stretching, and a modified Wheeler stretching method. Wave elevation, horizontal fluid particle velocities and corresponding accelerations in steep individual waves are included in the comparison. Spatial velocity profiles, as well as time history profiles showing the kinematics at certain fixed vertical levels, are shown. It is found that the second order and the hybrid wave models generally predict the measured kinematics (velocities as well as accelerations) reasonably well. The Wheeler stretching method predicts velocities quite well at the free surface of crest peaks, while it underpredicts the velocities further below in the wave zone fluid. With the modified Wheeler stretching procedure this is improved.

  7. Mechanics of gravitational spreading of steep-sided ridges («sackung»)

    USGS Publications Warehouse

    Savage, W.Z.; Varnes, D.J.

    1987-01-01

    Large-scale gravitational spreading of steep-sided ridges characterized by linear fissures, trenches, and uphill-facing scarps high on the sides and tops of ridges are known worldwide. Such spreading, termed sackung, is commonly attributed to pervasive plastic deformation of a rock mass, and is here analyzed as such. Beginning with a previously developed exact elastic solution for gravity-induced stresses in a symmetric ridge, stresses calculated from the exact solution are used in the Coulomb failure criterion to determine the extent of ridge failure under self-weight. Finally, when the regions of failure are established, a plastic flow solution is applied to predict the location of and sense of movement on upward-facing scarps near ridge crests and other features common in sackung. ?? 1987 International Assocaition of Engineering Geology.

  8. Utilization of the buffering capacity of corn steep liquor in bacterial cellulose production by Acetobacter xylinum.

    PubMed

    Noro, N; Sugano, Y; Shoda, M

    2004-04-01

    Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC). Using a pH sensor for the accurate control of pH, which is one of the most critical factors for efficient BC production, is difficult especially in a baffled shake-flask and an airlift reactor. The buffering capacity of corn steep liquor (CSL) was estimated by measuring beta (buffering capacity) values in advance and was used to maintain the pH within the optimal range during the production of BC. When CSL was added to either a shake-flask, a stirred-tank reactor or an airlift reactor, BC production was almost the same as that in cultivations where pH was controlled manually or by a pH sensor.

  9. Collisionless absorption of light waves incident on overdense plasmas with steep density gradients

    SciTech Connect

    Yang, T.Y.B.; Kruer, W.L.; Langdon, A.B.

    1995-07-31

    Collisionless absorption of laser light incident on overdense plasmas with steep density gradients is studied analytically and numerically. For the normal incidence case, it is shown that both sheath inverse bremsstrahlung and the anomalous skin effect are limiting cases of the same collisionless absorption mechanism. Using particle-in-cell (PIC) plasma simulations, the effects of finite sheath-transit time and finite density gradient are investigated. The analyses are extended to oblique incident cases. For p-polarized obliquely incident light, the results are significantly different from those for the normal incidence case. Most noticeable is the absorption enhancement for the p-polarized light due to the interaction of the electrons with the normal (parallel to the density gradient) component of the laser electric field in the sheath region.

  10. Deep observations of the Super-CLASS supercluster at 325 MHz with the GMRT: the low-frequency source catalogue

    NASA Astrophysics Data System (ADS)

    Riseley, C. J.; Scaife, A. M. M.; Hales, C. A.; Harrison, I.; Birkinshaw, M.; Battye, R. A.; Beswick, R. J.; Brown, M. L.; Casey, C. M.; Chapman, S. C.; Demetroullas, C.; Hung, C.-L.; Jackson, N. J.; Muxlow, T.; Watson, B.

    2016-10-01

    We present the results of 325 MHz Giant Metrewave Radio Telescope observations of a supercluster field, known to contain five Abell clusters at redshift z ˜ 0.2. We achieve a nominal sensitivity of 34 μJy beam-1 towards the phase centre. We compile a catalogue of 3257 sources with flux densities in the range 183 μ {Jy}-1.5 {Jy} within the entire ˜6.5 deg2 field of view. Subsequently, we use available survey data at other frequencies to derive the spectral index distribution for a sub-sample of these sources, recovering two distinct populations - a dominant population which exhibit spectral index trends typical of steep-spectrum synchrotron emission, and a smaller population of sources with typically flat or rising spectra. We identify a number of sources with ultrasteep spectra or rising spectra for further analysis, finding two candidate high-redshift radio galaxies and three gigahertz-peaked-spectrum radio sources. Finally, we derive the Euclidean-normalized differential source counts using the catalogue compiled in this work, for sources with flux densities in excess of 223 μJy. Our differential source counts are consistent with both previous observations at this frequency and models of the low-frequency source population. These represent the deepest source counts yet derived at 325 MHz. Our source counts exhibit the well-known flattening at mJy flux densities, consistent with an emerging population of star-forming galaxies; we also find marginal evidence of a downturn at flux densities below 308 μJy, a feature so far only seen at 1.4 GHz.

  11. Correction of Excessive Precipitation Over Steep and High Mountains in a General Circulation Model

    NASA Technical Reports Server (NTRS)

    Chao, Winston C.

    2012-01-01

    Excessive precipitation over steep and high mountains (EPSM) is a well-known problem in GCMs and meso-scale models. This problem impairs simulation and data assimilation products. Among the possible causes investigated in this study, we found that the most important one, by far, is a missing upward transport of heat out of the boundary layer due to the vertical circulations forced by the daytime upslope winds, which are forced by the heated boundary layer on subgrid-scale slopes. These upslope winds are associated with large subgrid-scale topographic variation, which is found over steep and high mountains. Without such subgridscale heat ventilation, the resolvable-scale upslope flow in the boundary layer generated by surface sensible heat flux along the mountain slopes is excessive. Such an excessive resolvablescale upslope flow combined with the high moisture content in the boundary layer results in excessive moisture transport toward mountaintops, which in turn gives rise to EPSM. Other possible causes of EPSM that we have investigated include 1) a poorly-designed horizontal moisture flux in the terrain-following coordinates, 2) the condition for cumulus convection being too easily satisfied at mountaintops, 3) the presence of conditional instability of the computational kind, and 4) the absence of blocked flow drag. These are all minor or inconsequential. We have parameterized the ventilation effects of the subgrid-scale heated-slope-induced vertical circulation (SHVC) by removing heat from the boundary layer and depositing it in layers higher up when the topographic variance exceeds a critical value. Test results using NASA/Goddard's GEOS-S GCM have shown that this largely solved the EPSM problem.

  12. Model simulations of flood and debris flow timing in steep catchments after wildfire

    NASA Astrophysics Data System (ADS)

    Rengers, F. K.; McGuire, L. A.; Kean, J. W.; Staley, D. M.; Hobley, D. E. J.

    2016-08-01

    Debris flows are a typical hazard on steep slopes after wildfire, but unlike debris flows that mobilize from landslides, most postwildfire debris flows are generated from water runoff. The majority of existing debris flow modeling has focused on landslide-triggered debris flows. In this study we explore the potential for using process-based rainfall-runoff models to simulate the timing of water flow and runoff-generated debris flows in recently burned areas. Two different spatially distributed hydrologic models with differing levels of complexity were used: the full shallow water equations and the kinematic wave approximation. Model parameter values were calibrated in two different watersheds, spanning two orders of magnitude in drainage area. These watersheds were affected by the 2009 Station Fire in the San Gabriel Mountains, CA, USA. Input data for the numerical models were constrained by time series of soil moisture, flow stage, and rainfall collected at field sites, as well as high-resolution lidar-derived digital elevation models. The calibrated parameters were used to model a third watershed in the burn area, and the results show a good match with observed timing of flow peaks. The calibrated roughness parameter (Manning's n) was generally higher when using the kinematic wave approximation relative to the shallow water equations, and decreased with increasing spatial scale. The calibrated effective watershed hydraulic conductivity was low for both models, even for storms occurring several months after the fire, suggesting that wildfire-induced changes to soil-water infiltration were retained throughout that time. Overall, the two model simulations were quite similar suggesting that a kinematic wave model, which is simpler and more computationally efficient, is a suitable approach for predicting flood and debris flow timing in steep, burned watersheds.

  13. Laboratory investigation and direct numerical simulation of wind effect on steep surface waves

    NASA Astrophysics Data System (ADS)

    Troitskaya, Yuliya; Sergeev, Daniil; Druzhinin, Oleg; Ermakova, Olga

    2015-04-01

    The small scale ocean-atmosphere interaction at the water-air interface is one of the most important factors determining the processes of heat, mass, and energy exchange in the boundary layers of both geospheres. Another important aspect of the air-sea interaction is excitation of surface waves. One of the most debated open questions of wave modeling is concerned with the wind input in the wave field, especially for the case of steep and breaking waves. Two physical mechanisms are suggested to describe the excitation of finite amplitude waves. The first one is based on the treatment of the wind-wave interaction in quasi-linear approximation in the frameworks of semi-empirical models of turbulence of the low atmospheric boundary layer. An alternative mechanism is associated with separation of wind flow at the crests of the surface waves. The "separating" and "non-separating" mechanisms of wave generation lead to different dependences of the wind growth rate on the wave steepness: the latter predicts a decrease in the increment with wave steepness, and the former - an increase. In this paper the mechanism of the wind-wave interaction is investigated basing on physical and numerical experiments. In the physical experiment, turbulent airflow over waves was studied using the video-PIV method, based on the application of high-speed video photography. Alternatively to the classical PIV technique this approach provides the statistical ensembles of realizations of instantaneous velocity fields. Experiments were performed in a round wind-wave channel at Institute of Applied Physics, Russian Academy of Sciences. A fan generated the airflow with the centerline velocity 4 m/s. The surface waves were generated by a programmed wave-maker at the frequency of 2.5 Hz with the amplitudes of 0.65 cm, 1.4 cm, and 2 cm. The working area (27.4 × 10.7 cm2) was at a distance of 3 m from the fan. To perform the measurements of the instantaneous velocity fields, spherical polyamide

  14. Model simulations of flood and debris flow timing in steep catchments after wildfire

    USGS Publications Warehouse

    Rengers, Francis; Mcguire, Luke; Kean, Jason W.; Staley, Dennis M.; Hobley, D.E.J

    2016-01-01

    Debris flows are a typical hazard on steep slopes after wildfire, but unlike debris flows that mobilize from landslides, most post-wildfire debris flows are generated from water runoff. The majority of existing debris-flow modeling has focused on landslide-triggered debris flows. In this study we explore the potential for using process-based rainfall-runoff models to simulate the timing of water flow and runoff-generated debris flows in recently burned areas. Two different spatially distributed hydrologic models with differing levels of complexity were used: the full shallow water equations and the kinematic wave approximation. Model parameter values were calibrated in two different watersheds, spanning two orders of magnitude in drainage area. These watersheds were affected by the 2009 Station Fire in the San Gabriel Mountains, CA, USA. Input data for the numerical models were constrained by time series of soil moisture, flow stage, and rainfall collected at field sites, as well as high-resolution lidar-derived digital elevation models. The calibrated parameters were used to model a third watershed in the burn area, and the results show a good match with observed timing of flow peaks. The calibrated roughness parameter (Manning's $n$) was generally higher when using the kinematic wave approximation relative to the shallow water equations, and decreased with increasing spatial scale. The calibrated effective watershed hydraulic conductivity was low for both models, even for storms occurring several months after the fire, suggesting that wildfire-induced changes to soil-water infiltration were retained throughout that time. Overall the two model simulations were quite similar suggesting that a kinematic wave model, which is simpler and more computationally efficient, is a suitable approach for predicting flood and debris flow timing in steep, burned watersheds.

  15. Quantifying irreversible movement in steep, fractured bedrock permafrost on Matterhorn (CH)

    NASA Astrophysics Data System (ADS)

    Weber, Samuel; Beutel, Jan; Faillettaz, Jérome; Hasler, Andreas; Krautblatter, Michael; Vieli, Andreas

    2017-02-01

    Understanding rock slope kinematics in steep, fractured bedrock permafrost is a challenging task. Recent laboratory studies have provided enhanced understanding of rock fatigue and fracturing in cold environments but were not successfully confirmed by field studies. This study presents a unique time series of fracture kinematics, rock temperatures and environmental conditions at 3500 m a. s. l. on the steep, strongly fractured Hörnligrat of the Matterhorn (Swiss Alps). Thanks to 8 years of continuous data, the longer-term evolution of fracture kinematics in permafrost can be analyzed with an unprecedented level of detail. Evidence for common trends in spatiotemporal pattern of fracture kinematics could be found: a partly reversible seasonal movement can be observed at all locations, with variable amplitudes. In the wider context of rock slope stability assessment, we propose separating reversible (elastic) components of fracture kinematics, caused by thermoelastic strains, from the irreversible (plastic) component due to other processes. A regression analysis between temperature and fracture displacement shows that all instrumented fractures exhibit reversible displacements that dominate fracture kinematics in winter. Furthermore, removing this reversible component from the observed displacement enables us to quantify the irreversible component. From this, a new metric - termed index of irreversibility - is proposed to quantify relative irreversibility of fracture kinematics. This new index can identify periods when fracture displacements are dominated by irreversible processes. For many sensors, irreversible enhanced fracture displacement is observed in summer and its initiation coincides with the onset of positive rock temperatures. This likely indicates thawing-related processes, such as meltwater percolation into fractures, as a forcing mechanism for irreversible displacements. For a few instrumented fractures, irreversible displacements were found at the

  16. The Supercritical Pile Gamma-Ray Burst Model: The GRB Afterglow Steep Decline and Plateau Phase

    NASA Technical Reports Server (NTRS)

    Sultana, Joseph; Kazanas, D.; Mastichiadis, A.

    2013-01-01

    We present a process that accounts for the steep decline and plateau phase of the Swift X-Ray Telescope (XRT) light curves, vexing features of gamma-ray burst (GRB) phenomenology. This process is an integral part of the "supercritical pile" GRB model, proposed a few years ago to account for the conversion of the GRB kinetic energy into radiation with a spectral peak at E(sub pk) is approx. m(sub e)C(exp 2). We compute the evolution of the relativistic blast wave (RBW) Lorentz factor Gamma to show that the radiation-reaction force due to the GRB emission can produce an abrupt, small (approx. 25%) decrease in Gamma at a radius that is smaller (depending on conditions) than the deceleration radius R(sub D). Because of this reduction, the kinematic criticality criterion of the "supercritical pile" is no longer fulfilled. Transfer of the proton energy into electrons ceases and the GRB enters abruptly the afterglow phase at a luminosity smaller by approx. m(sub p)/m(sub e) than that of the prompt emission. If the radius at which this slow-down occurs is significantly smaller than R(sub D), the RBW internal energy continues to drive the RBW expansion at a constant (new) Gamma and its X-ray luminosity remains constant until R(sub D) is reached, at which point it resumes its more conventional decay, thereby completing the "unexpected" XRT light curve phase. If this transition occurs at R is approx. equal to R(sub D), the steep decline is followed by a flux decrease instead of a "plateau," consistent with the conventional afterglow declines. Besides providing an account of these peculiarities, the model suggests that the afterglow phase may in fact begin before the RBW reaches R is approx. equal to R(sub D), thus providing novel insights into GRB phenomenology.

  17. Dual-Frequency Observations of 140 Compact, Flat-Spectrum Active Galactic Nuclei for Scintillation-Induced Variability

    NASA Technical Reports Server (NTRS)

    Koay, J. Y.; Macquart, J.- P.; Rickett, B. J.; Bignall, H. E.; Lovell, J. E. J.; Reynolds, C.; Jauncey, D. L.; Pursimo, T.; Kedziora-Chudczer, L.; Ojha, R.

    2012-01-01

    The 4.9 GHz Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey detected a drop in Interstellar Scintillation (ISS) for sources at red shifts z > or approx. 2, indicating an apparent increase in angular diameter or a decrease in flux density of the most compact components of these sources, relative to their extended emission. This can result from intrinsic source size effects or scatter broadening in the Intergalactic Medium (IGM) , in excess of the expected (1+z)1/2 angular diameter scaling of brightness temperature limited sources resulting from cosmological expansion. We report here 4.9 GHz and 8.4 GHz observations and data analysis for a sample of 140 compact, fiat-spectrum sources which may allow us to determine the origin of this angular diameter-redshift relation by exploiting their different wavelength dependences. In addition to using ISS as a cosmological probe, the observations provide additional insight into source morphologies and the characteristics of ISS. As in the MASIV Survey, the variability of the sources is found to be significantly correlated with line-of-sight H(alpha) intensities, confirming its link with ISS. For 25 sources, time delays of about 0.15 to 3 days are observed between the scintillation patterns at both frequencies, interpreted as being caused by a shift in core positions when probed at different optical depths. Significant correlation is found between ISS amplitudes and source spectral index; in particular, a large drop in ISS amplitudes is observed at alpha < -0.4 confirming that steep spectrum sources scintillate less. We detect a weakened redshift dependence of ISS at 8.4 GHz over that at 4.9 GHz, with the mean variance at 4-day timescales reduced by a factor of 1.8 in the z > 2 sources relative to the z < 2 sources, as opposed to the factor of 3 decrease observed at 4.9 GHz. This suggests scatter broadening in the IGM, but the interpretation is complicated by subtle selection effects that will be explored

  18. The first VLBI image of an infrared-faint radio source

    NASA Astrophysics Data System (ADS)

    Middelberg, E.; Norris, R. P.; Tingay, S.; Mao, M. Y.; Phillips, C. J.; Hotan, A. W.

    2008-11-01

    Context: We investigate the joint evolution of active galactic nuclei and star formation in the Universe. Aims: In the 1.4 GHz survey with the Australia Telescope Compact Array of the Chandra Deep Field South and the European Large Area ISO Survey - S1 we have identified a class of objects which are strong in the radio but have no detectable infrared and optical counterparts. This class has been called Infrared-Faint Radio Sources, or IFRS. 53 sources out of 2002 have been classified as IFRS. It is not known what these objects are. Methods: To address the many possible explanations as to what the nature of these objects is we have observed four sources with the Australian Long Baseline Array. Results: We have detected and imaged one of the four sources observed. Assuming that the source is at a high redshift, we find its properties in agreement with properties of Compact Steep Spectrum sources. However, due to the lack of optical and infrared data the constraints are not particularly strong.

  19. Diffuse radio emission around FR II sources as exemplified by 3C452

    NASA Astrophysics Data System (ADS)

    Wiita, Paul J.; Sirothia, S. K.; Gopal-Krishna, ..

    2014-01-01

    We have discovered a pair of megaparsec size radio lobes of extremely steep spectrum straddling the well-known classical double radio source 3C452. For the past several decades 3C452 has been regarded as a textbook example of an edge-brightened double radio source of Fanaroff-Riley type II (FR II) but we show it to be a bonafide "double-double" radio galaxy (DDRG). The inner double fed by the jets has evolved into a perfectly normal FR II radio source. Thus, 3C452 presents a uniquely robust example of recurrent nuclear activity in which the restarted jets are expanding non-relativistically within the relic synchrotron plasma from an earlier active phase. This situation contrasts markedly with the strikingly narrow inner doubles observed in a few other DDRGs that have been interpreted in terms of compression of the synchrotron plasma of the relic outer lobes at the relativistic bow-shocks driven by the near ballistic propagation of the two inner jets through the relic plasma. We also present additional examples of the occurrence of faded outer lobes around well defined FRII sources, using our deep GMRT images at meter wavelengths processed with AIPS++ software. We also examine the statistics of the occurrence of such sources using a flux density limited sample. A key ramification of our findings are that they caution against the use of FR II classical double radio sources for testing cosmological models and unification schemes for active galactic nuclei.

  20. Discovery of a Highly Variable Dipping Ultraluminous X-Ray Source in M94

    NASA Astrophysics Data System (ADS)

    Lin, Dacheng; Irwin, Jimmy A.; Webb, Natalie A.; Barret, Didier; Remillard, Ronald A.

    2013-12-01

    We report the discovery of a new ultraluminous X-ray source (ULX) 2XMM J125048.6+410743 within the spiral galaxy M94. The source has been observed by ROSAT, Chandra, and XMM-Newton on several occasions, exhibiting as a highly variable persistent source or a recurrent transient with a flux variation factor of gsim100, a high duty cycle (at least ~70%), and a peak luminosity of L X ~ 2 × 1039 erg s-1 (0.2-10 keV, absorbed). In the brightest observation, the source is similar to typical low-luminosity ULXs, with the spectrum showing a high-energy cutoff but harder than that from a standard accretion disk. There are also sporadical short dips, accompanied by spectral softening. In a fainter observation with L X ~ 3.6 × 1038 erg s-1, the source appears softer and is probably in the thermal state seen in Galactic black hole X-ray binaries (BHBs). In an even fainter observation (L X ~ 9 × 1037 erg s-1), the spectrum is harder again, and the source might be in the steep-power-law state or the hard state of BHBs. In this observation, the light curve might exhibit ~7 hr (quasi-)periodic large modulations over two cycles. The source also has a possible point-like optical counterpart from Hubble Space Telescope images. In terms of the colors and the luminosity, the counterpart is probably a G8 supergiant or a compact red globular cluster containing ~2 × 105 K dwarfs, with some possible weak UV excess that might be ascribed to accretion activity. Thus, our source is a candidate stellar-mass BHB with a supergiant companion or with a dwarf companion residing in a globular cluster. Our study supports that some low-luminosity ULXs are supercritically accreting stellar-mass BHBs.

  1. The stratigraphy of the Steep Rock Group, N.W. Ontario, with evidence of a major unconformity

    NASA Technical Reports Server (NTRS)

    Wilks, M. E.; Nisbet, E. G.

    1986-01-01

    The Steep Rock Group is exposed 6 km north of Atikokan, 200 km west of Thunder Bay. It is situated on the southern margin of the Wabigoon Belt of the Archaean Superior Province, N. W. Ontario. Reinvestigation of the geology of the Group has shown that the Group lies unconformably on the Tonalite Complex to the east. This unconformity has been previously suspected, from regional and ine mapping but no conclusive outcrop evidence for its existence has as yet been published. The strike of the group, comprised of Basal Conglomerate, Carbonate Member, Ore Zone and Ashrock is generally north-northwest dipping steeply to the southwest. Of the 7 contacts between the Steep Rock Group and the Tonalite Complex, 3 expose the unconformity (The Headland, S. Roberts Pit, Trueman Point), and 4 are faulted. These three outcrops demonstrate unequivocally that the Steep Rock group was laid down unconformably on the underlying Tonalite Complex, which is circa 3 Ga old.

  2. Effects of alternative steeping methods on composition, antioxidant property and colour of green, black and oolong tea infusions.

    PubMed

    Lantano, Claudia; Rinaldi, Massimiliano; Cavazza, Antonella; Barbanti, Davide; Corradini, Claudio

    2015-12-01

    Cold water steeping is reported to maximise tea health benefits, but requires long infusion time. In this work, the employment of a brief hot infusion step followed by ice addition was evaluated. The comparison of this innovative method with hot and cold steeping was investigated on green, black and oolong teas. Catechins, xanthines and gallic acid content, antioxidant power, total phenolics and colour analysis were evaluated. Hot infusion shown rapid extractive power, but relevant compound degradation. On the contrary, cold infusion extracted higher level of healthy molecules with slow kinetic. The innovative method achieved in short time similar properties of cold infusion in terms of antioxidant power. As for bioactive compounds, such as gallic acid and epigallocatechin gallate, highest values, about double than in hot infusion, were recorded for green and black teas. This steeping method may represent an alternative approach for industrial beverage preparation.

  3. When what we need influences what we see: choice of energetic replenishment is linked with perceived steepness.

    PubMed

    Taylor-Covill, Guy A H; Eves, Frank F

    2014-06-01

    The apparent steepness of the locomotor challenge presented by hills and staircases is overestimated in explicit awareness. Experimental evidence suggests the visual system may rescale our conscious experience of steepness in line with available energy resources. Skeptics of this "embodied" view argue that such findings reflect experimental demand. This article tested whether perceived steepness was related to resource choices in the built environment. Travelers in a station estimated the slant angle of a 6.45 m staircase (23.4°) either before (N = 302) or after (N = 109) choosing from a selection of consumable items containing differing levels of energetic resources. Participants unknowingly allocated themselves to a quasi-experimental group based on the energetic resources provided by the item they chose. Consistent with a resource based model, individuals that chose items with a greater energy density, or more rapidly available energy, estimated the staircase as steeper than those opting for items that provided less energetic resources.

  4. GPS/CSS radio sources and their relation to other AGN

    NASA Astrophysics Data System (ADS)

    Sadler, E. M.

    2016-02-01

    We are entering a new era of sensitive, large-area and multi-frequency radio surveys that will allow us to identify Gigahertz-Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) radio sources over a wide range in radio luminosity and study them within the context of the overall radio-source populations to which they belong. ``Classical'' GPS/CSS objects are extremely luminous radio sources with a compact double morphology, commonly thought to represent the earliest stages in the life cycle of powerful radio galaxies (e.g. O'Dea 1998). It is now becoming easier to identify GPS/CSS candidates with much lower radio luminosity - particularly in the nearby Universe. These less powerful objects, with typical 1.4 GHz radio luminosities of 1023 to 1025 W Hz-1, include peaked-spectrum radio sources with a core-jet morphology on parsec scales as well as high-frequency GPS-like peaked components embedded within lower-frequency extended emission. In the latter case, the presence of a young GPS component may not be evident from low-frequency data alone. Many radio galaxies in the local Universe have a compact (FR-0) morphology, and appear to lack extended radio emission on kiloparsec scales. The relationship of these FR-0 objects to the classical GPS/CSS radio sources remains unclear - some of them may represent short-lived episodes of AGN activity that will not lead to an extended FR-1 or FR-2 radio galaxy. Future wide-band radio surveys will shed more light on this - such surveys should ideally be coordinated to cover the full frequency range from 100 MHz to 100 GHz in order to sample all stages of GPS/CSS evolution in an unbiased way.

  5. Evaluation of meat, fruit and vegetables from retail stores in five United Kingdom regions as sources of extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant Escherichia coli.

    PubMed

    Randall, L P; Lodge, M P; Elviss, N C; Lemma, F L; Hopkins, K L; Teale, C J; Woodford, N

    2017-01-16

    We determined the prevalence and types of extended-spectrum β-lactamase (ESBL)-producing and carbapenem-resistant Escherichia coli in raw retail beef, chicken, pork, fruit and vegetables in five UK regions in 2013-14. Raw meat (n=397), and fruit and vegetable samples (n=400) were purchased from retail stores in London, East Anglia, North West England, Scotland and Wales. Samples were tested for the presence of ESBL-producing E. coli by plating enriched samples on CHROMagar CTX and CHROMagar ESBL, for AmpC-type E. coli by plating on "CHROMagar FOX" (CHROMagar ECC+16mg/L cefoxitin), and for carbapenem-resistant E. coli by plating on CHROMagar KPC. Additionally, pre-enrichment counts were performed on the above agars, and on CHROMagar ECC. Isolates of interest were characterised by MALDI-ToF to confirm identification, by PCR for blaCIT,blaCTX-M,blaOXA, blaSHV and blaTEM genes; ESBL or blaCIT genes were sequenced. Only 1.9% and 2.5% of beef and pork samples, respectively were positive for ESBL-producing E. coli after enrichment compared with 65.4% of chicken samples. 85.6% positive samples from chicken meat carried blaCTX-M-1; blaCTX-M-15 was not detected. None of the fruits or vegetables yielded ESBL-producing E. coli and none of the meat, fruit or vegetable samples yielded carbapenem-resistant E. coli. Retail chicken was more frequently a source of ESBL-producing E. coli than were beef, pork, fruit or vegetables. None of the foodstuffs yielded E. coli with CTX-M-15 ESBL, which dominates in human clinical isolates in the UK, and none yielded carbapenem-resistant E. coli.

  6. Properties of flat-spectrum radio-loud narrow-line Seyfert 1 galaxies

    NASA Astrophysics Data System (ADS)

    Foschini, L.; Berton, M.; Caccianiga, A.; Ciroi, S.; Cracco, V.; Peterson, B. M.; Angelakis, E.; Braito, V.; Fuhrmann, L.; Gallo, L.; Grupe, D.; Järvelä, E.; Kaufmann, S.; Komossa, S.; Kovalev, Y. Y.; Lähteenmäki, A.; Lisakov, M. M.; Lister, M. L.; Mathur, S.; Richards, J. L.; Romano, P.; Sievers, A.; Tagliaferri, G.; Tammi, J.; Tibolla, O.; Tornikoski, M.; Vercellone, S.; La Mura, G.; Maraschi, L.; Rafanelli, P.

    2015-03-01

    We have conducted a multiwavelength survey of 42 radio loud narrow-1ine Seyfert 1 galaxies (RLNLS1s), selected by searching among all the known sources of this type and omitting those with steep radio spectra. We analyse data from radio frequencies to X-rays, and supplement these with information available from online catalogues and the literature in order to cover the full electromagnetic spectrum. This is the largest known multiwavelength survey for this type of source. We detected 90% of the sources in X-rays and found 17% at γ rays. Extreme variability at high energies was also found, down to timescales as short as hours. In some sources, dramatic spectral and flux changes suggest interplay between a relativistic jet and the accretion disk. The estimated masses of the central black holes are in the range ~106-8 M⊙, lower than those of blazars, while the accretion luminosities span a range from ~0.01 to ~0.49 times the Eddington limit, with an outlier at 0.003, similar to those of quasars. The distribution of the calculated jet power spans a range from ~1042.6 to ~1045.6 erg s-1, generally lower than quasars and BL Lac objects, but partially overlapping with the latter. Once normalised by the mass of the central black holes, the jet power of the three types of active galactic nuclei are consistent with each other, indicating that the jets are similar and the observational differences are due to scaling factors. Despite the observational differences, the central engine of RLNLS1s is apparently quite similar to that of blazars. The historical difficulties in finding radio-loud narrow-line Seyfert 1 galaxies might be due to their low power and to intermittent jetactivity. Tables 4-9 and Figs. 8-13 are available in electronic form at http://www.aanda.org

  7. Film dosimetry calibration method for pulsed-dose-rate brachytherapy with an 192Ir source.

    PubMed

    Schwob, Nathan; Orion, Itzhak

    2007-05-01

    192Ir sources have been widely used in clinical brachytherapy. An important challenge is to perform dosimetric measurements close to the source despite the steep dose gradient. The common, inexpensive silver halide film is a classic two-dimensional integrator dosimeter and would be an attractive solution for these dose measurements. The main disadvantage of film dosimetry is the film response to the low-energy photon. Since the photon energy spectrum is known to vary with depth, the sensitometric curves are expected to be dependent on depth. The purpose of this study is to suggest a correction method for silver halide film dosimetry that overcomes the response changes at different depths. Sensitometric curves have been obtained at different depths with verification film near a 1 Ci 192Ir pulsed-dose-rate source. The depth dependence of the film response was observed and a correction function was established. The suitability of the method was tested through measurement of the radial dose profile and radial dose function. The results were compared to Monte Carlo-simulated values according to the TG43 formalism. Monte Carlo simulations were performed separately for the beta and gamma source emissions, using the EGS4 code system, including the low-energy photon and electron transport optimization procedures. The beta source emission simulation showed that the beta dose contribution could be neglected and therefore the film-depth dependence could not be attributed to this part of the source radioactivity. The gamma source emission simulations included photon-spectra collection at several depths. The results showed a depth-dependent softening of the photon spectrum that can explain the film-energy dependence.

  8. New approaches to inferences for steep-sided domes on Venus

    NASA Astrophysics Data System (ADS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Stephen M.; Stofan, Ellen R.

    2016-06-01

    New mathematical approaches for the relaxation and emplacement of viscous lava domes are presented and applied to steep-sided domes on Venus. A similarity solution approach is applied to the governing equation for fluid flow in a cylindrical geometry for two distinct scenarios. In the first scenario, dome relaxation is explored assuming a constant volume of fluid (i.e. lava) has been rapidly emplaced onto the surface. Cooling of lava is represented by a time-variable viscosity and singularities inherent in previous models for dome relaxation have been eliminated. At the onset of relaxation, bulk dynamic viscosities lie in the range between 1010-1016 Pa s, consistent with basaltic-andesite to rhyolitic compositions. Plausible relaxation times range from 5 to 5000 years, depending on initial lava viscosity. The first scenario, however, is only valid during the final stages of dome relaxation and does not consider the time taken for lava to be extruded onto the surface. In the second scenario, emplacement and growth of a steep-sided dome is considered when the volume of lava on the surface increases over time (i.e. time-variable volume approach). The volumetric flowrate may depend on an arbitrary power of the dome thickness, thus embracing Newtonian as well as other rheologies for describing terrestrial and planetary mass flows. The approach can be used to distinguish between basic flowrate models for fluid emplacement. The formalism results in radial expansion of a dome proportional to t1/2, consistent with the diffusive nature of the governing equation. The flow at the front is shown to thicken as the front advances for a constant rate of lava supply. Emplacement times are intimately correlated with the bulk rheology. Comparison of the theoretical profiles with the shape of a typical dome on Venus indicates that a Newtonian bulk rheology is most appropriate, consistent with prior studies. However, results here suggest a bulk dynamic viscosity of 1012-1013 Pa s and

  9. Tracing bed load sediment using PIT tags in a steep headwater channel.

    NASA Astrophysics Data System (ADS)

    Kubo, Y.; Hiraoka, M.; Gomi, T.; Nidaira, K.; Uchiyama, Y.

    2015-12-01

    Bed load transport in steep headwater channels is complex because of the particle size distribution, topography, channel roughness, and sediment supply from adjacent hillslope. We monitored movement bed load sediment using PIT tags in a steep headwater channel segments. Study area is located in 7.0ha Oobora-sawa observatory from 50km west of Tokyo metropolitan. Annual precipitation is 3000mm and mean temperature is 10°. Annual bed load sediment yields in the study catchment was from 6.5 to 7.6 t/ha/yr. Mean channel gradient is 24° with 0.5m low flow width. The channel is consisted by 0.2 to 1.6m interval of step-pool sequences. Based on pebble count method, D10, D50 and D90 of channel substrate were 8, 28 and 206mm respectively. We deployed 134 bed load tracers with five classes of diameter ranges (Class1:17.7, Class2:24.8, Class3:35.8, Class4:54.1 and Class5:83.8mm). Selected tracers represented from D20 to D77 of channel bed substrates. PIT tags (diameter 2mm, length 9mm and weight 0.1g) were placed into the particles by drilling and refilled with non-corrosive epoxy. We investigated the movement of bed load tracers every major storm event since February 2015. Channel morphology was measured using photographic survey and topographic model was developed using software of Surface from motion (PhotoScan). Mean bed load movement in the 5 storm event with 438 mm total and 33 mm maximum intensity was 168 mm. Then 51 mm of bed load movement occurred in 43 mm total and 16 mm intensity of rainfall. Recurrence interval of the two storm event was 1 and 4 year respectively. Receivable rates of bed load tracers was 70 and 74 % in the two events. Mobilized bed load (7 to 18%) deposited at cascade, pool and riffle, and among step clusters. Mobilized bed load tracers is rather random and we do not find any patterns for particle size for the movement and distance. Our field monitoring showed that bed load tracers were not mobilized for storm events with 10.5mm/h intensity of

  10. SYNTH: A spectrum synthesizer

    NASA Astrophysics Data System (ADS)

    Hensley, W. K.; McKinnon, A. D.; Miley, H. S.; Panisko, M. E.; Savard, R. M.

    1993-10-01

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma ray spectroscopy experiments. The code, dubbed SYNTH, allows a user to specify physical characteristics of a gamma ray source, the quantity of the nuclides producing the radiation, the source-to-detector distance and the presence of absorbers, the type and size of the detector, and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function versus energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers. It is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been compared carefully to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. Examples of the use of SYNTH and several spectral results are presented.

  11. Spatial and temporal variations in the effects of soil depth and topographic wetness index of bedrock topography on subsurface saturation generation in a steep natural forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Liang, Wei-Li; Chan, Meng-Chun

    2017-03-01

    Subsurface saturation near the bedrock surface is an important source of runoff generation and deeper bedrock recharge. While many studies have reported the generation patterns of subsurface saturation on valley side slopes or unchanneled catchments, studies focusing on the relationship between bedrock topography and subsurface saturation dynamics in a headwater catchment are still rare. This study therefore analyzed the effects of bedrock topographic features on subsurface saturation generation based on a dataset of pore water pressure (ψ) observations at the soil-bedrock interface and the spatial distributions of soil depth and the topographic wetness index (TWI) of bedrock topography in a steep natural forested headwater catchment. Temporal variations in the mean and standard deviation of ψ were lower at the perennially saturated points but higher at the ephemerally saturated points. The expansion patterns of subsurface saturation during storm events could be classified into four stages: fragmentary and unconnected distributions, both downward and upward expansions, interconnection from upslope to downslope, and disappearance from the middle slope. When saturation was interconnected, 41% of accumulated rainfall contributed to increases of subsurface saturation with a highly linear relationship. Soil depth correlated negatively with the increase in ψ at all points and at ephemerally saturated points. These negative correlations occurred frequently after the generation of new saturation, and remained for a short period around the early peaks of rainfall when the mean of ψ increased sharply. TWI correlated positively with ψ and ψ ⩾ 0 among all points but not in the subsets of perennially or ephemerally saturated points. The positive correlations became more significant after generation of new saturation. Overall, this study demonstrates that the effects of soil depth and TWI on subsurface saturation vary with space and time in a steep natural forested

  12. Adaptation to a steep environmental gradient and an associated barrier to gene exchange in Littorina saxatilis.

    PubMed

    Grahame, John W; Wilding, Craig S; Butlin, Roger K

    2006-02-01

    Steep environmental gradients offer important opportunities to study the interaction between natural selection and gene flow. Allele frequency clines are expected to form at loci under selection, but unlinked neutral alleles may pass easily across these clines unless a generalized barrier evolves. Here we consider the distribution of forms of the intertidal gastropod Littorina saxatilis, analyzing shell shape and amplified fragment length polymorphism (AFLP) loci on two rocky shores in Britain. On the basis of previous work, the AFLP loci were divided into differentiated and undifferentiated groups. On both shores, we have shown a sharp cline in allele frequencies between the two morphs for differentiated AFLP loci. This is coincident with a habitat transition on the shore where the two habitats (cliff and boulder field) are immediately contiguous. The allele frequency clines coincide with a cline in shell morphology. In the middle of the cline, linkage disequilibrium for the differentiated loci rises in accordance with expectation. The clines are extremely narrow relative to dispersal, probably as a result of both strong selection and habitat choice. An increase in F(ST) for undifferentiated AFLPs between morphs, relative to within-morph comparisons, is consistent with there being a general barrier to gene flow across the contact zone. These features are consistent either with an episode of allopatric divergence followed by secondary contact or with primary, nonallopatric divergence. Further data will be needed to distinguish between these alternatives.

  13. Biosurfactant production by Bacillus subtilis using corn steep liquor as culture medium

    PubMed Central

    Gudiña, Eduardo J.; Fernandes, Elisabete C.; Rodrigues, Ana I.; Teixeira, José A.; Rodrigues, Lígia R.

    2015-01-01

    In this work, biosurfactant production by Bacillus subtilis #573 was evaluated using corn steep liquor (CSL) as culture medium. The best results were obtained in a culture medium consisting of 10% (v/v) of CSL, with a biosurfactant production of about 1.3 g/l. To the best of our knowledge, this is the first report describing biosurfactant production by B. subtilis using CSL as culture medium. Subsequently, the effect of different metals (iron, manganese, and magnesium) on biosurfactant production was evaluated using the medium CSL 10%. It was found that for all the metals tested, the biosurfactant production was increased (up to 4.1, 4.4, and 3.5 g/l for iron, manganese, and magnesium, respectively). When the culture medium was supplemented with the optimum concentration of the three metals simultaneously, the biosurfactant production was increased up to 4.8 g/l. Furthermore, the biosurfactant exhibited a good performance in oil recovery assays when compared with chemical surfactants, which suggests its possible application in microbial enhanced oil recovery or bioremediation. PMID:25705209

  14. Steep-Slope Assembly Testing of Clay and Concrete Tile With and Without Cool Pigmented Colors

    SciTech Connect

    Miller, William A

    2005-11-01

    Cool color pigments and sub-tile venting of clay and concrete tile roofs significantly impact the heat flow crossing the roof deck of a steep-slope roof. Field measures for the tile roofs revealed a 70% drop in the peak heat flow crossing the deck as compared to a direct-nailed asphalt shingle roof. The Tile Roofing Institute (TRI) and its affiliate members are keenly interested in documenting the magnitude of the drop for obtaining solar reflectance credits with state and federal "cool roof" building efficiency standards. Tile roofs are direct-nailed or are attached to a deck with batten or batten and counter-batten construction. S-Misson clay and concrete tile roofs, a medium-profile concrete tile roof, and a flat slate tile roof were installed on fully nstrumented attic test assemblies. Temperature measures of the roof, deck, attic, and ceiling, heat flows, solar reflectance, thermal emittance, and the ambient weather were recorded for each of the tile roofs and also on an adjacent attic cavity covered with a conventional pigmented and directnailed asphalt shingle roof. ORNL measured the tile's underside temperature and the bulk air temperature and heat flows just underneath the tile for batten and counter-batten tile systems and compared the results to the conventional asphalt shingle.

  15. Hydrologic Effects of Clearcutting and Wildfire on Steep Granitic Slopes in Idaho

    NASA Astrophysics Data System (ADS)

    Megahan, Walter F.

    1983-06-01

    Many of the environmental impacts of logging and wildfire are caused by changes in the hydrologic response of slopes after disturbances. This study was conducted to evaluate changes in inflow, storage, and outflow for 3-year periods before and after clearcut logging and wildfire on two steep, granitic microwatersheds in Idaho. Clearcutting alone and clearcutting plus wildfire increased annual peak snow water equivalent and snowmelt rates an average of 41% and 30%, respectively. The greater volume and rate of snowmelt caused respective increases in the peak piezometric rise and in total piezometric storage, amounting to 47% and 27%. Accordingly, the total volume of subsurface flow intercepted by the roadcut was increased 96% and was accompanied by 27% greater peak flow rates. None of the above responses were detectable on an adjacent watershed that was burned by wildfire alone. Evapotranspiration was reduced on both watersheds after clearcutting or wildfire, as indicated by increases in the unsaturated soil water content at the end of the growing season amounting to 44 and 72%, respectively. Accelerated mass erosion on clearcut slopes, and accelerated surface and mass erosion on roads and in channels below roads, can result from such changes.

  16. Evaluation of two cockpit display concepts for civil tiltrotor instrument operations on steep approaches

    NASA Technical Reports Server (NTRS)

    Decker, William A.; Bray, Richard S.; Simmons, Rickey C.; Tucker, George E.

    1993-01-01

    A piloted simulation experiment was conducted using the NASA Ames Research Center Vertical Motion Simulator to evaluate two cockpit display formats designed for manual control on steep instrument approaches for a civil transport tiltrotor aircraft. The first display included a four-cue (pitch, roll, power lever position, and nacelle angle movement prompt) flight director. The second display format provided instantaneous flight path angle information together with other symbols for terminal area guidance. Pilots evaluated these display formats for an instrument approach task which required a level flight conversion from airplane-mode flight to helicopter-mode flight while decelerating to the nominal approach airspeed. Pilots tracked glide slopes of 6, 9, 15 and 25 degrees, terminating in a hover for a vertical landing on a 150 feet square vertipad. Approaches were conducted with low visibility and ceilings and with crosswinds and turbulence, with all aircraft systems functioning normally and were carried through to a landing. Desired approach and tracking performance was achieved with generally satisfactory handling qualities using either display format on glide slopes up through 15 degrees. Evaluations with both display formats for a 25 degree glide slope revealed serious problems with glide slope tracking at low airspeeds in crosswinds and the loss of the intended landing spot from the cockpit field of view.

  17. The effect of surface cover on infiltration rate in steep forest plantations

    NASA Astrophysics Data System (ADS)

    Hiraoka, M.; Onda, Y.; Kato, H.; Ito, S.; Mizugaki, S.

    2007-12-01

    The Japanese cypress (Hinoki; Chamaecyparis obtusa) is a major commercial tree species in Japan, and without thinning of high-density stands, canopy closure prevents development of understory vegetation. Therefore there is a concern for overlandflow and sediment yield due to infiltration rate lowering from steep hillslopes of Japanese cypress plantation. We developed a light-weight rainfall simulator based on the design of Meyer and Harmon (1979). A flat fan Veejet 80150 spraying nozzle (Spraying systems Co., USA) is mounted on the manifold at 2.13 m high from the plot surface. The nozzle oscillates so that the spray fans swept across the targeting 1m x 1m plot. The Veejet 80150 spraying nozzle produces large raindrops larger than 2 mm in diameter, and can simulate the high raindrop kinetic energy of natural storm. A targeted rainfall rate is 180 mm/h. Total 25 sprinkling experiments have been conducted on 35-degree hillslopes with varying surface cover. We obtained the minimum infiltration rate of 14 mm/h where the surface cover is very little. The infiltration rates were plotted against the total understory vegetation and dry weight of total surface cover including litter. The infiltration rate increased with the increasing total surface cover, and higher regression coefficient is obtained for the case of the total surface cover. These results will contribute to the future modeling studies of overlandflow occurrences for the catchment scales.

  18. Time series modeling of soil moisture dynamics on a steep mountainous hillside

    NASA Astrophysics Data System (ADS)

    Kim, Sanghyun

    2016-05-01

    The response of soil moisture to rainfall events along hillslope transects is an important hydrologic process and a critical component of interactions between soil vegetation and the atmosphere. In this context, the research described in this article addresses the spatial distribution of soil moisture as a function of topography. In order to characterize the temporal variation in soil moisture on a steep mountainous hillside, a transfer function, including a model for noise, was introduced. Soil moisture time series with similar rainfall amounts, but different wetness gradients were measured in the spring and fall. Water flux near the soil moisture sensors was modeled and mathematical expressions were developed to provide a basis for input-output modeling of rainfall and soil moisture using hydrological processes such as infiltration, exfiltration and downslope lateral flow. The characteristics of soil moisture response can be expressed in terms of model structure. A seasonal comparison of models reveals differences in soil moisture response to rainfall, possibly associated with eco-hydrological process and evapotranspiration. Modeling results along the hillslope indicate that the spatial structure of the soil moisture response patterns mainly appears in deeper layers. Similarities between topographic attributes and stochastic model structures are spatially organized. The impact of temporal and spatial discretization scales on parameter expression is addressed in the context of modeling results that link rainfall events and soil moisture.

  19. Gravitational spreading of steep-sided ridges ("sackung") in Western United States

    USGS Publications Warehouse

    Radbruch-Hall, D. H.; Varnes, D.J.; Savage, W.Z.

    1976-01-01

    Large-scale gravitational spreading and movement along fractures of steep-sided ridges in the mountainous areas of the western United States are characterized by linear fissures, trenches, and uphill-facing scarps on tops and sides of ridges. Spreading appears to take place by movement along disconnected planes and/or by slow plastic deformation of a rock mass. In some places, valleyward squeezing out of weak shales overlain by rigid rocks causes extensional fracturing and outward movement of the rigid layers, as illustrated by extension of two laccoliths overlying Mancos Shale, one at Dolores Peak and another at Crested Butte in western Colorado. Gravitational forces acting on a ridge of more homogeneous material causes tensional spreading of the ridge parallel to its long axis, for example in fractured granitic rock north of Mt. Massive in central Colorado, where a survey course has been established to monitor the movement. Recognition and understanding of these large-scale gravitational features and the mechanism that causes them are pertinent to site selection and design of engineering structures in high mountains. If fractures extend to considerable depth and if movement is continuing, engineering structures in valleys or tunnels through the spreading ridges could be damaged. ?? 1976 International Association of Engineering Geology.

  20. B-737 flight test of curved-path and steep-angle approaches using MLS guidance

    NASA Technical Reports Server (NTRS)

    Branstetter, J. R.; White, W. F.

    1989-01-01

    A series of flight tests were conducted to collect data for jet transport aircraft flying curved-path and steep-angle approaches using Microwave Landing System (MLS) guidance. During the test, 432 approaches comprising seven different curved-paths and four glidepath angles varying from 3 to 4 degrees were flown in NASA Langley's Boeing 737 aircraft (Transport Systems Research Vehicle) using an MLS ground station at the NASA Wallops Flight Facility. Subject pilots from Piedmont Airlines flew the approaches using conventional cockpit instrumentation (flight director and Horizontal Situation Indicator (HSI). The data collected will be used by FAA procedures specialists to develop standards and criteria for designing MLS terminal approach procedures (TERPS). The use of flight simulation techniques greatly aided the preliminary stages of approach development work and saved a significant amount of costly flight time. This report is intended to complement a data report to be issued by the FAA Office of Aviation Standards which will contain all detailed data analysis and statistics.

  1. Groundwater and surface water interaction in a basin surrounded by steep mountains, central Japan

    NASA Astrophysics Data System (ADS)

    Ikeda, Koichi; Tsujimura, Maki; Kaeriyama, Toshiaki; Nakano, Takanori

    2015-04-01

    Mountainous headwaters and lower stream alluvial plains are important as water recharge and discharge areas from the view point of groundwater flow system. Especially, groundwater and surface water interaction is one of the most important processes to understand the total groundwater flow system from the mountain to the alluvial plain. We performed tracer approach and hydrometric investigations in a basin with an area 948 square km surrounded by steep mountains with an altitude from 250m to 2060m, collected 258 groundwater samples and 112 surface water samples along four streams flowing in the basin. Also, Stable isotopes ratios of oxygen-18 (18O) and deuterium (D) and strontium (Sr) were determined on all water samples. The 18O and D show distinctive values for each sub-basin affected by different average recharge altitudes among four sub-basins. Also, Sr isotope ratio shows the same trend as 18O and D affected by different geological covers in the recharge areas among four sub-basins. The 18O, D and Sr isotope values of groundwater along some rivers in the middle stream region of the basin show close values as the rivers, and suggesting that direct recharge from the river to the shallow groundwater is predominant in that region. Also, a decreasing trend of discharge rate of the stream along the flow supports this idea of the groundwater and surface water interaction in the basin.

  2. Optimization of liquid-liquid extraction of biosurfactants from corn steep liquor.

    PubMed

    Vecino, X; Barbosa-Pereira, L; Devesa-Rey, R; Cruz, J M; Moldes, A B

    2015-09-01

    In this work, the optimization of the operational conditions for the chloroform-based extraction of surface-active compounds from corn steep liquor (CSL) was carried out and the nutritional properties of the remnant aqueous phase (CSL-less biosurfactant) was evaluated as microbial fermentation medium. The optimal conditions to obtain biosurfactants from CSL were as follows: chloroform/CSL ratio 2 (v/v), 56 °C at extraction times >30 min. At the optima conditions, 100 % of biosurfactant extract can be obtained from CSL, obtaining 12.0 ± 0.5 g of biosurfactant extract/Kg of CSL. The critical micelle concentration (CMC) of the biosurfactant extract was 399.4 mg L(-1). This value is similar to the CMC of cetrimonium bromide (CTAB), a cationic surfactant used in the formulation of nanoparticles. The extraction of biosurfactant can be also carried out at room temperature although in this case, the extraction yield decreased about 15 %. The extraction of surface-active compounds from agroindustrial streams can suppose important advances for the bio-based surfactants industry. Biosurfactants obtained in this work are not only more eco-friendly than chemical detergents but also can be cost competitive with its chemical counterparts. Furthermore, after the extraction of surface-active compounds, CSL-less biosurfactant was found to be suitable as nutritional supplement for lactic acid bacteria, maintaining its nutritional properties in comparison with regular CSL.

  3. The Bolund Experiment, Part I: Flow Over a Steep, Three-Dimensional Hill

    NASA Astrophysics Data System (ADS)

    Berg, J.; Mann, J.; Bechmann, A.; Courtney, M. S.; Jørgensen, H. E.

    2011-11-01

    We present an analysis of data from a measurement campaign performed at the Bolund peninsula in Denmark in the winter of 2007-2008. Bolund is a small isolated hill exhibiting a significantly steep escarpment in the main wind direction. The physical shape of Bolund represents, in a scaled-down form, a typical wind turbine site in complex terrain. Because of its small size the effect of atmospheric stratification can be neglected, which makes the Bolund experiment ideal for the validation of neutral flow models and hence model scenarios most relevant to wind energy. We have carefully investigated the upstream conditions. With a 7-km fetch over water, the incoming flow is characterized as flow over flat terrain with a local roughness height based on the surface momentum flux. The nearly perfect upstream conditions are important in forming a meaningful quantitative description of the flow over the Bolund hill. Depending on the wind direction, we find a maximum speed-up of 30% at the hill top accompanied by a maximum 300% enhancement of turbulence intensity. A closer inspection reveals transient behaviour with recirculation zones. From the wind energy context, this implies that the best site for erecting a turbine based on resource constraints unfortunately also imposes a penalty of high dynamic loads. On the lee side of Bolund, recirculation occurs with the turbulence intensity remaining significantly enhanced even at one hill length downstream. Its transient behaviour and many recirculation zones place Bolund in a category in which the linear flow theory is not applicable.

  4. Adapting Tilt Corrections and the Governing Flow Equations for Steep, Fully Three-Dimensional, Mountainous Terrain

    NASA Astrophysics Data System (ADS)

    Oldroyd, Holly J.; Pardyjak, Eric R.; Huwald, Hendrik; Parlange, Marc B.

    2016-06-01

    In recent studies of atmospheric turbulent surface exchange in complex terrain, questions arise concerning velocity-sensor tilt corrections and the governing flow equations for coordinate systems aligned with steep slopes. The standard planar-fit method, a popular tilt-correction technique, must be modified when applied to complex mountainous terrain. The ramifications of these adaptations have not previously been fully explored. Here, we carefully evaluate the impacts of the selection of sector size (the range of flow angles admitted for analysis) and planar-fit averaging time. We offer a methodology for determining an optimized sector-wise planar fit (SPF), and evaluate the sensitivity of momentum fluxes to varying these SPF input parameters. Additionally, we clarify discrepancies in the governing flow equations for slope-aligned coordinate systems that arise in the buoyancy terms due to the gravitational vector no longer acting along a coordinate axis. New adaptions to the momentum equations and turbulence kinetic energy budget equation allow for the proper treatment of the buoyancy terms for purely upslope or downslope flows, and for slope flows having a cross-slope component. Field data show that new terms in the slope-aligned forms of the governing flow equations can be significant and should not be omitted. Since the optimized SPF and the proper alignment of buoyancy terms in the governing flow equations both affect turbulent fluxes, these results hold implications for similarity theory or budget analyses for which accurate flux estimates are important.

  5. Identify bipolar spectrum disorders.

    PubMed

    Mynatt, Sarah; Cunningham, Patricia; Manning, J Sloan

    2002-06-01

    Patients with bipolar spectrum disorders commonly present with depressive symptoms to primary care clinicians. This article details bipolar spectrum disorder assessment, treatment, and treatment response. By intervening early in the course of depressive and hypomanic episodes, you can help decrease the morbidity and suffering associated with bipolar spectrum disorders.

  6. Contributions of human activities to suspended-sediment yield during storm events from a steep, small, tropical watershed, American Samoa

    NASA Astrophysics Data System (ADS)

    Messina, A. T.; Biggs, T. W.

    2014-12-01

    Anthropogenic watershed disturbance by agriculture, deforestation, roads, and urbanization can alter the timing, composition, and mass of sediment loads to adjacent coral reefs, causing enhanced sediment stress on corals near the outlets of impacted watersheds like Faga'alu, American Samoa. To quantify the increase in sediment loading to the adjacent priority coral reef experiencing sedimentation stress, suspended-sediment yield (SSY) from undisturbed and human-disturbed portions of a small, steep, tropical watershed was measured during baseflow and storm events of varying magnitude. Data on precipitation, discharge, turbidity, and suspended-sediment concentration (SSC) were collected over three field campaigns and continuous monitoring from January 2012 to March 2014, which included 88 storm events. A combination of paired- and nested-watershed study designs using sediment budget, disturbance ratio, and sediment rating curve methodologies was used to quantify the contribution of human-disturbed areas to total SSY. SSC during base- and stormflows was significantly higher downstream of an open-pit aggregate quarry, indicating the quarry is a key sediment source requiring sediment discharge mitigation. Comparison of event-wise SSY from the upper, undisturbed watershed, and the lower, human-disturbed watershed showed the Lower watershed accounted for more than 80% of total SSY on average, and human activities have increased total sediment loading to the coast by approximately 200%. Four storm characteristics were tested as predictors of event SSY using Pearson's and Spearman's correlation coefficients. Similar to mountainous watersheds in semi-arid and temperate watersheds, SSY from both the undisturbed and disturbed watersheds had the highest correlation with event maximum discharge, Qmax (Pearson's R=0.88 and 0.86 respectively), and were best fit by a power law relationship. The resulting model of event-SSY from Faga'alu is being incorporated as part of a larger

  7. The faint source population at 15.7 GHz - III. A high-frequency study of HERGs and LERGs

    NASA Astrophysics Data System (ADS)

    Whittam, I. H.; Riley, J. M.; Green, D. A.; Jarvis, M. J.

    2016-10-01

    A complete sample of 96 faint (S > 0.5 mJy) radio galaxies is selected from the Tenth Cambridge (10C) survey at 15.7 GHz. Optical spectra are used to classify 17 of the sources as high-excitation or low-excitation radio galaxies (HERGs and LERGs, respectively), for the remaining sources three other methods are used; these are optical compactness, X-ray observations and mid-infrared colour-colour diagrams. 32 sources are HERGs and 35 are LERGs while the remaining 29 sources could not be classified. We find that the 10C HERGs tend to have higher 15.7-GHz flux densities, flatter spectra, smaller linear sizes and be found at higher redshifts than the LERGs. This suggests that the 10C HERGs are more core dominated than the LERGs. Lower-frequency radio images, linear sizes and spectral indices are used to classify the sources according to their radio morphology; 18 are Fanaroff and Riley type I or II sources, a further 13 show some extended emission, and the remaining 65 sources are compact and are referred to as FR0 sources. The FR0 sources are sub-divided into compact, steep-spectrum sources (13 sources) or gigahertz-peaked spectrum sources (10 sources) with the remaining 42 in an unclassified class. FR0 sources are more dominant in the subset of sources with 15.7-GHz flux densities <1 mJy, consistent with the previous result that the fainter 10C sources have flatter radio spectra. The properties of the 10C sources are compared to the higher-flux density Australia Telescope 20 GHz (AT20G) survey. The 10C sources are found at similar redshifts to the AT20G sources but have lower luminosities. The nature of the high-frequency selected objects changes as flux density decreases; at high flux densities the objects are primarily quasars, while at low flux densities radio galaxies dominate.

  8. Storm runoff generation at a steep pre-alpine hillslope - transmissivity feedback or organic layer interflow?

    NASA Astrophysics Data System (ADS)

    Schneider, Philipp; Pool, Sandra; Strouhal, Ludek; Seibert, Jan

    2015-04-01

    This study investigated storm runoff generation processes of a pre-alpine hillslope prone to slide. The experimental pasture plot is located in the northern front range of the Swiss Alps on a 30° steep hillslope. A gleysol overlies weathered marlstone and conglomerate of subalpine molasse. We conducted sprinkling experiments on a subplot with variable rainfall intensities. During both experiments fluorescein line-tracer injections into the topsoil, and sodium chloride (NaCl) injections into the sprinkling water were used to monitor flow velocities in the soil. The observed flow velocities for fluorescein in the soil were 1.2 and 1.4 × 10-3 m s-1. The NaCl breakthrough occurred almost simultaneously in all monitored discharge levels (0.05, 0.25 and 1.0 m depth), indicating a high infiltration capacity and efficient lateral drainage of the soil. These initial observations suggested 'transmissivity feedback' (a form of subsurface stormflow described in Nordic catchments by Allan Rhode in 1987) as the dominant storm runoff generation process. However, excavation of dye-stained soil horizons from a brilliant blue tracer experiment completely changed our perceptions of the prevailing storm flow paths and its runoff generation mechanisms. The results highlighted the dominance of 'organic layer interflow', a form of shallow subsurface stormflow at the hillslope. The dye stained the entire topsoil horizon, vertical soil fractures, and macropores (mostly worm burrows) up to 0.5 m depth. Lateral drainage in the subsoil horizons or at the soil-bedrock interface was not observed; drainage was limited to the organic topsoil. The subsoil with its low permeability acted locally as a soil percolation and bedrock exfiltration barrier, producing significant lateral drainage in the organic topsoil and pronounced pore water pressure changes in the bedrock. Reference Rohde, A.: The origin of streamwater traced by Oxygen-18, 260 pp., Uppsala University., 1987.

  9. Infiltration and Runoff Measurements on Steep Burned Hillslopes Using a Rainfall Simulator with Variable Rain Intensities

    USGS Publications Warehouse

    Kinner, David A.; Moody, John A.

    2008-01-01

    Multiple rainfall intensities were used in rainfall-simulation experiments designed to investigate the infiltration and runoff from 1-square-meter plots on burned hillslopes covered by an ash layer of varying thickness. The 1-square-meter plots were on north- and south-facing hillslopes in an area burned by the Overland fire northwest of Boulder near Jamestown on the Front Range of Colorado. A single-nozzle, wide-angle, multi-intensity rain simulator was developed to investigate the infiltration and runoff on steep (30- to 40-percent gradient) burned hillslopes covered with ash. The simulated rainfall was evaluated for spatial variability, drop size, and kinetic energy. Fourteen rainfall simulations, at three intensities (about 20 millimeters per hour [mm/h], 35 mm/h, and 50 mm/h), were conducted on four plots. Measurements during and after the simulations included runoff, rainfall, suspended-sediment concentrations, surface ash layer thickness, soil moisture, soil grain size, soil lost on ignition, and plot topography. Runoff discharge reached a steady state within 7 to 26 minutes. Steady infiltration rates with the 50-mm/h application rainfall intensity approached 20?35 mm/h. If these rates are projected to rainfall application intensities used in many studies of burned area runoff production (about 80 mm/h), the steady discharge rates are on the lower end of measurements from other studies. Experiments using multiple rainfall intensities (three) suggest that runoff begins at rainfall intensities around 20 mm/h at the 1-square-meter scale, an observation consistent with a 10-mm/h rainfall intensity threshold needed for runoff initiation that has been reported in the literature.

  10. Seismic component of the STEEP project, Alaska: Results of the first field season

    NASA Astrophysics Data System (ADS)

    Hansen, R. A.; Estes, S.; Stachnik, J.; Lafevers, M.; Roush, J.; Sanches, R.; Fuerst, E.; Sandru, J.; Ruppert, N.; Pavlis, G.; Bauer, M.

    2005-12-01

    STEEP (SainT Elias Erosion/tectonics Project) is a five year, multi-disciplinary study that addresses evolution of the highest coastal mountain range on Earth - the St. Elias Mountains of southern Alaska and northwestern Canada. The overall goal of the project is to develop a comprehensive model for the St. Elias orogen that accounts for the interaction of regional plate tectonic processes, structural development, and rapid erosion. The seismic component of this project includes passive seismic experiment utilizing the IRIS PASSCAL Program instruments. The total project consists of 22 new, telemetered, digital broad band seismic stations, most accessible by helicopter only. There are 12 existing short period stations in the area. Eight new stations were installed in the coastal region in June 2005. Freewave IP radios provide the telemetry to the newly installed VSAT at the Bering Glacier camp site. The challenge was to find ice-free locations, on bedrock, large enough to install equipment and still have a helicopter landing zone nearby. The stations consist of Quanterra Q330 digitizers with baler, a STS-2 seismometer installed in a vault, a Freewave IP radio, a Scala 900 Mhz antenna, twenty 100 AH rechargeable batteries with a 2400AH backup Celair primary battery, and three solar panels mounted on hut. The acquired data is recorded in real time at the Alaska Earthquake Information Center located in Fairbanks and is incorporated into the standard data processing procedures. High quality data allows for more reliable automatic earthquake detections in the region with lower magnitude threshold. In addition to tectonic earthquakes, glacial events that occur within the vast ice fields of the region are also regularly detected. Broadband instruments complement regional broadband network for more reliable calculations of the regional moment tensors.

  11. Timing of deposition and failure of steep carbonate slopes, Tongue of the Ocean, Bahamas

    SciTech Connect

    Grammer, G.M.; Ginsburg, R.N. )

    1991-03-01

    Steep marginal slopes around the Tongue of the Ocean record deposition during the early rise of sea level following the last lowstand some 18,000-21,000 years B.P. Coarse-grained skeletal packstones and grainstones derived from the overlying escarpment were deposited on slopes of 35-45{degree} and rapidly cemented in place. Deposition by rockfall and grainflow processes resulted in a series of elongate lenses oriented parallel to the slope. These lenses are generally less than 0.5 m thick and pinch out downslope within tens of meters. Radiocarbon dating indicates that active deposition on the slopes ceased abruptly about 10,000 years ago as sea level rose above the escarpment and began to flood the top of Great Bahama Bank. Fine-grained, nonskeletal sands and muds derived from the platform are presently by passing these slopes resulting in a 'modern' example of a drowning unconformity. Although these slopes are no longer sites of active deposition, they are still influencing the ultimate record of slope sedimentation. Arcuate, concave-up cracks in the cemented slope indicate zones of weakness and possibly represent areas susceptible to slope failure. These cracks are a few centimeters wide and may extend for tens of meters across the slope. Post-depositional failure of the slope has been observed at several locations. These slide/slump scars are as much as 30 m across and may extend downslope for 70-80 m. Large blocks, some more than 10 m across, derived from failure of the relict slope have been transported for tens or hundreds of meters downslope. The release and transport of such blocks may be one mechanism by which turbidity currents are initiated in deeper slope environments.

  12. Low Rates of Weathering and Erosion in Wet, Steep, Tropical Highlands

    NASA Astrophysics Data System (ADS)

    von Blanckenburg, F.; Hewawasam, T.

    2003-12-01

    The Central Highlands of the island of Sri Lanka feature all the ingredients usually thought to promote high rates of weathering: crystalline rocks, warm climate, high rates of precipitation. Also the high relief (steep mountains of up to 2500m altitude) would potentially generate high rates of physical erosion, which in turn promotes weathering by providing fresh mineral surfaces. An analysis of the rates of total erosion, using cosmogenic nuclides, excluding the effects of anthropogenic perturbance [1], was performed on various parts of the landscape (bedrock, surface soil, river sediment). The results suggest that all parts of the Highlands erode at 5-15mm/ky only. Rates of chemical weathering, determined by analysing major cations in river water, further suggest that most of this denudation is chemical. These rates of erosion are amongst the lowest world-wide for any sloping area analysed to date with cosmogenic nuclides. No relationship between climate and erosion is apparent for these areas. For Sri Lanka, we suggest that rock weathering has been low for millions of years due to (a) development of a clay-rich surface layer protecting rocks from corrosive fluids; (b) thick vegetation inhibiting removal of this layer; and (c), most importantly, absence of recent tectonic activity that would rejuvenate the landscape and promote physical erosion. Therefore, climate does not appear to exert controls over rock weathering if active tectonic forcing is absent. 1 T. Hewawasam, F. von Blanckenburg, M. Schaller and W. Kubik, Increase of human over natural erosion rates in tropical highlands constrained by cosmogenic nuclides, Geology 31, 795-600, 2003.

  13. Monitoring of a steep rockfall area experiencing fast displacements in Kåfjord, Northern Norway

    NASA Astrophysics Data System (ADS)

    Dreiås Majala, Gudrun; Harald Blikra, Lars; Skrede, Ingrid; Kristensen, Lene

    2016-04-01

    An unstable rockfall area in Kåfjord, Northern Norway, was recognized during periodic monitoring campaigns in July and early September 2015. The LiSALab ground based Interferometric Synthethic Aperture Radar (GB InSAR) from Ellegi were used. A relatively sharply defined steep area of 1200 m2 (6.000 - 12.000 m3) was documented to be in movement. Norwegian Water Resources and Energy Directorate (NVE) was at this point performing mitigation work in terms of an embarkment within the rockfall run-out area. The monitoring system was reinstalled and adjusted to perform continuous monitoring with an early-warning aim. The section for rockslide management in NVE was responsible for the monitoring and the warning to the municipality and Police. The displacements increased from about 1 mm/day in July to 3 cm/day in mid September. People were evalcuated due to increased velocities the 16th of September. The displacements continued to increase in several stages, and with a distinct accelleration the 2nd of October. The velocity peaked in a short window to more than 200 cm/day, and it ended with a partly frontal and sideway collapse of the unstable area. However, large parts of the area stabilized again, and the run-out lengths from the small rockfalls were limited. The GB InSAR system operated exceptionally well during the event, and were able to follow continuously the displacements during the accelleration stage until collapse as the processing time window was frequently adjusted to the changes in velocity. We were also able to follow inidividual rockfalls from the images - primarily as the rockfall impact points on the slope below showed up clearly on the radar images. The area continued to stabilize due to falling temperatures, and the mitigation work were finished during the fall. The displacements seem to be correlated to the increasing temperatures in late summer and precipitation events.

  14. Steep Decline and Low Hydrocarbon Recovery in Fractured Shale: What and Why?

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Barber, T.; Gao, Z.; Gao, X.; Ewing, R. P.

    2014-12-01

    Since 2000, the technological advances of horizontal drilling and hydraulic fracturing in the United States have led to a dramatic increase in hydrocarbon (gas and oil) production from shale formations, changing the energy landscape in the US and worldwide. Since 2005, the surge in tight oil production from shale formations has provided tremendous optimism regarding future United States hydrocarbon production, unexpectedly becoming the fastest-growing frontier of unconventional resources. According to the Energy Information Administration's newly released report in 2014, US oil output from tight oil prospects will almost double from the 2012 level of 2.5 million barrels per day, to 4.8 by 2019. However, total gas recovery from the Barnett play was reported to be only12-30%, and the tight-oil recovery rate from shale formations is even lower at 5-10%. The main barrier to sustainable development of US shale, the pore structure of the nanopores storing and transporting hydrocarbons, has been quietly ignored. We have studied pore structure, edge-accessible porosity, and how wettability is associated with mineral and organic kerogen phases, from four complementary tests: vacuum saturation with vacuum-pulling on dry shale followed with tracer introduction, tracer diffusion into fluid-saturated shale, fluid and tracer imbibition into partially-saturated shale, and Wood's metal intrusion followed with SEM imaging and elemental mapping. The first three tests use tracer-bearing fluids (API brine or n-decane), with tracer distribution on shale mapped with micro-scale laser ablation-ICP-MS analyses. These innovative approaches indicate the limited accessibility (several millimeters from shale sample edge) and connectivity of nanopores in shales under atmospheric condition, which is linked to the steep initial (e.g., 1st year) decline and low overall recovery because of the limited connection of hydrocarbon molecules in the shale matrix to the stimulated fracture network.

  15. Effect of corn bran and steep inclusion in finishing diets on diet digestibility, cattle performance, and nutrient mass balance.

    PubMed

    Sayer, K M; Buckner, C D; Erickson, G E; Klopfenstein, T J; Macken, C N; Loy, T W

    2013-08-01

    One metabolism trial and 2 finishing trials were conducted to evaluate the effects of adding corn bran and steep liquor (steep) in replacement of dry-rolled corn (DRC) on diet digestibility, cattle performance, and nutrient mass balance in open feedlot pens. The metabolism trial (Exp. 1) used 8 ruminally cannulated heifers in a 4 × 4 Latin square design and the 2 finishing trials used 128 steer calves fed for 167 d (Exp. 2) and 256 yearling steers fed for 126 d (Exp. 3). Dietary treatments for all trials included a DRC-based control (CON), 30% corn bran (30/0), 30% corn bran plus 15% steep (30/15), and 45% corn bran plus 15% steep (45/15), in which by-products replaced DRC and molasses in the diet (DM basis). Diets were not isonitrogenous or isoenergetic. In the metabolism trial, feeding the by-product diets produced greater rumen pH (5.95) than CON (5.76; P < 0.01). Total tract DM and OM digestibility were greater for heifers fed CON than the by-product diets (P < 0.01). Dry matter and NDF ruminal disappearance (%/h) of corn bran were numerically less for cattle fed the CON diet than the by-product diets (2.36 vs. 2.84 and 0.72 vs. 1.66, respectively). In the performance trials, steers fed the by-product diets consumed more DM (P = 0.06) and G:F was either similar for all diets in Exp. 2 (P = 0.56) or less for cattle fed 30/0 than the other diets in Exp. 3 (P = 0.05). Percent N loss was reduced in Exp. 2 by including corn bran in diets compared with CON (P < 0.01). However, in Exp. 3, no differences in percent N loss were detected among treatments (P = 0.16), but more N was removed in the manure from pens where steers were fed by-products (P = 0.01). Although steep did not improve diet digestibility, it was beneficial in maintaining cattle performance in the feedlot studies. Feeding corn bran in combination with steep increased manure N removed and N in compost, but decreased percent N lost during the winter months only.

  16. The Divergence of Wear Propagation and Stress at Steep Acetabular Cup Positions Using Ceramic Heads and Sequentially Cross-Linked Polyethylene Liners.

    PubMed

    Zietz, Carmen; Fabry, Christian; Baum, Felix; Bader, Rainer; Kluess, Daniel

    2015-08-01

    The aim of the present wear simulator study was to assess the effect of steep acetabular cup positions on the wear propagation of highly cross-linked-PE (HX-PE) liners. Furthermore, a finite element analysis (FEA) was performed in order to calculate the stress within the HX-PE material in case of steep cup positions under physiological loadings. The higher stress in the HX-PE at a steep acetabular cup position did not result in increased wear in the present wear simulator study. The gravimetrical wear rates at normal (45°) and steep cup inclinations (75°) showed wear amounts of 3.15±0.27mg and 2.18±0.31mg per million cycles (p=0.028), respectively. However, FEA revealed clear increase in stress at the HX-PE liners with respect to steep cup positions.

  17. High-frequency excess in the radio continuum spectrum of the type-1 Seyfert galaxy NGC 985

    NASA Astrophysics Data System (ADS)

    Doi, Akihiro; Inoue, Yoshiyuki

    2016-08-01

    The Seyfert galaxy NGC 985 is known to show a high-frequency excess in its radio continuum spectrum at a milli-Jansky level on the basis of previous observations at 1.4-15 GHz; a steep spectrum at low frequencies (a spectral index, α = -1.10 ± 0.03) changes at ˜10 GHz into an inverted spectrum at higher frequencies (α = +0.86 ± 0.09). We conduct new observations at 15-43 GHz using the Very Large Array and at 100 GHz using the Nobeyama Millimeter Array. As a result, the high-frequency excess has been confirmed as continuing at even higher radio frequencies, up to 43 GHz. The non-detection at 100 GHz was not so strong a constraint, and therefore the spectral behavior above 43 GHz remains unclear. The astrometric position of the high-frequency excess component coincides with the optical position of the Seyfert nucleus and the low-frequency radio position to an accuracy of 0{^''.}1, corresponding to ˜80 pc; the radio source size is constrained to be <0{^''.}02, corresponding to <16 pc. We discuss the physical origin of the observed high-frequency excess component. Dust emission at the Rayleigh-Jeans regime, free-free emission from X-ray radiating high-temperature plasma, free-free emission from the ensemble of broad-line region clouds, or thermal synchrotron from hot accretion flow cannot be responsible for the observed radio flux. Compact jets under synchrotron self-absorption may be unlikely in terms of observed time scales. Alternatively, we cannot rule out the hypotheses of synchrotron jets free-free absorbed by a circumnuclear photo-ionized region, and self-absorbed nonthermal synchrotron from disk corona, as the origin of the high-frequency excess component.

  18. Ninth Spectrum of Bromine: Br IX

    NASA Astrophysics Data System (ADS)

    Joshi, Y. N.; van Kleef, Th A. M.

    1981-03-01

    The spectrum of bromine was photographed on a 6.60 m and a 10.7 m grazing incidence spectrograph in the region 300-90 Å. The source used was a triggered spark. The ninth spectrum of bromine was analysed on the basis of 3d9-3d84p transitions between 125-104 Å. Parametric level fitting calculations support the analysis. 44 lines are classified in this spectrum. Some Br VIII lines appearing in this region have been accurately measured.

  19. An extended steepness model for leg-size determination based on Dachsous/Fat trans-dimer system.

    PubMed

    Yoshida, Hiroshi; Bando, Tetsuya; Mito, Taro; Ohuchi, Hideyo; Noji, Sumihare

    2014-03-11

    What determines organ size has been a long-standing biological question. Lawrence et al. (2008) proposed the steepness hypothesis suggesting that the protocadherin Dachsous/Fat (Ds/Ft) system may provide some measure of dimension to the cells in relation to the gradient. In this paper we extended the model as a means of interpreting experimental results in cricket leg regeneration. We assumed that (1) Ds/Ft trans-heterodimers or trans-homodimers are redistributed during cell division, and (2) growth would cease when a differential of the dimer across each cell decreases to a certain threshold. We applied our model to simulate the results obtained by leg regeneration experiments in a cricket model. The results were qualitatively consistent with the experimental data obtained for cricket legs by RNA interference methodology. Using our extended steepness model, we provided a molecular-based explanation for leg size determination even in intercalary regeneration and for organ size determination.

  20. An extended steepness model for leg-size determination based on Dachsous/Fat trans-dimer system

    PubMed Central

    Yoshida, Hiroshi; Bando, Tetsuya; Mito, Taro; Ohuchi, Hideyo; Noji, Sumihare

    2014-01-01

    What determines organ size has been a long-standing biological question. Lawrence et al. (2008) proposed the steepness hypothesis suggesting that the protocadherin Dachsous/Fat (Ds/Ft) system may provide some measure of dimension to the cells in relation to the gradient. In this paper we extended the model as a means of interpreting experimental results in cricket leg regeneration. We assumed that (1) Ds/Ft trans-heterodimers or trans-homodimers are redistributed during cell division, and (2) growth would cease when a differential of the dimer across each cell decreases to a certain threshold. We applied our model to simulate the results obtained by leg regeneration experiments in a cricket model. The results were qualitatively consistent with the experimental data obtained for cricket legs by RNA interference methodology. Using our extended steepness model, we provided a molecular-based explanation for leg size determination even in intercalary regeneration and for organ size determination. PMID:24613915

  1. The H I Kinematics of NGC 4013: A Steep and Radially Shallowing Extra-planar Rotational Lag

    NASA Astrophysics Data System (ADS)

    Zschaechner, Laura K.; Rand, Richard J.

    2015-08-01

    NGC 4013 is a distinctly warped galaxy with evidence of disk-halo activity. Through deep H i observations and modeling we confirm that the H i disk is thin (central exponential scale height with an upper limit of 4″ or 280 pc), but flaring. We detect a vertical gradient in rotation velocity (lag), which shallows radially from a value of -35{}-28+7 km s-1 kpc-1 at 1.‧4 (5.8 kpc), to a value of zero near R25 (11.2 kpc). Over much of this radial range, the lag is relatively steep. Both the steepness and the radial shallowing are consistent with recent determinations for a number of edge-ons, which have been difficult to explain. We briefly consider the lag measured in NGC 4013 in the context of this larger sample and theoretical models, further illuminating disk-halo flows.

  2. Spatial distribution of steep lunar craters may be linked to size-dependent orbital distribution of impactors

    NASA Astrophysics Data System (ADS)

    JeongAhn, Youngmin; Malhotra, Renu; Werner, Stephanie; Lee, Jui-Chi; Trang, David; Ip, Wing-Huen; Reyes-Ruiz, Mauricio

    2016-10-01

    The depth/diameter (d/D) ratio of simple lunar craters (D<15km) is known to be ~0.2 at the time of formation; larger complex craters (D>15km) have smaller d/D ratios. We examine the spatial distribution of high d/D ratio (>0.18) craters using LU60645GT catalogue (Salamunićcar et al. 2012). We select craters larger than 8km for which the census is known to be almost complete over the whole lunar surface. We find that the number density of steep craters in maria is significantly lower than in highlands, which may be explained by the age differences of the background surfaces. We also find that the spatial density of steep craters in the equatorial region is lower than in the polar region. On the contrary, higher cratering flux on the lunar equator has been claimed: from the numerical calculations with the orbital distribution of observed Earth Crossing Objects (ECOs) larger than 1km (Le Feuvre & Wieczorek 2008; Ito & Malhotra 2010) and from the distribution of steepest slopes at a 25m baseline (Kreslavsky & Head, 2016). In order to reconcile our findings with previous observations, we hypothesize that the cratering rate at low latitudes has been higher for meter to decameter size ECOs than for kilometer size objects since the Late Imbrian epoch; smaller objects have triggered more frequent mass wasting on the pre-existing large steep craters (D>8km, d/D>0.18) at low latitudes, thereby reducing the surviving number of steep craters. Our hypothesis is supported by the finding that the power-law slope in the H magnitude distribution for the low inclination ECOs (i<15 deg) is steeper than for the high inclination objects. Renu Malhotra acknowledges research support from NSF (grant AST-1312498).

  3. Chromosomal gain promotes formation of a steep RanGTP gradient that drives mitosis in aneuploid cells

    PubMed Central

    Hasegawa, Keisuke; Ryu, Sung Jin

    2013-01-01

    Many mitotic factors were shown to be activated by Ran guanosine triphosphatase. Previous studies in Xenopus laevis egg extracts and in highly proliferative cells showed that mitotic chromosomes were surrounded by steep Ran guanosine triphosphate (GTP) concentration gradients, indicating that RanGTP-activated factors promote spindle assembly around chromosomes. However, the mitotic role of Ran in normal differentiated cells is not known. In this paper, we show that although the steep mitotic RanGTP gradients were present in rapidly growing cell lines and were required for chromosome congression in mitotic HeLa cells, the gradients were strongly reduced in slow-growing primary cells, such as HFF-1 fibroblasts. The overexpression of RCC1, the guanine nucleotide exchange factor for Ran, induced steeper mitotic RanGTP gradients in HFF-1 cells, showing the critical role of RCC1 levels in the regulation of mitosis by Ran. Remarkably, in vitro fusion of HFF-1 cells produced cells with steep mitotic RanGTP gradients comparable to HeLa cells, indicating that chromosomal gain can promote mitosis in aneuploid cancer cells via Ran. PMID:23319601

  4. On the influence of high voltage slope steepness on breakdown and development of pulsed dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Höft, H.; Becker, M. M.; Loffhagen, D.; Kettlitz, M.

    2016-12-01

    The influence of the steepness of the applied high voltage (HV) waveform on the characteristics of pulsed dielectric barrier discharges (DBDs) is investigated using a single-filament arrangement with 1 mm gap in 0.1 vol% O2 in N2 at atmospheric pressure. The slope steepness was varied between 75 V ns-1 and 200 V ns-1. The discharge development was recorded with a combined iCCD and streak camera system accompanied by electrical measurements. The analysis was supported by time-dependent, spatially one-dimensional fluid model calculations. A steeper HV slope leads to a higher transferred charge and electrical energy per cycle. The DBD emission structure in the gap features a shorter ‘dark space’ in front of the cathode for steeper HV pulses. The starting velocity of the positive streamer-like propagation at the rising slope of the HV pulses increases with increasing slope steepness, but without influencing the maximal velocity in front of the cathode. At the falling slope, however, smaller propagation velocities for steeper pulses were measured. The modelling results and the measurements of the emission during the pre-phase suggest that the elevated pre-ionisation and higher electrical energy for steeper HV slopes is responsible for most of the observed effects.

  5. Accelerating Spectrum Sharing Technologies

    SciTech Connect

    Juan D. Deaton; Lynda L. Brighton; Rangam Subramanian; Hussein Moradi; Jose Loera

    2013-09-01

    Spectrum sharing potentially holds the promise of solving the emerging spectrum crisis. However, technology innovators face the conundrum of developing spectrum sharing technologies without the ability to experiment and test with real incumbent systems. Interference with operational incumbents can prevent critical services, and the cost of deploying and operating an incumbent system can be prohibitive. Thus, the lack of incumbent systems and frequency authorization for technology incubation and demonstration has stymied spectrum sharing research. To this end, industry, academia, and regulators all require a test facility for validating hypotheses and demonstrating functionality without affecting operational incumbent systems. This article proposes a four-phase program supported by our spectrum accountability architecture. We propose that our comprehensive experimentation and testing approach for technology incubation and demonstration will accelerate the development of spectrum sharing technologies.

  6. A new principle of coherence in a synchrotron source

    NASA Astrophysics Data System (ADS)

    Singal, Ashok Kumar

    A synchrotron source with a random distribution of velocity vectors for radiating charges will assumedly have no systematic phase relation between radiation fields from individual charges and would thereby give rise to an incoherent emission. It is known that synchrotron radiation mechanism does not allow a MASER type coherent emission. Here we show that a partial coherence due to antenna mechanism can be inherently present in any compact synchrotron source. Synchrotron radiation at an observing frequency selectively arises from relativistic electrons having a narrow range of Lorentz factors and moving in a cone of a narrow opening angle with respect to the line of sight to the observer, and thus having similar velocity vectors. As we show, even opposite charges moving within the cone augment each others radiation fields, contrary to what may be normally expected. The coherence volume grows with wavelength λ as ∝λ^{3}, giving rise to the possibility of coherence occurring at wavelengths larger than a certain value λ_{p} in a source. The coherence resolves many long standing astrophysical problems where theoretical predictions were not borne out by the observational data. For example, the spectrum gets enhanced by a factor ∝λ^{3} in the self-absorbed region. This resolves the observational puzzle of a flat spectrum instead of the theoretical steep slope - known in literature as a ``cosmic conspiracy''. It further explains the brightness temperatures observed in space VLBI up to two orders of magnitude higher than the theoretical incoherent synchrotron limit ˜10^{11.5} K. A simple model for the variability, based on an injection of large number of particles resulting in coherence, explains the observed range of variability time scales (from less than a day to years) and the inferred extremely high brightness temperatures, up to ˜10^{18-19} K, millions of time more than the theoretical limit. Coherence also explains the correlation observed in the optical

  7. Modelling the TSZ power spectrum

    SciTech Connect

    Bhattacharya, Suman; Shaw, Laurie D; Nagai, Daisuke

    2010-01-01

    The structure formation in university is a hierarchical process. As universe evolves, tiny density fluctuations that existed in the early universe grows under gravitational instability to form massive large scale structures. The galaxy clusters are the massive viralized objects that forms by accreting smaller clumps of mass until they collapse under their self-gravity. As such galaxy clusters are the youngest objects in the universe which makes their abundance as a function of mass and redshift, very sensitive to dark energy. Galaxy clusters can be detected by measuring the richness in optical waveband, by measuring the X-ray flux, and in the microwave sky using Sunyaev-Zel'dovich (SZ) effect. The Sunyaev-Zel'dovich (SZ) effect has long been recognized as a powerful tool for detecting clusters and probing the physics of the intra-cluster medium. Ongoing and future experiments like Atacama Cosmology Telescope, the South Pole Telescope and Planck survey are currently surveying the microwave sky to develop large catalogs of galaxy clusters that are uniformly selected by the SZ flux. However one major systematic uncertainties that cluster abundance is prone to is the connection between the cluster mass and the SZ flux. As shown by several simulation studies, the scatter and bias in the SZ flux-mass relation can be a potential source of systematic error to using clusters as a cosmology probe. In this study they take a semi-analytic approach for modeling the intra-cluster medium in order to predict the tSZ power spectrum. The advantage of this approach is, being analytic, one can vary the parameters describing gas physics and cosmology simultaneously. The model can be calibrated against X-ray observations of massive, low-z clusters, and using the SZ power spectrum which is sourced by high-z lower mass galaxy groups. This approach allows us to include the uncertainty in gas physics, as dictated by the current observational uncertainties, while measuring the cosmological

  8. Geomorphic Responses to Check-Dam Removal on a Steep Mountain River in Taiwan

    NASA Astrophysics Data System (ADS)

    Wang, H. W.; Kuo, W. C.

    2014-12-01

    dams in Taiwan are located in steep mountainous area with highly variable hydrologic condition, we anticipate the observations will help enhancing future similar dam removal projects.

  9. Ridge-Runnel and Swash Dynamics Field Experiment on a Steep Meso-Tidal Beach

    NASA Astrophysics Data System (ADS)

    Figlus, J.; Chardon-Maldonado, P.; Puleo, J. A.

    2014-12-01

    Ridge-runnel (RR) systems are morphological features that may form in the intermittently wet and dry zone of the beach immediately after storm events. Their onshore migration provides a natural way of recovery for an eroded beach but the detailed swash interactions and complex feedback mechanisms between wave dynamics, sediment transport and profile evolution are not well understood and challenging to measure in-situ. During a storm, elevated water levels and large waves can significantly erode the beach profile in a matter of hours through offshore-directed sediment transport. The beach recovery process, on the other hand, occurs over a much longer time period during less intense wave conditions. In the beginning of this 3-week field campaign at South Bethany Beach, Delaware, a Nor'easter, eroded significant portions of this steep, meso-tidal beach and formed a pronounced RR system which then evolved during the less energetic conditions after the storm. An extensive cross-shore array of sensors was installed immediately after the storm measuring near-bed velocity profiles (5 Nortek Vectrino Profilers) and horizontal velocities (6 Sontec Electromagnetic Current Meters; 1 side-looking Nortek Vectrino) suspended sediment concentrations (10 Optical Backscatter Sensors OBS-3+), and pressure fluctuations (7 GE Druck pressure transducers) in the swash zone. Dense topography surveys of the RR system were conducted twice a day during low tide conditions with a Leica RTK GPS rover system. In addition, sediment grab samples along the entire RR cross-section were collected daily. An offshore ADCP with surface wave tracking capability (Nortek 2MHz AWAC AST) measured directional wave spectra and current profiles at a water depth of approximately 6m. The RR system showed rapid onshore migration over the two tide cycles immediately after the storm, followed by a period of vertical ridge accretion of up to 3 ft at certain locations. A first look at the collected data and analysis

  10. Laboratory Experiments of Tsunami Inundation in Patchy Coastal Forest on a Steep Beach

    NASA Astrophysics Data System (ADS)

    Irish, J. L.; Weiss, R.; Yang, Y.; Zainali, A.; Marivela Colmenarejo, R.

    2014-12-01

    Tsunamis are a leading natural threat to coastal communities, and events such as the 2011 Japan and 2004 Indian Ocean tsunamis caused widespread, crippling damages to coastal infrastructure. Yet, these events also called attention to the role of coastal forest as sustainable mitigation against tsunami hazard. Here, we present large-scale experiments of tsunami runup and withdrawal on a steeply sloping beach in the presence of patchy forest. The forest is modeled using 1.2-m diameter macro-roughness patches of varying resistance were constructed from staggered arrays of 2.7-cm diameter rigid cylinders. Macro-roughness patches were affixed in a staggered arrangement with mean spacing of 3.2 m between patches (Fig. 1). The basin depth and wave height at the wavemaker were 0.73 m and 0.43 m, respectively, such that a broken roller formed offshore of the still-water line. Point measurements of velocity and flow depth were made at twenty locations using co-located acoustic Doppler velocimeters and sonic wave gauges, respectively, in order to construct a flow field in the vicinity of three macro-roughness patches. Simultaneous, high-resolution video was also collected in order to track the runup bore position in time. Analysis of mean flow conditions reveals that patchy roughness induces non-uniform changes in momentum flux throughout the patch array (Fig. 2). During runup, momentum flux is generally reduced in the lee of the patches. However, flow channelization between cross-shore rows of patches leads to an increase in momentum flux. During withdrawal, the strong gravity-driven flows that develop as a result of the steep 1:10 beach lead to an increase in momentum flux in areas behind the patches, which benefited from reduced momentum flux during runup. The experiment findings indicate that flow interactions with the natural environment are indeed complex and that care must be exercised when considering the use of coastal forest as a tsunami bioshield. Acknowledgements

  11. Venus steep-sided domes: Relationships between geological associations and possible petrogenetic models

    NASA Technical Reports Server (NTRS)

    Pavri, B.; Head, James W., III

    1992-01-01

    Venus domes are characterized by steep sides, a circular shape, and a relatively flat summit area. In addition, they are orders of magnitude larger in volume and have a lower height/diameter ratio than terrestrial silicic lava domes. The morphology of the domes is consistent with formation by lava with a high apparent viscosity. Twenty percent of the domes are located in or near tessera (highly deformed highlands), while most other (62 percent) are located in and near coronae (circular deformational features thought to represent local mantle upwelling). These geological associations provide evidence for mechanisms of petrogenesis and several of these models are found to be plausible: remelting of basaltic or evolved crust, differentiation of basaltic melts, and volatile enhancement and eruption of basaltic foams. Hess and Head have shown that the full range of magma compositions existing on the Earth is plausible under various environmental conditions on Venus. Most of the Venera and Vego lander compostional data are consistent with tholeiitic basalt; however, evidence for evolved magmas was provided by Venera 8 data consistent with a quartz monzonite composition. Pieters et al. have examined the color of the Venus surface from Venera lander images and interpret the surface there to be oxidized. Preliminary modeling of dome growth has provided some interpretations of lava rheology. Viscosity values obtained from these models range from 10(exp 14) - 10(exp 17) pa*s, and the yield strength has been calculated to be between 10(exp 4) and 10(exp 6) Pa, consistent with terrestrial silicic rocks. The apparent high viscosity of the dome lavas suggests that the domes have a silicic composition or must augment their viscosity with increased visicularity or crystal content. Sixty-two percent of the Venus domes are associated with coronae, circular features that have been proposed as sites of mantle upwelling, and 20 percent of the domes are located near tessera, relatively

  12. Quantifying the Temporal and Spatial Response of Channel Steepness to Changes in Rift Basin Architecture

    NASA Astrophysics Data System (ADS)

    Robinson, Scott M.

    Quantifying the temporal and spatial evolution of active continental rifts contributes to our understanding of fault system evolution and seismic hazards. Rift systems also preserve robust paleoenvironmental records and are often characterized by strong climatic gradients that can be used to examine feedbacks between climate and tectonics. In this thesis, I quantify the spatial and temporal history of rift flank uplift by analyzing bedrock river channel profiles along footwall escarpments in the Malawi segment of the East Africa Rift. This work addresses questions that are widely applicable to continental rift settings: (1) Is rift-flank uplift sufficiently described by theoretical elliptical along-fault displacement patterns? (2) Do orographic climate patterns induced by rift topography affect rift-flank uplift or morphology? (3) How do uplift patterns along rift flanks vary over geologic timescales? In Malawi, 100-km-long border faults of alternating polarity bound half-graben sedimentary basins containing up to 4km of basin fill and water depths up to 700m. Orographically driven precipitation produces climatic gradients along footwall escarpments resulting in mean annual rainfall that varies spatially from 800 to 2500 mm. Temporal oscillations in climate have also resulted in lake lowstands 500 m below the modern shoreline. I examine bedrock river profiles crossing the Livingstone and Usisya Border Faults in northern Malawi using the channel steepness index (Ksn) to assess importance of these conditions on rift flank evolution. River profiles reveal a consistent transient pattern that likely preserves a temporal record of slip and erosion along the entire border fault system. These profiles and other topographic observations, along with known modern and paleoenvironmental conditions, can be used to interpret a complete history of rift flank development from the onset of rifting to present. I interpret the morphology of the upland landscape to preserve the onset

  13. BROADBAND RADIO POLARIMETRY AND FARADAY ROTATION OF 563 EXTRAGALACTIC RADIO SOURCES

    SciTech Connect

    Anderson, C. S.; Gaensler, B. M.; Feain, I. J.; Franzen, T. M. O.

    2015-12-10

    We present a broadband spectropolarimetric survey of 563 discrete, mostly unresolved radio sources between 1.3 and 2.0 GHz using data taken with the Australia Telescope Compact Array. We have used rotation-measure synthesis to identify Faraday-complex polarized sources, those objects whose frequency-dependent polarization behavior indicates the presence of material possessing complicated magnetoionic structure along the line of sight (LOS). For sources classified as Faraday-complex, we have analyzed a number of their radio and multiwavelength properties to determine whether they differ from Faraday-simple polarized sources (sources for which LOS magnetoionic structures are comparatively simple) in these properties. We use this information to constrain the physical nature of the magnetoionic structures responsible for generating the observed complexity. We detect Faraday complexity in 12% of polarized sources at ∼1′ resolution, but we demonstrate that underlying signal-to-noise limitations mean the true percentage is likely to be significantly higher in the polarized radio source population. We find that the properties of Faraday-complex objects are diverse, but that complexity is most often associated with depolarization of extended radio sources possessing a relatively steep total intensity spectrum. We find an association between Faraday complexity and LOS structure in the Galactic interstellar medium (ISM) and claim that a significant proportion of the Faraday complexity we observe may be generated at interfaces of the ISM associated with ionization fronts near neutral hydrogen structures. Galaxy cluster environments and internally generated Faraday complexity provide possible alternative explanations in some cases.

  14. Broadband Radio Polarimetry and Faraday Rotation of 563 Extragalactic Radio Sources

    NASA Astrophysics Data System (ADS)

    Anderson, C. S.; Gaensler, B. M.; Feain, I. J.; Franzen, T. M. O.

    2015-12-01

    We present a broadband spectropolarimetric survey of 563 discrete, mostly unresolved radio sources between 1.3 and 2.0 GHz using data taken with the Australia Telescope Compact Array. We have used rotation-measure synthesis to identify Faraday-complex polarized sources, those objects whose frequency-dependent polarization behavior indicates the presence of material possessing complicated magnetoionic structure along the line of sight (LOS). For sources classified as Faraday-complex, we have analyzed a number of their radio and multiwavelength properties to determine whether they differ from Faraday-simple polarized sources (sources for which LOS magnetoionic structures are comparatively simple) in these properties. We use this information to constrain the physical nature of the magnetoionic structures responsible for generating the observed complexity. We detect Faraday complexity in 12% of polarized sources at ∼1‧ resolution, but we demonstrate that underlying signal-to-noise limitations mean the true percentage is likely to be significantly higher in the polarized radio source population. We find that the properties of Faraday-complex objects are diverse, but that complexity is most often associated with depolarization of extended radio sources possessing a relatively steep total intensity spectrum. We find an association between Faraday complexity and LOS structure in the Galactic interstellar medium (ISM) and claim that a significant proportion of the Faraday complexity we observe may be generated at interfaces of the ISM associated with ionization fronts near neutral hydrogen structures. Galaxy cluster environments and internally generated Faraday complexity provide possible alternative explanations in some cases.

  15. Psychopharmacology of autism spectrum disorders.

    PubMed

    Kaplan, Gabriel; McCracken, James T

    2012-02-01

    At present, no evidence-based effective pharmacologic options are available for treating the core deficits of autism spectrum disorders (ASDs), which are best addressed by behavioral and educational interventions. However, such evidence exists for several of the frequently associated/comorbid symptoms such as aggression and severe irritability, hyperactivity, and repetitive behaviors, which can become a major source of additional distress and interference in functioning. This article offers information on the psychopharmacology of ASD that is current, relevant, and organized in a user-friendly manner, to form a concise but informative reference guide for primary pediatric clinicians.

  16. Fetal Alcohol Spectrum Disorder

    ERIC Educational Resources Information Center

    Caley, Linda M.; Kramer, Charlotte; Robinson, Luther K.

    2005-01-01

    Fetal alcohol spectrum disorder (FASD) is a serious and widespread problem in this country. Positioned within the community with links to children, families, and healthcare systems, school nurses are a critical element in the prevention and treatment of those affected by fetal alcohol spectrum disorder. Although most school nurses are familiar…

  17. The CMBR spectrum

    SciTech Connect

    Stebbins, A.

    1997-05-01

    Here we give an introduction to the observed spectrum of the Cosmic Microwave Background Radiation (CMBR) and discuss what can be learned about it. Particular attention will be given to how Compton scattering can distort the spectrum of the CMBR. An incomplete bibliography of relevant papers is also provided.

  18. CO map and steep Kennicutt-Schmidt relation in the extended UV disk of M 63

    NASA Astrophysics Data System (ADS)

    Dessauges-Zavadsky, M.; Verdugo, C.; Combes, F.; Pfenniger, D.

    2014-06-01

    to r25, the K-S relation is almost linear (with a slope of nearly 1 in log space), in the external UV region the SFR regime is highly nonlinear and characterized by a steep K-S relation (with a slope much higher than 1 in log space) and very low star formation efficiency. Based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

  19. Dense, gravity-driven granular-liquid flows down steep channels

    NASA Astrophysics Data System (ADS)

    Armanini, A.; Larcher, M.; Nucci, E.

    2011-12-01

    Debris flows are complex natural phenomena, characterized by a mixture of poorly sorted sediments and water driven by gravity. Depending on the size distribution, on the volume concentration of sediments and on the geometry and topography of the channel, flow conditions may be very different, ranging from very fast flows, dominated by granular collisions and by the turbulence on the liquid phase, to very slow and dense flows, dominated by the frictional contacts among the grains. To investigate the basic physics of debris flows, it is very useful to analyze the flow of a mixture of identical spherical particles saturated by water and driven by gravity down a steep channel in steady flow condition (Armanini et al. 2005). The flow presents three regions: an external one, near to the free surface, dominated by nearly instantaneous contacts among the particles (collisional regime), an internal region dominated by prolonged contacts among the particles (frictional regime) and a static bed in which the particles are immobile. The detailed vertical structure of this kind of flows was obtained by means of experiments carried out by Armanini et al. (2005) and Larcher et al. (2007). Armanini et al. (2009) analysed the stratification of rheological mechanisms inside the flow, focusing on the coexistence of frictional and collisional regimes, on the stress transmission inside the flow and on particles kinematics. In particular, it was observed that debris flows may show locally a typical intermittence of the flow regime, switching alternatively from frictional to collisional. While the rheology of the collisional layers is well described by the dense gas analogy (kinetic theory), a persuasive theoretical description of the frictional regime does not yet exist. A Coulombian scheme is often assumed, but this hypothesis is rather limitative because it requires a constant concentration or a distribution of particles concentration known a priori. An interesting scheme of this kind

  20. Hillslope-channel coupling in a steep Hawaiian catchment accelerates erosion rates over 100-fold

    NASA Astrophysics Data System (ADS)

    Stock, J. D.; Hanshaw, M. N.; Rosener, M.; Schmidt, K. M.; Brooks, B. A.; Tribble, G.; Jacobi, J.

    2009-12-01

    In tropical watersheds, hillslope changes are producing increasing amounts of fine sediment that can be quickly carried to reefs by channels. Suspended sediment concentrations off the reefs of Molokai, Hawaii, chronically exceed a toxic level of 10 mg/L, threatening reef ecosystems. We hypothesize that historic conversion of watersheds from soil creep to overland flow erosion increased both magnitude and frequency of sediment flooding adjacent reefs. We combined surficial and ecological mapping, hillslope and stream gages, and novel sensors to locate, quantify and model the generation of fine sediments polluting the Molokai reef. Ecological and geomorphic mapping from LiDAR and multi-spectral imagery located a subset of overland flow areas with vegetation cover below a threshold value preventing erosion. Here, feral goat grazing exposed cohesive volcanic soils whose low matrix hydraulic conductivities (1-20 mm/hour) promote Horton overland flow erosion. We instrumented steep, barren hillslopes with soil moisture sensors, overland flow meters, Parshall flumes, ISCO sediment samplers, and a rain gage and conducted repeat Tripod LiDAR and infiltration tests. To characterize soil resistance here and elsewhere to overland flow erosion, we deployed a Cohesive Strength Meter (CSM) to simulate the stresses of flowing water. At the 13.5 km 2 watershed mouth we used a USGS stream gage and ISCO sediment sampler to estimate total load. Over 2 years, storms triggered overland flow during rainfall intensities above 10-15 mm/hr. Overland flow meters indicate such flows can be up to 3 cm deep, with a tendency to deepen downslope. CSM tests indicate that these depths are insufficient to erode soils where vegetation is dense, but far above threshold values of 2-3 mm depth for bare soil erosion. Sediment ratings curves for both hillslope and downstream catchment gages show strong clock-wise hysteresis during the first intense storms in the Fall, becoming linear later in the rainy

  1. Quantifying the temporal and spatial response of channel steepness to changes in rift basin architecture

    NASA Astrophysics Data System (ADS)

    Robinson, S. M.; Whipple, K. X.; Arrowsmith, R.; Heimsath, A. M.; Foster, M.; Cohen, A. S.

    2013-12-01

    Quantifying the temporal evolution of active continental rifts contributes to our understanding of fault system evolution and seismic hazards. Rift basins also preserve robust paleoenvironmental records that may help untangle feedbacks between climate and tectonics. Here we quantify the spatial and temporal history of rift flank uplift by exploiting landscape memory along footwall escarpments in the Malawi segment of the East Africa Rift. Our work helps answer a suite of questions that are widely applicable to continental rift settings; (1) Is rift-flank uplift well described by theoretical elliptical displacement patterns? (2) Do orographic climate patterns induced by rift topography affect rift-flank uplift? (3) Is footwall exhumation influenced by the evolution of depocenters and rift lakes? In Malawi, 100 km long border faults of alternating polarity bound half-graben sedimentary basins containing up to 4km of basin fill and water depths up to 700m. Orographically driven precipitation produces climatic gradients along footwall escarpments resulting in mean annual precipitation that varies spatially from 800 to 2500mm. Temporal oscillations in climate have also resulted in lake lowstands 500m below the modern Lake Malawi. We examine bedrock river profiles crossing the Livingstone and Usisya Border Faults in northern Malawi using the channel steepness index (Ksn). River profiles reveal consistent patterns of Ksn throughout the study area. Typical profiles contain a lower reach with Ksn values between 150-300 and an upper reach with values between 50-150. Some channels display an uppermost reach with values less than 100 that are interpreted to represent the pre to early-rift relief of the region. This progressive downstream steepening is consistent with acceleration of slip along the main border faults or reduction in climatically modulated erosional efficiency. Spatial patterns of Ksn and knickpoint elevations are not consistent with theoretical along fault

  2. Production of 1,3-propanediol by Clostridium beijerinckii DSM 791 from crude glycerol and corn steep liquor: Process optimization and metabolic engineering.

    PubMed

    Wischral, Daiana; Zhang, Jianzhi; Cheng, Chi; Lin, Meng; De Souza, Lucas Monteiro Galotti; Pessoa, Fernando L Pellegrini; Pereira, Nei; Yang, Shang-Tian

    2016-07-01

    1,3-Propanediol (1,3-PDO) production from crude glycerol, a byproduct from biodiesel manufacturing, by Clostridium beijerinckii DSM 791 was studied with corn steep liquor as an inexpensive nitrogen source replacing yeast extract in the fermentation medium. A stable, long-term 1,3-PDO production from glycerol was demonstrated with cells immobilized in a fibrous bed bioreactor operated in a repeated batch mode, which partially circumvented the 1,3-PDO inhibition problem. The strain was then engineered to overexpress Escherichia coli gldA encoding glycerol dehydrogenase (GDH) and dhaKLM encoding dihydroxyacetone kinase (DHAK), which increased 1,3-PDO productivity by 26.8-37.5% compared to the wild type, because of greatly increased specific growth rate (0.25-0.40h(-1) vs. 0.13-0.20h(-1) for the wild type). The engineered strain gave a high 1,3-PDO titer (26.1g/L), yield (0.55g/g) and productivity (0.99g/L·h) in fed-batch fermentation. Overexpressing GDH and DHAK was thus effective in increasing 1,3-PDO production from glycerol.

  3. Impact of change in erosion rate and landscape steepness on hillslope and fluvial sediments grain size in the Feather River basin (Sierra Nevada, California)

    NASA Astrophysics Data System (ADS)

    Attal, M.; Mudd, S. M.; Hurst, M. D.; Weinman, B.; Yoo, K.; Naylor, M.

    2015-03-01

    The characteristics of the sediment transported by rivers (e.g. sediment flux, grain size distribution - GSD) dictate whether rivers aggrade or erode their substrate. They also condition the architecture and properties of sedimentary successions in basins. In this study, we investigate the relationship between landscape steepness and the grain size of hillslope and fluvial sediments. The study area is located within the Feather River basin in northern California, and studied basins are underlain exclusively by tonalite lithology. Erosion rates in the study area vary over an order of magnitude, from >250 mm ka-1 in the Feather River canyon to <15 mm ka-1 on an adjacent low-relief plateau. We find that the coarseness of hillslope sediment increases with increasing hillslope steepness and erosion rates. We hypothesise that, in our soil samples, the measured 10-fold increase in D50 and doubling of the amount of fragments larger than 1 mm when slope increases from 0.38 to 0.83 m m-1 is due to a decrease in the residence time of rock fragments, causing particles to be exposed for shorter periods of time to processes that can reduce grain size. For slopes in excess of 0.7 m m-1, landslides and scree cones supply much coarser sediment to rivers, with D50 and D84 more than one order of magnitude larger than in soils. In the tributary basins of the Feather River, a prominent break in slope developed in response to the rapid incision of the Feather River. Downstream of the break in slope, fluvial sediment grain size increases, due to an increase in flow competence (mostly driven by channel steepening) as well as a change in sediment source and in sediment dynamics: on the plateau upstream of the break in slope, rivers transport easily mobilised fine-grained sediment derived exclusively from soils. Downstream of the break in slope, mass wasting processes supply a wide range of grain sizes that rivers entrain selectively, depending on the competence of their flow. Our results

  4. Why lower diatremes in kimberlitic and non-kimberlitic systems are non-stratified, homogenized, and contain steep internal contacts: episodic bursts and debris jets

    NASA Astrophysics Data System (ADS)

    Ross, P.; White, J. D.; Kurszlaukis, S.; Lorenz, V.; Zimanowski, B.; Buettner, R.; McClintock, M.

    2009-05-01

    In both kimberlitic and non-kimberlitic systems, the volcaniclastic fill of the lower diatreme zone is often described as "homogenized" or "well mixed". Although the components come from different sources, the deposits display "a crude degree of textural and lithological consistency" (Clement and Reid, 1989, "Kimberlites and related rocks", p. 632-646). Bedding is typically absent from the lower diatreme but in some pipes, columnar bodies of volcaniclastic material occur. These bodies have steep contacts with, and a different grain size, componentry, etc. than, the enclosing host. Sometimes the difference can be subtle and the contacts gradational, making recognition difficult. Good examples are documented from Arizona and Antarctica in basaltic systems and such columnar bodies are also known in kimberlites, where they are sometimes called "feeder conduits". Both the homogenized aspect of many diatremes, and the generation of steep internal contacts, have been attributed to whole-pipe fluidization by some recent workers. This process is unlikely to occur in large pipes because it would take a huge amount of gas being emitted at a sufficient rate to fluidize the whole pipe. Other recent models call for Plinian-scale eruptions. However it is clear that small episodic bursts, not sustained Plinian plumes, must explain the genesis of the hundreds of relatively thin beds in maar tephra rims (maar- diatreme volcanoes do not generate large ignimbrites or thick widespread pyroclastic fall layers). Here we examine what these episodic bursts may do to the underground part of the maar-diatreme volcano. An explosion at deep levels in the pipe will generate enough gas to mobilize newly fragmented magma and existing debris upward into a "debris jet", typically much narrower than the width of the diatreme. Debris jets propagate within the existing diatreme fill and may or may not reach the surface. Experimental studies can be used to illustrate the processes at work. With time

  5. Universal Spectrum of Two-Dimensional Turbulence on a Rotating Sphere and Some Basic Features of Atmospheric Circulation on Giant Planets

    NASA Astrophysics Data System (ADS)

    Sukoriansky, Semion; Galperin, Boris; Dikovskaya, Nadejda

    2002-08-01

    The Kolmogorov-Batchelor-Kraichnan (KBK) theory of two-dimensional turbulence is generalized for turbulence on the surface of a rotating sphere. The energy spectrum develops considerable anisotropy; a steep -5 slope emerges in the zonal direction, while in all others the classical KBK scaling prevails. This flow regime in robust steady state is reproduced in simulations with linear drag. The conditions favorable for this regime may be common for giant planets' atmospheric circulations; the same steep spectra are found in their observed zonal velocity profiles and utilized to explain their basic characteristics.

  6. Development of a digital guidance and control law for steep approach automatic landings using modern control techniques

    NASA Technical Reports Server (NTRS)

    Halyo, N.

    1979-01-01

    The development of a digital automatic control law for a small jet transport to perform a steep final approach in automatic landings is reported along with the development of a steady-state Kalman filter used to provide smooth estimates to the control law. The control law performs the functions of localizer and glides capture, localizer and glideslope track, decrab, and place. The control law uses the microwave landing system position data, and aircraft body-mounted accelerators, attitude and attitude rate information. The results obtained from a digital simulation of the aircraft dynamics, wind conditions, and sensor noises using the control law and filter developed are described.

  7. Sensitivity analysis of helicopter IMC decelerating steep approach and landing performance to navigation system parameters. [Instrument Meteorological Conditions

    NASA Technical Reports Server (NTRS)

    Karmali, M. S.; Phatak, A. V.; Bull, J. S.; Peach, L. L.; Demko, P. S.

    1984-01-01

    The present investigation is concerned with a sensitivity analysis of the Decelerated Steep Approach and Landing (DSAL) maneuver to on-board and ground-based navigation system parameters. The Instrument Meteorological Conditions (IMC) DSAL maneuver involves decelerating to zero range rate while tracking the localizer and glideslope. The considered study investigated the performance of the navigation systems using Constant Deceleration Profile (CDP) guidance and a six degrees glideslope trajectory. A closed-loop computer simulation of the UH1H helicopter DSAL system was developed for the sensitivity analysis. Conclusions on system performance parameter sensitivity are discussed.

  8. Development of an optimal automatic control law and filter algorithm for steep glideslope capture and glideslope tracking

    NASA Technical Reports Server (NTRS)

    Halyo, N.

    1976-01-01

    A digital automatic control law to capture a steep glideslope and track the glideslope to a specified altitude is developed for the longitudinal/vertical dynamics of a CTOL aircraft using modern estimation and control techniques. The control law uses a constant gain Kalman filter to process guidance information from the microwave landing system, and acceleration from body mounted accelerometer data. The filter outputs navigation data and wind velocity estimates which are used in controlling the aircraft. Results from a digital simulation of the aircraft dynamics and the control law are presented for various wind conditions.

  9. Diffusion Profiles of Health Beneficial Components from Goji Berry (Lyceum barbarum) Marinated in Alcohol and Their Antioxidant Capacities as Affected by Alcohol Concentration and Steeping Time.

    PubMed

    Song, Yang; Xu, Baojun

    2013-01-25

    The fruit (goji berry) of Lycium barbarum, a traditional Chinese medicine, has been widely used in health diets due to its potential role in the prevention of chronic diseases. One of the most popular applications of goji berry is to make goji wine in China by steeping goji berry in grain liquor. However, how the steeping process affects antioxidant capacities and phytochemicals of goji berry is not yet fully understood. Therefore, to provide scientific data for the utilization of goji berry in the nutraceutical industry, the diffusion rate of betaine, β-carotene, phenolic compounds in goji berry and their antioxidant capacities affected by alcohol concentration and steeping time were determined by UV-Visible spectrophotometer. The results showed that low alcohol concentration (15% or 25%) would promote the diffusion of betaine and increase antioxidant activity, while high concentration (55% or 65%) would generally increase the diffusion of flavonoids and reduce antioxidant activity. The steeping time had no significant effect on the diffusion of phenolic compounds and antioxidant activities. However, all goji berry wine steeped for 14 days with different alcohol concentrations exhibited the highest betaine concentration. Current findings provide useful information for the nutraceutical industries to choose proper steeping time and alcohol concentration to yield desired health promotion components from goji.

  10. Diffusion Profiles of Health Beneficial Components from Goji Berry (Lyceum barbarum) Marinated in Alcohol and Their Antioxidant Capacities as Affected by Alcohol Concentration and Steeping Time

    PubMed Central

    Song, Yang; Xu, Baojun

    2013-01-01

    The fruit (goji berry) of Lycium barbarum, a traditional Chinese medicine, has been widely used in health diets due to its potential role in the prevention of chronic diseases. One of the most popular applications of goji berry is to make goji wine in China by steeping goji berry in grain liquor. However, how the steeping process affects antioxidant capacities and phytochemicals of goji berry is not yet fully understood. Therefore, to provide scientific data for the utilization of goji berry in the nutraceutical industry, the diffusion rate of betaine, β-carotene, phenolic compounds in goji berry and their antioxidant capacities affected by alcohol concentration and steeping time were determined by UV-Visible spectrophotometer. The results showed that low alcohol concentration (15% or 25%) would promote the diffusion of betaine and increase antioxidant activity, while high concentration (55% or 65%) would generally increase the diffusion of flavonoids and reduce antioxidant activity. The steeping time had no significant effect on the diffusion of phenolic compounds and antioxidant activities. However, all goji berry wine steeped for 14 days with different alcohol concentrations exhibited the highest betaine concentration. Current findings provide useful information for the nutraceutical industries to choose proper steeping time and alcohol concentration to yield desired health promotion components from goji. PMID:28239094

  11. IRIS Spectrum Line Plot

    NASA Video Gallery

    This video shows a line plot of the spectrum. The spectra here are shown for various locations on the Sun. The changes in the movie are caused by differing physical conditions in the locations. Cre...

  12. Quantum Spread Spectrum Communication

    SciTech Connect

    Humble, Travis S

    2010-01-01

    We demonstrate that spectral teleportation can coherently dilate the spectral probability amplitude of a single photon. In preserving the encoded quantum information, this variant of teleportation subsequently enables a form of quantum spread spectrum communication.

  13. Autism Spectrum Disorder (ASD)

    MedlinePlus

    ... essential data on ASD, search for factors that put children at risk for ASD and possible causes, ... United States to help identify factors that may put children at risk for autism spectrum disorder (ASD) ...

  14. Autism Spectrum Disorder (ASD)

    MedlinePlus

    ... NICHD Research Information Clinical Trials Resources and Publications Autism Spectrum Disorder (ASD): Condition Information Skip sharing on ... Restricted interests and repetitive behaviors Different people with autism can have different symptoms. For this reason, autism ...

  15. Chandra Observations of Dying Radio Sources in Galaxy Clusters

    NASA Technical Reports Server (NTRS)

    Murgia, M.; Markevitch, M.; Govoni, F.; Parma, P.; Fanti, R.; de Ruiter, H. R.; Mack, K.-H.

    2012-01-01

    Context. The dying radio sources represent a very interesting and largely unexplored stage of the active galactic nucleus (AGN) evolution. They are considered to be very rare, and almost all of the few known ones were found in galaxy clusters. However, considering the small number detected so far, it has not been possible to draw any firm conclusions about their X-ray environment. Aims. We present X-ray observations performed with the Chandra satellite of the three galaxy clusters Abell 2276, ZwCl 1829.3+6912, and RX J1852.1+5711, which harbor at their center a dying radio source with an ultra-steep spectrum that we recently discovered. Methods. We analyzed the physical properties of the X-ray emitting gas surrounding these elusive radio sources. We determined the global X-ray properties of the clusters, derived the azimuthally averaged profiles of metal abundance, gas temperature, density, and pressure. Furthermore, we estimated the total mass profiles. Results. The large-scale X-ray emission is regular and spherical, suggesting a relaxed state for these systems. Indeed, we found that the three clusters are also characterized by significant enhancements in the metal abundance and declining temperature profiles toward the central region. For all these reasons, we classified RX J1852.1+5711, Abell 2276, and ZwCl 1829.3+6912 as cool-core galaxy clusters. Conclusions. We calculated the non-thermal pressure of the radio lobes assuming that the radio sources are in the minimum energy condition. For all dying sources we found that this is on average about one to two orders of magnitude lower than that of the external gas, as found for many other radio sources at the center of galaxy groups and clusters. We found marginal evidence for the presence of X-ray surface brightness depressions coincident with the fossil radio lobes of the dying sources in A2276 and ZwCl 1829.3+691. We estimated the outburst age and energy output for these two dying sources. The energy power from

  16. Chandra observations of dying radio sources in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Murgia, M.; Markevitch, M.; Govoni, F.; Parma, P.; Fanti, R.; de Ruiter, H. R.; Mack, K.-H.

    2012-12-01

    Context. The dying radio sources represent a very interesting and largely unexplored stage of the active galactic nucleus (AGN) evolution. They are considered to be very rare, and almost all of the few known ones were found in galaxy clusters. However, considering the small number detected so far, it has not been possible to draw any firm conclusions about their X-ray environment. Aims: We present X-ray observations performed with the Chandra satellite of the three galaxy clusters Abell 2276, ZwCl 1829.3+6912, and RX J1852.1+5711, which harbor at their center a dying radio source with an ultra-steep spectrum that we recently discovered. Methods: We analyzed the physical properties of the X-ray emitting gas surrounding these elusive radio sources. We determined the global X-ray properties of the clusters, derived the azimuthally averaged profiles of metal abundance, gas temperature, density, and pressure. Furthermore, we estimated the total mass profiles. Results: The large-scale X-ray emission is regular and spherical, suggesting a relaxed state for these systems. Indeed, we found that the three clusters are also characterized by significant enhancements in the metal abundance and declining temperature profiles toward the central region. For all these reasons, we classified RX J1852.1+5711, Abell 2276, and ZwCl 1829.3+6912 as cool-core galaxy clusters. Conclusions: We calculated the non-thermal pressure of the radio lobes assuming that the radio sources are in the minimum energy condition. For all dying sources we found that this is on average about one to two orders of magnitude lower than that of the external gas, as found for many other radio sources at the center of galaxy groups and clusters. We found marginal evidence for the presence of X-ray surface brightness depressions coincident with the fossil radio lobes of the dying sources in A2276 and ZwCl 1829.3+691. We estimated the outburst age and energy output for these two dying sources. The energy power from

  17. Steep spatial gradients of volcanic and marine sulfur in Hawaiian rainfall and ecosystems

    USGS Publications Warehouse

    Bern, Carleton R.; Chadwick, Oliver A.; Kendall, Carol; Pribil, Michael J.

    2015-01-01

    Sulfur, a nutrient required by terrestrial ecosystems, is likely to be regulated by atmospheric processes in well-drained, upland settings because of its low concentration in most bedrock and generally poor retention by inorganic reactions within soils. Environmental controls on sulfur sources in unpolluted ecosystems have seldom been investigated in detail, even though the possibility of sulfur limiting primary production is much greater where atmospheric deposition of anthropogenic sulfur is low. Here we measure sulfur isotopic compositions of soils, vegetation and bulk atmospheric deposition from the Hawaiian Islands for the purpose of tracing sources of ecosystem sulfur. Hawaiian lava has a mantle-derived sulfur isotopic composition (δ34S VCDT) of − 0.8‰. Bulk deposition on the island of Maui had a δ34S VCDT that varied temporally, spanned a range from + 8.2 to + 19.7‰, and reflected isotopic mixing from three sources: sea-salt (+ 21.1‰), marine biogenic emissions (+ 15.6‰), and volcanic emissions from active vents on Kilauea Volcano (+ 0.8‰). A straightforward, weathering-driven transition in ecosystem sulfur sources could be interpreted in the shift from relatively low (0.0 to + 2.7‰) to relatively high (+ 17.8 to + 19.3‰) soil δ34S values along a 0.3 to 4100 ka soil age-gradient, and similar patterns in associated vegetation. However, sub-kilometer scale spatial variation in soil sulfur isotopic composition was found along soil transects assumed by age and mass balance to be dominated by atmospheric sulfur inputs. Soil sulfur isotopic compositions ranged from + 8.1 to + 20.3‰ and generally decreased with increasing elevation (0–2000 m), distance from the coast (0–12 km), and annual rainfall (180–5000 mm). Such trends reflect the spatial variation in marine versus volcanic inputs from atmospheric deposition. Broadly, these results illustrate how the sources and magnitude of atmospheric deposition can exert controls

  18. Steep spatial gradients of volcanic and marine sulfur in Hawaiian rainfall and ecosystems.

    PubMed

    Bern, Carleton R; Chadwick, Oliver A; Kendall, Carol; Pribil, Michael J

    2015-05-01

    Sulfur, a nutrient required by terrestrial ecosystems, is likely to be regulated by atmospheric processes in well-drained, upland settings because of its low concentration in most bedrock and generally poor retention by inorganic reactions within soils. Environmental controls on sulfur sources in unpolluted ecosystems have seldom been investigated in detail, even though the possibility of sulfur limiting primary production is much greater where atmospheric deposition of anthropogenic sulfur is low. Here we measure sulfur isotopic compositions of soils, vegetation and bulk atmospheric deposition from the Hawaiian Islands for the purpose of tracing sources of ecosystem sulfur. Hawaiian lava has a mantle-derived sulfur isotopic composition (δ(34)S VCDT) of -0.8‰. Bulk deposition on the island of Maui had a δ(34)S VCDT that varied temporally, spanned a range from +8.2 to +19.7‰, and reflected isotopic mixing from three sources: sea-salt (+21.1‰), marine biogenic emissions (+15.6‰), and volcanic emissions from active vents on Kilauea Volcano (+0.8‰). A straightforward, weathering-driven transition in ecosystem sulfur sources could be interpreted in the shift from relatively low (0.0 to +2.7‰) to relatively high (+17.8 to +19.3‰) soil δ(34)S values along a 0.3 to 4100 ka soil age-gradient, and similar patterns in associated vegetation. However, sub-kilometer scale spatial variation in soil sulfur isotopic composition was found along soil transects assumed by age and mass balance to be dominated by atmospheric sulfur inputs. Soil sulfur isotopic compositions ranged from +8.1 to +20.3‰ and generally decreased with increasing elevation (0-2000 m), distance from the coast (0-12 km), and annual rainfall (180-5000 mm). Such trends reflect the spatial variation in marine versus volcanic inputs from atmospheric deposition. Broadly, these results illustrate how the sources and magnitude of atmospheric deposition can exert controls over ecosystem sulfur

  19. A Bio-Realistic Analog CMOS Cochlea Filter With High Tunability and Ultra-Steep Roll-Off.

    PubMed

    Wang, Shiwei; Koickal, Thomas Jacob; Hamilton, Alister; Cheung, Rebecca; Smith, Leslie S

    2015-06-01

    This paper presents the design and experimental results of a cochlea filter in analog very large scale integration (VLSI) which highly resembles physiologically measured response of the mammalian cochlea. The filter consists of three specialized sub-filter stages which respectively provide passive response in low frequencies, actively tunable response in mid-band frequencies and ultra-steep roll-off at transition frequencies from pass-band to stop-band. The sub-filters are implemented in balanced ladder topology using floating active inductors. Measured results from the fabricated chip show that wide range of mid-band tuning including gain tuning of over 20 dB, Q factor tuning from 2 to 19 as well as the bio-realistic center frequency shift are achieved by adjusting only one circuit parameter. Besides, the filter has an ultra-steep roll-off reaching over 300 dB/dec. By changing biasing currents, the filter can be configured to operate with center frequencies from 31 Hz to 8 kHz. The filter is 9th order, consumes 59.5 ∼ 90.0 μW power and occupies 0.9 mm2 chip area. A parallel bank of the proposed filter can be used as the front-end in hearing prosthesis devices, speech processors as well as other bio-inspired auditory systems owing to its bio-realistic behavior, low power consumption and small size.

  20. Steepness of the radiation dose-response curve for dose-per-fraction escalation keeping the number of fractions fixed.

    PubMed

    Bentzen, Søren M

    2005-01-01

    Clinically, there is growing interest in strategies for intensifying radiation therapy by escalating the dose per fraction. This paper considers the steepness of the dose-response curve in this case. The steepness of a radiation dose-response curve is most conveniently quantified by the normalized dose-response gradient, gamma. Under the assumption of a linear-quadratic dose-effect model, a simple analytical relationship is derived between the gamma-value for a dose-response curve generated by varying the total dose while keeping the number of fractions constant, i.e. escalating the dose per fraction, and the gamma-value for a dose-response curve generated by varying the total dose while keeping the dose per fraction constant. This formulation is compared with clinical dose-response data from the literature and shown to be in good agreement with the observations. Some implications of this formulation for non-uniform dose distributions delivered using 3D conformal radiotherapy or intensity modulated radiotherapy (IMRT) are briefly discussed.

  1. The Spectrum of Wind Power Fluctuations

    NASA Astrophysics Data System (ADS)

    Bandi, Mahesh

    2016-11-01

    Wind is a variable energy source whose fluctuations threaten electrical grid stability and complicate dynamical load balancing. The power generated by a wind turbine fluctuates due to the variable wind speed that blows past the turbine. Indeed, the spectrum of wind power fluctuations is widely believed to reflect the Kolmogorov spectrum; both vary with frequency f as f - 5 / 3. This variability decreases when aggregate power fluctuations from geographically distributed wind farms are averaged at the grid via a mechanism known as geographic smoothing. Neither the f - 5 / 3 wind power fluctuation spectrum nor the mechanism of geographic smoothing are understood. In this work, we explain the wind power fluctuation spectrum from the turbine through grid scales. The f - 5 / 3 wind power fluctuation spectrum results from the largest length scales of atmospheric turbulence of order 200 km influencing the small scales where individual turbines operate. This long-range influence spatially couples geographically distributed wind farms and synchronizes farm outputs over a range of frequencies and decreases with increasing inter-farm distance. Consequently, aggregate grid-scale power fluctuations remain correlated, and are smoothed until they reach a limiting f - 7 / 3 spectrum. This work was funded by the Collective Interactions Unit, OIST Graduate University, Japan.

  2. Micro acoustic spectrum analyzer

    DOEpatents

    Schubert, W. Kent; Butler, Michael A.; Adkins, Douglas R.; Anderson, Larry F.

    2004-11-23

    A micro acoustic spectrum analyzer for determining the frequency components of a fluctuating sound signal comprises a microphone to pick up the fluctuating sound signal and produce an alternating current electrical signal; at least one microfabricated resonator, each resonator having a different resonant frequency, that vibrate in response to the alternating current electrical signal; and at least one detector to detect the vibration of the microfabricated resonators. The micro acoustic spectrum analyzer can further comprise a mixer to mix a reference signal with the alternating current electrical signal from the microphone to shift the frequency spectrum to a frequency range that is a better matched to the resonant frequencies of the microfabricated resonators. The micro acoustic spectrum analyzer can be designed specifically for portability, size, cost, accuracy, speed, power requirements, and use in a harsh environment. The micro acoustic spectrum analyzer is particularly suited for applications where size, accessibility, and power requirements are limited, such as the monitoring of industrial equipment and processes, detection of security intrusions, or evaluation of military threats.

  3. Broad spectrum solar cell

    DOEpatents

    Walukiewicz, Wladyslaw; Yu, Kin Man; Wu, Junqiao; Schaff, William J.

    2007-05-15

    An alloy having a large band gap range is used in a multijunction solar cell to enhance utilization of the solar energy spectrum. In one embodiment, the alloy is In.sub.1-xGa.sub.xN having an energy bandgap range of approximately 0.7 eV to 3.4 eV, providing a good match to the solar energy spectrum. Multiple junctions having different bandgaps are stacked to form a solar cell. Each junction may have different bandgaps (realized by varying the alloy composition), and therefore be responsive to different parts of the spectrum. The junctions are stacked in such a manner that some bands of light pass through upper junctions to lower junctions that are responsive to such bands.

  4. An unusual meteor spectrum

    NASA Technical Reports Server (NTRS)

    Cook, A. F.; Hemenway, C. L.; Millman, P. M.; Swider, A.

    1973-01-01

    An extraordinary spectrum of a meteor at a velocity of about 18.5 + or - 1.0 km/s was observed with an image orthicon camera. The radiant of the meteor was at an altitude of about 49 deg. It was first seen showing a yellow red continuous spectrum alone at a height of 137 + or - 8 km which is ascribed to the first positive group of nitrogen bands. After the meteor had descended to 116 + or - 6 km above sea level it brightened rapidly from its previous threshold brightness into a uniform continuum, the D-line of neutral sodium appeared, and at height 105 + or - 5 km all the other lines of the spectrum also appeared. The continuum remained dominant to the end. Water of hydration and entrained carbon flakes of characteristic dimension about 0.2 micron or less are proposed as constituents of the meteoroid to explain these phenomena.

  5. Feeding barley grain steeped in lactic acid modulates rumen fermentation patterns and increases milk fat content in dairy cows.

    PubMed

    Iqbal, S; Zebeli, Q; Mazzolari, A; Bertoni, G; Dunn, S M; Yang, W Z; Ametaj, B N

    2009-12-01

    The objectives of the present in vivo and in situ trials were to evaluate whether feeding barley grain steeped in lactic acid (LA) would affect rumen fermentation patterns, in situ dry matter (DM) degradation kinetics, and milk production and composition in lactating dairy cows. The in vivo trial involved 8 rumen-fistulated Holstein cows fed once daily a total mixed ration containing rolled barley grain (27% in DM) steeped for 48 h in an equal quantity of tap water (CTR) or in 0.5% LA (TRT) in a 2 x 2 crossover design. The in situ trials consisted of incubation of untreated rolled barley grain in cows fed CTR or TRT diets and of incubation of 3 different substrates including CTR or barley grain steeped in 0.5% or 1.0% LA (TRT1 and TRT2, respectively) up to 72 h in the rumen. Results of the in vivo trial indicated that cows fed the TRT diet had greater rumen pH during most intensive fermentation phases at 10 and 12 h post-feeding. The latter effect was associated with a shorter duration in which rumen pH was below 5.8 for cows fed the TRT diet (2.4 h) compared with CTR diet (3.9 h). Furthermore, cows fed the TRT diet had lower concentrations of volatile fatty acids at 2 and 4 h post-feeding. In addition, concentrations of preprandial volatile fatty acids were lower in the rumen fluid of cows fed the TRT diet. Results also showed that molar proportion of acetate was lower, whereas propionate tended to increase by feeding cows the TRT diet. Cows fed the TRT diet demonstrated greater rumen in situ lag time of substrate DM degradation and a tendency to lower the fractional degradation rate. Other in situ results indicated a quadratic effect of LA on the effective rumen degradability of substrates whereby the latter variable was decreased from CTR to TRT1 but increased for TRT2 substrate. Although the diet did not affect actual milk yield, fat-corrected milk, percentages of milk protein, and lactose and concentration of milk urea nitrogen, cows fed the TRT diet increased

  6. Detailed documentation of dynamic changes in flow depth and surface velocity during a large flood in a steep mountain stream

    NASA Astrophysics Data System (ADS)

    Asano, Yuko; Uchida, Taro

    2016-10-01

    Understanding the discharge capacity of channels and changes in hydraulic properties during large storms is essential for prediction of flash floods. However, such information is limited for steep mountain channels because of their complex nature and the lack of measured data. Thus, we obtained detailed water-level and surface-velocity data during large floods of a steep mountain channel, and documented how complex channel morphology affected water flow during large storms. We installed water-level and surface-velocity sensors at a cascade and at a pool that was 10 m downstream at the Aono Research Forest of the Arboricultural Research Institute of the University of Tokyo Forests in Japan. We successfully obtained 1-min interval data for a major storm with total precipitation of 288 mm that fell over 59 h and a maximum rainfall intensity of 25 mm/h. During the storm, height of the water surface from the deepest point of each cross section ranged from 0.35 to 1.57 m and surface velocity ranged from 0.35 to 4.15 m/s. As expected, the changes in flow depth, surface velocity, and velocity profiles were complex and differed even between the cascade and adjacent pool cross sections. Dramatic changes in flow conditions first occurred at the cascade when discharge increased to a certain point, when water suddenly stagnated at the foot of the cascade and submerged flow might have occurred. Thereafter, the water level increased remarkably but surface velocity and the velocity profile stayed almost constant at the cascade cross section. At the downstream pool, where most rocks were submerged at a mean water depth of 0.7 m, surface velocity suddenly increased dramatically and the velocity profile changed as very slow flow developed in the lower portion of the profile, while water levels increased only slightly. When the rainfall diminished, first, the surface velocity markedly declined, then the velocity profile returned to its original state at the pool, and then submerged

  7. NREL Spectrum of Innovation

    ScienceCinema

    None

    2016-07-12

    There are many voices calling for a future of abundant clean energy. The choices are difficult and the challenges daunting. How will we get there? The National Renewable Energy Laboratory integrates the entire spectrum of innovation including fundamental science, market relevant research, systems integration, testing and validation, commercialization and deployment. The innovation process at NREL is interdependent and iterative. Many scientific breakthroughs begin in our own laboratories, but new ideas and technologies come to NREL at any point along the innovation spectrum to be validated and refined for commercial use.

  8. Spectrum of wormholes

    SciTech Connect

    Hawking, S.W. Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW ); Page, D.N. Department of Physics, Pennsylvania State University, University Park, PA Theoretical Physics Institute, Department of Physics, University of Alberta, Edmonton, AB )

    1990-10-15

    Wormholes have been studied mainly in the semiclassical approximation as solutions of the classical Euclidean field equations. However, such solutions are rather special, and exist only for certain kinds of matter. On the other hand, one can represent wormholes in a more general manner as solutions of the Wheeler-DeWitt equation with appropriate boundary conditions. Minisuperspace models with massless minimal or conformal scalar fields have a discrete spectrum of these solutions. The Giddings-Strominger instanton solution corresponds to a sum of an infinite number of these solutions. Minisuperspace models with a massive scalar field also appear to have a discrete spectrum of such solutions, whose asymptotic form is given.

  9. Improving VHF Spectrum Utilization

    NASA Technical Reports Server (NTRS)

    Andro, Monty; Orr, Richard; Foore, Larry; Sheehe, Charles; Freeman, Mark; Nguyen, Thanh; Bretmersky, Steven; Laberge, Chuck; Buchanan, David

    2004-01-01

    Limited VHF communications system capacity and increasing air traffic results in congestion of the aviation VHF spectrum. The voice communications errors and delayed channel access create system congestion and air traffic delays. Regulatory subdivision of bands for specific functions limits flexibility in the frequency usage. The objective of this viewgraph presentation is to identify near/mid/far term technologies to improve the performance and spectrum efficiency of current and emerging VHF communications systems. Select technologies with the highest potential, perform research and development to bring them to implementation stage.

  10. NREL Spectrum of Innovation

    SciTech Connect

    2011-01-01

    There are many voices calling for a future of abundant clean energy. The choices are difficult and the challenges daunting. How will we get there? The National Renewable Energy Laboratory integrates the entire spectrum of innovation including fundamental science, market relevant research, systems integration, testing and validation, commercialization and deployment. The innovation process at NREL is interdependent and iterative. Many scientific breakthroughs begin in our own laboratories, but new ideas and technologies come to NREL at any point along the innovation spectrum to be validated and refined for commercial use.

  11. Flat-spectrum speech.

    PubMed

    Schroeder, M R; Strube, H W

    1986-05-01

    Flat-spectrum stimuli, consisting of many equal-amplitude harmonics, produce timbre sensations that can depend strongly on the phase angles of the individual harmonics. For fundamental frequencies in the human pitch range, many realizable timbres have vowel-like perceptual qualities. This observation suggests the possibility of constructing intelligible voiced speech signals that have flat-amplitude spectra. This paper describes a successful experiment of creating several different diphthongs by judicious choice of the phase angles of a flat-spectrum waveform. A possible explanation of the observed vowel timbres lies in the dependence of the short-time amplitude spectra on phase changes.

  12. Quenched hadron spectrum of QCD

    SciTech Connect

    Kim, Seyong.

    1992-12-01

    We calculate hadron spectrum of quantum chromodynamics without dynamical fermions on a 32[sup 3] [times] 64 lattice volume at [beta] = 6.5. Using two different wall sources of staggered fermion whose mass is 0.01, 0.005 and 0.0025 under the background gauge configurations, we extract local light hadron masses and the [triangle] masses and compare these hadron masses with those from experiments. The numerical simulation is executed on the Intel Touchstone Delta computer. We employ multihit metropolis algorithm with over-relaxation method steps to update gauge field configuration and gauge field configuration are collected at every 1000 sweeps. After the gauge field configuration is fixed to Coulomb gauge, the conjugate gradient method is used for Dirac matrix inversion.

  13. Quenched hadron spectrum of QCD

    SciTech Connect

    Kim, Seyong

    1992-12-01

    We calculate hadron spectrum of quantum chromodynamics without dynamical fermions on a 32{sup 3} {times} 64 lattice volume at {beta} = 6.5. Using two different wall sources of staggered fermion whose mass is 0.01, 0.005 and 0.0025 under the background gauge configurations, we extract local light hadron masses and the {triangle} masses and compare these hadron masses with those from experiments. The numerical simulation is executed on the Intel Touchstone Delta computer. We employ multihit metropolis algorithm with over-relaxation method steps to update gauge field configuration and gauge field configuration are collected at every 1000 sweeps. After the gauge field configuration is fixed to Coulomb gauge, the conjugate gradient method is used for Dirac matrix inversion.

  14. Spectrum-RG astrophysical project

    NASA Astrophysics Data System (ADS)

    Pavlinsky, M.; Sunyaev, R.; Churazov, E.; Vikhlinin, A.; Sazonov, S.; Revnivtsev, M.; Arefiev, V.; Lapshov, I.; Akimov, V.; Levin, V.; Buntov, M.; Semena, N.; Grigorovich, S.; Babyshkin, V.; Predehl, P.; Hasinger, G.; Böhringer, H.; Schmitt, J.; Santangelo, A.; Schwope, A.; Wilms, J.

    2009-08-01

    The Spectrum-Roentgen-Gamma mission will be launched in the 2012 year into a L2 orbit with Soyuz launcher and Fregat buster from Baikonur. The mission will conduct all-sky survey with X-ray mirror telescopes eROSITA and ART-XC up to 11 keV. It will allow detection of about 100 thousand clusters of galaxies and discovery large scale Universe structure. It will also discover all obscured accreting Black Holes in nearby galaxies and many (about 3 millions) new distant AGN. Then it is planned to observe dedicated sky regions with high sensitivity and thereafter to perform follow-up pointed observations of selected sources.

  15. A Compact X-Ray Source in the Radio Pulsar-wind Nebula G141.2+5.0

    NASA Astrophysics Data System (ADS)

    Reynolds, Stephen P.; Borkowski, Kazimierz J.

    2016-01-01

    We report the results of a 50 ks Chandra observation of the recently discovered radio object G141.2+5.0, presumed to be a pulsar-wind nebula. We find a moderately bright unresolved X-ray source that we designate CXOU J033712.8 615302 coincident with the central peak radio emission. An absorbed power-law fit to the 241 counts describes the data well, with absorbing column {N}H=6.7(4.0,9.7)× {10}21 cm-2 and photon index {{Γ }}=1.8(1.4,2.2). For a distance of 4 kpc, the unabsorbed luminosity between 0.5 and 8 keV is {1.7}-0.3+0.4× {10}32 erg s-1 (90% confidence intervals). Both LX and Γ are quite typical of pulsars in PWNe. No extended emission is seen; we estimate a conservative 3σ upper limit to the surface brightness of any X-ray PWN near the point source to be 3× {10}-17 erg cm-2 s-1 arcsec-2 between 0.5 and 8 keV, assuming the same spectrum as the point source; for a nebula of diameter 13\\prime\\prime , the flux limit is 6% of the flux of the point source. The steep radio spectrum of the PWN (α ˜ -0.7), if continued to the X-ray without a break, predicts {L}{{X}} {{(nebula)}}˜ 1× {10}33 erg s-1, so additional spectral steepening between radio and X-rays is required, as is true of all known PWNe. The high Galactic latitude gives a z-distance of 350 pc above the Galactic plane, quite unusual for a Population I object.

  16. On the interpretation of the geomagnetic energy spectrum

    USGS Publications Warehouse

    Benton, E.R.; Alldredge, L.R.

    1987-01-01

    Two recent high-degree magnetic energy spectra, based mostly on MAGSAT data, are compared and found to agree very well out to order and degree n = 15, but the spectrum remains somewhat uncertain for higher degrees. The hypothesis that a primary break in the slope of the spectrum, plotted semi-logarithmically, is due to a transition from dominance by core sources to dominance by crustal magnetization is tested. Simple arrays of dipoles and current loops are found whose combined fields fit the spectrum. Two distinctly different ranges of source depth are found to be adequate. Because one range is shallow and the other deep, the hypothesis is supported. ?? 1987.

  17. Illuminant spectrum estimation at a pixel.

    PubMed

    Ratnasingam, Sivalogeswaran; Hernández-Andrés, Javier

    2011-04-01

    In this paper, an algorithm is proposed to estimate the spectral power distribution of a light source at a pixel. The first step of the algorithm is forming a two-dimensional illuminant invariant chromaticity space. In estimating the illuminant spectrum, generalized inverse estimation and Wiener estimation methods were applied. The chromaticity space was divided into small grids and a weight matrix was used to estimate the illuminant spectrum illuminating the pixels that fall within a grid. The algorithm was tested using a different number of sensor responses to determine the optimum number of sensors for accurate colorimetric and spectral reproduction. To investigate the performance of the algorithm realistically, the responses were multiplied with Gaussian noise and then quantized to 10 bits. The algorithm was tested with standard and measured data. Based on the results presented, the algorithm can be used with six sensors to obtain a colorimetrically good estimate of the illuminant spectrum at a pixel.

  18. Velocity shear, turbulent saturation, and steep plasma gradients in the scrape-off layer of inner-wall limited tokamaks

    NASA Astrophysics Data System (ADS)

    Halpern, F. D.; Ricci, P.

    2017-03-01

    The narrow power decay-length ({λq} ), recently found in the scrape-off layer (SOL) of inner-wall limited (IWL) discharges in tokamaks, is studied using 3D, flux-driven, global two-fluid turbulence simulations. The formation of the steep plasma profiles is found to arise due to radially sheared \\mathbf{E}× \\mathbf{B} poloidal flows. A complex interaction between sheared flows and parallel plasma currents outflowing into the sheath regulates the turbulent saturation, determining the transport levels. We quantify the effects of sheared flows, obtaining theoretical estimates in agreement with our non-linear simulations. Analytical calculations suggest that the IWL {λq} is roughly equal to the turbulent correlation length.

  19. Velocity shear, turbulent saturation, and steep plasma gradients in the scrape-off layer of inner-wall limited tokamaks

    SciTech Connect

    Halpern, Federico D.; Ricci, Paolo

    2016-12-19

    The narrow power decay-length (λq), recently found in the scrape-off layer (SOL) of inner wall limited (IWL) discharges in tokamaks, is studied using 3D, flux-driven, global two fluid turbulence simulations. The formation of the steep plasma profiles is found to arise due to radially sheared E×B poloidal flows. A complex interaction between sheared flows and parallel plasma currents outflowing into the sheath regulates the turbulent saturation, determining the transport levels. We quantify the effects of sheared flows, obtaining theoretical estimates in agreement with our non-linear simulations. As a result, analytical calculations suggest that the IWL λq is roughly equal to the turbulent correlation length.

  20. A Binary Tunnel Field Effect Transistor with a Steep Sub-threshold Swing and Increased ON Current

    NASA Astrophysics Data System (ADS)

    Asra, Ram; Murali, Kota V. R. M.; Ramgopal Rao, V.

    2010-12-01

    A variant tunnel field effect transistor structure called the binary tunnel field effect transistor (BTFET) for low voltage and near ideal switching characteristics is proposed. The BTFET relies on a binary tunneling distance (HIGH and LOW) for its operation to achieve a steep sub-threshold swing with a predicted range of 5 mV/dec. The transition of tunneling distance from HIGH to LOW state is a step-function of the gate voltage with the threshold voltage as a transition voltage. BTFET has a high on-current due to the high gate electric field and a large tunneling cross section area. An orientation dependent non-local band-to-band tunneling model was used to analyze the DC characteristics of the device.

  1. Velocity shear, turbulent saturation, and steep plasma gradients in the scrape-off layer of inner-wall limited tokamaks

    DOE PAGES

    Halpern, Federico D.; Ricci, Paolo

    2016-12-19

    The narrow power decay-length (λq), recently found in the scrape-off layer (SOL) of inner wall limited (IWL) discharges in tokamaks, is studied using 3D, flux-driven, global two fluid turbulence simulations. The formation of the steep plasma profiles is found to arise due to radially sheared E×B poloidal flows. A complex interaction between sheared flows and parallel plasma currents outflowing into the sheath regulates the turbulent saturation, determining the transport levels. We quantify the effects of sheared flows, obtaining theoretical estimates in agreement with our non-linear simulations. As a result, analytical calculations suggest that the IWL λq is roughly equal tomore » the turbulent correlation length.« less

  2. Generation of solar spectrum by using LEDs

    NASA Astrophysics Data System (ADS)

    Lu, Pengzhi; Yang, Hua; Pei, Yanrong; Li, Jing; Xue, Bin; Wang, Junxi; Li, Jinmin

    2016-09-01

    Light emitting diode (LED) has been recognized as an applicable light source for indoor and outdoor lighting, city beautifying, landscape facilities, and municipal engineering etc. Conventional LED has superior characteristics such as long life time, low power consumption, high contrast, and wide viewing angle. Recently, LED with high color-rendering index and special spectral characteristics has received more and more attention. This paper is intended to report a solar spectrum simulated by multichip LED light source. The typical solar spectrum of 5500k released by CIE was simulated as a reference. Four types of LEDs with different spectral power distributions would be used in the LED light source, which included a 430nm LED, a 480nm LED, a 500nm LED and a white LED. In order to obtain better simulation results, the white LED was achieved by a 450nm LED chip with the mixture of phosphor. The phosphor combination was prepared by mixing green phosphor, yellow phosphor and red phosphor in a certain proportion. The multichip LED light source could provide a high fidelity spectral match with the typical solar spectrum of 5500k by adjusting injection current to each device. The luminous flux, CIE chromaticity coordinate x, y, CCT, and Ra were 104.7 lm, 0.3337, 0.3681, 5460K, and 88.6, respectively. Because of high color-rendering index and highly match to the solar spectrum, the multichip LED light source is a competitive candidate for applications where special spectral is required, such as colorimetric measurements, visual inspection, gemstone identification and agriculture.

  3. Bedload Transport Rates and Flux Patterns in a Steep Montane Tropical River - Rio Pacuare, Costa Rica

    NASA Astrophysics Data System (ADS)

    Lind, P.; Fonstad, M. A.; McDowell, P. F.

    2015-12-01

    Humid tropical montane rivers convey large magnitude floods that have the potential to mobilize boulder-sized bed material multiple times during a year. In the montane reaches of the Rio Pacuare active boulder deposits with surface areas of up to 300 x 75 meters influence channel form throughout this otherwise hillslope/bedrock confined river. Therefore, rate of bedload sediment flux occurring within and between river segments and reaches provides insight into the geomorphic sensitivity of the system. The study area (78 km) is divided into five river segments based on channel slope and form. The intense discharge regimes of the Rio Pacuare are off-set by the plentiful sediment inputs sourced from upstream, tributaries, and hillslopes, resulting in a system that is predominantly transport-limited. This research presents bedload sediment transport rates and annual yields calculated at seven representative field sites distributed throughout the study area. Results indicate that the D50 and D84 grain-size fractions are mobilized frequently (annual rate is dependent on timing and frequency of precipitation events). Results also indicate that connectivity between river segments ranges from moderate to high, depending most directly on channel slope. This work utilized a unique mix of traditional grain-size analysis and sediment transport models combined with repeat photogrammetric Structure from Motion (SfM) surveys done pre and post flood event to verify grain size mobilization through high-resolution, 3-D modeling.

  4. Properties of Particle Size Distribution from Milled White Nixtamalized Corn Kernels as a Function of Steeping Time

    PubMed Central

    Fernández-Muñoz, J. L.; Zapata-Torrez, M.; Márquez-Herrera, A.; Sánchez-Sinencio, F.; Mendoza-Álvarez, J. G.; Meléndez-Lira, M.; Zelaya-Ángel, O.

    2016-01-01

    This paper focuses on the particle size distribution (PSD) changes during nixtamalized corn kernels (NCK) as a function of the steeping time (ST). The process to obtain powder or corn flour from NCK was as follows: (i) the NCK with different STs were wet-milled in a stone mill, (ii) dehydrated by a Flash type dryer, and (iii) pulverized with a hammer mill and sieved with a 20 mesh. The powder was characterized by measuring the PSD percentage, calcium percentage (CP), peak viscosity at 90°C (PV), and crystallinity percentage (CP). The PSD of the powder as a function of ST was determined by sieving in Ro-TAP equipment. By sieving, five fractions of powder were obtained employing meshes 30, 40, 60, 80, and 100. The final weight of the PSD obtained from the sieving process follows a Gaussian profile with the maximum corresponding to the average particle obtained with mesh 60. The calcium percentage as a function of ST follows a behavior similar to the weight of the PSD. The study of crystallinity versus the mesh number shows that it decreases for smaller mesh number. A similar behavior is observed as steeping time increases, except around ST = 8 h where the gelatinization of starch is observed. The trend of increasing viscosity values of the powder samples occurs when increasing ST and decreasing particle size. The ST significantly changes the crystallinity and viscosity values of the powder and, in both cases, a minimum value is observed in the region 7–9 h. The experimental results show that the viscosity increases (decreases) if the particle size decreases (increases). PMID:27375921

  5. Differences in hydrological responses for different vegetation types on a steep slope on the Loess Plateau, China

    NASA Astrophysics Data System (ADS)

    Duan, Liangxia; Huang, Mingbin; Zhang, Luodan

    2016-06-01

    Extensive vegetation restoration practices have been implemented to control soil erosion on the Loess Plateau, China. However, no strict guidelines are available to determine the most suitable plant species for vegetation restoration within a given area. The objective of this study was to quantify the changes of each component (soil water storage, surface runoff, and actual evapotranspiration) of a water balance model and soil loss over time under eight different vegetation types, and to further determine the optimal vegetation type for soil and water conservation and sustainable ecological restoration on the steep slopes (>25°) on the Loess Plateau. The results indicated that vegetation type substantially affected soil water storage and that the greatest soil water storage in both the shallow (0-2 m) and the deep soil layers (2-5 m) occurred under Bothriochloa ischaemum L. (BOI). Vegetation type also affected surface runoff and soil losses. The most effective vegetation types for reducing soil erosion were BOI and Sea-buckthorn (Hippophae rhamnoides L.), while Chinese pine (Pinus tabulaeformis Carr.) and Chinese pine + Black locust (Robinia pseudoacacia L.) were the most ineffective types. Soil water dynamics and evapotranspiration varied considerably among the different vegetation types. A soil water surplus was only found under BOI, while insufficient water replenishment existed under the other seven vegetation types. The higher water consumption rates of the seven vegetation types could result in soil desiccation, which could lead to severe water stresses that would adversely affect plant growth. This study suggested that both vegetation type and its effect on controlling soil erosion should be considered when implementing vegetation restoration and that BOI should be highly recommended for vegetation restoration on the steep slopes of the Loess Plateau. A similar approach to the one used in this study could be applied to other regions of the world confronted

  6. Single-centre experience of retroperitoneoscopic approach in urology with tips to overcome the steep learning curve

    PubMed Central

    Srivastava, Aneesh; Sureka, Sanjoy Kumar; Vashishtha, Saurabh; Agarwal, Shikhar; Ansari, Md Saleh; Kumar, Manoj

    2016-01-01

    CONTEXT: The retroperitoneoscopic or retroperitoneal (RP) surgical approach has not become as popular as the transperitoneal (TP) one due to the steeper learning curve. AIMS: Our single-institution experience focuses on the feasibility, advantages and complications of retroperitoneoscopic surgeries (RS) performed over the past 10 years. Tips and tricks have been discussed to overcome the steep learning curve and these are emphasised. SETTINGS AND DESIGN: This study made a retrospective analysis of computerised hospital data of patients who underwent RP urological procedures from 2003 to 2013 at a tertiary care centre. PATIENTS AND METHODS: Between 2003 and 2013, 314 cases of RS were performed for various urological procedures. We analysed the operative time, peri-operative complications, time to return of bowel sound, length of hospital stay, and advantages and difficulties involved. Post-operative complications were stratified into five grades using modified Clavien classification (MCC). RESULTS: RS were successfully completed in 95.5% of patients, with 4% of the procedures electively performed by the combined approach (both RP and TP); 3.2% required open conversion and 1.3% were converted to the TP approach. The most common cause for conversion was bleeding. Mean hospital stay was 3.2 ± 1.2 days and the mean time for returning of bowel sounds was 16.5 ± 5.4 h. Of the patients, 1.4% required peri-operative blood transfusion. A total of 16 patients (5%) had post-operative complications and the majority were grades I and II as per MCC. The rates of intra-operative and post-operative complications depended on the difficulty of the procedure, but the complications diminished over the years with the increasing experience of surgeons. CONCLUSION: Retroperitoneoscopy has proven an excellent approach, with certain advantages. The tips and tricks that have been provided and emphasised should definitely help to minimise the steep learning curve. PMID:27073300

  7. Adaptive traits are maintained on steep selective gradients despite gene flow and hybridization in the intertidal zone.

    PubMed

    Zardi, Gerardo I; Nicastro, Katy R; Canovas, Fernando; Costa, Joana Ferreira; Serrão, Ester A; Pearson, Gareth A

    2011-01-01

    Gene flow among hybridizing species with incomplete reproductive barriers blurs species boundaries, while selection under heterogeneous local ecological conditions or along strong gradients may counteract this tendency. Congeneric, externally-fertilizing fucoid brown algae occur as distinct morphotypes along intertidal exposure gradients despite gene flow. Combining analyses of genetic and phenotypic traits, we investigate the potential for physiological resilience to emersion stressors to act as an isolating mechanism in the face of gene flow. Along vertical exposure gradients in the intertidal zone of Northern Portugal and Northwest France, the mid-low shore species Fucus vesiculosus, the upper shore species Fucus spiralis, and an intermediate distinctive morphotype of F. spiralis var. platycarpus were morphologically characterized. Two diagnostic microsatellite loci recovered 3 genetic clusters consistent with prior morphological assignment. Phylogenetic analysis based on single nucleotide polymorphisms in 14 protein coding regions unambiguously resolved 3 clades; sympatric F. vesiculosus, F. spiralis, and the allopatric (in southern Iberia) population of F. spiralis var. platycarpus. In contrast, the sympatric F. spiralis var. platycarpus (from Northern Portugal) was distributed across the 3 clades, strongly suggesting hybridization/introgression with both other entities. Common garden experiments showed that physiological resilience following exposure to desiccation/heat stress differed significantly between the 3 sympatric genetic taxa; consistent with their respective vertical distribution on steep environmental clines in exposure time. Phylogenetic analyses indicate that F. spiralis var. platycarpus is a distinct entity in allopatry, but that extensive gene flow occurs with both higher and lower shore species in sympatry. Experimental results suggest that strong selection on physiological traits across steep intertidal exposure gradients acts to maintain

  8. Spread Spectrum Frequency Management

    DTIC Science & Technology

    1989-06-01

    theoretically predicted behavior of the new system. Thp experimental program must include field tests in real propagation and interference environments...technological developments and without adequate overall knowledge of propagation characteristics or of other important uses that might require... propagation characteristics at the different frequency levels. The history of major spectrum allocations is then a 7 record of decisions primarily

  9. Stellar Spectrum Synthesizer

    ERIC Educational Resources Information Center

    Landegren, G. F.

    1975-01-01

    Describes a device which employs two diffraction gratings and three or four simple lenses to produce arbitrary absorption or emission spectra that may be doppler shifted and spectroscopically examined by students some distance away. It may be regarded as a sort of artificial star whose spectrum may be analyzed as an undergraduate laboratory…

  10. The Frequency Spectrum Radio.

    ERIC Educational Resources Information Center

    Howkins, John, Ed.

    1979-01-01

    This journal issue focuses on the frequency spectrum used in radio communication and on the World Administrative Radio Conference, sponsored by the International Telecommunication Union, held in Geneva, Switzerland, in the fall of 1979. Articles describe the World Administrative Radio Conference as the most important radio communication conference…

  11. Battlefield spectrum management

    NASA Astrophysics Data System (ADS)

    Sivakumar, C.

    1997-06-01

    Modern tactical communications systems rely on radios to support network and user connectivity. One of the challenges for network planners and managers is to make best use of scarce and vulnerable frequency spectrum resources to support the communication needs of war fighters. With the wide variety of Iris radio types typically to be deployed in the battlefield (ranging from high frequency to super high frequency), a comprehensive suite of tools is necessary to ensure that frequency interference is kept minimum. Without a sophisticated frequency spectrum management system, the most advanced tactical communications systems could be rendered useless, jeopardizing human life and national security. For these reasons, it is important to develop an Iris wide battlefield spectrum management capability that takes full advantage of current frequency spectrum management research and development (R&D), related tools, and supporting technology for assigning frequencies. This session briefly describes various assignment strategies being adopted in the Iris BFSM for overcoming cosite/collocated/farsite interferences along with the propagation models [from high frequency (HF) to super high frequency (SHF)] used for the assignment of frequencies. Also a brief thread outlining the process for generating frequency allocation/assignment request and analysis of frequency interference is discussed.

  12. Steep Decline and Cessation in Seed Dispersal by Myrmica rubra Ants

    PubMed Central

    2015-01-01

    Myrmecochorous diaspores bear a nutrient-rich appendage, the elaiosome, attractive to ant workers that retrieve them into the nest, detach the elaiosome and reject the seed intact. While this interaction is beneficial for the plant partner by ensuring its seed dispersal, elaiosome consumption has various effects −positive, negative or none − on ants’ demography and survival, depending on both the ant/plant species involved. In this context, the contribution of ants to seed dispersal strongly varies according to the ant/plant pairs considered. In this paper, we investigate whether the dynamics of myrmecochory also vary on a temporal scale, for a given pair of partners: Myrmica rubra ants and Viola odorata seeds. During their first encounter with seeds, ants collect all the diaspores and eat the majority of elaiosomes. Both the harvesting effort and the elaiosome consumption decline when seeds are offered on the next week and completely cease for the following weeks. This is related to a decrease in the number of foragers reaching the food source, as well as to a reduced probability for an ant contacting a seed to retrieve it. Seed retrieval is not reactivated after seven weeks without any encounter with V. odorata seeds. By contrast, naive ant colonies only fed with fruit flies do not show a decline of prey harvesting of which the speed of retrieval even increases over the successive weeks. Myrmecochory may thus be labile at the scale of a fruiting season due to the ability of ants to steeply tune and cease for several months the harvesting of these seemingly poorly rewarding items and to maintain cessation of seed exploitation. The present study emphasizes the importance of a long-lasting follow up of the myrmecochory process, to assess the stability of this ant-plant partnership and to identify mechanisms of adaptive harvesting in ants. PMID:26414161

  13. Steep Decline and Cessation in Seed Dispersal by Myrmica rubra Ants.

    PubMed

    Bologna, Audrey; Detrain, Claire

    2015-01-01

    Myrmecochorous diaspores bear a nutrient-rich appendage, the elaiosome, attractive to ant workers that retrieve them into the nest, detach the elaiosome and reject the seed intact. While this interaction is beneficial for the plant partner by ensuring its seed dispersal, elaiosome consumption has various effects -positive, negative or none - on ants' demography and survival, depending on both the ant/plant species involved. In this context, the contribution of ants to seed dispersal strongly varies according to the ant/plant pairs considered. In this paper, we investigate whether the dynamics of myrmecochory also vary on a temporal scale, for a given pair of partners: Myrmica rubra ants and Viola odorata seeds. During their first encounter with seeds, ants collect all the diaspores and eat the majority of elaiosomes. Both the harvesting effort and the elaiosome consumption decline when seeds are offered on the next week and completely cease for the following weeks. This is related to a decrease in the number of foragers reaching the food source, as well as to a reduced probability for an ant contacting a seed to retrieve it. Seed retrieval is not reactivated after seven weeks without any encounter with V. odorata seeds. By contrast, naive ant colonies only fed with fruit flies do not show a decline of prey harvesting of which the speed of retrieval even increases over the successive weeks. Myrmecochory may thus be labile at the scale of a fruiting season due to the ability of ants to steeply tune and cease for several months the harvesting of these seemingly poorly rewarding items and to maintain cessation of seed exploitation. The present study emphasizes the importance of a long-lasting follow up of the myrmecochory process, to assess the stability of this ant-plant partnership and to identify mechanisms of adaptive harvesting in ants.

  14. Infrared-faint radio sources remain undetected at far-infrared wavelengths. Deep photometric observations using the Herschel Space Observatory

    NASA Astrophysics Data System (ADS)

    Herzog, A.; Norris, R. P.; Middelberg, E.; Spitler, L. R.; Leipski, C.; Parker, Q. A.

    2015-08-01

    Context. Showing 1.4 GHz flux densities in the range of a few to a few tens of mJy, infrared-faint radio sources (IFRS) are a type of galaxy characterised by faint or absent near-infrared counterparts and consequently extreme radio-to-infrared flux density ratios up to several thousand. Recent studies showed that IFRS are radio-loud active galactic nuclei (AGNs) at redshifts ≳2, potentially linked to high-redshift radio galaxies (HzRGs). Aims: This work explores the far-infrared emission of IFRS, providing crucial information on the star forming and AGN activity of IFRS. Furthermore, the data enable examining the putative relationship between IFRS and HzRGs and testing whether IFRS are more distant or fainter siblings of these massive galaxies. Methods: A sample of six IFRS was observed with the Herschel Space Observatory between 100 μm and 500 μm. Using these results, we constrained the nature of IFRS by modelling their broad-band spectral energy distribution (SED). Furthermore, we set an upper limit on their infrared SED and decomposed their emission into contributions from an AGN and from star forming activity. Results: All six observed IFRS were undetected in all five Herschel far-infrared channels (stacking limits: σ = 0.74 mJy at 100 μm, σ = 3.45 mJy at 500 μm). Based on our SED modelling, we ruled out the following objects to explain the photometric characteristics of IFRS: (a) known radio-loud quasars and compact steep-spectrum sources at any redshift; (b) starburst galaxies with and without an AGN and Seyfert galaxies at any redshift, even if the templates were modified; and (c) known HzRGs at z ≲ 10.5. We find that the IFRS analysed in this work can only be explained by objects that fulfil the selection criteria of HzRGs. More precisely, IFRS could be (a) known HzRGs at very high redshifts (z ≳ 10.5); (b) low-luminosity siblings of HzRGs with additional dust obscuration at lower redshifts; (c) scaled or unscaled versions of Cygnus A at any

  15. [Backscattering spectrum analysis of nonspheroid soot particle].

    PubMed

    Xing, Jian; Sun, Xiao-gang; Yuan, Gui-bin; Qi, Xu; Tang, Hong

    2010-08-01

    In the process of measuring soot concentration and grain diameter, the backscattering spectrum of soot particle model was calculated to ascertain and analyze main effective factor of backscattering intensity. In the present paper, ellipsoid, column and generalized Chebyshev, three nonspheroid models, were selected according to micrograph of practical soot particle, which aims to simulate practical soot particle with equivalent diameter of about 1 microm. T-matrix method was used to calculate backscattering spectrum of the three nonspheriod models, and the main effective factor curves of intensity were obtained, too. Both numerical computer simulations and experimental results illustrate that nonspheroid particle backscattering intensity is stronger than that of spheroid particle in the visible/infrared spectrum band, especially for generalized Chebyshev model, whose backscattering intensity can be even 3.5 times higher than that of forward scattering. Meanwhile, the absorbency non-spheroid particle (complex refractive index m = 1.57 - 0.56i) backscattering intensity is stronger than that of non-absorbency nonspheriod particle (complex refractive index m = 1.57 - 0.001i). Furthermore, with the increase in particle equivalent radius, the light source wavelength also needs to be increase to obtain more light intensity information. The backscattering light spectrum information provides a reasonable basis for selecting light source and measure angle.

  16. Improved techniques for monitoring the HF spectrum

    NASA Astrophysics Data System (ADS)

    Giesbrecht, James E.; Clarke, Russell; Abbott, Derek

    2004-03-01

    A critical review of contemporary papers on modulation recognition, signal separation, and Single Station Location (SSL) is described in the context of High-Frequency (HF) radio-communications. High-frequency communications is undergoing resurgence despite advances in long-range satellite communication systems. Defense agencies are using the HF spectrum for backup communications as well as for spectrum surveillance applications. Spectrum management organizations are monitoring the HF spectrum to control and enforce licensing. This type of activity usually requires a system that is able to determine the location of a source of transmissions, separate valid signals from interferers and noise, and characterize signals-of-interest (SOI). The immediate aim is to show that commercial-off-the-shelf (COTS) equipment can be used to locate HF transmission sources, enhance SOIs and reject interference, and recognize signal types. The described work on single-station-location (SSL), signal separation, and modulation recognition is contributing to these goals. This paper describes the overall objectives and some of the disadvantages and benefits of various schemes for single-station-location (SSL), signal separation, and modulation recognition. It also proposes new approaches that may relieve shortcomings of existing methods -- including selection of benchmarks or modulations for various transmission scenarios and propagation modes, and use of multiple digital receivers or compression techniques to improve modulation recognition, signal separation, and location of HF emitters.

  17. Dryout of a Steep Hillslope During Periods of Extended Seasonal Drought

    NASA Astrophysics Data System (ADS)

    Salve, R.; Rempe, D. M.; Dietrich, W. E.

    2011-12-01

    Studies investigating the mechanics of hillslope hydrology typically explore processes that are prominent as precipitation is transformed to runoff. In seasonally water-stressed environments such as arid Mediterranean climates, re-distribution of subsurface moisture during extended periods of seasonal drought is also a significant, though often ignored, component of the hydrologic system. During this period, ground moisture sustains vegetation for upwards of 6 months without replenishment, and researchers have suggested that weathered bedrock is a critical source of water during the summer drought. We have monitored a 4000 m2 hillslope in the Angelo Coast Range Reserve along the Eel River in Northern California to explore hydrologic processes. Since September 2007, devices for tracking saturation changes in soil and rock (e.g., TDR probes, Electrical Resistance Probes, Neutron logging), and climate attributes have been installed throughout the catchment. In addition, 7 deep wells up to nearly 30 m depth were drilled across the hillslope and water levels have been continuously monitored since then. Drilling revealed a thin (< 0.3 m) soil mantle overlying a fractured mudstone weathering profile that extends up to 20 m near the ridgetop and tapers downslope towards a bedrock lined channel named Elder Creek. Baseflow sustains Elder Creek year round. Vegetation at the site is dominated by Pseudostuga menziesii (Douglas Fir), Arbutus menziesii (Madrone), Quercus wislizeni (Interior live oak), Umbellularia californica (California bay), Notholithocarpus densiflorus (Tan-bark oak) and Sequoia sempervirens (Redwood) trees. Average rainfall is about 2 m with nearly all of it occurring between November and April. For approximately six months during the warm summer, there is no recordable precipitation. We have observed that during the long precipitation-free period, there is significant reduction in the amount of water retained in the shallow soil/weathered rock profile, and

  18. Influences of edges and steep slopes in 3D interference and confocal microscopy

    NASA Astrophysics Data System (ADS)

    Xie, Weichang; Hagemeier, Sebastian; Woidt, Carsten; Hillmer, Harmut; Lehmann, Peter

    2016-04-01

    Optical measurement techniques are widely applied in high-resolution contour, topography and roughness measurement. In this context vertical scanning white-light interferometers and confocal microscopes have become mature instruments over the last decades. The accuracy of measurement results is highly related not only to the type and physical properties of the measuring instruments, but also to the measurement object itself. This contribution focuses on measurement effects occurring at edges and height steps using white-light interferometers of different numerical apertures. If the edge is perfectly perpendicular, batwing effects appear at height steps. These batwings show maximum height if the height-to-wavelength-ratio (HWR) is about one forth or three forth, and they disappear if the HWR value is about an integer multiple of one half. The wavelength that is relevant in this context is the effective wavelength, i.e. the center wavelength of the illuminating light multiplied by a correction factor known as the numerical aperture correction. However, in practice the edges are usually not perfectly perpendicular. In this case, the measurement results depend also on the derivative of the surface height function and they may differ from theory and the prediction according to the HWR value. Measurements of such steps show systematical effects depending on the lateral resolution of the instrument. In this context, a Linnik interferometer with a magnification of 100x and NA = 0.9 is used to characterize the three dimensional topography of more or less rectangular calibration specimens and quasi-perpendicular structures produced by the nanoimprint technology. The Linnik interferometer is equipped with LED light sources emitting at different wavelengths, so that the HWR value can be changed. This is possible since the high NA objective lenses show a rather limited depth of focus such that the temporal coherence gating may be replaced by focal gating in this particular

  19. Effects of ongoing glacier retreat on steep valley-side drift slopes in the upper Bødalen valley, western Norway

    NASA Astrophysics Data System (ADS)

    Laute, Katja; Beylich, Achim A.; Oppikofer, Thierry

    2013-04-01

    The general pattern and dominant trend of today's mountain glaciers worldwide is a retreat of glacier fronts, indicating a significant volume decrease. Negative glacier net balances have been recorded for all Scandinavian glaciers after 1999. The ongoing glacier retreat enlarges freshly exposed proglacial areas which are characterized by e.g. comparably higher intensities of denudational slope processes and higher sediment availability. This study focuses on influences of rapid glacier regression on contemporary surface processes acting on steep valley-side drift slopes in a characteristic steep, parabolic-shaped and glacier-fed valley (Bødalen,) located on the western side of the Jostedalsbreen ice cap in western Norway. The Bødalsbreen is one of the glaciers with the highest retreat rate in entire Norway. Since the Little Ice Age (LIA) glacier maximum advance (1750) the glacier retreated ca. 1.500 m, including 65 m of retreat within the period of 2001 to 2010. Due to this retreat large areas of unstable hillslopes covered by glacial deposits from the LIA lateral moraines have been exposed. A combination of high resolution terrestrial laser scanning (TLS) and a designed monitoring program has been applied to a selected hillslope site on the eastern flank of the Bødalsbreen. Three sequential terrestrial laser scans have been acquired in the summers of 2010, 2011 and 2012. The analysis of the three series of the high resolution point clouds enables (i) the detection of unstable slope areas, (ii) areas characterized primarily by erosion or deposition processes and (iii) to quantify volumes of mass transfers at the scanned site. The results from the TLS measurements are combined with the results from the monitoring program (installations in operation since 2009) which includes remote cameras for monitoring rapid mass movement events (avalanches, slush- and debris flows), stone tracer lines for measuring surface movements as well as temperature loggers both in rock

  20. Hydrologic behavior of a steep forested slope prone to shallow landsliding

    NASA Astrophysics Data System (ADS)

    Berti, Matteo; Simoni, Alessandro

    2015-04-01

    Over the past ten years, the frequency of debris flows in the Northern Apennines of Italy has significantly increased. Gravitational movements in the area are dominated by slow-moving landslides involving fine-grained soils and, to a lesser extent, by shallow slips in weathered arenaceous rocks. During the past 5 years, at least 20 debris flow events were triggered by exceptional rainfall events. Although no fatalities of injuries resulted from these landslides, the appearance of this new danger generated great concern among local communities. The Civil Protection Agency of the Emilia-Romagna region therefore decided to produce a debris flow susceptibility map to target high-risk zones and to help local authorities in emergency planning. This task, however, is particularly difficult due to the lack of historical data required to apply heuristic or statistical methods. In this context we installed a monitoring system on a representative slope in order to investigate the hydrologic response to rainfall and to support the choice of a suitable deterministic model. The selected slope is close to the village of Porretta Terme (Province of Bologna, Italy) at an elevation of 510 m asl. The slope has an inclination of about 30° and consists of a thin soil cover (0.5-1 thickness) lying over a fractured arenaceous bedrock. The soil is a well-graded sand with silt, gravel, cobbles, and weathered rock blocks. The slope is densely vegetated with grass, shrubs and mature trees. Part of the slope failed on the 30th November 2008 after a rainfall of 140 mm in 24 hours. A shallow slide of the soil mantle rapidly mobilized into debris flow leaving the bedrock exposed in the source area. The monitoring system is located on an unfailed slope close to the initiation area. The system consists of three stations aligned along the maximum slope at a distance of 15-20 m. Each station is equipped with: i) an open-standpipe piezometer installed near the soil-rock interface (1 m deep); ii

  1. ON THE ORIGIN OF THE 1/f SPECTRUM IN THE SOLAR WIND MAGNETIC FIELD

    SciTech Connect

    Verdini, Andrea; Grappin, Roland; Pinto, Rui

    2012-05-10

    We present a mechanism for the formation of the low-frequency 1/f magnetic spectrum based on numerical solutions of a shell-reduced MHD model of the turbulent dynamics inside the sub-Alfvenic solar wind. We assign reasonably realistic profiles to the wind speed and the density along the radial direction, and a radial magnetic field. Alfven waves of short periodicity (600 s) are injected at the base of the chromosphere, penetrate into the corona, and are partially reflected, thus triggering a turbulent cascade. The cascade is strong for the reflected wave while it is weak for the outward propagating waves. Reflection at the transition region recycles the strong turbulent spectrum into the outward weak spectrum, which is advected beyond the Alfvenic critical point without substantial evolution. There, the magnetic field has a perpendicular power-law spectrum with slope close to the Kolmogorov -5/3. The parallel spectrum is inherited from the frequency spectrum of large (perpendicular) eddies. The shape is a double power law with slopes of {approx_equal} - 1 and -2 at low and high frequencies, respectively, with the position of the break depending on the injected spectrum. We suggest that the double power-law spectrum measured by Helios at 0.3 AU, where the average magnetic field is not aligned with the radial (contrary to our assumptions), results from the combination of such different spectral slopes. At low frequency the parallel spectrum dominates with its characteristic 1/f shape, while at higher frequencies its steep spectral slope (-2) is masked by the more energetic perpendicular spectrum (slope -5/3).

  2. A geomagnetic field spectrum

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Estes, R. H.

    1982-01-01

    A spherical harmonic model of the earth's internal magnetic field of degree and order 23 is derived from selected Magsat data, and its power spectrum, computed with terms developed by Mauersberger (1956) and Lowes (1974), is found to exhibit a change of a slope at n = 14 which is interpreted as an indication that the core field dominates at values lower than 13 while the crust field dominates above a value of 15. The representations of the two portions of the spectrum obtained can be used to establish order-of-magnitude inaccuracies due to both crustal fields and the inability to observe core field wavelengths beyond n = 13, at which point they are obscured by the crustal field, in core field models.

  3. Spread spectrum image steganography.

    PubMed

    Marvel, L M; Boncelet, C R; Retter, C T

    1999-01-01

    In this paper, we present a new method of digital steganography, entitled spread spectrum image steganography (SSIS). Steganography, which means "covered writing" in Greek, is the science of communicating in a hidden manner. Following a discussion of steganographic communication theory and review of existing techniques, the new method, SSIS, is introduced. This system hides and recovers a message of substantial length within digital imagery while maintaining the original image size and dynamic range. The hidden message can be recovered using appropriate keys without any knowledge of the original image. Image restoration, error-control coding, and techniques similar to spread spectrum are described, and the performance of the system is illustrated. A message embedded by this method can be in the form of text, imagery, or any other digital signal. Applications for such a data-hiding scheme include in-band captioning, covert communication, image tamperproofing, authentication, embedded control, and revision tracking.

  4. Radio frequency spectrum management

    NASA Astrophysics Data System (ADS)

    Sujdak, E. J., Jr.

    1980-03-01

    This thesis is a study of radio frequency spectrum management as practiced by agencies and departments of the Federal Government. After a brief introduction to the international agency involved in radio frequency spectrum management, the author concentrates on Federal agencies engaged in frequency management. These agencies include the National Telecommunications and Information Administration (NTIA), the Interdepartment Radio Advisory Committee (IRAC), and the Department of Defense (DoD). Based on an analysis of Department of Defense frequency assignment procedures, recommendations are given concerning decentralizing military frequency assignment by delegating broader authority to unified commanders. This proposal includes a recommendation to colocate the individual Service frequency management offices at the Washington level. This would result in reduced travel costs, lower manpower requirements, and a common tri-Service frequency management data base.

  5. Multitaper Spectrum Estimates

    NASA Astrophysics Data System (ADS)

    Fodor, I. K.; Stark, P. B.

    Multitapering is a statistical technique developed to improve on the notorious periodogram estimate of the power spectrum (Thomson, 1982; Percival, Walden 1993). We show how to obtain orthogonal tapers for time series observed with gaps, and how to use statistical resampling techniques (Efron, Tibshirani 1993) to calculate realistic uncertainty estimates for multitaper estimates. We introduce multisegment multitapering. Multitapering can also be extended to the 2D case. We indicate how to construct tapers that minimize the spatial leakage in estimates of the spherical harmonic decomposition of the velocity images. Spatial multitapering followed by the temporal tapering of the estimated spherical harmonic time series is expected to result in improved spectrum and subsequent solar oscillation mode parameter estimates.

  6. The marine diversity spectrum.

    PubMed

    Reuman, Daniel C; Gislason, Henrik; Barnes, Carolyn; Mélin, Frédéric; Jennings, Simon

    2014-07-01

    Distributions of species body sizes within a taxonomic group, for example, mammals, are widely studied and important because they help illuminate the evolutionary processes that produced these distributions. Distributions of the sizes of species within an assemblage delineated by geography instead of taxonomy (all the species in a region regardless of clade) are much less studied but are equally important and will illuminate a different set of ecological and evolutionary processes. We develop and test a mechanistic model of how diversity varies with body mass in marine ecosystems. The model predicts the form of the 'diversity spectrum', which quantifies the distribution of species' asymptotic body masses, is a species analogue of the classic size spectrum of individuals, and which we have found to be a new and widely applicable description of diversity patterns. The marine diversity spectrum is predicted to be approximately linear across an asymptotic mass range spanning seven orders of magnitude. Slope -0.5 is predicted for the global marine diversity spectrum for all combined pelagic zones of continental shelf seas, and slopes for large regions are predicted to lie between -0.5 and -0.1. Slopes of -0.5 and -0.1 represent markedly different communities: a slope of -0.5 depicts a 10-fold reduction in diversity for every 100-fold increase in asymptotic mass; a slope of -0.1 depicts a 1.6-fold reduction. Steeper slopes are predicted for larger or colder regions, meaning fewer large species per small species for such regions. Predictions were largely validated by a global empirical analysis. Results explain for the first time a new and widespread phenomenon of biodiversity. Results have implications for estimating numbers of species of small asymptotic mass, where taxonomic inventories are far from complete. Results show that the relationship between diversity and body mass can be explained from the dependence of predation behaviour, dispersal, and life history on

  7. Evaluation of a spectral line width for the Phillips spectrum by means of numerical simulation

    NASA Astrophysics Data System (ADS)

    Korotkevich, A. O.; Zakharov, V. E.

    2015-05-01

    The work aims to check one of the assumptions under which the kinetic equation for water waves was derived in order to understand whether it can be applied to the situations described by the Phillips spectrum. We evaluate a spectral line width of the spectrum from the simulations in the framework of primordial dynamical equations at different levels of nonlinearity in the system, corresponding to the weakly turbulent Kolmogorov-Zakharov spectra ω-4, Phillips spectra ω-5, and intermediate cases. The original motivation of the work was to check one of the assumptions under which the kinetic equation for water waves was derived in order to understand whether it can be applied to the Phillips spectrum. It is shown that, even in the case of relatively high average steepness, when the Phillips spectrum is present in the system, the spectral lines are still very narrow, at least in the region of the direct cascade spectrum. It allows us to state that, even in the case of the Phillips spectrum, one of the assumptions used for the derivation of the Hasselmann kinetic equation is still valid, at least in the case of moderate whitecapping.

  8. Environmental effects on molecular and phenotypic variation in populations of Eruca sativa across a steep climatic gradient.

    PubMed

    Westberg, Erik; Ohali, Shachar; Shevelevich, Anatoly; Fine, Pinchas; Barazani, Oz

    2013-08-01

    In Israel Eruca sativa has a geographically narrow distribution across a steep climatic gradient that ranges from mesic Mediterranean to hot desert environments. These conditions offer an opportunity to study the influence of the environment on intraspecific genetic variation. For this, we combined an analysis of neutral genetic markers with a phenotypic evaluation in common-garden experiments, and environmental characterization of populations that included climatic and edaphic parameters, as well as geographic distribution. A Bayesian clustering of individuals from nine representative populations based on amplified fragment length polymorphism (AFLP) divided the populations into a southern and a northern geographic cluster, with one admixed population at the geographic border between them. Linear mixed models, with cluster added as a grouping factor, revealed no clear effects of environment or geography on genetic distances, but this may be due to a strong association of geography and environment with genetic clusters. However, environmental factors accounted for part of the phenotypic variation observed in the common-garden experiments. In addition, candidate loci for selection were identified by association with environmental parameters and by two outlier methods. One locus, identified by all three methods, also showed an association with trichome density and herbivore damage, in net-house and field experiments, respectively. Accordingly, we propose that because trichomes are directly linked to defense against both herbivores and excess radiation, they could potentially be related to adaptive variation in these populations. These results demonstrate the value of combining environmental and phenotypic data with a detailed genetic survey when studying adaptation in plant populations. This article describes the use of several types of data to estimate the influence of the environment on intraspecific genetic variation in populations originating from a steep

  9. Environmental effects on molecular and phenotypic variation in populations of Eruca sativa across a steep climatic gradient

    PubMed Central

    Westberg, Erik; Ohali, Shachar; Shevelevich, Anatoly; Fine, Pinchas; Barazani, Oz

    2013-01-01

    Abstract In Israel Eruca sativa has a geographically narrow distribution across a steep climatic gradient that ranges from mesic Mediterranean to hot desert environments. These conditions offer an opportunity to study the influence of the environment on intraspecific genetic variation. For this, we combined an analysis of neutral genetic markers with a phenotypic evaluation in common-garden experiments, and environmental characterization of populations that included climatic and edaphic parameters, as well as geographic distribution. A Bayesian clustering of individuals from nine representative populations based on amplified fragment length polymorphism (AFLP) divided the populations into a southern and a northern geographic cluster, with one admixed population at the geographic border between them. Linear mixed models, with cluster added as a grouping factor, revealed no clear effects of environment or geography on genetic distances, but this may be due to a strong association of geography and environment with genetic clusters. However, environmental factors accounted for part of the phenotypic variation observed in the common-garden experiments. In addition, candidate loci for selection were identified by association with environmental parameters and by two outlier methods. One locus, identified by all three methods, also showed an association with trichome density and herbivore damage, in net-house and field experiments, respectively. Accordingly, we propose that because trichomes are directly linked to defense against both herbivores and excess radiation, they could potentially be related to adaptive variation in these populations. These results demonstrate the value of combining environmental and phenotypic data with a detailed genetic survey when studying adaptation in plant populations. This article describes the use of several types of data to estimate the influence of the environment on intraspecific genetic variation in populations originating from a

  10. Hybrid spread spectrum radio system

    DOEpatents

    Smith, Stephen F [London, TN; Dress, William B [Camas, WA

    2010-02-09

    Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.

  11. Joint Electromagnetic Spectrum Management Operations

    DTIC Science & Technology

    2012-03-20

    synchronizing, and deconflicting JEMSMO actions (p. IV-7) Doctrine Update for JP 6-01, Joint Electromagnetic Spectrum Management Operations...communications system directorate of a joint staff (J-6), to support joint planning, coordination, and control of the spectrum for assigned forces. Executive...in the respective Service or joint publications. Interference Resolution To ensure critical frequencies and spectrum-dependent systems are

  12. The influence of sandstone caprock material on bedrock channel steepness within a tectonically passive setting: Buffalo National River Basin, Arkansas, USA

    NASA Astrophysics Data System (ADS)

    Thaler, E. A.; Covington, M. D.

    2016-09-01

    Bedrock channel profile analysis typically assumes that channels evolve toward a condition of topographic steady state where channel morphology is adjusted to rock erodibility, uplift rates, and stream power. Here we use the integral method of channel profile analysis to quantify channel steepness within a large set of tributary channels that incise through layered rocks in the Buffalo National River Basin in northern Arkansas. Statistical analysis of these channels demonstrates that normalized channel steepness is not a function of local bedrock lithology but is influenced by coarse sediment supply. Specifically, normalized steepness is greatest in reaches of the basin where an interval of Pennsylvanian sandstone forms a caprock on the ridges. Block detachment of the sandstone causes large boulders to be stranded in the upper tributaries where stream power is too low to mobilize or effectively erode the boulders. Within these channels, normalized steepness is correlated with sandstone boulder size and percent boulder coverage rather than local lithology, despite strong contrasts in the mechanical strength of the lithologies incised. This analysis suggests that removal of caprock material is rate limiting within the landscape and may be responsible for the long-term persistence of topography within this tectonically passive setting.

  13. X-ray spectra of a complete sample of extragalactic core-dominated radio sources

    NASA Technical Reports Server (NTRS)

    Brunner, H.; Lamer, G.; Worrall, D. M.; Staubert, R.

    1994-01-01

    We present ROSAT soft X-ray spectra for the members of a complete sample of 13 core-dominated, flat radio spectrum sources. The sample comprises all radio sources from a flux-limited radio catalog (S(sub 5GHz) greater than 1 Jy; Kuehr et al. 1981) which are north of delta = 70 deg, at galactic latitudes b greater than 10 deg, and have a flat radio spectrum between 1.4 and 5 GHz (alpha(sub r) less than 0.5; f approximately nu(sup -alpha)). The sources have already undergone much study at radio and optical wavelengths and are classified in broad terms as quasars (8 sources) and BL Lac objects (5 sources). We find mean X-ray power-law energy indices of alpha(sub x) = 0.59 +/- 0.19 for the quasars and 1.36 +/- 0.27 for the BL Lac objects (68% confidence range for two parameters of interest as determined by a maximum likelihood method), supporting earlier Einstein Observatory results for heterogeneous samples of sources (Worrall & Wilkes 1990). A non-zero dispersion on alpha(sub x) is found for both the quasars and the BL Lac objects. When we incorporate published radio, mm, and optical measurements and compare the X-ray and broad-band spectral indices alpha(sub x), alpha(sub rx), alpha(sub mm,x), and alpha(sub ox), the most obvious difference between the quasar and BL Lac subsamples lies within the X-ray band. We have fitted the multi-wavelength data to inhomogeneous synchotron-self-Compton models and find that, for the BL Lac objects with steep X-ray spectra, synchotron emission can account for the radio to soft X-ray measurements, whereas the BL Lac objects with hard X-ray spectra and the quasars require significant Compton emission to model the spectral flattening indicated by alpha(sub x) less than alpha(sub ox).

  14. Steepness and Concavity Controls on the Expression of Reach-Scale Channel Morphology, Debris Flow Deposition, and the Spatial Distribution of Salmonids in the Pacific Northwest

    NASA Astrophysics Data System (ADS)

    May, C. L.; Dietrich, W. E.

    2004-12-01

    Steepness and concavity indexes derived from the power function relationship between drainage area and channel slope provide a first-order control on (1) the expression of reach-scale channel morphology, (2) runout potential of debris flows, and (3) the spatial distribution of anadromous fish in the Pacific Northwest. Channels steeper than about 10% are typically dominated by the effects of periodic debris flow scour and subsequent accumulation of coarse sediment. Downstream of this area, channels with slopes between 3 to 10% represent a transition from debris flow to fluvial process dominance. In this transitional region of the network, debris flow deposits often form fill deposits that are subsequently incised by fluvial re-working that leads to the formation of step-pool sequences. Such reaches have restricted salmonid access, generally being most favorable to steelhead and cutthroat trout. The stronger the concavity of a channel profile, the shorter the length of this transitional reach. In the Oregon Coast Range, steepness and concavity values are high and the spatial extent of transitional channels is greatly restricted (typically only occurring in reaches with draining areas between 0.5 and 1.5 km2). The abrupt change in slope from steep debris flow prone channels to low-gradient pool-riffle and bedrock channels promotes debris flow deposition and fan formation at tributary junctions. In these highly concave basins, a relatively large proportion of the fluvial channel network have gradients below 3% and are accessible to salmonids, resulting in a broad spatial distribution. This broad distribution allows for a spreading of risk that may enhance a population's ability to persist during severe disturbance. In contrast, many catchments in the Klamath Mountains of northern California have high steepness values but low concavity. In this region, the portion of the network occupied by transitional reaches is greatly expanded. Step-pool channels dominate the

  15. Corn steep liquor as a nutrition adjunct for the production of Aspergillus niger lipase and hydrolysis of oils thereof.

    PubMed

    Edwinoliver, N G; Thirunavukarasu, K; Purushothaman, S; Rose, C; Gowthaman, M K; Kamini, N R

    2009-11-25

    Corn steep liquor (CSL) has been used as a nutrition adjunct for the production of an extracellular lipase from Aspergillus niger, which has immense importance as an additive in laundry detergent formulations. A five-level four-factorial central composite design was chosen to determine the optimal medium components with four critical variables, namely, CSL, NH4H2PO4, Na2HPO4, and sesame oil, that were found to be influential for lipase production by the classical one-factor-at-a-time method. The model suggested that all of the factors chosen had a significant impact on lipase production, and the optimum values of the influential parameters were CSL, 2.0%, w/v; NH4H2PO4, 0.05%, w/v; Na2HPO4, 0.75%, w/v; and sesame oil, 2.0%, w/v, with an activity of 26.7 U/mL at 48 h and 30 degrees C, which was 2.16-fold higher than the initial activity (12 U/mL) obtained by the conventional one-factor-at-a-time method. Furthermore, the enzyme has good potential for the hydrolysis of vegetable oils and fish oils, and a hydrolytic ratio of 88.73% was obtained with palm oil at 48 h. The utilization of CSL and sesame oil for lipase production from A. niger makes the process green, because both are renewable substrates and economically viable at an industrial scale.

  16. Automatic monitoring system for high-steep slope in open-pit mine based on GPS and data analysis

    NASA Astrophysics Data System (ADS)

    Zhou, Chunmei; Li, Xianfu; Qin, Sunwei; Qiu, Dandan; Wu, Yanlin; Xiao, Yun; Zhou, Jian

    2008-12-01

    Recently, GPS has been more and more applicative in open pit mine slope safety monitoring. Daye Iron Mine open pit high-steep slope automatic monitoring system mainly consists of three modules, namely, GPS data processing module, monitoring and warning module, emergency plans module. According to the rock mass structural feature and the side slope stability evaluation, it is arranged altogether to seven GPS distortion monitoring points on the sharp of Fault F9 at Daye iron Mine, adopted the combination of monofrequent static GPS receiver and data-transmission radio to carry on the observation, the data processing mainly uses three transect interpolation method to solve the questions of discontinuity and Effectiveness in the data succession. According to the displacement monitoring data from 1990 to 1996 of Daye Iron Mine East Open Pit Shizi mountain Landslide A2, researching the displacement criterion, rate criterion, acceleration criterion, creep curve tangent angle criterion etc of landslide failure, the result shows that the landslide A2 is the lapse type crag nature landslide whose movement in three phases, namely creep stage, accelerated phase, destruction stage. It is different of the failure criterion in different stages and different position that is at the rear, central, front margin of the landslide. It has important guiding significance to put forward the comprehensive failure criterion of seven new-settled monitoring points combining the slope deformation destruction and macroscopic evidence.

  17. In-situ Observations of Swash-zone Flow Velocities and Sediment Transport on a Steep Beach

    NASA Astrophysics Data System (ADS)

    Chardon-Maldonado, P.; Puleo, J. A.; Figlus, J.

    2014-12-01

    A 45 m scaffolding frame containing an array of instruments was installed at South Bethany Beach, Delaware, to obtain in-situ measurements in the swash zone. Six cross-shore stations were established to simultaneously measure near-bed velocity profiles, sediment concentration and water level fluctuations on a steep beach. Measurements of swash-zone hydrodynamics and morphological change were collected from February 12 to 25, 2014, following a large Nor'easter storm with surf zone significant wave height exceeding 5 m. Swash-zone flow velocities (u,v,w) were measured at each cross-shore location using a Nortek Vectrino profiling velocimeter that measured a 30 mm velocity profile at 1 mm vertical increments at 100 Hz. These velocity profiles were used to quantify the vertical flow structure over the foreshore and estimate hydrodynamic parameters such as bed shear stress and turbulent kinetic energy dissipation. Sediment concentrations were measured using optical backscatter sensors (OBS) to obtain spatio-temporal measurements during both uprush and backwash phases of the swash cycle. Cross-shore sediment transport rates at each station were estimated by taking the product of cross-shore velocity and sediment concentration. Foreshore elevations were sampled every low tide using a Leica GPS system with RTK capability. Cross-shore sediment transport rates and gradients derived from the velocities and bed shear stress estimates will be related to the observed morphological change.

  18. Multiscale Structure of the Underwater Adhesive of Phragmatopoma Californica: a Nanostructured Latex with a Steep Microporosity Gradient

    PubMed Central

    Stevens, Mark J.; Steren, Rebekah E.; Hlady, Vladimir; Stewart, Russell J.

    2008-01-01

    Phragmatopoma Californica builds a tubular dwelling by gluing bits of sand and seashell together underwater with a proteinaceous adhesive. In the lab, the animals will build with 0.5 mm glass beads. Two spots of glue with a consistent volume of about 100 pL each are deposited on the glass beads before placement on the end of the tube. The animals wriggled the particles for 20-30 s before letting go, which suggested that the adhesive was sufficiently set within 30 s to support the glass beads. The structure of the adhesive joints was examined at the micro- and nanoscopic length scales using laser scanning confocal and atomic force microscopies. At the microscale, the adhesive was a cellular solid with cell diameters ranging from 0.5 to 6.0 μm, distributed to create a steep porosity gradient that ranged from near zero at the outside edges to about 50% at the center of the adhesive joint. At the nanoscale, the adhesive appeared to be an accretion of trillions of deformable nanospheres, reminiscent of a high-solids-content latex adhesive. The implications of the structure for the functionality of the adhesive is discussed. PMID:17394366

  19. Vertical structure of pore pressure under surface gravity waves on a steep, megatidal, mixed sand-gravel-cobble beach

    NASA Astrophysics Data System (ADS)

    Guest, Tristan B.; Hay, Alex E.

    2017-01-01

    The vertical structure of surface gravity wave-induced pore pressure is investigated within the intertidal zone of a natural, steeply sloping, megatidal, mixed sand-gravel-cobble beach. Results from a coherent vertical array of buried pore pressure sensors are presented in terms of signal phase lag and attenuation as functions of oscillatory forcing frequency and burial depth. Comparison of the observations with the predictions of a theoretical poro-elastic bed response model indicates that the large observed phase lags and attenuation are attributable to interstitial trapped air. In addition to the dependence on entrapped air volume, the pore pressure phase and attenuation are shown to be sensitive to the hydraulic conductivity of the sediment, to the changing mean water depth during the tidal cycle, and to the redistribution/rearrangement of beach face material by energetic wave action during storm events. The latter result indicates that the effects on pore pressure of sediment column disturbance during instrument burial can persist for days to weeks, depending upon wave forcing conditions. Taken together, these results raise serious questions as to the practicality of using pore pressure measurements to estimate the kinematic properties of surface gravity waves on steep, mixed sand-gravel beaches.

  20. Actual geomorphological processes on steep hillslope vineyards. A comparison of Ruwertal (Germany) with the Montes de Málaga (Spain).

    NASA Astrophysics Data System (ADS)

    Rodrigo Comino, Jesús; Damián Ruiz Sinoga, José; María Senciales González, José; Guerra Merchán, Antonio; Seeger, Manuel; Ries, Johannes B.

    2016-04-01

    Nowadays, steep hillslope viticulture areas are one of the most complex agricultural eco-geomorphological systems in Europe. Precisely, the vineyards of the Ruwer-Mosel valley (Germany) and Montes de Málaga-Axarquía (Spain) are one clear example. Both regions are characterized by frequent heavy rainfall events, concentrated in summer (Germany) and autumn-winter (Spain), and intensive and not conservative land use managements on the soil (application of vine training systems, herbicides, non ecological amendments, anthropic rills generated by wheel traffic, footsteps in Germany and built by hoes or shovels in Spain). The goals of this work were: i) to determine and to quantify the hydrological and erosive phenomena in two traditional hillslope vineyards in Waldrach (Ruwer-Mosel valley, Germany) and Almáchar (Montes de Málaga-Axarquía, Spain); ii) to compare the geomorphological and hydrological dynamics of these study areas during diverse seasons and under different management conditions (Mediterranean and Continental climatic contexts, application of machineries, traditional protection measures...). For this purpose, a combined methodology performed by Trier and Málaga Universities with soil analysis, sediment traps, rainfall simulations and Guelph permeameter were applied. The main results showed high soil erosion and similar variations in the runoff and infiltration rates. In both study areas, geomorphological and hydrological dynamics registered several spatiotemporal variations along the upper, middle and foot slope, and during different seasons (before and after the vintage, and between the dry and humid period).

  1. Effects of steep high-frequency hearing loss on speech recognition using temporal fine structure in low-frequency region.

    PubMed

    Li, Bei; Hou, Limin; Xu, Li; Wang, Hui; Yang, Guang; Yin, Shankai; Feng, Yanmei

    2015-08-01

    The present study examined the effects of steep high-frequency sensorineural hearing loss (SHF-SNHL) on speech recognition using acoustic temporal fine structure (TFS) in the low-frequency region where the absolute thresholds appeared to be normal. In total, 28 participants with SHF-SNHL were assigned to 3 groups according to the cut-off frequency (1, 2, and 4 kHz, respectively) of their pure-tone absolute thresholds. Fourteen age-matched normal-hearing (NH) individuals were enrolled as controls. For each Mandarin sentence, the acoustic TFS in 10 frequency bands (each 3-ERB wide) was extracted using the Hilbert transform and was further lowpass filtered at 1, 2, and 4 kHz. Speech recognition scores were compared among the NH and 1-, 2-, and 4-kHz SHF-SNHL groups using stimuli with varying bandwidths. Results showed that speech recognition with the same TFS-speech stimulus bandwidth differed significantly in groups and filtering conditions. Sentence recognition in quiet conditions was better than that in noise. Compared with the NH participants, nearly all the SHF-SNHL participants showed significantly poorer sentence recognition within their frequency regions with "normal hearing" (defined clinically by normal absolute thresholds) in both quiet and noisy conditions. These may result from disrupted auditory nerve function in the "normal hearing" low-frequency regions.

  2. Experimental evidence of negative quantum capacitance in topological insulator for sub-60-mV/decade steep switching device

    NASA Astrophysics Data System (ADS)

    Choi, H.; Lee, H.; Park, J.; Yu, H.-Y.; Kim, T. G.; Shin, C.

    2016-11-01

    As a three-dimensional topological insulator (TI), bismuth telluride (Bi2Te3) has two-dimensional electron gas on its surface where negative quantum capacitance (NQC) can exist at a specific biasing condition. In order to experimentally confirm NQC in a TI, a metal-insulator-semiconductor (MIS) capacitor (i.e., metal-Bi2Te3-SiO2-silicon) is fabricated. The capacitance-voltage measurement of the MIS capacitor at 300 K shows that as the depletion capacitance in silicon decreases, the total capacitance of the MIS capacitor, which consists of two capacitors connected in series (i.e., insulator capacitor and depletion capacitor), increases in the depletion region at a frequency of 50 kHz. The amplified capacitance indicates the existence of NQC on the surface of the TI, and it originates from the strongly correlated electron system. The NQC of the TI opens avenues for sub-60-mV/decade steep switching silicon devices.

  3. Connectivity and topographic thresholds in bi-hourly soil moisture measurements along transects on a steep hillslope

    NASA Astrophysics Data System (ADS)

    Kim, Sanghyun

    2014-05-01

    Observation of temporal variations in soil moisture along transects is important when examining hydrological processes on a hillslope. Although there is substantial interest in characterizing catchment hydrology through an investigation of hydrologic connectivity, few attempts have been made to explore hydrologic connectivity within soil layers using soil moisture observations. Mathematical relationships among soil moisture differences are reproducible when Granger causality is defined within the context of hydrological connectivity because the process based transfer functions facilitate soil moisture predictions. Soil moisture time series along two transects on a steep hillslope were obtained using a multiplexed time domain reflectometry system during the growing season in June 2008 and 2009. The transfer function relationships between multiple soil moisture differences were delineated to determine a representative point for reliable time series modeling, and to establish the spatial pattern of areal clusters that will enable model identification and prediction. The impact of hillslope topography on the modeling of coupled soil moisture was highlighted by configuring the threshold behavior of model predictability. Results showed that soil moisture temporal relationships can be used for the prediction of volumetric soil moisture, within a specific area associated with representation point. Reliable relationships among soil moistures were apparent for points having greater upslope areas between 400 m2 and 1000 m2.

  4. Avian orientation at steep angles of inclination: experiments with migratory white-crowned sparrows at the magnetic North Pole.

    PubMed

    Akesson, S; Morin, J; Muheim, R; Ottosson, U

    2001-09-22

    The Earth's magnetic field and celestial cues provide animals with compass information during migration. Inherited magnetic compass courses are selected based on the angle of inclination, making it difficult to orient in the near vertical fields found at high geomagnetic latitudes. Orientation cage experiments were performed at different sites in high Arctic Canada with adult and young white-crowned sparrows (Zonotrichia leucophrys gambelii) in order to investigate birds' ability to use the Earth's magnetic field and celestial cues for orientation in naturally very steep magnetic fields at and close to the magnetic North Pole. Experiments were performed during the natural period of migration at night in the local geomagnetic field under natural clear skies and under simulated total overcast conditions. The experimental birds failed to select a meaningful magnetic compass course under overcast conditions at the magnetic North Pole, but could do so in geomagnetic fields deviating less than 3 degrees from the vertical. Migratory orientation was successful at all sites when celestial cues were available.

  5. From steep feeders to tabular plutons - Emplacement controls of syntectonic granitoid plutons in the Damara Belt, Namibia

    NASA Astrophysics Data System (ADS)

    Hall, Duncan; Kisters, Alexander

    2016-01-01

    Granitoid plutons in the deeply eroded south Central Zone of the Damara Belt in Namibia commonly show tabular geometries and pronounced stratigraphic controls on their emplacement. Subhorizontal, sheet-like pluton geometries record emplacement during regional subhorizontal shortening, but the intrusion of spatially and temporally closely-related granitoid plutons at different structural levels and in distinct structural settings suggests independent controls on their levels of emplacement. We describe and evaluate the controls on the loci of the dyke-to-sill transition that initiated the emplacement of three syntectonic (560-530 Ma) plutons in the basement-cover stratigraphy of the Erongo region. Intrusive relationships highlight the significance of (1) rigidity anisotropies associated with competent sedimentary packages or pre-existing subhorizontal granite sheets and (2) rheological anisotropies associated with the presence of thick ductile marble horizons. These mechanical anisotropies may lead to the initial deflection of steep feeder conduits as well as subsequent pluton assembly by the repeated underaccretion of later magma batches. The upward displacement of regional isotherms due to the heat advection associated with granite emplacement is likely to have a profound effect on the mechanical stratification of the upper crust and, consequently, on the level at which granitoid pluton emplacement is initiated. In this way, pluton emplacement at progressively shallower crustal depths may have resulted in the unusually high apparent geothermal gradients recorded in the upper crustal levels of the Damara Belt during its later evolution.

  6. Effects of Systemic Administration of Dexmedetomidine on Intraocular Pressure and Ocular Perfusion Pressure during Laparoscopic Surgery in a Steep Trendelenburg Position: Prospective, Randomized, Double-Blinded Study

    PubMed Central

    2016-01-01

    Increased intraocular pressure (IOP) during surgery is a risk factor for postoperative ophthalmological complications. We assessed the efficacy of systemically infused dexmedetomidine in preventing the increase in IOP caused by a steep Trendelenburg position, and evaluated the influence of underlying hypertension on IOP during surgery. Sixty patients undergoing laparoscopic surgery in a steep Trendelenburg position were included. Patients in the dexmedetomidine group received a 1.0 µg/kg IV loading dose of dexmedetomidine before anesthesia, followed by an infusion of 0.5 µg/kg/hr throughout the operation. Patients in the saline group were infused with the same volume of normal saline. IOP and ocular perfusion pressure (OPP) were measured 16 times pre- and intraoperatively. In the saline group, IOP increased in the steep Trendelenburg position, and was 11.3 mmHg higher at the end of the time at the position compared with the baseline value (before anesthetic induction). This increase in IOP was attenuated in the dexmedetomidine group, for which IOP was only 4.2 mmHg higher (P < 0.001 vs. the saline group). The steep Trendelenburg position was associated with a decrease in OPP; the degree of decrease was comparable for both groups. In intragroup comparisons between patients with underlying hypertension and normotensive patients, the values of IOP at every time point were comparable. Dexmedetomidine infusion attenuated the increase in IOP during laparoscopic surgery in a steep Trendelenburg position, without further decreasing the OPP. Systemic hypertension did not seem to be associated with any additional increase in IOP during surgery. (Registration at the Clinical Research Information Service of Korea National Institute of Health ID: KCT0001482) PMID:27247511

  7. Spectrum of Fascicular Arrhythmias.

    PubMed

    Sung, Raphael; Scheinman, Melvin

    2016-09-01

    Fascicular arrhythmias encompass a wide spectrum of ventricular arrhythmias that depend on the specialized conduction system of the right and left ventricles. These arrhythmias include premature ventricular complexes, monomorphic ventricular tachycardia, polymorphic ventricular tachycardia, and ventricular fibrillation. These arrhythmias may be organized by mechanism, including intrafascicular reentry, interfascicular reentry, and focal. Mapping and ablation of the fascicular system can result in high cure rates of debilitating and potentially life-threatening arrhythmias. When approaching these arrhythmias, careful consideration of the structure of the His Purkinje system as well as their electrophysiologic properties may help guide even the most complex of arrhythmias.

  8. Flow Around Steep Topography

    DTIC Science & Technology

    2015-09-30

    appreciable energy/ momentum is lost from the large-scale NEC flow to smaller scales and through which processes? • What limits numerical models/state...to address two overarching hypotheses: • Energy and momentum are lost in appreciable amounts due to encounters between low-frequency flows and

  9. A Steep Climb

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows a screenshot from software used by engineers to drive the Mars Exploration Rover Spirit up toward the rim of the crater dubbed 'Bonneville.' The software simulates the rover's movements across the martian terrain, helping to plot a safe course. The virtual 3-D world around the rover is built from images taken by Spirit's stereo navigation cameras. Regions for which the rover has not yet acquired 3-D data are represented in beige. The red darts show target destinations. Red lines indicate the path the rover's wheels will follow to reach the target, and the blue line denotes the path of the rover's 'belly button,' as engineers like to call it.

    In this picture, Spirit is parked at its present location 16 meters (52 feet) away from the crater's rim. Later today, it will drive the rest of the way to 'Bonneville'.

  10. FFT-Based Spectrum Analysis Using a Digital Signal Processor

    DTIC Science & Technology

    2007-11-02

    thus far incomplete) Search for ExtraTerrestrial Intelligence (SETI) all rely on detecting the presence of radio signals of unknown frequency, power...instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send...Spectrum analysis is the context of this thesis. Spectrum conflict management, sig- nals intelligence , technical security, space probe telemetry, and the

  11. A method for generating a synthetic spectrum within Zemax

    NASA Astrophysics Data System (ADS)

    Gibson, Steven R.; Wishnow, Edward H.

    2016-08-01

    A method using non-sequential Zemax to produce a pixelated synthetic spectrum is described. This simulation was developed for the Keck Planet Finder (KPF) instrument, and will prove useful for engineering performance analyses (stability, stray light, order cross-talk, distortion, etc.). It has also provided a set of synthetic spectra to be used during the development of the data pipeline. Various aspects concerning the construction of the spectrum are described, including: converting a model from sequential to non-sequential Zemax, the creation of Zemax coating files for echelle blaze functions, and the generation of spectrum source files (solar, thorium-argon, incandescent, Fabry-Perot etalon and laser frequency comb).

  12. Optical system design of dual-spectrum autocollimator

    NASA Astrophysics Data System (ADS)

    Wei, Yongjing; Wu, Yiming; Xiao, Maosen; Lu, Weiguo

    2015-10-01

    The optical system design of a new dual-spectrum autocollimator which can measure two different spatial azimuths simultaneously is proposed. According to the principle of dual-spectrum autocollimator, ZEMAX software is used to design and optimize the optical system. Since two light sources with different wavelength are used in the autocollimator, chromatic aberration is required to reduce off in the optical system design. The experimental results demonstrate that the measuring range of the dual-spectrum autocollimator is up to +/-30', the deviation is less than 1″, and the resolution can reach 0.1". The designed autocollimator can simultaneously measure two different azimuths fastly and accurately.

  13. The marine diversity spectrum

    PubMed Central

    Reuman, Daniel C; Gislason, Henrik; Barnes, Carolyn; Mélin, Frédéric; Jennings, Simon

    2014-01-01

    Distributions of species body sizes within a taxonomic group, for example, mammals, are widely studied and important because they help illuminate the evolutionary processes that produced these distributions. Distributions of the sizes of species within an assemblage delineated by geography instead of taxonomy (all the species in a region regardless of clade) are much less studied but are equally important and will illuminate a different set of ecological and evolutionary processes. We develop and test a mechanistic model of how diversity varies with body mass in marine ecosystems. The model predicts the form of the ‘diversity spectrum’, which quantifies the distribution of species' asymptotic body masses, is a species analogue of the classic size spectrum of individuals, and which we have found to be a new and widely applicable description of diversity patterns. The marine diversity spectrum is predicted to be approximately linear across an asymptotic mass range spanning seven orders of magnitude. Slope −0·5 is predicted for the global marine diversity spectrum for all combined pelagic zones of continental shelf seas, and slopes for large regions are predicted to lie between −0·5 and −0·1. Slopes of −0·5 and −0·1 represent markedly different communities: a slope of −0·5 depicts a 10-fold reduction in diversity for every 100-fold increase in asymptotic mass; a slope of −0·1 depicts a 1·6-fold reduction. Steeper slopes are predicted for larger or colder regions, meaning fewer large species per small species for such regions. Predictions were largely validated by a global empirical analysis. Results explain for the first time a new and widespread phenomenon of biodiversity. Results have implications for estimating numbers of species of small asymptotic mass, where taxonomic inventories are far from complete. Results show that the relationship between diversity and body mass can be explained from the dependence of predation behaviour

  14. Characterizing a Neutron Energy Spectrum Using a "Forward Edge" Neutron Time-of-Flight Spectroscopy Technique

    DTIC Science & Technology

    2005-03-01

    energy spectrum of monoenergetic neutron source [9:562]..............................................27 16. Example data set...is valid only when the absorber is composed of one material and the incident neutrons are monoenergetic . In the case where the absorber consists of...source due to its creation from monoenergetic neutrons . Figure 15: Proton recoil energy spectrum of monoenergetic neutron source [9:562

  15. Supply and dispersal of flood sediment from a steep, tropical watershed: Hanalei Bay, Kaua'i, Hawai'i, USA

    USGS Publications Warehouse

    Draut, A.E.; Bothner, Michael H.; Field, M.E.; Reynolds, R.L.; Cochran, S.A.; Logan, J.B.; Storlazzi, C.D.; Berg, C.J.

    2009-01-01

    In contrast to many small, mountainous watersheds in temperate coastal regions, where fluvial discharge and wave energy commonly coincide, deposition and reworking of tropical flood sediment can be seasonally decoupled, and this has important implications for coral-reef ecosystems. An understanding of the interaction between tropical flood sedimentation and wave climate is essential to identifying and mitigating effects of watershed changes on coral reefs as urbanization and climate change proceed. Sedimentary facies and isotopic properties of sediment in Hanalei Bay, on the island of Kaua'i, Hawai'i, USA, were used to assess deposition and reworking of flood deposits from the Hanalei River in a case study demonstrating the potential ecosystem effects of runoff from a steep, tropical watershed. In Hanalei Bay, the youngest and thickest terrigenous sediment was consistently present near the river mouth and in a bathymetric depression that acted as at least a temporary sediment sink. During this 2 yr study, the largest flood events occurred in late winter and spring 2006; substantial terrestrial sediment delivered by those floods still remained in the bay as of June 2006 because oceanic conditions were not sufficiently energetic to transport all of the sediment offshore. Additional sediment was deposited in the bay by a summer 2006 flood that coincided with seasonal low wave energy. In most years, flood sediment accumulating in the bay and on its fringing reefs would be remobilized and advected out of the bay during winter, when the wave climate is energetic. Turbidity and sedimentation on corals resulting from late spring and summer floods during low wave energy could have a greater impact on coral-reef ecosystems than floods in other seasons, an effect that could be exacerbated if the incidence and sediment load of tropical summer floods increase due to urbanization and climate change. ?? 2008 Geological Society of America.

  16. Confirmation of a Steep Luminosity Function for Ly alpha Emitters at z 5.7: a Major Component of Reionization

    NASA Technical Reports Server (NTRS)

    Dressler, Alan; Henry, Alaina L.; Martin, Crystal L.; Sawicki, Marcin; McCarthy, Patrick; Villaneuva, Edward

    2014-01-01

    We report the first direct and robust measurement of the faint-end slope of the Ly-alpha emitter (LAE) luminosity function at z = 5.7. Candidate LAEs from a low-spectral-resolution blind search with IMACS on Magellan- Baade were targeted at higher resolution to distinguish high redshift LAEs from foreground galaxies. All but 2 of our 42 single-emission-line systems are fainter than F = 2.0×10(exp-17) ergs s(exp-1) cm(exp-2), making these the faintest emission-lines observed for a z = 5.7 sample with known completeness, an essential property for determining the faint end slope of the LAE luminosity function. We find 13 LAEs as compared to 29 foreground galaxies, in very good agreement with the modeled foreground counts predicted in Dressler et al. (2011a) that had been used to estimate a faint-end slope of alpha = -2.0 for the LAE luminosity function. A 32% LAE fraction, LAE/(LAE+foreground) within the flux interval F = 2-20 × 10(exp-18) ergs s(exp-1) cm(exp-2) constrains the faint end slope of the luminosity function to -1.95 greater than alpha greater than -2.35 (1 delta). We show how this steep LF should provide, to the limit of our observations, more than 20% of the flux necessary to maintain ionization at z = 5.7, with a factor-of-ten extrapolation in flux reaching more than 55%. We suggest that this bodes well for a comparable contribution by similar, low-mass star forming galaxies at higher-redshift - within the reionization epoch at z greater than approximately 7, only 250 Myr earlier - and that such systems provide a substantial, if not dominant, contribution to the late-stage reionization of the IGM.

  17. Sub-nanosecond time resolved light emission study for diffuse discharges in air under steep high voltage pulses

    NASA Astrophysics Data System (ADS)

    Tardiveau, P.; Magne, L.; Marode, E.; Ouaras, K.; Jeanney, P.; Bournonville, B.

    2016-10-01

    Pin-to-plane discharges in centimetre air gaps and standard conditions of pressure and temperature are generated under very high positive nanosecond scale voltage pulses. The experimental study is based on recordings of sub-nanosecond time resolved and Abel-processed light emission profiles and their complete correlation to electrical current waveforms. The effects of the voltage pulse features (amplitude between 20 and 90 kV, rise time between 2 and 5.2 ns, and time rate between 4 and 40 kV · ns-1) and the electrode configuration (gap distance between 10 and 30 mm, pin radius between 10 and 200 µm, copper, molybdenum or tungsten pin material) are described. A three time period development can be found: a glow-like structure with monotonic light profiles during the first 1.5 ns whose size depends on time voltage rate, a shell-like structure with bimodal profiles whose duration and extension in space depends on rise time, and either diffuse or multi-channel regime for the connection to the cathode plane according to gap distance. The transition of the light from monotonic to bimodal patterns reveals the relative effects and dynamics of streamer space charge and external laplacian field. A classical 2D-fluid model for streamer propagation has been used and adapted for very high and steep voltage pulses. It shows the formation of a strong space charge (streamer) very close to the pin, but also a continuity of emission between the pin and the streamer, and electric fields higher than the critical ionization field (28 kV · cm-1 in air) almost in the whole gap and very early in the discharge propagation.

  18. Hydraulics of outburst floods spilling over a steep-walled canyon: Implications for paleo-discharges on Mars

    NASA Astrophysics Data System (ADS)

    Lapotre, Mathieu; Lamb, Michael

    2013-04-01

    Canyons carved by outburst floods are common landforms on Earth and Mars. These canyons are generally found in fractured basalts and jointed sedimentary rocks. Flood-carved canyons commonly have steep headwalls and a roughly constant width, and are often thought to have formed from upstream headwall propagation due to waterfall erosion. Because morphology is readily available from satellite imagery, these canyons offer a unique opportunity to quantify the discharge of rare, catastrophic paleo-floods on Earth and Mars. However, mechanistic relationships that relate canyon size to flood discharge have yet to be developed. We propose that the width of a canyon headwall in fractured rock is set by the spatial distribution of erosion around the rim of the canyon, which is controlled by the distribution of shear stresses induced by the overflowing water as it is focused into the canyon head. We test this hypothesis by performing a series of numerical simulations of flood-water focusing using ANUGA Hydro, a 2D-depth averaged, fully turbulent, hydraulic numerical modeling suite allowing for Froude-number transitions. The numerical simulations were designed to explore five dimensionless variables: the aspect ratio of the canyon (length normalized by width), the canyon width to flood-water width ratio, the canyon width to normal-flow depth ratio, the Froude number, and the topographic gradient upstream of the canyon. Preliminary results show that flow focusing leads to increased shear stresses at the canyon head compared to the sides of the canyon for subcritical floods and higher canyon aspect ratios. This suggests that proto-canyons start growing from a topographic defect in all directions until they reach a critical length for the side walls to dry. Once this critical length is attained, canyons focus most of the flood waters into their heads, and propagate upstream only, maintaining roughly constant widths. Preliminary results suggest that canyon width may be used to

  19. Morphometric and meteorological controls of snow avalanche distribution and activity at hillslopes in steep mountain valleys in western Norway

    NASA Astrophysics Data System (ADS)

    Laute, Katja; Beylich, Achim A.

    2013-04-01

    Snow avalanches are common phenomena in Norway due to the interactions between the prevalent climatic factors and local topography. Research on snow avalanches provides insights into possible effects of predicted climate change on avalanche activity and connected sediment transport in mountain areas. This study focuses on (i) controlling factors of avalanche distribution and activity, and (ii) their relative importance regarding mass transfers in two steep, parabolic-shaped and glacier-connected tributary valleys (Erdalen and Bødalen) in western Norway. Mapping of distribution, extension and run-out distances of avalanches is combined with spatial data analysis of morphometric controls. Based on correlation of climate data with monitored avalanche events the timing and frequency of avalanches is explored and debris mass transfer on hillslopes caused by avalanches is estimated. The denudative effect of snow avalanches occurs in two steps: firstly throughout erosion directly on the surface of the rockwall and secondly due to their transport ability which causes significant remobilization and transport of available debris further downslope. The spatial distribution of snow avalanches depends on the valley orientation, slope aspect and rockwall morphometry. Especially distinct laterally convex-shaped leeside upper rockwall areas allow a high accumulation rate of snow during winter which is then released as avalanches during spring. The timing and frequency of avalanches in both valleys depend mainly on snowfall intensity, periods with strong winds combined with a stable wind direction or sudden air temperature changes. Snow avalanche activity leads in some valley areas to significant hillslope-channel coupling because debris is transported far enough by avalanches to reach channels. Snow avalanches represent one of the dominant denudational processes and have a high relative importance regarding mass transfer within the sedimentary budgets of the entire valleys.

  20. Low Dopamine D2/D3 Receptor Availability is Associated with Steep Discounting of Delayed Rewards in Methamphetamine Dependence

    PubMed Central

    Ballard, Michael E.; Mandelkern, Mark A.; Monterosso, John R.; Hsu, Eustace; Robertson, Chelsea L.; Ishibashi, Kenji; Dean, Andy C.

    2015-01-01

    Background: Individuals with substance use disorders typically exhibit a predilection toward instant gratification with apparent disregard for the future consequences of their actions. Indirect evidence suggests that low dopamine D2-type receptor availability in the striatum contributes to the propensity of these individuals to sacrifice long-term goals for short-term gain; however, this possibility has not been tested directly. We investigated whether striatal D2/D3 receptor availability is negatively correlated with the preference for smaller, more immediate rewards over larger, delayed alternatives among research participants who met DSM-IV criteria for methamphetamine (MA) dependence. Methods: Fifty-four adults (n = 27 each: MA-dependent, non-user controls) completed the Kirby Monetary Choice Questionnaire, and underwent positron emission tomography scanning with [18F]fallypride. Results: MA users displayed steeper temporal discounting (p = 0.030) and lower striatal D2/D3 receptor availability (p < 0.0005) than controls. Discount rate was negatively correlated with striatal D2/D3 receptor availability, with the relationship reaching statistical significance in the combined sample (r = -0.291, p = 0.016) and among MA users alone (r = -0.342, p = 0.041), but not among controls alone (r = -0.179, p = 0.185); the slopes did not differ significantly between MA users and controls (p = 0.5). Conclusions: These results provide the first direct evidence of a link between deficient D2/D3 receptor availability and steep temporal discounting. This finding fits with reports that low striatal D2/D3 receptor availability is associated with a higher risk of relapse among stimulant users, and may help to explain why some individuals choose to continue using drugs despite knowledge of their eventual negative consequences. Future research directions and therapeutic implications are discussed. PMID:25603861