Science.gov

Sample records for gas poor transition

  1. Gas turbine combustor transition

    DOEpatents

    Coslow, B.J.; Whidden, G.L.

    1999-05-25

    A method is described for converting a steam cooled transition to an air cooled transition in a gas turbine having a compressor in fluid communication with a combustor, a turbine section in fluid communication with the combustor, the transition disposed in a combustor shell and having a cooling circuit connecting a steam outlet and a steam inlet and wherein hot gas flows from the combustor through the transition and to the turbine section, includes forming an air outlet in the transition in fluid communication with the cooling circuit and providing for an air inlet in the transition in fluid communication with the cooling circuit. 7 figs.

  2. Gas turbine combustor transition

    DOEpatents

    Coslow, Billy Joe; Whidden, Graydon Lane

    1999-01-01

    A method of converting a steam cooled transition to an air cooled transition in a gas turbine having a compressor in fluid communication with a combustor, a turbine section in fluid communication with the combustor, the transition disposed in a combustor shell and having a cooling circuit connecting a steam outlet and a steam inlet and wherein hot gas flows from the combustor through the transition and to the turbine section, includes forming an air outlet in the transition in fluid communication with the cooling circuit and providing for an air inlet in the transition in fluid communication with the cooling circuit.

  3. Biographies of Exclusion: Poor Work and Poor Transitions

    ERIC Educational Resources Information Center

    Shildrick, Tracy; MacDonald, Robert

    2007-01-01

    The usefulness of the concept of transition has been hotly contested in Anglophone youth studies over the past decade. A variety of criticisms have been ranged against it, including that it: presumes the continuing predominance of linear, obvious, mainstream pathways to adulthood; excludes wider youth questions in focusing narrowly on educational…

  4. Circumgalactic gas absorption in extremely metal-poor dwarf dalaxies

    NASA Astrophysics Data System (ADS)

    Filho, M. E.; Sánchez Almeida, J.; Muñoz Tuñón, C.

    2017-03-01

    Accretion of metal-poor gas via cold accretion flows has been recently proposed as a means to trigger/sustain star formation in extremely metal-poor dwarf galaxies (XMPs), a scenario in agreement with theoretical predictions. We report on the tentative detection of CaII absorption used to trace the conditions of the gas clouds in the halo of the XMP UGCA 20.

  5. Marriage or dissolution? Union transitions among poor cohabiting women.

    PubMed

    Lichter, Daniel T; Qian, Zhenchao; Mellott, Leanna M

    2006-05-01

    The objective of this paper is to identify the incentives and barriers to marriage among cohabiting women, especially disadvantaged mothers who are targets of welfare reform. We use the newly released cohabitation data from the National Longitudinal Survey of Youth (1979-2000), which tracks the partners of cohabiting women across survey waves. Our results support several conclusions. First, cohabiting unions are short-lived--about one-half end within one year, and over 90% end by the fifth year. Unlike most previous research, our results show that most cohabiting unions end by dissolution of the relationship rather than by marriage. Second, transitions to marriage are especially unlikely among poor women; less than one-third marry within five years. Cohabitation among poor women is more likely than that among nonpoor women to be a long-term alternative or substitute for traditional marriage. Third, our multinomial analysis of transitions from cohabitation into marriage or dissolution highlights the salience of economically disadvantaged family backgrounds, cohabitation and fertility histories, women's economic resources, and partner characteristics. These results are interpreted in a policy environment that increasingly views marriage as an economic panacea for low-income women and their children.

  6. Bacteriorhodopsin folds through a poorly organized transition state.

    PubMed

    Schlebach, Jonathan P; Woodall, Nicholas B; Bowie, James U; Park, Chiwook

    2014-11-26

    The folding mechanisms of helical membrane proteins remain largely uncharted. Here we characterize the kinetics of bacteriorhodopsin folding and employ φ-value analysis to explore the folding transition state. First, we developed and confirmed a kinetic model that allowed us to assess the rate of folding from SDS-denatured bacteriorhodopsin (bRU) and provides accurate thermodynamic information even under influence of retinal hydrolysis. Next, we obtained reliable φ-values for 16 mutants of bacteriorhodopsin with good coverage across the protein. Every φ-value was less than 0.4, indicating the transition state is not uniquely structured. We suggest that the transition state is a loosely organized ensemble of conformations.

  7. Yield stress transition in gas fluidized sand.

    NASA Astrophysics Data System (ADS)

    Stoker, David; Poker, Jennifer; Savrin, Tamara; Rutgers, Maarten

    2000-11-01

    Gas fluidized powders can take on three distinct states. I: Solid like for low gas flow rates. II: At intermediate flow rates, the bed expands and drastically reduces its yield stress, i.e. quicksand which cannot support the weight of solid objects. III: At high flow rates rising gas bubbles churn the sand grains violently. We have measured that the transition from regime I to II does not occur simultaneously for the entire column, but rather as a well defined front which sweeps through the column as a function of gas flow rate. Earlier measurements sensed this front by measuring the depth to which a brass sphere would sink in the liquid phase. We have supplemented this with careful measurements of the vertical gas pressure gradient throughout the column. The pressure profile shows a distinct change in the gradient at a height which correlates well with results from the sinking sphere measurement. From the pressure gradient we calculate the local gas permeability of the sand, which is related to the grain density, which can be measured with an accuracy of better than 1 part in 100. We thank the NSF-REU program for partial support of this research.

  8. HD 100453: A Link Between Gas-Rich Protoplanetary Disks and Gas-Poor Debris Disks

    NASA Astrophysics Data System (ADS)

    Collins, K. A.; Grady, C. A.; Hamaguchi, K.; Wisniewski, J. P.; Brittain, S.; Sitko, M.; Carpenter, W. J.; Williams, J. P.; Mathews, G. S.; Williger, G. M.; van Boekel, R.; Carmona, A.; Henning, Th.; van den Ancker, M. E.; Meeus, G.; Chen, X. P.; Petre, R.; Woodgate, B. E.

    2009-05-01

    HD 100453 has an IR spectral energy distribution (SED) which can be fit with a power law plus a blackbody. Previous analysis of the SED suggests that the system is a young Herbig Ae star with a gas-rich, flared disk. We reexamine the evolutionary state of the HD 100453 system by refining its age (based on a candidate low-mass companion) and by examining limits on the disk extent, mass accretion rate, and gas content of the disk environment. We confirm that HD 100453B is a common proper motion companion to HD 100453A, with a spectral type of M4.0V-M4.5V, and derive an age of 10 ± 2 Myr. We find no evidence of mass accretion onto the star. Chandra ACIS-S imagery shows that the Herbig Ae star has L x/L bol and an X-ray spectrum similar to nonaccreting β Pic Moving Group early F stars. Moreover, the disk lacks the conspicuous Fe II emission and excess FUV continuum seen in spectra of actively accreting Herbig Ae stars, and from the FUV continuum, we find the accretion rate is < 1.4 × 10-9 M sun yr-1. A sensitive upper limit to the CO J = 3-2 intensity indicates that the gas in the outer disk is likely optically thin. Assuming a [CO]/[H2] abundance of 1 × 10-4 and a depletion factor of 103, we find that the mass of cold molecular gas is less than ~0.33 M J and that the gas-to-dust ratio is no more than ~4:1 in the outer disk. The combination of a high fractional IR excess luminosity, a relatively old age, an absence of accretion signatures, and an absence of detectable circumstellar molecular gas suggests that the HD 100453 system is in an unusual state of evolution between a gas-rich protoplanetary disk and a gas-poor debris disk.

  9. Dust-to-gas Ratio in the Extremely Metal-poor Galaxy I Zw 18

    NASA Astrophysics Data System (ADS)

    Herrera-Camus, Rodrigo; Fisher, David B.; Bolatto, Alberto D.; Leroy, Adam K.; Walter, Fabian; Gordon, Karl. D.; Roman-Duval, Julia; Donaldson, Jessica; Meléndez, Marcio; Cannon, John M.

    2012-06-01

    The blue compact dwarf galaxy I Zw 18 is one of the most metal-poor systems known in the local universe (12+log(O/H) = 7.17). In this work we study I Zw 18 using data from Spitzer, Herschel Space Telescope, and IRAM Plateau de Bure Interferometer. Our data set includes the most sensitive maps of I Zw 18, to date, in both the far-infrared and the CO J = 1 → 0 transition. We use dust emission models to derive a dust mass upper limit of only M dust <= 1.1 × 104 M ⊙ (3σ limit). This upper limit is driven by the non-detection at 160 μm, and it is a factor of 4-10 times smaller than previous estimates (depending on the model used). We also estimate an upper limit to the total dust-to-gas mass ratio of M Dust/M gas <= 5.0 × 10-5. If a linear correlation between the dust-to-gas mass ratio and metallicity (measured as O/H) were to hold, we would expect a ratio of 3.9 × 10-4. We also show that the infrared spectral energy distribution is similar to that of starbursting systems.

  10. Transitional Gas Jet Diffusion Flames in Microgravity

    NASA Technical Reports Server (NTRS)

    Agrawal, Ajay K.; Alammar, Khalid; Gollahalli, S. R.; Griffin, DeVon (Technical Monitor)

    2000-01-01

    Drop tower experiments were performed to identify buoyancy effects in transitional hydrogen gas jet diffusion flames. Quantitative rainbow schlieren deflectometry was utilized to optically visualize the flame and to measure oxygen concentration in the laminar portion of the flame. Test conditions consisted of atmospheric pressure flames burning in quiescent air. Fuel from a 0.3mm inside diameter tube injector was issued at jet exit Reynolds numbers (Re) of 1300 to 1700. Helium mole percentage in the fuel was varied from 0 to 40%. Significant effects of buoyancy were observed in near field of the flame even-though the fuel jets were momentum-dominated. Results show an increase of breakpoint length in microgravity. Data suggest that transitional flames in earth-gravity at Re<1300 might become laminar in microgravity.

  11. Gas permeation through nanoporous membranes in the transitional flow region

    NASA Astrophysics Data System (ADS)

    Petukhov, D. I.; Eliseev, A. A.

    2016-02-01

    An experimental study on the permeability of anodic alumina (20-120 nm) and track-etched (30 nm) nanoporous membranes for different gases in the transitional flow regime is reported in the range of Knudsen numbers from 0.1 to 10. A significant variation (up to 30%) of the membrane permeance for different gases at the same Knudsen numbers is reported with certainty. It is established that this discrepancy relates to a molecule’s effective collision area, which is poorly described in the frameworks of conventional gas permeation models. Two models are proposed for the description of the effect: self-diffusion of penetrate gases due to intermolecular collisions and enhancement of the slip flow contribution due to tangential momentum accommodation growth with the decrease of a molecule’s effective collision area. The best fit parameters for the simultaneous fit of the experimental data with different models for 30 membrane-gas pairs are given.

  12. The interplay between galaxy transition and molecular gas in the next generation of radio facilities

    NASA Astrophysics Data System (ADS)

    Alatalo, Katherine A.; SPOGS Team

    2016-01-01

    The well-known galaxy color bimodality suggests that the paths which galaxies transition from blue, gas-rich spirals to red, gas-poor early-type (elliptical and lenticular) galaxies must be traveled rapidly to explain the dearth of intermediate stage objects. Studying the relationship between the interstellar fuel out of which stars form, and the global changes that galaxies undergo provides a window not only into the paths of transitions that galaxies take, but also how the transition mechanisms can feed back upon the relationship between molecular gas and star formation. I will discuss our results from z=0 transitioning galaxy surveys from CARMA and IRAM, and the ways in which next generation radio telescopes will not only provide detailed insights into the relationship between gas and transition at z=0, but also how this relationship evolves with redshift.

  13. Extremely metal-poor gas at a redshift of 7.

    PubMed

    Simcoe, Robert A; Sullivan, Peter W; Cooksey, Kathy L; Kao, Melodie M; Matejek, Michael S; Burgasser, Adam J

    2012-12-06

    In typical astrophysical environments, the abundance of heavy elements ranges from 0.001 to 2 times the solar value. Lower abundances have been seen in selected stars in the Milky Way's halo and in two quasar absorption systems at redshift z = 3 (ref. 4). These are widely interpreted as relics from the early Universe, when all gas possessed a primordial chemistry. Before now there have been no direct abundance measurements from the first billion years after the Big Bang, when the earliest stars began synthesizing elements. Here we report observations of hydrogen and heavy-element absorption in a spectrum of a quasar at z =  7.04, when the Universe was just 772 million years old (5.6 per cent of its present age). We detect a large column of neutral hydrogen but no corresponding metals (defined as elements heavier than helium), limiting the chemical abundance to less than 1/10,000 times the solar level if the gas is in a gravitationally bound proto-galaxy, or to less than 1/1,000 times the solar value if it is diffuse and unbound. If the absorption is truly intergalactic, it would imply that the Universe was neither ionized by starlight nor chemically enriched in this neighbourhood at z ≈ 7. If it is gravitationally bound, the inferred abundance is too low to promote efficient cooling, and the system would be a viable site to form the predicted but as yet unobserved massive population III stars.

  14. Energy level transitions of gas in a 2D nanopore

    SciTech Connect

    Grinyaev, Yurii V.; Chertova, Nadezhda V.; Psakhie, Sergei G.

    2015-10-27

    An analytical study of gas behavior in a 2D nanopore was performed. It is shown that the temperature dependence of gas energy can be stepwise due to transitions from one size-quantized subband to another. Taking into account quantum size effects results in energy level transitions governed by the nanopore size, temperature and gas density. This effect leads to an abrupt change of gas heat capacity in the nanopore at the above varying system parameters.

  15. Conformational transitions of single polymer adsorption in poor solvent: Wetting transition due to molecular confinement induced line tension.

    PubMed

    Wei, Hsien-Hung; Li, Yen-Ching

    2016-07-01

    We report a theory capable of describing conformational transitions for single polymer adsorption in a poor solvent. We show that an additional molecular confinement effect near the contact line can act exactly like line tension, playing a critical role in the behavior of an absorbed polymer chain. Using this theory, distinct conformational states: desorbed globule (DG), surface attached cap (SAC), and adsorbed lens (AL), can be vividly revealed, resembling the drying-wetting transition of a nanodroplet. But the transitions between these states can behave rather differently from those in the usual wetting transitions. The DG-SAC transition is discrete, occurring at the adsorption threshold when the globule size at the desorbed state is equal to the adsorption blob. The SAC-AL transition is smooth for finite chain lengths, but can change to discontinuous in the infinite chain limit, characterized by the different end-to-end exponent 3/8 and the unique crossover exponent 1/4. Distinctive critical exponents near this transition are also determined, indicating that it is an additional universality class of phase transitions. This work also sheds light on nanodrop spreading, wherein the important role played by line tension might simply be a manifestation of the local molecular confinement near the contact line.

  16. Conformational transitions of single polymer adsorption in poor solvent: Wetting transition due to molecular confinement induced line tension

    NASA Astrophysics Data System (ADS)

    Wei, Hsien-Hung; Li, Yen-Ching

    2016-07-01

    We report a theory capable of describing conformational transitions for single polymer adsorption in a poor solvent. We show that an additional molecular confinement effect near the contact line can act exactly like line tension, playing a critical role in the behavior of an absorbed polymer chain. Using this theory, distinct conformational states: desorbed globule (DG), surface attached cap (SAC), and adsorbed lens (AL), can be vividly revealed, resembling the drying-wetting transition of a nanodroplet. But the transitions between these states can behave rather differently from those in the usual wetting transitions. The DG-SAC transition is discrete, occurring at the adsorption threshold when the globule size at the desorbed state is equal to the adsorption blob. The SAC-AL transition is smooth for finite chain lengths, but can change to discontinuous in the infinite chain limit, characterized by the different end-to-end exponent 3/8 and the unique crossover exponent 1/4. Distinctive critical exponents near this transition are also determined, indicating that it is an additional universality class of phase transitions. This work also sheds light on nanodrop spreading, wherein the important role played by line tension might simply be a manifestation of the local molecular confinement near the contact line.

  17. Transition of RF internal antenna plasma by gas control

    SciTech Connect

    Hamajima, Takafumi; Yamauchi, Toshihiko; Kobayashi, Seiji; Hiruta, Toshihito; Kanno, Yoshinori

    2012-07-11

    The transition between the capacitively coupled plasma (CCP) and the inductively coupled plasma (ICP) was investigated with the internal radio frequency (RF) multi-turn antenna. The transition between them showed the hysteresis curve. The radiation power and the period of the self-pulse mode became small in proportion to the gas pressure. It was found that the ICP transition occurred by decreasing the gas pressure from 400 Pa.

  18. Transition metal catalysis in the generation of natural gas

    SciTech Connect

    Mango, F.D.

    1995-12-31

    The view that natural gas is thermolytic, coming from decomposing organic debris, has remained almost unchallenged for nearly half a century. Disturbing contradictions exist, however: Oil is found at great depth, at temperatures where only gas should exist and oil and gas deposits show no evidence of the thermolytic debris indicative of oil decomposing to gas. Moreover, laboratory attempts to duplicate the composition of natural gas, which is typically between 60 and 95+ wt% methane in C{sub 1}-C{sub 4}, have produced insufficient amounts of methane (10 to 60%). It has been suggested that natural gas may be generated catalytically, promoted by the transition metals in carbonaceous sedimentary rocks. This talk will discuss experimental results that support this hypothesis. Various transition metals, as pure compounds and in source rocks, will be shown to generate a catalytic gas that is identical to natural gas. Kinetic results suggest robust catalytic activity under moderate catagenetic conditions.

  19. Gas flow with straight transition line

    NASA Technical Reports Server (NTRS)

    Ovsiannikov, L V

    1951-01-01

    An investigation was conducted on the limiting case of a gas flow when the constant pressure in the surrounding medium is exactly equal to the critical pressure for the given initial state of the gas.

  20. The consequences of poor communication during transitions from hospital to skilled nursing facility: a qualitative study.

    PubMed

    King, Barbara J; Gilmore-Bykovskyi, Andrea L; Roiland, Rachel A; Polnaszek, Brock E; Bowers, Barbara J; Kind, Amy J H

    2013-07-01

    To examine how skilled nursing facility (SNF) nurses transition the care of individuals admitted from hospitals, the barriers they experience, and the outcomes associated with variation in the quality of transitions. Qualitative study using grounded dimensional analysis, focus groups, and in-depth interviews. Five Wisconsin SNFs. Twenty-seven registered nurses. Semistructured questions guided the focus group and individual interviews. SNF nurses rely heavily on written hospital discharge communication to transition individuals into the SNF effectively. Nurses cited multiple inadequacies of hospital discharge information, including regular problems with medication orders (including the lack of opioid prescriptions for pain), little psychosocial or functional history, and inaccurate information regarding current health status. These communication inadequacies necessitated repeated telephone clarifications, created care delays (including delays in pain control), increased SNF staff stress, frustrated individuals and family members, contributed directly to negative SNF facility image, and increased risk of rehospitalization. SNF nurses identified a specific list of information and components that they need to facilitate a safe, high-quality transition. Nurses note multiple deficiencies in hospital-to-SNF transitions, with poor quality discharge communication being identified as the major barrier to safe and effective transitions. This information should be used to refine and support the dissemination of evidence-based interventions that support transitions of care, including the Interventions to Reduce Acute Care Transfers program. © 2013, Copyright the Authors Journal compilation © 2013, The American Geriatrics Society.

  1. Demonstration and evaluation of gas turbine transit buses

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The Gas Turbine Transit Bus Demonstration Program was designed to demonstrate and evaluate the operation of gas turbine engines in transit coaches in revenue service compared with diesel powered coaches. The main objective of the program was to accelerate development and commercialization of automotive gas turbines. The benefits from the installation of this engine in a transit coach were expected to be reduced weight, cleaner exhaust emissions, lower noise levels, reduced engine vibration and maintenance requirements, improved reliability and vehicle performance, greater engine braking capability, and superior cold weather starting. Four RTS-II advanced design transit coaches were converted to gas turbine power using engines and transmissions. Development, acceptance, performance and systems tests were performed on the coaches prior to the revenue service demonstration.

  2. CAUSES OF POOR SEALANT PERFORMANCE IN SOIL-GAS- RESISTANT FOUNDATIONS

    EPA Science Inventory

    The paper discusses causes of poor sealant performance in soil-gas-resistant foundations. ealants for radon-resistant foundation construction must seal the gap between concrete sections. odern sealants have such low permeability that seal performance depends only on the permeabil...

  3. CAUSES OF POOR SEALANT PERFORMANCE IN SOIL-GAS- RESISTANT FOUNDATIONS

    EPA Science Inventory

    The paper discusses causes of poor sealant performance in soil-gas-resistant foundations. ealants for radon-resistant foundation construction must seal the gap between concrete sections. odern sealants have such low permeability that seal performance depends only on the permeabil...

  4. Deflagration to detonation transition in combustible gas mixtures

    SciTech Connect

    Smirnov, N.N.; Panfilov, I.I.

    1995-04-01

    This paper presents the results of a computational investigation of the process of deflagration to detonation transition in a combustible gas mixture. The type of combustion (i.e., deflagration or detonation) supported by a two-step reaction scheme is studied as a function of the activation energies. It is shown that both a deflagration to detonation transition and a deflagration wave that lags behind a leading shock are possible. Two types of deflagration to detonation transitions are found theoretically: initiation of detonation from the flame zone and initiation of detonation along a contact discontinuity in the compressed gas near the primary shock wave.

  5. The transition from good to poor health: an econometric study of the older population.

    PubMed

    Buckley, Neil J; Denton, Frank T; Robb, A Leslie; Spencer, Byron G

    2004-09-01

    This is a study of the influence of socioeconomic factors on the state of health of older Canadians. Three years of panel data from the Survey of Labour and Income Dynamics are used to model the transition probabilities between good and poor health. Care is taken to avoid the problem of endogeneity of income in modelling its effects, and to adjust reported income to free it from its strong association with age at the time of the survey. Of particular note are the significant effects found for income, in spite of universal public health care coverage. Significant effects are found also for age, education, and other variables.

  6. Transition from magma dominant to magma poor rifting along the Nova Scotia Continental Margin

    NASA Astrophysics Data System (ADS)

    Lau, K. H.; Louden, K. E.; Nedimović, M. R.; Whitehead, M.; Farkas, A.; Watremez, L.; Dehler, S. A.

    2011-12-01

    Passive margins have been characterized as magma-dominant (volcanic) or magma-poor (non-volcanic). However, the conditions under which margins might switch states are not well understood as they typically have been studied as end member examples in isolation to each other. The Nova Scotia (NS) continental margin, however, offers an opportunity to study the nature of such a transition between the magma-dominant US East Coast margin to the south and the magma-poor Newfoundland margin to the north within a single rift segment. This transition is evidenced by a clear along-strike reduction in features characteristic of syn-rift volcanism from south-to-north along the NS margin, such as the weakening of the East Coast Magnetic Anomaly (ECMA) and the coincident disappearance of seaward dipping reflector sequences (SDRS) on multichannel seismic (MCS) reflection profiles. Results from recent industry MCS profiles along and across the margin suggest a potentially narrow magma-dominant to magma-poor along-strike transition between the southern and the central NS margin. Such a transition is broadly consistent with results of several widely-spaced, across-strike ocean bottom seismometer (OBS) wide-angle profiles. In the southern region, the crustal structure exhibits a narrow (~120-km wide) ocean-continent transition (OCT) with a high velocity (7.2 km/s) lower crust, interpreted as a gabbro-rich underplated melt, beneath the SDRS and the ECMA, similar to crustal models across the US East Coast. In contrast, profiles across the central and northern margin contain a much wider OCT (150-200-km wide) underlain by a low velocity mantle layer (7.3-7.9 km/s), interpreted as partially serpentinized olivine, which is similar to the magma-poor Newfoundland margin to the north. However, the central-to-northern OBS profiles also exhibit significant variations within the OCT and the along-strike continuity of these OCT structures is not yet clear. In November 2010, we acquired, in the

  7. Uniform electron gas for transition metals: Input parameters

    SciTech Connect

    Rose, J.H. ); Shore, H.B. )

    1993-12-15

    Input parameters are reported for the theory of ideal metals, a uniform electron-gas model of the elemental transition metals. These input parameters, the electron density, and the bonding valence,'' have been given previously for the 3[ital d] and 4[ital d] series of transition metals. Here, we extend our work based on recent calculations of Sigalas [ital et] [ital al]. [Phys. Rev. B 45, 5777 (1992)] to include the 5[ital d] series. We have also calculated the cohesive energies of the 5[ital d] transition metals using the theory of ideal metals with these parameters. The calculations agree with experiment to within [plus minus]25%.

  8. Structural and phase transitions of one and two polymer mushrooms in poor solvent

    NASA Astrophysics Data System (ADS)

    Yang, Delian; Wang, Qiang

    2014-05-01

    Using the recently proposed fast lattice Monte Carlo (FLMC) simulations and the corresponding lattice self-consistent field (LSCF) calculations based on the same model system, where multiple occupancy of lattice sites is allowed [Q. Wang, Soft Matter 5, 4564 (2009); Q. Wang, Soft Matter 5, 6206 (2010)], we studied the coil-globule transition (CGT) of one-mushroom systems and the fused-separated transition (FST) of two-mushroom systems, where a polymer mushroom is formed by a group of n homopolymer chains each of N segments end-grafted at the same point onto a flat substrate and immersed in a poor solvent. With our soft potential that allows complete particle overlapping, LSCF theory neglecting the system fluctuations/correlations becomes exact in the limit of n → ∞, and FLMC results approach LSCF predictions with increasing n. Using LSCF calculations, we systematically constructed the phase diagrams of one- and two-mushroom systems. A second-order symmetric-asymmetric transition (SAT) was found in the globule state of one-mushroom systems, where the rotational symmetry around the substrate normal passing through the grafting point is broken in each individual configuration but preserved by the degeneracy of different orientations of these asymmetric configurations. Three different states were also found in two-mushroom systems: separated coils, separated globules, and fused globule. We further studied the coupling between FST in two-mushroom systems and CGT and SAT of each mushroom. Finally, direct comparisons between our simulation and theoretical results, without any parameter-fitting, unambiguously and quantitatively revealed the fluctuation/correlation effects on these phase transitions.

  9. CYB5R1 links epithelial-mesenchymal transition and poor prognosis in colorectal cancer

    PubMed Central

    Lamprecht, Sebastian; Engel, Jutta; Hermeking, Heiko; Kirchner, Thomas; Horst, David

    2016-01-01

    Colorectal cancers show significant tumor cell heterogeneity within the same core genetic background. Epithelial-mesenchymal transition (EMT) is an important functional aspect of this heterogeneity and hallmark of colorectal cancer progression. Here, we identify CYB5R1, an enzyme involved in oxidative stress protection and drug metabolism, as an indicator of EMT in colon cancer. We demonstrate high CYB5R1 expression in colorectal cancer cells undergoing EMT at the infiltrative tumor edge and reveal an extraordinarily strong association of CYB5R1 expression with two core EMT gene expression signatures in a large independent colon cancer data set from The Cancer Genome Atlas (TCGA). Furthermore, we demonstrate that CYB5R1 is required for an infiltrative tumor cell phenotype, and robustly linked with poor prognosis in colorectal cancer. Our findings have important implications for colon cancer cells undergoing EMT and may be exploited for diagnostic and therapeutic purposes. PMID:27120783

  10. The CO Transition from Diffuse Molecular Gas to Dense Clouds

    NASA Astrophysics Data System (ADS)

    Rice, Johnathan S.; Federman, Steven

    2017-06-01

    The atomic to molecular transitions occurring in diffuse interstellar gas surrounding molecular clouds are affected by the local physical conditions (density and temperature) and the radiation field penetrating the material. Our optical observations of CH, CH^{+}, and CN absorption from McDonald Observatory and the European Southern Observatory are useful tracers of this gas and provide the velocity structure needed for analyzing lower resolution ultraviolet observations of CO and H_{2} absorption from Far Ultraviolet Spectroscopic Explorer. We explore the changing environment between diffuse and dense gas by using the column densities and excitation temperatures from CO and H_{2} to determine the gas density. The resulting gas densities from this method are compared to densities inferred from other methods such as C_{2} and CN chemistry. The densities allow us to interpret the trends from the combined set of tracers. Groupings of sight lines, such as those toward h and χ Persei or Chameleon provide a chance for further characterization of the environment. The Chameleon region in particular helps illuminate CO-dark gas, which is not associated with emission from H I at 21 cm or from CO at 2.6 mm. Expanding this analysis to include emission data from the GOT C+ survey allows the further characterization of neutral diffuse gas, including CO-dark gas.

  11. Imaging the Elusive H-poor Gas in the High adf Planetary Nebula NGC 6778

    NASA Astrophysics Data System (ADS)

    García-Rojas, Jorge; Corradi, Romano L. M.; Monteiro, Hektor; Jones, David; Rodríguez-Gil, Pablo; Cabrera-Lavers, Antonio

    2016-06-01

    We present the first direct image of the high-metallicity gas component in a planetary nebula (NGC 6778), taken with the OSIRIS Blue Tunable Filter centered on the O ii λ4649+50 Å optical recombination lines (ORLs) at the 10.4 m Gran Telescopio Canarias. We show that the emission of these faint O ii ORLs is concentrated in the central parts of the planetary nebula and is not spatially coincident either with emission coming from the bright [O iii] λ5007 Å collisionally excited line (CEL) or the bright Hα recombination line. From monochromatic emission line maps taken with VIMOS at the 8.2 m Very Large Telescope, we find that the spatial distribution of the emission from the auroral [O iii] λ4363 line resembles that of the O ii ORLs but differs from nebular [O iii] λ5007 CEL distribution, implying a temperature gradient inside the planetary nebula. The centrally peaked distribution of the O ii emission and the differences with the [O iii] and H i emission profiles are consistent with the presence of an H-poor gas whose origin may be linked to the binarity of the central star. However, determination of the spatial distribution of the ORLs and CELs in other PNe and a comparison of their dynamics are needed to further constrain the geometry and ejection mechanism of the metal-rich (H-poor) component and hence, understand the origin of the abundance discrepancy problem in PNe.

  12. Radial inflow gas turbine engine with advanced transition duct

    SciTech Connect

    Wiebe, David J

    2015-03-17

    A gas turbine engine (10), including: a turbine having radial inflow impellor blades (38); and an array of advanced transition combustor assemblies arranged circumferentially about the radial inflow impellor blades (38) and having inner surfaces (34) that are adjacent to combustion gases (40). The inner surfaces (34) of the array are configured to accelerate and orient, for delivery directly onto the radial inflow impellor blades (38), a plurality of discrete flows of the combustion gases (40). The array inner surfaces (34) define respective combustion gas flow axes (20). Each combustion gas flow axis (20) is straight from a point of ignition until no longer bound by the array inner surfaces (34), and each combustion gas flow axis (20) intersects a unique location on a circumference defined by a sweep of the radial inflow impellor blades (38).

  13. The kinematics and morphology of the H I in gas-poor galaxies

    NASA Astrophysics Data System (ADS)

    Oosterloo, T. A.; Morganti, R.; de Zeeuw, P. T.; McDermid, R. M.; Krajnović, D.; Cappellari, M.; Kenn, F.; Weijmans, A.; Sarzi, M.

    2007-02-01

    We present the results of deep Westerbork Synthesis Radio Telescope observations of the neutral hydrogen in 12 nearby elliptical and lenticular galaxies selected from a representative sample of nearby galaxies that were studied earlier at optical wavelengths with the integral-field spectrograph sauron. The observed objects are field galaxies, or (in two cases) are located in poor-group environments. We detect H I in 70% of the galaxies. This detection rate is much higher than in previous, shallower single-dish surveys, and is similar to that for the ionised gas. The results suggest that at faint detection levels the presence of H I is a relatively common characteristic of field early-type galaxies. The presence of regular disc-like structures is as common as H I in offset clouds and tails. All galaxies where H I is detected also contain ionised gas, whereas no H I is found around galaxies without ionised gas. Galaxies with regular H I discs tend to have strong emission from ionised gas. In these cases, the similar kinematics of the neutral hydrogen and ionised gas suggest that they form one structure. We do not find a trend between the presence of H I and the global age of the stellar population or with the global dynamical characteristics of the galaxies. If fast and slow rotators represent the relics of different formation paths, this does not appear in the presence and characteristics of the H I. The links observed between the large-scale gas and the characteristics on the nuclear scale (e.g. the presence of kinematically decoupled cores and radio continuum emission), suggest that for the majority of the cases the gas is acquired through merging, but the lack of correlation with the stellar-population age suggests that smooth, cold accretion could be an alternative scenario, at least in some galaxies. In either case, the data suggest that early-type galaxies continue to build-up their mass to the present.

  14. Long-term tillage and drainage influences on greenhouse gas fluxes from a poorly-drained soil of central Ohio

    USDA-ARS?s Scientific Manuscript database

    Intensive tillage practices and poorly-drained soils of Midwestern USA are the prime reasons for greenhouse gas (GHG) fluxes from agriculture. The naturally poorly-drained soils prevalent in this region require subsurface drainage for improved aeration and improved crop productivity. Soil surface GH...

  15. Deflagration-to-Detonation Transition Control by Nanosecond Gas Discharges

    DTIC Science & Technology

    2008-04-07

    Report 3. DATES COVERED (From – To) 1 April 2007 - 18 August 09 4. TITLE AND SUBTITLE Deflagration-To- Detonation Transition Control By Nanosecond...SUPPLEMENTARY NOTES 14. ABSTRACT During the current project, an extensive experimental study of detonation initiation by high{voltage...nanosecond gas discharges has been performed in a smooth detonation tube with different discharge chambers and various discharge cell numbers. The chambers

  16. A Culture in Transition: Poor Reading and Writing Ability among Children in South African Townships.

    ERIC Educational Resources Information Center

    Pretorius, E.; Naude, H.

    2002-01-01

    This study examined factors contributing to poor literacy and numeracy development among black South African children ages 5.5 to 7 years. Findings pointed to a conglomerate of factors, namely inadequate visual-motor integration, poor visual analysis and synthesis, poor fine motor development, and inadequate exposure to mediated reading and…

  17. "The University of the Poor": The University of Michigan's Transition from Admitting Impoverished Students to Studying Poverty, 1870-1910

    ERIC Educational Resources Information Center

    Nidiffer, Jana; Bouman, Jeffrey P.

    2004-01-01

    During the late 19th century, universities subtly shifted their efforts from admitting poor students to conducting research on poverty. This transition occurred within a complex historical, sociological, and economic milieu of three national forces: universities' quest for prestige; the relationship of expertise and professionalism to the…

  18. Natural Gas Regulation in Transition: The Effects of Geopolitics and Prerequisites for Change in Transition Economies

    SciTech Connect

    Evans, Meredydd

    2009-01-01

    Natural gas has become a major geopolitical concern in relations among transition countries and other European states. Transition economies have embarked on very different paths in using and regulating natural gas. Countries to the East, like Russia, by and large have undertaken few market-oriented reforms of their natural gas sectors. The new European Union member states have undertaken much broader reforms. These differences often lead to tension. Two factors seem particularly important in understanding when countries may embark on natural gas reforms. The first is energy efficiency, since low energy efficiency can make energy reforms socially and economically difficult. The second is corruption: vested interested and a captive state can play powerful roles in inhibiting reform. The article looks at the arguments behind each of these potential prerequisites for reform, and also examines comparative data on energy intensity and corruption. Interestingly, the countries with the lowest energy intensity and the lowest levels of corruption (and the fastest improvements in these areas) also undertook the most extensive natural gas reforms. The article concludes with a few brief examples of the cost with the status quo.

  19. No tillage and liming reduce greenhouse gas emissions from poorly drained agricultural soils in Mediterranean regions.

    PubMed

    García-Marco, Sonia; Abalos, Diego; Espejo, Rafael; Vallejo, Antonio; Mariscal-Sancho, Ignacio

    2016-10-01

    No tillage (NT) has been associated to increased N2O emission from poorly drained agricultural soils. This is the case for soils with a low permeable Bt horizon, which generates a perched water layer after water addition (via rainfall or irrigation) over a long period of time. Moreover, these soils often have problems of acidity and require liming application to sustain crop productivity; changes in soil pH have large implications for the production and consumption of soil greenhouse gas (GHG) emissions. Here, we assessed in a split-plot design the individual and interactive effects of tillage practices (conventional tillage (CT) vs. NT) and liming (Ca-amendment vs. not-amendment) on N2O and CH4 emissions from poorly drained acidic soils, over a field experiment with a rainfed triticale crop. Soil mineral N concentrations, pH, temperature, moisture, water soluble organic carbon, GHG fluxes and denitrification capacity were measured during the experiment. Tillage increased N2O emissions by 68% compared to NT and generally led to higher CH4 emissions; both effects were due to the higher soil moisture content under CT plots. Under CT, liming reduced N2O emissions by 61% whereas no effect was observed under NT. Under both CT and NT, CH4 oxidation was enhanced after liming application due to decreased Al(3+) toxicity. Based on our results, NT should be promoted as a means to improve soil physical properties and concurrently reduce N2O and CH4 emissions. Raising the soil pH via liming has positive effects on crop yield; here we show that it may also serve to mitigate CH4 emissions and, under CT, abate N2O emissions. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. DISCOVERY OF A GAS-RICH COMPANION TO THE EXTREMELY METAL-POOR GALAXY DDO 68

    SciTech Connect

    Cannon, John M.; Alfvin, Erik D.; Johnson, Megan; Koribalski, Baerbel; McQuinn, Kristen B. W.; Skillman, Evan D.; Bailin, Jeremy; Ford, H. Alyson; Girardi, Léo; Hirschauer, Alec S.; Janowiecki, Steven; Salzer, John J.; Van Sistine, Angela; Dolphin, Andrew; Elson, E. C.; Marigo, Paola; Rosenfield, Philip; Rosenberg, Jessica L.; Venkatesan, Aparna; Warren, Steven R.

    2014-05-20

    We present H I spectral-line imaging of the extremely metal-poor galaxy DDO 68. This system has a nebular oxygen abundance of only ∼3% Z {sub ☉}, making it one of the most metal-deficient galaxies known in the local volume. Surprisingly, DDO 68 is a relatively massive and luminous galaxy for its metal content, making it a significant outlier in the mass-metallicity and luminosity-metallicity relationships. The origin of such a low oxygen abundance in DDO 68 presents a challenge for models of the chemical evolution of galaxies. One possible solution to this problem is the infall of pristine neutral gas, potentially initiated during a gravitational interaction. Using archival H I spectral-line imaging obtained with the Karl G. Jansky Very Large Array, we have discovered a previously unknown companion of DDO 68. This low-mass (M{sub H} {sub I} = 2.8 × 10{sup 7} M {sub ☉}), recently star-forming (SFR{sub FUV} = 1.4 × 10{sup –3} M {sub ☉} yr{sup –1}, SFR{sub Hα} < 7 × 10{sup –5} M {sub ☉} yr{sup –1}) companion has the same systemic velocity as DDO 68 (V {sub sys} = 506 km s{sup –1}; D = 12.74 ± 0.27 Mpc) and is located at a projected distance of ∼42 kpc. New H I maps obtained with the 100 m Robert C. Byrd Green Bank Telescope provide evidence that DDO 68 and this companion are gravitationally interacting at the present time. Low surface brightness H I gas forms a bridge between these objects.

  1. Superfluidity and phase transitions in a resonant Bose gas

    SciTech Connect

    Radzihovsky, Leo; Weichman, Peter B.; Park, Jae I.

    2008-10-15

    The atomic Bose gas is studied across a Feshbach resonance, mapping out its phase diagram, and computing its thermodynamics and excitation spectra. It is shown that such a degenerate gas admits two distinct atomic and molecular superfluid phases, with the latter distinguished by the absence of atomic off-diagonal long-range order, gapped atomic excitations, and deconfined atomic {pi}-vortices. The properties of the molecular superfluid are explored, and it is shown that across a Feshbach resonance it undergoes a quantum Ising transition to the atomic superfluid, where both atoms and molecules are condensed. In addition to its distinct thermodynamic signatures and deconfined half-vortices, in a trap a molecular superfluid should be identifiable by the absence of an atomic condensate peak and the presence of a molecular one.

  2. Growth rate and transition to turbulence of a gas curtain

    SciTech Connect

    Vorobieff, P.; Rightley, P.; Benjamin, R.

    1997-09-01

    The authors conduct shock-tube experiments to investigate Richtmyer-Meshkov (RM) instability of a narrow curtain of heavy gas (SF{sub 6}) embedded in lighter gas (air). Initial perturbations of the curtain can be varied, producing different flow patterns in the subsequent evolution of the curtain. Multiple-exposure video flow visualization provides images of the growth of the instability and its transition to turbulence, making it possible to extract quantitative information such as the width of the perturbed curtain. They demonstrate that the width of the curtain with initial perturbation on the downstream side is non-monotonic. As the initial perturbation undergoes phase inversion, the width of the curtain actually decreases before beginning to grow as the RM instability evolves.

  3. Gas sensor based on metal-insulator transition in VO2 nanowire thermistor.

    PubMed

    Strelcov, Evgheni; Lilach, Yigal; Kolmakov, Andrei

    2009-06-01

    Using temperature driven sharp metal-insulator phase transition in single crystal VO(2) nanowires, the realization of a novel gas sensing concept has been tested. Varying the temperature of the nanowire close to the transition edge, the conductance of the nanowire becomes extremely responsive to the tiny changes in molecular composition, pressure, and temperature of the ambient gas environment. This gas sensing analog of the transition edge sensor radiometry used in astrophysics opens new opportunities in gas sensorics.

  4. The Diamagnetic Phase Transition of Dense Electron Gas: Astrophysical Applications

    NASA Astrophysics Data System (ADS)

    Wang, Zhaojun; Lü, Guoliang; Zhu, Chunhua; Wu, Baoshan

    2016-10-01

    Neutron stars are ideal astrophysical laboratories for testing theories of the de Haas-van Alphen effect and diamagnetic phase transition which is associated with magnetic domain formation. The “magnetic interaction” between delocalized magnetic moments of electrons (the Shoenberg effect), can result in an effect of the diamagnetic phase transition into domains of alternating magnetization (Condon's domains). Associated with the domain formation are prominent magnetic field oscillation and anisotropic magnetic stress which may be large enough to fracture the crust of magnetar with a super-strong field. Even if the fracture is impossible as in “low-field” magnetar, the depinning phase transition of domain wall (DW) motion driven by low field rate (mainly due to the Hall effect) in the randomly perturbed crust can result in a catastrophically variation of magnetic field. This intermittent motion, similar to the avalanche process, makes the Hall effect be dissipative. These qualitative consequences about magnetized electron gas are consistent with observations of magnetar emission, and especially the threshold critical dynamics of driven DW can partially overcome the difficulties of “low-field” magnetar bursts and the heating mechanism of transient, or “outbursting” magnetar.

  5. THE EVOLUTION OF INNER DISK GAS IN TRANSITION DISKS

    SciTech Connect

    Hoadley, K.; France, K.; McJunkin, M.; Alexander, R. D.; Schneider, P. C.

    2015-10-10

    Investigating the molecular gas in the inner regions of protoplanetary disks (PPDs) provides insight into how the molecular disk environment changes during the transition from primordial to debris disk systems. We conduct a small survey of molecular hydrogen (H{sub 2}) fluorescent emission, using 14 well-studied Classical T Tauri stars at two distinct dust disk evolutionary stages, to explore how the structure of the inner molecular disk changes as the optically thick warm dust dissipates. We simulate the observed Hi-Lyman α-pumped H{sub 2} disk fluorescence by creating a 2D radiative transfer model that describes the radial distributions of H{sub 2} emission in the disk atmosphere and compare these to observations from the Hubble Space Telescope. We find the radial distributions that best describe the observed H{sub 2} FUV emission arising in primordial disk targets (full dust disk) are demonstrably different than those of transition disks (little-to-no warm dust observed). For each best-fit model, we estimate inner and outer disk emission boundaries (r{sub in} and r{sub out}), describing where the bulk of the observed H{sub 2} emission arises in each disk, and we examine correlations between these and several observational disk evolution indicators, such as n{sub 13–31}, r{sub in,} {sub CO}, and the mass accretion rate. We find strong, positive correlations between the H{sub 2} radial distributions and the slope of the dust spectral energy distribution, implying the behavior of the molecular disk atmosphere changes as the inner dust clears in evolving PPDs. Overall, we find that H{sub 2} inner radii are ∼4 times larger in transition systems, while the bulk of the H{sub 2} emission originates inside the dust gap radius for all transitional sources.

  6. Distribution of the Transit Flow in the Rotor of a Gas Centrifuge

    NASA Astrophysics Data System (ADS)

    Aleksandrov, O. E.

    2016-09-01

    The present work is devoted to computation of the distribution of the transit flow in the rotor of a separation gas centrifuge. The existing transit-flow models have been considered, the equation to find the transit flow has been obtained, and the basic properties of the transit flow have been analyzed. The general equation for the transit-flow distribution has been obtained, and the transit-flow distribution for a simplified scheme of feed supply, extraction, and waste has been calculated.

  7. Morphology, structure, and properties of Cu-poor and Cu-rich Cu(In,Ga)Se2 films partially selenized using H2Se gas

    NASA Astrophysics Data System (ADS)

    Han, Anjun; Huang, Yongliang; Liu, Xiaohui; Xian, Wang; Meng, Fanying; Liu, Zhengxin

    2016-11-01

    Cu-poor and Cu-rich metallic precursors were prepared by cosputtering from In and Cu-Ga alloy targets and then partially selenized using H2Se gas. The properties of Cu(In,Ga)Se2 (CIGS) films are comparatively studied and the phase transition process is analyzed. The cosputtered metallic precursor has a rough morphology mostly covered by large In-rich nodules. After selenization, a large number of crumblike InSe grains were formed from the nodules on the surface of the Cu-rich film, whereas the Cu-poor film shows a dense surface. The selenized films comprise CIGS, Cu9(In,Ga)4 intermetallic, and the InSe phases. The proportion of the Cu9(In,Ga)4 phase in the Cu-rich film is more than that in the Cu-poor film. After annealing, the residual Cu9(In,Ga)4 of the Cu-poor film is eliminated. A negligible effect of Cu/(In+Ga) on the grain size can be observed. The CIGS solar cell with an efficiency of 15.1% was prepared by this method.

  8. The VOrtex Ring Transit EXperiment (VORTEX) GAS project

    NASA Technical Reports Server (NTRS)

    Bilen, Sven G.; Langenderfer, Lynn S.; Jardon, Rebecca D.; Cutlip, Hansford H.; Kazerooni, Alexander C.; Thweatt, Amber L.; Lester, Joseph L.; Bernal, Luis P.

    1995-01-01

    Get Away Special (GAS) payload G-093, also called VORTEX (VOrtex Ring Transit EXperiment), is an investigation of the propagation of a vortex ring through a liquid-gas interface in microgravity. This process results in the formation of one or more liquid droplets similar to earth based liquid atomization systems. In the absence of gravity, surface tension effects dominate the drop formation process. The Shuttle's microgravity environment allows the study of the same fluid atomization processes as using a larger drop size than is possible on Earth. This enables detailed experimental studies of the complex flow processes encountered in liquid atomization systems. With VORTEX, deformations in both the vortex ring and the fluid surface will be measured closely for the first time in a parameters range that accurately resembles liquid atomization. The experimental apparatus will record images of the interactions for analysis after the payload has been returned to earth. The current design of the VORTEX payload consists of a fluid test cell with a vortex ring generator, digital imaging system, laser illumination system, computer based controller, batteries for payload power, and an array of housekeeping and payload monitoring sensors. It is a self-contained experiment and will be flown on board the Space Shuttle in a 5 cubic feet GAS canister. The VORTEX Project is entirely run by students at the University of Michigan but is overseen by a faculty advisor acting as the payload customer and the contact person with NASA. This paper summarizes both the technical and programmatic aspects of the VORTEX Project.

  9. Low expression of long non-coding RNA GAS5 is associated with poor prognosis of patients with thyroid cancer.

    PubMed

    Guo, Ling-Ji; Zhang, Shu; Gao, Bo; Jiang, Yan; Zhang, Xiao-Hua; Tian, Wu-Guo; Hao, Shuai; Zhao, Jian-Jie; Zhang, Gang; Hu, Chun-Yan; Yan, Jie; Luo, Dong-Lin

    2017-06-01

    The study aims to investigate the role of long non-coding RNA (lncRNA) GAS5 in the diagnosis and prognosis of patients suffering from thyroid cancer (TC). A total of 212 patients with TC and 61 patients with benign thyroid tumor were enrolled in the study. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied to detect the lncRNA GAS5 expression in TC and benign tumor tissues. All TC patients were categorized into high-risk and low-risk groups according to the MACIS, AGES and AMES prognostic scoring system. A 5-year follow-up was conducted in order to determine the disease free survival (DFS) rates and overall survival (OS) rates. The associations between lncRNA GAS5 expression and prognosis of TC patients were analyzed by The Kaplan-Meier survival curves and the Cox regression models. There was a decrease in the lncRNA GAS5 expression in TC tissues in comparison to benign tumor tissues. Expression of lncRNA GAS5 showed significant association with tumor node metastasis (TNM) staging, lymph node metastasis and the multiple cancer foci of TC. AMES high-risk patients showed a decreased expression of lncRNA GAS5 expression than the AMES low-risk patients. The AGES and MACIS high-risk patients showed lower lncRNA GAS5 expression than low-risk patients. The survival rate of TC patients with high lncRNA GAS5 expression was higher than that of TC patients with low lncRNA GAS5 expression during the DFS and OS periods. Cox regression analysis indicated that lncRNA GAS5 expression, TNM staging, lymph node metastasis and multiple cancer foci were independent risk factors for poor prognosis in TC patients. LncRNA GAS5 may be closely related to the diagnosis and prognosis of TC. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Meta-Analysis of Microarray Data Identifies GAS6 Expression as an Independent Predictor of Poor Survival in Ovarian Cancer

    PubMed Central

    Tse, Brian; Jacob, Francis; Caduff, Rosmarie; Fink, Daniel; Goldstein, Darlene R.; Heinzelmann-Schwarz, Viola

    2013-01-01

    Seeking new biomarkers for epithelial ovarian cancer, the fifth most common cause of death from all cancers in women and the leading cause of death from gynaecological malignancies, we performed a meta-analysis of three independent studies and compared the results in regard to clinicopathological parameters. This analysis revealed that GAS6 was highly expressed in ovarian cancer and therefore was selected as our candidate of choice. GAS6 encodes a secreted protein involved in physiological processes including cell proliferation, chemotaxis, and cell survival. We performed immunohistochemistry on various ovarian cancer tissues and found that GAS6 expression was elevated in tumour tissue samples compared to healthy control samples (P < 0.0001). In addition, GAS6 expression was also higher in tumours from patients with residual disease compared to those without. Our data propose GAS6 as an independent predictor of poor survival, suggesting GAS6, both on the mRNA and on the protein level, as a potential biomarker for ovarian cancer. In clinical practice, the staining of a tumour biopsy for GAS6 may be useful to assess cancer prognosis and/or to monitor disease progression. PMID:23878800

  11. WASP-80b: a gas giant transiting a cool dwarf

    NASA Astrophysics Data System (ADS)

    Triaud, A. H. M. J.; Anderson, D. R.; Collier Cameron, A.; Doyle, A. P.; Fumel, A.; Gillon, M.; Hellier, C.; Jehin, E.; Lendl, M.; Lovis, C.; Maxted, P. F. L.; Pepe, F.; Pollacco, D.; Queloz, D.; Ségransan, D.; Smalley, B.; Smith, A. M. S.; Udry, S.; West, R. G.; Wheatley, P. J.

    2013-03-01

    We report the discovery of a planet transiting the star WASP-80 (1SWASP J201240.26-020838.2; 2MASS J20124017-0208391; TYC 5165-481-1; BPM 80815; V = 11.9, K = 8.4). Our analysis shows this is a 0.55 ± 0.04 Mjup, 0.95 ± 0.03 Rjup gas giant on a circular 3.07 day orbit around a star with a spectral type between K7V and M0V. This system produces one of the largest transit depths so far reported, making it a worthwhile target for transmission spectroscopy. We find a large discrepancy between the vsini⋆ inferred from stellar line broadening and the observed amplitude of the Rossiter-McLaughlin effect. This can be understood either by an orbital plane nearly perpendicular to the stellar spin or by an additional, unaccounted for source of broadening. Using WASP-South photometric observations, from Sutherland (South Africa), confirmed with the 60 cm TRAPPIST robotic telescope, EulerCam, and the CORALIE spectrograph on the Swiss 1.2 m Euler Telescope, and HARPS on the ESO 3.6 m (Prog ID 089.C-0151), all three located at La Silla Observatory, Chile.Radial velocity and photometric data are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A80

  12. From magma-poor Ocean Continent Transitions to steady state oceanic spreading: the balance between tectonic and magmatic processes

    NASA Astrophysics Data System (ADS)

    Gillard, Morgane; Manatschal, Gianreto; Autin, Julia; Decarlis, Alessandro; Sauter, Daniel

    2016-04-01

    The evolution of magma-poor rifted margins is linked to the development of a transition zone whose basement is neither clearly continental nor oceanic. The development of this Ocean-Continent Transition (OCT) is generally associated to the exhumation of serpentinized mantle along one or several detachment faults. That model is supported by numerous observations (IODP wells, dredges, fossil margins) and by numerical modelling. However, if the initiation of detachment faults in a magma-poor setting tends to be better understood by numerous studies in various area, the transition with the first steady state oceanic crust and the associated processes remain enigmatic and poorly studied. Indeed, this latest stage of evolution appears to be extremely gradual and involves strong interactions between tectonic processes and magmatism. Contrary to the proximal part of the exhumed domain where we can observe magmatic activity linked to the exhumation process (exhumation of gabbros, small amount of basalts above the exhumed mantle), in the most distal part the magmatic system appears to be independent and more active. In particular, we can observe large amounts of extrusive material above a previously exhumed and faulted basement (e.g. Alps, Australia-Antarctica margins). It seems that some faults can play the role of feeder systems for the magma in this area. Magmatic underplating is also important, as suggested by basement uplift and anomalously thick crust (e.g. East Indian margin). It results that the transition with the first steady state oceanic crust is marked by the presence of a hybrid basement, composed by exhumed mantle and magmatic material, whose formation is linked to several tectonic and magmatic events. One could argue that this basement is not clearly different from an oceanic basement. However, we consider that true, steady state oceanic crust only exists, if the entire rock association forming the crust is created during a single event, at a localized

  13. Metallicity inhomogeneities in local star-forming galaxies as a sign of recent metal-poor gas accretion

    SciTech Connect

    Sánchez Almeida, J.; Morales-Luis, A. B.; Muñoz-Tuñón, C.; Méndez-Abreu, J.; Elmegreen, D. M.; Elmegreen, B. G. E-mail: abml@iac.es E-mail: elmegreen@vassar.edu E-mail: jma20@st-andrews.ac.uk

    2014-03-01

    We measure the oxygen metallicity of the ionized gas along the major axis of seven dwarf star-forming galaxies. Two of them, SDSSJ1647+21 and SDSSJ2238+14, show ≅0.5 dex metallicity decrements in inner regions with enhanced star formation activity. This behavior is similar to the metallicity drop observed in a number of local tadpole galaxies by Sánchez Almeida et al., and was interpreted as showing early stages of assembling in disk galaxies, with the star formation sustained by external metal-poor gas accretion. The agreement with tadpoles has several implications. (1) It proves that galaxies other than the local tadpoles present the same unusual metallicity pattern. (2) Our metallicity inhomogeneities were inferred using the direct method, thus discarding systematic errors usually attributed to other methods. (3) Taken together with the tadpole data, our findings suggest a threshold around one-tenth the solar value for the metallicity drops to show up. Although galaxies with clear metallicity drops are rare, the physical mechanism responsible for them may sustain a significant part of the star formation activity in the local universe. We argue that the star formation dependence of the mass-metallicity relationship, as well as other general properties followed by most local disk galaxies, is naturally interpreted as side effects of pristine gas infall. Alternatives to the metal-poor gas accretion are examined as well.

  14. WASP-36b: A NEW TRANSITING PLANET AROUND A METAL-POOR G-DWARF, AND AN INVESTIGATION INTO ANALYSES BASED ON A SINGLE TRANSIT LIGHT CURVE

    SciTech Connect

    Smith, A. M. S.; Anderson, D. R.; Hellier, C.; Maxted, P. F. L.; Smalley, B.; Southworth, J.; Collier Cameron, A.; Gillon, M.; Jehin, E.; Lendl, M.; Queloz, D.; Triaud, A. H. M. J.; Pepe, F.; Segransan, D.; Udry, S.; West, R. G.; Barros, S. C. C.; Pollacco, D.; Street, R. A.

    2012-04-15

    We report the discovery, from WASP and CORALIE, of a transiting exoplanet in a 1.54 day orbit. The host star, WASP-36, is a magnitude V = 12.7, metal-poor G2 dwarf (T{sub eff} = 5959 {+-} 134 K), with [Fe/H] =-0.26 {+-} 0.10. We determine the planet to have mass and radius, respectively, 2.30 {+-} 0.07 and 1.28 {+-} 0.03 times that of Jupiter. We have eight partial or complete transit light curves, from four different observatories, which allow us to investigate the potential effects on the fitted system parameters of using only a single light curve. We find that the solutions obtained by analyzing each of these light curves independently are consistent with our global fit to all the data, despite the apparent presence of correlated noise in at least two of the light curves.

  15. A Simple Model for Fine Structure Transitions in Alkali-Metal Noble-Gas Collisions

    DTIC Science & Technology

    2015-03-01

    A SIMPLE MODEL FOR FINE STRUCTURE TRANSITIONS IN ALKALI - METAL NOBLE-GAS COLLISIONS THESIS Joseph A. Cardoza, Captain, USAF AFIT-ENP-MS-15-M-079... ALKALI - METAL NOBLE-GAS COLLISIONS THESIS Presented to the Faculty Department of Engineering Physics Graduate School of Engineering and Management Air...AFIT-ENP-MS-15-M-079 A SIMPLE MODEL FOR FINE STRUCTURE TRANSITIONS IN ALKALI - METAL NOBLE-GAS COLLISIONS Joseph A. Cardoza, BS Captain, USAF Committee

  16. Cooling air recycling for gas turbine transition duct end frame and related method

    DOEpatents

    Cromer, Robert Harold; Bechtel, William Theodore; Sutcu, Maz

    2002-01-01

    A method of cooling a transition duct end frame in a gas turbine includes the steps of a) directing cooling air into the end frame from a region external of the transition duct and the impingement cooling sleeve; and b) redirecting the cooling air from the end frame into the annulus between the transition duct and the impingement cooling sleeve.

  17. Overexpression of RACK1 Promotes Metastasis by Enhancing Epithelial-Mesenchymal Transition and Predicts Poor Prognosis in Human Glioma

    PubMed Central

    Lv, Qiao-Li; Huang, Yuan-Tao; Wang, Gui-Hua; Liu, Yan-Ling; Huang, Jin; Qu, Qiang; Sun, Bao; Hu, Lei; Cheng, Lin; Chen, Shu-Hui; Zhou, Hong-Hao

    2016-01-01

    Emerging studies show that dysregulation of the receptor of activated protein kinase C1 (RACK1) plays a crucial role in tumorigenesis and progression of various cancers. However, the biological function and underlying mechanism of RACK1 in glioma remains poorly defined. Here, we found that RACK1 was significantly up-regulated in glioma tissues compared with normal brain tissues, being closely related to clinical stage of glioma both in mRNA and protein levels. Moreover, Kaplan-Meier analysis demonstrated that patients with high RACK1 expression had a poor prognosis (p = 0.0062, HR = 1.898, 95% CI: 1.225–3.203). In vitro functional assays indicated that silencing of RACK1 could dramatically promote apoptosis and inhibit cell proliferation, migration, and invasion of glioma cells. More importantly, knockdown of RACK1 led to a vast accumulation of cells in G0/G1 phase and their reduced proportions at the S phase by suppressing the expression of G1/S transition key regulators Cyclin D1 and CDK6. Additionally, this forced down-regulation of RACK1 significantly suppressed migration and invasion via inhibiting the epithelial-mesenchymal transition (EMT) markers, such as MMP2, MMP9, ZEB1, N-Cadherin, and Integrin-β1. Collectively, our study revealed that RACK1 might act as a valuable prognostic biomarker and potential therapeutic target for glioma. PMID:27763568

  18. Conformation transitions of a single polyelectrolyte chain in a poor solvent: a replica-exchange lattice Monte-Carlo study.

    PubMed

    Wang, Lang; Wang, Zheng; Jiang, Run; Yin, Yuhua; Li, Baohui

    2017-03-15

    The thermodynamic behaviors of a strongly charged polyelectrolyte chain in a poor solvent are studied using replica-exchange Monte-Carlo simulations on a lattice model, focusing on the effects of finite chain length and the solvent quality on the chain conformation and conformation transitions. The neutralizing counterions and solvent molecules are considered explicitly. The thermodynamic quantities that vary continuously with temperature over a wide range are computed using the multiple histogram reweighting method. Our results suggest that the strength of the short-range hydrophobic interaction, the chain length, and the temperature of the system, characterized by ε, N, and T, respectively, are important parameters that control the conformations of a charged chain. When ε is moderate, the competition between the electrostatic energy and the short-range hydrophobic interaction leads to rich conformations and conformation transitions for a longer chain with a fixed length. Our results have unambiguously demonstrated the stability of the n-pearl-necklace structures, where n has a maximum value and decreases with decreasing temperature. The maximum n value increases with increasing chain length. Our results have also demonstrated the first-order nature of the conformation transitions between the m-pearl and the (m-1)-pearl necklaces. With the increase of ε, the transition temperature increases and the first-order feature becomes more pronounced. It is deduced that at the thermodynamic limit of infinitely long chain length, the conformational transitions between the m-pearl and the (m-1)-pearl necklaces may remain first order when ε > 0 and m = 2 or 3. Pearl-necklace conformations cannot be observed when either ε is too large or N is too small. To observe a pearl-necklace conformation, the T value needs to be carefully chosen for simulations performed at only a single temperature.

  19. The X-ray emitting gas in poor clusters with central dominant galaxies

    NASA Technical Reports Server (NTRS)

    Kriss, G. A.; Cioffi, D. F.; Canizares, C. R.

    1983-01-01

    The 12 clusters detected in the present study by the Einstein Observatory's X-ray imaging proportional counter show X-ray emission centered on the dominant galaxy in all cases. Comparison of the deduced distribution of binding mass with the light distribution of the central galaxies of four clusters indicates that the mass/luminosity ratio rises to over 200 solar masses/solar luminosity in the galaxy halos. These halos must therefore, like the clusters themselves, posses dark matter. The X-ray data clearly show that the dominant galaxies sit at the bottoms of the poor cluster gravitational potential wells, suggesting a similar origin for dominant galaxies in poor and rich clusters, perhaps through the merger and cannibalism of cluster galaxies. It is the luminosity of the distended cD envelope that reflects the relative wealth of the cluster environment.

  20. Microbial keratitis secondary to unintended poor compliance with scleral gas-permeable contact lenses.

    PubMed

    Zimmerman, Aaron B; Marks, Amanda

    2014-01-01

    To report a case of neurotrophic keratitis in which scleral contact lenses improved vision from 20/100 to 20/20, however, due to poor lens care, an incident of microbial keratitis developed. A 64-year-old man with an ocular history of neurotrophic keratitis secondary to herpes simplex in each eye was successfully fit with scleral lenses. He subsequently developed microbial keratitis due to a number of risk factors. The lesion was culture negative, yet was very responsive to treatment with moxifloxacin. The lesion fully healed, and the patient did not suffer additional vision loss. This case demonstrates the ability of scleral lenses to correct visual impairments secondary to poor epithelial integrity and illustrates the importance of the practitioner providing detailed lens care instruction.

  1. Impaired transit and tolerance of intestinal gas in the irritable bowel syndrome

    PubMed Central

    Serra, J; Azpiroz, F; Malagelada, J

    2001-01-01

    Abstract Background—Patients with irritable bowel syndrome (IBS) frequently complain of excessive gas but their fasting volume of intestinal gas is apparently normal. We hypothesised that the pathophysiological mechanism involved may be impairment of intestinal gas transit. Aim—To investigate intestinal gas transit and tolerance in IBS patients compared with healthy subjects. Methods—A gas mixture (N2, O2, and CO2 in venous proportions) was infused into the jejunum of 20 patients with IBS and 20 healthy controls at 12 ml/min for four hours. Gas evacuation, initially flatus from the anus (two hours) and then intrarectally (two hours), was continuously recorded. Symptom perception (0-6 scale) and abdominal distension were measured at 10 minute intervals. Results—After two hours of external gas (flatus) collection, 18 of 20 IBS patients had developed gas retention (>400 ml), increased gastrointestinal symptoms (score >3), or abdominal distension (>3 mm girth increment) compared with only four of 20 control subjects. During intrarectal gas collection, 13 of 17 patients still exhibited abnormal responses. Conclusion—A large proportion of patients with IBS can be shown to have impaired transit and tolerance of intestinal gas loads. This anomaly may represent a possible mechanism of IBS symptoms, specifically pain and bloating.


Keywords: intestinal gas; irritable bowel syndrome; intestinal transit; visceral sensitivity; abdominal distension PMID:11115817

  2. Very metal-poor galaxies: ionized gas kinematics in nine objects

    NASA Astrophysics Data System (ADS)

    Moiseev, A. V.; Pustilnik, S. A.; Kniazev, A. Y.

    2010-07-01

    The study of ionized gas morphology and kinematics in nine extremely metal-deficient (XMD) galaxies with the scanning Fabry-Perot interferometer on the Special Astrophysical Observatory (SAO) 6-m telescope is presented. Some of these very rare objects (with currently known range of O/H of 7.12 < 12 + log(O/H) < 7.65, or ) are believed to be the best proxies of `young' low-mass galaxies in the high-redshift Universe. One of the main goals of this study is to look for possible evidence of star formation (SF) activity induced by external perturbations. Recent results from HI mapping of a small subsample of XMD star-forming galaxies provided confident evidence for the important role of interaction-induced SF. Our observations provide complementary or new information that the great majority of the studied XMD dwarfs have strongly disturbed gas morphology and kinematics or the presence of detached components. We approximate the observed velocity fields by simple models of a rotating tilted thin disc, which allows us the robust detection of non-circular gas motions. These data, in turn, indicate the important role of current/recent interactions and mergers in the observed enhanced SF. As a by-product of our observations, we obtained data for two Low Surface Brightness (LSB) dwarf galaxies: Anon J012544+075957 that is a companion of the merger system UGC 993, and SAO 0822+3545 which shows off-centre, asymmetric, low star formation rate star-forming regions, likely induced by the interaction with the companion XMD dwarf HS 0822+3542. Based on observations obtained with the Special Astrophysical Observatory RAS 6-m telescope. E-mail: moisav@gmail.com (AVM); sap@sao.ru (SAP); akniazev@saao.ac.za (AYK)

  3. Gas-rich vs. gas-poor: LCID insights on the origin of different dwarf galaxy types

    NASA Astrophysics Data System (ADS)

    Gallart, C.; LCID Team

    In this paper, we discuss on the origin of different dwarf galaxy types, and the possible evolutionary links among them, based on full star formation histories (SFH) obtained through the Local Cosmology from Isolated Dwarfs (LCID) project. In the case of the dIrr and dT galaxies, these are the first time that full SFHs, describing the early episodes of star formation with fine time resolution (≃ 2 Gyr), have been obtained. The LCID results show that the early SFH of dIrr galaxies is fundamentally different from that of the studied dT and dSph, in that they haven't experienced a strong early burst, followed by a very mild or nil star formation activity. Instead, they started forming stars slowly and continued similarly over most of their lifetimes. Their SFH is similar to that of the (minority) dSph satellites of the Milky Way that have important amounts of intermediate-age population (namely, Carina, Fornax and Leo I). Based on the derived SFHs, we hypothesize that there are two fundamental types of dwarf galaxies: one type started their evolution vigorously forming stars, but their period of star formation activity has been short lived (few Gyr). Another type has had a mild star formation activity at early times, and has continued forming stars to the present time (or almost). The current availability of gas or lack thereof doesnÕt necessarily correlate with these two globally different evolutionary paths.

  4. K2-111 b - a short period super-Earth transiting a metal poor, evolved old star

    NASA Astrophysics Data System (ADS)

    Fridlund, Malcolm; Gaidos, Eric; Barragán, Oscar; Persson, Carina M.; Gandolfi, Davide; Cabrera, Juan; Hirano, Teruyuki; Kuzuhara, Masayuki; Csizmadia, Sz.; Nowak, Grzegorz; Endl, Michael; Grziwa, Sascha; Korth, Judith; Pfaff, Jeremias; Bitsch, Bertram; Johansen, Anders; Mustill, Alexander J.; Davies, Melvyn B.; Deeg, Hans J.; Palle, Enric; Cochran, William D.; Eigmüller, Philipp; Erikson, Anders; Guenther, Eike; Hatzes, Artie P.; Kiilerich, Amanda; Kudo, Tomoyuki; MacQueen, Phillip; Narita, Norio; Nespral, David; Pätzold, Martin; Prieto-Arranz, Jorge; Rauer, Heike; Van Eylen, Vincent

    2017-07-01

    Context. From a light curve acquired through the K2 space mission, the star K2-111(EPIC 210894022) has been identified as possibly orbited by a transiting planet. Aims: Our aim is to confirm the planetary nature of the object and derive its fundamental parameters. Methods: We analyse the light curve variations during the planetary transit using packages developed specifically for exoplanetary transits. Reconnaissance spectroscopy and radial velocity observations have been obtained using three separate telescope and spectrograph combinations. The spectroscopic synthesis package SME has been used to derive the stellar photospheric parameters that were used as input to various stellar evolutionary tracks in order to derive the parameters of the system. The planetary transit was also validated to occur on the assumed host star through adaptive imaging and statistical analysis. Results: The star is found to be located in the background of the Hyades cluster at a distance at least 4 times further away from Earth than the cluster itself. The spectrum and the space velocities of K2-111 strongly suggest it to be a member of the thick disk population. The co-added high-resolution spectra show that that it is a metal poor ([Fe/H] = - 0.53 ± 0.05 dex) and α-rich somewhat evolved solar-like star of spectral type G3. We find Teff = 5730 ± 50 K, log g⋆ = 4.15 ± 0.1 cgs, and derive a radius of R⋆ = 1.3 ± 0.1 R⊙ and a mass of M⋆ = 0.88 ± 0.02 M⊙. The currently available radial velocity data confirms a super-Earth class planet with a mass of 8.6 ± 3.9 M⊕ and a radius of 1.9 ± 0.2 R⊕. A second more massive object with a period longer than about 120 days is indicated by a long-term radial velocity drift. Conclusions: The radial velocity detection together with the imaging confirms with a high level of significance that the transit signature is caused by a planet orbiting the star K2-111. This planet is also confirmed in the radial velocity data. A second more

  5. Physical model of the vapor-liquid (insulator-metal) transition in an exciton gas

    SciTech Connect

    Khomkin, A. L. Shumikhin, A. S.

    2015-04-15

    We propose a simple physical model describing the transition of an exciton gas to a conducting exciton liquid. The transition occurs due to cohesive coupling of excitons in the vicinity of the critical point, which is associated with transformation of the exciton ground state to the conduction band and the emergence of conduction electrons. We calculate the cohesion binding energy for the exciton gas and, using it, derive the equations of state, critical parameters, and binodal. The computational method is analogous to that used by us earlier [5] for predicting the vapor-liquid (insulator-metal) phase transition in atomic (hypothetical, free of molecules) hydrogen and alkali metal vapors. The similarity of the methods used for hydrogen and excitons makes it possible to clarify the physical nature of the transition in the exciton gas and to predict more confidently the existence of a new phase transition in atomic hydrogen.

  6. ALFALFA Discovery of the Most Metal-poor Gas-rich Galaxy Known: AGC 198691

    NASA Astrophysics Data System (ADS)

    Hirschauer, Alec S.; Salzer, John J.; Skillman, Evan D.; Berg, Danielle; McQuinn, Kristen B. W.; Cannon, John M.; Gordon, Alex J. R.; Haynes, Martha P.; Giovanelli, Riccardo; Adams, Elizabeth A. K.; Janowiecki, Steven; Rhode, Katherine L.; Pogge, Richard W.; Croxall, Kevin V.; Aver, Erik

    2016-05-01

    We present spectroscopic observations of the nearby dwarf galaxy AGC 198691. This object is part of the Survey of H i in Extremely Low-Mass Dwarfs project, which is a multi-wavelength study of galaxies with H i masses in the range of 106-107.2 M ⊙, discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We have obtained spectra of the lone H ii region in AGC 198691 with the new high-throughput KPNO Ohio State Multi-Object Spectrograph on the Mayall 4 m, as well as with the Blue Channel spectrograph on the MMT 6.5 m telescope. These observations enable the measurement of the temperature-sensitive [O iii]λ4363 line and hence the determination of a “direct” oxygen abundance for AGC 198691. We find this system to be an extremely metal-deficient (XMD) system with an oxygen abundance of 12+log(O/H) = 7.02 ± 0.03, making AGC 198691 the lowest-abundance star-forming galaxy known in the local universe. Two of the five lowest-abundance galaxies known have been discovered by the ALFALFA blind H i survey; this high yield of XMD galaxies represents a paradigm shift in the search for extremely metal-poor galaxies.

  7. Evaluation of aerated biofilter systems for microbial methane oxidation of poor landfill gas.

    PubMed

    Haubrichs, R; Widmann, R

    2006-01-01

    In the long-term, landfills are producing landfill gas (LFG) with low calorific values. Therefore, the utilization of LFG in combined heat and power plants (CHP) is limited to a certain period of time. A feasible method for LFG treatment is microbial CH(4) oxidation. Different materials were tested in actively aerated lab-scale bio-filter systems with a volume of 0.167 m(3). The required oxygen for the microbial CH(4) oxidation was provided through perforated probes, which distributed ambient air into the filter material. Three air input levels were installed along the height of the filter, each of them adjusted to a particular flow rate. During the tests, stable degradation rates of around 28 g/(m(3) h) in a fine-grained compost material were observed at a CH(4) inlet concentration of 30% over a period of 148 days. Compared with passive (not aerated) tests, the CH(4) oxidation rate increased by a factor of 5.5. Therefore, the enhancement of active aeration on the microbial CH(4) oxidation was confirmed. At a O(2)/CH(4) ratio of 2.5, nearly 100% of the CH(4) load was decomposed. By lowering the ratio from 2.5 to 2, the efficiency fell to values from 88% to 92%. By varying the distribution to the three air input levels, the CH(4) oxidation process was spread more evenly over the filter volume.

  8. Discontinuous phase transition in a dimer lattice gas

    NASA Astrophysics Data System (ADS)

    Dickman, Ronald

    2012-05-01

    I study a dimer model on the square lattice with nearest neighbor exclusion as the only interaction. Detailed simulations using tomographic entropic sampling show that as the chemical potential is varied, there is a strongly discontinuous phase transition, at which the particle density jumps by about 18% of its maximum value, 1/4. The transition is accompanied by the onset of orientational order, to an arrangement corresponding to the {1/2, 0, 1/2} structure identified by Phares et al. [Physica B 409, 1096 (2011)] in a dimer model with finite repulsion at fixed density. Using finite-size scaling and Binder's cumulant, the expected scaling behavior at a discontinuous transition is verified in detail. The discontinuous transition can be understood qualitatively given that the model possesses eight equivalent maximum-density configurations, so that its coarse-grained description corresponds to that of the q = 8 Potts model.

  9. Discontinuous phase transition in a dimer lattice gas.

    PubMed

    Dickman, Ronald

    2012-05-07

    I study a dimer model on the square lattice with nearest neighbor exclusion as the only interaction. Detailed simulations using tomographic entropic sampling show that as the chemical potential is varied, there is a strongly discontinuous phase transition, at which the particle density jumps by about 18% of its maximum value, 1/4. The transition is accompanied by the onset of orientational order, to an arrangement corresponding to the {1/2, 0, 1/2} structure identified by Phares et al. [Physica B 409, 1096 (2011)] in a dimer model with finite repulsion at fixed density. Using finite-size scaling and Binder's cumulant, the expected scaling behavior at a discontinuous transition is verified in detail. The discontinuous transition can be understood qualitatively given that the model possesses eight equivalent maximum-density configurations, so that its coarse-grained description corresponds to that of the q = 8 Potts model.

  10. A pressure-amplifying framework material with negative gas adsorption transitions.

    PubMed

    Krause, Simon; Bon, Volodymyr; Senkovska, Irena; Stoeck, Ulrich; Wallacher, Dirk; Többens, Daniel M; Zander, Stefan; Pillai, Renjith S; Maurin, Guillaume; Coudert, François-Xavier; Kaskel, Stefan

    2016-04-21

    Adsorption-based phenomena are important in gas separations, such as the treatment of greenhouse-gas and toxic-gas pollutants, and in water-adsorption-based heat pumps for solar cooling systems. The ability to tune the pore size, shape and functionality of crystalline porous coordination polymers--or metal-organic frameworks (MOFs)--has made them attractive materials for such adsorption-based applications. The flexibility and guest-molecule-dependent response of MOFs give rise to unexpected and often desirable adsorption phenomena. Common to all isothermal gas adsorption phenomena, however, is increased gas uptake with increased pressure. Here we report adsorption transitions in the isotherms of a MOF (DUT-49) that exhibits a negative gas adsorption; that is, spontaneous desorption of gas (methane and n-butane) occurs during pressure increase in a defined temperature and pressure range. A combination of in situ powder X-ray diffraction, gas adsorption experiments and simulations shows that this adsorption behaviour is controlled by a sudden hysteretic structural deformation and pore contraction of the MOF, which releases guest molecules. These findings may enable technologies using frameworks capable of negative gas adsorption for pressure amplification in micro- and macroscopic system engineering. Negative gas adsorption extends the series of counterintuitive phenomena such as negative thermal expansion and negative refractive indices and may be interpreted as an adsorptive analogue of force-amplifying negative compressibility transitions proposed for metamaterials.

  11. A pressure-amplifying framework material with negative gas adsorption transitions

    NASA Astrophysics Data System (ADS)

    Krause, Simon; Bon, Volodymyr; Senkovska, Irena; Stoeck, Ulrich; Wallacher, Dirk; Többens, Daniel M.; Zander, Stefan; Pillai, Renjith S.; Maurin, Guillaume; Coudert, François-Xavier; Kaskel, Stefan

    2016-04-01

    Adsorption-based phenomena are important in gas separations, such as the treatment of greenhouse-gas and toxic-gas pollutants, and in water-adsorption-based heat pumps for solar cooling systems. The ability to tune the pore size, shape and functionality of crystalline porous coordination polymers—or metal-organic frameworks (MOFs)—has made them attractive materials for such adsorption-based applications. The flexibility and guest-molecule-dependent response of MOFs give rise to unexpected and often desirable adsorption phenomena. Common to all isothermal gas adsorption phenomena, however, is increased gas uptake with increased pressure. Here we report adsorption transitions in the isotherms of a MOF (DUT-49) that exhibits a negative gas adsorption; that is, spontaneous desorption of gas (methane and n-butane) occurs during pressure increase in a defined temperature and pressure range. A combination of in situ powder X-ray diffraction, gas adsorption experiments and simulations shows that this adsorption behaviour is controlled by a sudden hysteretic structural deformation and pore contraction of the MOF, which releases guest molecules. These findings may enable technologies using frameworks capable of negative gas adsorption for pressure amplification in micro- and macroscopic system engineering. Negative gas adsorption extends the series of counterintuitive phenomena such as negative thermal expansion and negative refractive indices and may be interpreted as an adsorptive analogue of force-amplifying negative compressibility transitions proposed for metamaterials.

  12. 33 CFR 165.1709 - Security Zones: Liquefied Natural Gas Tanker Transits and Operations at Phillips Petroleum LNG...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Gas Tanker Transits and Operations at Phillips Petroleum LNG Pier, Cook Inlet, AK. 165.1709 Section...: Liquefied Natural Gas Tanker Transits and Operations at Phillips Petroleum LNG Pier, Cook Inlet, AK. (a... and outbound transits through Cook Inlet, Alaska between the Phillips Petroleum LNG Pier, 60°40′43″...

  13. 33 CFR 165.1709 - Security Zones: Liquefied Natural Gas Tanker Transits and Operations at Phillips Petroleum LNG...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Gas Tanker Transits and Operations at Phillips Petroleum LNG Pier, Cook Inlet, AK. 165.1709 Section...: Liquefied Natural Gas Tanker Transits and Operations at Phillips Petroleum LNG Pier, Cook Inlet, AK. (a... and outbound transits through Cook Inlet, Alaska between the Phillips Petroleum LNG Pier, 60°40′43″...

  14. 33 CFR 165.1709 - Security Zones: Liquefied Natural Gas Tanker Transits and Operations at Phillips Petroleum LNG...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Gas Tanker Transits and Operations at Phillips Petroleum LNG Pier, Cook Inlet, AK. 165.1709 Section...: Liquefied Natural Gas Tanker Transits and Operations at Phillips Petroleum LNG Pier, Cook Inlet, AK. (a... and outbound transits through Cook Inlet, Alaska between the Phillips Petroleum LNG Pier, 60°40′43″...

  15. 33 CFR 165.1709 - Security Zones: Liquefied Natural Gas Tanker Transits and Operations at Phillips Petroleum LNG...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Gas Tanker Transits and Operations at Phillips Petroleum LNG Pier, Cook Inlet, AK. 165.1709 Section...: Liquefied Natural Gas Tanker Transits and Operations at Phillips Petroleum LNG Pier, Cook Inlet, AK. (a... and outbound transits through Cook Inlet, Alaska between the Phillips Petroleum LNG Pier, 60°40′43″...

  16. CO2 Capture from Flue Gas by Phase Transitional Absorption

    SciTech Connect

    Liang Hu

    2009-06-30

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

  17. 33 CFR 165.1709 - Security Zones: Liquefied Natural Gas Tanker Transits and Operations at Phillips Petroleum LNG...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Gas Tanker Transits and Operations at Phillips Petroleum LNG Pier, Cook Inlet, AK. 165.1709 Section...: Liquefied Natural Gas Tanker Transits and Operations at Phillips Petroleum LNG Pier, Cook Inlet, AK. (a... navigable waters within a 1000-yard radius of the Liquefied Natural Gas (LNG) tankers during their...

  18. Resonance transition 795-nm Rubidium laser using 3He buffer gas

    SciTech Connect

    Wu, S S; Soules, T F; Page, R H; Mitchell, S C; Kanz, V K; Beach, R J

    2007-08-02

    We report the first demonstration of a 795-nm Rubidium resonance transition laser using a buffer gas consisting of pure {sup 3}He. This follows our recent demonstration of a hydrocarbon-free 795-nm Rubidium resonance laser which used naturally-occurring He as the buffer gas. Using He gas that is isotopically enriched with {sup 3}He yields enhanced mixing of the Rb fine-structure levels. This enables efficient lasing at reduced He buffer gas pressure, improving thermal management in high average power Rb lasers and enhancing the power scaling potential of such systems.

  19. Rac1 overexpression is correlated with epithelial mesenchymal transition and predicts poor prognosis in non-small cell lung cancer

    PubMed Central

    Zhou, Yujuan; Liao, Qianjin; Han, Yaqian; Chen, Jie; Liu, Zhigang; Ling, Hang; Zhang, Jing; Yang, Wenjuan; Oyang, Linda; Xia, Longzheng; Wang, Li; Wang, Heran; Xue, Lei; Wang, Hui; Hu, Bingqiang

    2016-01-01

    Objective: Ras-related C3 botulinum toxin substrate1(Rac1) and epithelial mesenchymal transition (EMT) are key therapeutic targets in cancer. We investigated the clinical significance of Rac1 and markers of EMT expression in non-small cell lung cancer (NSCLC), and their possible correlation with EMT phenotype. Methods: Immunohistochemistry was used to assess the expression of Rac1, Snail1, Twist1, N-cadherin (N-cad), Vimentin (Vim), and E-cadherin (E-cad) in 153 NSCLC paraffin-embedded specimens and 45 normal specimens adjacent to tumors. The correlation of Rac1 and EMT markers with clinicopathological characteristics and the relationship between the protein levels and progression-free survival (PFS) and overall survival (OS) were analyzed. Results: Compared with non-tumor tissues, the NSCLC tissues showed marked elevation in the levels of Rac1, Snail1, Twist1, N-cad, and Vim levels, whereas the E-cad levels were significantly decreased (P < 0.05). The aberrant expression of Rac1 and EMT markers was significantly associated with TNM stage and metastasis (P < 0.05). Increased expression of Rac1 may be associated with poor OS and PFS compared with low expression (P<0.001 and P=0.004). Significant correlations were observed between the EMT markers expressed and OS or PFS(P<0.01). In addition, multivariate analysis indicated that the expression of Rac1, Snail1, Twist1, N-cad, Vim, and E-cad was an independent prognostic factor in NSCLC. Interestingly, Rac1 expression was positively correlated with Snail1, Twist1, N-cad, and Vim levels (r=0.563, r=0.440, r=0.247 r=0.536, P<0.01, respectively) and negatively correlated with E-cad levels (r=-0.464, P<0.001) in NSCLC tissues. Rac1, Twist, Snail1, Vim and N-cad were highly expressed in lung cancer patients resistant to radiotherapy, while E-cad was poorly expressed. Conclusion: Rac1 may promote NSCLC progression and metastasis via EMT, which may be considered as a potential therapeutic target. PMID:27877226

  20. Transition from weak wave turbulence to soliton gas

    NASA Astrophysics Data System (ADS)

    Hassaini, Roumaissa; Mordant, Nicolas

    2017-09-01

    We report an experimental investigation of the effect of finite depth on the statistical properties of wave turbulence at the surface of water in the gravity-capillary range. We tune the wave dispersion and the level of nonlinearity by modifying the depth of water and the forcing, respectively. We use space-time resolved profilometry to reconstruct the deformed surface of water. When decreasing the water depth, we observe a drastic transition between weak turbulence at the weakest forcing and a solitonic regime at stronger forcing. We characterize the transition between both states by studying their Fourier spectra. We also study the efficiency of energy transfer in the weak turbulence regime. We report a loss of efficiency of angular transfer as the dispersion of the wave is reduced until the system bifurcates into the solitonic regime.

  1. Phase transitions during compression and decompression of clots from platelet-poor plasma, platelet-rich plasma and whole blood.

    PubMed

    Liang, Xiaojun; Chernysh, Irina; Purohit, Prashant K; Weisel, John W

    2017-09-15

    Blood clots are required to stem bleeding and are subject to a variety of stresses, but they can also block blood vessels and cause heart attacks and ischemic strokes. We measured the compressive response of human platelet-poor plasma (PPP) clots, platelet-rich plasma (PRP) clots and whole blood clots and correlated these measurements with confocal and scanning electron microscopy to track changes in clot structure. Stress-strain curves revealed four characteristic regions, for compression-decompression: (1) linear elastic region; (2) upper plateau or softening region; (3) non-linear elastic region or re-stretching of the network; (4) lower plateau in which dissociation of some newly made connections occurs. Our experiments revealed that compression proceeds by the passage of a phase boundary through the clot separating rarefied and densified phases. This observation motivates a model of fibrin mechanics based on the continuum theory of phase transitions, which accounts for the pre-stress caused by platelets, the adhesion of fibrin fibers in the densified phase, the compression of red blood cells (RBCs), and the pumping of liquids through the clot during compression/decompression. Our experiments and theory provide insights into the mechanical behavior of blood clots that could have implications clinically and in the design of fibrin-based biomaterials. The objective of this paper is to measure and mathematically model the compression behavior of various human blood clots. We show by a combination of confocal and scanning electron microscopy that compression proceeds by the passage of a front through the sample that separates a densified region of the clot from a rarefied region, and that the compression/decompression response is reversible with hysteresis. These observations form the basis of a model for the compression response of clots based on the continuum theory of phase transitions. Our studies may reveal how clot rheology under large compression in vivo due

  2. Nonequilibrium Features of the Nuclear Liquid-Gas Phase Transition

    NASA Astrophysics Data System (ADS)

    Zwieglinski, B.; Odeh, T.; Gross, C.; Schwarz, C.; Bassini, R.; Begemann-Blaich, M.; Blaich, T.; Emling, H.; Ferrero, A.; Fritz, S.; Gaff, S. J.; Imme, G.; Iori, I.; Kleinevoss, U.; Kunde, G. J.; Kunze, W. D.; Lindenstruth, V.; Lynen, U.; Mahi, M.; Moroni, A.; Moehlenkamp, T.; Mueller, W. F. J.; Ocker, B.; Pochodzalla, J.; Raciti, G.; Rubehn, Th.; Sann, H.; Schnittker, M.; Schuettauf, A.; Seidel, W.; Serfling, V.; Stroth, J.; Trautmann, W.; Trzcinski, A.; Verde, G.; Woerner, A.; Xi, H.; Zude, E.

    1999-03-01

    Energy spectra of protons emitted by the target residue in Au + Au collisions at 1 GeV/u were measured for different excitation energy bins. They reveal two components with different slopes attributed to preequilibrium and equilibrium emission. The relative contribution of the latter decreases rapidly with excitation energy, so that its presence becomes not apparent for the highest energy bins. It is argued therefore, that equilibrium may not be reached on the gas branch of the caloric curve.

  3. h-Prune is associated with poor prognosis and epithelial-mesenchymal transition in patients with colorectal liver metastases.

    PubMed

    Hashimoto, Masakazu; Kobayashi, Tsuyoshi; Tashiro, Hirotaka; Arihiro, Koji; Kikuchi, Akira; Ohdan, Hideki

    2016-08-15

    The prognosis of patients with colorectal liver metastases (CRLM) remains low despite advances in chemotherapy and surgery. The expression of h-prune (human homolog of Drosophila prune protein; HGNC13420), an exopolyphosphatase, is correlated with progression and aggressiveness in several cancers and promotes migration and invasion. We investigated the role of h-prune in CRLM. To investigate the role of h-prune, immunohistochemical analysis for h-prune was performed in 87 surgically resected specimens of CRLM obtained between 2001 and 2009 at the Hiroshima University Hospital. Immunohistochemical analysis revealed positive staining for h-prune in 24 (28%) cases. The overall survival rate was significantly lower in h-prune-positive cases than in h-prune-negative cases (p = 0.003). Multivariate analysis showed that h-prune positivity was the only independent factor related to poor overall survival of patients after curative hepatectomy of CRLM. In vitro and in vivo, h-prune-knocked-down and h-prune-overexpressing cells were analyzed. In vitro, h-prune was associated with increased cell motility and upregulation of epithelial-mesenchymal transition (EMT) markers. In a mouse model, h-prune was associated with invasion of the tumor and distant metastases. In summary, h-prune expression is a useful marker to identify high-risk patients for resectable colorectal liver metastasis. h-Prune expression is necessary for cancer cell motility and EMT and is associated with liver and lung metastasis in colorectal cancer cells. h-Prune could be a new prognostic marker and molecular target for CRLM. © 2016 UICC.

  4. Toward the renewables - A natural gas/solar energy transition strategy

    NASA Technical Reports Server (NTRS)

    Hanson, J. A.; Escher, W. J. D.

    1979-01-01

    The inevitability of an energy transition from today's non-renewable fossil base toward a renewable energy base is considered from the viewpoint of the need for a national transition strategy. Then, one such strategy is offered. Its technological building blocks are described in terms of both energy use and energy supply. The strategy itself is then sketched at four points in its implementation; (1) initiation, (2) early transition, (3) late transition, and (4) completion. The transition is assumed to evolve from a heavily natural gas-dependent energy economy. It then proceeds through its transition toward a balanced, hybrid energy system consisting of both centralized and dispersed energy supply technologies supplying hydrogen and electricity from solar energy. Related institutional, environmental and economic factors are examined briefly.

  5. Toward the renewables - A natural gas/solar energy transition strategy

    NASA Technical Reports Server (NTRS)

    Hanson, J. A.; Escher, W. J. D.

    1979-01-01

    The inevitability of an energy transition from today's non-renewable fossil base toward a renewable energy base is considered from the viewpoint of the need for a national transition strategy. Then, one such strategy is offered. Its technological building blocks are described in terms of both energy use and energy supply. The strategy itself is then sketched at four points in its implementation; (1) initiation, (2) early transition, (3) late transition, and (4) completion. The transition is assumed to evolve from a heavily natural gas-dependent energy economy. It then proceeds through its transition toward a balanced, hybrid energy system consisting of both centralized and dispersed energy supply technologies supplying hydrogen and electricity from solar energy. Related institutional, environmental and economic factors are examined briefly.

  6. Scaling properties of the plateau transitions in the two-dimensional hole gas system

    NASA Astrophysics Data System (ADS)

    Wang, Xuebin; Liu, Haiwen; Zhu, Junbo; Shan, Pujia; Wang, Pengjie; Fu, Hailong; Du, Lingjie; Pfeiffer, L. N.; West, K. W.; Xie, X. C.; Du, Rui-Rui; Lin, Xi

    2016-02-01

    The behavior of phase coherence is studied in two-dimensional hole gas through the integer quantum Hall plateau-to-plateau transition. From the plateau transition as a function of temperature, scaling properties of multiple transitions are analyzed. Our results are in good agreement with the assumption of the zero-point fluctuations of the coherent holes, and support the intrinsic saturation of the coherence time at low temperature limit. The critical exponent p can also be determined under the scheme of the zero-point fluctuations. The similarity and difference in experimental observations between quantum Griffiths singularity and plateau transition is discussed. The spin-orbit coupling effect's influence on the plateau transition is explored by comparing the results from different transitions.

  7. Evaluating transition-metal catalysis in gas generation from the Permian Kupferschiefer by hydrous pyrolysis

    NASA Astrophysics Data System (ADS)

    Lewan, M. D.; Kotarba, M. J.; Więcław, D.; Piestrzyński, A.

    2008-08-01

    Transition metals in source rocks have been advocated as catalysts in determining extent, composition, and timing of natural gas generation (Mango, F. D. (1996) Transition metal catalysis in the generation of natural gas. Org. Geochem.24, 977-984). This controversial hypothesis may have important implications concerning gas generation in unconventional shale-gas accumulations. Although experiments have been conducted to test the metal-catalysis hypothesis, their approach and results remain equivocal in evaluating natural assemblages of transition metals and organic matter in shale. The Permian Kupferschiefer of Poland offers an excellent opportunity to test the hypothesis with immature to marginally mature shale rich in both transition metals and organic matter. Twelve subsurface samples containing similar Type-II kerogen with different amounts and types of transition metals were subjected to hydrous pyrolysis at 330° and 355 °C for 72 h. The gases generated in these experiments were quantitatively collected and analyzed for molecular composition and stable isotopes. Expelled immiscible oils, reacted waters, and spent rock were also quantitatively collected. The results show that transition metals have no effect on methane yields or enrichment. δ 13C values of generated methane, ethane, propane and butanes show no systematic changes with increasing transition metals. The potential for transition metals to enhance gas generation and oil cracking was examined by looking at the ratio of the generated hydrocarbon gases to generated expelled immiscible oil (i.e., GOR), which showed no systematic change with increasing transition metals. Assuming maximum yields at 355 °C for 72 h and first-order reaction rates, pseudo-rate constants for methane generation at 330 °C were calculated. These rate constants showed no increase with increasing transition metals. The lack of a significant catalytic effect of transition metals on the extent, composition, and timing of

  8. Evaluating transition-metal catalysis in gas generation from the Permian Kupferschiefer by hydrous pyrolysis

    USGS Publications Warehouse

    Lewan, M.D.; Kotarba, M.J.; Wieclaw, D.; Piestrzynski, A.

    2008-01-01

    Transition metals in source rocks have been advocated as catalysts in determining extent, composition, and timing of natural gas generation (Mango, F. D. (1996) Transition metal catalysis in the generation of natural gas. Org. Geochem.24, 977–984). This controversial hypothesis may have important implications concerning gas generation in unconventional shale-gas accumulations. Although experiments have been conducted to test the metal-catalysis hypothesis, their approach and results remain equivocal in evaluating natural assemblages of transition metals and organic matter in shale. The Permian Kupferschiefer of Poland offers an excellent opportunity to test the hypothesis with immature to marginally mature shale rich in both transition metals and organic matter. Twelve subsurface samples containing similar Type-II kerogen with different amounts and types of transition metals were subjected to hydrous pyrolysis at 330° and 355 °C for 72 h. The gases generated in these experiments were quantitatively collected and analyzed for molecular composition and stable isotopes. Expelled immiscible oils, reacted waters, and spent rock were also quantitatively collected. The results show that transition metals have no effect on methane yields or enrichment. δ13C values of generated methane, ethane, propane and butanes show no systematic changes with increasing transition metals. The potential for transition metals to enhance gas generation and oil cracking was examined by looking at the ratio of the generated hydrocarbon gases to generated expelled immiscible oil (i.e., GOR), which showed no systematic change with increasing transition metals. Assuming maximum yields at 355 °C for 72 h and first-order reaction rates, pseudo-rate constants for methane generation at 330 °C were calculated. These rate constants showed no increase with increasing transition metals. The lack of a significant catalytic effect of transition metals on the extent, composition, and timing of

  9. Finite-time thermodynamics and the gas-liquid phase transition

    NASA Astrophysics Data System (ADS)

    Santoro, M.; Schön, J. C.; Jansen, M.

    2007-12-01

    In this paper, we study the application of the concept of finite-time thermodynamics to first-order phase transitions. As an example, we investigate the transition from the gaseous to the liquid state by modeling the liquification of the gas in a finite time. In particular, we introduce, state, and solve an optimal control problem in which we aim at achieving the gas-liquid first-order phase transition through supersaturation within a fixed time in an optimal fashion, in the sense that the work required to supersaturate the gas, called excess work, is minimized by controlling the appropriate thermodynamic parameters. The resulting set of coupled nonlinear differential equations is then solved for three systems, nitrogen N2 , oxygen O2 , and water vapor H2O .

  10. Dynamic transition of supercritical hydrogen: defining the boundary between interior and atmosphere in gas giants.

    PubMed

    Trachenko, K; Brazhkin, V V; Bolmatov, D

    2014-03-01

    Understanding the physics of gas giants requires knowledge about the behavior of hydrogen at extreme pressures and temperatures. Molecular hydrogen in these planets is supercritical, and has been considered as a physically homogeneous state where no differences can be made between a liquid and a gas and where all properties undergo no marked or distinct changes with pressure and temperature, the picture believed to hold below the dissociation and metallization transition. Here, we show that in Jupiter and Saturn, supercritical molecular hydrogen undergoes a dynamic transition around 10 GPa and 3000 K from the "rigid" liquid state to the "nonrigid" gas-like fluid state at the Frenkel line recently proposed, with the accompanying qualitative changes of all major physical properties. The consequences of this finding are discussed, including a physically justified way to demarcate the interior and the atmosphere in gas giants.

  11. Third interim report on status of gas turbine transit bus demonstration program

    SciTech Connect

    1980-04-15

    Progress in a program for demonstrating the use of gas turbines in city buses is reported. Five prototype gas turbine engines, Model GT-40404, manufactured by the Detroit Diesel Allison Division of General Motors Corporation, are being integrated into five RTS-II model transit coaches, manufactured by General Motors Corporation and supplied by the Mass Transit Administration (MTA) of Baltimore, Maryland. They will be acceptance tested at the Transportation Research Center proving grounds in Ohio, where one gas turbine coach will also be performance and mileage tested against a diesel RTS-II coach. The first diesel-to-turbine engine conversion is done. The second conversion is almost completed. The demonstration plan for the 5 gas turbine coaches has been finalized. (LCL)

  12. THE TRANSIT TRANSMISSION SPECTRUM OF A COLD GAS GIANT PLANET

    SciTech Connect

    Dalba, Paul A.; Muirhead, Philip S.; Veyette, Mark J.; Fortney, Jonathan J.; Hedman, Matthew M.; Nicholson, Philip D.

    2015-12-01

    We use solar occultations observed by the Visual and Infrared Mapping Spectrometer on board the Cassini Spacecraft to extract the 1–5 μm transmission spectrum of Saturn, as if it were a transiting exoplanet. We detect absorption from methane, ethane, acetylene, aliphatic hydrocarbons, and possibly carbon monoxide, with peak-to-peak features of up to 90 parts-per-million despite the presence of ammonia clouds. We also find that atmospheric refraction, as opposed to clouds or haze, determines the minimum altitude that could be probed during mid-transit. Self-consistent exoplanet atmosphere models show good agreement with Saturn’s transmission spectrum but fail to reproduce a large absorption feature near 3.4 μm, likely caused by gaseous ethane and a C–H stretching mode of an unknown aliphatic hydrocarbon. This large feature is located in one of the Spitzer Space Telescope bandpasses and could alter interpretations of transmission spectra if not properly modeled. The large signal in Saturn’s transmission spectrum suggests that transmission spectroscopy of cold, long-period gaseous exoplanets should be possible with current and future observatories. Motivated by these results, we briefly consider the feasibility of  using a survey to search for and characterize cold exoplanets that are analogous to Jupiter and Saturn utilizing a target-of-opportunity approach.

  13. Determination of the Ductile to Brittle Transition Temperature of Platinum-Aluminide Gas Turbine Blade Coatings

    DTIC Science & Technology

    1985-09-01

    to brittle transition temperature (DBTT) of five basic platinum- aluminide gas turbine blade coatings on a nickel-base superalloy (IN738). The results...gas turbine blade coatings on a nickel-base superalloy (IN738). The results of these tests were compared to similarly formed nickel- aluminide coatings ... aluminide coating became more widely used, it -°j.established itself as an excellent life extender for most superalloy blade materials. However, as

  14. Tradeoffs between costs and greenhouse gas emissions in the design of urban transit systems

    NASA Astrophysics Data System (ADS)

    Griswold, Julia B.; Madanat, Samer; Horvath, Arpad

    2013-12-01

    Recent investments in the transit sector to address greenhouse gas emissions have concentrated on purchasing efficient replacement vehicles and inducing mode shift from the private automobile. There has been little focus on the potential of network and operational improvements, such as changes in headways, route spacing, and stop spacing, to reduce transit emissions. Most models of transit system design consider user and agency cost while ignoring emissions and the potential environmental benefit of operational improvements. We use a model to evaluate the user and agency costs as well as greenhouse gas benefit of design and operational improvements to transit systems. We examine how the operational characteristics of urban transit systems affect both costs and greenhouse gas emissions. The research identifies the Pareto frontier for designing an idealized transit network. Modes considered include bus, bus rapid transit (BRT), light rail transit (LRT), and metro (heavy) rail, with cost and emissions parameters appropriate for the United States. Passenger demand follows a many-to-many travel pattern with uniformly distributed origins and destinations. The approaches described could be used to optimize the network design of existing bus service or help to select a mode and design attributes for a new transit system. The results show that BRT provides the lowest cost but not the lowest emissions for our large city scenarios. Bus and LRT systems have low costs and the lowest emissions for our small city scenarios. Relatively large reductions in emissions from the cost-optimal system can be achieved with only minor increases in user travel time.

  15. Transition and Damping of Collective Modes in a Trapped Fermi Gas between BCS and Unitary Limits near the Phase Transition

    PubMed Central

    Dong, Hang; Zhang, Wenyuan; Zhou, Li; Ma, Yongli

    2015-01-01

    We investigate the transition and damping of low-energy collective modes in a trapped unitary Fermi gas by solving the Boltzmann-Vlasov kinetic equation in a scaled form, which is combined with both the T-matrix fluctuation theory in normal phase and the mean-field theory in order phase. In order to connect the microscopic and kinetic descriptions of many-body Feshbach scattering, we adopt a phenomenological two-fluid physical approach, and derive the coupling constants in the order phase. By solving the Boltzmann-Vlasov steady-state equation in a variational form, we calculate two viscous relaxation rates with the collision probabilities of fermion’s scattering including fermions in the normal fluid and fermion pairs in the superfluid. Additionally, by considering the pairing and depairing of fermions, we get results of the frequency and damping of collective modes versus temperature and s-wave scattering length. Our theoretical results are in a remarkable agreement with the experimental data, particularly for the sharp transition between collisionless and hydrodynamic behaviour and strong damping between BCS and unitary limits near the phase transition. The sharp transition originates from the maximum of viscous relaxation rate caused by fermion-fermion pair collision at the phase transition point when the fermion depair, while the strong damping due to the fast varying of the frequency of collective modes from BCS limit to unitary limit. PMID:26522094

  16. B2 1637+29, a massive radio galaxy probing a poor but gas-rich group

    SciTech Connect

    De Ruiter, H.R.; Parma, P.; Fanti, R.; Ekers, R.D.

    1988-06-01

    New VLA and CCD observations of the radio source B2 1637+29, a member of the faint B2 sample of low-luminosity radio galaxies, are reported. The environment of the galaxy is discussed, and a description of the radio source morphology is given. The CCD image reveals that the optical counterpart is a double galaxy with radio jets emanating from the nucleus of the brighter of the two galaxies. It is shown that the galaxy is the dominant member of a poor group of galaxies, and it is argued that it moves with an average velocity of a few hundred km/s with respect to an intergalactic gas cloud with mass of 10 to the 13th solar or more. The relevance of the enviroment of the radio galaxy to the source morphology is discussed, and an explanation for the highly peculiar features, such as the undulation in the radio tail and the difference in both length and brightness of the main and counter jet, is proposed. 32 references.

  17. Swirling midframe flow for gas turbine engine having advanced transitions

    DOEpatents

    Montgomery, Matthew D.; Charron, Richard C.; Rodriguez, Jose L.; Kusters, Bernhard W.; Morrison, Jay A.; Beeck, Alexander R.

    2016-12-27

    A gas turbine engine can-annular combustion arrangement (10), including: an axial compressor (82) operable to rotate in a rotation direction (60); a diffuser (100, 110) configured to receive compressed air (16) from the axial compressor; a plenum (22) configured to receive the compressed air from the diffuser; a plurality of combustor cans (12) each having a combustor inlet (38) in fluid communication with the plenum, wherein each combustor can is tangentially oriented so that a respective combustor inlet is circumferentially offset from a respective combustor outlet in a direction opposite the rotation direction; and an airflow guiding arrangement (80) configured to impart circumferential motion to the compressed air in the plenum in the direction opposite the rotation direction.

  18. Coherence properties of a two-dimensional trapped Bose gas around the superfluid transition

    SciTech Connect

    Plisson, T.; Allard, B.; Salomon, G.; Aspect, A.; Bourdel, T.; Holzmann, M.; Bouyer, P.

    2011-12-15

    We measure the momentum distribution of a two-dimensional trapped Bose gas and observe the increase of the range of coherence around the Berezinskii-Kosterlitz-Thouless (BKT) transition. We quantitatively compare our observed profiles to both a Hartree-Fock mean-field theory and quantum Monte Carlo simulations. In the normal phase, the momentum distribution is observed to sharpen well before the phase transition. This behavior is partially captured in a mean-field approach, in contrast to the physics of the BKT transition.

  19. Influence of the coulomb interaction on the liquid-gas phase transition and nuclear multifragmentation.

    PubMed

    Gulminelli, F; Chomaz, Ph; Raduta, Al H; Raduta, Ad R

    2003-11-14

    The liquid-gas phase transition is analyzed from the topologic properties of the event distribution in the observables space. A multicanonical formalism allows one to directly relate the standard phase transition with neutral particles to the case where the nonsaturating Coulomb interaction is present, and to interpret the Coulomb effect as a deformation of the probability distributions and a rotation of the order parameter. This formalism is applied to a statistical multifragmentation model and consequences for the nuclear multifragmentation phase transitions are drawn.

  20. An optical transmission spectrum of the transiting hot Jupiter in the metal-poor WASP-98 planetary system

    NASA Astrophysics Data System (ADS)

    Mancini, L.; Giordano, M.; Mollière, P.; Southworth, J.; Brahm, R.; Ciceri, S.; Henning, Th.

    2016-09-01

    The WASP-98 planetary system represents a rare case of a hot Jupiter hosted by a metal-poor main-sequence star. We present a follow-up study of this system based on multiband photometry and high-resolution spectroscopy. Two new transit events of WASP-98 b were simultaneously observed in four passbands (g', r', i', z'), using the telescope-defocusing technique, yielding eight high-precision light curves with point-to-point scatters of less than 1 mmag. We also collected three spectra of the parent star with a high-resolution spectrograph, which we used to remeasure its spectral characteristics, in particular its metallicity. We found this to be very low, [Fe/H] = -0.49 ± 0.10, but larger than was previously reported, [Fe/H] = -0.60 ± 0.19. We used these new photometric and spectroscopic data to refine the orbital and physical properties of this planetary system, finding that the stellar and planetary mass measurements are significantly larger than those in the discovery paper. In addition, the multiband light curves were used to construct an optical transmission spectrum of WASP-98 b and probe the characteristics of its atmosphere at the terminator. We measured a lower radius at z' compared with the other three passbands. The maximum variation is between the r' and z' bands, has a confidence level of roughly 6σ and equates to 5.5 pressure scale heights. We compared this spectrum to theoretical models, investigating several possible types of atmospheres, including hazy, cloudy, cloud-free, and clear atmospheres with titanium and vanadium oxide opacities. We could not find a good fit to the observations, except in the extreme case of a clear atmosphere with TiO and VO opacities, in which the condensation of Ti and V was suppressed. As this case is unrealistic, our results suggest the presence of an additional optical-absorbing species in the atmosphere of WASP-98 b, of unknown chemical nature.

  1. Herschel evidence for disk flattening or gas depletion in transitional disks

    SciTech Connect

    Keane, J. T.; Pascucci, I.; Espaillat, C.; Woitke, P.; Andrews, S.; Kamp, I.; Thi, W.-F.; Meeus, G.; Dent, W. R. F.

    2014-06-01

    Transitional disks are protoplanetary disks characterized by reduced near- and mid-infrared emission, with respect to full disks. This characteristic spectral energy distribution indicates the presence of an optically thin inner cavity within the dust disk believed to mark the disappearance of the primordial massive disk. We present new Herschel Space Observatory PACS spectra of [O I] 63.18 μm for 21 transitional disks. Our survey complements the larger Herschel GASPS program ({sup G}as in Protoplanetary Systems{sup )} by quadrupling the number of transitional disks observed with PACS in this wavelength. [O I] 63.18 μm traces material in the outer regions of the disk, beyond the inner cavity of most transitional disks. We find that transitional disks have [O I] 63.18 μm line luminosities ∼2 times fainter than their full disk counterparts. We self-consistently determine various stellar properties (e.g., bolometric luminosity, FUV excess, etc.) and disk properties (e.g., disk dust mass, etc.) that could influence the [O I] 63.18 μm line luminosity, and we find no correlations that can explain the lower [O I] 63.18 μm line luminosities in transitional disks. Using a grid of thermo-chemical protoplanetary disk models, we conclude that either transitional disks are less flared than full disks or they possess lower gas-to-dust ratios due to a depletion of gas mass. This result suggests that transitional disks are more evolved than their full disk counterparts, possibly even at large radii.

  2. Resolved gas cavities in transitional disks inferred from CO isotopologs with ALMA

    NASA Astrophysics Data System (ADS)

    van der Marel, N.; van Dishoeck, E. F.; Bruderer, S.; Andrews, S. M.; Pontoppidan, K. M.; Herczeg, G. J.; van Kempen, T.; Miotello, A.

    2016-01-01

    Context. Transitional disks around young stars with large dust cavities are promising candidates to look for recently formed, embedded planets. Models of planet-disk interaction predict that young planets clear a gap in the gas while trapping dust at larger radii. Other physical mechanisms might also be responsible for cavities. Previous observations have revealed that gas is still present inside these cavities, but the spatial distribution of this gas remains uncertain. Aims: We present high spatial resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) of 13CO and C18O 3-2 or 6-5 lines of four well-studied transitional disks around pre-main-sequence stars with large dust cavities. The line and continuum observations are used to set constraints on the the gas surface density, specifically on the cavity size and density drop inside the cavity. Methods: The physical-chemical model DALI was used to analyze the gas images of SR21, HD 135344B (also known as SAO 206462), DoAr44, and IRS 48. The main parameters of interest are the size, depth and shape of the gas cavity in each of the disks. CO isotope-selective photodissociation is included to properly constrain the surface density in the outer disk from C18O emission. Results: The gas cavities are up to three times smaller than those of the dust in all four disks. Model fits indicate that the surface density inside the gas cavities decreases by a factor of 100 to 10 000 compared with the surface density profile derived from the outer disk. The data can be fit by either introducing one or two drops in the gas surface density or a surface density profile that increases with radius inside the cavity. A comparison with an analytical model of gap depths by planet-disk interaction shows that the disk viscosities are most likely low, between between 10-3 and 10-4 , for reasonable estimates of planet masses of up to 10 Jupiter masses. Conclusions: The resolved measurements of the gas and dust in

  3. Transition metal catalysis in the generation of petroleum and natural gas. Final report

    SciTech Connect

    Mango, F.D.

    1997-01-21

    This project originated on the premise that natural gas could be formed catalytically in the earth rather than thermally as commonly believed. The intention was to test this hypothetical view and to explore generally the role of sedimentary metals in the generation of light hydrocarbons (C1 - C9). We showed the metalliferous source rocks are indeed catalytic in the generation of natural gas. Various metal compounds in the pure state show the same levels of catalytic activity as sedimentary rocks and the products are identical. Nickel is particularly active among the early transition metals and is projected to remain catalytically robust at all stages of catagenesis. Nickel oxide promotes the formation of n-alkanes in addition to natural gas (NG), demonstrating the full scope of the hypothetical catalytic process: The composition of catalytic gas duplicates the entire range of natural gas, from so-called wet gas to dry gas (60 to 95+ wt % methane), while gas generated thermally is consistently depleted in methane (10 to 60 wt % methane). These results support the view that metal catalysis is a major pathway through which natural gas is formed in the earth.

  4. Transition metal catalysis in the generation of petroleum and natural gas. Progress report, [1992--1993

    SciTech Connect

    Mango, F.

    1993-08-01

    A new hypothesis is introduced for the generation of petroleum and natural gas. The transition metals, activated under the reducing conditions of diagenesis, are proposed as catalysts in the generation of light hydrocarbons. The objective of this proposal is to test that hypothesis. Transition metals (Ni, V, Ti, Co, Fe), in kerogen, porphyrins, and as pure compounds, will be tested under catagenic conditions for catalytic activity in the conversion of normal paraffins and hydrogen into light hydrocarbons. If the hypothesis is correct, kerogenous transition metals should become catalytically active under the reducing conditions of diagenesis and catalyze the conversion of paraffins into the light hydrocarbons seen in petroleum. Moreover, the C{sub 1}-C{sub 4} hydrocarbons generated catalytically should be similar in molecular and isotopic compositions to natural gas.

  5. Lactulose breath test gas production in childhood IBS is associated with intestinal transit and bowel movement frequency

    USDA-ARS?s Scientific Manuscript database

    In adults with irritable bowel syndrome (IBS), bacterial gas production (colonic fermentation) is related to both symptom generation and intestinal transit. Whether gas production affects symptom generation, psychosocial distress, or intestinal transit in childhood IBS is unknown. Children (ages 7-1...

  6. TRANSITION STATE FOR THE GAS-PHASE REACTION OF URANIUM HEXAFLUORIDE WITH WATER

    SciTech Connect

    Garrison, S; James Becnel, J

    2008-03-18

    Density Functional Theory and small-core, relativistic pseudopotentials were used to look for symmetric and asymmetric transitions states of the gas-phase hydrolysis reaction of uranium hexafluoride, UF{sub 6}, with water. At the B3LYP/6-31G(d,p)/SDD level, an asymmetric transition state leading to the formation of a uranium hydroxyl fluoride, U(OH)F{sub 5}, and hydrogen fluoride was found with an energy barrier of +77.3 kJ/mol and an enthalpy of reaction of +63.0 kJ/mol (both including zero-point energy corrections). Addition of diffuse functions to all atoms except uranium led to only minor changes in the structure and relative energies of the reacting complex and transition state. However, a significant change in the product complex structure was found, significantly reducing the enthalpy of reaction to +31.9 kJ/mol. Similar structures and values were found for PBE0 and MP2 calculations with this larger basis set, supporting the B3LYP results. No symmetric transition state leading to the direct formation of uranium oxide tetrafluoride, UOF{sub 4}, was found, indicating that the reaction under ambient conditions likely includes several more steps than the mechanisms commonly mentioned. The transition state presented here appears to be the first published transition state for the important gas-phase reaction of UF{sub 6} with water.

  7. Transition state for the gas-phase reaction of uranium hexafluoride with water.

    PubMed

    Garrison, Stephen L; Becnel, James M

    2008-06-19

    Density functional theory and small-core, relativistic pseudopotentials were used to look for symmetric and asymmetric transition states of the gas-phase hydrolysis reaction of uranium hexafluoride, UF 6, with water. At the B3LYP/6-31G(d,p)/SDD level, an asymmetric transition state leading to the formation of a uranium hydroxyl fluoride, U(OH)F 5, and hydrogen fluoride was found with an energy barrier of +77.3 kJ/mol and an enthalpy of reaction of +63.0 kJ/mol (both including zero-point energy corrections). Addition of diffuse functions to all atoms except uranium led to only minor changes in the structures and relative energies of the reacting complex and transition state. However, a significant change in the structure of the product complex was found, significantly reducing the enthalpy of reaction to +31.9 kJ/mol. Similar structures and values were found for PBE0 and MP2 calculations with this larger basis set, supporting the B3LYP results. No symmetric transition state leading to the direct formation of uranium oxide tetrafluoride, UOF 4, was found, indicating that the reaction under ambient conditions likely includes several more steps than the mechanisms commonly mentioned. The transition state presented here appears to be the first published transition state for the important gas-phase reaction of UF 6 with water.

  8. Gas density drops inside dust cavities of transitional disks around young stars observed with ALMA

    NASA Astrophysics Data System (ADS)

    van der Marel, N.; van Dishoeck, E. F.; Bruderer, S.; Pérez, L.; Isella, A.

    2015-07-01

    Context. Transitional disks with large dust cavities are important laboratories in which to study planet formation and disk evolution. Cold gas may still be present inside these cavities, but quantying this gas is challenging. The gas content is important for constraining the origin of the dust cavity. Aims: We use Atacama Large Millimeter/submillimeter Array (ALMA) observations of 12CO 6-5 and 690 GHz (Band 9) continuum of five well-studied transitional disks. In addition, we analyze previously published Band 7 observations of a disk in the 12CO 3-2 line and 345 GHz continuum. The observations are used to set constraints on the gas and dust surface density profiles, in particular, the drop δgas of the gas density inside the dust cavity. Methods: The physical-chemical modeling code DALI was used to simultaneously analyze the gas and dust images. We modeled SR21, HD 135344B, LkCa15, SR24S, and RX J1615-3255 (Band 9) and J1604-2130 (Band 7). The spectral energy distribution and continuum visibility curve constrain the dust surface density. Then we used the same model to calculate the 12CO emission, which we compared with the observations through spectra and intensity cuts. The amount of gas inside the cavity was quantified by varying the δgas parameter. Results: Model fits to the dust and gas indicate that gas is still present inside the dust cavity for all disks, but at a reduced level. The gas surface density drops inside the cavity by at least a factor 10, while the dust density drops by at least a factor 1000. Disk masses are comparable with previous estimates from the literature, cavity radii are found to be smaller than in the data obtained with the 345 GHz SubMillimeter Array. Conclusions: The derived gas surface density profiles suggest that the cavity was cleared by one or more companions in all cases, which trapped the millimeter-sized dust at the edge of the cavity. Appendix is available in electronic form at http://www.aanda.org

  9. Physical basis for the transition from globular to spray modes in gas metal arc welding

    NASA Astrophysics Data System (ADS)

    Lowke, J. J.

    2009-07-01

    In gas metal arc welding with argon gas, there is a fairly sudden transition current above which diameters of the molten metal drops detached from the welding wire change from being greater than the wire diameter in the 'globular' mode to less than the wire diameter in the 'spray' mode. It is concluded that the primary cause of this transition is that at higher currents the magnetic pinch pressure from current within the molten metal becomes larger than the pressure induced by the surface tension of the molten metal. A formula expressing this condition is I = 2π(γD/μ0)1/2, where I is the transition current, D is the diameter of the wire, γ is the surface tension coefficient of the molten metal and μ0 = 1.26 × 10-6 N A-2 is the permeability of free space. This formula predicts transition currents in fair agreement with previously published experimental results from various authors for both steel and aluminium, for wire diameters varying from 0.4 to 3.0 mm. The formula is not valid for carbon dioxide, helium or hydrogen where, unlike argon, there is arc constriction at the base of the welding wire. Nevertheless, the formula represents a useful approximation for the change in metal transfer modes using various welding wire materials if, as is usual, argon is the principal component of the welding gas.

  10. The CO Transition from Diffuse Molecular Gas to Dense Clouds: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Rice, Johnathan S.; Federman, Steven

    2016-06-01

    The atomic to molecular transitions occurring in diffuse interstellar gas surrounding molecular clouds are affected by the local physical conditions (density and temperature) and the radiation field penetrating the material. The material is closely connected to CO-dark gas, which is not associated with emission from H I at 21 cm or from CO at 2.6 mm. Using optical observations of CH, CH+ and CN absorption from McDonald Observatory and the European Southern Observatory in conjunction with UV observations of CO and H2 absorption from FUSE, we explore the changing environment between diffuse and dense gas, emphasizing trends in column density, excitation temperature, gas density, and velocity structure. This presentation will focus on the completed analysis involving H2 and on the preliminary results of CO for our sample.

  11. 33 CFR 165.110 - Safety and Security Zone; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston, Massachusetts. 165.110 Section 165... Limited Access Areas First Coast Guard District § 165.110 Safety and Security Zone; Liquefied Natural Gas... ahead and one mile astern, and 500 yards on each side of any liquefied natural gas carrier (LNGC) vessel...

  12. 33 CFR 165.110 - Safety and Security Zone; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston, Massachusetts. 165.110 Section 165... Limited Access Areas First Coast Guard District § 165.110 Safety and Security Zone; Liquefied Natural Gas... ahead and one mile astern, and 500 yards on each side of any liquefied natural gas carrier (LNGC) vessel...

  13. 33 CFR 165.110 - Safety and Security Zone; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston, Massachusetts. 165.110 Section 165... Limited Access Areas First Coast Guard District § 165.110 Safety and Security Zone; Liquefied Natural Gas... ahead and one mile astern, and 500 yards on each side of any liquefied natural gas carrier (LNGC) vessel...

  14. 33 CFR 165.110 - Safety and Security Zone; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston, Massachusetts. 165.110 Section 165... Limited Access Areas First Coast Guard District § 165.110 Safety and Security Zone; Liquefied Natural Gas... ahead and one mile astern, and 500 yards on each side of any liquefied natural gas carrier (LNGC) vessel...

  15. 33 CFR 165.110 - Safety and Security Zone; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...; Liquefied Natural Gas Carrier Transits and Anchorage Operations, Boston, Massachusetts. 165.110 Section 165... Limited Access Areas First Coast Guard District § 165.110 Safety and Security Zone; Liquefied Natural Gas... ahead and one mile astern, and 500 yards on each side of any liquefied natural gas carrier (LNGC) vessel...

  16. Investigation of a New Monte Carlo Method for the Transitional Gas Flow

    NASA Astrophysics Data System (ADS)

    Luo, X.; Day, Chr.

    2011-05-01

    The Direct Simulation Monte Carlo method (DSMC) is well developed for rarefied gas flow in transition flow regime when 0.0110, the gas flow is free molecular and can be simulated by the Test Particle Monte Carlo method (TPMC) without any problem even for a complex 3D vacuum system. In this paper we will investigate the approach to extend the TPMC to the transition flow regime by considering the collision between gas molecules as an interaction between a probe molecule and the gas background. Recently this collision mechanism has been implemented into ProVac3D, a new TPMC simulation program developed by Karlsruhe Institute of Technology (KIT). The preliminary simulation result shows a correct nonlinear increasing of the gas flow. However, there is still a quantitative discrepancy with the experimental data, which means further improvement is needed.

  17. Lattice-gas models of phase separation: interfaces, phase transitions, and multiphase flow

    SciTech Connect

    Rothman, D.H. ); Zaleski, S. )

    1994-10-01

    Momentum-conserving lattice gases are simple, discrete, microscopic models of fluids. This review describes their hydrodynamics, with particular attention given to the derivation of macroscopic constitutive equations from microscopic dynamics. Lattice-gas models of phase separation receive special emphasis. The current understanding of phase transitions in these momentum-conserving models is reviewed; included in this discussion is a summary of the dynamical properties of interfaces. Because the phase-separation models are microscopically time irreversible, interesting questions are raised about their relationship to real fluid mixtures. Simulation of certain complex-fluid problems, such as multiphase flow through porous media and the interaction of phase transitions with hydrodynamics, is illustrated.

  18. Compressed Natural Gas (CNG) Transit Bus Experience Survey: April 2009--April 2010

    SciTech Connect

    Adams, R.; Horne, D. B.

    2010-09-01

    This survey was commissioned by the U.S. Department of Energy (DOE) and the National Renewable Energy Laboratory (NREL) to collect and analyze experiential data and information from a cross-section of U.S. transit agencies with varying degrees of compressed natural gas (CNG) bus and station experience. This information will be used to assist DOE and NREL in determining areas of success and areas where further technical or other assistance might be required, and to assist them in focusing on areas judged by the CNG transit community as priority items.

  19. Gas Temperature Demography and the HI-to-H2 Transition in the Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Jameson, Katherine; McClure-Griffiths, Naomi; Liu, Boyang; Staveley-Smith, Lister; Miller Dickey, John; Bolatto, Alberto D.; Dawson, Joanne; Dénes, Helga; Li, Di; Stanimirovic, Snezana; Wolfire, Mark G.; Wong, Tony H.

    2017-06-01

    Given their proximity and low metallicity, the Magellanic Clouds provide the ideal laboratory to study the evolution of gas in the interstellar medium. We present first results from a new HI and OH absorption line study using the ATCA to measure the warm-to-cold atomic fraction and the atomic-to-molecular transition in the Large and Small Magellanic Clouds (LMC and SMC, respectively). The survey targets 48 sources in the LMC and 29 sources in the SMC, which covers more sources at higher senstitivity and spectral resolutin than previous absorption line measurement studies. We decompose the emission and absorption spectra using the autonomous gaussian decomposition software GaussPy (Lindner et al. 2015), which allows us to measure the spin temperature and optical depth of the HI gas. These measurements of the optical depth allow us to constrain the amount of "CO-faint" gas that is optically thick HI gas. Initial analysis indicates that we measure higher spin temperatures than the previous studies (Dickey et al. 1994, Marx-Zimmer et al. 2000), and cold atomic gas fractions of ~20%. We currently have no detections of OH absorption and an upper limit on the column density of molecular gas in the targeted lines of sight of ~few x 1022 cm-2, which is consistent with the dust-based molecular gas estimates.

  20. Long noncoding RNA GAS5 affects cell proliferation and predicts a poor prognosis in patients with colorectal cancer.

    PubMed

    Yin, Dandan; He, Xuezhi; Zhang, Erbao; Kong, Rong; De, Wei; Zhang, Zhihong

    2014-11-01

    Colorectal cancer (CRC) is the third most common type of cancer worldwide. Recent studies have shown that lncRNAs play important roles in carcinogenesis. The aim of this study was to explore the role of lncRNA GAS5 in CRC. Real-time PCR was performed to investigate the expression of GAS5 in tumor tissues and corresponding non-tumor colorectal tissues from 66 patients with CRC. The lower expression of GAS5 was significantly correlated with large tumor size, low histological grade and advanced TNM stage. Multivariate analyses revealed that GAS5 expression served as an independent predictor for overall survival (P = 0.034). Further experiments revealed that overexpressed GAS5 significantly repressed the proliferation both in vitro and in vivo. In conclusion, our results suggest that GAS5, as a growth regulator, may serve as a candidate prognostic biomarker in human colorectal cancer.

  1. Energetics of gas-surface interactions in transitional flows at entry velocities

    NASA Technical Reports Server (NTRS)

    Wilmoth, R. G.; Moss, J. N.; Dogra, V. K.

    1991-01-01

    The direct simulation Monte Carlo (DSMC) method has been used to calculate the molecular velocity and energy distributions of molecules striking a surface after traversing a shock layer in hypersonic transitional flow. The calculations were performed for a 1.6-m-diameter sphere at a nominal velocity for re-entry of 7.5 km/s over an altitude range of 130 to 90 km. Real gas effects and chemical reactions were included in the DSMC simulations. Results are presented for these conditions and the need for gas-surface interaction experiments is discussed.

  2. Liquid-gas phase transitions in a multicomponent nuclear system with Coulomb and surface effects

    SciTech Connect

    Lee, S. J.; Mekjian, A. Z.

    2001-04-01

    The liquid-gas phase transition is studied in a multicomponent nuclear system using a local Skyrme interaction with Coulomb and surface effects. Some features are qualitatively the same as the results of Mu''ller and Serot where a relativistic mean field was used without Coulomb and surface effects. Surface tension brings the coexistence binodal surface to lower pressure. The Coulomb interaction makes the binodal surface smaller and causes another pair of binodal points at low pressure and large proton fraction with fewer protons in the liquid phase and more protons in the gas phase.

  3. WASP-37b: A 1.8 M{sub J} EXOPLANET TRANSITING A METAL-POOR STAR

    SciTech Connect

    Simpson, E. K.; Faedi, F.; Barros, S. C. C.; Pollacco, D.; Todd, I.; McCormac, J.; Brown, D. J. A.; Cameron, A. Collier; Miller, G. R. M.; Hebb, L.; Smalley, B.; Anderson, D. R.; Butters, O. W.; Hebrard, G.; Boisse, I.; Santerne, A.; Street, R. A.; Skillen, I.; Triaud, A. H. M. J.; Bento, J.

    2011-01-15

    We report on the discovery of WASP-37b, a transiting hot Jupiter orbiting an m{sub v} = 12.7 G2-type dwarf, with a period of 3.577469 {+-} 0.000011 d, transit epoch T{sub 0} = 2455338.6188 {+-} 0.0006 (HJD; dates throughout the paper are given in Coordinated Universal Time (UTC)), and a transit duration 0.1304{sup +0.0018}{sub -0.0017} d. The planetary companion has a mass M{sub p} = 1.80 {+-} 0.17 M{sub J} and radius R{sub p} = 1.16{sup +0.07}{sub -0.06} R{sub J}, yielding a mean density of 1.15{sup +0.12}{sub -0.15} {rho}{sub J}. From a spectral analysis, we find that the host star has M{sub *} = 0.925 {+-} 0.120 M{sub sun}, R{sub *} = 1.003 {+-} 0.053 R{sub sun}, T{sub eff} = 5800 {+-} 150 K, and [Fe/H] = -0.40 {+-} 0.12. WASP-37 is therefore one of the lowest metallicity stars to host a transiting planet.

  4. Coagulation of charged microparticles in neutral gas and charge-induced gel transitions.

    PubMed

    Ivlev, A V; Morfill, G E; Konopka, U

    2002-11-04

    Coagulation of charged particles was studied using the mean-field Smoluchowski equation. The coagulation equation was generalized for the case of a conserved system of charged particles. It was shown that runaway cluster growth (gelation) solutions exist if the charge-dipole (induced) interaction of clusters is included. When clusters are in thermal equilibrium with the ambient gas, the charge-dipole interaction dramatically enhances the aggregation process and considerably increases the likelihood of a gelation transition.

  5. Transition metal catalysis in the generation of petroleum and natural gas

    SciTech Connect

    Mango, F.D. )

    1992-01-01

    Certain ratios of light hydrocarbons remain virtually invariant over the course of petroleum generation, indicating steady-state catalysis rather than thermal cracking as the central feature to the mechanism of petroleum generation. Although the evidence for catalytic intervention is now compelling, the nature of the catalytic agent, its mode of activation and action are not clear. The author proposes that the transition metals, activated in the lipophilic domains of kerogen, are the catalytic agents in the conversion of normal paraffins into light hydrocarbons and natural gas. The process proceeds through specific catalytic steps involving 3-, 5-, and 6-carbon ring-closures and the cleavage of carbon-carbon bonds in the key steps. This hypothesis is analyzed in the context of published literature on catalysis by Ni, V, Ti, Co, and related transition metals. Activated under anaerobic conditions, these metals express extraordinary catalytic activity in each of the postulated steps. Moreover, metal-catalysis provides a reasonable kinetic pathway through which hydrogen and normal paraffins may combine to form a methane-enriched a natural gas. Given the anaerobic conditions of diagenesis and a kerogenous source of hydrogen, it is concluded that the transition metals, under catagenic conditions, are potentially active catalysts in the conversion of hydrogen and paraffins into light hydrocarbons and natural gas.

  6. Gas-phase activation of methane by ligated transition-metal cations

    PubMed Central

    Schröder, Detlef; Schwarz, Helmut

    2008-01-01

    Motivated by the search for ways of a more efficient usage of the large, unexploited resources of methane, recent progress in the gas-phase activation of methane by ligated transition-metal ions is discussed. Mass spectrometric experiments demonstrate that the ligands can crucially influence both reactivity and selectivity of transition-metal cations in bond-activation processes, and the most reactive species derive from combinations of transition metals with the electronegative elements fluorine, oxygen, and chlorine. Furthermore, the collected knowledge about intramolecular kinetic isotope effects associated with the activation of C–H(D) bonds of methane can be used to distinguish the nature of the bond activation as a mere hydrogen-abstraction, a metal-assisted mechanism or more complex reactions such as formation of insertion intermediates or σ-bond metathesis. PMID:18955709

  7. Calculators for Estimating Greenhouse Gas Emissions from Public Transit Agency Vehicle Fleet Operations

    SciTech Connect

    Weigel, Brent; Southworth, Frank; Meyer, Michael D

    2010-01-01

    This paper reviews calculation tools available for quantifying the greenhouse gas emissions associated with different types of public transit service, and their usefulness in helping a transit agency to reduce its carbon footprint through informed vehicle and fuel procurement decisions. Available calculators fall into two categories: registry/inventory based calculators most suitable for standardized voluntary reporting, carbon trading, and regulatory compliance; and multi-modal life cycle analysis calculators that seek comprehensive coverage of all direct and indirect emissions. Despite significant progress in calculator development, no single calculator as yet contains all of the information needed by transit agencies to develop a truly comprehensive, life cycle analysis-based accounting of the emissions produced by its vehicle fleet operations, and for a wide range of vehicle/fuel technology options.

  8. Determining magnetic phase transitions temperatures in working magnetocaloric coolers bodies and gas cryorefrigerators regenerators

    NASA Astrophysics Data System (ADS)

    Karagusov, V. I.; Mayankov, I. V.

    2017-08-01

    Due to magnetic phase transitions rare-earth materials possess unique properties near the Curie and Neel temperatures, such as the magneto-caloric effect, the abnormally high heat capacity, the magnetic susceptibility and permeability extremes. Using rare earth materials in gas cryogenic refrigerators regenerators increases the efficiency, reduces the power consumption and allows reaching helium temperatures. The magneto-caloric effect has also extreme values near the Curie and Neel temperatures. The paper presents theoretical and experimental methods allowing to determine magnetic phase transitions temperatures in a wide range of low temperature materials with a various rare-earth components content and expected thermophysical properties of a certain rare-earth materials composition at the temperatures based on starting pure metals characteristics. The results analysis has shown that magnetic phase transitions temperatures are a linear function of the components concentration. Moreover, heat capacity values and MCE also depend linearly on the starting components concentration, which simplifies calculations significantly.

  9. Developing a Natural Gas-Powered Bus Rapid Transit Service. A Case Study

    SciTech Connect

    Mitchell, George

    2015-11-01

    The Roaring Fork Transit Authority (RFTA) and its VelociRFTA Bus Rapid Transit (BRT) program are unique in many ways. For example, VelociRFTA was the first rural BRT system in the United States and the operational environment of the VelociRFTA BRT is one of the most severe in the country, with extreme winter temperatures and altitudes close to 8,000 feet. RFTA viewed high altitude operation as the most challenging characteristic when it began considering the use of natural gas. RFTA is the second-largest public transit system in Colorado behind Denver's Regional Transportation District (RTD), and it is one of the largest rural public transit systems in the country. In 2013, RFTA accepted delivery of 22 new compressed natural gas (CNG) buses that went into service after completion of maintenance and refueling facilities earlier that year. This paper examines the lessons learned from RFTA's experience of investigating--and ultimately choosing--CNG for their new BRT program and focuses on the unique environment of RFTA's BRT application; the decision process to include CNG fueling in the project; unforeseen difficulties encountered in the operation of CNG buses; public perception; cost comparison to competing fuels; and considerations for indoor fueling facilities and project funding.

  10. Developing a Natural Gas-Powered Bus Rapid Transit Service: A Case Study

    SciTech Connect

    Mitchell, G.

    2015-11-03

    The Roaring Fork Transit Authority (RFTA) and its VelociRFTA Bus Rapid Transit (BRT) program are unique in many ways. For example, VelociRFTA was the first rural BRT system in the United States and the operational environment of the VelociRFTA BRT is one of the most severe in the country, with extreme winter temperatures and altitudes close to 8,000 feet. RFTA viewed high altitude operation as the most challenging characteristic when it began considering the use of natural gas. RFTA is the second-largest public transit system in Colorado behind Denver's Regional Transportation District (RTD), and it is one of the largest rural public transit systems in the country. In 2013, RFTA accepted delivery of 22 new compressed natural gas (CNG) buses that went into service after completion of maintenance and refueling facilities earlier that year. This paper examines the lessons learned from RFTA's experience of investigating--and ultimately choosing--CNG for their new BRT program and focuses on the unique environment of RFTA's BRT application; the decision process to include CNG fueling in the project; unforeseen difficulties encountered in the operation of CNG buses; public perception; cost comparison to competing fuels; and considerations for indoor fueling facilities and project funding.

  11. Onset conditions for gas phase reaction and nucleation in the CVD of transition metal oxides

    NASA Technical Reports Server (NTRS)

    Collins, J.; Rosner, D. E.; Castillo, J.

    1992-01-01

    A combined experimental/theoretical study is presented of the onset conditions for gas phase reaction and particle nucleation in hot substrate/cold gas CVD of transition metal oxides. Homogeneous reaction onset conditions are predicted using a simple high activation energy reacting gas film theory. Experimental tests of the basic theory are underway using an axisymmetric impinging jet CVD reactor. No vapor phase ignition has yet been observed in the TiCl4/O2 system under accessible operating conditions (below substrate temperature Tw = 1700 K). The goal of this research is to provide CVD reactor design and operation guidelines for achieving acceptable deposit microstructures at the maximum deposition rate while simultaneously avoiding homogeneous reaction/nucleation and diffusional limitations.

  12. Onset conditions for gas phase reaction and nucleation in the CVD of transition metal oxides

    NASA Technical Reports Server (NTRS)

    Collins, J.; Rosner, D. E.; Castillo, J.

    1992-01-01

    A combined experimental/theoretical study is presented of the onset conditions for gas phase reaction and particle nucleation in hot substrate/cold gas CVD of transition metal oxides. Homogeneous reaction onset conditions are predicted using a simple high activation energy reacting gas film theory. Experimental tests of the basic theory are underway using an axisymmetric impinging jet CVD reactor. No vapor phase ignition has yet been observed in the TiCl4/O2 system under accessible operating conditions (below substrate temperature Tw = 1700 K). The goal of this research is to provide CVD reactor design and operation guidelines for achieving acceptable deposit microstructures at the maximum deposition rate while simultaneously avoiding homogeneous reaction/nucleation and diffusional limitations.

  13. Atom probe study of Cu-poor to Cu-rich transition during Cu(In,Ga)Se2 growth

    NASA Astrophysics Data System (ADS)

    Couzinie-Devy, F.; Cadel, E.; Barreau, N.; Arzel, L.; Pareige, P.

    2011-12-01

    Atomic scale chemistry of polycrystalline Cu(In,Ga)Se2 (CIGSe) thin film has been characterized at key points of the 3-stage process using atom probe tomography. 3D atom distributions have been reconstructed when the layer is Cu-poor ([Cu]/([Ga] + [In]) < 1), Cu-rich ([Cu]/([Ga] + [In]) > 1), and at the end of the process. Particular attention has been devoted to grain boundary composition and Na atomic distribution within the CIGSe layer. Significant variation of composition is highlighted during the growing process, providing fundamental information helping the understanding of high efficiency CIGSe formation.

  14. Boundary-Layer Transition on a Slender Cone in Hypervelocity Flow with Real Gas Effects

    NASA Astrophysics Data System (ADS)

    Jewell, Joseph Stephen

    The laminar to turbulent transition process in boundary layer flows in thermochemical nonequilibrium at high enthalpy is measured and characterized. Experiments are performed in the T5 Hypervelocity Reflected Shock Tunnel at Caltech, using a 1 m length 5-degree half angle axisymmetric cone instrumented with 80 fast-response annular thermocouples, complemented by boundary layer stability computations using the STABL software suite. A new mixing tank is added to the shock tube fill apparatus for premixed freestream gas experiments, and a new cleaning procedure results in more consistent transition measurements. Transition location is nondimensionalized using a scaling with the boundary layer thickness, which is correlated with the acoustic properties of the boundary layer, and compared with parabolized stability equation (PSE) analysis. In these nondimensionalized terms, transition delay with increasing CO2 concentration is observed: tests in 100% and 50% CO2, by mass, transition up to 25% and 15% later, respectively, than air experiments. These results are consistent with previous work indicating that CO2 molecules at elevated temperatures absorb acoustic instabilities in the MHz range, which is the expected frequency of the Mack second-mode instability at these conditions, and also consistent with predictions from PSE analysis. A strong unit Reynolds number effect is observed, which is believed to arise from tunnel noise. NTr for air from 5.4 to 13.2 is computed, substantially higher than previously reported for noisy facilities. Time- and spatially-resolved heat transfer traces are used to track the propagation of turbulent spots, and convection rates at 90%, 76%, and 63% of the boundary layer edge velocity, respectively, are observed for the leading edge, centroid, and trailing edge of the spots. A model constructed with these spot propagation parameters is used to infer spot generation rates from measured transition onset to completion distance. Finally, a novel

  15. Upregulation of H19 indicates a poor prognosis in gallbladder carcinoma and promotes epithelial-mesenchymal transition

    PubMed Central

    Wang, Shou-Hua; Wu, Xiao-Cai; Zhang, Ming-Di; Weng, Ming-Zhe; Zhou, Di; Quan, Zhi-Wei

    2016-01-01

    The imprinted oncofetal long non-coding RNA H19 has been reported to be involved in many kinds of human cancers. However, whether lncRNA H19 implicate in oncogenesis and cancer progression in gallbladder cancer remain largely unknown. In the present study, compared with adjacent normal tissues, the level of H19 was significantly upregulated in gallbladder cancer tissues and was positively associated with lymphatic metastasis and tumor size. The overall survival is shorter in those who had higher H19 expression among GBC patients. In vitro, both TGF-β1 and IL-6 treatment induced upregulation of H19, downregulated the protein level of E-cadherin while increased Vimentin, indicating an epithelial-mesenchymal transition (EMT) phenotype in GBC. The overexpression of H19 in GBC cells enhanced tumor invasion and promoted EMT by upregulated transcription factor Twist1. On the contrary, Loss of function studies indicated that H19 interference in GBC suppressed tumor cell invasion and promoted mesenchymal-epithelial transition (MET) via suppressing Twist expression. In vivo, the volume of the tumors in H19-inteference group was significantly decreased compared to those in the control group of nude mice. Both western-blot and immunohistochemistry confirmed that a MET phenotype existed in the H19 interference group when compared to control group. These results defined H19 as a novel prognostic factor for GBC, and indicated that it might play important regulatory roles in the EMT process. PMID:27073719

  16. "Could charm (& τ) transitions be the `poor princess' providing a deeper understanding of fundamental dynamics ?" or: "Finding novel forces"

    NASA Astrophysics Data System (ADS)

    Bigi, Ikaros I.

    2015-06-01

    We know that our Universe is composed of only ˜ 4.5% "known" matter; therefore, our understanding is incomplete. This can be seen directly in the case of neutrino oscillations (without even considering potential other universes). Charm quarks have had considerable impact on our understanding of known matter, and quantum chromodynamics (QCD) is the only local quantum field theory to describe strong forces. It is possible to learn novel lessons concerning strong dynamics by measuring rates around the thresholds of [ Q¯ Q] states with Q = b, c. Furthermore, these states provide us with gateways towards new dynamics (ND), where we must transition from "accuracy" to "precision" eras. Finally, we can make connections with τ transitions and, perhaps, with dark matter. Charm dynamics acts as a bridge between the worlds of light- and heavy-flavor hadrons (namely, beauty hadrons), and finding regional asymmetries in many-body final states may prove to be a "game changer". There are several different approaches to achieving these goals: for example, experiments such as the Super Tau-Charm Factory, Super Beauty Factory, and the Super Z 0 Factory act as gatekeepers - and deeper thinking regarding symmetries.

  17. Quantifying the Gas Inside Dust Cavities in Transitional Disks: Implications for Young Planets

    NASA Astrophysics Data System (ADS)

    van Dishoeck, E. F.; van der Marel, N.; Bruderer, S.; Pinilla, P.

    2015-12-01

    ALMA observations of a small sample of transitional disks with large dust cavities observed in Cycle 0 and 1 are summarized. The gas and dust surface density structures are inferred from the continuum and 12CO, 13CO and C18O line data using the DALI physical-chemical code. Thanks to its ability to self-shield, CO can survive inside dust cavities in spite of being exposed to intense UV radiation and can thus be used as a probe of the gas structure. Modeling of the existing data shows that gas is present inside the dust cavities in all cases, but at a reduced level compared with the gas surface density profile of the outer disk. The gas density decrease inside the dust cavity radius by factors of up to 104 suggests clearing by one or more planetary-mass companions. The accompanying pressure bumps naturally lead to trapping of the mm-sized dust grains observed in the ALMA images.

  18. Physical understanding of gas-liquid annular flow and its transition to dispersed droplets

    NASA Astrophysics Data System (ADS)

    Kumar, Parmod; Das, Arup Kumar; Mitra, Sushanta K.

    2016-07-01

    Transformation from annular to droplet flow is investigated for co-current, upward gas-liquid flow through a cylindrical tube using grid based volume of fluid framework. Three transitional routes, namely, orificing, rolling, and undercutting are observed for flow transformation at different range of relative velocities between the fluids. Physics behind these three exclusive phenomena is described using circulation patterns of gaseous phase in the vicinity of a liquid film which subsequently sheds drop leading towards transition. Orifice amplitude is found to grow exponentially towards the core whereas it propagates in axial direction in a parabolic path. Efforts have been made to fit the sinusoidal profile of wave structure with the numerical interface contour at early stages of orificing. Domination of gas inertia over liquid flow has been studied in detail at the later stages to understand the asymmetric shape of orifice, leading towards lamella formation and droplet generation. Away from comparative velocities, circulations in the dominant phase dislodge the drop by forming either a ligament (rolling) or a bag (undercut) like protrusion in liquid. Study of velocity patterns in the plane of droplet dislodge reveals the underlying physics behind the disintegration and its dynamics at the later stages. Using numerical phase distributions, rejoining of dislodged droplet with liquid film as post-rolling consequences has been also proposed. A flow pattern map showing the transitional boundaries based on the physical mechanism is constructed for air-water combination.

  19. Caloric curve for nuclear liquid-gas phase transition in relativistic mean-field hadronic model

    NASA Astrophysics Data System (ADS)

    Parvan, A. S.

    2012-08-01

    The main thermodynamical properties of the first order phase transition of the relativistic mean-field (RMF) hadronic model were explored in the isobaric, the canonical and the grand canonical ensembles on the basis of the method of the thermodynamical potentials and their first derivatives. It was proved that the first order phase transition of the RMF model is the liquid-gas type one associated with the Gibbs free energy G. The thermodynamical potential G is the piecewise smooth function and its first order partial derivatives with respect to variables of state are the piecewise continuous functions. We have found that the energy in the caloric curve is discontinuous in the isobaric and the grand canonical ensembles at fixed values of the pressure and the chemical potential, respectively, and it is continuous, i.e. it has no plateau, in the canonical and microcanonical ensembles at fixed values of baryon density, while the baryon density in the isotherms is discontinuous in the isobaric and the canonical ensembles at fixed values of the temperature. The general criterion for the nuclear liquid-gas phase transition in the canonical ensemble was identified.

  20. METAL-POOR, COOL GAS IN THE CIRCUMGALACTIC MEDIUM OF A z = 2.4 STAR-FORMING GALAXY: DIRECT EVIDENCE FOR COLD ACCRETION?

    SciTech Connect

    Crighton, Neil H. M.; Hennawi, Joseph F.; Prochaska, J. Xavier

    2013-10-20

    In our current galaxy formation paradigm, high-redshift galaxies are predominantly fueled by accretion of cool, metal-poor gas from the intergalactic medium. Hydrodynamical simulations predict that this material should be observable in absorption against background sightlines within a galaxy's virial radius, as optically thick Lyman limit systems (LLSs) with low metallicities. Here we report the discovery of exactly such a strong metal-poor absorber at an impact parameter R = 58 kpc from a star-forming galaxy at z = 2.44. Besides strong neutral hydrogen (N{sub H{sup 0}}=10{sup 19.50±0.16} cm{sup -2}) we detect neutral deuterium and oxygen, allowing a precise measurement of the metallicity: log{sub 10}(Z/Z {sub ☉}) = –2.0 ± 0.17, or (7-15) × 10{sup –3} solar. Furthermore, the narrow deuterium linewidth requires a cool temperature <20,000 K. Given the striking similarities between this system and the predictions of simulations, we argue that it represents the direct detection of a high-redshift cold-accretion stream. The low-metallicity gas cloud is a single component of an absorption system exhibiting a complex velocity, ionization, and enrichment structure. Two other components have metallicities >0.1 solar, 10 times larger than the metal-poor component. We conclude that the photoionized circumgalactic medium (CGM) of this galaxy is highly inhomogeneous: the majority of the gas is in a cool, metal-poor and predominantly neutral phase, but the majority of the metals are in a highly ionized phase exhibiting weak neutral hydrogen absorption but strong metal absorption. If such inhomogeneity is common, then high-resolution spectra and detailed ionization modeling are critical to accurately appraise the distribution of metals in the high-redshift CGM.

  1. Simulation of the transition radiation detection conditions in the ATLAS TRT detector filled with argon and krypton gas mixtures

    SciTech Connect

    Boldyrev, A. S.; Maevskiy, A. S.

    2015-12-15

    Performance of the Transition Radiation Tracker (TRT) at the ATLAS experiment with argon and krypton gas mixtures was simulated. The efficiency of transition radiation registration, which is necessary for electron identification, was estimated along with the electron identification capabilities under such conditions.

  2. Downregulation of FBP1 Promotes Tumor Metastasis and Indicates Poor Prognosis in Gastric Cancer via Regulating Epithelial-Mesenchymal Transition.

    PubMed

    Li, Jing; Wang, Ying; Li, Qing-Guo; Xue, Jin-Jun; Wang, Zhu; Yuan, Xin; Tong, Jian-Dong; Xu, Li-Chun

    2016-01-01

    Recent studies indicated that some glycolytic enzymes are complicated, multifaceted proteins rather than simple components of the glycolytic pathway. FBP1 plays a vital role in glucose metabolism, but its role in gastric cancer tumorigenesis and metastasis has not been fully understood. The prognostic value of FBP1 was first studied in The Cancer Genome Atlas (TCGA) database and validated in in-house database. The effect of FBP1 on cell proliferation and metastasis was examined in vitro. Nonparametric test and Log-rank test were used to evaluate the clinical significance of FBP1 expression. In the TCGA cohort, FBP1 mRNA level were shown to be predictive of overall survival in gastric cancer (P = 0.029). In the validation cohort, FBP1 expression were inversely correlated with advanced N stage (P = 0.021) and lymphovascular invasion (P = 0.011). Multivariate Cox regression analysis demonstrated that FBP1 was an independent predictor for both overall survival (P = 0.004) and disease free survival (P<0.001). Functional studies demonstrated that ectopic FBP1 expression inhibited proliferation and invasion in gastric cancer cells, while silencing FBP1 expression had opposite effects (P<0.05). Mechanically, FBP1 serves as a tumor suppressor by inhibiting epithelial-mesenchymal transition (EMT). Downregulation of FBP1 promotes gastric cancer metastasis by facilitating EMT and acts as a potential prognostic factor and therapeutic target in gastric cancer.

  3. Downregulation of FBP1 Promotes Tumor Metastasis and Indicates Poor Prognosis in Gastric Cancer via Regulating Epithelial-Mesenchymal Transition

    PubMed Central

    Li, Qing-Guo; Xue, Jin-Jun; Wang, Zhu; Yuan, Xin; Tong, Jian-Dong; Xu, Li-Chun

    2016-01-01

    Background Recent studies indicated that some glycolytic enzymes are complicated, multifaceted proteins rather than simple components of the glycolytic pathway. FBP1 plays a vital role in glucose metabolism, but its role in gastric cancer tumorigenesis and metastasis has not been fully understood. Methods The prognostic value of FBP1 was first studied in The Cancer Genome Atlas (TCGA) database and validated in in-house database. The effect of FBP1 on cell proliferation and metastasis was examined in vitro. Nonparametric test and Log-rank test were used to evaluate the clinical significance of FBP1 expression. Results In the TCGA cohort, FBP1 mRNA level were shown to be predictive of overall survival in gastric cancer (P = 0.029). In the validation cohort, FBP1 expression were inversely correlated with advanced N stage (P = 0.021) and lymphovascular invasion (P = 0.011). Multivariate Cox regression analysis demonstrated that FBP1 was an independent predictor for both overall survival (P = 0.004) and disease free survival (P<0.001). Functional studies demonstrated that ectopic FBP1 expression inhibited proliferation and invasion in gastric cancer cells, while silencing FBP1 expression had opposite effects (P<0.05). Mechanically, FBP1 serves as a tumor suppressor by inhibiting epithelial-mesenchymal transition (EMT). Conclusions Downregulation of FBP1 promotes gastric cancer metastasis by facilitating EMT and acts as a potential prognostic factor and therapeutic target in gastric cancer. PMID:27978536

  4. The role of gas phase reactions in the deflagration-to-detonation transition of high energy propellants

    NASA Technical Reports Server (NTRS)

    Boggs, T. L.; Price, C. F.; Atwood, A. I.; Zurn, D. E.; Eisel, J. L.; Derr, R. L.

    1980-01-01

    The inadequacies of the two commonly used assumptions are shown, along with the need for considering gas phase reactions. Kinetic parameters that describe the gas phase reactions for several ingredients are provided, and the first steps in convective combustion leading to deflagration to detonation transition are described.

  5. The role of gas phase reactions in the deflagration-to-detonation transition of high energy propellants

    NASA Technical Reports Server (NTRS)

    Boggs, T. L.; Price, C. F.; Atwood, A. I.; Zurn, D. E.; Eisel, J. L.; Derr, R. L.

    1980-01-01

    The inadequacies of the two commonly used assumptions are shown, along with the need for considering gas phase reactions. Kinetic parameters that describe the gas phase reactions for several ingredients are provided, and the first steps in convective combustion leading to deflagration to detonation transition are described.

  6. DYNAMIC MODELING STRATEGY FOR FLOW REGIME TRANSITION IN GAS-LIQUID TWO-PHASE FLOWS

    SciTech Connect

    X. Wang; X. Sun; H. Zhao

    2011-09-01

    In modeling gas-liquid two-phase flows, the concept of flow regime has been used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are often flow regime dependent. Currently, the determination of the flow regimes is primarily based on flow regime maps or transition criteria, which are developed for steady-state, fully-developed flows and widely applied in nuclear reactor system safety analysis codes, such as RELAP5. As two-phase flows are observed to be dynamic in nature (fully-developed two-phase flows generally do not exist in real applications), it is of importance to model the flow regime transition dynamically for more accurate predictions of two-phase flows. The present work aims to develop a dynamic modeling strategy for determining flow regimes in gas-liquid two-phase flows through the introduction of interfacial area transport equations (IATEs) within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation and destruction of the interfacial area, such as the fluid particle (bubble or liquid droplet) disintegration, boiling and evaporation; and fluid particle coalescence and condensation, respectively. For the flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shape (which are correlated), namely small bubbles and large bubbles. A preliminary approach to dynamically identifying the flow regimes is provided, in which discriminators are based on the predicted information, such as the void fraction and interfacial area concentration of small bubble and large bubble groups. This method is expected to be applied to computer codes to improve their predictive capabilities of gas-liquid two-phase flows, in particular for the applications in

  7. Clean air program: Compressed natural gas safety in transit operations. Final report

    SciTech Connect

    Friedman, D.M.; Malcosky, N.D.

    1995-10-01

    This report examines the safety issues relating to the use of Compressed Natural Gas (CNG) in transit service. The safety issues were determined by on-site surveys performed by Battelle of Columbus, Ohio and Science Applications International Corporation (SAIC) of McLean, Virginia of seven transit agencies using CNG. The survey consisted of: (1) extensive interviews; (2) review of records, procedures, and plans relating to safety; (3) examination of facilities and equipment; (4) observation of operations including fueling, maintenance, morning start-up, and revenue service; and (5) measurements of methane concentrations in the air where the buses are being fueled or stored. Interviews included all job categories associated with management, operations, safety, maintenance, acquisition, and support.

  8. Buoyancy Effects on Flow Transition in Hydrogen Gas Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Albers, Burt W.; Agrawal, Ajay K.; Griffin, DeVon (Technical Monitor)

    2000-01-01

    Experiments were performed in earth-gravity to determine how buoyancy affected transition from laminar to turbulent flow in hydrogen gas jet diffusion flames. The jet exit Froude number characterizing buoyancy in the flame was varied from 1.65 x 10(exp 5) to 1.14 x 10(exp 8) by varying the operating pressure and/or burner inside diameter. Laminar fuel jet was discharged vertically into ambient air flowing through a combustion chamber. Flame characteristics were observed using rainbow schlieren deflectometry, a line-of-site optical diagnostic technique. Results show that the breakpoint length for a given jet exit Reynolds number increased with increasing Froude number. Data suggest that buoyant transitional flames might become laminar in the absence of gravity. The schlieren technique was shown as effective in quantifying the flame characteristics.

  9. Thermal phase transitions in a honeycomb lattice gas with three-body interactions.

    PubMed

    Lohöfer, Maximilian; Bonnes, Lars; Wessel, Stefan

    2013-11-01

    We study the thermal phase transitions in a classical (hard-core) lattice gas model with nearest-neighbor three-body interactions on the honeycomb lattice, based on parallel tempering Monte Carlo simulations. This system realizes incompressible low-temperature phases at fractional fillings of 9/16, 5/8, and 3/4 that were identified in a previous study of a related quantum model. In particular, both the 9/16 and the 5/8 phase exhibit an extensive ground-state degeneracy reflecting the frustrated nature of the three-body interactions on the honeycomb lattice. The thermal melting of the 9/16 phase is found to be a first-order, discontinuous phase transition. On the other hand, from the thermodynamic behavior we obtain indications for a four-states Potts-model thermal transition out of the 5/8 phase. We find that this thermal Potts-model transition relates to the selection of one out of four extensive sectors within the low-energy manifold of the 5/8 phase, which we obtain via an exact mapping of the ground-state manifold to a hard-core dimer model on an embedded honeycomb superlattice.

  10. Multiple phase transitions in extended hard-core lattice gas models in two dimensions.

    PubMed

    Nath, Trisha; Rajesh, R

    2014-07-01

    We study the k-NN hard-core lattice gas model in which the first k next-nearest-neighbor sites of a particle are excluded from occupation by other particles on a two-dimensional square lattice. This model is the lattice version of the hard-disk system with increasing k corresponding to decreasing lattice spacing. While the hard-disk system is known to undergo a two-step freezing process with increasing density, the lattice model has been known to show only one transition. Here, based on Monte Carlo simulations and high-density expansions of the free energy and density, we argue that for k = 4,10,11,14,⋯, the lattice model undergoes multiple transitions with increasing density. Using Monte Carlo simulations, we confirm the same for k = 4,...,11. This, in turn, resolves an existing puzzle as to why the 4-NN model has a continuous transition against the expectation of a first-order transition.

  11. Application of four dimensional matrix for thermal analysis of Slovak transit gas pipeline by program FENIX

    NASA Astrophysics Data System (ADS)

    Széplaky, Dávid; Varga, Augustín

    2016-06-01

    The contribution describes the principle of the FENIX program operation, which was designed to determine the temperature field of the transit pipeline for the transportation of natural gas. The program itself consists of several modules which are reciprocally linked. The basis of the program is the elementary balance method by means of which the unsteady heat transfer is assigned in several layers in different directions. The first step was to assess both the pressure and temperature of the natural gas mode, the second step is to determine the heat transfer through the walls of the pipes, and the last one is to determine the distribution of the temperature field in the surroundings of the pipeline.

  12. Interfacial Friction in Gas-Liquid Annular Flow: Analogies to Full and Transition Roughness

    SciTech Connect

    Bauer, R.C.; Beus, S.G.; Fore, L.B.

    1999-03-01

    New film thickness and pressure gradient data were obtained in a 5.08 by 101.6 mm duct for nitrogen and water in annular flow. Pressures of 3.4 and 17 atm and temperatures of 38 and 93 C were used to vary the gas density and liquid viscosity. These data are used to compute interfacial shear stresses and interfacial friction factors for comparison with several accepted literature correlations. These comparisons are reasonable for small values of the relative film thickness. However, the new data cover conditions not approached by the data used to construct those correlations. By combining the current data with the results of two other comprehensive modern experimental studies, a new correlation for the interfacial friction factor has been developed. This correlation adds elements of transition roughness to Wallis' fully-rough analogy to better predict interfacial friction factors over a wide range of gas Reynolds numbers and liquid film thicknesses.

  13. Clean air program: Liquefied natural gas safety in transit operations. Final report

    SciTech Connect

    Friedman, D.M.; Malcosky, N.D.

    1996-03-01

    The report examines the safety issues relating to the use of Liquefied natural Gas (LNG) in transit service. The surveys consisted of: (1) extensive interviews; (2) review of recrods, procedures, and plans relating to safety; (3) examination of facilities and equipment; (4) observations of operations including fueling, maintenance, morning start-up, and revenue service; (5) measurement of methane concentrations in the air where the buses are being fueled or stored. Interviews included all job categories associated with management, operations, safety, maintenance, acquisition, and support. The surveys also included an examination of the occupational hygiene aspects of LNG use.

  14. Finite-momentum superfluidity and phase transitions in a p-wave resonant Bose gas

    SciTech Connect

    Choi, Sungsoo; Radzihovsky, Leo

    2011-10-15

    We study a degenerate two-species gas of bosonic atoms interacting through a p-wave Feshbach resonance as, for example, realized in a {sup 85}Rb-{sup 87}Rb mixture. We show that, in addition to a conventional atomic and a p-wave molecular spinor-1 superfluidity at large positive and negative detunings, respectively, the system generically exhibits a finite-momentum atomic-molecular superfluidity at intermediate detuning around the unitary point. We analyze the detailed nature of the corresponding phases and the associated quantum and thermal phase transitions.

  15. Liquid-gas phase transitions and C K symmetry in quantum field theories

    NASA Astrophysics Data System (ADS)

    Nishimura, Hiromichi; Ogilvie, Michael C.; Pangeni, Kamal

    2017-04-01

    A general field-theoretic framework for the treatment of liquid-gas phase transitions is developed. Starting from a fundamental four-dimensional field theory at nonzero temperature and density, an effective three-dimensional field theory is derived. The effective field theory has a sign problem at finite density. Although finite density explicitly breaks charge conjugation C , there remains a symmetry under C K , where K is complex conjugation. We consider four models: relativistic fermions, nonrelativistic fermions, static fermions and classical particles. The interactions are via an attractive potential due to scalar field exchange and a repulsive potential due to massive vector exchange. The field-theoretic representation of the partition function is closely related to the equivalence of the sine-Gordon field theory with a classical gas. The thermodynamic behavior is extracted from C K -symmetric complex saddle points of the effective field theory at tree level. In the cases of nonrelativistic fermions and classical particles, we find complex saddle point solutions but no first-order transitions, and neither model has a ground state at tree level. The relativistic and static fermions show a liquid-gas transition at tree level in the effective field theory. The liquid-gas transition, when it occurs, manifests as a first-order line at low temperature and high density, terminated by a critical end point. The mass matrix controlling the behavior of correlation functions is obtained from fluctuations around the saddle points. Due to the C K symmetry of the models, the eigenvalues of the mass matrix are not always real but can be complex. This leads to the existence of disorder lines, which mark the boundaries where the eigenvalues go from purely real to complex. The regions where the mass matrix eigenvalues are complex are associated with the critical line. In the case of static fermions, a powerful duality between particles and holes allows for the analytic

  16. Liquid-gas phase transitions and CK symmetry in quantum field theories

    DOE PAGES

    Nishimura, Hiromichi; Ogilvie, Michael C.; Pangeni, Kamal

    2017-04-04

    A general field-theoretic framework for the treatment of liquid-gas phase transitions is developed. Starting from a fundamental four-dimensional field theory at nonzero temperature and density, an effective three-dimensional field theory is derived. The effective field theory has a sign problem at finite density. Although finite density explicitly breaks charge conjugation C , there remains a symmetry under C K , where K is complex conjugation. Here, we consider four models: relativistic fermions, nonrelativistic fermions, static fermions and classical particles. The interactions are via an attractive potential due to scalar field exchange and a repulsive potential due to massive vector exchange.more » The field-theoretic representation of the partition function is closely related to the equivalence of the sine-Gordon field theory with a classical gas. The thermodynamic behavior is extracted from C K -symmetric complex saddle points of the effective field theory at tree level. In the cases of nonrelativistic fermions and classical particles, we find complex saddle point solutions but no first-order transitions, and neither model has a ground state at tree level. The relativistic and static fermions show a liquid-gas transition at tree level in the effective field theory. The liquid-gas transition, when it occurs, manifests as a first-order line at low temperature and high density, terminated by a critical end point. The mass matrix controlling the behavior of correlation functions is obtained from fluctuations around the saddle points. Due to the C K symmetry of the models, the eigenvalues of the mass matrix are not always real but can be complex. This then leads to the existence of disorder lines, which mark the boundaries where the eigenvalues go from purely real to complex. The regions where the mass matrix eigenvalues are complex are associated with the critical line. In the case of static fermions, a powerful duality between particles and holes allows for

  17. Molecular-scale remnants of the liquid-gas transition in supercritical polar fluids.

    PubMed

    Sokhan, V P; Jones, A; Cipcigan, F S; Crain, J; Martyna, G J

    2015-09-11

    An electronically coarse-grained model for water reveals a persistent vestige of the liquid-gas transition deep into the supercritical region. A crossover in the density dependence of the molecular dipole arises from the onset of nonpercolating hydrogen bonds. The crossover points coincide with the Widom line in the scaling region but extend farther, tracking the heat capacity maxima, offering evidence for liquidlike and gaslike state points in a "one-phase" fluid. The effect is present even in dipole-limit models, suggesting that it is common for all molecular liquids exhibiting dipole enhancement in the liquid phase.

  18. Influence of the glass transition on the liquid-gas spinodal decomposition.

    PubMed

    Testard, Vincent; Berthier, Ludovic; Kob, Walter

    2011-03-25

    We use large-scale molecular dynamics simulations to study the kinetics of the liquid-gas phase separation if the temperature is lowered across the glass transition of the dense phase. We observe a gradual change from phase separated systems at high temperatures to nonequilibrium, gel-like structures that evolve very slowly at low temperatures. The microscopic mechanisms responsible for the coarsening strongly depend on temperature, and change from diffusive motion at high temperature to a strongly intermittent, heterogeneous, and thermally activated dynamics at low temperature, leading to logarithmically slow growth of the typical domain size.

  19. Molecular-Scale Remnants of the Liquid-Gas Transition in Supercritical Polar Fluids

    NASA Astrophysics Data System (ADS)

    Sokhan, V. P.; Jones, A.; Cipcigan, F. S.; Crain, J.; Martyna, G. J.

    2015-09-01

    An electronically coarse-grained model for water reveals a persistent vestige of the liquid-gas transition deep into the supercritical region. A crossover in the density dependence of the molecular dipole arises from the onset of nonpercolating hydrogen bonds. The crossover points coincide with the Widom line in the scaling region but extend farther, tracking the heat capacity maxima, offering evidence for liquidlike and gaslike state points in a "one-phase" fluid. The effect is present even in dipole-limit models, suggesting that it is common for all molecular liquids exhibiting dipole enhancement in the liquid phase.

  20. Critical temperature for the nuclear liquid-gas phase transition (from multifragmentation and fission)

    SciTech Connect

    Karnaukhov, V. A.; Oeschler, H.; Budzanowski, A.; Avdeyev, S. P.; Botvina, A. S.; Cherepanov, E. A.; Karcz, W.; Kirakosyan, V. V.; Rukoyatkin, P. A.; Skwirczynska, I.; Norbeck, E.

    2008-12-15

    Critical temperature T{sub c} for the nuclear liquid-gas phase transition is estimated from both the multifragmentation and fission data. In the first case, the critical temperature is obtained by analysis of the intermediate-mass-fragment yields in p(8.1 GeV) + Au collisions within the statistical model of multifragmentation. In the second case, the experimental fission probability for excited {sup 188}Os is compared with the calculated one with T{sub c} as a free parameter. It is concluded for both cases that the critical temperature is higher than 15 MeV.

  1. Gas liquid flow at microgravity conditions - Flow patterns and their transitions

    NASA Astrophysics Data System (ADS)

    Dukler, A. E.; Fabre, J. A.; McQuillen, J. B.; Vernon, R.

    The prediction of flow patterns during gas-liquid flow in conduits is central to the modern approach for modeling two phase flow and heat transfer. The mechanisms of transition are reasonably well understood for flow in pipes on earth where it has been shown that body forces largely control the behavior observed. This work explores the patterns which exist under conditions of microgravity when these body forces are suppressed. Data are presented which were obtained for air-water flow in tubes during drop tower experiments and Learjet trajectories. Preliminary models to explain the observed flow pattern map are evolved.

  2. Gas liquid flow at microgravity conditions - Flow patterns and their transitions

    NASA Technical Reports Server (NTRS)

    Dukler, A. E.; Fabre, J. A.; Mcquillen, J. B.; Vernon, R.

    1987-01-01

    The prediction of flow patterns during gas-liquid flow in conduits is central to the modern approach for modeling two phase flow and heat transfer. The mechanisms of transition are reasonably well understood for flow in pipes on earth where it has been shown that body forces largely control the behavior observed. This work explores the patterns which exist under conditions of microgravity when these body forces are suppressed. Data are presented which were obtained for air-water flow in tubes during drop tower experiments and Learjet trajectories. Preliminary models to explain the observed flow pattern map are evolved.

  3. The use of inverse gas chromatography and gravimetric vapour sorption to study transitions in amorphous lactose.

    PubMed

    Ambarkhane, Ameet V; Pincott, Kim; Buckton, Graham

    2005-04-27

    The aim of this study was to measure the glass transition of amorphous lactose under well-controlled temperature and humidity, using inverse gas chromatography (IGC) and to relate these data to gravimetric vapour sorption experiments. Amorphous lactose (spray-dried) was exposed to a stepwise increment in the relative humidity (%RH) under isothermal conditions in an IGC. At the end of each conditioning step a decane injection was made, and the retention volumes were calculated using the maximum peak height (V(max)) method. The pressure drop across the column was recorded using the pressure transducers. These measurements were performed at various temperatures from 25 to 40 degrees C. The extent of water sorption at identical humidity (%RH) and temperature conditions was determined gravimetrically using dynamic vapour sorption (DVS). At each T, it was possible to determine: (1) a transition at low RH relating to the onset of mobility; (2) changes in retention volume relating to the point, where T(g) = T; (3) changes in pressure drop, which were related to the sample collapse. The rate and extent of water sorption was seen to alter at T(g) and also at a collapse point. Combinations of temperature and critical %RH (%cRH required to lower the dry glass transition temperature to the experimental temperature) obtained from IGC were comparable to those obtained from DVS. It was shown that at each T, the sample spontaneously crystallised, when T(g) was 32 degrees C below T. Inverse gas chromatograph can be used in this novel way to reveal the series of transitions that occur in amorphous materials.

  4. Phase transitions and damage spreading in a nonequilibrium lattice gas model with mixed dynamic rules

    NASA Astrophysics Data System (ADS)

    Rubio Puzzo, M. Leticia; Saracco, Gustavo P.; Bab, Marisa A.

    2016-02-01

    Phase transitions and damage spreading for a lattice gas model with mixed driven lattice gas (DLG)-Glauber dynamics are studied by means of Monte Carlo simulations. In order to control the number of sites updated according to the nonconservative Glauber dynamics, a parameter pɛ [ 0 , 1 ] is defined. In this way, for p = 0 the system corresponds to the DLG model with biased Kawasaki conservative dynamics, while for p = 1 it corresponds to the Ising model with Glauber dynamics. The results obtained show that the introduction of nonconservative dynamics dramatically affects the behavior of the DLG model, leading to the existence of Ising-like phase transitions from fully occupied to disordered states. The short-time dynamics results suggest that this transition is second order for values of p = 0.1 and p > 0.6 and first order for 0.1 < p ≤ 0.6. On the other hand, damage always spreads within the investigated temperature range and reaches a saturation value Dsat that depends on the system size, the temperature, and p. The value of Dsat in the thermodynamic limit is estimated by performing a finite-size analysis. For p < 0.6 the results show a change in the behavior of Dsat with temperature, similar to those reported for the pure (p = 0) DLG model. However, for p ≥ 0.6 the data remind us of the Ising (p = 1) curves. In each case, a damage temperature TD(p) can be defined as the value where either Dsat reaches a maximum or it becomes nonzero. This temperature is, within error bars, similar to the reported values of the temperatures that characterize the mentioned phase transitions.

  5. Polarization of the light from the 3P(1)-2S(1) transition in proton beam excited helium. Ph.D. Thesis; [target gas pressure effects

    NASA Technical Reports Server (NTRS)

    Weinhous, M. S.

    1973-01-01

    Measurements of the polarization of the light from the 3 1p-2 1s transition in proton beam excited Helium have shown both a proton beam energy and Helium target gas pressure dependence. Results for the linear polarization fraction range from +2.6% at 100 keV proton energy to -5.5% at 450 keV. The zero crossover occurs at approximately 225 keV. This is in good agreement with other experimental work in the field, but in poor agreement with theoretical predictions. Measurements at He target gas pressures as low as .01 mtorr show that the linear polarization fraction is still pressure dependent at .01 mtorr.

  6. Two-dimensional imaging of gas-to-particle transition in flames by laser-induced nanoplasmas

    SciTech Connect

    Zhang, Yiyang; Li, Shuiqing Ren, Yihua; Yao, Qiang; Law, Chung K.

    2014-01-13

    Two-dimensional imaging of gas/particle phase transition of metal oxides in their native high-temperature flow conditions, using laser-driven localized nanoplasmas, was obtained by utilizing the gap between the excitation energies of the gas and particle phases such that only the Ti atoms in the particle phase were selectively excited without detectable Bremsstrahlung background. These in situ images of the particle phase Ti distribution allow the quantitative visualization of the transition of the gas precursors to the nanoparticle phase across the flame sheet as well as diffusion of the particle concentration in the post-flame zone.

  7. An experimental trace gas investigation of fluid transport and mixing in a circular-to-rectangular transition duct

    NASA Technical Reports Server (NTRS)

    Reichert, B. A.; Hingst, W. R.; Okiishi, T. H.

    1991-01-01

    An ethylene trace gas technique was used to map out fluid transport and mixing within a circular to rectangular transition duct. Ethylene gas was injected at several points in a cross stream plane upstream of the transition duct. Ethylene concentration contours were determined at several cross stream measurement planes spaced axially within the duct. The flow involved a uniform inlet flow at a Mach number level of 0.5. Statistical analyses were used to quantitatively interpret the trace gas results. Also, trace gas data were considered along with aerodynamic and surface flow visualization results to ascertain transition duct flow phenomena. Convection of wall boundary layer fluid by vortices produced regions of high total pressure loss in the duct. The physical extent of these high loss regions is governed by turbulent diffusion.

  8. Effect of transition from slip to free molecular flow on gas transport in porous media

    NASA Astrophysics Data System (ADS)

    Bravo, Maria Cecilia

    2007-10-01

    Traditional models, such as the advection-diffusion and the dusty gas models, overlook the contribution of the transition flow regime between the slip and the free molecular flow, on the gas transport in porous media. In this work we demonstrate that, due to the existence of this intermediate regime, the Klinkenberg [Drill. & Prod. Prac. 1941, 200 (1941)] parameter b depends on the pressure. Reported experiments were used to corroborate such an effect and a formulation that extends the Klinkenberg equation—to include the effect of a region at pore scale where both molecule-molecule and molecule-wall interactions are important—was developed. The mathematical form of the extended Klinkenberg equation remains the same, but the slippage Klinkenberg's parameter b is now a generalized parameter that is a function of Knudsen's number. It was demonstrated that the widely accepted relation between the parameter b and the Knudsen diffusion coefficient is a good approximation just for Knudsen numbers corresponding to the free molecular flow regime. The model proposed in this paper reproduces the experimental data and predicts practical situations where important errors on total flow rate can be expected if the transition flow regime is neglected in the formalism.

  9. Ferromagnetic transition in harmonically trapped Fermi gas with higher partial-wave interactions

    NASA Astrophysics Data System (ADS)

    Sun, Zongli; Gu, Qiang

    2017-01-01

    Spontaneous ferromagnetic transition in trapped Fermi gas is studied in the presence of a higher partial-wave interaction. At the mean-field level, the ground-state energy contribution from an arbitrary partial wave is derived, with which the equilibrium density profile of each spin component can be calculated. Our results show that, in the spin-\\tfrac{1}{2} Fermi gas, the individual repulsive d-wave interaction can induce ferromagnetic transition; while the individual repulsive or attractive p- and f-wave interactions fail. In addition, the higher partial waves can have a remarkable influence on the ferromagnetic phase induced by the s-wave interaction. The repulsive d-wave interaction and attractive p- or f-wave interactions lower the s-wave Stoner point and critical particle number, while the attractive d-wave interaction and repulsive p- or f-wave interactions increase them. In addition, our results also show that both repulsive d-wave interaction and attractive p- or f-wave interactions can enhance the ferromagnetic state induced by s-wave interaction.

  10. Gas and dust hydrodynamical simulations of massive lopsided transition discs - II. Dust concentration

    NASA Astrophysics Data System (ADS)

    Baruteau, Clément; Zhu, Zhaohuan

    2016-06-01

    We investigate the dynamics of large dust grains in massive lopsided transition discs via 2D hydrodynamical simulations including both gas and dust. Our simulations adopt a ring-like gas density profile that becomes unstable against the Rossby-wave instability and forms a large crescent-shaped vortex. When gas self-gravity is discarded, but the indirect force from the displacement of the star by the vortex is included, we confirm that dust grains with stopping times of order the orbital time, which should be typically a few centimetres in size, are trapped ahead of the vortex in the azimuthal direction, while the smallest and largest grains concentrate towards the vortex centre. We obtain maximum shift angles of about 25°. Gas self-gravity accentuates the concentration differences between small and large grains. At low to moderate disc masses, the larger the grains, the farther they are trapped ahead of the vortex. Shift angles up to 90° are reached for 10 cm-sized grains, and we show that such large offsets can produce a double-peaked continuum emission observable at mm/cm wavelengths. This behaviour comes about because the large grains undergo horseshoe U-turns relative to the vortex due to the vortex's gravity. At large disc masses, since the vortex's pattern frequency becomes increasingly slower than Keplerian, small grains concentrate slightly beyond the vortex and large grains form generally non-axisymmetric ring-like structures around the vortex's radial location. Gas self-gravity therefore imparts distinct trapping locations for small and large dust grains, which may be probed by current and future observations.

  11. HAT-P-12b: A LOW-DENSITY SUB-SATURN MASS PLANET TRANSITING A METAL-POOR K DWARF

    SciTech Connect

    Hartman, J. D.; Bakos, G. A.; Torres, G.; Noyes, R. W.; Pal, A.; Latham, D. W.; Sipocz, B.; Esquerdo, G. A.; Sasselov, D. D.; Kovacs, Gabor; Stefanik, R. P.; Fernandez, J. M.; Kovacs, Geza; Fischer, D. A.; Johnson, J. A.; Marcy, G. W.; Howard, A. W.; Butler, R. P.; Lazar, J.; Papp, I.

    2009-11-20

    We report on the discovery of HAT-P-12b, a transiting extrasolar planet orbiting the moderately bright V approx 12.8 K4 dwarf GSC 03033 - 00706, with a period P = 3.2130598 +- 0.0000021 d, transit epoch T{sub c} = 2454419.19556 +- 0.00020 (BJD), and transit duration 0.0974 +- 0.0006 d. The host star has a mass of 0.73 +- 0.02 M{sub sun}, radius of 0.70{sup +0.02}{sub -0.01} R{sub sun}, effective temperature 4650 +- 60 K, and metallicity [Fe/H] = -0.29 +- 0.05. We find a slight correlation between the observed spectral line bisector spans and the radial velocity, so we consider, and rule out, various blend configurations including a blend with a background eclipsing binary, and hierarchical triple systems where the eclipsing body is a star or a planet. We conclude that a model consisting of a single star with a transiting planet best fits the observations, and show that a likely explanation for the apparent correlation is contamination from scattered moonlight. Based on this model, the planetary companion has a mass of 0.211 +- 0.012 M{sub J} and radius of 0.959{sup +0.029}{sub -0.021} R{sub J} yielding a mean density of 0.295 +- 0.025 g cm{sup -3}. Comparing these observations with recent theoretical models, we find that HAT-P-12b is consistent with a approx1-4.5 Gyr, mildly irradiated, H/He-dominated planet with a core mass M{sub C} approx< 10 M {sub +}. HAT-P-12b is thus the least massive H/He-dominated gas giant planet found to date. This record was previously held by Saturn.

  12. The warm gas atmosphere of the HD 100546 disk seen by Herschel. Evidence of a gas-rich, carbon-poor atmosphere?

    NASA Astrophysics Data System (ADS)

    Bruderer, S.; van Dishoeck, E. F.; Doty, S. D.; Herczeg, G. J.

    2012-05-01

    Context. With the Herschel Space Observatory, lines of simple molecules (C+, O, and high-J lines of CO, Jup ≳ 14) have been observed in the atmosphere of protoplanetary disks. When combined with ground-based data on [C i], all principle forms of carbon can be studied. These data allow us to test model predictions for the main carbon-bearing species and verify the presence of a warm surface layer. The absence of neutral carbon [C i], which is predicted by models to be strong, can then be interpreted together with ionized carbon [C ii] and carbon monoxide. Aims: We study the gas temperature, excitation, and chemical abundance of the simple carbon-bearing species C, C+, and CO, as well as O by the method of chemical-physical modeling. Using the models, we explore the sensitivity of the lines to the entering parameters and constrain the region from which the line radiation emerges. Methods: Numerical models of the radiative transfer in the lines and dust are used together with a chemical network simulation and a calculation of the gas energetics to obtain the gas temperature. We present our new model, which is based on our previous models but includes several improvements that we report in detail, together with the results of benchmark tests. Results: A model of the disk around the Herbig Be star HD 100546 is able to reproduce the CO ladder together with the atomic fine-structure lines of [O i] and either [C i] or [C ii]. We find that the high-J lines of CO can only be reproduced by a warm atmosphere with Tgas ≫ Tdust. The low-J lines of CO, observable from the ground, are dominated by the outer disk with a radius of several 100 AU, while the high-J CO observable with Herschel-PACS are dominated from regions within some tens of AU. The spectral profiles of high-J lines of CO are predicted to be broader than those of the low-J lines. We study the effect of several parameters including the size of the disk, the gas mass of the disk, the PAH abundance and distribution

  13. Coherent Control of Multiphoton Transitions in the Gas and Condensed Phases with Shaped Ultrashort Pulses

    SciTech Connect

    Marcos Dantus

    2008-09-23

    Controlling laser-molecule interactions has become an integral part of developing devices and applications in spectroscopy, microscopy, optical switching, micromachining and photochemistry. Coherent control of multiphoton transitions could bring a significant improvement of these methods. In microscopy, multi-photon transitions are used to activate different contrast agents and suppress background fluorescence; coherent control could generate selective probe excitation. In photochemistry, different dissociative states are accessed through two, three, or more photon transitions; coherent control could be used to select the reaction pathway and therefore the yield-specific products. For micromachining and processing a wide variety of materials, femtosecond lasers are now used routinely. Understanding the interactions between the intense femtosecond pulse and the material could lead to technologically important advances. Pulse shaping could then be used to optimize the desired outcome. The scope of our research program is to develop robust and efficient strategies to control nonlinear laser-matter interactions using ultrashort shaped pulses in gas and condensed phases. Our systematic research has led to significant developments in a number of areas relevant to the AMO Physics group at DOE, among them: generation of ultrashort phase shaped pulses, coherent control and manipulation of quantum mechanical states in gas and condensed phases, behavior of isolated molecules under intense laser fields, behavior of condensed phase matter under intense laser field and implications on micromachining with ultrashort pulses, coherent control of nanoparticles their surface plasmon waves and their nonlinear optical behavior, and observation of coherent Coulomb explosion processes at 10^16 W/cm^2. In all, the research has resulted in 36 publications (five journal covers) and nine invention disclosures, five of which have continued on to patenting

  14. Glass transition of adsorbed stereoregular PPMA by inverse gas chromatography at infinite dilution

    NASA Astrophysics Data System (ADS)

    Hamieh, T.; Rezzaki, M.; Grohens, Y.; Schultz, J.

    1998-10-01

    In this paper, we used inverse gas chromatography (IGC) at infinite dilution that proved to be a powerful technique to determine glass transition and other transitions of PMMA adsorbed on α-alumina. We highlighted the glass transition temperature of the system PMMA/α-Al2O3 with defined polymer tacticity at various covered surface fractions. Thus, the Tg of the adsorbed isotactic PMMA increases strongly as compared to the bulk value. The study of the physical chemical properties of PMMA/α-alumina revealed an important difference in the acidic and basic behaviour, in Lewis terms, of aluminium oxide covered by various concentrations of PMMA. It appears that there is a stabilisation of the physical chemical properties of PMMA/α-Al2O3 for a surface coverage above 50%. This study also highlighted an important effect of the tacticity of the polymer on the acid-base character of the system PMMA/Al2O3. Dans cet article, nous montrons que la chromatographie gazeuse inverse (CGI) à dilution infinie se révèle être une technique très intéressante pour la détermination de la transition vitreuse de polymères stéréoréguliers adsorbés sur des substrats solides tels que l'alumine. Nous avons mis en évidence des transitions attribuées aux phénomènes de relaxation béta, transition vitreuse et autres transitions des systèmes PMMA/Al2O3 de tacticité définie à différents taux de recouvrement. Ainsi, la Tg du PMMA isotactique adsorbé augmente de façon significative par rapport a celle du polymère massique. L'étude des propriétés physico-chimiques du système PMMA/Al2O3, révèle une différence importante dans le comportement acido-basique, au sens de Lewis, de l'alumine pour de taux de recouvrement en PMMA variables. Il apparaît qu'il y a stabilisation des propriétés physico-chimiques de PMMA/Al2O3 pour un taux de recouvrement en PMMA supérieur à 50 %. Cette étude a montré également une influence importante de la tacticité du polymère sur le

  15. In situ measurements of gas/particle-phase transitions for atmospheric semivolatile organic compounds

    PubMed Central

    Williams, Brent J.; Goldstein, Allen H.; Kreisberg, Nathan M.; Hering, Susanne V.

    2010-01-01

    An understanding of the gas/particle-phase partitioning of semivolatile compounds is critical in determining atmospheric aerosol formation processes and growth rates, which in turn affect global climate and human health. The Study of Organic Aerosol at Riverside 2005 campaign was performed to gain a better understanding of the factors responsible for aerosol formation and growth in Riverside, CA, a region with high concentrations of secondary organic aerosol formed through the phase transfer of low-volatility reaction products from the oxidation of precursor gases. We explore the ability of the thermal desorption aerosol gas chromatograph (TAG) to measure gas-to-particle-phase transitioning for several organic compound classes (polar and nonpolar) found in the ambient Riverside atmosphere by using in situ observations of several hundred semivolatile organic compounds. Here we compare TAG measurements to modeled partitioning of select semivolatile organic compounds. Although TAG was not designed to quantify the vapor phase of semivolatile organics, TAG measurements do distinguish when specific compounds are dominantly in the vapor phase, are dominantly in the particle phase, or have both phases present. Because the TAG data are both speciated and time-resolved, this distinction is sufficient to see the transition from vapor to particle phase as a function of carbon number and compound class. Laboratory studies typically measure the phase partitioning of semivolatile organic compounds by using pure compounds or simple mixtures, whereas hourly TAG phase partitioning measurements can be made in the complex mixture of thousands of polar/nonpolar and organic/inorganic compounds found in the atmosphere. PMID:20142511

  16. Relativistic coupled-cluster calculations of transition properties in highly charged inert-gas ions

    NASA Astrophysics Data System (ADS)

    Nandy, D. K.

    2016-11-01

    We have carried out an extensive investigation of various spectroscopic properties of highly charged inert-gas ions using a relativistic coupled-cluster method through a one-electron detachment procedure. In particular, we have calculated the atomic states 2 s22 p53/2 2P, 2 s22 p51/2 2P, and 2 s 2 p61/2 2S in F-like inert-gas ions; 3 s23 p53/2 2P, 3 s23 p51/2 2P, and 3 s 3 p61/2 2S states in Cl-like Kr, Xe, and Rn; and 4 s24 p53/2 2P, 4 s24 p51/2 2P, and 4 s 4 p61/2 2S states in Br-like Xe and Rn. Starting from a single-reference Dirac-Hartree-Fock wave function, we construct our exact atomic states by including the dynamic correlation effects in an all-order perturbative fashion. Employing this method, we estimate the ionization potential energies of three low-lying orbitals present in their respective closed-shell configurations. Since the considered highly charged inert-gas ions exhibit huge relativistic effects, we have taken into account the corrections due to Breit interaction as well as from the dominant quantum electrodynamic correction such as vacuum polarization and self-energy effects in these systems. Using our calculated relativistic atomic wave functions and energies, we accurately determine various transition properties such as wavelengths, line strengths, oscillator strengths, transition probabilities, and lifetimes of the excited states.

  17. Full-orbit atmospheric characterisation of a gas giant transiting an M dwarf

    NASA Astrophysics Data System (ADS)

    Triaud, Amaury; Gillon, Michael; Anderson, David R.; Maxted, Pierre; Ehrenreich, David; Heng, Kevin; Smith, Alexis M. S.; Queloz, Didier; Collier Cameron, Andrew; Hellier, Coel; Pollacco, Don

    2012-12-01

    The WASP (Wide Angle Search for Planets) consortium has identified a rare gas giant transiting a red dwarf. The combination of the size ratio and brightness contrast, along with the luminosity of the host star means that WASP-80b is one of the most practical target on which we can carry out an atmospheric characterisation. In addition, it gives us an opportunity to study a Jovian planet whose atmosphere is much less irradiated than the usual hot Jupiters. In order to confront theoretical predictions that have been made about heat redistribution and flux penetration in a temperature regime where they have not been tested yet, we aim to use the Spitzer Space telescope to observe and detect a full orbital phase curve. While its very deep transit is favourable to carry out transmission spectroscopy, the contrast between the planet and the star means we will have no issue detecting its emission spectrum. Our Spitzer observations mark the starting point of our campaign to characterise the atmosphere of a warm Jupiter which will lead to the construction of a full spectrum and a measure of its chemical abundances. This data will also be used to seek an additional transiting companion down to an inner Mars-sized planet.

  18. Mortality of urban transit workers: indications of an excess of deaths by suicide using gas.

    PubMed

    Guidotti, T L

    1992-08-01

    Urban bus drivers are exposed to a variety of discomforts and physical hazards associated with their occupation. We obtained death certificates for 99 per cent of 219 decreased members of the Amalgamated Transit Union Local 596 of Edmonton, Alberta, and conducted a proportionate mortality study against the distribution of all deaths among men in the province of Alberta, standardized by age and year of death. We found a highly significant excess from undetermined accidents due to gas (proportionate mortality ratio (PMR) 3761, based on 3 cases; p less than 0.003), which may bear a relationship to an elevation observed for suicide due to gas, which failed to achieve statistical significance (PMR 242, based on 2 cases). Collateral evidence suggests that this excess may include misclassification of some suicides. Gas inhalation as an instrument of suicide may be suggested by familiarity with vehicle exhaust. No other excess achieved statistical significance. Several causes of death showed elevated PMRs of relatively modest magnitude; elevations in PMR for lung cancer (PMR 154) and chronic obstructive pulmonary disease (PMR 176) suggest a mutual association with smoking.

  19. Transit time of electrons and gas gain effects in P-10 and Ar+CO2

    NASA Astrophysics Data System (ADS)

    Orchard, Gloria M.; Waker, Anthony J.

    2014-11-01

    An Electron Mobility Spectrometer (EMS) has been designed to measure the transit time and electron attachment effects in proportional counter fill gases. The aim of the EMS is to observe how electron parameters including the drift velocity, pulse formation time, multiplication gain and electron attachment depend on the gas composition and operating parameters of the EMS. The operating parameters of interest for the EMS include the applied high voltage and gas pressure. Current research interests include the measurement of the time between the generation of the electron-ion pairs and arrival of the electrons at the wire anode in P-10 and Ar+CO2 gases. Additionally, the study of the multiplication properties of the detector as a function of pulse formation time in the two gases and as a function of applied electric field will be presented. The overall objective of this work is to investigate if the gas-gain of a proportional counter can be optimized by minimizing electron attachment with oxygen to improve the measurement of tritium in air.

  20. Flow behaviour and transitions in surfactant-laden gas-liquid vertical flows

    NASA Astrophysics Data System (ADS)

    Zadrazil, Ivan; Chakraborty, Sourojeet; Matar, Omar; Markides, Christos

    2016-11-01

    The aim of this work is to elucidate the effect of surfactant additives on vertical gas-liquid counter-current pipe flows. Two experimental campaigns were undertaken, one with water and one with a light oil (Exxsol D80) as the liquid phase; in both cases air was used as the gaseous phase. Suitable surfactants were added to the liquid phase up to the critical micelle concentration (CMC); measurements in the absence of additives were also taken, for benchmarking. The experiments were performed in a 32-mm bore and 5-m long vertical pipe, over a range of superficial velocities (liquid: 1 to 7 m/s, gas: 1 to 44 m/s). High-speed axial- and side-view imaging was performed at different lengths along the pipe, together with pressure drop measurements. Flow regime maps were then obtained describing the observed flow behaviour and related phenomena, i.e., downwards/upwards annular flow, flooding, bridging, gas/liquid entrainment, oscillatory film flow, standing waves, climbing films, churn flow and dryout. Comparisons of the air-water and oil-water results will be presented and discussed, along with the role of the surfactants in affecting overall and detailed flow behaviour and transitions; in particular, a possible mechanism underlying the phenomenon of flooding will be presented. EPSRC UK Programme Grant EP/K003976/1.

  1. Gas holdup and flow regime transition in spider-sparger bubble column: effect of liquid phase properties

    NASA Astrophysics Data System (ADS)

    Besagni, G.; Inzoli, F.; De Guido, G.; Pellegrini, L. A.

    2017-01-01

    This paper discusses the effects of the liquid velocity and the liquid phase properties on the gas holdup and the flow regime transition in a large-diameter and large-scale counter-current two-phase bubble column. In particular, we compared and analysed the experimental data obtained in our previous experimental studies. The bubble column is 5.3 m in height, has an inner diameter of 0.24 m, it was operated with gas superficial velocities in the range of 0.004–0.20 m/s and, in the counter-current mode, the liquid was recirculated up to a superficial velocity of -0.09 m/s. Air was used as the dispersed phase and various fluids (tap water, aqueous solutions of sodium chloride, ethanol and monoethylene glycol) were employed as liquid phases. The experimental dataset consist in gas holdup measurements and was used to investigate the global fluid dynamics and the flow regime transition between the homogeneous flow regime and the transition flow regime. We found that the liquid velocity and the liquid phase properties significantly affect the gas holdup and the flow regime transition. In this respect, a possible relationship (based on the lift force) between the flow regime transition and the gas holdup was proposed.

  2. Transitions.

    ERIC Educational Resources Information Center

    Agnew, Jeanne L.; Choike, James R.

    1987-01-01

    Mathematical observations are made about some continuous curves, called transitions, encountered in well-known experiences. The transition parabola, the transition spiral, and the sidestep maneuver are presented. (MNS)

  3. Gas6 induces cancer cell migration and epithelial–mesenchymal transition through upregulation of MAPK and Slug

    SciTech Connect

    Lee, Yunhee; Lee, Mira; Kim, Semi

    2013-04-26

    Highlights: •We investigated the molecular mechanisms underlying Gas6-mediated cancer cell migration. •Gas6 treatment and subsequent Axl activation induce cell migration and EMT via upregulation of Slug. •Slug expression mediated by Gas6 is mainly through c-Jun and ATF-2 in an ERK1/2 and JNK-dependent manner. •The Gas6/Axl-Slug axis may be exploited as a target for anti-cancer metastasis therapy. -- Abstract: Binding of Gas6 to Axl (Gas6/Axl axis) alters cellular functions, including migration, invasion, proliferation, and survival. However, the molecular mechanisms underlying Gas6-mediated cell migration remain poorly understood. In this study, we found that Gas6 induced the activation of JNK and ERK1/2 signaling in cancer cells expressing Axl, resulting in the phosphorylation of activator protein-1 (AP-1) transcription factors c-Jun and ATF-2, and induction of Slug. Depletion of c-Jun or ATF-2 by siRNA attenuated the Gas6-induced expression of Slug. Slug expression was required for cell migration and E-cadherin reduction/vimentin induction induced by Gas6. These results suggest that Gas6 induced cell migration via Slug upregulation in JNK- and ERK1/2-dependent mechanisms. These data provide an important insight into the molecular mechanisms mediating Gas6-induced cell migration.

  4. Modelling flow pattern transitions for steady upward gas-liquid flow in vertical tubes. [Bubble, slug, churn and dispersed-annular; also existence regions and transitions

    SciTech Connect

    Taitel, Y.; Bornea, D.; Dukler, A.E.

    1980-05-01

    Models for predicting flow patterns in steady upward gas-liquid flow in vertical tubes (such as production-well tubing) delineate the transition boundaries between each of the four basic flow patterns for gas-liquid flow in vertical tubes: bubble, slug, churn, and dispersed-annular. Model results suggest that churn flow is the development region for the slug pattern and that bubble flow can exist in small pipes only at high liquid rates, where turbulent dispersion forces are high. Each transition depends on the flow-rate pair, fluid properties, and pipe size, but the nature of the dependence is different for each transition because of differing control mechanisms. The theoretical predictions are in reasonably good agreement with a variety of published flow maps based on experimental data.

  5. Long non-coding RNA CCAT2 is associated with poor prognosis in hepatocellular carcinoma and promotes tumor metastasis by regulating Snail2-mediated epithelial–mesenchymal transition

    PubMed Central

    Xu, Yongfu; Wang, Binfeng; Zhang, Fabiao; Wang, Aidong; Du, Xuefeng; Hu, Peng; Zhu, Yu; Fang, Zheping

    2017-01-01

    Increasing evidence has demonstrated that aberrant expressions of long non-coding RNAs (lncRNAs) are involved in various malignancies, including hepatocellular carcinoma (HCC). This study aimed to investigate the role of lncRNA colon cancer-associated transcript 2 (CCAT2) in the progression of HCC. Quantitative real-time polymerase chain reaction analysis confirmed that CCAT2 was upregulated in HCC cell lines and cancerous tissues compared with normal liver cell line and adjacent normal tissue samples. The level of CCAT2 was positively associated with tumor–node–metastasis stages and vessel invasion. Survival analyses revealed that high CCAT2 expression predicted poor prognostic outcomes, serving as an independent prognostic factor for HCC patients. Patients with high CCAT2 expression had a 1.849-fold increased risk of death compared with those with low CCAT2 expression. Moreover, we also found that knockdown of CCAT2 expression reduced cell migration and invasion in vitro. We further demonstrated that CCAT2 played a key role in enhancing the epithelial–mesenchymal transition (EMT) through the regulation of vimentin, E-cadherin and transcription factor snail2 expression. Taken together, our findings showed that high CCAT2 expression is associated with poor survival in HCC patients. CCAT2 promotes HCC progression by regulating Snail2-induced EMT. CCAT2 may be a prognostic biomarker and therapeutic target for HCC. PMID:28280353

  6. Gas content of transitional disks: a VLT/X-Shooter study of accretion and winds

    NASA Astrophysics Data System (ADS)

    Manara, C. F.; Testi, L.; Natta, A.; Rosotti, G.; Benisty, M.; Ercolano, B.; Ricci, L.

    2014-08-01

    Context. Transitional disks are thought to be a late evolutionary stage of protoplanetary disks whose inner regions have been depleted of dust. The mechanism responsible for this depletion is still under debate. To constrain the various models it is mandatory to have a good understanding of the properties of the gas content in the inner part of the disk. Aims: Using X-Shooter broad band - UV to near-infrared - medium-resolution spectroscopy, we derive the stellar, accretion, and wind properties of a sample of 22 transitional disks. The analysis of these properties allows us to place strong constraints on the gas content in a region very close to the star (≲0.2 AU) that is not accessible with any other observational technique. Methods: We fitted the spectra with a self-consistent procedure to simultaneously derive spectral type, extinction, and accretion properties of the targets. From the continuum excess at near-infrared wavelength we distinguished whether our targets have dust free inner holes. By analyzing forbidden emission lines, we derived the wind properties of the targets. We then compared our findings with results for classical T Tauri stars. Results: The accretion rates and wind properties of 80% of the transitional disks in our sample, which is strongly biased toward stongly accreting objects, are comparable to those of classical T Tauri stars. Thus, there are (at least) some transitional disks with accretion properties compatible with those of classical T Tauri stars, irrespective of the size of the dust inner hole. Only in two cases are the mass accretion rates much lower, while the wind properties remain similar. We detected no strong trend of the mass accretion rates with the size of the dust-depleted cavity or with the presence of a dusty optically thick disk very close to the star. These results suggest that, close to the central star, there is a gas-rich inner disk with a density similar to that of classical T Tauri star disks. Conclusions: The

  7. Self-consistent calculations of rare-gas-transition-metal interaction potentials

    NASA Astrophysics Data System (ADS)

    Drakova, D.; Doyen, G.; v. Trentini, F.

    1985-11-01

    A model Hamiltonian is used to calculate potential-energy surfaces for He and Ne on the (110) faces of Ni, Cu, Pd, and Ag. The calculations are nonperturbative, self-consistent, and contain no parameters which are fittable with respect to the gas-solid interaction. Static image-force effects are included. The theory represents the first quantum-mechanical approach to rare-gas-transition-metal potentials which includes the interaction of the rare-gas orbitals with the d electrons in a consistent way. Corrugation is found to be approximately proportional to the d-electron charge density. The sp band is represented by a Sommerfeld model with hybridization gap, which does not contribute to the corrugation. Part of the potential arises through the hybridization of the rare-gas orbitals with the unoccupied metal states. This interference energy is roughly a factor of 2 larger for neon than for helium, leading to larger corrugations of the neon potentials as compared with the helium potentials. This is in agreement with recent experiments, but in contrast to earlier theoretical predictions. The theoretically calculated corrugations and well depths compare reasonably to the experimental data where available. The computed values of corrugation for He increase in the order Ni, Cu, Ag, and Pd. This agrees with experiments where soft potentials have been fitted to the scattering data, although the predicted He/Ni(110) corrugation is overly large by more than a factor of 2. With increasing energy, the He corrugation increases slightly in the calculations. The dependence is nearly constant for Ni and strongest for Pd. For Ne/Ni(110) and Ne/Pd(110) corrugation decreases with energy. Image-force effects are found to be important for the corrugation and softness of the neon potentials.

  8. MUSE searches for galaxies near very metal-poor gas clouds at z ˜ 3: new constraints for cold accretion models

    NASA Astrophysics Data System (ADS)

    Fumagalli, Michele; Cantalupo, Sebastiano; Dekel, Avishai; Morris, Simon L.; O'Meara, John M.; Prochaska, J. Xavier; Theuns, Tom

    2016-10-01

    We report on the search for galaxies in the proximity of two very metal-poor gas clouds at z ˜ 3 towards the quasar Q0956+122. With a 5-hour Multi-Unit Spectroscopic Explorer (MUSE) integration in a ˜500 × 500 kpc2 region centred at the quasar position, we achieve a ≥80 per cent complete spectroscopic survey of continuum-detected galaxies with mR ≤ 25 mag and Lyα emitters with luminosity LLyα ≥ 3 × 1041 erg s- 1. We do not identify galaxies at the redshift of a z ˜ 3.2 Lyman limit system (LLS) with log Z/Z⊙ = -3.35 ± 0.05, placing this gas cloud in the intergalactic medium or circumgalactic medium of a galaxy below our sensitivity limits. Conversely, we detect five Lyα emitters at the redshift of a pristine z ˜ 3.1 LLS with log Z/Z⊙ ≤ -3.8, while ˜0.4 sources were expected given the z ˜ 3 Lyα luminosity function. Both this high detection rate and the fact that at least three emitters appear aligned in projection with the LLS suggest that this pristine cloud is tracing a gas filament that is feeding one or multiple galaxies. Our observations uncover two different environments for metal-poor LLSs, implying a complex link between these absorbers and galaxy haloes, which ongoing MUSE surveys will soon explore in detail. Moreover, in agreement with recent MUSE observations, we detected a ˜ 90 kpc Lyα nebula at the quasar redshift and three Lyα emitters reminiscent of a `dark galaxy' population.

  9. Transitions.

    ERIC Educational Resources Information Center

    Nathanson, Jeanne H., Ed.

    1993-01-01

    This theme issue on transitions for individuals with disabilities contains nine papers discussing transition programs and issues. "Transition Issues for the 1990s," by Michael J. Ward and William D. Halloran, discusses self-determination, school responsibility for transition, continued educational engagement of at-risk students, and service…

  10. A high-porosity limit for the transition from conductive to convective burning in gas-permeable explosives

    SciTech Connect

    Kagan, Leonid; Sivashinsky, Gregory

    2010-02-15

    The experimentally known phenomenon of an abrupt transition from slow conductive to fast convective (penetrative) burning in a confined gas-permeable explosive is discussed. A simple model, involving only the most essential physical ingredients, is formulated and analyzed. In addition to commonly utilized assumptions of the solid-gas thermal equilibrium, validity of Darcy's law, immobility of the solid phase, and one-step Arrhenius kinetics, the model employs the distinguished limit combining high-porosity with high solid/gas density ratio, resulting in conservation of enthalpy, advantageous for theoretical analysis. A good qualitative agreement between theoretical and experimental dependencies is obtained. The transition is triggered by a localized autoignition in the extended resistance-induced preheat zone formed ahead of the advancing deflagration, provided the pressure difference between hot gas products and gases deep inside the pores of the unburned solid exceeds a certain critical level. In line with observations the critical overpressure increases with diminishing permeability. (author)

  11. Critical dynamics of the jamming transition in one-dimensional nonequilibrium lattice-gas models.

    PubMed

    Priyanka; Jain, Kavita

    2016-04-01

    We consider several one-dimensional driven lattice-gas models that show a phase transition in the stationary state between a high-density fluid phase in which the typical length of a hole cluster is of order unity and a low-density jammed phase where a hole cluster of macroscopic length forms in front of a particle. Using a hydrodynamic equation for an interface growth model obtained from the driven lattice-gas models of interest here, we find that in the fluid phase, the roughness exponent and the dynamic exponent that, respectively, characterize the scaling of the saturation width and the relaxation time of the interface with the system size are given by the Kardar-Parisi-Zhang exponents. However, at the critical point, we show analytically that when the equal-time density-density correlation function decays slower than inverse distance, the roughness exponent varies continuously with a parameter in the hop rates, but it is one-half otherwise. Using these results and numerical simulations for the density-density autocorrelation function, we further find that the dynamic exponent z=3/2 in all cases.

  12. Study of the spray to globular transition in gas metal arc welding: a spectroscopic investigation

    NASA Astrophysics Data System (ADS)

    Valensi, F.; Pellerin, S.; Castillon, Q.; Boutaghane, A.; Dzierzega, K.; Zielinska, S.; Pellerin, N.; Briand, F.

    2013-06-01

    The gas metal arc welding (GMAW) process is strongly influenced by the composition of the shielding gas. In particular, addition of CO2 increases the threshold current for the transition from unstable globular to more stable spray transfer mode. We report on the diagnostics—using optical emission spectroscopy—of a GMAW plasma in pure argon and in mixtures of argon, CO2 and N2 while operated in spray and globular transfer modes. The spatially resolved plasma parameters are obtained by applying the Abel transformation to laterally integrated emission data. The Stark widths of some iron lines are used to determine both electron density and temperature, and line intensities yield relative contents of neutral and ionized iron to argon. Our experimental results indicate a temperature drop on the arc axis in the case of spray arc transfer. This drop reduces with addition of N2 and disappears in globular transfer mode when CO2 is added. Despite the temperature increase, the electron density decreases with CO2 concentration. The highest concentration of iron is observed in the plasma column upper part (close to the anode) and for GMAW with CO2. Our results are compared with recently published works where the effect of non-homogeneous metal vapour concentration has been taken into account.

  13. Transition from gas to plasma kinetic equilibria in gravitating axisymmetric structures

    SciTech Connect

    Cremaschini, Claudio; Stuchlík, Zdeněk

    2014-04-15

    The problem of the transition from gas to plasma in gravitating axisymmetric structures is addressed under the assumption of having initial and final states realized by kinetic Maxwellian-like equilibria. In astrophysics, the theory applies to accretion-disc scenarios around compact objects. A formulation based on non-relativistic kinetic theory for collisionless systems is adopted. Equilibrium solutions for the kinetic distribution functions describing the initial neutral matter and the resulting plasma state are constructed in terms of single-particle invariants and expressed by generalized Maxwellian distributions. The final plasma configuration is related to the initial gas distribution by the introduction of appropriate functional constraints. Qualitative aspects of the solution are investigated and physical properties of the system are pointed out. In particular, the admitted functional dependences of the fluid fields carried by the corresponding equilibrium distributions are determined. Then, the plasma is proved to violate the condition of quasi-neutrality, implying a net charge separation between ions and electrons. This result is shown to be independent of the precise realization of the plasma distribution function, while a physical mechanism able to support a non-neutral equilibrium state is proposed.

  14. Theory of femtosecond coherent anti-Stokes Raman scattering spectroscopy of gas-phase transitions.

    PubMed

    Lucht, Robert P; Kinnius, Paul J; Roy, Sukesh; Gord, James R

    2007-07-28

    A theoretical analysis of coherent anti-Stokes Raman scattering (CARS) spectroscopy of gas-phase resonances using femtosecond lasers is performed. The time-dependent density matrix equations for the femtosecond CARS process are formulated and manipulated into a form suitable for solution by direct numerical integration (DNI). The temporal shapes of the pump, Stokes, and probe laser pulses are specified as an input to the DNI calculations. It is assumed that the laser pulse shapes are 70 fs Gaussians and that the pulses are Fourier-transform limited. A single excited electronic level is defined as an effective intermediate level in the Raman process, and transition strengths are adjusted to match the experimental Raman polarizability. The excitation of the Raman coherence is investigated for different Q-branch rotational transitions in the fundamental 2330 cm(-1) band of diatomic nitrogen, assuming that the pump and Stokes pulses are temporally overlapped. The excitation process is shown to be virtually identical for transitions ranging from Q2 to Q20. The excitation of the Raman coherences is also very efficient; for laser irradiances of 5x10(17) W/m2, corresponding approximately to a 100 microJ, 70 fs pulse focused to 50 microm, approximately 10% of the population of the ground Raman level is pumped to the excited Raman level during the impulsive pump-Stokes excitation, and the magnitude of the induced Raman coherence reaches 40% of its maximum possible value. The theoretical results are compared with the results of experiments where the femtosecond CARS signal is recorded as a function of probe delay with respect to the impulsive pump-Stokes excitation.

  15. Residual Gas and Dust around Transition Objects and Weak T Tauri Stars

    NASA Astrophysics Data System (ADS)

    Doppmann, Greg W.; Najita, Joan R.; Carr, John S.

    2017-02-01

    Residual gas in disks around young stars can spin down stars, circularize the orbits of terrestrial planets, and whisk away the dusty debris that is expected to serve as a signpost of terrestrial planet formation. We have carried out a sensitive search for residual gas and dust in the terrestrial planet region surrounding young stars ranging in age from a few to ˜10 Myr. Using high-resolution 4.7 μm spectra of transition objects (TOs) and weak T Tauri stars, we searched for weak continuum excesses and CO fundamental emission, after making a careful correction for the stellar contribution to the observed spectrum. We find that the CO emission from TOs is weaker and located farther from the star than CO emission from nontransition T Tauri stars with similar stellar accretion rates. The difference is possibly the result of chemical and/or dynamical effects (i.e., a low CO abundance or close-in low-mass planets). The weak T Tauri stars show no CO fundamental emission down to low flux levels (5 × 10-20 to 10-18 W m-2). We illustrate how our results can be used to constrain the residual disk gas content in these systems and discuss their potential implications for star and planet formation. Data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency’s scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  16. Unregulated emissions from compressed natural gas (CNG) transit buses configured with and without oxidation catalyst.

    PubMed

    Okamoto, Robert A; Kado, Norman Y; Kuzmicky, Paul A; Ayala, Alberto; Kobayashi, Reiko

    2006-01-01

    The unregulated emissions from two in-use heavy-duty transit buses fueled by compressed natural gas (CNG) and equipped with oxidation catalyst (OxiCat) control were evaluated. We tested emissions from a transit bus powered by a 2001 Cummins Westport C Gas Plus 8.3-L engine (CWest), which meets the California Air Resources Board's (CARB) 2002 optional NOx standard (2.0 g/bhp-hr). In California, this engine is certified only with an OxiCat, so our study did not include emissions testing without it. We also tested a 2000 New Flyer 40-passenger low-floor bus powered by a Detroit Diesel series 50G engine (DDCs50G) that is currently certified in California without an OxiCat. The original equipment manufacturer (OEM) offers a "low-emission" package for this bus that includes an OxiCat for transit bus applications, thus, this configuration was also tested in this study. Previously, we reported that formaldehyde and other volatile organic emissions detected in the exhaust of the DDCs50G bus equipped with an OxiCat were significantly reduced relative to the same DDCs50G bus without OxiCat. In this paper, we examine othertoxic unregulated emissions of significance. The specific mutagenic activity of emission sample extracts was examined using the microsuspension assay. The total mutagenic activity of emissions (activity per mile) from the OxiCat-equipped DDC bus was generally lower than that from the DDC bus without the OxiCat. The CWest bus emission samples had mutagenic activity that was comparable to that of the OxiCat-equipped DDC bus. In general, polycyclic aromatic hydrocarbon (PAH) emissions were lower forthe OxiCat-equipped buses, with greater reductions observed for the volatile and semivolatile PAH emissions. Elemental carbon (EC) was detected in the exhaust from the all three bus configurations, and we found that the total carbon (TC) composition of particulate matter (PM) emissions was primarily organic carbon (OC). The amount of carbon emissions far exceeded the

  17. KELT-6b: A P ∼ 7.9 day hot Saturn transiting a metal-poor star with a long-period companion

    SciTech Connect

    Collins, Karen A.; Kielkopf, John F.; Eastman, Jason D.; Beatty, Thomas G.; Gaudi, B. Scott; Siverd, Robert J.; Pepper, Joshua; Stassun, Keivan G.; Johnson, John Asher; Howard, Andrew W.; Fulton, Benjamin J.; Fischer, Debra A.; Manner, Mark; Bieryla, Allyson; Latham, David W.; Gregorio, Joao; Buchhave, Lars A.; Jensen, Eric L. N.; Penev, Kaloyan; Crepp, Justin R.; and others

    2014-02-01

    We report the discovery of KELT-6b, a mildly inflated Saturn-mass planet transiting a metal-poor host. The initial transit signal was identified in KELT-North survey data, and the planetary nature of the occulter was established using a combination of follow-up photometry, high-resolution imaging, high-resolution spectroscopy, and precise radial velocity measurements. The fiducial model from a global analysis including constraints from isochrones indicates that the V = 10.38 host star (BD+31 2447) is a mildly evolved, late-F star with T {sub eff} = 6102 ± 43 K, log g{sub ⋆}=4.07{sub −0.07}{sup +0.04}, and [Fe/H] = –0.28 ± 0.04, with an inferred mass M {sub *} = 1.09 ± 0.04 M {sub ☉} and radius R{sub ⋆}=1.58{sub −0.09}{sup +0.16} R{sub ⊙}. The planetary companion has mass M{sub P} = 0.43 ± 0.05 M {sub Jup}, radius R{sub P}=1.19{sub −0.08}{sup +0.13} R{sub Jup}, surface gravity log g{sub P}=2.86{sub −0.08}{sup +0.06}, and density ρ{sub P}=0.31{sub −0.08}{sup +0.07} g cm{sup −3}. The planet is on an orbit with semimajor axis a = 0.079 ± 0.001 AU and eccentricity e=0.22{sub −0.10}{sup +0.12}, which is roughly consistent with circular, and has ephemeris of T {sub c}(BJD{sub TDB}) = 2456347.79679 ± 0.00036 and P = 7.845631 ± 0.000046 days. Equally plausible fits that employ empirical constraints on the host-star parameters rather than isochrones yield a larger planet mass and radius by ∼4)-7). KELT-6b has surface gravity and incident flux similar to HD 209458b, but orbits a host that is more metal poor than HD 209458 by ∼0.3 dex. Thus, the KELT-6 system offers an opportunity to perform a comparative measurement of two similar planets in similar environments around stars of very different metallicities. The precise radial velocity data also reveal an acceleration indicative of a longer-period third body in the system, although the companion is not detected in Keck adaptive optics images.

  18. KELT-6b: A P ~ 7.9 Day Hot Saturn Transiting a Metal-poor Star with a Long-period Companion

    NASA Astrophysics Data System (ADS)

    Collins, Karen A.; Eastman, Jason D.; Beatty, Thomas G.; Siverd, Robert J.; Gaudi, B. Scott; Pepper, Joshua; Kielkopf, John F.; Johnson, John Asher; Howard, Andrew W.; Fischer, Debra A.; Manner, Mark; Bieryla, Allyson; Latham, David W.; Fulton, Benjamin J.; Gregorio, Joao; Buchhave, Lars A.; Jensen, Eric L. N.; Stassun, Keivan G.; Penev, Kaloyan; Crepp, Justin R.; Hinkley, Sasha; Street, Rachel A.; Cargile, Phillip; Mack, Claude E.; Oberst, Thomas E.; Avril, Ryan L.; Mellon, Samuel N.; McLeod, Kim K.; Penny, Matthew T.; Stefanik, Robert P.; Berlind, Perry; Calkins, Michael L.; Mao, Qingqing; Richert, Alexander J. W.; DePoy, Darren L.; Esquerdo, Gilbert A.; Gould, Andrew; Marshall, Jennifer L.; Oelkers, Ryan J.; Pogge, Richard W.; Trueblood, Mark; Trueblood, Patricia

    2014-02-01

    We report the discovery of KELT-6b, a mildly inflated Saturn-mass planet transiting a metal-poor host. The initial transit signal was identified in KELT-North survey data, and the planetary nature of the occulter was established using a combination of follow-up photometry, high-resolution imaging, high-resolution spectroscopy, and precise radial velocity measurements. The fiducial model from a global analysis including constraints from isochrones indicates that the V = 10.38 host star (BD+31 2447) is a mildly evolved, late-F star with T eff = 6102 ± 43 K, log g_\\star =4.07_{-0.07}^{+0.04}, and [Fe/H] = -0.28 ± 0.04, with an inferred mass M sstarf = 1.09 ± 0.04 M ⊙ and radius R_\\star =1.58_{-0.09}^{+0.16} \\,R_\\odot. The planetary companion has mass MP = 0.43 ± 0.05 M Jup, radius R_{P}=1.19_{-0.08}^{+0.13} \\,R_Jup, surface gravity log g_{P}=2.86_{-0.08}^{+0.06}, and density \\rho _{P}=0.31_{-0.08}^{+0.07}\\,g\\,cm^{-3}. The planet is on an orbit with semimajor axis a = 0.079 ± 0.001 AU and eccentricity e=0.22_{-0.10}^{+0.12}, which is roughly consistent with circular, and has ephemeris of T c(BJDTDB) = 2456347.79679 ± 0.00036 and P = 7.845631 ± 0.000046 days. Equally plausible fits that employ empirical constraints on the host-star parameters rather than isochrones yield a larger planet mass and radius by ~4}-7}. KELT-6b has surface gravity and incident flux similar to HD 209458b, but orbits a host that is more metal poor than HD 209458 by ~0.3 dex. Thus, the KELT-6 system offers an opportunity to perform a comparative measurement of two similar planets in similar environments around stars of very different metallicities. The precise radial velocity data also reveal an acceleration indicative of a longer-period third body in the system, although the companion is not detected in Keck adaptive optics images. KELT is a joint project of The Ohio State University, Vanderbilt University, and Lehigh University.

  19. Transitions.

    ERIC Educational Resources Information Center

    Field, David; And Others

    1992-01-01

    Includes four articles: "Career Aspirations" (Field); "Making the Transition to a New Curriculum" (Baker, Householder); "How about a 'Work to School' Transition?" (Glasberg); and "Technological Improvisation: Bringing CNC to Woodworking" (Charles, McDuffie). (SK)

  20. Methodology Development of a Gas-Liquid Dynamic Flow Regime Transition Model

    NASA Astrophysics Data System (ADS)

    Doup, Benjamin Casey

    Current reactor safety analysis codes, such as RELAP5, TRACE, and CATHARE, use flow regime maps or flow regime transition criteria that were developed for static fully-developed two-phase flows to choose interfacial transfer models that are necessary to solve the two-fluid model. The flow regime is therefore difficult to identify near the flow regime transitions, in developing two-phase flows, and in transient two-phase flows. Interfacial area transport equations were developed to more accurately predict the dynamic nature of two-phase flows. However, other model coefficients are still flow regime dependent. Therefore, an accurate prediction of the flow regime is still important. In the current work, the methodology for the development of a dynamic flow regime transition model that uses the void fraction and interfacial area concentration obtained by solving three-field the two-fluid model and two-group interfacial area transport equation is investigated. To develop this model, detailed local experimental data are obtained, the two-group interfacial area transport equations are revised, and a dynamic flow regime transition model is evaluated using a computational fluid dynamics model. Local experimental data is acquired for 63 different flow conditions in bubbly, cap-bubbly, slug, and churn-turbulent flow regimes. The measured parameters are the group-1 and group-2 bubble number frequency, void fraction, interfacial area concentration, and interfacial bubble velocities. The measurements are benchmarked by comparing the prediction of the superficial gas velocities, determined using the local measurements with those determined from volumetric flow rate measurements and the agreement is generally within +/-20%. The repeatability four-sensor probe construction process is within +/-10%. The repeatability of the measurement process is within +/-7%. The symmetry of the test section is examined and the average agreement is within +/-5.3% at z/D = 10 and +/-3.4% at z/D = 32

  1. Poor Sleep Habits = Poor Grades

    MedlinePlus

    ... https://medlineplus.gov/news/fullstory_166509.html Poor Sleep Habits = Poor Grades Study of college students finds ... socialize, college life seems geared toward an erratic sleep schedule. But new research suggests that an unpredictable ...

  2. Freeze-out temperature and density in heavy-ion collisions at liquid-gas phase transition

    SciTech Connect

    Shlomo, Shalom

    2010-08-04

    The study of properties of hot nuclei and the search for liquid-gas phase transition in nuclei have been the subjects of many investigations in recent decades. We present a short and limited review of the theoretical and experimental status of determining the temperature and density of the disassembling nucleus from ratios of the yields of emitted fragments.

  3. Over-Expressed Twist Associates with Markers of Epithelial Mesenchymal Transition and Predicts Poor Prognosis in Breast Cancers via ERK and Akt Activation

    PubMed Central

    Liang, Yuan-Ke; Chen, Wei-Ling; Zhang, Fan; Bai, Jing-Wen; Qiu, Si-Qi; Du, Cai-Wen; Huang, Wen-He; Zhang, Guo-Jun

    2015-01-01

    Overexpression of Twist, a highly conserved basic helix-loop-helix transcription factor, is associated with epithelial-mesenchymal transition (EMT) and predicts poor prognosis in various kinds of cancers, including breast cancer. In order to further clarify Twist’s role in breast cancer, we detected Twist expression in breast cancer tissues by immunohistochemistry. Twist expression was observed in 54% (220/408) of breast cancer patients and was positively associated with tumor size, Ki67, VEGF-C and HER2 expression. Conversely, Twist was negatively associated with estrogen receptor (ER), progesterone receptor (PgR) and E-cadherin expression. Patients with Twist expression had a poorer prognosis for 30-month disease free survival (DFS) (82.9%) than patients with negative Twist (92.3%). Overexpression of Twist led to dramatic changes in cellular morphology, proliferation, migratory/invasive capability, and expression of EMT-related biomarkers in breast cancer cells. Moreover, we show that Twist serves as a driver of tumorigenesis, as well as an inducer of EMT, at least in part, through activation of the Akt and extracellular signal-regulated protein kinase (ERK) pathways which are critical for Twist-mediated EMT. Our results demonstrate that Twist expression is an important prognostic factor in breast cancer patients. PMID:26295469

  4. ADP-ribosylation factor 1 expression regulates epithelial-mesenchymal transition and predicts poor clinical outcome in triple-negative breast cancer

    PubMed Central

    Schlienger, Sabrina; Campbell, Shirley; Pasquin, Sarah; Gaboury, Louis; Claing, Audrey

    2016-01-01

    Metastatic capacities are fundamental features of tumor malignancy. ADP-ribosylation factor (ARF) 1 has emerged as a key regulator of invasion in breast cancer cells. However, the importance of this GTPase, in vivo, remains to be demonstrated. We report that ARF1 is highly expressed in breast tumors of the most aggressive and advanced subtypes. Furthermore, we show that lowered expression of ARF1 impairs growth of primary tumors and inhibits lung metastasis in a murine xenograft model. To understand how ARF1 contributes to invasiveness, we used a poorly invasive breast cancer cell line, MCF7 (ER+), and examined the effects of overexpressing ARF1 to levels similar to that found in invasive cell lines. We demonstrate that ARF1 overexpression leads to the epithelial-mesenchymal transition (EMT). Mechanistically, ARF1 controls cell–cell adhesion through ß-catenin and E-cadherin, oncogenic Ras activation and expression of EMT inducers. We further show that ARF1 overexpression enhances invasion, proliferation and resistance to a chemotherapeutic agent. In vivo, ARF1 overexpressing MCF7 cells are able to form more metastases to the lung. Overall, our findings demonstrate that ARF1 is a molecular switch for cancer progression and thus suggest that limiting the expression/activation of this GTPase could help improve outcome for breast cancer patients. PMID:26908458

  5. Transition metal catalysis in the generation of petroleum and natural gas. Final report, September 1, 1992--October 31, 1995

    SciTech Connect

    Mango, F.D.

    1997-01-21

    This project originated on the premise that natural gas could be formed catalytically in the earth rather than thermally as commonly believed. The intention was to test this hypothetical view and to explore generally the role of sedimentary metals in the generation of light hydrocarbons (C1 - C9). We showed the metalliferous source rocks are indeed catalytic in the generation of natural gas. Various metal compounds in the pure state show the same levels of catalytic activity as sedimentary rocks and the products are identical. Nickel is particularly active among the early transition metals and is projected to remain catalytically robust at all stages of catagenesis. Nickel oxide promotes the formation of n-alkanes in addition to natural gas (NG), demonstrating the full scope of the hypothetical catalytic process. The composition of catalytic gas duplicates the entire range of natural gas, from so-called wet gas to dry gas (60 to 95+ wt % methane), while gas generated thermally is consistently depleted in methane (10 to 60 wt % methane). These results support the view that metal catalysis is a major pathway through which natural gas is formed in the earth.

  6. Mid-section of a can-annular gas turbine engine with a cooling system for the transition

    DOEpatents

    Wiebe, David J.; Rodriguez, Jose L.

    2015-12-08

    A cooling system is provided for a transition (420) of a gas turbine engine (410). The cooling system includes a cowling (460) configured to receive an air flow (111) from an outlet of a compressor section of the gas turbine engine (410). The cowling (460) is positioned adjacent to a region of the transition (420) to cool the transition region upon circulation of the air flow within the cowling (460). The cooling system further includes a manifold (121) to directly couple the air flow (111) from the compressor section outlet to an inlet (462) of the cowling (460). The cowling (460) is configured to circulate the air flow (111) within an interior space (426) of the cowling (460) that extends radially outward from an inner diameter (423) of the cowling to an outer diameter (424) of the cowling at an outer surface.

  7. Long noncoding RNA GAS5 inhibits malignant proliferation and chemotherapy resistance to doxorubicin in bladder transitional cell carcinoma.

    PubMed

    Zhang, Hui; Guo, Yan; Song, Yongsheng; Shang, Chao

    2017-01-01

    Bladder cancer is the most general malignant cancer in genitourinary system, more than 90% of BCs are bladder transitional cell carcinomas (BTCC). This study aimed to investigate the clinical significance of growth arrest-specific 5 (GAS5) gene and its regulatory effects of malignant proliferation and chemotherapy resistance to doxorubicin in BTCC cells. The expression of GAS5 was detected by quantitative real-time PCR. Statistical analysis was used to determine the relationship between GAS5 expression and clinical features and the prognostic value of GAS5 for disease free survival. MTT assay was used to detect cell proliferation ability and chemosensitivity. Dual-color flow cytometric method was used to detect cell apoptosis. The expression of Bcl-2 protein was examined by western blot. In this study, we found that GAS5 low-expressed in BTCC tissues and cells, and its low expression level had positive correlation with higher pathological grades of BTCC. Moreover, GAS5 was a prognostic biomarker of disease free survival for BTCC patients. GAS5 over-expression could inhibit cell proliferation of BTCC J82 and T24 cells significantly. The IC50 to doxorubicin in T24/DOX cells (resistance to doxorubicin) presented a conspicuous depression, GAS5 enhancement reduced the chemotherapy resistance to doxorubicin. GAS5 over-expression promoted apoptosis induced by doxorubicin in T24/DOX cells, and depressed the expression of anti-apoptosis protein Bcl-2. The results indicated that GAS5 regulated the chemotherapy resistance to doxorubicin via Bcl2 partly. In summary, lncRNA GAS5 was a prognostic biomarker of disease free survival in BTCC patients, and acted as a tumor-suppressing gene to inhibit malignant proliferation and resistance to doxorubicin in BTCC cells. LncRNA GAS5 might be a novel potential therapeutic target for BTCC.

  8. A Multi-wavelength Analysis of Dust and Gas in the SR 24S Transition Disk

    NASA Astrophysics Data System (ADS)

    Pinilla, P.; Pérez, L. M.; Andrews, S.; van der Marel, N.; van Dishoeck, E. F.; Ataiee, S.; Benisty, M.; Birnstiel, T.; Juhász, A.; Natta, A.; Ricci, L.; Testi, L.

    2017-04-01

    We present new Atacama Large Millimeter/sub-millimeter Array (ALMA) 1.3 mm continuum observations of the SR 24S transition disk with an angular resolution ≲ 0\\buildrel{ \\prime}\\over{.} 18 (12 au radius). We perform a multi-wavelength investigation by combining new data with previous ALMA data at 0.45 mm. The visibilities and images of the continuum emission at the two wavelengths are well characterized by a ring-like emission. Visibility modeling finds that the ring-like emission is narrower at longer wavelengths, in good agreement with models of dust-trapping in pressure bumps, although there are complex residuals that suggest potentially asymmetric structures. The 0.45 mm emission has a shallower profile inside the central cavity than the 1.3 mm emission. In addition, we find that the 13CO and C18O (J = 2-1) emission peaks at the center of the continuum cavity. We do not detect either continuum or gas emission from the northern companion to this system (SR 24N), which is itself a binary system. The upper limit for the dust disk mass of SR 24N is ≲ 0.12 {M}\\bigoplus , which gives a disk mass ratio in dust between the two components of {M}{dust,{SR}24{{S}}}/{M}{dust,{SR}24{{N}}}≳ 840. The current ALMA observations may imply that either planets have already formed in the SR 24N disk or that dust growth to millimeter sizes is inhibited there and that only warm gas, as seen by rovibrational CO emission inside the truncation radii of the binary, is present.

  9. A Mass Spectrometry and DFT study of pyrithione complexes with transition metals in the gas phase.

    PubMed

    Butler, Matias; Cabrera, Gabriela M

    2017-07-24

    2-mercaptopyridine N-oxide (pyrithione, PTOH) along with several transition metal ions forms coordination compounds displaying notable biological activities. Gas-phase complexes formed between pyrithione and Manganese (II), Cobalt (II), Nickel (II), Copper (II) and Zinc (II) were investigated by infusion in the electrospray source of a quadrupole-time of flight mass spectrometer. Remarkably, positive ion mode spectra displayed the singly charged metal adduct ion [C10 H8 MN2 O2 S2 ](2+) ([M(PTO)2 ](+•) or [M(DPTO)](+•) ), where DPTO is dipyrithione, 2,2'-dithiobis(pyridine N-oxide), among the most abundant peaks, implying a change in the oxidation state of whether the metal ion or the ligands. In addition, doubly charged ions were recognized as metal adduct ions containing DPTO ligands, [M(DPTO)n ](2+) . Generation of [M(PTO)2 ](+•) / [M(DPTO)](+•) could be traced by CID of [M(DPTO)2 ](2+) , by observation of the sequential losses of a charged (PTO(+) ) and a radical (PTO(•) ) deprotonated pyrithione ligand. The fragmentation pathways of [M(PTO)2 ](+•) / [M(DPTO)](+•) were compared among the different metal ions, and some common features were noticed. Density functional theory (DFT) calculations were employed to study the structures of the observed adduct ions, and especially, to decide in the adduct ion [M(PTO)2 ](+•) / [M(DPTO)](+•) whether the ligands are two deprotonated pyrithiones or a single dipyrithione as well as the oxidation state of the metal ion in the complex. Characterization of gas-phase pyrithione metal ion complexes becomes important, especially taking into account the presence of a redox-active ligand in the complexes, since redox state changes that produce new species can have a marked effect on the overall toxicological/biological response elicited by the metal system. This article is protected by copyright. All rights reserved.

  10. Sediments overlying exhumed continental mantle: a proxy for the morphotectonic evolution of the Ocean Continent Transition in magma-poor rifted margins

    NASA Astrophysics Data System (ADS)

    Karpoff, A. M.; Manatschal, G.; Bernoulli, D.; Lagabrielle, Y.

    2003-04-01

    Observations from ancient and present-day magma-poor rifted margins in the Alps and Iberia provide compelling evidence that within the ocean-continent transition (OCT) crustal and sub-continental mantle rocks were exhumed along downward-concave faults which were active during final rifting and accommodated high amounts of extension. The faults are overlain by stranded allochthons of continental origin, pillow basalts, and pelagic sediments, i.e. radiolarites and/or pelagic limestones, and hemipelagic shales. Associated with the faults are tectono-sedimentary breccias and various types of clastic sediments, ranging from debris flow deposits to laminated sandstone, and quartz-rich silt- and claystones. Mineralogical studies of the shales, red jaspers, and red cherts overlying mantle rocks in the Alps of eastern Switzerland are typically quartz-rich and contain variable amounts of phyllosilicates (chlorite and/or mica), feldspars, ± calcite, oxides, pyrite, and epidote. Their main geochemical characteristic is the high silica and low iron and manganese content, which contrasts with that of "metalliferous" Fe-Mn-Si-rich sediments overlying oceanic basalts. High Fe, Ba, REE, U/Th values measured in black shales overlying mantle rocks in the proximal OCT point to a strong hydrothermal activity associated with mantle exhumation. The clastic sediments in the OCT show a wide range of compositions related to mantle, continental crust, and/or pelagic contributions. In particular, the fact that these sediments contain abundant material derived from continental basement rocks seems at odds with their occurrence on top of tectonized mantle rocks. However, drilling in the Iberia margin, where tectonized mantle rocks are overlain by sedimentary breccias (e.g. ODP Sites 1068, 1070), shed new light on the observations in the Alps. Based on drill-hole and seismic data, the tectono-sedimentary breccias drilled in the OCT off Iberia may be interpreted to result from a conveyor

  11. Abnormal gas-liquid-solid phase transition behaviour of water observed with in situ environmental SEM.

    PubMed

    Chen, Xin; Shu, Jiapei; Chen, Qing

    2017-04-24

    Gas-liquid-solid phase transition behaviour of water is studied with environmental scanning electron microscopy for the first time. Abnormal phenomena are observed. At a fixed pressure of 450 Pa, with the temperature set to -7 °C, direct desublimation happens, and ice grows continuously along the substrate surface. At 550 Pa, although ice is the stable phase according to the phase diagram, metastable liquid droplets first nucleate and grow to ~100-200 μm sizes. Ice crystals nucleate within the large sized droplets, grow up and fill up the droplets. Later, the ice crystals grow continuously through desublimation. At 600 Pa, the metastable liquid grows quickly, with some ice nuclei floating in it, and the liquid-solid coexistence state exists for a long time. By lowering the vapour pressure and/or increasing the substrate temperature, ice sublimates into vapour phase, and especially, the remaining ice forms a porous structure due to preferential sublimation in the concave regions, which can be explained with surface tension effect. Interestingly, although it should be forbidden for ice to transform into liquid phase when the temperature is well below 0 °C, liquid like droplets form during the ice sublimation process, which is attributed to the surface tension effect and the quasiliquid layers.

  12. Abnormal gas-liquid-solid phase transition behaviour of water observed with in situ environmental SEM

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Shu, Jiapei; Chen, Qing

    2017-04-01

    Gas-liquid-solid phase transition behaviour of water is studied with environmental scanning electron microscopy for the first time. Abnormal phenomena are observed. At a fixed pressure of 450 Pa, with the temperature set to -7 °C, direct desublimation happens, and ice grows continuously along the substrate surface. At 550 Pa, although ice is the stable phase according to the phase diagram, metastable liquid droplets first nucleate and grow to ~100-200 μm sizes. Ice crystals nucleate within the large sized droplets, grow up and fill up the droplets. Later, the ice crystals grow continuously through desublimation. At 600 Pa, the metastable liquid grows quickly, with some ice nuclei floating in it, and the liquid-solid coexistence state exists for a long time. By lowering the vapour pressure and/or increasing the substrate temperature, ice sublimates into vapour phase, and especially, the remaining ice forms a porous structure due to preferential sublimation in the concave regions, which can be explained with surface tension effect. Interestingly, although it should be forbidden for ice to transform into liquid phase when the temperature is well below 0 °C, liquid like droplets form during the ice sublimation process, which is attributed to the surface tension effect and the quasiliquid layers.

  13. Evolution of Shh endoderm enhancers during morphological transition from ventral lungs to dorsal gas bladder

    PubMed Central

    Sagai, Tomoko; Amano, Takanori; Maeno, Akiteru; Kimura, Tetsuaki; Nakamoto, Masatoshi; Takehana, Yusuke; Naruse, Kiyoshi; Okada, Norihiro; Kiyonari, Hiroshi; Shiroishi, Toshihiko

    2017-01-01

    Shh signalling plays a crucial role for endoderm development. A Shh endoderm enhancer, MACS1, is well conserved across terrestrial animals with lungs. Here, we first show that eliminating mouse MACS1 causes severe defects in laryngeal development, indicating that MACS1-directed Shh signalling is indispensable for respiratory organogenesis. Extensive phylogenetic analyses revealed that MACS1 emerged prior to the divergence of cartilaginous and bony fishes, and even euteleost fishes have a MACS1 orthologue. Meanwhile, ray-finned fishes evolved a novel conserved non-coding sequence in the neighbouring region. Transgenic assays showed that MACS1 drives reporter expression ventrally in laryngeal epithelium. This activity has been lost in the euteleost lineage, and instead, the conserved non-coding sequence of euteleosts acquired an enhancer activity to elicit dorsal epithelial expression in the posterior pharynx and oesophagus. These results implicate that evolution of these two enhancers is relevant to the morphological transition from ventral lungs to dorsal gas bladder. PMID:28155855

  14. Mechanism of gas saturated oil viscosity anomaly near to phase transition point

    NASA Astrophysics Data System (ADS)

    Suleimanov, Baghir A.; Abbasov, Elkhan M.; Sisenbayeva, Marziya R.

    2017-01-01

    The article presents experimental studies of the phase behavior by the flash liberation test and of the viscosity of the live oil at different pressures. Unlike the typical studies at the pressure near the saturation pressure, the measurements were conducted at a relatively small pressure increment of 0.08-0.25 MPa. The viscosity anomaly was discovered experimentally near to the phase transition point in the range of the pressure levels P/Pb = 1-1.14 (Pb—bubble point pressure) and shows that it decreases about 70 times in comparison to the viscosity at the reservoir pressure. It was found that the bubble point pressure decreases significantly (up to 36%) with surfactant addition. Furthermore, the viscosity of the live oil at the surfactant concentration of 5 wt. % decreases almost 37 times in comparison to the viscosity at the reservoir pressure. The mechanism of observed effects was suggested based on the formation of the stable subcritical gas nuclei and associated slippage effect. The mechanism for the stabilization of the subcritical nuclei by the combined action of the surface and electrical forces, as well as the morphology of the formed nanobubbles, was considered. The model for determining the oil viscosity taking into account the slippage effect was suggested.

  15. Accounting for exhaust gas transport dynamics in instantaneous emission models via smooth transition regression.

    PubMed

    Kamarianakis, Yiannis; Gao, H Oliver

    2010-02-15

    Collecting and analyzing high frequency emission measurements has become very usual during the past decade as significantly more information with respect to formation conditions can be collected than from regulated bag measurements. A challenging issue for researchers is the accurate time-alignment between tailpipe measurements and engine operating variables. An alignment procedure should take into account both the reaction time of the analyzers and the dynamics of gas transport in the exhaust and measurement systems. This paper discusses a statistical modeling framework that compensates for variable exhaust transport delay while relating tailpipe measurements with engine operating covariates. Specifically it is shown that some variants of the smooth transition regression model allow for transport delays that vary smoothly as functions of the exhaust flow rate. These functions are characterized by a pair of coefficients that can be estimated via a least-squares procedure. The proposed models can be adapted to encompass inherent nonlinearities that were implicit in previous instantaneous emissions modeling efforts. This article describes the methodology and presents an illustrative application which uses data collected from a diesel bus under real-world driving conditions.

  16. Widom line for the liquid-gas transition in Lennard-Jones system.

    PubMed

    Brazhkin, V V; Fomin, Yu D; Lyapin, A G; Ryzhov, V N; Tsiok, E N

    2011-12-08

    The locus of extrema (ridges) for heat capacity, thermal expansion coefficient, compressibility, and density fluctuations for model particle systems with Lennard-Jones (LJ) potential in the supercritical region have been obtained. It was found that the ridges for different thermodynamic values virtually merge into a single Widom line at T < 1.1T(c) and P < 1.5P(c) and become practically completely smeared at T < 2.5T(c) and P < 10P(c), where T(c) and P(c) are the critical temperature and pressure. The ridge for heat capacity approaches close to critical isochore, whereas the lines of extrema for other values correspond to density decrease. The lines corresponding to the supercritical maxima for argon and neon are in good agreement with the computer simulation data for LJ fluid. The behavior of the ridges for LJ fluid, in turn, is close to that for the supercritical van der Waals fluid, which is indicative of a fairly universal behavior of the Widom line for a liquid-gas transition.

  17. Transition.

    ERIC Educational Resources Information Center

    Thompson, Sandy, Ed.; And Others

    1990-01-01

    This "feature issue" focuses on transition from school to adult life for persons with disabilities. Included are "success stories," brief program descriptions, and a list of resources. Individual articles include the following titles and authors: "Transition: An Energizing Concept" (Paul Bates); "Transition…

  18. Transitional regimes of natural convection in a differentially heated cubical cavity under the effects of wall and molecular gas radiation

    NASA Astrophysics Data System (ADS)

    Soucasse, L.; Rivière, Ph.; Soufiani, A.; Xin, S.; Le Quéré, P.

    2014-02-01

    The transition to unsteadiness and the dynamics of weakly turbulent natural convection, coupled to wall or gas radiation in a differentially heated cubical cavity with adiabatic lateral walls, are studied numerically. The working fluid is air with small contents of water vapor and carbon dioxide whose infrared spectral radiative properties are modelled by the absorption distribution function model. A pseudo spectral Chebyshev collocation method is used to solve the flow field equations and is coupled to a direct ray tracing method for radiation transport. Flow structures are identified by means of either the proper orthogonal decomposition or the dynamic mode decomposition methods. We first retrieve the classical mechanism of transition to unsteadiness without radiation, characterized by counter-rotating streamwise-oriented vortices generated at the exit of the vertical boundary layers. Wall radiation through a transparent medium leads to a homogenization of lateral wall temperatures and the resulting transition mechanism is similar to that obtained with perfectly conducting lateral walls. The transition is due to an unstable stratification upstream the vertical boundary layers and is characterized by periodically oscillating transverse rolls of axis perpendicular to the main flow. When molecular gas radiation is accounted for, no periodic solution is found and the transition to unsteadiness displays complex structures with chimneys-like rolls whose axes are again parallel to the main flow. The origin of this instability is probably due to centrifugal forces, as suggested previously for the case without radiation. Above the transition to unsteadiness, at Ra = 3 × 108, it is shown that both wall and gas radiation significantly intensify turbulent fluctuations, decrease the thermal stratification in the core of the cavity, and increase the global circulation.

  19. Transitional regimes of natural convection in a differentially heated cubical cavity under the effects of wall and molecular gas radiation

    SciTech Connect

    Soucasse, L.; Rivière, Ph.; Soufiani, A.; Xin, S.

    2014-02-15

    The transition to unsteadiness and the dynamics of weakly turbulent natural convection, coupled to wall or gas radiation in a differentially heated cubical cavity with adiabatic lateral walls, are studied numerically. The working fluid is air with small contents of water vapor and carbon dioxide whose infrared spectral radiative properties are modelled by the absorption distribution function model. A pseudo spectral Chebyshev collocation method is used to solve the flow field equations and is coupled to a direct ray tracing method for radiation transport. Flow structures are identified by means of either the proper orthogonal decomposition or the dynamic mode decomposition methods. We first retrieve the classical mechanism of transition to unsteadiness without radiation, characterized by counter-rotating streamwise-oriented vortices generated at the exit of the vertical boundary layers. Wall radiation through a transparent medium leads to a homogenization of lateral wall temperatures and the resulting transition mechanism is similar to that obtained with perfectly conducting lateral walls. The transition is due to an unstable stratification upstream the vertical boundary layers and is characterized by periodically oscillating transverse rolls of axis perpendicular to the main flow. When molecular gas radiation is accounted for, no periodic solution is found and the transition to unsteadiness displays complex structures with chimneys-like rolls whose axes are again parallel to the main flow. The origin of this instability is probably due to centrifugal forces, as suggested previously for the case without radiation. Above the transition to unsteadiness, at Ra = 3 × 10{sup 8}, it is shown that both wall and gas radiation significantly intensify turbulent fluctuations, decrease the thermal stratification in the core of the cavity, and increase the global circulation.

  20. Sub-Doppler spectroscopy based on optical pumping and transit relaxation of atoms in a thin gas cell

    NASA Astrophysics Data System (ADS)

    Izmailov, Azad Ch.

    2007-06-01

    The paper is the review of methods, achievements, and possibilities of the recently elaborated and well tested high-resolution laser spectroscopy based on sub-Doppler absorption and polarization resonances (on centers of quantum transitions), which arise because of the optical pumping and specific transit relaxation of atoms (molecules) in a thin cell with a rarefied gas. Theoretical basis of this spectroscopy is presented. Experimental technique and results on the record of the sub-Doppler spectral structure of Cs and Rb atoms and on the frequency stabilization of diode lasers by given spectroscopy methods are discussed.

  1. Gas flow influence on streamer-to-leader transition in surface barrier discharge in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Akishev, Y.; Karalnik, V.; Medvedev, M.; Petryakov, A.; Trushkin, N.; Shafikov, A.

    2017-01-01

    The experimental results on study of a sinusoidal surface barrier discharge (SBD) in airflow at different velocities are presented. Influence of gas flow velocity and its orientation on plasma structure of SBD is established and the conditions providing transition of SBD from the streamer mode to the mode with surface leaders (SL) are found out as well. It is shown the formation of the SL in SBD happens owing to thermal effects associated with a local gas heating in both the bright current spots disposed at the sharp edge of high-voltage electrode and thin current channels (streamers) originated from these spots. It was revealed that gas flow with a high velocity directed against the propagation of surface streamers leads to destruction of the bright anode spots and elimination of the SL (but not the streamers) on a barrier surface. However the gas flow with the same velocity but opposite direction leads to regular disposition of the bright current spots at the edge of high-voltage electrode and regular spatial structure of the thin current channels (streamers and leaders) originated from the current spots. It was found out that gas flow of any orientation leads to diminishing the gas temperature in the plasma channels compared to that in SBD in gas at rest.

  2. Infrared and far-infrared transition frequencies for the CH2 radical. [in interstellar gas clouds

    NASA Technical Reports Server (NTRS)

    Sears, T. J.; Mckellar, A. R. W.; Bunker, P. R.; Evenson, K. M.; Brown, J. M.

    1984-01-01

    A list of frequencies and intensities for transitions of CH2 in the middle and far infrared regions is presented which should aid in the detection of CH2 and provide valuable information on the local physical and chemical environment. Results are presented for frequency, vacuum wavelength, and line strength for rotational transition frequencies and for the transition frequencies of the v(2) band.

  3. Protein conformational transitions at the liquid-gas interface as studied by dilational surface rheology.

    PubMed

    Noskov, Boris A

    2014-04-01

    Experimental results on the dynamic dilational surface elasticity of protein solutions are analyzed and compared. Short reviews of the protein behavior at the liquid-gas interface and the dilational surface rheology precede the main sections of this work. The kinetic dependencies of the surface elasticity differ strongly for the solutions of globular and non-globular proteins. In the latter case these dependencies are similar to those for solutions of non-ionic amphiphilic polymers and have local maxima corresponding to the formation of the distal region of the surface layer (type I). In the former case the dynamic surface elasticity is much higher (>60 mN/m) and the kinetic dependencies are monotonical and similar to the data for aqueous dispersions of solid nanoparticles (type II). The addition of strong denaturants to solutions of bovine serum albumin and β-lactoglobulin results in an abrupt transition from the type II to type I dependencies if the denaturant concentration exceeds a certain critical value. These results give a strong argument in favor of the preservation of the protein globular structure in the course of adsorption without any denaturants. The addition of cationic surfactants also can lead to the non-monotonical kinetic dependencies of the dynamic surface elasticity indicating destruction of the protein tertiary and secondary structures. The addition of anionic surfactants gives similar results only for the protein solutions of high ionic strength. The influence of cationic surfactants on the local maxima of the kinetic dependencies of the dynamic surface elasticity for solutions of a non-globular protein (β-casein) differs from the influence of anionic surfactants due to the heterogeneity of the charge distribution along the protein chain. In this case one can use small admixtures of ionic surfactants as probes of the adsorption mechanism. The effect of polyelectrolytes on the kinetic dependencies of the dynamic surface elasticity of protein

  4. The success of Fermi gas model for overall scaling of 2D metal-to-insulator transition data

    NASA Astrophysics Data System (ADS)

    Cheremisin, M. V.

    2017-03-01

    The melting condition for two-dimensional Wigner solid (Platzman and Fukuyama, 1974) [14] is shown to contain an error of a factor of π. The analysis of experimental data for apparent 2D metal-to-insulator transition shows that the Wigner solidification (Tanatar and Ceperley, 1989) [16] has been never achieved. Within routine Fermi gas model both the metallic and insulating behavior of different 2D system for actual range of carrier densities and temperatures is explained.

  5. Higher-order baryon number susceptibilities: Interplay between the chiral and the nuclear liquid-gas transitions

    NASA Astrophysics Data System (ADS)

    Mukherjee, A.; Steinheimer, J.; Schramm, S.

    2017-08-01

    We use an improved version of the SU(3) flavor parity-doublet quark-hadron model to investigate the higher-order baryon number susceptibilities near the chiral and the nuclear liquid-gas transitions. The parity-doublet model has been improved by adding higher-order interaction terms of the scalar fields in the effective mean field Lagrangian, resulting in a much-improved description of nuclear ground-state properties, in particular the nuclear compressibility. The resulting phase diagram of the model agrees qualitatively with expectations from lattice QCD, i.e., it shows a crossover at zero net baryochemical potential and a critical point at finite density. Using this model, we investigate the dependence of the higher-order baryon number susceptibilities as a function of temperature and chemical potential. We observe a strong interplay between the chiral and liquid-gas transition at intermediate baryochemical potentials. Due to this interplay between the chiral and the nuclear liquid-gas transitions, the experimentally measured cumulants of the net baryon number may show very different beam energy dependence, subject to the actual freeze-out temperature.

  6. Development, Application, and Transition of Aerosol and Trace Gas Products Derived from Next-Generation Satellite Observations to Operations

    NASA Technical Reports Server (NTRS)

    Berndt, Emily; Naeger, Aaron; Zavodsky, Bradley; McGrath, Kevin; LaFontaine, Frank

    2016-01-01

    NASA Short-term Prediction Research and Transition (SPoRT) Center has a history of successfully transitioning unique observations and research capabilities to the operational weather community to improve short-term forecasts. SPoRTstrives to bridge the gap between research and operations by maintaining interactive partnerships with end users to develop products that match specific forecast challenges, provide training, and assess the products in the operational environment. This presentation focuses on recent product development, application, and transition of aerosol and trace gas products to operations for specific forecasting applications. Recent activities relating to the SPoRT ozone products, aerosol optical depth composite product, sulfur dioxide, and aerosol index products are discussed.

  7. Clean air program: Design guidelines for bus transit systems using liquefied petroleum gas (LPG) as an alternative fuel. Final report, July 1995-April 1996

    SciTech Connect

    Raj, P.K.; Hathaway, W.T.; Kangas, R.

    1996-09-01

    The Federal Transit Administration (FTA) has initiated the development of `Design Guidelines for Bus Transit Systems Using Alternative Fuels.` This report provides design guidelines for the safe uses of Liquefied Petroleum Gas (LPG). It forms a part of the series of individual monographs being published by the FTA on (the guidelines for the safe use of) Compressed Natural Gas (CNG), Liquefied Natural Gas (LNG), Liquefied Petroleum Gas (LPG) and alcohol fuels (Methanol and Ethanol). Each report in this series describes for the subject fuel the important fuel properties, guidelines for the design and operation of bus fueling, storage and maintenance facilities, issues on personnel training and emergency preparedness.

  8. Generation, Detection and characterization of Gas-Phase Transition Metal containing Molecules

    SciTech Connect

    Steimle, Timothy

    2015-12-15

    The objective of this project was to generate, detect, and characterize small, gas-phase, metal containing molecules. In addition to being relevant to high temperature chemical environments (e.g. plasmas and combustion), gas-phase experiments on metal containing molecules serve as the most direct link to a molecular-level theoretical model for catalysis. Catalysis (i.e. the addition of a small about of recoverable material to control the rate and direction of a chemical reaction) is critical to the petroleum and pharmaceutical industries as well as environmental remediation. Currently, the majority of catalytic materials are based on very expensive metals such as platinum (Pt), palladium (Pd), iridium (Ir,) rhenium (Re), and rhodium (Rh). For example, the catalyst used for converting linear hydrocarbon molecules (e.g. hexane) to cyclic molecules (e.g. cyclohexane) is a mixture of Pt and Re suspended on alumina. It enables straight chain alkanes to be converted into branched-chain alkanes, cyclohexanes and aromatic hydrocarbons which are used, amongst other things, to enhance the octane number of petrol. A second example is the heterogeneous catalysis used in automobile exhaust systems to: a) decrease nitrogen oxide; b) reduce carbon monoxide; and c) oxidize unburned hydrocarbons. The exhaust is vented through a high-surface area chamber lined with Pt, Pd, and Rh. For example, the carbon monoxide is catalytically converted to carbon dioxide by reaction with oxygen. The research results from this work have been published in readily accessible journals1-28. The ground and excited electronic state properties of small metal containing molecules that we determine were: a) electronic state distributions and lifetimes, b) vibrational frequencies, c) bond lengths and angles, d) hyperfine interactions, e) permanent electric dipole moments, mel, and f) magnetic dipoles, μm. In general terms, μel, gives insight into the charge distribution and mm into

  9. Preparation and Thermodynamics of High Critical Transition Temperature Superconducting Films Growth by Liquid-Gas Process

    NASA Astrophysics Data System (ADS)

    Chou, Hsiung

    The in situ Tl-base superconducting films have been grown successfully on MgO and SrTiO_3 < 100> substrates by Liquid-Gas-Solidification (LGS) process. The loss of Tl during growth process can be nearly eliminated by a proper geometry design of the LGS set up. there is no post anneal for forming the right structure or compensation of Tl applied after the initial deposition. The Tl-base films grown on MgO < 100> exhibits an oriented structure with c-axis perpendicular to the surface of substrates. X-ray diffraction patterns reveal a coexistence of multi-phases in the films. The morphology of films shows flat and uniform domains of 0.5 times 1 mm^2. It exhibits a resistant transition onset of 117K and zero resistance at 103K. In the films grown on SrTiO _3 < 100> substrate, Ca-O precipitations on the edge of the film layer are observed. Upon a post anneal process, the Ca -O precipitates disappear resulted in an enhanced transport critical current density of 10^{-5 } A/cm^2. In forming the oxide film in LGS processing, oxygen is absorbed and diffuses into the liquid alloy reaching the liquid-substrate interface to form the oxide. The nucleation and growth of the films is a matter of the thermodynamic and the kinetic behavior of oxygen in the liquid precursor. A modified coulometric titration method is introduced to understand this behavior and to measure the activity, diffusivity and solubility of oxygen in the liquid high T_ {rm c} superconducting precursor alloys, rm Yb_1Ba_2Cu_3 , Ag-Yb_1Ba_2 Cu_3 and rm Tl_1Ba_2Ca_2Cu_3. In all alloy systems investigated, the formation energy of oxygen dissolved into the liquid alloys is relatively low ({~}{-}255 kJ/g-atom) which is attributed to the present of rare earth elements of Ba, Ca and Yb. The high affinity of oxygen with these elements results in a limited oxygen solubility (10^{-4} molar fraction), however, the diffusion coefficients of oxygen in the liquid alloys are high of the order of 10^{ -4} cm^2/sec. These

  10. Gas

    MedlinePlus

    ... intestine. Certain foods may cause gas. Foods that produce gas in one person may not cause gas in another. You can reduce the amount of gas you have by Drinking lots of water and non-fizzy drinks Eating more slowly so you swallow less air ...

  11. Peatlands in a eutrophic world - assessing the state of a poor fen-bog transition in southern Ontario, Canada, after long term nutrient input and altered hydrological conditions

    NASA Astrophysics Data System (ADS)

    Berger, Sina; Gebauer, Gerhard; Blodau, Christian; Knorr, Klaus-Holger

    2017-04-01

    Peatlands are of vital importance for global carbon (C) cycling as they sequester and store enormous amounts of C. Major threats to peatlands are excessive supply of nutrients from the atmosphere as well as from surface water and groundwater. Up to this date our knowledge of long-term consequences of such excessive nutrient supply is limited. We are unsure about how long peatlands can maintain their functioning under such circumstances. We conducted a detailed study in a once ombrotrophic bog ecosystem (Wylde Lake peatland, Ontario, Canada), which is since the 19th century embedded in a eutrophic environment with intensive agriculture. Moreover, since AD 1954 the peatland borders a water reservoir which is strongly enriched with nutrients. Our objective was to elucidate to which extent the infiltration of nutrient from the peatland periphery can be buffered and whether the inner parts can maintain typical characteristics of a pristine bog. To achieve this goal, along a transect of study sites, we Pb-210- and Cs-137-dated peat cores and determined elements of peat using x-ray fluorescence (XRF). To calculate N input, nitrogen enrichment factors in the vegetation and abundances of stable N isotopes in the peat were determined through isotope ratio mass spectrometry (IRMS). Furthermore, we re-investigated the vascular plant species composition 31 years after a previous investigation and lastly, we sporadically measured greenhouse gas fluxes with chamber techniques. In the central part of the peatland we found great N input rates of 4.28±0.75 and 4.35±0.30 g N m-2 y-1, but even greater rates were found in the peatland fringe area (5.90±0.10 g N m-2 y-1). Also, all elements essential for plant growth were abundant in increased concentrations along all peat cores, especially near the bordering reservoir, presumably due to supply by the reservoir water. A more graminoid dominated vegetation in the wetter areas (near the reservoir) and a rapid increase of tree cover in

  12. Improved Log(gf) Values for Lines of Ti I and Abundance Determinations in the Photospheres of the Sun and Metal-Poor Star HD 84937 (Accurate Transition Probabilities for Ti I)

    NASA Astrophysics Data System (ADS)

    Lawler, J. E.; Guzman, A.; Wood, M. P.; Sneden, C.; Cowan, J. J.

    2013-04-01

    New atomic transition probability measurements for 948 lines of Ti I are reported. Branching fractions from Fourier transform spectra and from spectra recorded using a 3 m echelle spectrometer are combined with published radiative lifetimes from laser-induced fluorescence measurements to determine these transition probabilities. Generally good agreement is found in comparisons to the NIST Atomic Spectra Database. The new Ti I data are applied to re-determine the Ti abundance in the photospheres of the Sun and metal-poor star HD 84937 using many lines covering a range of wavelength and excitation potential to explore possible non-local thermal equilibrium effects. The variation of relative Ti/Fe abundance with metallicity in metal-poor stars observed in earlier studies is supported in this study.

  13. IMPROVED log(gf) VALUES FOR LINES OF Ti I AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937 (ACCURATE TRANSITION PROBABILITIES FOR Ti I)

    SciTech Connect

    Lawler, J. E.; Guzman, A.; Wood, M. P.; Sneden, C.; Cowan, J. J. E-mail: adrianaguzman2014@u.northwestern.edu E-mail: chris@verdi.as.utexas.edu

    2013-04-01

    New atomic transition probability measurements for 948 lines of Ti I are reported. Branching fractions from Fourier transform spectra and from spectra recorded using a 3 m echelle spectrometer are combined with published radiative lifetimes from laser-induced fluorescence measurements to determine these transition probabilities. Generally good agreement is found in comparisons to the NIST Atomic Spectra Database. The new Ti I data are applied to re-determine the Ti abundance in the photospheres of the Sun and metal-poor star HD 84937 using many lines covering a range of wavelength and excitation potential to explore possible non-local thermal equilibrium effects. The variation of relative Ti/Fe abundance with metallicity in metal-poor stars observed in earlier studies is supported in this study.

  14. The Sizes and Depletions of the Dust and Gas Cavities in the Transitional Disk J160421.7-213028

    NASA Astrophysics Data System (ADS)

    Dong, Ruobing; van der Marel, Nienke; Hashimoto, Jun; Chiang, Eugene; Akiyama, Eiji; Liu, Hauyu Baobab; Muto, Takayuki; Knapp, Gillian R.; Tsukagoshi, Takashi; Brown, Joanna; Bruderer, Simon; Koyamatsu, Shin; Kudo, Tomoyuki; Ohashi, Nagayoshi; Rich, Evan; Satoshi, Mayama; Takami, Michihiro; Wisniewski, John; Yang, Yi; Zhu, Zhaohuan; Tamura, Motohide

    2017-02-01

    We report ALMA Cycle 2 observations of 230 GHz (1.3 mm) dust continuum emission, and 12CO, 13CO, and C18O J = 2–1 line emission, from the Upper Scorpius transitional disk [PZ99] J160421.7-213028, with an angular resolution of ∼0\\buildrel{\\prime\\prime}\\over{.} 25 (35 au). Armed with these data and existing H-band scattered light observations, we measure the size and depth of the disk’s central cavity, and the sharpness of its outer edge, in three components: sub-μm-sized “small” dust traced by scattered light, millimeter-sized “big” dust traced by the millimeter continuum, and gas traced by line emission. Both dust populations feature a cavity of radius ∼70 au that is depleted by factors of at least 1000 relative to the dust density just outside. The millimeter continuum data are well explained by a cavity with a sharp edge. Scattered light observations can be fitted with a cavity in small dust that has either a sharp edge at 60 au, or an edge that transitions smoothly over an annular width of 10 au near 60 au. In gas, the data are consistent with a cavity that is smaller, about 15 au in radius, and whose surface density at 15 au is {10}3+/- 1 times smaller than the surface density at 70 au; the gas density grades smoothly between these two radii. The CO isotopologue observations rule out a sharp drop in gas surface density at 30 au or a double-drop model, as found by previous modeling. Future observations are needed to assess the nature of these gas and dust cavities (e.g., whether they are opened by multiple as-yet-unseen planets or photoevaporation).

  15. The Dicke Quantum Phase Transition in a Superfluid Gas Coupled to an Optical Cavity

    NASA Astrophysics Data System (ADS)

    Guerlin, Christine; Baumann, Kristian; Brennecke, Ferdinand; Esslinger, Tilman

    2010-03-01

    A fundamental approach to collective matter-light interaction is given by the Dicke model which has been predicted to show an intriguing quantum phase transition. We have realized the Dicke quantum phase transition in an open system formed by a Bose-Einstein condensate coupled to an optical cavity, and observed the emergence of a self-organized supersolid phase [1]. The phase transition is driven by infinitely long-ranged interactions between the condensed atoms. We show that the phase transition is described by the Dicke Hamiltonian, including counter-rotating coupling terms, and that the supersolid phase is associated with a spontaneously broken spatial symmetry. The boundary of the phase transition is mapped out in quantitative agreement with the Dicke model. [4pt] [1] K. Baumann, C. Guerlin, F. Brennecke, T. Esslinger, arXiv 0912.2361, 2009

  16. Direct detection of Rydberg-Rydberg millimeter-wave transitions in a buffer gas cooled molecular beam

    NASA Astrophysics Data System (ADS)

    Zhou, Yan; Grimes, David D.; Barnum, Timothy J.; Patterson, David; Coy, Stephen L.; Klein, Ethan; Muenter, John S.; Field, Robert W.

    2015-11-01

    Millimeter-wave transitions between molecular Rydberg states (n ∼ 35) of barium monofluoride are directly detected via Free Induction Decay (FID). Two powerful technologies are used in combination: Chirped-Pulse millimeter-Wave (CPmmW) spectroscopy and a buffer gas cooled molecular beam photoablation source. Hundreds of Rydberg-Rydberg transitions are recorded in 1 h with >10:1 signal:noise ratio and ∼150 kHz resolution. This high resolution, high spectral velocity experiment promises new strategies for rapid measurements of structural and dynamical information, such as the electric structure (multipole moments and polarizabilities) of the molecular ion-core and the strengths and mechanisms of resonances between Rydberg electron and ion-core motions. Direct measurements of Rydberg-Rydberg transitions with kilo-Debye dipole moments support efficient and definitive spectral analysis techniques, such as the Stark demolition and polarization diagnostics, which enable semi-automatic assignments of core-nonpenetrating Rydberg states. In addition, extremely strong radiation-mediated collective effects (superradiance) in a dense Rydberg gas of barium atoms are observed.

  17. Mobility of Supercooled liquid Toluene, Ethylbenzene, and Benzene near their Glass Transition Temperatures Investigated using Inert Gas Permeation

    SciTech Connect

    May, Robert A.; Smith, R. Scott; Kay, Bruce D.

    2013-11-21

    We investigate the mobility of supercooled liquid toluene, ethylbenzene, and benzene near their respective glass transition temperatures (Tg). The permeation rate of Ar, Kr, and Xe through the supercooled liquid created when initially amorphous overlayers heated above their glass transition temperature is used to determine the diffusivity. Amorphous benzene crystallizes at temperatures well below its Tg and as a result the inert gas underlayer remains trapped until the onset of benzene desorption. In contrast, for toluene and ethylbenzene the onset of inert gas permeation is observed at temperatues near Tg. The inert gas desorption peak temperature as a function of the heating rate and overlayer thickness is used to quantify the diffusivity of supercooled liquid toluene and ethylbenzene from 115 K to 135 K. In this temperature range, diffusivities are found to vary across five orders of magnitude (~10-14 to 10-9 cm2/s). These data are compared to viscosity measurements and used to determine the low temperature fractional Stokes-Einstein exponent. Efforts to determine the diffusivity of a mixture of benzene and ethylbenzene are detailed, and the effect of mixing these materials on benzene crystallization is explored using infrared spectroscopy.

  18. Mobility of supercooled liquid toluene, ethylbenzene, and benzene near their glass transition temperatures investigated using inert gas permeation.

    PubMed

    May, R Alan; Smith, R Scott; Kay, Bruce D

    2013-11-21

    We investigate the mobility of supercooled liquid toluene, ethylbenzene, and benzene near their respective glass transition temperatures (Tg). The permeation rate of Ar, Kr, and Xe through the supercooled liquid created when initially amorphous overlayers are heated above their glass transition temperature is used to determine the diffusivity. Amorphous benzene crystallizes at temperatures well below its Tg, and as a result, the inert gas underlayer remains trapped until the onset of benzene desorption. In contrast, for toluene and ethylbenzene the onset of inert gas permeation is observed at temperatues near Tg. The inert gas desorption peak temperature as a function of the heating rate and overlayer thickness is used to quantify the diffusivity of supercooled liquid toluene and ethylbenzene from 115 to 135 K. In this temperature range, diffusivities are found to vary across 5 orders of magnitude (∼10(-14) to 10(-9) cm(2)/s). The diffusivity data are compared to viscosity measurements and reveal a breakdown in the Stokes-Einstein relationship at low temperatures. However, the data are well fit by the fractional Stokes-Einstein equation with an exponent of 0.66. Efforts to determine the diffusivity of a mixture of benzene and ethylbenzene are detailed, and the effect of mixing these materials on benzene crystallization is explored using infrared spectroscopy.

  19. EFFECTS OF TRITIUM GAS EXPOSURE ON THE GLASS TRANSITION TEMPERATURE OF EPDM ELASTOMER AND ON THE CONDUCTIVITY OF POLYANILINE

    SciTech Connect

    Clark, E; Marie Kane, M

    2008-12-12

    Four formulations of EPDM (ethylene-propylene diene monomer) elastomer were exposed to tritium gas initially at one atmosphere and ambient temperature for between three and four months in closed containers. Material properties that were characterized include density, volume, mass, appearance, flexibility, and dynamic mechanical properties. The glass transition temperature was determined by analysis of the dynamic mechanical property data per ASTM standards. EPDM samples released significant amounts of gas when exposed to tritium, and the glass transition temperature increased by about 3 C. during the exposure. Effects of ultraviolet and gamma irradiation on the surface electrical conductivity of two types of polyaniline films are also documented as complementary results to planned tritium exposures. Future work will determine the effects of tritium gas exposure on the electrical conductivity of polyaniline films, to demonstrate whether such films can be used as a sensor to detect tritium. Surface conductivity was significantly reduced by irradiation with both gamma rays and ultraviolet light. The results of the gamma and UV experiments will be correlated with the tritium exposure results.

  20. Sensor transition failure in the high flow sampler: Implications for methane emission inventories of natural gas infrastructure.

    PubMed

    Howard, Touché; Ferrara, Thomas W; Townsend-Small, Amy

    2015-07-01

    Quantification of leaks from natural gas (NG) infrastructure is a key step in reducing emissions of the greenhouse gas methane (CH4), particularly as NG becomes a larger component of domestic energy supply. The U.S. Environmental Protection Agency (EPA) requires measurement and reporting of emissions of CH4 from NG transmission, storage, and processing facilities, and the high-flow sampler (or high-volume sampler) is one of the tools approved for this by the EPA. The Bacharach Hi-Flow Sampler (BHFS) is the only commercially available high-flow instrument, and it is also used throughout the NG supply chain for directed inspection and maintenance, emission factor development, and greenhouse gas reduction programs. Here we document failure of the BHFS to transition from a catalytic oxidation sensor used to measure low NG (~5% or less) concentrations to a thermal conductivity sensor for higher concentrations (from ~5% to 100%), resulting in underestimation of NG emission rates. Our analysis includes both our own field testing and analysis of data from two other studies (Modrak et al., 2012; City of Fort Worth, 2011). Although this failure is not completely understood, and although we do not know if all BHFS models are similarly affected, sensor transition failure has been observed under one or more of these conditions: (1) Calibration is more than ~2 weeks old; (2) firmware is out of date; or (3) the composition of the NG source is less than ~91% CH4. The extent to which this issue has affected recent emission studies is uncertain, but the analysis presented here suggests that the problem could be widespread. Furthermore, it is critical that this problem be resolved before the onset of regulations on CH4 emissions from the oil and gas industry, as the BHFS is a popular instrument for these measurements. An instrument commonly used to measure leaks in natural gas infrastructure has a critical sensor transition failure issue that results in underestimation of leaks, with

  1. Ultrabright multikilovolt x-ray source: saturated amplification on noble gas transition arrays from hollow atom states

    DOEpatents

    Rhodes, Charles K.; Boyer, Keith

    2004-02-17

    An apparatus and method for the generation of ultrabright multikilovolt x-rays from saturated amplification on noble gas transition arrays from hollow atom states is described. Conditions for x-ray amplification in this spectral region combine the production of cold, high-Z matter, with the direct, selective multiphoton excitation of hollow atoms from clusters using ultraviolet radiation and a nonlinear mode of confined, self-channeled propagation in plasmas. Data obtained is consistent with the presence of saturated amplification on several transition arrays of the hollow atom Xe(L) spectrum (.lambda..about.2.9 .ANG.). An estimate of the peak brightness achieved is .about.10.sup.29 .gamma..multidot.s.sup.-1.multidot.mm.sup.-2.multidot.mr.sup.-2 (0.1% Bandwidth).sup.-1, that is .about.10.sup.5 -fold higher than presently available synchotron technology.

  2. Buoyancy Effects on Flow Transition in Low-Density Inertial Gas Jets

    NASA Technical Reports Server (NTRS)

    Pasumarthi, Kasyap S.; Agrawal, Ajay K.

    2005-01-01

    Effects of buoyancy on transition from laminar to turbulent flow are presented for momentum-dominated helium jet injected into ambient air. The buoyancy was varied in a 2.2-sec drop tower facility without affecting the remaining operating parameters. The jet flow in Earth gravity and microgravity was visualized using the rainbow schlieren deflectometry apparatus. Results show significant changes in the flow structure and transition behavior in the absence of buoyancy.

  3. Transition to zero resistance in a two-dimensional electron gas driven with microwaves

    NASA Astrophysics Data System (ADS)

    Alicea, Jason; Balents, Leon; Fisher, Matthew P. A.; Paramekanti, Arun; Radzihovsky, Leo

    2005-06-01

    High-mobility two-dimensional electron systems in a perpendicular magnetic field exhibit zero-resistance states (ZRSs) when driven with microwave radiation. We study the nonequilibrium phase transition into the ZRS using phenomenological equations of motion to describe the electron current and density fluctuations in the presence of a magnetic field. We focus on two models to describe the transition into a time-independent steady state. In model I the equations of motion are invariant under a global uniform change in the density. This model is argued to describe physics on small length scales where the density does not vary appreciably from its mean. The ordered state that arises in this case spontaneously breaks rotational invariance in the plane and consists of a uniform current and a transverse Hall field. We discuss some properties of this state, such as stability to fluctuations and the appearance of a Goldstone mode associated with the continuous symmetry breaking. Using dynamical renormalization group techniques, we find that with short-range interactions this model can admit a continuous transition described by mean-field theory, whereas with long-range interactions the transition is driven first order. In model II, we relax the invariance under global density shifts as appropriate for describing the system on longer length scales, and in this case we predict a first-order transition with either short- or long-range interactions. We discuss implications for experiments, including a possible way to detect the Goldstone mode in the ZRS, scaling relations expected to hold in the case of an apparent continuous transition into the ZRS, and a possible signature of a first-order transition in larger samples. Our framework for describing the phase transition into the ZRS also highlights the connection of this problem to the well-studied phenomenon of “bird flocking.”

  4. Comparison of the dust and gas radial structure in the transition disk [PZ99] J160421.7-213028

    SciTech Connect

    Zhang, Ke; Isella, Andrea; Carpenter, John M.; Blake, Geoffrey A.

    2014-08-10

    We present ALMA observations of the 880 μm continuum and CO J = 3-2 line emission from the transition disk around [PZ99] J160421.7-213028, a solar mass star in the Upper Scorpius OB association. Analysis of the continuum data indicates that 80% of the dust mass is concentrated in an annulus extending between 79 and 114 AU in radius. Dust is robustly detected inside the annulus, at a mass surface density 100 times lower than that at 80 AU. The CO emission in the inner disk also shows a significantly decreased mass surface density, but we infer a cavity radius of only 31 AU for the gas. The large separation of the dust and gas cavity edges, as well as the high radial concentration of millimeter-sized dust grains, is qualitatively consistent with the predictions of pressure trap models that include hydrodynamical disk-planet interactions and dust coagulation/fragmentation processes.

  5. The Moment Analysis Method as Applied to the 2S-2P Transition in Cryogenic Alkali Metal/Rare Gas Matrices (PREPRINT)

    DTIC Science & Technology

    2005-12-05

    spectroscopy of alkali metal atoms trapped in cryogenic noble gas matrices. Master’s thesis, Eastern New Mexico University, 1993. [31] J. W...Cryogenic Alkali Metal/Rare Gas Matrices (PREPRINT) 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Heidi A. Terrill Vosbein (Stennis...the case of 2 S→2P ([core]ns1→[core]np1) transitions of alkali metal atoms (M) doped into cryogenic rare gas (Rg) matrices using theoretically

  6. The Moment Analysis Method as Applied to the (2)S yields (2)P Transition in Cryogenic Alkali Metal/Rare Gas Matrices

    DTIC Science & Technology

    2005-12-14

    dichroism spectroscopy of alkali metal atoms trapped in cryogenic noble gas matrices. Master’s thesis, Eastern New Mexico University, 1993. (31...Cryogenic Alkali Metal/Rare Gas Matrices (POSTPRINT) 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Heidi A. Terrill Vosbein (Stennis...been tested for the case of 2 S→2P ([core]ns1→[core]np1) transitions of alkali metal atoms (M) doped into cryogenic rare gas (Rg) matrices using

  7. Electronic Stopping of Slow Protons in Transition and Rare Earth Metals: Breakdown of the Free Electron Gas Concept.

    PubMed

    Roth, D; Bruckner, B; Moro, M V; Gruber, S; Goebl, D; Juaristi, J I; Alducin, M; Steinberger, R; Duchoslav, J; Primetzhofer, D; Bauer, P

    2017-03-10

    The electronic stopping cross sections (SCS) of Ta and Gd for slow protons have been investigated experimentally. The data are compared to the results for Pt and Au to learn how electronic stopping in transition and rare earth metals correlates with features of the electronic band structures. The extraordinarily high SCS observed for protons in Ta and Gd cannot be understood in terms of a free electron gas model, but are related to the high densities of both occupied and unoccupied electronic states in these metals.

  8. Electronic Stopping of Slow Protons in Transition and Rare Earth Metals: Breakdown of the Free Electron Gas Concept

    NASA Astrophysics Data System (ADS)

    Roth, D.; Bruckner, B.; Moro, M. V.; Gruber, S.; Goebl, D.; Juaristi, J. I.; Alducin, M.; Steinberger, R.; Duchoslav, J.; Primetzhofer, D.; Bauer, P.

    2017-03-01

    The electronic stopping cross sections (SCS) of Ta and Gd for slow protons have been investigated experimentally. The data are compared to the results for Pt and Au to learn how electronic stopping in transition and rare earth metals correlates with features of the electronic band structures. The extraordinarily high SCS observed for protons in Ta and Gd cannot be understood in terms of a free electron gas model, but are related to the high densities of both occupied and unoccupied electronic states in these metals.

  9. Metastable quantum phase transitions in a periodic one-dimensional Bose gas. II. Many-body theory

    SciTech Connect

    Kanamoto, R.; Carr, L. D.; Ueda, M.

    2010-02-15

    We show that quantum solitons in the Lieb-Liniger Hamiltonian are precisely the yrast states. We identify such solutions with Lieb's type II excitations from weak to strong interactions, clarifying a long-standing question of the physical meaning of this excitation branch. We demonstrate that the metastable quantum phase transition previously found in mean-field analysis of the weakly interacting Lieb-Liniger Hamiltonian [Phys. Rev. A 79, 063616 (2009)] extends into the medium- to strongly interacting regime of a periodic one-dimensional Bose gas. Our methods are exact diagonalization, finite-size Bethe ansatz, and the boson-fermion mapping in the Tonks-Girardeau limit.

  10. Crossover behavior in the phase transition of the Bose-Einstein condensation in a microwave-driven magnon gas

    SciTech Connect

    Rezende, Sergio M.

    2009-09-01

    A magnon gas in a film of yttrium iron garnet driven by microwave radiation exhibits Bose-Einstein condensation (BEC) when the driving power exceeds a critical value. We show that the nature and the critical exponents of the BEC transition change dramatically if the BEC magnons are significantly coupled to the zone-center magnons. The theoretical results explain the diverse behavior of the order parameter inferred from the experimental data for the light scattering and the microwave emission from the BEC observed with coherent and incoherent microwave pumping.

  11. Nature of the interaction between rare gas atoms and transition metal doped silicon clusters: the role of shielding effects.

    PubMed

    Ngan, Vu Thi; Janssens, Ewald; Claes, Pieterjan; Fielicke, André; Nguyen, Minh Tho; Lievens, Peter

    2015-07-21

    Mass spectrometry experiments show an exceptionally weak bonding between Si7Mn(+) and rare gas atoms as compared to other exohedrally transition metal (TM) doped silicon clusters and other SinMn(+) (n = 5-10) sizes. The Si7Mn(+) cluster does not form Ar complexes and the observed fraction of Xe complexes is low. The interaction of two cluster series, SinMn(+) (n = 6-10) and Si7TM(+) (TM = Cr, Mn, Cu, and Zn), with Ar and Xe is investigated by density functional theory calculations. The cluster-rare gas binding is for all clusters, except Si7Mn(+) and Si7Zn(+), predominantly driven by short-range interaction between the TM dopant and the rare gas atoms. A high s-character electron density on the metal atoms in Si7Mn(+) and Si7Zn(+) shields the polarization toward the rare gas atoms and thereby hinders formation of short-range complexes. Overall, both Ar and Xe complexes are similar except that the larger polarizability of Xe leads to larger binding energies.

  12. Effect of Non-Condensable Gas on Cavity Dynamics and Sheet to Cloud Transition

    NASA Astrophysics Data System (ADS)

    Makiharju, Simo; Ganesh, Harish; Ceccio, Steven

    2014-11-01

    Partial cavitation occurs in numerous industrial and naval applications. Cavities on lifting surfaces, in cryogenic rocket motors or in fuel injectors can damage equipment and in general be detrimental to the system performance, especially as partial cavities can undergo auto-oscillation causing large pressure pulsations, unsteady loading of machinery and generate significant noise. In the current experiments incipient, intermittent cloud shedding and fully shedding cavities forming in the separated flow region downstream of a wedge were investigated. The Reynolds number based on hydraulic diameter was of the order of one million. Gas was injected directly into the cavitation region downstream of the wedge's apex or into the recirculating region such that with the same amount of injected gas less ended up in the shear layer. The cavity dynamics were studied with and without gas injection. The hypothesis to be tested were that i) relatively miniscule amounts of gas introduced into the shear layer at the cavity interface can reduce vapor production and ii) gas introduced into the separated region can dampen the auto oscillations. The authors also examined whether the presence of gas can switch the shedding mechanism from one dominated by condensation shock to one dominantly by re-entrant jet. The work was supported by ONR Grant Number N00014-11-1-0449.

  13. Body Dissatisfaction, Living Away from Parents, and Poor Social Adjustment Predict Binge Eating Symptoms in Young Women Making the Transition to University

    ERIC Educational Resources Information Center

    Barker, Erin T.; Galambos, Nancy L.

    2007-01-01

    The current study explored how body dissatisfaction and challenges associated with the transition to university predicted symptoms of binge eating. Participants were 101 female full-time first-year university students (M=18.3 years of age; SD=0.50) who completed a background questionnaire and a web-based daily checklist assessing binge eating.…

  14. Body Dissatisfaction, Living Away from Parents, and Poor Social Adjustment Predict Binge Eating Symptoms in Young Women Making the Transition to University

    ERIC Educational Resources Information Center

    Barker, Erin T.; Galambos, Nancy L.

    2007-01-01

    The current study explored how body dissatisfaction and challenges associated with the transition to university predicted symptoms of binge eating. Participants were 101 female full-time first-year university students (M=18.3 years of age; SD=0.50) who completed a background questionnaire and a web-based daily checklist assessing binge eating.…

  15. Surface-induced liquid-gas transition in salt-free solutions of model charged colloids.

    PubMed

    Budkov, Yu A; Frolov, A I; Kiselev, M G; Brilliantov, N V

    2013-11-21

    We report a novel phenomenon of a surface-induced phase transition in salt-free solutions of charged colloids. We develop a theory of this effect and confirm it by Molecular Dynamics simulations. To describe the colloidal solution we apply a primitive model of electrolyte with a strong asymmetry of charge and size of the constituent particles - macroions and counterions. To quantify interactions of the colloidal particles with the neutral substrate we use a short-range potential which models dispersion van der Waals forces. These forces cause the attraction of colloids to the surface. We show that for high temperatures and weak attraction, only gradual increase of the macroion concentration in the near-surface layer is observed with increase of interaction strength. If however temperature drops below some threshold value, a new dense (liquid) phase is formed in the near-surface layer. It can be interpreted as a surface-induced first-order phase transition with a critical point. Using an appropriately adopted Maxwell construction, we find the binodal. Interestingly, the observed near-surface phase transition can occur at the absence of the bulk phase transition and may be seemingly classified as prewetting transition. The reported effect could be important for various technological applications where formation of colloidal particle layers with the desired properties is needed.

  16. Unintended greenhouse gas consequences of lowering level of service in urban transit systems

    NASA Astrophysics Data System (ADS)

    Griswold, Julia B.; Cheng, Han; Madanat, Samer; Horvath, Arpad

    2014-12-01

    Public transit is often touted as a ‘green’ transportation option and a way for users to reduce their environmental footprint by avoiding automobile emissions, but that may not be the case when systems run well below passenger capacity. In previous work, we explored an approach to optimizing the design and operations of transit systems for both costs and emissions, using continuum approximation models and assuming fixed demand. In this letter, we expand upon our previous work to explore how the level of service for users impacts emissions. We incorporate travel time elasticities into the optimization to account for demand shifts from transit to cars, resulting from increases in transit travel time. We find that emissions reductions are moderated, but not eliminated, for relatively inelastic users. We consider two scenarios: the first is where only the agency faces an emissions budget; the second is where the entire city faces an emissions budget. In the latter scenario, the emissions reductions resulting from reductions in transit level of service are mitigated as users switch to automobile.

  17. Education and Change in Rich, Poor and National Minority Areas in China: Two Decades of Transition. CREATE Pathways to Access. Research Monograph No. 61

    ERIC Educational Resources Information Center

    Lewin, Keith M.; Lu, Wang

    2011-01-01

    This study traces education and change over two decades in three areas, Tongzhou on the periphery of Beijing chosen as one of the richest 300 counties in 1990; Ansai in Yan'an which was one of the poorest 300 counties and a famous base for the 8th Route Army at the end of the Long March, and Zhaojue a poor Yi national minority area in the…

  18. Evidence for the Direct Detection of the Thermal Spectrum of the Non-Transiting Hot Gas Giant HD 88133 b

    NASA Astrophysics Data System (ADS)

    Piskorz, Danielle; Crockett, Nathan R.; Lockwood, Alexandra; Benneke, Björn; Blake, Geoffrey A.; Barman, Travis S.; Bender, Chad F.; Bryan, Marta; Carr, John S.; Fischer, Debra; Howard, Andrew; Isaacson, Howard T.; Johnson, John A.

    2016-10-01

    We target the thermal emission spectrum of the non-transiting gas giant HD 88133 b with high-resolution near-infrared spectroscopy, by treating the planet and its host star as a spectroscopic binary. For sufficiently deep summed flux observations of the star and planet across multiple epochs, it is possible to resolve the signal of the hot gas giant's atmosphere compared to the brighter stellar spectrum, at a level consistent with the aggregate shot noise of the full data set. To do this, we first perform a principal component analysis to remove the contribution of the Earth's atmosphere to the observed spectra. Then, we use a cross-correlation analysis to tease out the spectra of the host star and HD 88133 b to determine its orbit and identify key sources of atmospheric opacity. In total, six epochs of Keck NIRSPEC L band observations and three epochs of Keck NIRSPEC K band observations of the HD 88133 system were obtained. Based on an analysis of the maximum likelihood curves calculated from the multi-epoch cross correlation of the full data set with two atmospheric models, we report the direct detection of the emission spectrum of the non-transiting exoplanet HD 88133 b and measure a radial projection of its Keplerian orbital velocity, its true mass, its orbital inclination, and dominant atmospheric species. This, combined with eleven years of radial velocity measurements of the system, provides the most up-to-date ephemeris for HD 88133.

  19. Quantum phase transition of a Bose gas in a lattice with a controlled number of atoms per site

    NASA Astrophysics Data System (ADS)

    Du, Xu

    2005-05-01

    We have studied the superfluid-Mott insulator quantum phase transition [1] of a gas of ^87Rb atoms in an optical lattice. We are able to prepare the gas with a controllable number of one, two, or three atoms per lattice site, as verified with photoassociation spectroscopy. We measure momentum distributions using standard time-of-flight imaging techniques. These are similar to those of ref. [1], and exhibit narrow peaks at moderate lattice strengths. We find that the width of these peaks increases for lattice heights greater than about 13 times the recoil energy [2], and we observe interesting differences in this behavior, depending on the number of atoms per site. The data suggest that the quantum phase transition occurs at higher lattice strength with larger site occupation. We acknowledge the support of this work by the R. A. Welch Foundation, The N. S. F., and the D.O.E. Quantum Optics Initiative. [1] Markus Greiner et al., Nature 415, 39 (2002). [2] Thilo St"oferle et al., Phys. Rev. Lett. 92, 130403 (2004).

  20. Sensor Transition Failure in the Hi-Flow Sampler™: Implications for Methane Emissions Estimates from Natural Gas Infrastructure

    NASA Astrophysics Data System (ADS)

    Howard, T.; Ferrara, T.

    2014-12-01

    Natural gas (NG) extraction and distribution are large anthropogenic sources of methane (CH4), and documenting the magnitude of leaks from NG infrastructure is a key step in reducing greenhouse gas emissions. The United States Environmental Protection Agency requires measurement and reporting of emissions of CH4 from NG transmission facilities. The Bacharach Hi-Flow Sampler (BHFS) is commonly used for quantifying CH4 emissions at transmission and other types of NG facilities. Here we document failure of the BHFS to transition from a catalytic oxidation sensor used to measure low NG (~5% or less) concentrations to a thermal conductivity sensor for higher concentrations (from ~5% to 100%), resulting in underestimation of NG emission rates, under one or more conditions: 1), calibration is more than ~2 weeks old; 2), firmware is out of date; or 3), the NG source is less than ~91% CH4. The extent to which this issue has affected recent emission studies is uncertain, but the analysis presented here suggests that BHFS sensor transition failure occurred during three recent field sampling programs.

  1. Auxiliary Gas Loading of Explosives and Their Sensitivity to DDT (Deflagration to Detonation Transition),

    DTIC Science & Technology

    1984-06-25

    RD-R147 659 AUXILIARY GAS LORDING OF EXPLOSIVES AND THEIR1/ SENSITIVITY TO DDT (DEFLARR (U) NAVAL SURFACE WEAPONS CENTER SILVER SPRING MD D PRICE ET...3 7.. AND THEIR11 SENITVITY TO DDT LnL Ll BY D. PRICE R. BERNECKER RESEARCH AND TECHNOLOGY DEPARTMENT ( 25JUNE 1984 C1 * Approved for public releass...AUXILIARY GAS LOADING OF EXPLOSIVES AND THEIR SENSITIVITY TO DDT S. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(e) S. CONTRACT OR GRANT NUMMER(a) Donna Price

  2. 76 FR 37175 - FY 2011 Discretionary Sustainability Funding Opportunity Transit Investments for Greenhouse Gas...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-24

    ... project; (2) Constructing or leasing clean fuel bus facilities or electrical recharging facilities and... With Discretionary Bus and Bus Facilities Program AGENCY: Federal Transit Administration (FTA), DOT... (TIGGER) program and Clean Fuels Grant program, augmented with Section 5309 Bus and Bus Facilities program...

  3. Schlieren Measurements of Buoyancy Effects on Flow Transition in Low-Density Gas Jets

    NASA Technical Reports Server (NTRS)

    Pasumarthi, Kasyap S.; Agrawal, Ajay K.

    2005-01-01

    The transition from laminar to turbulent flow in helium jets discharged into air was studied using Rainbow Schlieren Deflectometry technique. In particular, the effects of buoyancy on jet oscillations and flow transition length were considered. Experiments to simulate microgravity were conducted in the 2.2s drop tower at NASA Glenn Research Center. The jet Reynolds numbers varied from 800 to1200 and the jet Richardson numbers ranged between 0.01 and 0.004. Schlieren images revealed substantial variations in the flow structure during the drop. Fast Fourier Transform (FFT) analysis of the data obtained in Earth gravity experiments revealed the existence of a discrete oscillating frequency in the transition region, which matched the frequency in the upstream laminar regime. In microgravity, the transition occurred farther downstream indicating laminarization of the jet in the absence of buoyancy. The amplitude of jet oscillations was reduced by up to an order of magnitude in microgravity. Results suggest that jet oscillations were buoyancy induced and that the brief microgravity period may not be sufficient for the oscillations to completely subside.

  4. Schlieren Measurements of Buoyancy Effects on Flow Transition in Low-Density Gas Jets

    NASA Technical Reports Server (NTRS)

    Pasumarthi, Kasyap S.; Agrawal, Ajay K.

    2005-01-01

    The transition from laminar to turbulent flow in helium jets discharged into air was studied using Rainbow Schlieren Deflectometry technique. In particular, the effects of buoyancy on jet oscillations and flow transition length were considered. Experiments to simulate microgravity were conducted in the 2.2s drop tower at NASA Glenn Research Center. The jet Reynolds numbers varied from 800 to1200 and the jet Richardson numbers ranged between 0.01 and 0.004. Schlieren images revealed substantial variations in the flow structure during the drop. Fast Fourier Transform (FFT) analysis of the data obtained in Earth gravity experiments revealed the existence of a discrete oscillating frequency in the transition region, which matched the frequency in the upstream laminar regime. In microgravity, the transition occurred farther downstream indicating laminarization of the jet in the absence of buoyancy. The amplitude of jet oscillations was reduced by up to an order of magnitude in microgravity. Results suggest that jet oscillations were buoyancy induced and that the brief microgravity period may not be sufficient for the oscillations to completely subside.

  5. Water and greenhouse gas tradeoffs associated with a transition to a low carbon transportation system

    EPA Science Inventory

    Transportation fuels are heavily dominated by the use of petroleum, but concerns over oil depletion, energy security, and greenhouse gas emissions from petroleum combustion are driving the search for alternatives. As we look to shift away from petroleum-based transportation fuels...

  6. Water and greenhouse gas tradeoffs associated with a transition to a low carbon transportation system

    EPA Science Inventory

    Transportation fuels are heavily dominated by the use of petroleum, but concerns over oil depletion, energy security, and greenhouse gas emissions from petroleum combustion are driving the search for alternatives. As we look to shift away from petroleum-based transportation fuels...

  7. First and second sound in a two-dimensional harmonically trapped Bose gas across the Berezinskii–Kosterlitz–Thouless transition

    SciTech Connect

    Liu, Xia-Ji Hu, Hui

    2014-12-15

    We theoretically investigate first and second sound of a two-dimensional (2D) atomic Bose gas in harmonic traps by solving Landau’s two-fluid hydrodynamic equations. For an isotropic trap, we find that first and second sound modes become degenerate at certain temperatures and exhibit typical avoided crossings in mode frequencies. At these temperatures, second sound has significant density fluctuation due to its hybridization with first sound and has a divergent mode frequency towards the Berezinskii–Kosterlitz–Thouless (BKT) transition. For a highly anisotropic trap, we derive the simplified one-dimensional hydrodynamic equations and discuss the sound-wave propagation along the weakly confined direction. Due to the universal jump of the superfluid density inherent to the BKT transition, we show that the first sound velocity exhibits a kink across the transition. These predictions might be readily examined in current experimental setups for 2D dilute Bose gases with a sufficiently large number of atoms, where the finite-size effect due to harmonic traps is relatively weak.

  8. Atomic-to-molecular gas phase transition triggered by the radio jet in Centaurus A

    NASA Astrophysics Data System (ADS)

    Salomé, Q.; Salomé, P.; Combes, F.; Hamer, S.

    2016-10-01

    NGC 5128 (Centaurus A) is one of the best example to study AGN-feedback in the local Universe. At 13.5 kpc from the galaxy, optical filaments with recent star formation are lying along the radio-jet direction. We used the Atacama Pathfinder EXperiment (APEX) to map the CO(2-1) emission all along the filaments structure. Molecular gas mass of (8.2 ± 0.5) × 107 M⊙ was found over the 4.2 kpc-structure which represents about 3% of the total gas mass of the NGC 5128 cold gas content. Two dusty mostly molecular structures are identified, following the optical filaments. The region corresponds to the crossing of the radio jet with the northern H i shell, coming from a past galaxy merger. One filament is located at the border of the H i shell, while the other is entirely molecular, and devoid of H i gas. The molecular mass is comparable to the H i mass in the shell, suggesting a scenario where the atomic gas was shocked and transformed in molecular clouds by the radio jet. Comparison with combined far-IR Herschel and UV GALEX estimation of star formation rates in the same regions leads to depletion times of more than 10 Gyr. The filaments are thus less efficient than discs in converting molecular gas into stars. Kinetic energy injection triggered by shocks all along the jet and gas interface is a possible process that appears to be consistent with MUSE line ratio diagnostics derived in a smaller region of the northern filaments. Whether the AGN is the sole origin of this energy input and what is the dominant (mechanical vs. radiative) mode for this process is however still to be investigated. This publication is based on data acquired with the Atacama Pathfinder Experiment (APEX) under programme ID 096.B-0892.The reduced APEX spectra (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A65

  9. Fine cohesive powders in rotating drums: Transition from rigid-plastic flow to gas-fluidized regime

    NASA Astrophysics Data System (ADS)

    Castellanos, A.; Valverde, J. M.; Quintanilla, M. A.

    2002-06-01

    We investigate the dynamics of fine cohesive powders inside rotating drums. We show that these powders may be fluidized due to entrapment of ambient gas, and we determine the onset of fluidization. Experimental measurements on the bed expansion as a function of the rotation velocity have been performed. Drums of different diameters and fine powders of varying cohesiveness have been tested. We show that (i) fine powders transit directly from a rigid-plastic state to a gas-fluidized state in accordance with the flow regime boundaries predicted elsewhere [A. Castellanos et al., Phys. Rev. Lett. 82, 1156 (1999)], (ii) the onset of fluidization in the rotating drum is determined by the ratio of the powder kinetic energy per unit volume to its tensile strength, and (iii) once the powder is completely fluidized the average interstitial gas velocity increases proportionally to the rotation velocity. The last two results imply that the required velocity to fluidize a powder, ωR (ω angular velocity, R radius of the drum), must increase as the square root of its tensile strength, and this has been confirmed by independent measurements and estimations.

  10. Investigating the Structural Compaction of Biomolecules Upon Transition to the Gas-Phase Using ESI-TWIMS-MS.

    PubMed

    Devine, Paul W A; Fisher, Henry C; Calabrese, Antonio N; Whelan, Fiona; Higazi, Daniel R; Potts, Jennifer R; Lowe, David C; Radford, Sheena E; Ashcroft, Alison E

    2017-05-08

    Collision cross-section (CCS) measurements obtained from ion mobility spectrometry-mass spectrometry (IMS-MS) analyses often provide useful information concerning a protein's size and shape and can be complemented by modeling procedures. However, there have been some concerns about the extent to which certain proteins maintain a native-like conformation during the gas-phase analysis, especially proteins with dynamic or extended regions. Here we have measured the CCSs of a range of biomolecules including non-globular proteins and RNAs of different sequence, size, and stability. Using traveling wave IMS-MS, we show that for the proteins studied, the measured CCS deviates significantly from predicted CCS values based upon currently available structures. The results presented indicate that these proteins collapse to different extents varying on their elongated structures upon transition into the gas-phase. Comparing two RNAs of similar mass but different solution structures, we show that these biomolecules may also be susceptible to gas-phase compaction. Together, the results suggest that caution is needed when predicting structural models based on CCS data for RNAs as well as proteins with non-globular folds. Graphical Abstract ᅟ.

  11. Investigating the Structural Compaction of Biomolecules Upon Transition to the Gas-Phase Using ESI-TWIMS-MS

    NASA Astrophysics Data System (ADS)

    Devine, Paul W. A.; Fisher, Henry C.; Calabrese, Antonio N.; Whelan, Fiona; Higazi, Daniel R.; Potts, Jennifer R.; Lowe, David C.; Radford, Sheena E.; Ashcroft, Alison E.

    2017-09-01

    Collision cross-section (CCS) measurements obtained from ion mobility spectrometry-mass spectrometry (IMS-MS) analyses often provide useful information concerning a protein's size and shape and can be complemented by modeling procedures. However, there have been some concerns about the extent to which certain proteins maintain a native-like conformation during the gas-phase analysis, especially proteins with dynamic or extended regions. Here we have measured the CCSs of a range of biomolecules including non-globular proteins and RNAs of different sequence, size, and stability. Using traveling wave IMS-MS, we show that for the proteins studied, the measured CCS deviates significantly from predicted CCS values based upon currently available structures. The results presented indicate that these proteins collapse to different extents varying on their elongated structures upon transition into the gas-phase. Comparing two RNAs of similar mass but different solution structures, we show that these biomolecules may also be susceptible to gas-phase compaction. Together, the results suggest that caution is needed when predicting structural models based on CCS data for RNAs as well as proteins with non-globular folds. [Figure not available: see fulltext.

  12. Investigating the Structural Compaction of Biomolecules Upon Transition to the Gas-Phase Using ESI-TWIMS-MS

    NASA Astrophysics Data System (ADS)

    Devine, Paul W. A.; Fisher, Henry C.; Calabrese, Antonio N.; Whelan, Fiona; Higazi, Daniel R.; Potts, Jennifer R.; Lowe, David C.; Radford, Sheena E.; Ashcroft, Alison E.

    2017-05-01

    Collision cross-section (CCS) measurements obtained from ion mobility spectrometry-mass spectrometry (IMS-MS) analyses often provide useful information concerning a protein's size and shape and can be complemented by modeling procedures. However, there have been some concerns about the extent to which certain proteins maintain a native-like conformation during the gas-phase analysis, especially proteins with dynamic or extended regions. Here we have measured the CCSs of a range of biomolecules including non-globular proteins and RNAs of different sequence, size, and stability. Using traveling wave IMS-MS, we show that for the proteins studied, the measured CCS deviates significantly from predicted CCS values based upon currently available structures. The results presented indicate that these proteins collapse to different extents varying on their elongated structures upon transition into the gas-phase. Comparing two RNAs of similar mass but different solution structures, we show that these biomolecules may also be susceptible to gas-phase compaction. Together, the results suggest that caution is needed when predicting structural models based on CCS data for RNAs as well as proteins with non-globular folds.

  13. Atom probe study of Cu-poor to Cu-rich transition during Cu(In,Ga)Se{sub 2} growth

    SciTech Connect

    Couzinie-Devy, F.; Cadel, E.; Pareige, P.; Barreau, N.; Arzel, L.

    2011-12-05

    Atomic scale chemistry of polycrystalline Cu(In,Ga)Se{sub 2} (CIGSe) thin film has been characterized at key points of the 3-stage process using atom probe tomography. 3D atom distributions have been reconstructed when the layer is Cu-poor ([Cu]/([Ga] + [In]) < 1), Cu-rich ([Cu]/([Ga] + [In]) > 1), and at the end of the process. Particular attention has been devoted to grain boundary composition and Na atomic distribution within the CIGSe layer. Significant variation of composition is highlighted during the growing process, providing fundamental information helping the understanding of high efficiency CIGSe formation.

  14. HAT-P-24b: AN INFLATED HOT JUPITER ON A 3.36 DAY PERIOD TRANSITING A HOT, METAL-POOR STAR

    SciTech Connect

    Kipping, D. M.; Bakos, G. A.; Hartman, J.; Torres, G.; Latham, D. W.; Noyes, R. W.; Beky, B.; Perumpilly, G.; Esquerdo, G. A.; Sasselov, D. D.; Stefanik, R. P.; Shporer, A.; Kovacs, Geza; Howard, A. W.; Marcy, G. W.; Fischer, D. A.; Johnson, J. A.; Lazar, J.; Papp, I.; Sari, P.

    2010-12-20

    We report the discovery of HAT-P-24b, a transiting extrasolar planet orbiting the moderately bright V = 11.818 F8 dwarf star GSC 0774-01441, with a period P = 3.3552464 {+-} 0.0000071 days, transit epoch T{sub c} = 2455216.97669 {+-} 0.00024 (BJD)11, and transit duration 3.653 {+-} 0.025 hr. The host star has a mass of 1.191 {+-} 0.042 M{sub sun}, radius of 1.317 {+-} 0.068 R{sub sun}, effective temperature 6373 {+-} 80 K, and a low metallicity of [Fe/H] = -0.16 {+-} 0.08. The planetary companion has a mass of 0.681 {+-} 0.031 M{sub J} and radius of 1.243 {+-} 0.072 R{sub J} yielding a mean density of 0.439 {+-} 0.069 g cm{sup -3}. By repeating our global fits with different parameter sets, we have performed a critical investigation of the fitting techniques used for previous Hungarian-made Automated Telescope planetary discoveries. We find that the system properties are robust against the choice of priors. The effects of fixed versus fitted limb darkening are also examined. HAT-P-24b probably maintains a small eccentricity of e = 0.052{sup +0.022}{sub -0.017}, which is accepted over the circular orbit model with false alarm probability 5.8%. In the absence of eccentricity pumping, this result suggests that HAT-P-24b experiences less tidal dissipation than Jupiter. Due to relatively rapid stellar rotation, we estimate that HAT-P-24b should exhibit one of the largest known Rossiter-McLaughlin effect amplitudes for an exoplanet ({Delta}V{sub RM} {approx_equal} 95 m s{sup -1}) and thus a precise measurement of the sky-projected spin-orbit alignment should be possible.

  15. Central metabolism in Mycobacterium smegmatis during the transition from O2-rich to O2-poor conditions as studied by isotopomer-assisted metabolite analysis.

    PubMed

    Tang, Yinjie J; Shui, Wenqing; Myers, Samuel; Feng, Xueyang; Bertozzi, Carolyn; Keasling, Jay D

    2009-08-01

    Isotopomer-assisted metabolite analysis was used to investigate the central metabolism of Mycobacterium smegmatis and its transition from normal growth to a non-replicating state under a hypoxic environment. Tween 80 significantly promoted aerobic growth by improving O(2) transfer, while only small amount was degraded and metabolized via the TCA cycle for biomass synthesis. As the bacillus encountered hypoxic stress, isotopomer analysis suggested: (1) isocitrate lyase activity increased, which further induced glyoxylate pathway and glycine dehydrogenase for replenishing NAD(+); (2) the relative amount of acetyl-CoA entering the TCA cycle was doubled, whereas little entered the glycolytic and pentose phosphate pathways.

  16. Condensate fraction in a 2D Bose gas measured across the Mott-insulator transition.

    PubMed

    Spielman, I B; Phillips, W D; Porto, J V

    2008-03-28

    We realize a single-band 2D Bose-Hubbard system with Rb atoms in an optical lattice and measure the condensate fraction as a function of lattice depth, crossing from the superfluid to the Mott-insulating phase. We quantitatively identify the location of the superfluid to normal transition by observing when the condensed fraction vanishes. Our measurement agrees with recent quantum Monte Carlo calculations for a finite-sized 2D system to within experimental uncertainty.

  17. Equilibrium and non-equilibrium properties of a relativistic gas at the transition temperature

    NASA Astrophysics Data System (ADS)

    Chacón-Acosta, Guillermo

    2016-11-01

    The Jüttner distribution function for equilibrium relativistic fluids has two well-known limits, the non-relativistic limit at low temperatures and ultra-relativistic limit for high temperatures. Recently, the description of this transition in velocity space in the system, from a gaussian to a bimodal distribution was made by Mendoza et al. Physically, it is a transition between a regime where the relativistic energy is dominated by kinetic to another where the rest energy dominates. It has been found that the critical temperature at which the relativistic corrections becomes relevant, depends just on the dimension of the system, this allowed a description in terms of the theory of critical points (Montakhab et al.). In this contribution a review of the thermodynamic quantities that are only dependent on the ratio between temperature and critical temperature, and the dimension is made. We will also analyze the effects of critical temperature on dissipative processes in simple special relativistic fluids. Particularly, purely relativistic terms that are usually proportional to the number density gradient are studied. The transport coefficients can be written in terms of the transition temperature, this will allow us to identify the lower order relativistic effects just in terms of the dimension of the system.

  18. Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms.

    PubMed

    Greiner, Markus; Mandel, Olaf; Esslinger, Tilman; Hänsch, Theodor W; Bloch, Immanuel

    2002-01-03

    For a system at a temperature of absolute zero, all thermal fluctuations are frozen out, while quantum fluctuations prevail. These microscopic quantum fluctuations can induce a macroscopic phase transition in the ground state of a many-body system when the relative strength of two competing energy terms is varied across a critical value. Here we observe such a quantum phase transition in a Bose-Einstein condensate with repulsive interactions, held in a three-dimensional optical lattice potential. As the potential depth of the lattice is increased, a transition is observed from a superfluid to a Mott insulator phase. In the superfluid phase, each atom is spread out over the entire lattice, with long-range phase coherence. But in the insulating phase, exact numbers of atoms are localized at individual lattice sites, with no phase coherence across the lattice; this phase is characterized by a gap in the excitation spectrum. We can induce reversible changes between the two ground states of the system.

  19. The transition from silicon to gas detection media in nuclear physics

    NASA Astrophysics Data System (ADS)

    Pollacco, Emanuel C.

    2016-06-01

    Emerging radioactive beams and multi petawatt laser facilities are sturdily transforming our base concepts in instruments in nuclear physics. The changes are fuelled by studies of nuclei close to the drip-line or exotic reactions. This physics demands high luminosity, wide phase space cover with good resolution in energy, time, position and sampled waveform. By judiciously modifying the micro-world of the particle or space physics instruments (Double Sided Strip Si Detectors, Micro-Pattern Gas Amplifiers, microelectronics), we are on the path to initiate dream experiments. In the following a brief status in the domain is reported for selected instruments that highlight the present trends with silicon and the growing shift towards gas media for charged particle detection.

  20. Is there evidence for a liquid-gas phase transition in nuclear matter?

    SciTech Connect

    Hirsch, A.S.; EOS Collaboration

    1994-09-01

    The multifragmentation of gold nuclei at 1 GeV/nucleon has been studied using reverse kinematics. The moments of the resulting charged fragment distribution have been analyzed using methods borrowed from percolation theory. These moments provide clear evidence for critical behavior occurring in a system of about 200 nucleons. The critical exponents extracted from the data are close to those of liquid-gas systems.

  1. HAT-P-24b: An Inflated Hot Jupiter on a 3.36 Day Period Transiting a Hot, Metal-poor Star

    NASA Astrophysics Data System (ADS)

    Kipping, D. M.; Bakos, G. Á.; Hartman, J.; Torres, G.; Shporer, A.; Latham, D. W.; Kovács, Géza; Noyes, R. W.; Howard, A. W.; Fischer, D. A.; Johnson, J. A.; Marcy, G. W.; Béky, B.; Perumpilly, G.; Esquerdo, G. A.; Sasselov, D. D.; Stefanik, R. P.; Lázár, J.; Papp, I.; Sári, P.

    2010-12-01

    We report the discovery of HAT-P-24b, a transiting extrasolar planet orbiting the moderately bright V = 11.818 F8 dwarf star GSC 0774-01441, with a period P = 3.3552464 ± 0.0000071 days, transit epoch Tc = 2455216.97669 ± 0.00024 (BJD)11, and transit duration 3.653 ± 0.025 hr. The host star has a mass of 1.191 ± 0.042 M sun, radius of 1.317 ± 0.068 R sun, effective temperature 6373 ± 80 K, and a low metallicity of [Fe/H] = -0.16 ± 0.08. The planetary companion has a mass of 0.681 ± 0.031 M J and radius of 1.243 ± 0.072 R J yielding a mean density of 0.439 ± 0.069 g cm-3. By repeating our global fits with different parameter sets, we have performed a critical investigation of the fitting techniques used for previous Hungarian-made Automated Telescope planetary discoveries. We find that the system properties are robust against the choice of priors. The effects of fixed versus fitted limb darkening are also examined. HAT-P-24b probably maintains a small eccentricity of e = 0.052+0.022 -0.017, which is accepted over the circular orbit model with false alarm probability 5.8%. In the absence of eccentricity pumping, this result suggests that HAT-P-24b experiences less tidal dissipation than Jupiter. Due to relatively rapid stellar rotation, we estimate that HAT-P-24b should exhibit one of the largest known Rossiter-McLaughlin effect amplitudes for an exoplanet (ΔV RM ~= 95 m s-1) and thus a precise measurement of the sky-projected spin-orbit alignment should be possible. Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Keck time has been granted by NOAO and NASA.

  2. The effects of neutral gas heating on H mode transition and maintenance currents in a 13.56 MHz planar coil inductively coupled plasma reactor

    SciTech Connect

    Jayapalan, Kanesh K.; Chin, Oi-Hoong

    2012-09-15

    The H mode transition and maintenance currents in a 13.56 MHz laboratory 6 turn planar coil inductively coupled plasma (ICP) reactor are simulated for low pressure argon discharge range of 0.02-0.3 mbar with neutral gas heating and at ambient temperature. An experimentally fitted 3D power evolution plot for 0.02 mbar argon pressure is also shown to visualize the effects of hysteresis in the system. Comparisons between simulation and experimental measurements show good agreement in the pressure range of 0.02-0.3 mbar for transition currents and 0.02-0.1 mbar for maintenance currents only when neutral gas heating is considered. This suggests that neutral gas heating plays a non-negligible role in determining the mode transition points of a rf ICP system.

  3. Long non-coding RNA ATB promotes growth and epithelial-mesenchymal transition and predicts poor prognosis in human prostate carcinoma

    PubMed Central

    XU, SONG; YI, XIAO-MING; TANG, CHAO-PENG; GE, JING-PING; ZHANG, ZHENG-YU; ZHOU, WEN-QUAN

    2016-01-01

    Long non-coding RNAs (lncRNAs) have been identified to be critical mediators in various tumors associated with cancer progression. Long non-coding RNA activated by TGF-β (lncRNA-ATB) is a stimulator of epithelial-mesenchymal transition (EMT) and serves as a novel prognostic biomarker for hepatocellular carcinoma. However, the biological role and clinical significance of lncRNA-ATB in human prostate cancer have yet to be fully elucidated. The present study was designed to explore the expression of lncRNA-ATB in human prostate cancer patients and the role of lncRNA-ATB in prostate cancer cells. We showed that lncRNA-ATB expression was significantly upregulated in tumor tissues in patients with prostate cancer in comparison with adjacent non-tumor tissues. Further analysis indicted that high lncRNA-ATB expression may be an independent prognostic factor for biochemical recurrence (BCR)-free survival in prostate cancer patients. Overexpression of lncRNA-ATB promoted, and knockdown of lncRNA-ATB inhibited the growth of prostate cancer cells via regulations of cell cycle regulatory protein expression levels. In addition, lncRNA-ATB stimulated epithelial-mesenchymal transition (EMT) associated with ZEB1 and ZNF217 expression levels via ERK and PI3K/AKT signaling pathways. These results indicated that lncRNA-ATB may be considered as a new predictor in the clinical prognosis of patients with prostate cancer. Overexpression of lncRNA-ATB exerts mitogenic and EMT effects of prostate cancer via activation of ERK and PI3K/AKT signaling pathways. PMID:27176634

  4. Induced Interactions and the Superfluid Transition Temperature in a Three-Component Fermi Gas

    SciTech Connect

    Martikainen, J.-P.; Kinnunen, J. J.; Toermae, P.; Pethick, C. J.

    2009-12-31

    We study many-body contributions to the effective interaction between fermions in a three-component Fermi mixture. We find that effective interactions induced by the third component can lead to a phase diagram different from that predicted if interactions with the third component are neglected. As a result, in a confining potential a superfluid shell structure can arise even for equal populations of the components. We also find a critical temperature for the BCS transition in a {sup 6}Li mixture which can deviate strongly from the one in a weakly interacting two-component system.

  5. Transport of a Bose gas in 1D disordered lattices at the fluid-insulator transition.

    PubMed

    Tanzi, Luca; Lucioni, Eleonora; Chaudhuri, Saptarishi; Gori, Lorenzo; Kumar, Avinash; D'Errico, Chiara; Inguscio, Massimo; Modugno, Giovanni

    2013-09-13

    We investigate the momentum-dependent transport of 1D quasicondensates in quasiperiodic optical lattices. We observe a sharp crossover from a weakly dissipative regime to a strongly unstable one at a disorder-dependent critical momentum. In the limit of nondisordered lattices the observations suggest a contribution of quantum phase slips to the dissipation. We identify a set of critical disorder and interaction strengths for which such critical momentum vanishes, separating a fluid regime from an insulating one. We relate our observation to the predicted zero-temperature superfluid-Bose glass transition.

  6. Infrared Spectroscopy of Transition Metal-Molecular interactions in the Gas Phase

    SciTech Connect

    Duncan, Michael A.

    2008-11-14

    Transition metal-molecular complexes produced in a molecular beam are mass-selected and studied with infrared laser photodissociation spectroscopy. Metal complexes with carbon monoxide, carbon dioxide, nitrogen, water, acetylene or benzene are studied for a variety of metals. The number and intensity of infrared active bands are compared to the predictions of density functional theory calculations to derive structures, spin states and coordination numbers in these systems. These studied provide new insights into subtle details of metal-molecular interactions important in heterogeneous catalysis, metal-ligand bonding and metal ion solvation.

  7. Endohedral nitrogen storage in carbon fullerene structures: physisorption to chemisorption transition with increasing gas pressure.

    PubMed

    Barajas-Barraza, R E; Guirado-López, R A

    2009-06-21

    We present extensive pseudopotential density functional theory (DFT) calculations in order to analyze the structural properties and chemical reactivity of nitrogen molecules confined in spheroidal (C(82)) and tubelike (C(110)) carbon fullerene structures. For a small number of encapsulated nitrogens, the N(2) species exist in a nonbonded state within the cavities and form well defined molecular conformations such as linear chains, zigzag arrays, as well as both spheroidal and tubular configurations. However, with increasing the number of stored molecules, the interaction among the confined nitrogens as well as between the N(2) species and the fullerene wall is not always mainly repulsive. Actually, at high densities of the encapsulated gas, we found both adsorption of N(2) to the inner carbon surface together with the formation of (N(2))(m) molecular clusters. Total energy DFT calculations reveal that the shape of the interaction potential of a test molecule moving within the carbon cavities strongly varies with the number and proximity of the coadsorbed N(2) from being purely repulsive to having short-range attractive contributions close to the inner wall. In particular, the latter are always found when a group of closely spaced nitrogens is located near the carbon cage (a fact that will naturally occur at high densities of the encapsulated gas), inducing the formation of covalent bonds between the N(2) and the fullerene network. Interestingly, in some cases, the previous nitrogen adsorption to the inner surface is reversible by reducing the gas pressure. The calculated average density of states of our considered carbon compounds reveals the appearance of well defined features that clearly reflect the occurring structural changes and modifications in the adsorption properties in the systems. Our results clearly underline the crucial role played by confinement effects on the reactivity of our endohedral compounds, define this kind of materials as nonideal

  8. Complexation of diazaperylene and bisisoquinoline with transition metal ions in the gas phase studied by electrospray ionization mass spectrometry.

    PubMed

    Starke, Ines; Kammer, Stefan; Grunwald, Nicolas; Schilde, Uwe; Holdt, Hans-Jürgen; Kleinpeter, Erich

    2008-01-01

    The complex formation of the ligands 1,12-diazaperylene (dap), 1,1'-bisisoquinoline (bis), 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) with transition metal ions (M = Fe, Co, Ni, Cu, Zn, Ru, Os, Re, Pd, Pt, Ag and Cd) in the gas phase has been studied by electrospray ionization mass spectrometry. With the exception of Ru, Os, Fe, Ni and Cu, singly charged complexes [MLn](+) (n = 1,2) were observed. The complexes of dap and bis with Ru, Os, Fe and Ni ions, and the mixed ligand complexes with bpy and phen, are preferably of the doubly charged type [ML3]2+. In addition, collision-induced dissociation (CID) measurements were employed to evaluate the relative stabilities of these complexes. The CID experiments of mixed-ligand complexes which contain both dap and phen or dap and bpy exhibit preferential elimination of bpy, indicating that bpy is a weaker ligand than phen and dap.

  9. Evidence for the Direct Detection of the Thermal Spectrum of the Non-Transiting Hot Gas Giant HD 88133 b

    NASA Astrophysics Data System (ADS)

    Piskorz, Danielle; Benneke, Björn; Crockett, Nathan R.; Lockwood, Alexandra C.; Blake, Geoffrey A.; Barman, Travis S.; Bender, Chad F.; Bryan, Marta L.; Carr, John S.; Fischer, Debra A.; Howard, Andrew W.; Isaacson, Howard; Johnson, John A.

    2016-12-01

    We target the thermal emission spectrum of the non-transiting gas giant HD 88133 b with high-resolution near-infrared spectroscopy, by treating the planet and its host star as a spectroscopic binary. For sufficiently deep summed flux observations of the star and planet across multiple epochs, it is possible to resolve the signal of the hot gas giant’s atmosphere compared to the brighter stellar spectrum, at a level consistent with the aggregate shot noise of the full data set. To do this, we first perform a principal component analysis to remove the contribution of the Earth’s atmosphere to the observed spectra. Then, we use a cross-correlation analysis to tease out the spectra of the host star and HD 88133 b to determine its orbit and identify key sources of atmospheric opacity. In total, six epochs of Keck NIRSPEC L-band observations and three epochs of Keck NIRSPEC K-band observations of the HD 88133 system were obtained. Based on an analysis of the maximum likelihood curves calculated from the multi-epoch cross-correlation of the full data set with two atmospheric models, we report the direct detection of the emission spectrum of the non-transiting exoplanet HD 88133 b and measure a radial projection of the Keplerian orbital velocity of 40 ± 15 km s-1, a true mass of {1.02}-0.28+0.61{M}{{J}}, a nearly face-on orbital inclination of {15}-5+6^\\circ , and an atmosphere opacity structure at high dispersion dominated by water vapor. This, combined with 11 years of radial velocity measurements of the system, provides the most up-to-date ephemeris for HD 88133.

  10. Usefulness of right-to-left shunting and poor exercise gas exchange for predicting prognosis in patients with pulmonary arterial hypertension.

    PubMed

    Oudiz, Ronald J; Midde, Raghu; Hovenesyan, Arsen; Sun, Xing-Guo; Roveran, Giorgio; Hansen, James E; Wasserman, Karlman

    2010-04-15

    We hypothesized that the longitudinal changes in peak oxygen uptake, ventilatory efficiency, and exercise-induced right-to-left shunting in patients with pulmonary arterial hypertension (PAH) would predict outcomes better than baseline measurements alone. Patients with PAH die prematurely. Identifying prognostic markers is critical for treating patients with PAH; however, longitudinal prognostic information of PAH is limited. We enrolled 103 patients with PAH into a long-term, prospective outcome study using serial cardiopulmonary exercise testing to measure the peak oxygen uptake, ventilatory efficiency (ratio of ventilation to carbon dioxide output at the anaerobic threshold), right-to-left shunting, and other factors in patients treated with optimal therapy. The patients were followed up for a mean of 4.7 years. During the study period, 20 patients died, and 3 underwent lung transplantation. The baseline peak oxygen uptake and ventilatory efficiency was 0.79 L/min and 49 (normal <34), respectively, reflecting severe disease. Poorer ventilatory efficiency and greater New York Heart Association classification were associated with poor outcome at baseline and at follow-up. On multivariate analysis, the persistence or development of an exercise-induced right-to-left shunt strongly predicted death or transplantation (p <0.0001), independent of the hemodynamics and all other exercise measures, including peak oxygen uptake and ventilatory efficiency. The absence of a shunt at baseline was associated with a 20% rate of nonsurvival, which decreased to 7% at follow-up. A poorer ventilatory efficiency appeared to be associated with a poor outcome in patients without a shunt. In conclusion, a persistent exercise-induced right-to-left shunt and poor ventilatory efficiency were highly predictive of poor outcomes in patients with pulmonary arterial hypertension.

  11. MiR-429 is linked to metastasis and poor prognosis in renal cell carcinoma by affecting epithelial-mesenchymal transition.

    PubMed

    Machackova, Tana; Mlcochova, Hana; Stanik, Michal; Dolezel, Jan; Fedorko, Michal; Pacik, Dalibor; Poprach, Alexandr; Svoboda, Marek; Slaby, Ondrej

    2016-11-01

    MicroRNAs (miRNAs) have been proven to be important oncogenes and tumor suppressors in wide range of cancers, including renal cell carcinoma (RCC). In our study, we evaluated miRNA-429 as potential diagnostic/prognostic biomarker in 172 clear cell RCC patients and as a potential regulator of epithelial-mesenchymal transition (EMT) in vitro. We demonstrated that miR-429 is down-regulated in tumor tissue samples (P < 0.0001) and is significantly associated with cancer metastasis (P < 0.0001), shorter disease-free (P = 0.0105), and overall survival (P = 0.0020). In addition, ectopic expression of miR-429 in 786-0 RCC cells followed by TGF-β treatment led to increase in the levels of E-cadherin expression (P < 0.0001) and suppression of cellular migration (P < 0.0001) in comparison to TGF-β-treated controls. Taken together, our findings suggest that miR-429 may serve as promising diagnostic and prognostic biomarker in RCC patients. We further suggest that miR-429 has a capacity to inhibit loss of E-cadherin in RCC cells undergoing EMT and consequently attenuate their motility.

  12. Overexpression of forkhead Box C2 promotes tumor metastasis and indicates poor prognosis in colon cancer via regulating epithelial-mesenchymal transition.

    PubMed

    Li, Qingguo; Wu, Jitao; Wei, Ping; Xu, Ye; Zhuo, Changhua; Wang, Yuwei; Li, Dawei; Cai, Sanjun

    2015-01-01

    Forkhead box protein C2 (FOXC2) plays a vital role in carcinogenesis; however, its significance and prognostic value in colon cancer remain unclear. In this study, FOXC2 expression was analyzed in a tissue microarray (TMA) containing 185 samples of primary colon cancer tumor samples and in human colon cancer cell lines. The effect of FOXC2 on cell proliferation, tumorigenesis, and metastasis was examined in vitro and in vivo. FOXC2 was overexpressed in human colon cancer cells and tissues, and correlated with colon cancer progression and patient survival. Functional study demonstrated that FOXC2 promoted cell growth, cell migration, and tumor formation in nude mice, whereas knockdown of FOXC2 by short hairpin RNA (shRNAs) significantly suppressed cell growth, cell migration and tumor formation. Further study found that FOXC2 enhanced AKT activity with subsequent GSK-3β phosphorylation and Snail stabilization, and then induced epithelial-mesenchymal transition (EMT) and promoted tumor invasion and metastasis. Collectively, FOXC2 promotes colon cancer metastasis by facilitating EMT and acts as a potential prognostic factor and therapeutic target in colon cancer.

  13. Upregulation of long noncoding RNA zinc finger antisense 1 enhances epithelial-mesenchymal transition in vitro and predicts poor prognosis in glioma.

    PubMed

    Lv, Qiao-Li; Chen, Shu-Hui; Zhang, Xue; Sun, Bao; Hu, Lei; Qu, Qiang; Huang, Yuan-Tao; Wang, Gui-Hua; Liu, Yan-Ling; Zhang, Ying-Ying; Zhou, Hong-Hao

    2017-03-01

    Increasing evidence indicates that long noncoding RNAs play important roles in development and progression of various cancers. Zinc finger antisense 1 is a novel long noncoding RNA whose clinical significance, biological function, and underlying mechanism are still undetermined in glioma. In this study, we reported that zinc finger antisense 1 expression was markedly upregulated in glioma and tightly correlated with clinical stage. Moreover, patients with high zinc finger antisense 1 expression had shorter survival. Multivariate Cox regression analysis provided a clue that, probably, zinc finger antisense 1 level could serve as an independent prognostic factor for glioma. Functionally, zinc finger antisense 1 acted as an oncogene in glioma because its knockdown could promote apoptosis and significantly inhibit cell proliferation, migration, and invasion. Furthermore, zinc finger antisense 1 silencing could result in cell cycle arrest at the G0/G1 phase and correspondingly decrease the percentage of S phase cells in both U87 and U251 cell lines. Moreover, it was found that silenced zinc finger antisense 1 could impair migration and invasion by inhibiting the epithelial-mesenchymal transition through reducing the expression of MMP2, MMP9, N-cadherin, Integrin β1, ZEB1, Twist, and Snail as well as increasing E-cadherin level in glioma. Taken together, our data identified that zinc finger antisense 1 might act as a valuable prognostic biomarker and potential therapeutic target for glioma.

  14. CCR7 enhances TGF-β1-induced epithelial-mesenchymal transition and is associated with lymph node metastasis and poor overall survival in gastric cancer

    PubMed Central

    Qin, Jie; Chen, Long; Liu, Xinzhou; Xu, Pingping; Wang, Fei; Xiao, Honglei; Zhou, Shuang; Gao, Qiang; Liu, Binbin; Sun, Yihong; Liang, Chunmin

    2015-01-01

    CCR7 is a G protein-coupled chemokine receptor. In this study, we used immunohistochemistry with tissue microarrays to measure CCR7 expression in tumor specimens from 122 patients with gastric cancer. We show that CCR7 expression is associated with lymph node metastasis (P = 0.022) and overall survival (OS; P = 0.025), and is an independent factor associated with poorer overall survival (P = 0.032). The CCR7 mechanism was predicted based on bioinformatic analysis and verified in gastric cancer cell lines and primary tumor samples. The data show that CCR7 contributes to TGF-β1-induced epithelial-mesenchymal transition (EMT) and that the effects of TGF-β1 are inhibited by a CCR7 neutralizing antibody or a NF-κB inhibitor. Increased TGF-β1 expression was accompanied by nuclear localization of NF-κB-p65 and higher levels of the mesenchymal marker vimentin in human gastric cancer samples. We conclude that the CCR7 axis mediates TGF-β1-induced EMT via crosstalk with NF-κB signaling, facilitating lymph node metastasis and poorer overall survival in patients with gastric cancer. These findings suggest CCR7 is a novel prognostic indicator and a potential target for gastric cancer therapy. PMID:26176983

  15. CCR7 enhances TGF-β1-induced epithelial-mesenchymal transition and is associated with lymph node metastasis and poor overall survival in gastric cancer.

    PubMed

    Ma, Huiying; Gao, Lingling; Li, Shichao; Qin, Jie; Chen, Long; Liu, Xinzhou; Xu, Pingping; Wang, Fei; Xiao, Honglei; Zhou, Shuang; Gao, Qiang; Liu, Binbin; Sun, Yihong; Liang, Chunmin

    2015-09-15

    CCR7 is a G protein-coupled chemokine receptor. In this study, we used immunohistochemistry with tissue microarrays to measure CCR7 expression in tumor specimens from 122 patients with gastric cancer. We show that CCR7 expression is associated with lymph node metastasis (P = 0.022) and overall survival (OS; P = 0.025), and is an independent factor associated with poorer overall survival (P = 0.032). The CCR7 mechanism was predicted based on bioinformatic analysis and verified in gastric cancer cell lines and primary tumor samples. The data show that CCR7 contributes to TGF-β1-induced epithelial-mesenchymal transition (EMT) and that the effects of TGF-β1 are inhibited by a CCR7 neutralizing antibody or a NF-κB inhibitor. Increased TGF-β1 expression was accompanied by nuclear localization of NF-κB-p65 and higher levels of the mesenchymal marker vimentin in human gastric cancer samples. We conclude that the CCR7 axis mediates TGF-β1-induced EMT via crosstalk with NF-κB signaling, facilitating lymph node metastasis and poorer overall survival in patients with gastric cancer. These findings suggest CCR7 is a novel prognostic indicator and a potential target for gastric cancer therapy.

  16. Transition metal carbides, nitrides and borides, and their oxygen containing analogs useful as water gas shift catalysts

    DOEpatents

    Thompson, Levi T.; Patt, Jeremy; Moon, Dong Ju; Phillips, Cory

    2003-09-23

    Mono- and bimetallic transition metal carbides, nitrides and borides, and their oxygen containing analogs (e.g. oxycarbides) for use as water gas shift catalysts are described. In a preferred embodiment, the catalysts have the general formula of M1.sub.A M2.sub.B Z.sub.C O.sub.D, wherein M1 is selected from the group consisting of Mo, W, and combinations thereof; M2 is selected from the group consisting of Fe, Ni, Cu, Co, and combinations thereof; Z is selected from the group consisting of carbon, nitrogen, boron, and combinations thereof; A is an integer; B is 0 or an integer greater than 0; C is an integer; O is oxygen; and D is 0 or an integer greater than 0. The catalysts exhibit good reactivity, stability, and sulfur tolerance, as compared to conventional water shift gas catalysts. These catalysts hold promise for use in conjunction with proton exchange membrane fuel cell powered systems.

  17. Pseudogap Phenomena Near the BKT Transition of a Two-Dimensional Ultracold Fermi Gas in the Crossover Region

    NASA Astrophysics Data System (ADS)

    Matsumoto, M.; Hanai, R.; Inotani, D.; Ohashi, Y.

    2017-06-01

    We investigate strong-coupling properties of a two-dimensional ultracold Fermi gas in the normal phase. In the three-dimensional case, it has been shown that the so-called pseudogap phenomena can be well described by a (non-self-consistent) T-matrix approximation (TMA). In the two-dimensional case, while this strong-coupling theory can explain the pseudogap phenomenon in the strong-coupling regime, it unphysically gives large pseudogap size in the crossover region, as well as in the weak-coupling regime. We show that this difficulty can be overcome when one improves TMA to include higher-order pairing fluctuations within the framework of a self-consistent T-matrix approximation (SCTMA). The essence of this improvement is also explained. Since the observation of the BKT transition has recently been reported in a two-dimensional ^6{Li} Fermi gas, our results would be useful for the study of strong-coupling physics associated with this quasi-long-range order.

  18. A nonlinear dynamical 2D coupled mathematical model for phase transitions in methane gas hydrates within permafrost under climate change

    NASA Astrophysics Data System (ADS)

    Duxbury, N. S.; Romanovsky, V. E.; Romanovskii, N. N.; Garagulya, L. S.; Brouchkov, A. V.; Komarov, I. A.; Roman, L. T.; Tipenko, G. S.; Buldovich, S. N.; Maximova, L. N.

    2012-12-01

    We have developed coupled permafrost - carbon physical and numerical models, where carbon is in the form of methane clathrate hydrate ( CH4*6H2O ) in a porous subsurface environment. The driving force for the subsurface temperature field dynamics is climate variations on the Earth's surface. This is an upper boundary condition for the nonlinear evolutionary system of partial differential equations (PDEs) describing subsurface heat transfer (parabolic PDEs) in a generalized Stefan formulation. The developed numerical model is a valuable computational tool to quantitatively study nonlinear dynamical thermal processes with phase transitions in terrestrial and Martian subsurfaces. Our model is multifrontal and therefore allows one to perform computations for a problem with any number of emerging/vanishing phase transition interfaces (both in methane gas hydrate deposits and in permafrost), since the model treats these fronts implicitly in an enthalpy formulation and in corresponding finite-difference scheme. This model takes into account the pressure (and therefore the depth) dependence of the phase transition temperature for methane clathrate hydrate. We have performed model computations using the thermophysical characteristics (heat capacity, density/porosity, thermal conductivity) for the Siberian subsurface. It can be used as a terrestrial analog for the Martian subsurface (e.g., Duxbury et al., 2001). Also, thermophysical coefficients from laboratory experiments for methane clathrate hydrate were used in our model. In addition, our model takes into account the dependence of subsurface thermophysical characteristics on temperature and spatial coordinates. The results of our computations and their interpretation will be presented. References. N. S. Duxbury, I. A. Zotikov, K. H. Nealson, V. E. Romanovsky, F. D. Carsey (2001). A numerical model for an alternative origin of Lake Vostok and its exobiological implications for Mars, Journal of Geophysical Research

  19. MULTI-TRANSITION STUDY OF M51'S MOLECULAR GAS SPIRAL ARMS

    SciTech Connect

    Schinnerer, E.; Weiss, A.; Aalto, S.; Scoville, N. Z.

    2010-08-20

    Two selected regions in the molecular gas spiral arms in M51 were mapped with the Owens Valley Radio Observatory (OVRO) mm-interferometer in the {sup 12}CO(2-1), {sup 13}CO(1-0), C{sup 18}O(1-0), HCN(1-0), and HCO+(1-0) emission lines. The CO data have been combined with the {sup 12}CO(1-0) data from Aalto et al. covering the central 3.5 kpc to study the physical properties of the molecular gas. All CO data cubes were short spacing corrected using IRAM 30 m ({sup 12}CO(1-0): NRO 45 m) single-dish data. A large velocity gradient analysis finds that the giant molecular clouds (GMCs) are similar to Galactic GMCs when studied at 180 pc (120 pc) resolution with an average kinetic temperature of T{sub kin} = 20(16) K and H{sub 2} density of n(H{sub 2}) = 120(240) cm{sup -3} when assuming virialized clouds (a constant velocity gradient dv/dr). The associated conversion factor between H{sub 2} mass and CO luminosity is close to the Galactic value for most regions analyzed. Our findings suggest that the GMC population in the spiral arms of M51 is similar to those of the Milky Way and therefore the strong star formation occurring in the spiral arms has no strong impact on the molecular gas in the spiral arms. Extinction inferred from the derived H{sub 2} column density is very high (A{sub V} about 15-30 mag), about a factor of 5-10 higher than the average value derived toward H II regions. Thus, a significant fraction of the ongoing star formation could be hidden inside the dust lanes of the spiral arms. A comparison of MIPS 24 {mu}m and H{alpha} data, however, suggests that this is not the case and most of the GMCs studied here are not (yet) forming stars. We also present low (4.''5) resolution OVRO maps of the HCN(1-0) and HCO+(1-0) emission at the location of the brightest {sup 12}CO(1-0) peak.

  20. Large Eddy Simulation Of Gravitational Effects In Transitional And Turbulent Gas-Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Jaberi, Farhad A.; Givi, Peyman

    2003-01-01

    The influence of gravity on the spatial and the compositional structures of transitional and turbulent hydrocarbon diffusion flames are studies via large eddy simulation (LES) and direct numerical simulation (DNS) of round and planar jets. The subgrid-scale (SGS) closures in LES are based on the filtered mass density function (FMDF) methodology. The FMDF represents the joint probability density function (PDF) of the SGS scalars, and is obtained by solving its transport equation. The fundamental advantage of LES/FMDF is that it accounts for the effects of chemical reaction and buoyancy exactly. The methodology is employed for capturing some of the fundamental influences of gravity in equilibrium flames via realistic chemical kinetic schemes. Some preliminary investigation of the gravity effects in non-equilibrium flames is also conducted, but with idealized chemical kinetics models.

  1. Large Eddy Simulation of Gravitational Effects on Transitional and Turbulent Gas-Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Givi, Peyman; Jaberi, Farhad A.

    2001-01-01

    The basic objective of this work is to assess the influence of gravity on "the compositional and the spatial structures" of transitional and turbulent diffusion flames via large eddy simulation (LES), and direct numerical simulation (DNS). The DNS is conducted for appraisal of the various closures employed in LES, and to study the effect of buoyancy on the small scale flow features. The LES is based on our "filtered mass density function"' (FMDF) model. The novelty of the methodology is that it allows for reliable simulations with inclusion of "realistic physics." It also allows for detailed analysis of the unsteady large scale flow evolution and compositional flame structure which is not usually possible via Reynolds averaged simulations.

  2. Origins of the deflagration-to-detonation transition in gas-phase combustion

    SciTech Connect

    Oran, Elaine S.; Gamezo, Vadim N.

    2007-01-15

    This paper summarizes a 10-year theoretical and numerical effort to understand the deflagration-to-detonation transition (DDT). To simulate DDT from first principles, it is necessary to resolve the relevant scales ranging from the size of the system to the flame thickness, a range that can cover up to 12 orders of magnitude in real systems. This computational challenge resulted in the development of numerical algorithms for solving coupled partial and ordinary differential equations and a new method for adaptive mesh refinement to deal with multiscale phenomena. Insight into how, when, and where DDT occurs was obtained by analyzing a series of multidimensional numerical simulations of laboratory experiments designed to create a turbulent flame through a series of shock-flame interactions. The simulations showed that these interactions are important for creating the conditions in which DDT can occur. Flames enhance the strength of shocks passing through a turbulent flame brush and generate new shocks. In turn, shock interactions with flames create and drive the turbulence in flames. The turbulent flame itself does not undergo a transition, but it creates conditions in nearby unreacted material that lead to ignition centers, or 'hot spots,' which can then produce a detonation through the Zeldovich gradient mechanism involving gradients of reactivity. Obstacles and boundary layers, through their interactions with shocks and flames, help to create environments in which hot spots can develop. Other scenarios producing reactivity gradients that can lead to detonations include flame-flame interactions, turbulent mixing of hot products with reactant gases, and direct shock ignition. Major unresolved questions concern the properties of nonequilibrium, shock-driven turbulence, stochastic properties of ignition events, and the possibility of unconfined DDT. (author)

  3. Kosterlitz-Thouless Transition of the Quasi-Two-Dimensional Trapped Bose Gas

    SciTech Connect

    Holzmann, Markus; Krauth, Werner

    2008-05-16

    We use quantum Monte Carlo methods to compute the density profile, the nonclassical moment of inertia, and the condensate fraction of an interacting quasi-two-dimensional trapped Bose gas with up to N{approx}5x10{sup 5} atoms and parameters closely related to recent experiments. We locate the Kosterlitz-Thouless temperature T{sub KT} and discuss intrinsic signatures of the onset of superfluidity in the density profile. Below T{sub KT}, the condensate fraction is macroscopic even for our largest systems and decays only slowly with system size. We show that the thermal population of excited states in the transverse direction changes the two-dimensional density profile noticeably in both the normal and the superfluid phase.

  4. Rarefied gas flow in converging microchannel in slip and early transition regimes

    NASA Astrophysics Data System (ADS)

    Hemadri, Vadiraj; Varade, Vijay V.; Agrawal, Amit; Bhandarkar, U. V.

    2017-03-01

    This work presents the study of isothermal rarefied gas flows in converging microchannels. Experiments are carried out on microchannels of three different converging angles (4°, 8°, and 12°). Numerical investigation is carried out using commercial software to study the local behaviour of the flow parameters. The simulations show a sudden drop in the fluid temperature at the exit of the microchannel. Knudsen minimum, which was experimentally observed for the first time recently in diverging microchannels, is also noted here in the case of flow in converging cross section. It is interesting to note that, at the location of Knudsen minimum, the Knudsen number and the value of the minimum mass flow rate are same for both converging and diverging cross sections, for all the angles tested. This result implies the absence of any flow preference at high Knudsen numbers when the flow is subjected to converging and diverging orientations of the microchannel.

  5. Effects of Buoyancy on Laminar, Transitional, and Turbulent Gas Jet Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Bahadori, M. Yousef; Stocker, Dennis P.; Vaughan, David F.; Zhou, Liming; Edelman, Raymond B.

    1993-01-01

    Gas jet diffusion flames have been a subject of research for many years. However, a better understanding of the physical and chemical phenomena occurring in these flames is still needed, and, while the effects of gravity on the burning process have been observed, the basic mechanisms responsible for these changes have yet to be determined. The fundamental mechanisms that control the combustion process are in general coupled and quite complicated. These include mixing, radiation, kinetics, soot formation and disposition, inertia, diffusion, and viscous effects. In order to understand the mechanisms controlling a fire, laboratory-scale laminar and turbulent gas-jet diffusion flames have been extensively studied, which have provided important information in relation to the physico-chemical processes occurring in flames. However, turbulent flames are not fully understood and their understanding requires more fundamental studies of laminar diffusion flames in which the interplay of transport phenomena and chemical kinetics is more tractable. But even this basic, relatively simple flame is not completely characterized in relation to soot formation, radiation, diffusion, and kinetics. Therefore, gaining an understanding of laminar flames is essential to the understanding of turbulent flames, and particularly fires, in which the same basic phenomena occur. In order to improve and verify the theoretical models essential to the interpretation of data, the complexity and degree of coupling of the controlling mechanisms must be reduced. If gravity is isolated, the complication of buoyancy-induced convection would be removed from the problem. In addition, buoyant convection in normal gravity masks the effects of other controlling parameters on the flame. Therefore, the combination of normal-gravity and microgravity data would provide the information, both theoretical and experimental, to improve our understanding of diffusion flames in general, and the effects of gravity on the

  6. Gas hydrate decomposition and migration of the sulfate/methane transition zone recorded by authigenic barite in cold seep sediments

    NASA Astrophysics Data System (ADS)

    Kasten, S.; Hensen, C.; Spiess, V.; Blumenberg, M.; Schneider, R. R.

    2010-12-01

    After deposition of sediments a whole suite of geochemical/biogeochemical and transport processes - subsumed under the term early diagenesis - can potentially alter the primary sediment composition. Post-depositional overprint is not only restricted to the topmost part of the sediment but well extends into more deeply buried sediments. A biogeochemical reaction front which is of particular importance for deep post-depositional alteration is the so-called sulfate/methane transition zone (SMTZ) where the anaerobic oxidation of methane (AOM) by sulfate occurs. This front is often located several meters to several tens of meters within the sediment and can heavily impact a number of sedimentary components and attributes - like carbonates, barite, iron oxide and iron sulfide minerals as well as rock magnetic properties (e.g., magnetic susceptibility). In this way the primary sediment composition is distinctly altered several thousands to tens of thousands of years after deposition. Identifying and quantifying such diagenetic overprint is of the utmost importance to accurately interpret the sedimentary record. In marine environments affected by hydrocarbon seepage and/or the presence of gas hydrates the geochemical zonation is often significantly condensed and the sulfate/methane transition zone is typically located close to the sediment surface - in this way impacting the initial sediment composition at relatively shallow depth. While the process of AOM induces the destruction of several primary sediment components it also goes along with the diagenetic formation of secondary signals. One of these diagenetically formed compounds is authigenic barite which precipitates slightly above the SMTZ. We demonstrate that - following the approach of Dickens (2001) - authigenic barite can be a valuable geochemical proxy to trace the downward migration of the SMTZ over time as a result of the decomposition of gas hydrates and/or a decrease in the upward flux of hydrocarbons

  7. A Gas-Poor Planetesimal Feeding Model for the Formation of Giant Planet Satellite Systems: Consequences for the Atmosphere of Titan

    NASA Technical Reports Server (NTRS)

    Estrada, P. R.; Mosqueira, I.

    2005-01-01

    Given our presently inadequate understanding of the turbulent state of the solar and planetary nebulae, we believe the way to make progress in satellite formation is to consider two end member models that avoid over-reliance on specific choices of the turbulence (alpha), which is essentially a free parameter. The first end member model postulates turbulence decay once giant planet accretion ends. If so, Keplerian disks must eventually pass through the quiescent phases, so that the survival of satellites (and planets) ultimately hinges on gap-opening. In this scenario, the criterion for gap-opening itself sets the value for the gas surface density of the satellite disk.

  8. 3D Architecture of Ultra-Distal Magma-Poor Rifted Margins: the Example of the Fossil Err and Platta Ocean Continent Transition Exposed in the Central Alps in SE Switzerland.

    NASA Astrophysics Data System (ADS)

    Epin, M. E.; Manatschal, G.; Amann, M.; Walter, R.; Lescanne, M.

    2016-12-01

    Despite the fact that many studies have investigated magma-poor rifted margins, there are still numerous questions concerning the 3D architecture of the Ocean-Continent Transitions (OCT) and the tectono- magmatic processes related to lithospheric breakup. Indeed, it has been observed that the top basement morphology of OCT's at magma-poor rifted margins is heavily structured and complex. The aim of this study is to describe the 3D top basement morphology of OCT's and to define the processes and timing of their formation. To do this, we focused on field observations in the Err-Platta nappes (SE Switzerland) which expose over about 300 km² little overprinted remnants of the fossil Jurassic OCT of the Alpine Tethys. First results of the study show spectacularly exposed structures of the OCT, highlighting the important 3D architecture of the hyperextended crustal and exhumed mantle domains. Key structures are a set of fossil detachment systems showing a complex polyphase tectono-magmatic evolution with: 1) strike and dip variations of detachment systems in the hyperextended crust controlled by inherited structures, 2) the 3D architecture of an exhumed mantle core complex, and 3) the sedimentary and magmatic record associated to these structures. The overall observations provide important information on the temporal evolution and spatial organization of the structural and magmatic systems in ultra-distal magma-poor rifted margins. These systems are at the origin of the creation of the ultra-distal parts of rifted margins and are important for the understanding of the processes controlling lithospheric breakup and creation of a new plate boundary. In this context, our field observations can help to better understand the tectono-magmatic processes at not yet drilled ultra-distal magma-poor rifted margins.

  9. Post-Transition State Dynamics in Gas Phase Reactivity: Importance of Bifurcations and Rotational Activation.

    PubMed

    Martín-Sómer, Ana; Yáñez, Manuel; Hase, William L; Gaigeot, Marie-Pierre; Spezia, Riccardo

    2016-03-08

    Beyond the established use of thermodynamic vs kinetic control to explain chemical reaction selectivity, the concept of bifurcations on a potential energy surface (PES) is proving to be of pivotal importance with regard to selectivity. In this article, we studied by means of post-transition state (TS) direct dynamics simulations the effect that vibrational and rotational excitation at the TS may have on selectivity on a bifurcating PES. With this aim, we studied the post-TS unimolecular reactivity of the [Ca(formamide)](2+) ion, for which Coulomb explosion and neutral loss reactions compete. The PES exhibits different kinds of nonintrinsic reaction coordinate (IRC) dynamics, among them PES bifurcations, which direct the trajectories to multiple reaction paths after passing the TS. Direct dynamics simulations were used to distinguish between the bifurcation non-IRC dynamics and non-IRC dynamics arising from atomistic motions directing the trajectories away from the IRC. Overall, we corroborated the idea that kinetic selectivity often does not reduce to a simple choice between paths with different barrier heights and instead dynamical behavior after passing the TS may be crucial. Importantly, rotational excitation may play a pivotal role on the reaction selectivity favoring nonthermodynamic products.

  10. Measurement of the electric conductivity of tungsten in a continuous liquid-to-gas transition

    NASA Astrophysics Data System (ADS)

    Korobenko, V. N.; Rakhel, A. D.; Savvatimskiy, A. I.; Fortov, V. E.

    2002-12-01

    A method is developed that makes it possible to investigate the transition of a metal from a condensed to a gaseous phase while maintaining almost uniform temperature and pressure distributions in the sample. The method consists in the pulsed Joule heating of a sample in the form of a thin foil strip placed between two relatively thick glass plates. This method is used to measure the conductivity of tungsten in a process during which the pressure in the sample is maintained at a level of 40-60 kbar and the density of the sample decreases from the normal solid density to a density 20 to 30 times lower. It is found that, along the 40-kbar isobar, the density dependence of the conductivity of tungsten changes radically at a certain density value, at which it has a pronounced kink. At the kink, the density of tungsten is approximately ten times lower than its characteristic solid density, and the internal energy is about two times the sublimation energy. The method makes it possible to carry out experiments with the almost isobaric heating of tungsten in the parameter range in which the effect in question takes place. No such effect is detected in nonisobaric processes.

  11. A revised host galaxy association for GRB 020819B: a high-redshift dusty starburst, not a low-redshift gas-poor spiral

    NASA Astrophysics Data System (ADS)

    Perley, Daniel A.; Krühler, Thomas; Schady, Patricia; Michałowski, Michał J.; Thöne, Christina C.; Petry, Dirk; Graham, John F.; Greiner, Jochen; Klose, Sylvio; Schulze, Steve; Kim, Sam

    2017-02-01

    The purported spiral host galaxy of GRB 020819B at z = 0.41 has been seminal in establishing our view of the diversity of long-duration gamma-ray burst environments: Optical spectroscopy of this host provided evidence that gamma-ray bursts (GRBs) can form even at high metallicities, whereas millimetric observations suggested that GRBs may preferentially form in regions with minimal molecular gas. We report new observations from the Very Large Telescope (Multi Unit Spectroscopic Explorer and X-shooter), which demonstrate that the purported host is an unrelated foreground galaxy. The probable radio afterglow is coincident with a compact, highly star forming, dusty galaxy at z = 1.9621. The revised redshift naturally explains the apparent non-detection of CO(3-2) line emission at the afterglow site from the Atacama Large Millimetre Observatory. There is no evidence that molecular gas properties in GRB host galaxies are unusual, and limited evidence that GRBs can form readily at a super-Solar metallicity.

  12. Energy and Greenhouse Gas Emissions in China: Growth, Transition, and Institutional Change

    NASA Astrophysics Data System (ADS)

    Kahrl, Fredrich James

    Global energy markets and climate change in the twenty first century depend, to an extraordinary extent, on China. China is now, or will soon be, the world's largest energy consumer. Since 2007, China has been the world's largest emitter of greenhouse gases (GHGs). Despite its large and rapidly expanding influence on global energy markets and the global atmosphere, on a per capita basis energy consumption and GHG emissions in China are low relative to developed countries. The Chinese economy, and with it energy use and GHG emissions, are expected to grow vigorously for at least the next two decades, raising a question of critical historical significance: How can China's economic growth imperative be meaningfully reconciled with its goals of greater energy security and a lower carbon economy? Most scholars, governments, and practitioners have looked to technology---energy efficiency, nuclear power, carbon capture and storage---for answers to this question. Alternatively, this study seeks to root China's future energy and emissions trajectory in the political economy of its multiple transitions, from a centrally planned to a market economy and from an agrarian to a post-industrial society. The study draws on five case studies, each a dedicated chapter, which are organized around three perspectives on energy and GHG emissions: the macroeconomy; electricity supply and demand; and nitrogen fertilizer production and use. Chapters 2 and 3 examine how growth and structural change in China's macroeconomy have shaped energy demand, finding that most of the dramatic growth in the country's energy use over the 2000s was driven by an acceleration of its investment-dominated, energy-intensive growth model, rather than from structural change. Chapters 4 and 5 examine efforts to improve energy efficiency and increase the share of renewable generation in the electric power sector, concluding that China's power system lacks the flexibility in generation, pricing, and demand to

  13. The effusive-explosive transitions at Rokatenda 2012-2013: unloading by extrusion of degassed magma with lateral gas flow

    NASA Astrophysics Data System (ADS)

    Primulyana, Sofyan; Bani, Philipson; Harris, Andrew

    2017-02-01

    Between October 2012 and August 2013, Rokatenda, one of the most poorly understood volcanoes in Indonesia, entered a phase of intense eruptive activity which involved extrusion of viscous lava, gas discharge and explosive activity. During the 10-month-long eruption, a lava volume of 2-5 × 106 m3 was extruded at mean output rate of 0.3 m3 s-1, with 2 to 3-month-long high extrusion rate phases being terminated by explosive events. Extrusion built a lava dome attaining a maximum height of ˜80 m above the crater rim, with a basal width of about 250 m. The composition of the 2012-2013 lava dome is comparable to that of the 1980 lava dome, both being andesite-trachydacite. Mineralogically, the 2012-2013 lava dome is mainly composed of plagioclase, pyroxene and an undetermined opaque mineral. Halogens released during eruption are consistent with the extrusion being fed, at least in the first eruption phase, by a degassed magma. This resulted in the formation of a dense, viscous plug in the conduit that led to a lateral gas flow, with gasses escaping around the plug to form multiple craters surrounding the dome. During the course of the eruptive activity, degassed magma was progressively forced out of the vent to unload deeper magma and force the system into an explosive phase. Such a scenario has occurred in the past at Rokatenda and is likely to be repeated in the future and creates an activity pattern that may be used to characterize such systems.

  14. Accidental exposure to gas emissions from transit goods treated for pest control.

    PubMed

    Kloth, Stefan; Baur, Xaver; Göen, Thomas; Budnik, Lygia Therese

    2014-12-13

    International phytosanitary standards ISPM 15 require (since 2007) fumigation or heat treatment for shipping and storage. Those dealing with fumigated freight might be accidentally exposed. In this paper we report a series of three accidents of six storage room workers in a medium sized company regularly importing electronic production parts from abroad. Patients (n=6, aged from 32-54 yrs.) and control group (n=30, mean 40 yrs.) donated blood and urine samples. The fumigants: ethylene oxide, methyl bromide, chloropicrin, ethylene dichloride, other halo-alkanes and solvents were analyzed by headspace gas chromatography/mass spectrometry (GCMS). For the quantitation of long term exposure/s, macromolecular reaction products (hemoglobin adducts) were used (with GCMS) as molecular dosimeter; additionally 8-OHdG and circulating mtDNA (cmtDNA) were analyzed as nonspecific biological effect markers. The hemoglobin adducts N-methyl valine (MEV) and N-(2-hydroxy ethyl) valine (HEV) were elevated after exposure to the alkylating chemicals methyl bromide and ethylene oxide. Under the consideration of known elimination kinetics and the individual smoking status (biomonitored with nicotine metabolite cotinine and tobacco specific hemoglobin adduct: N-(2 cyan ethyl) valines, CEV), the data allow theoretical extrapolation to the initial protein adduct concentrations at the time of the accident (the MEV/CEV levels were from 1,616 pmol/g globin to 1,880 pmol/g globin and HEV/CEV levels from 1,407 pmol/g globin to 5,049 pmol/g globin, and correlated with inhaled 0.4-1.5 ppm ethylene oxide. These integrated, extrapolated internal doses, calculated on the basis of biological exposure equivalents, confirmed the clinical diagnosis for three patients, showing severe intoxication symptoms. Both, cmtDNA and 8-OHdG, as non-specific biomarkers of toxic effects, were elevated in four patients. The cases reported here, stress the importance of a suitable risk assessment and control measures. We

  15. Vibrational structure of n-π* transition of the UV absorption spectrum of acryloyl fluoride in the gas phase.

    PubMed

    Koroleva, Lidiya A; Tyulin, Vladimir I; Matveev, Vladimir K; Pentin, Yuriy A

    2014-03-25

    UV absorption spectrum of acryloyl fluoride molecule in the gas phase has been obtained in the region at 32600-35500 cm(-1) with the purpose of the investigation of the hindered internal rotation. The resolved vibrational structure of this spectrum consists of 92 absorption bands, each of which corresponds to a certain transition from the ground (S0) to excited (S1) electronic state. The assignment of all bands has been made. The values ν00trans=34831.8 cm(-1) and ν00cis=34679.2 cm(-1) have been determined. Several Deslandres Tables (DTs) have been constructed for torsional vibration of s-trans- and s-cis-isomers of investigated molecule. The origins in these DTs correspond to bands assigned to ν00 and to fundamental frequencies of each isomer in the S0 and S1 states. These DTs have been used to determine the harmonic frequencies ωe, anharmonicity coefficients x11, and frequencies of the torsional vibration transitions (0-υ) up to high values of the vibrational quantum number υ of s-trans- and s-cis-isomers in the both electronic states. The frequencies of torsional vibrations are ν1(″)=116.5cm(-1) for s-trans-isomer and ν1(″)=101.2 cm(-1) for s-cis-isomer in the S0 state. The frequencies of ones are ν1(')=170.4 cm(-1) for s-trans-isomer and ν1(')=139.7 cm(-1) for s-cis-isomer in the S1 state. The fundamental vibrational frequencies set has been found for isomers in the S0 and S1 states.

  16. Critical point of gas-liquid type phase transition and phase equilibrium functions in developed two-component plasma model

    SciTech Connect

    Butlitsky, M. A.; Zelener, B. V.

    2014-07-14

    A two-component plasma model, which we called a “shelf Coulomb” model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The “shelf Coulomb” model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ε parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ε and γ = βe{sup 2}n{sup 1/3} (where β = 1/k{sub B}T, n is the particle's density, k{sub B} is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ε and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of ε{sub crit}≈13(T{sub crit}{sup *}≈0.076),γ{sub crit}≈1.8(v{sub crit}{sup *}≈0.17),P{sub crit}{sup *}≈0.39, where specific volume v* = 1/γ{sup 3} and reduced temperature T{sup *} = ε{sup −1}.

  17. The Transition from Diffuse to Dense Gas in Herschel Dust Emission Maps

    NASA Astrophysics Data System (ADS)

    Goldsmith, Paul

    Dense cores in dark clouds are the sites where young stars form. These regions manifest as relatively small (<0.1pc) pockets of cold and dense gas. If we wish to understand the star formation process, we have to understand the physical conditions in dense cores. This has been a main aim of star formation research in the past decade. Today, we do indeed possess a good knowledge of the density and velocity structure of cores, as well as their chemical evolution and physical lifetime. However, we do not understand well how dense cores form out of the diffuse gas clouds surrounding them. It is crucial that we constrain the relationship between dense cores and their environment: if we only understand dense cores, we may be able to understand how individual stars form --- but we would not know how the star forming dense cores themselves come into existence. We therefore propose to obtain data sets that reveal both dense cores and the clouds containing them in the same map. Based on these maps, we will study how dense cores form out of their natal clouds. Since cores form stars, this knowledge is crucial for the development of a complete theoretical and observational understanding of the formation of stars and their planets, as envisioned in NASA's Strategic Science Plan. Fortunately, existing archival data allow to derive exactly the sort of maps we need for our analysis. Here, we describe a program that exclusively builds on PACS and SPIRE dust emission imaging data from the NASA-supported Herschel mission. The degree-sized wide-field Herschel maps of the nearby (<260pc) Polaris Flare and Aquila Rift clouds are ideal for our work. They permit to resolve dense cores (<0.1pc), while the maps also reveal large-scale cloud structure (5pc and larger). We will generate column density maps from these dust emission maps and then run a tree-based hierarchical multi-scale structure analysis on them. Only this procedure permits to exploit the full potential of the maps: we will

  18. Improved Laboratory Transition Probabilities for Ce II, Application to the Cerium Abundances of the Sun and Five r-Process-Rich, Metal-Poor Stars, and Rare Earth Lab Data Summary

    NASA Astrophysics Data System (ADS)

    Lawler, J. E.; Sneden, C.; Cowan, J. J.; Ivans, I. I.; Den Hartog, E. A.

    2009-05-01

    Recent radiative lifetime measurements accurate to ±5% using laser-induced fluorescence (LIF) on 43 even-parity and 15 odd-parity levels of Ce II have been combined with new branching fractions measured using a Fourier transform spectrometer (FTS) to determine transition probabilities for 921 lines of Ce II. This improved laboratory data set has been used to determine a new solar photospheric Ce abundance, log ɛ = 1.61 ± 0.01 (σ = 0.06 from 45 lines), a value in excellent agreement with the recommended meteoritic abundance, log ɛ = 1.61 ± 0.02. Revised Ce abundances have also been derived for the r-process-rich metal-poor giant stars BD+17°3248, CS 22892-052, CS 31082-001, HD 115444, and HD 221170. Between 26 and 40 lines were used for determining the Ce abundance in these five stars, yielding a small statistical uncertainty of ±0.01 dex similar to the solar result. The relative abundances in the metal-poor stars of Ce and Eu, a nearly pure r-process element in the Sun, matches r-process-only model predictions for solar system material. This consistent match with small scatter over a wide range of stellar metallicities lends support to these predictions of elemental fractions. A companion paper includes an interpretation of these new precision abundance results for Ce as well as new abundance results and interpretation for Pr, Dy, and Tm.

  19. High-temperature superfluidity of the two-component Bose gas in a transition metal dichalcogenide bilayer

    NASA Astrophysics Data System (ADS)

    Berman, Oleg L.; Kezerashvili, Roman Ya.

    2016-06-01

    The high-temperature superfluidity of two-dimensional dipolar excitons in two parallel transition metal dichalcogenide (TMDC) layers is predicted. We study Bose-Einstein condensation in the two-component system of dipolar A and B excitons. The effective mass, energy spectrum of the collective excitations, the sound velocity, and critical temperature are obtained for different TMDC materials. It is shown that in the Bogoliubov approximation, the sound velocity in the two-component dilute exciton Bose gas is always larger than in any one-component exciton system. The difference between the sound velocities for two-component and one-component dilute gases is caused by the fact that the sound velocity for a two-component system depends on the reduced mass of A and B excitons, which is always smaller than the individual mass of A or B exciton. Due to this fact, the critical temperature Tc for superfluidity for the two-component exciton system in a TMDC bilayer is about one order of magnitude higher than Tc in any one-component exciton system. We propose to observe the superfluidity of two-dimensional dipolar excitons in two parallel TMDC layers, which causes two opposite superconducting currents in each TMDC layer.

  20. Condensation of N bosons. II. Nonequilibrium analysis of an ideal Bose gas and the laser phase-transition analogy

    NASA Astrophysics Data System (ADS)

    Kocharovsky, V. V.; Scully, Marlan O.; Zhu, Shi-Yao; Suhail Zubairy, M.

    2000-02-01

    A nonequilibrium approach to the dynamics and statistics of the condensate of an ideal N-atom Bose gas cooling via interaction with a thermal reservoir using the canonical ensemble is developed. We derive simple analytical expressions for the canonical partition function and equilibrium distribution of the number of atoms in the ground state of a trap under different approximations, and compare them with exact numerical results. The N-particle constraint associated with the canonical ensemble is usually a burden. In the words of Kittel, ``in the investigation of the Bose-Einstein...laws it is very inconvenient to impose the restriction that the number of particles in the subsystem shall be held constant.'' But in the present approach, based on the analogy between a second-order phase transition and laser threshold behavior, the N-particle constraint makes the problem easier. We emphasize that the present work provides another example of a case in which equilibrium (detailed balance) solutions to nonequilibrium equations of motion provide a useful supplementary approach to conventional statistical mechanics. We also discuss some dynamical and mesoscopic aspects of Bose-Einstein condensation. The conclusion is that the present analytical (but approximate) results, based on a nonequilibrium approach, are in excellent agreement with exact (but numerical) results. The present analysis has much in common with the quantum theory of the laser.

  1. Infrared Spectroscopy of Cationized Arginine in the Gas Phase: Direct Evidence for the Transition from Nonzwitterionic to Zwitterionic Structure

    PubMed Central

    Bush, Matthew F.; O'Brien, Jeremy T.; Prell, James S.; Saykally, Richard J.; Williams, Evan R.

    2009-01-01

    The gas-phase structures of protonated and alkali metal cationized arginine (Arg) and arginine methyl ester (ArgOMe) are investigated with infrared spectroscopy and ab initio calculations. Infrared spectra, measured in the hydrogen-stretch region, provide compelling evidence that arginine changes from its nonzwitterionic to zwitterionic form with increasing metal ion size, with the transition in structure occurring between lithium and sodium. For sodiated arginine, evidence for both forms is obtained from spectral deconvolution, although the zwitterionic form is predominant. Comparisons of the photodissociation spectra with spectra calculated for low-energy candidate structures provide additional insights into the detailed structures of these ions. Arg•Li+, ArgOMe•Li+, and ArgOMe•Na+ exist in nonzwitterionic forms in which the metal ion is tricoordinated with the amino acid, whereas Arg•Na+ and Arg•K+ predominately exist in a zwitterionic form where the protonated side chain donates one hydrogen bond to the N terminus of the amino acid and the metal ion is bicoordinated with the carboxylate group. Arg•H+ and ArgOMe•H+ have protonated side chains that form the same interaction with the N terminus as zwitterionic, alkali metal cationized arginine, yet both are unambiguously determined to be nonzwitterionic. Calculations indicate that for clusters with protonated side chains, structures with two strong hydrogen bonds are lowest in energy, in disagreement with these experimental results. This study provides new detailed structural assignments and interpretations of previously observed fragmentation patterns for these ions. PMID:17249666

  2. Prediction of slug-to-annular flow pattern transition (STA) for reducing the risk of gas-lift instabilities and effective gas/liquid transport from low-pressure reservoirs

    SciTech Connect

    Toma, P.R.; Vargas, E.; Kuru, E.

    2007-08-15

    Flow-pattern instabilities have frequently been observed in both conventional gas-lifting and unloading operations of water and oil in low-pressure gas and coalbed reservoirs. This paper identifies the slug-to-annular flow-pattern transition (STA) during upward gas/liquid transportation as a potential cause of flow instability in these operations. It is recommended that the slug-flow pattern be used mainly to minimize the pressure drop and gas compression work associated with gas-lifting large volumes of oil and water. Conversely, the annular flow pattern should be used during the unloading operation to produce gas with relatively small amounts of water and condensate. New and efficient artificial lifting strategies are required to transport the liquid out of the depleted gas or coalbed reservoir level to the surface. This paper presents held data and laboratory measurements supporting the hypothesis that STA significantly contributes to flow instabilities and should therefore be avoided in upward gas/liquid transportation operations. Laboratory high-speed measurements of flow-pressure components under a broad range of gas-injection rates including STA have also been included to illustrate the onset of large STA-related flow-pressure oscillations. The latter body of data provides important insights into gas deliquification mechanisms and identifies potential solutions for improved gas-lifting and unloading procedures. A comparison of laboratory data with existing STA models was performed first. Selected models were then numerically tested in field situations. Effective field strategies for avoiding STA occurrence in marginal and new (offshore) field applications (i.e.. through the use of a slug or annular flow pattern regimen from the bottomhole to wellhead levels) are discussed.

  3. Properties of the most metal-poor gas-rich LSB dwarf galaxies SDSS J0015+0104 and J2354-0005 residing in the Eridanus void

    NASA Astrophysics Data System (ADS)

    Pustilnik, S. A.; Martin, J.-M.; Lyamina, Y. A.; Kniazev, A. Y.

    2013-07-01

    SDSS J0015+0104 is the lowest metallicity low surface brightness dwarf (LSBD) galaxy known. The oxygen abundance in its H II region SDSS J001520.70+010436.9 (at ˜1.5 kpc from the galaxy centre) is 12+log (O/H) = 7.07 (Guseva et al.). This galaxy, at the distance of 28.4 Mpc, appears to reside deeply in the volume devoid of luminous massive galaxies, known as the Eridanus void. SDSS J235437.29-000501.6 is another Eridanus void LSBD galaxy, with parameter 12+log (O/H) = 7.36 (also Guseva et al.). We present the results of their H I observations with the Nançay Radio Telescope revealing their high ratios of M(H I)/LB ˜ 2.3. Based on the Sloan Digital Sky Survey images, we derived for both galaxies their radial surface brightness profiles and the main photometric parameters. Their colours and total magnitudes are used to estimate the galaxy stellar mass and ages. The related gas mass fractions, fg ˜ 0.98 and ˜0.97, and the extremely low metallicities (much lower than for their more typical counterparts with the same luminosity) indicate their unevolved status. We compare these Eridanus void LSBDs with several extreme LSBD galaxies residing in the nearby Lynx-Cancer void. Based on the combination of all their unusual properties, the two discussed LSBD galaxies are similar to the unusual LSBDs residing in the closer void. This finding presents additional evidence for the existence in voids of a sizeable fraction of low-mass unevolved galaxies. Their dedicated search might result in the substantial increase of the number of such objects in the local Universe and in the advancement of understanding their nature.

  4. Determination of scale-invariant equations of state without fitting parameters: application to the two-dimensional Bose gas across the Berezinskii-Kosterlitz-Thouless transition.

    PubMed

    Desbuquois, Rémi; Yefsah, Tarik; Chomaz, Lauriane; Weitenberg, Christof; Corman, Laura; Nascimbène, Sylvain; Dalibard, Jean

    2014-07-11

    We present a general "fit-free" method for measuring the equation of state (EoS) of a scale-invariant gas. This method, which is inspired from the procedure introduced by Ku et al. [Science 335, 563 (2012)] for the unitary three-dimensional Fermi gas, provides a general formalism which can be readily applied to any quantum gas in a known trapping potential, in the frame of the local density approximation. We implement this method on a weakly interacting two-dimensional Bose gas across the Berezinskii-Kosterlitz-Thouless transition and determine its EoS with unprecedented accuracy in the critical region. Our measurements provide an important experimental benchmark for classical-field approaches which are believed to accurately describe quantum systems in the weakly interacting but nonperturbative regime.

  5. Geological Transition

    NASA Image and Video Library

    2014-09-11

    This image, taken by NASA Mars Reconnaissance Orbiter, shows the transition between the Murray Formation, in which layers are poorly expressed and difficult to trace from orbit, and the hematite ridge, which is made up of continuous layers.

  6. THE HIGHLY DYNAMIC BEHAVIOR OF THE INNERMOST DUST AND GAS IN THE TRANSITION DISK VARIABLE LRLL 31

    SciTech Connect

    Flaherty, K. M.; Rieke, G.; Muzerolle, J.; Gutermuth, R.; Balog, Z.; Herbst, W.; Megeath, S. T.; Kun, M.

    2011-05-10

    We describe extensive synoptic multi-wavelength observations of the transition disk LRLL 31 in the young cluster IC 348. We combined 4 epochs of IRS spectra, 9 epochs of MIPS photometry, 7 epochs of cold-mission IRAC photometry, and 36 epochs of warm-mission IRAC photometry along with multi-epoch near-infrared spectra, optical spectra, and polarimetry to explore the nature of the rapid variability of this object. We find that the inner disk, as traced by the 2-5 {mu}m excess, stays at the dust sublimation radius while the strength of the excess changes by a factor of eight on weekly timescales, and the 3.6 and 4.5 {mu}m photometry show a drop of 0.35 mag in 1 week followed by a slow 0.5 mag increase over the next 3 weeks. The accretion rate, as measured by Pa{beta} and Br{gamma} emission lines, varies by a factor of five with evidence for a correlation between the accretion rate and the infrared excess. While the gas and dust in the inner disk are fluctuating, the central star stays relatively static. Our observations allow us to put constraints on the physical mechanism responsible for the variability. The variable accretion, and wind, are unlikely to be causes of the variability, but are both effects of the same physical process that disturbs the disk. The lack of periodicity in our infrared monitoring indicates that it is unlikely that there is a companion within {approx}0.4 AU that is perturbing the disk. The most likely explanation is either a companion beyond {approx}0.4 AU or a dynamic interface between the stellar magnetic field and the disk leading to a variable scale height and/or warping of the inner disk.

  7. Criticality of the phase transition on stage two in a lattice-gas model of a graphite anode in a lithium-ion battery.

    PubMed

    Gavilán Arriazu, E M; López de Mishima, B A; Oviedo, O A; Leiva, E P M; Pinto, O A

    2017-08-30

    Herein, a Monte Carlo study within the canonical assembly has been applied to elucidate the lithium-ion phase transition order of a stage II lithium-graphite intercalation compound (LiC12) around the critical point. The results reveal a weakly first-order phase transition at 354.6 ± 0.5 K via measurements that follows the power laws with effective exponents. The graphite-lithium system was emulated within a lattice-gas model, comprising specific insertion sites arranged in four parallel planes with a triangular geometry. Moreover, two different types of energetic interactions were used: a Lennard-Jones potential, for particle interactions in the same plane, and a power law potential that decreased with distance, for particles in different planes. The energy per site and order parameter distribution were used to classify the order of the transition. Furthermore, the order parameters, susceptibility, and heat capacity were computed and analyzed.

  8. A computer program for two-dimensional and axisymmetric nonreacting perfect gas and equilibrium chemically reacting laminar, transitional and-or turbulent boundary layer flows

    NASA Technical Reports Server (NTRS)

    Miner, E. W.; Anderson, E. C.; Lewis, C. H.

    1971-01-01

    A computer program is described in detail for laminar, transitional, and/or turbulent boundary-layer flows of non-reacting (perfect gas) and reacting gas mixtures in chemical equilibrium. An implicit finite difference scheme was developed for both two dimensional and axisymmetric flows over bodies, and in rocket nozzles and hypervelocity wind tunnel nozzles. The program, program subroutines, variables, and input and output data are described. Also included is the output from a sample calculation of fully developed turbulent, perfect gas flow over a flat plate. Input data coding forms and a FORTRAN source listing of the program are included. A method is discussed for obtaining thermodynamic and transport property data which are required to perform boundary-layer calculations for reacting gases in chemical equilibrium.

  9. Kinetic appearance of first-order gas-liquid expanded and liquid expanded-liquid condensed phase transitions below the triple point.

    PubMed

    Hossain, Md Mufazzal; Suzuki, Toshiyuki; Iimura, Ken-ichi; Kato, Teiji

    2006-01-31

    Phase diagram of Gibbs monolayers of mixtures containing n-hexadecyl phosphate (n-HDP) and L-arginine (L-arg) at a molar ratio of 1:2 has been constructed by measuring surface-pressure-time (pi-t) isotherms with film balance and by observing monolayer morphology with Brewster angle microscopy (BAM). This phase diagram shows a triple point for gas (G), liquid expanded (LE), and liquid condensed (LC) phases at around 6.7 degrees C. Above this triple point, a first-order G-LE phase transition occurring at 0 surface pressure is followed by another first-order LE-LC phase transition taking place at a certain higher surface pressure that depends upon temperature. The BAM observation supports these results. Below the triple point, the pi-t measurements show only one first-order phase transition that should be G-LC. All of these findings are in agreement with the general phase diagram of the spread monolayers. However, the BAM observation at a temperature below the triple point shows that the thermodynamically allowed G-LC phase transition is, in fact, a combination of the G-LE and LE-LC phase transitions. The latter two-phase transitions are separated by time and not by the surface pressure, indicating that the G-LC phase transition is kinetically separated into these two-phase transitions. The position of the LE phase below the triple point in the phase diagram is along the phase boundary between the G and LC phases.

  10. Poor Americans: How the Poor White Live.

    ERIC Educational Resources Information Center

    Pilisuk, Marc; Pilisuk, Phyllis

    Contents of this book include the following essays which originally appeared in "Transaction" magazine: (1) "Poor Americans: an introduction," Marc Pilisuk and Phyllis Pilisuk; (2) "How the white poor live," Marc Pilisuk and Phyllis Pilisuk; (3) "The culture of poverty," Oscar Lewis; (4) "Life in Appalachia--the case of Hugh McCaslin," Robert…

  11. Poor Americans: How the Poor White Live.

    ERIC Educational Resources Information Center

    Pilisuk, Marc; Pilisuk, Phyllis

    Contents of this book include the following essays which originally appeared in "Transaction" magazine: (1) "Poor Americans: an introduction," Marc Pilisuk and Phyllis Pilisuk; (2) "How the white poor live," Marc Pilisuk and Phyllis Pilisuk; (3) "The culture of poverty," Oscar Lewis; (4) "Life in Appalachia--the case of Hugh McCaslin," Robert…

  12. Ultrafine PM emissions from natural gas, oxidation-catalyst diesel, and particle-trap diesel heavy-duty transit buses.

    PubMed

    Holmén, Britt A; Ayala, Alberto

    2002-12-01

    This paper addresses how current technologies effective for reducing PM emissions of heavy-duty engines may affect the physical characteristics of the particles emitted. Three in-use transit bus configurations were compared in terms of submicron particle size distributions using simultaneous SMPS measurements under two dilution conditions, a minidiluter and the legislated constant volume sampler (CVS). The compressed natural gas (CNG)-fueled and diesel particulate filter (DPF)-equipped diesel configurations are two "green" alternatives to conventional diesel engines. The CNG bus in this study did not have an oxidation catalyst whereas the diesel configurations (with and without particulate filter) employed catalysts. The DPF was a continuously regenerating trap (CRT). Particle size distributions were collected between 6 and 237 nm using 2-minute SMPS scans during idle and 55 mph steady-state cruise operation. Average particle size distributions collected during idle operation of the diesel baseline bus operating on ultralow sulfur fuel showed evidence for nanoparticle growth under CVS dilution conditions relative to the minidiluter. The CRT effectively reduced both accumulation and nuclei mode concentrations by factors of 10-100 except under CVS dilution conditions where nuclei mode concentrations were measured during 55 mph steady-state cruise that exceeded baseline diesel concentrations. The CVS data suggest some variability in trap performance. The CNG bus had accumulation mode concentrations 10-100x lower than the diesel baseline but often displayed large nuclei modes, especially under CVS dilution conditions. Partly this may be explained by the lack of an oxidation catalyst on the CNG, but differences between the minidiluter and CVS size distributions suggest that dilution ratio, temperature-related wall interactions, and differences in tunnel background between the diluters contributed to creating nanoparticle concentrations that sometimes exceeded diesel

  13. Two-equation low-Reynolds-number turbulence modeling of transitional boundary layer flows characteristic of gas turbine blades. Ph. D. Thesis. Final Contractor Report

    SciTech Connect

    Schmidt, R.C.; Patankar, S.V.

    1988-05-01

    The use of low Reynolds number (LRN) forms of the k-epsilon turbulence model in predicting transitional boundary layer flow characteristic of gas turbine blades is developed. The research presented consists of: (1) an evaluation of two existing models; (2) the development of a modification to current LRN models; and (3) the extensive testing of the proposed model against experimental data. The prediction characteristics and capabilities of the Jones-Launder (1972) and Lam-Bremhorst (1981) LRN k-epsilon models are evaluated with respect to the prediction of transition on flat plates. Next, the mechanism by which the models simulate transition is considered and the need for additional constraints is discussed. Finally, the transition predictions of a new model are compared with a wide range of different experiments, including transitional flows with free-stream turbulence under conditions of flat plate constant velocity, flat plate constant acceleration, flat plate but strongly variable acceleration, and flow around turbine blade test cascades. In general, calculational procedure yields good agreement with most of the experiments.

  14. Two-Equation Low-Reynolds-Number Turbulence Modeling of Transitional Boundary Layer Flows Characteristic of Gas Turbine Blades. Ph.D. Thesis. Final Contractor Report

    NASA Technical Reports Server (NTRS)

    Schmidt, Rodney C.; Patankar, Suhas V.

    1988-01-01

    The use of low Reynolds number (LRN) forms of the k-epsilon turbulence model in predicting transitional boundary layer flow characteristic of gas turbine blades is developed. The research presented consists of: (1) an evaluation of two existing models; (2) the development of a modification to current LRN models; and (3) the extensive testing of the proposed model against experimental data. The prediction characteristics and capabilities of the Jones-Launder (1972) and Lam-Bremhorst (1981) LRN k-epsilon models are evaluated with respect to the prediction of transition on flat plates. Next, the mechanism by which the models simulate transition is considered and the need for additional constraints is discussed. Finally, the transition predictions of a new model are compared with a wide range of different experiments, including transitional flows with free-stream turbulence under conditions of flat plate constant velocity, flat plate constant acceleration, flat plate but strongly variable acceleration, and flow around turbine blade test cascades. In general, calculational procedure yields good agreement with most of the experiments.

  15. THE TRANSITION OF A SPACE VEHICLE, BRAKED IN THE ATMOSPHERE OF A PLANET, INTO THE ORBIT OF AN ARTIFICIAL SATELLITE AND AXIALLY SYMMETRIC OSCILLATIONS OF CYLINDRICAL SHELLS IN SUPERSONIC FLOW OF GAS,

    DTIC Science & Technology

    Translations of Russian research: Transition of a space vehicle , braked in the atmosphere of a planet, into the orbit of an artificial satellite; axially symmetric oscillations of cylindrical shells in supersonic flow of gas.

  16. Changes in time-use and drug use by young adults in poor neighbourhoods of Greater Buenos Aires, Argentina, after the political transitions of 2001-2002: Results of a survey

    PubMed Central

    2011-01-01

    Background In some countries, "Big Events" like crises and transitions have been followed by large increases in drug use, drug injection and HIV/AIDS. Argentina experienced an economic crisis and political transition in 2001/2002 that affected how people use their time. This paper studies how time use changes between years 2001 and 2004, subsequent to these events, were associated with drug consumption in poor neighbourhoods of Greater Buenos Aires. Methods In 2003-2004, 68 current injecting drug users (IDUs) and 235 young non-IDUs, aged 21-35, who lived in impoverished drug-impacted neighbourhoods in Greater Buenos Aires, were asked about time use then and in 2001. Data on weekly hours spent working or looking for work, doing housework/childcare, consuming drugs, being with friends, and hanging out in the neighbourhood, were studied in relation to time spent using drugs. Field observations and focus groups were also conducted. Results After 2001, among both IDUs and non-IDUs, mean weekly time spent working declined significantly (especially among IDUs); time spent looking for work increased, and time spent with friends and hanging out in the neighbourhood decreased. We found no increase in injecting or non-injecting drug consumption after 2001. Subjects most affected by the way the crises led to decreased work time and/or to increased time looking for work--and by the associated increase in time spent in one's neighbourhood--were most likely to increase their time using drugs. Conclusions Time use methods are useful to study changes in drug use and their relationships to every day life activities. In these previously-drug-impacted neighbourhoods, the Argentinean crisis did not lead to an increase in drug use, which somewhat contradicts our initial expectations. Nevertheless, those for whom the crises led to decreased work time, increased time looking for work, and increased time spent in indoor or outdoor neighbourhood environments, were likely to spend more time

  17. HCO+ Detection of Dust-depleted Gas in the Inner Hole of the LkCa 15 Pre-transitional Disk

    NASA Astrophysics Data System (ADS)

    Drabek-Maunder, E.; Mohanty, S.; Greaves, J.; Kamp, I.; Meijerink, R.; Spaans, M.; Thi, W.-F.; Woitke, P.

    2016-12-01

    LkCa 15 is an extensively studied star in the Taurus region, known for its pre-transitional disk with a large inner cavity in the dust continuum and normal gas accretion rate. The most popular hypothesis to explain the LkCa 15 data invokes one or more planets to carve out the inner cavity, while gas continues to flow across the gap from the outer disk onto the central star. We present spatially unresolved HCO+ J=4\\to 3 observations of the LkCa 15 disk from the James Clerk Maxwell telescope (JCMT) and model the data with the ProDiMo code. We find that: (1) HCO+ line-wings are clearly detected, certifying the presence of gas in the cavity within ≲50 au of the star. (2) Reproducing the observed line-wing flux requires both a significant suppression of cavity dust (by a factor ≳104 compared to the interstellar medium (ISM)) and a substantial increase in the gas scale-height within the cavity (H 0/R 0 ˜ 0.6). An ISM dust-to-gas ratio (d:g = 10-2) yields too little line-wing flux, regardless of the scale-height or cavity gas geometry, while a smaller scale-height also under-predicts the flux even with a reduced d:g. (3) The cavity gas mass is consistent with the surface density profile of the outer disk extended inwards to the sublimation radius (corresponding to mass M d ˜ 0.03 M ⊙), and masses lower by a factor ≳10 appear to be ruled out.

  18. Educational attainment in poor comprehenders

    PubMed Central

    Ricketts, Jessie; Sperring, Rachael; Nation, Kate

    2014-01-01

    To date, only one study has investigated educational attainment in poor (reading) comprehenders, providing evidence of poor performance on national UK school tests at age 11 years relative to peers (Cain and Oakhill, 2006). In the present study, we adopted a longitudinal approach, tracking attainment on such tests from 11 years to the end of compulsory schooling in the UK (age 16 years). We aimed to investigate the proposal that educational weaknesses (defined as poor performance on national assessments) might become more pronounced over time, as the curriculum places increasing demands on reading comprehension. Participants comprised 15 poor comprehenders and 15 controls; groups were matched for chronological age, nonverbal reasoning ability and decoding skill. Children were identified at age 9 years using standardized measures of nonverbal reasoning, decoding and reading comprehension. These measures, along with a measure of oral vocabulary knowledge, were repeated at age 11 years. Data on educational attainment were collected from all participants (n = 30) at age 11 and from a subgroup (n = 21) at 16 years. Compared to controls, educational attainment in poor comprehenders was lower at ages 11 and 16 years, an effect that was significant at 11 years. When poor comprehenders were compared to national performance levels, they showed significantly lower performance at both time points. Low educational attainment was not evident for all poor comprehenders. Nonetheless, our findings point to a link between reading comprehension difficulties in mid to late childhood and poor educational outcomes at ages 11 and 16 years. At these ages, pupils in the UK are making key transitions: they move from primary to secondary schools at 11, and out of compulsory schooling at 16. PMID:24904464

  19. A GAS GIANT CIRCUMBINARY PLANET TRANSITING THE F STAR PRIMARY OF THE ECLIPSING BINARY STAR KIC 4862625 AND THE INDEPENDENT DISCOVERY AND CHARACTERIZATION OF THE TWO TRANSITING PLANETS IN THE KEPLER-47 SYSTEM

    SciTech Connect

    Kostov, V. B.; Tsvetanov, Z. I.; McCullough, P. R.; Valenti, J. A.; Hinse, T. C.; Hebrard, G.; Diaz, R. F.; Deleuil, M.

    2013-06-10

    We report the discovery of a transiting, gas giant circumbinary planet orbiting the eclipsing binary KIC 4862625 and describe our independent discovery of the two transiting planets orbiting Kepler-47. We describe a simple and semi-automated procedure for identifying individual transits in light curves and present our follow-up measurements of the two circumbinary systems. For the KIC 4862625 system, the 0.52 {+-} 0.018 R{sub Jupiter} radius planet revolves every {approx}138 days and occults the 1.47 {+-} 0.08 M{sub Sun }, 1.7 {+-} 0.06 R{sub Sun} F8 IV primary star producing aperiodic transits of variable durations commensurate with the configuration of the eclipsing binary star. Our best-fit model indicates the orbit has a semi-major axis of 0.64 AU and is slightly eccentric, e = 0.1. For the Kepler-47 system, we confirm the results of Orosz et al. Modulations in the radial velocity of KIC 4862625A are measured both spectroscopically and photometrically, i.e., via Doppler boosting, and produce similar results.

  20. Constraining the Structure of the Transition Disk HD 135344B (SAO 206462) by Simultaneous Modeling of Multiwavelength Gas and Dust Observations

    NASA Technical Reports Server (NTRS)

    Carmona, A.; Pinte, C.; Thi, W. F.; Benisty, M.; Menard, F.; Grady, C.; Kamp, I.; Woitke, P.; Olofsson, J.; Roberge, A.; Brittain, S.; Duchene, G.; Meeus, G.; Martin-Zaidi, C.; Dent, B.; Le Bouquin, J. E.; Berger, J. P.

    2014-01-01

    Context: Constraining the gas and dust disk structure of transition disks, particularly in the inner dust cavity, is a crucial step toward understanding the link between them and planet formation. HD 135344B is an accreting (pre-)transition disk that displays the CO 4.7 micrometer emission extending tens of AU inside its 30 AU dust cavity. Aims: We constrain HD 135344B's disk structure from multi-instrument gas and dust observations. Methods: We used the dust radiative transfer code MCFOST and the thermochemical code ProDiMo to derive the disk structure from the simultaneous modeling of the spectral energy distribution (SED), VLT/CRIRES CO P(10) 4.75 Micrometers, Herschel/PACS [O(sub I)] 63 Micrometers, Spitzer/IRS, and JCMT CO-12 J = 3-2 spectra, VLTI/PIONIER H-band visibilities, and constraints from (sub-)mm continuum interferometry and near-IR imaging. Results: We found a disk model able to describe the current gas and dust observations simultaneously. This disk has the following structure. (1) To simultaneously reproduce the SED, the near-IR interferometry data, and the CO ro-vibrational emission, refractory grains (we suggest carbon) are present inside the silicate sublimation radius (0.08 is less than R less than 0.2 AU). (2) The dust cavity (R is less than 30 AU) is filled with gas, the surface density of the gas inside the cavity must increase with radius to fit the CO ro-vibrational line profile, a small gap of a few AU in the gas distribution is compatible with current data, and a large gap of tens of AU in the gas does not appear likely. (4) The gas-to-dust ratio inside the cavity is >100 to account for the 870 Micrometers continuum upper limit and the CO P(10) line flux. (5) The gas-to-dust ratio in the outer disk (30 is less than R less than 200 AU) is less than 10 to simultaneously describe the [O(sub I)] 63 Micrometers line flux and the CO P(10) line profile. (6) In the outer disk, most of the gas and dust mass should be located in the midplane, and

  1. The Elum Project: A Network of UK Sites to Understand Land-Use Transitions to Bioenergy and Their Implications for Greenhouse Gas Balance and Carbon Cycling

    NASA Astrophysics Data System (ADS)

    Harris, Z. M.; Alberti, G.; Bottoms, E.; Rowe, R.; Parmar, K.; Marshall, R.; Elias, D.; Smith, P.; Dondini, M.; Pogson, M.; Richards, M.; Finch, J.; Ineson, P.; Keane, B.; Perks, M.; Wilkinson, M.; Yamulki, S.; Donnison, I.; Farrar, K.; Massey, A.; McCalmont, J.; Drewer, J.; Sohi, S.; McNamara, N.; Taylor, G.

    2014-12-01

    Rising anthropogenic greenhouse gas (GHG) emissions coupled with an increasing need to address energy security are resulting in the development of cleaner, more sustainable alternatives to traditional fossil fuel sources. Bioenergy crops have been proposed to be able to mitigate the effects of climate change as well as provide increased energy security. The aim of this project is to assess the impact of land conversion to second generation non-food bioenergy crops on GHG balance for several land use transitions, including from arable, grassland and forest. A network of 6 sites was established across the UK to assess the processes underpinning GHG balance and to provide input data to a model being used to assess the sustainability of different land use transitions. Monthly analysis of soil GHGs shows that carbon dioxide contributes most to the global warming potential of these bioenergy crops, irrespective of transition. Nitrous oxide emissions were low for all crops except arable cropping and methane emissions were very low for all sites. Nearly all sites have shown a significant decrease in CO2 flux from the control land use. Eddy flux approaches, coupled with soil assessments show that for the transition from grassland to SRC willow there is a significant reduction in GHG emissions from soil and a negative net ecosystem exchange due to increased GPP and ecosystem respiration. These results suggest for this land use transition to bioenergy in a UK specific context, there may be a net benefit for ecosystem GHG exchange of transition to bioenergy Finally we are developing a meta-modelling tool to allow land use managers to make location-specific, informed decisions about land use change to bioenergy. This work is based on the Ecosystem Land Use Modelling & Soil Carbon GHG Flux Trial (ELUM) project, which was commissioned and funded by the Energy Technologies Institute (ETI). This project is co-ordinated by the Centre for Ecology & Hydrology (www.elum.ac.uk).

  2. A Bayesian approach shows no correlation between transit-depth and stellar metallicity for confirmed and candidates Kepler gas giants planets

    NASA Astrophysics Data System (ADS)

    Nehmé, C.; Sarkis, P.

    2017-06-01

    Previous study to investigate the correlation between the transit depth and the stellar metallicity of Kepler’s (Q1-Q12) gas giant planets (radii of 5-20R⊙) has led to a weakly significant negative correlation. We use the cumulative catalog of planets detected by the NASA Kepler mission Q1-Q17 catalog, as of April 2015, to perform a solid statistical analysis of this correlation. In the present work, we revise this correlation, within a Bayesian framework, for two large samples: sample A confirmed planets and sample B (confirmed + candidates). We expand a hierarchical method to account for false positives in the studied samples. Our statistical analysis reveals no correlation between the transit depth and the stellar metallicity. This has implications for planet formation theory and interior structure of giant planets.

  3. Sterilizing the Poor

    ERIC Educational Resources Information Center

    Rothman, Sheila M.

    1977-01-01

    Suggests that freedom for the middle classes may mean vulnerability for the poor. The enthusiasm for sterilization may be so intense as to deprive the poor of their right not to be sterilized. (Author/AM)

  4. Numerical solution of the hypersonic viscous-shock-layer equations for laminar, transitional, and turbulent flows of a perfect gas over blunt axially symmetric bodies

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous shock layer equations applicable to hypersonic laminar, transitional, and turbulent flows of a perfect gas over two-dimensional plane or axially symmetric blunt bodies are presented. The equations are solved by means of an implicit finite difference scheme, and the results are compared with a turbulent boundary layer analysis. The agreement between the two solution procedures is satisfactory for the region of flow where streamline swallowing effects are negligible. For the downstream regions, where streamline swallowing effects are present, the expected differences in the two solution procedures are evident.

  5. Impact of buffer gas quenching on the 1S0 → 1P1 ground-state atomic transition in nobelium

    NASA Astrophysics Data System (ADS)

    Chhetri, Premaditya; Ackermann, Dieter; Backe, Hartmut; Block, Michael; Cheal, Bradley; Düllmann, Christoph Emanuel; Even, Julia; Ferrer, Rafael; Giacoppo, Francesca; Götz, Stefan; Heßberger, Fritz Peter; Kaleja, Oliver; Khuyagbaatar, Jadambaa; Kunz, Peter; Laatiaoui, Mustapha; Lautenschläger, Felix; Lauth, Werner; Ramirez, Enrique Minaya; Mistry, Andrew Kishor; Raeder, Sebastian; Wraith, Calvin; Walther, Thomas; Yakushev, Alexander

    2017-07-01

    Using the sensitive Radiation Detected Resonance Ionization Spectroscopy (RADRIS) technique an optical transition in neutral nobelium (No, Z = 102) was identified. A remnant signal when delaying the ionizing laser indicated the influence of a strong buffer gas induced de-excitation of the optically populated level. A subsequent investigation of the chemical homologue, ytterbium (Yb, Z = 70), enabled a detailed study of the atomic levels involved in this process, leading to the development of a rate equation model. This paves the way for characterizing resonance ionization spectroscopy (RIS) schemes used in the study of nobelium and beyond, where atomic properties are currently unknown.

  6. Discovery of Galactic O iv and O v X-ray absorption due to transition temperature gas in the PKS 2155-304 spectrum

    NASA Astrophysics Data System (ADS)

    Nevalainen, J.; Wakker, B.; Kaastra, J.; Bonamente, M.; Snowden, S.; Paerels, F.; de Vries, C.

    2017-09-01

    Far-ultraviolet (FUV) observations have revealed transition temperature gas (TTG; log T(K) 5), located in the lower Galactic halo and in high-velocity clouds. However, the corresponding X-ray absorption has so far remained mostly undetected. In order to make an improvement in this respect in Galactic X-ray absorption studies, we accumulated very deep ( 3 Ms) spectra of the blazar PKS 2155-304 obtained with the spectrometers RGS1, RGS2, LETG/HRC, and LETG/ACIS-S and studied the absorption lines due to the intervening Galactic components. The very high quality of the data and coverage of important wavelengths with at least two independent instruments allowed us to reliably detect 10 Galactic lines with better than 99.75% confidence. We discovered significant absorption from blended O iv transitions 1s-2p 2S (22.571 Å), 1s-2p 2P (22.741 Å), and 1s-2p 2D (22.777 Å), and from the O v transition 1s-2p (22.370 Å) from TTG at log T(K)=5.2 ± 0.1. A joint X-ray and FUV analysis indicated that photoionisation is negligible for this component and that the gas is in a cooling transition phase. However, the temperature is high enough that the column density ratio N(O iv)/N(O v) is not significantly different from that in collisional ionisation equilibrium (CIE). Under CIE we obtained NOIV = 3.6 ± 2.0 ×1015 cm-2, corresponding to NH = 1.0 ± 0.5 ×1019(Z⊙/ZTTG) cm-2.

  7. Criteria pollutant and greenhouse gas emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies.

    PubMed

    Yoon, Seungju; Collins, John; Thiruvengadam, Arvind; Gautam, Mridul; Herner, Jorn; Ayala, Alberto

    2013-08-01

    Engine and exhaust control technologies applied to compressed natural gas (CNG) transit buses have advanced from lean-burn, to lean-burn with oxidation catalyst (OxC), to stoichiometric combustion with three-way catalyst (TWC). With this technology advancement, regulated gaseous and particulate matter emissions have been significantly reduced. Two CNG transit buses equipped with stoichiometric combustion engines and TWCs were tested on a chassis dynamometer, and their emissions were measured. Emissions from the stoichiometric engines with TWCs were then compared to the emissions from lean-burn CNG transit buses tested in previous studies. Stoichiometric combustion with TWC was effective in reducing emissions of oxides of nitrogen (NO(x)), particulate matter (PM), and nonmethane hydrocarbon (NMHC) by 87% to 98% depending on pollutants and test cycles, compared to lean combustion. The high removal efficiencies exceeded the emission reduction required from the certification standards, especially for NO(x) and PM. While the certification standards require 95% and 90% reductions for NO(x) and PM, respectively, from the engine model years 1998-2003 to the engine model year 2007, the measured NO(x) and PM emissions show 96% and 95% reductions, respectively, from the lean-burn engines to the stoichiometric engines with TWC over the transient Urban Dynamometer Driving Schedule (UDDS) cycle. One drawback of stoichiometric combustion with TWC is that this technology produces higher carbon monoxide (CO) emissions than lean combustion. In regard to controlling CO emissions, lean combustion with OxC is more effective than stoichiometric combustion. Stoichiometric combustion with TWC produced higher greenhouse gas (GHG) emissions including carbon dioxide (CO2) and methane (CH4) than lean combustion during the UDDS cycle, but lower GHG emissions during the steady-state cruise cycle. Stoichiometric combustion with three-way catalyst is currently the best emission control technology

  8. Molecular Gas in Young Debris Disks

    NASA Astrophysics Data System (ADS)

    Moór, Attila; Kóspál, Ágnes; Ábrahám, Péter; Juhász, Attila; Apai, Dániel; Csengeri, Timea; Grady, Carol; Henning, Thomas; Kiss, Csaba; Pascucci, Ilaria

    2013-07-01

    Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. So far only a very few debris disks with measurable gas component have been known. We carried out a survey with the APEX radio telescope to detect molecular gas at millimeter wavelengths in 28 infrared-luminous young debris disks, and discovered two new systems with substantial amount of CO. Motivated to understand the origin, physics, and evolutionary status of the gas in these systems we observed one of them, HD 21997, with ALMA and Herschel. Our results suggest that HD 21997 may be a hybrid system where secondary debris dust and residual primordial gas coexist. This poses a serious question to the current paradigm, since the age of the system (30 Myr) significantly exceeds model predictions for disk clearing and the ages of the oldest transitional disks.

  9. Light Scattering in Exoplanet Transits

    NASA Astrophysics Data System (ADS)

    Robinson, Tyler D.; Fortney, Jonathan J.

    2016-10-01

    Transit spectroscopy is currently the leading technique for studying exoplanet atmospheric composition, and has led to the detection of molecular species, clouds, and/or hazes for numerous worlds outside the Solar System. The field of exoplanet transit spectroscopy will be revolutionized with the anticipated launch of NASA's James Webb Space Telescope (JWST) in 2018. Over the course of the design five year mission for JWST, the observatory is expected to provide in-depth observations of many tens of transiting exoplanets, including some worlds in the poorly understood 2-4 Earth-mass regime. As the quality of transit spectrum observations continues to improve, so should models of exoplanet transits. Thus, certain processes initially thought to be of second-order importance should be revisited and possibly added to modeling tools. For example, atmospheric refraction, which was commonly omitted from early transit spectrum models, has recently been shown to be of critical importance in some terrestrial exoplanet transits. Beyond refraction, another process that has seen little study with regards to exoplanet transits is light multiple scattering. In most cases, scattering opacity in exoplanet transits has been treated as equivalent to absorption opacity. However, this equivalence cannot always hold, such as in the case of a strongly forward scattering, weakly absorbing aerosol. In this presentation, we outline a theory of exoplanet transit spectroscopy that spans the geometric limit (used in most modern models) to a fully multiple scattering approach. We discuss a new technique for improving model efficiency that effectively separates photon paths, which tend to vary slowly in wavelength, from photon absorption, which can vary rapidly in wavelength. Using this newly developed approach, we explore situations where cloud or haze scattering may be important to JWST observations of gas giants, and comment on the conditions necessary for scattering to become a major

  10. Mathematical modeling of gas-condensate mixture filtration in porous media taking into account non-equilibrium of phase transitions

    NASA Astrophysics Data System (ADS)

    Kachalov, V. V.; Molchanov, D. A.; Sokotushchenko, V. N.; Zaichenko, V. M.

    2016-11-01

    At the present time, a considerable part of the largest dry gas reservoirs in Russia are found in the stage of declining production, therefore active exploitation of gas-condensate fields will begin in the coming decades. There is a significant discrepancy between the project and the actual value of condensate recovery factor while producing reservoir of this type, which is caused by insufficient knowledge about non-equilibrium filtration mechanisms of gas-condensate mixtures in reservoir conditions. A system of differential equations to describe filtration process of two-phase multicomponent mixture for one-, two- and three-dimensional cases is presented in this work. The solution of the described system was made by finite-element method in the software package FlexPDE. Comparative distributions of velocities, pressures, saturations and phase compositions of three-component mixture along the reservoir model and in time in both cases of equilibrium and non-equilibrium filtration processes were obtained. Calculation results have shown that system deviation from the thermodynamic equilibrium increases gas phase flow rate and reduces liquid phase flow rate during filtration process of gas-condensate mixture.

  11. Two-photon microwave transitions and strong-field effects in a room-temperature Rydberg-atom gas

    NASA Astrophysics Data System (ADS)

    Anderson, D. A.; Schwarzkopf, A.; Miller, S. A.; Thaicharoen, N.; Raithel, G.; Gordon, J. A.; Holloway, C. L.

    2014-10-01

    We investigate two-photon Autler-Townes splitting and strong-field effects of 85Rb Rydberg atoms in a room-temperature vapor cell. To observe the level structure we employ electromagnetically induced transparency. We first study the two-photon 62 S1 /2-63 S1 /2 microwave transition using an electric-field reference measurement obtained with the one-photon 62 S1 /2-62 P3 /2 transition. We then study the 61 D5 /2-62 D5 /2 transition where the microwave electric-field range is extended up to ˜40 V /m . A Floquet analysis is used to model field-induced level shifts and state-mixing effects present in the strongly driven quantum systems under consideration. Calculations are found to be in good agreement with experimental observations.

  12. Transition from parabolic to ring-shaped valence band maximum in few-layer GaS, GaSe, and InSe

    NASA Astrophysics Data System (ADS)

    Rybkovskiy, Dmitry V.; Osadchy, Alexander V.; Obraztsova, Elena D.

    2014-12-01

    By performing first-principles electronic structure calculations in frames of density functional theory we study the dependence of the valence band shape on the thickness of few-layer III-VI crystals (GaS, GaSe, and InSe). We estimate the critical thickness of transition from the bulklike parabolic to the ring-shaped valence band. Direct supercell calculations show that the ring-shaped extremum of the valence band appears in β -GaS and β -GaSe at a thickness below 6 tetralayers (˜4.6 nm ) and 8 tetralayers (˜6.4 nm ), respectively. Zone-folding calculations estimate the β -InSe critical thickness to be equal to 28 tetralayers (˜24.0 nm ). The origin of the ring-shaped valence band maximum can be understood in terms of k.p theory, which provides a link between the curvature of the energy bands and the distance between them. We explain the dependence of the band shape on the thickness, as well as the transition between two types of extremes, by the k -dependent orbital composition of the topmost valence band. We show that in the vicinity of critical thickness the effective mass of holes in III-VI compounds depends strongly on the number of tetralayers.

  13. Superfluid to Normal Fluid Phase Transition in the Bose Gas Trapped in Two-Dimensional Optical Lattices at Finite Temperature

    NASA Astrophysics Data System (ADS)

    Pires, M. O. C.; de Passos, E. J. V.

    2017-02-01

    We develop the Hartree-Fock-Bogoliubov theory at finite temperature for Bose gas trapped in the two-dimensional optical lattice with the on-site energy low enough that the gas presents superfluid properties. We obtain the condensate density as function of the temperature neglecting the anomalous density in the thermodynamics equation. The condensate fraction provides two critical temperature. Below the temperature T_{C1}, there is one condensate fraction. Above two condensate fractions merger up to the critical temperature T_{C2}. At temperatures larger than T_{C2}, the condensate fraction is null and, therefore, the gas is normal fluid. We resume by a finite-temperature phase diagram where three domains can be identified: the normal fluid, the superfluid with one stable condensate fraction and the superfluid with two condensate fractions being unstable one of them.

  14. Specific Heat of Ultracold Fermi Gas with a Uniaxially Anisotropic p-Wave Interaction at the Superfluid Transition Temperature

    NASA Astrophysics Data System (ADS)

    Inotani, D.; van Wyk, P.; Ohashi, Y.

    2017-06-01

    We theoretically investigate the specific heat at constant volume C_V and strong-coupling effects in a Fermi gas with p-wave interaction. In a ^{40}K Fermi gas, a uniaxial anisotropy of a p-wave interaction associated with a p-wave Feshbach resonance is expected as a result of the split of the p-wave Feshbach resonance by a dipole interaction. Including this, as well as pairing fluctuations, we show that C_V is significantly affected by this anisotropy in the strong-coupling regime. We also discuss the physical origin of this effect. Our results would contribute to the further understanding of an ultracold p-wave Fermi gas.

  15. Urban University Access and Affordability: The Implications of the Relationship between Gas Prices and Suburban Transit Ridership

    ERIC Educational Resources Information Center

    Baginski, Jessie

    2010-01-01

    Many college campuses across the country have implemented U-Pass transit programs to mitigate transportation costs for students. However, urban university U-pass programs fall short for suburban students who cannot get to the urban metro area without connecting public transportation. As urban universities rely on suburbs as feeder communities,…

  16. Urban University Access and Affordability: The Implications of the Relationship between Gas Prices and Suburban Transit Ridership

    ERIC Educational Resources Information Center

    Baginski, Jessie

    2010-01-01

    Many college campuses across the country have implemented U-Pass transit programs to mitigate transportation costs for students. However, urban university U-pass programs fall short for suburban students who cannot get to the urban metro area without connecting public transportation. As urban universities rely on suburbs as feeder communities,…

  17. In-vehicle measurement of ultrafine particles on compressed natural gas, conventional diesel, and oxidation-catalyst diesel heavy-duty transit buses.

    PubMed

    Hammond, Davyda; Jones, Steven; Lalor, Melinda

    2007-02-01

    Many metropolitan transit authorities are considering upgrading transit bus fleets to decrease ambient criteria pollutant levels. Advancements in engine and fuel technology have lead to a generation of lower-emission buses in a variety of fuel types. Dynamometer tests show substantial reductions in particulate mass emissions for younger buses (<10 years) over older models, but particle number reduction has not been verified in the research. Recent studies suggest that particle number is a more important factor than particle mass in determining health effects. In-vehicle particle number concentration measurements on conventional diesel, oxidation-catalyst diesel and compressed natural gas transit buses are compared to estimate relative in-vehicle particulate exposures. Two primary consistencies are observed from the data: the CNG buses have average particle count concentrations near the average concentrations for the oxidation-catalyst diesel buses, and the conventional diesel buses have average particle count concentrations approximately three to four times greater than the CNG buses. Particle number concentrations are also noticeably affected by bus idling behavior and ventilation options, such as, window position and air conditioning.

  18. Hydrogen peroxide in the marine atmospheric boundary layer during the Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange experiment in the eastern subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Martin, Daniel; Tsivou, Maria; Bonsang, Bernard; Abonnel, Christian; Carsey, Thomas; Springer-Young, Margie; Pszenny, Alex; Suhre, Karsten

    1997-03-01

    Gas phase H2O2 was measured in surface air on the NOAA ship Malcolm Baldrige from June 8 to 27, 1992 (Julian days 160-179), during the Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange experiment in the eastern subtropical North Atlantic region. Average H2O2 mixing ratios observed were 0.63±0.28 ppbv, ranging between detection limit and 1.5 ppbv. For the entire experiment, only weak or no correlation was found between H2O2 mixing ratio and meteorological parameters (pressure, temperature, humidity, or UV radiation flux) as well as with tracers of continental air masses (CO, black carbon, radon). The average daily H2O2 cycle for the entire period exhibits a maximum of 0.8±0.3 ppbv near sunset and a minimum of 0.4±0.2 ppbv 4-5 hours after sunrise. Several clear H2O2 diurnal variations have been observed, from which a first-order removal rate of about 1×10-5 s-1 for H2O2 can be inferred from nighttime measurements. This rate compares well with those deduced from measurements taken at Cape Grim (Tasmania, 41°S) and during the Soviet-American Gas and Aerosol III experiment (equatorial Pacific Ocean).

  19. Computer program for solving compressible nonsimilar-boundary-layer equations for laminar, transitional, or turbulent flows of a perfect gas

    NASA Technical Reports Server (NTRS)

    Price, J. M.; Harris, J. F.

    1972-01-01

    A computer program is described which solves the compressible laminar, transitional, or turbulent boundary-layer equations for planar or axisymmetric flows. Three-point implicit difference relations are used to reduce the momentum and energy equations to finite-difference form. These equations are solved simultaneously without iteration. Turbulent flow is treated by the inclusion of either a two-layer eddy-viscosity model or a mixing-length formulation. The eddy conductivity is related to the eddy viscosity through a static turbulent Prandtl number which may be an arbitrary function of the distance from the wall boundary. The transitional boundary layer is treated by the inclusion of an intermittency function which modifies the fully turbulent model. The laminar-boundary-layer equations are recovered when the intermittency is zero, and the fully turbulent equations are solved when the intermittency is unity.

  20. Solid oxide fuel cell with transitioned cross-section for improved anode gas management at the open end

    DOEpatents

    Zafred, Paolo R [Murrysville, PA; Draper, Robert [Pittsburgh, PA

    2012-01-17

    A solid oxide fuel cell (400) is made having a tubular, elongated, hollow, active section (445) which has a cross-section containing an air electrode (452) a fuel electrode (454) and solid oxide electrolyte (456) between them, where the fuel cell transitions into at least one inactive section (460) with a flattened parallel sided cross-section (462, 468) each cross-section having channels (472, 474, 476) in them which smoothly communicate with each other at an interface section (458).

  1. Inference in `poor` languages

    SciTech Connect

    Petrov, S.

    1996-10-01

    Languages with a solvable implication problem but without complete and consistent systems of inference rules (`poor` languages) are considered. The problem of existence of finite complete and consistent inference rule system for a ``poor`` language is stated independently of the language or rules syntax. Several properties of the problem arc proved. An application of results to the language of join dependencies is given.

  2. Rich Donors, Poor Countries

    ERIC Educational Resources Information Center

    Thomas, M. A.

    2012-01-01

    The shifting ideological winds of foreign aid donors have driven their policy towards governments in poor countries. Donors supported state-led development policies in poor countries from the 1940s to the 1970s; market and private-sector driven reforms during the 1980s and 1990s; and returned their attention to the state with an emphasis on…

  3. CO Multi-line Imaging of Nearby Galaxies (COMING). II. Transitions between atomic and molecular gas, diffuse and dense gas, gas and stars in the dwarf galaxy NGC 2976

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Takuya; Kuno, Nario; Sorai, Kazuo; Kaneko, Hiroyuki; Miyamoto, Yusuke; Muraoka, Kazuyuki; Takeda, Miho; Yanagitani, Kazuki; Kishida, Nozomi; Umei, Michiko; Tanaka, Takahiro; Tomiyasu, Yuto; Nakanishi, Hiroyuki; Saita, Chey; Ueno, Saeko; Salak, Dragan; Matsumoto, Naoko; Morokuma-Matsui, Kana; Pan, Hsi-An; Nakai, Naomasa

    2017-08-01

    In this study, we present the results of 12CO(J = 1-0), 13CO(J = 1-0), and C18O(J = 1-0) simultaneous observations of the dwarf galaxy NGC 2976 conducted as a part of the CO Multi-line Imaging of Nearby Galaxies (COMING) project using the Nobeyama 45 m telescope. We investigated the properties of the molecular gas and star formation in NGC 2976. We found that the molecular gas fraction depends on the surface densities of the total gas and the star formation rate, according to the main stellar disks of spiral galaxies. The ratio of 12CO(J = 3-2) to 12CO(J = 1-0) implies that the temperature of the molecular gas increases with decreases in the surface density of molecular gas. We detected 13CO(J = 1-0) by using the stacking method. The ratio between the integrated intensities of 12CO(J = 1-0) and 13CO(J = 1-0) was 27 ± 11. These ratios imply that the diffuse gas phase is dominant in low surface density regimes. We obtained a lower limit of the ratio between the integrated intensities of 12CO(J = 1-0) and C18O(J = 1-0) of 21. The relation between the surface densities of the total gas and the star formation rate followed a power-law index of 2.08 ± 0.11, which was larger than that between the surface densities of the molecular gas and the star formation rate (1.62 ± 0.17). The steep slope in the relation between the surface densities of the total gas and the star formation rate can be attributed to the rapid increase in the fraction of molecular gas at the surface density of ∼ 10 M⊙. The kinematics of the molecular gas suggest that the bar-like feature rotates with a rigid-body rotation curve rather than a certain pattern speed.

  4. Constraining the Evolution of Poor Clusters

    NASA Astrophysics Data System (ADS)

    Broming, Emma J.; Fuse, C. R.

    2012-01-01

    There currently exists no method by which to quantify the evolutionary state of poor clusters (PCs). Research by Broming & Fuse (2010) demonstrated that the evolution of Hickson compact groups (HCGs) are constrained by the correlation between the X-ray luminosities of point sources and diffuse gas. The current investigation adopts an analogous approach to understanding PCs. Plionis et al. (2009) proposed a theory to define the evolution of poor clusters. The theory asserts that cannibalism of galaxies causes a cluster to become more spherical, develop increased velocity dispersion and increased X-ray temperature and gas luminosity. Data used to quantify the evolution of the poor clusters were compiled across multiple wavelengths. The sample includes 162 objects from the WBL catalogue (White et al. 1999), 30 poor clusters in the Chandra X-ray Observatory archive, and 15 Abell poor clusters observed with BAX (Sadat et al. 2004). Preliminary results indicate that the cluster velocity dispersion and X-ray gas and point source luminosities can be used to highlight a weak correlation. An evolutionary trend was observed for multiple correlations detailed herein. The current study is a continuation of the work by Broming & Fuse examining point sources and their properties to determine the evolutionary stage of compact groups, poor clusters, and their proposed remnants, isolated ellipticals and fossil groups. Preliminary data suggests that compact groups and their high-mass counterpart, poor clusters, evolve along tracks identified in the X-ray gas - X-ray point source relation. While compact groups likely evolve into isolated elliptical galaxies, fossil groups display properties that suggest they are the remains of fully coalesced poor clusters.

  5. Molecular Gas In Young Debris Disks

    NASA Astrophysics Data System (ADS)

    Moór, Attila

    2016-07-01

    Debris disks are generally thought to be the gas poor descendants of protoplanetary disks. While this characteristic may be true for most debris systems, recent surveys in rotational transitions of carbon monoxide led to a growing sample of debris disks where gas has been detected. The origin of gas in these disks is unclear yet. It may be secondary, i.e., similarly to dust grains it is continuously replenished via erosion of larger bodies. However, because of their youth, one cannot exclude that some disks may be hybrid in the sense that they retain their residual primordial gas, while the dust component may predominantly be second generation. The first observations of gaseous debris disks with ALMA provided examples of both types. This talk will review the currently known CO-rich debris disks with special emphasis on the origin of gas and on the commonly shared disk/host star properties.

  6. Structure and Gas-Phase Thermochemistry of a Pd/Cu Complex: Studies on a Model for Transmetalation Transition States.

    PubMed

    Oeschger, Raphael J; Chen, Peter

    2017-01-25

    A heterobimetallic Pd(II)/Cu(I) complex was prepared and characterized by X-ray diffraction analysis. The crystal structure shows a remarkably short Pd-Cu bond and a trigonal ipso carbon atom. The Pd-Cu interaction, as determined by energy-resolved collision-induced dissociation cross-section experiments, models the net stabilizing energy of the Pd-Cu interaction in the transition state of the transmetalation step in Pd/Cu-catalyzed cross-coupling reactions. The bonding situation in the bimetallic dinuclear complex has been studied by atoms-in-molecules analysis.

  7. Poorly controlled gout: who is doing poorly?

    PubMed Central

    Chia, Faith Li-Ann

    2016-01-01

    Gout, an inflammatory arthritis caused by the deposition of monosodium urate crystals, is commonly seen in primary care and specialist clinics. In recent years, there has been a resurgence of interest in gout due to advances in therapies and the understanding of pathophysiology, with new guidelines being published by international bodies. However, there is still a gap between the goals of treatment and actual day-to-day practice. Barriers that result in poorly controlled gout include patient factors such as lack of understanding of the disease, stigma and nonadherence to treatment, as well as physician factors such as knowledge gaps, inadequate use of allopurinol and lack of ownership of the disease. The medical profession needs to do more to bridge the gap through physician and patient education, identification of treatment targets with appropriate use of drugs, and dissemination of guidelines. PMID:27549096

  8. Poorly controlled gout: who is doing poorly?

    PubMed

    Chia, Faith Li-Ann

    2016-08-01

    Gout, an inflammatory arthritis caused by the deposition of monosodium urate crystals, is commonly seen in primary care and specialist clinics. In recent years, there has been a resurgence of interest in gout due to advances in therapies and the understanding of pathophysiology, with new guidelines being published by international bodies. However, there is still a gap between the goals of treatment and actual day-to-day practice. Barriers that result in poorly controlled gout include patient factors such as lack of understanding of the disease, stigma and nonadherence to treatment, as well as physician factors such as knowledge gaps, inadequate use of allopurinol and lack of ownership of the disease. The medical profession needs to do more to bridge the gap through physician and patient education, identification of treatment targets with appropriate use of drugs, and dissemination of guidelines. Copyright: © Singapore Medical Association.

  9. Atomic-to-Molecular Gas Transition in Nearby Galaxies: What can we learn from the CARMA Survey Toward IR-bright Nearby Galaxies (STING)?

    NASA Astrophysics Data System (ADS)

    Xue, Rui; Wong, Tony

    2011-10-01

    We present a detailed comparison of molecular and atomic gas distributions in 18 nearby galaxies at sub-kpc or kpc scales, based on the CO J = 1 - 0 data from the CARMA Survey Toward IR-Bright Nearby Galaxies (STING) and the HI 21cm data in the NRAO Very Large Array (VLA) archive. The observation spatial coverage extends to a quarter of the optical radius for each galaxy. The average molecular and atomic gas column density sensitivities are ~8M⊙/pc2 and ~3M⊙/pc2 at the comparison resolution. A metallicity dependence of the HI saturation limit was possibly detected in the galaxy sample ( 8.1<12+Log(O/H)<9.0 ). We used the CO and HI pixel-by-pixel comparison results to test models of the atomic-to-molecular transition and CO formation at different metallicities. An acceptable agreement was found at the limited spatial resolutions and sensitivities of the observational datasets.

  10. Development of novel low-temperature selective hydrogen gas sensors made of palladium/oxide or nitride capped Magnesium-transition metal hydride films

    NASA Astrophysics Data System (ADS)

    Tang, Yu Ming

    Palladium capped Mg-based transition metal alloy film (Pd/Mg-TM) is a potentially useful hydrogen gas (H2) sensing material, which can operate at low temperature for detection of H2 leakage in an environment to ensure safe use and storage of the gas. The Pd layer catalytically dissociates hydrogen molecules, and the hydrogen atoms produced can enter (hydridation) or be detached (dehydridation) from the alloy layer. These processes are reversible, such that the film is switchable between a metal state and a hydride state, giving rise to substantial changes in its optical transmittance/reflectance and electrical resistivity. Unlike a conventional metal-oxide (MOx) H2 sensor, hydridation of an Mg-TM film is associated with relatively low enthalpy, and hence can perform at temperature much lower than the operation temperature of an MOx sensor (typically around 500°C or above). As such, an Mg-TM based sensor does not experience undesired annealing effect during operation, and hence is much more stable and durable. Furthermore, the detection selectivity of a Pd/Mg-TM film versus other reducing gases is superior to most conventional MOx-type hydrogen sensors. In this project, we systematically investigated the H2 sensing properties of Pd/Mg-TM films.

  11. Direct reduction of carbon dioxide to formate in high-gas-capacity ionic liquids at post-transition-metal electrodes.

    PubMed

    Watkins, John D; Bocarsly, Andrew B

    2014-01-01

    As an approach to combat the increasing emissions of carbon dioxide in the last 50 years, the sequestration of carbon dioxide gas in ionic liquids has become an attractive research area. Ionic liquids can be made that possess incredibly high molar absorption and specificity characteristics for carbon dioxide. Their high carbon dioxide solubility and specificity combined with their high inherent electrical conductivity also creates an ideal medium for the electrochemical reduction of carbon dioxide. Herein, a lesser studied ionic liquid, 1-ethyl-3-methylimidazolium trifluoroacetate, was used as both an effective carbon dioxide capture material and subsequently as an electrochemical matrix with water for the direct reduction of carbon dioxide into formate at indium, tin, and lead electrodes in good yield (ca. 3 mg h(-1) cm(-2)).

  12. Poor school performance.

    PubMed

    Karande, Sunil; Kulkarni, Madhuri

    2005-11-01

    Education is one of the most important aspects of human resource development. Poor school performance not only results in the child having a low self-esteem, but also causes significant stress to the parents. There are many reasons for children to under perform at school, such as, medical problems, below average intelligence, specific learning disability, attention deficit hyperactivity disorder, emotional problems, poor socio-cultural home environment, psychiatric disorders and even environmental causes. The information provided by the parents, classroom teacher and school counselor about the child's academic difficulties guides the pediatrician to form an initial diagnosis. However, a multidisciplinary evaluation by an ophthalmologist, otolaryngologist, counselor, clinical psychologist, special educator, and child psychiatrist is usually necessary before making the final diagnosis. It is important to find the reason(s) for a child's poor school performance and come up with a treatment plan early so that the child can perform up to full potential.

  13. Role of single-point mutations and deletions on transition temperatures in ideal proteinogenic heteropolymer chains in the gas phase.

    PubMed

    Olivares-Quiroz, L

    2016-07-01

    A coarse-grained statistical mechanics-based model for ideal heteropolymer proteinogenic chains of non-interacting residues is presented in terms of the size K of the chain and the set of helical propensities [Formula: see text] associated with each residue j along the chain. For this model, we provide an algorithm to compute the degeneracy tensor [Formula: see text] associated with energy level [Formula: see text] where [Formula: see text] is the number of residues with a native contact in a given conformation. From these results, we calculate the equilibrium partition function [Formula: see text] and characteristic temperature [Formula: see text] at which a transition from a low to a high entropy states is observed. The formalism is applied to analyze the effect on characteristic temperatures [Formula: see text] of single-point mutations and deletions of specific amino acids [Formula: see text] along the chain. Two probe systems are considered. First, we address the case of a random heteropolymer of size K and given helical propensities [Formula: see text] on a conformational phase space. Second, we focus our attention to a particular set of neuropentapeptides, [Met-5] and [Leu-5] enkephalins whose thermodynamic stability is a key feature on their coupling to [Formula: see text] and [Formula: see text] receptors and the triggering of biochemical responses.

  14. Transition from gas-kinetic to minimal metal-type conductivity in a supercritical fluid of metal vapor

    NASA Astrophysics Data System (ADS)

    Khomkin, A. L.; Shumikhin, A. S.

    2017-06-01

    We have proposed a peculiar model of the plasma of dense metal vapors, containing atoms embedded into the electron jelly, as well as free (thermally ionized) electrons and ions. The main feature of the model is the presence of the electron jelly existing at any density of the atomic component. The number of electrons in the jelly increases under compression. The process of its formation can be called the "cold" ionization, or pressure ionization. The composition of the gas-plasma mixture, including the concentration of atoms and electrons in the jelly, as well as the concentration of free thermally ionized electrons and ions, has been calculated. The conductivity of dense vapors is determined by the sum of the conductivities of thermal electrons (which is calculated using the Frost formula) and jelly electrons (which is calculated by the Regel-Ioffe formula for the minimal metal-type conductivity). The concentration of thermal electrons decreases and the concentration of jelly electrons increases upon compression of the vapor. Accordingly, the conductivity varies from the conductivity of thermal electrons to the conductivity of jelly electrons, continuously passing through the minimum. The calculated values of the conductivity of supercritical metal vapors are in satisfactory agreement with experimental results.

  15. Aerosol size distribution and aerosol water content measurements during Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Sievering, H.; Boatman, J.; Wellman, D.; Pszenny, A.

    1995-11-01

    Aerosol size distribution data measured during the June 1992 Marine Aerosol and Gas Exchange experiment are analyzed to investigate the characteristics of fine marine aerosol particles measured over the North Atlantic near the Azores Islands. Measured aerosol size distribution data were corrected using the corrected size calibration data based on the optical properties of particles being measured. The corrected size distribution data were then approximated with either one or two lognormal size distributions, depending on air mass conditions. Under clean air mass conditions <3 μm diameter aerosol size distributions typically exhibited two modes, consisting of an accumulation mode and the small end of the sea-salt particle mode. However, under the influence of continental polluted air masses, the aerosol size distribution was dominated by <1 μm diameter particles in a single mode with an increased aerosol concentration. Aerosol water content of accumulation mode marine aerosols was estimated from differences between several series of ambient and dried aerosol size distributions. The average aerosol water fraction was 0.31, which is in good agreement with an empirical aerosol growth model estimate. The average rate of SO4= production in the accumulation mode aerosol water by H2O2 oxidation was estimated to be <7×10-10 mol L-1 s-1, which is an insignificant contributor to the observed non-sea-salt SO4= in the accumulation mode.

  16. Cooper pairs with zero center-of-mass momentum and their first-order correlation function in a two-dimensional ultracold Fermi gas near a Berezinskii-Kosterlitz-Thouless transition

    NASA Astrophysics Data System (ADS)

    Matsumoto, Morio; Inotani, Daisuke; Ohashi, Yoji

    2016-01-01

    We investigate the center-of-mass momentum distribution nQ of Cooper pairs and their first-order correlation function g1(r ) in a strongly interacting two-dimensional Fermi gas. Recently, the Berezinskii-Kosterlitz-Thouless (BKT) transition was reported in a two-dimensional 6Li Fermi gas, based on (1) the observations of anomalous enhancement of nQ =0 [Ries et al., Phys. Rev. Lett. 114, 230401 (2015), 10.1103/PhysRevLett.114.230401] , as well as (2) a power-law behavior of g1(r ) [Murthy et al., Phys. Rev. Lett. 115, 010401 (2015), 10.1103/PhysRevLett.115.010401]. However, including pairing fluctuations within a T -matrix approximation (TMA), we show that these results can still be explained as strong-coupling properties of a normal-state two-dimensional Fermi gas. Our results indicate the importance of further experimental observations, to definitely confirm the realization of the BKT transition in this system. Since the BKT transition has been realized in a two-dimensional ultracold Bose gas, our results would be useful for the achievement of this quasi-long-range order in an ultracold Fermi gas.

  17. Confronting Poor Performance.

    ERIC Educational Resources Information Center

    Dennis, Bruce L.

    Responsible and effective administrative leadership requires confronting those members of the teaching staff who are a negative influence on the institution. Importantly, the absence of expressed appreciation for good work can have a devastating impact on a principal's image if he or she suddenly begins to confront poor performances. Actually, the…

  18. The Poor Pay More.

    ERIC Educational Resources Information Center

    Folse, Kimberly A.

    2002-01-01

    Describes a sociology experiential learning assignment where students learned why people living in poverty can sometimes pay more for products than people with better incomes. Focuses specifically on the rent to own concept. States students achieved the goal of learning how life constraints of poverty can hinder the poor from overcoming their…

  19. The Poor Pay More.

    ERIC Educational Resources Information Center

    Folse, Kimberly A.

    2002-01-01

    Describes a sociology experiential learning assignment where students learned why people living in poverty can sometimes pay more for products than people with better incomes. Focuses specifically on the rent to own concept. States students achieved the goal of learning how life constraints of poverty can hinder the poor from overcoming their…

  20. GROWING UP POOR.

    ERIC Educational Resources Information Center

    CHILMAN, CATHERINE S.

    PRIMARILY AN OVERVIEW AND ANALYSIS OF RESEARCH ON CHILD-REARING AND FAMILY LIFE PATTERNS, THIS BOOK FOCUSES ON THE LIFE OF THE VERY POOR AND COMPARES THEIR LIFE PATTERNS AND PRACTICES WITH THOSE OF MIDDLE-CLASS FAMILIES. THE TWO SETS OF PATTERNS ARE ANALYZED UNDER FIVE HEADINGS--MENTAL HEALTH, EDUCATION, "MORAL" CHARACTER, SOCIAL ACCEPTABILITY,…

  1. Morphosyntax in Poor Comprehenders

    ERIC Educational Resources Information Center

    Adlof, Suzanne M.; Catts, Hugh W.

    2015-01-01

    Children described as "poor comprehenders" (PCs) have reading comprehension difficulties in spite of adequate word reading abilities. PCs are known to display weakness with semantics and higher-level aspects of oral language, but less is known about their grammatical skills, especially with regard to morphosyntax. The purpose of this…

  2. Gas sorption and transition-metal cation separation with a thienothiophene based zirconium metal–organic framework

    SciTech Connect

    SK, Mostakim; Grzywa, Maciej; Volkmer, Dirk; Biswas, Shyam

    2015-12-15

    The modulated synthesis of the thienothiophene based zirconium metal–organic framework (MOF) material having formula [Zr{sub 6}O{sub 4}(OH){sub 4}(DMTDC){sub 6}]·4.8DMF·10H{sub 2}O (1) (H{sub 2}DMTDC=3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid; DMF=N,N'-dimethylformamide) was carried out by heating a mixture of ZrCl{sub 4}, H{sub 2}DMTDC linker and benzoic acid (used as a modulator) with a molar ratio of 1:1:30 in DMF at 150 °C for 24 h. Systematic investigations have been performed in order to realize the effect of ZrCl{sub 4}/benzoic acid molar ratio on the crystallinity of the material. The activation (i.e., the removal of the guest solvent molecules from the pores) of as-synthesized compound was achieved by stirring it with methanol and subsequently heating under vacuum. A combination of X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric (TG) and elemental analysis was used to examine the phase purity of the as-synthesized and thermally activated 1. The material displays high thermal stability up to 310 °C in an air atmosphere. As revealed from the XRD measurements, the compound retains its crystallinity when treated with water, acetic acid and 1 M HCl solutions. The N{sub 2} and CO{sub 2} sorption analyses suggest that the material possesses remarkably high microporosity (S{sub BET}=1236 m{sup 2} g{sup −1}; CO{sub 2} uptake=3.5 mmol g{sup −1} at 1 bar and 0 °C). The compound also shows selective adsorption behavior for Cu{sup 2+} over Co{sup 2+} and Ni{sup 2+} ions. - Graphical abstract: Selective transition-metal cation adsorption by a thienothiophene based zirconium metal–organic framework material. - Highlights: • The modulated synthesis of a thienothiophene based Zr(IV) MOF has been described. • Effect of metal salt/modulator ratio on the crystallinity was thoroughly studied. • The compound showed high thermal and physiochemical stability. • N{sub 2} and CO{sub 2} sorption experiments revealed

  3. Nitrogen dioxide reactions with 46 atomic main-group and transition metal cations in the gas phase: room temperature kinetics and periodicities in reactivity.

    PubMed

    Jarvis, Michael J Y; Blagojevic, Voislav; Koyanagi, Gregory K; Bohme, Diethard K

    2013-02-14

    Experimental results are reported for the gas-phase room-temperature kinetics of chemical reactions between nitrogen dioxide (NO(2)) and 46 atomic main-group and transition metal cations (M(+)). Measurements were taken with an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer in helium buffer gas at a pressure of 0.35 ± 0.01 Torr and at 295 ± 2 K. The atomic cations were produced at ca. 5500 K in an ICP source and allowed to decay radiatively and to thermalize to room temperature by collisions with Ar and He atoms prior to reaction with NO(2). Measured apparent bimolecular rate coefficients and primary reaction product distributions are reported for all 46 atomic metal cations and these provide an overview of trends across and down the periodic table. Three main types of reactions were observed: O-atom transfer to form either MO(+) or NO(+), electron transfer to form NO(2)(+), and addition to form MNO(2)(+). Bimolecular O-atom transfer was observed to predominate. Correlations are presented between reaction efficiency and the O-atom affinity of the metal cation and between the prevalence of NO(+) product formation and the electron recombination energy of the product metal oxide cation. Some second-order reactions are evident with metal cations that react inefficiently. Most interesting of these is the formation of the MNO(+) cation with Rh(+) and Pd(+). The higher-order chemistry with NO(2) is very diverse and includes the formation of numerous NO(2) ion clusters and a number of tri- and tetraoxide metal cations. Group 2 metal dioxide cations (CaO(2)(+), SrO(2)(+), BaO(2)(+)) exhibit a unique reaction with NO(2) to form MO(NO)(+) ions perhaps by NO transfer from NO(2) concurrent with O(2) formation by recombination of a NO(2) and an oxide oxygen.

  4. Letting the poor speak.

    PubMed

    2000-09-29

    This paper comments on two documents prepared by the Washington-based World Bank: the "World Development Report" and the three-volume study "Voices of the Poor." The author provides a brief overview of these documents then examines their potential impact on the delegates to the annual meetings of the World Bank and the International Monetary Fund in Prague on September 19-28, 2000. The author further examines the implication of the new strategies embraced by the global lenders--"opportunity, empowerment, security." Apart from these strategies, the World Bank sets out other strategies like spreading the benefits of technology, as it calls for the elimination of absolute poverty by 2015. However, the most crucial tack is the one illustrated by the way the reports were made: letting the poor speak and responding to their cries.

  5. Landau levels and spin splitting in the two-dimensional electron gas of a HgTe quantum well near the critical width for the topological phase transition

    NASA Astrophysics Data System (ADS)

    Pakmehr, M.; Bruene, C.; Buhmann, H.; Molenkamp, L. W.; Stier, A. V.; McCombe, B. D.

    2014-12-01

    We report a detailed low-temperature study of the two-dimensional (2D) electron gas in a 6.1-nm-wide HgTe quantum well with H g0.3C d0.7Te barriers by terahertz magnetophotoconductivity and magnetotransmission combined with magnetotransport measurements (Rx x and Rx y) in magnetic fields up to 10 T. This well width, close to that at the topological phase transition, corresponds to conventional band ordering, and we probe the "bulk" quasi-2D Landau-level (LL) spectrum of the conduction band at high energies (≈135 -160 meV ) above the Dirac point. The calculated separations between adjacent LLs of the same spin based on published parameters for this structure are in fair agreement with the measured cyclotron resonance energies. However, the very large spin splittings observed (Espin>Ecyclotron) require a significantly larger g -parameter ge for electrons. Tilted field coincidence experiments are consistent with the large spin splitting showing coincidences at 3/2 and twice the cyclotron energy. This large value of ge also leads to interesting crossings of the calculated LLs, and we find direct evidence of these crossings in the Rx x measurements at lower electron densities (Fermi energies) produced by negative gate bias.

  6. Alternative fuel transit buses: The Pierce Transit Success Story

    SciTech Connect

    1996-10-01

    The Pierce transit program for operating mass transit buses on compressed natural gas (CNG) is described. Cost, reliability, fuel efficiency, emission of combustion products, and future trends are discussed.

  7. Emissions of toxic pollutants from compressed natural gas and low sulfur diesel-fueled heavy-duty transit buses tested over multiple driving cycles.

    PubMed

    Kado, Norman Y; Okamoto, Robert A; Kuzmicky, Paul A; Kobayashi, Reiko; Ayala, Alberto; Gebel, Michael E; Rieger, Paul L; Maddox, Christine; Zafonte, Leo

    2005-10-01

    The number of heavy-duty vehicles using alternative fuels such as compressed natural gas (CNG) and new low-sulfur diesel fuel formulations and equipped with after-treatment devices are projected to increase. However, few peer-reviewed studies have characterized the emissions of particulate matter (PM) and other toxic compounds from these vehicles. In this study, chemical and biological analyses were used to characterize the identifiable toxic air pollutants emitted from both CNG and low-sulfur-diesel-fueled heavy-duty transit buses tested on a chassis dynamometer over three transient driving cycles and a steady-state cruise condition. The CNG bus had no after-treatment, and the diesel bus was tested first equipped with an oxidation catalyst (OC) and then with a catalyzed diesel particulate filter (DPF). Emissions were analyzed for PM, volatile organic compounds (VOCs; determined on-site), polycyclic aromatic hydrocarbons (PAHs), and mutagenic activity. The 2000 model year CNG-fueled vehicle had the highest emissions of 1,3-butadiene, benzene, and carbonyls (e.g., formaldehyde) of the three vehicle configurations tested in this study. The 1998 model year diesel bus equipped with an OC and fueled with low-sulfur diesel had the highest emission rates of PM and PAHs. The highest specific mutagenic activities (revertants/microg PM, or potency) and the highest mutagen emission rates (revertants/mi) were from the CNG bus in strain TA98 tested over the New York Bus (NYB) driving cycle. The 1998 model year diesel bus with DPF had the lowest VOCs, PAH, and mutagenic activity emission. In general, the NYB driving cycle had the highest emission rates (g/mi), and the Urban Dynamometer Driving Schedule (UDDS) had the lowest emission rates for all toxics tested over the three transient test cycles investigated. Also, transient emissions were, in general, higher than steady-state emissions. The emissions of toxic compounds from an in-use CNG transit bus (without an oxidation

  8. Poor ovarian reserve

    PubMed Central

    Jirge, Padma Rekha

    2016-01-01

    Poor ovarian reserve (POR) is an important limiting factor for the success of any treatment modality for infertility. It indicates a reduction in quantity and quality of oocytes in women of reproductive age group. It may be age related as seen in advanced years of reproductive life or may occur in young women due to diverse etiological factors. Evaluating ovarian reserve and individualizing the therapeutic strategies are very important for optimizing the success rate. Majority or women with POR need to undergo in vitro fertilization to achieve pregnancy. However, pregnancy rate remains low despite a plethora of interventions and is associated with high pregnancy loss. Early detection and active management are essential to minimize the need for egg donation in these women. PMID:27382229

  9. Theoretical studies on the catalysis of the reverse water-gas shift reaction using first-row transition metal beta-diketiminato complexes.

    PubMed

    Liu, Cong; Munjanja, Lloyd; Cundari, Thomas R; Wilson, Angela K

    2010-06-03

    The reverse water-gas shift reaction CO(2) + H(2) --> H(2)O + CO has been investigated using a set of homogeneous catalyst models L'M(I) (L' = beta-diketiminate, C(3)N(2)H(5)(-); M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn). The thermodynamics of prototypical reaction pathways were simulated at two levels of theory: B3LYP/6-311+G(d) and B3LYP/aug-cc-pVTZ. The modeled catalytic reaction has been considered in the following steps: coordination of CO(2) by the catalyst to generate a carbon dioxide complex, L'M(CO(2)); scission of L'M(CO(2)) to yield L'M(CO) and L'M(O); L'M(O) hydrogenation to form L'M(H(2)O). The final products, H(2)O and CO, were obtained from the dissociation of L'M(H(2)O) and L'M(CO). All of the reactants, intermediates, and products were modeled, where different possible conformers and multiplicities were identified and considered as potential minima. The reaction enthalpy DeltaH, of all steps for each catalyst as a function of transition metal have been determined. The Mn and Fe catalysts show more thermodynamically accessible pathways than the other catalyst models studied. The overall reaction enthalpy has been determined not only by B3LYP/6-311+G(d) and B3LYP/aug-cc-pVTZ but also via a more rigorous ab initio electron-correlation-based approach, the correlation consistent Composite Approach (ccCA).

  10. Morphosyntax in Poor Comprehenders

    PubMed Central

    Adlof, Suzanne M.; Catts, Hugh W.

    2016-01-01

    Children described as poor comprehenders (PCs) have reading comprehension difficulties in spite of adequate word reading abilities. PCs are known to display weakness with semantics and higher-level aspects of oral language, but less is known about their grammatical skills, especially with regard to morphosyntax. The purpose of this study was to examine morphosyntax in fourth grade PCs and typically developing readers (TDs), using three experimental tasks involving finiteness marking. Participants also completed standardized, norm-referenced assessments of phonological memory, vocabulary, and broader language skills. PCs displayed weakness relative to TDs on all three morphosyntax tasks and on every other assessment of oral language except phonological memory, as indexed by nonword repetition. These findings help to clarify the linguistic profile of PCs, suggesting that their language weaknesses include grammatical weaknesses that cannot be fully explained by semantic factors. Because finiteness markers are usually mastered prior to formal schooling in typical development, we call for future studies to examine whether assessments of morphosyntax could be used for the early identification of children at risk for future reading comprehension difficulty. PMID:27397969

  11. A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614 . Further evidence for a giant planet inside the disk?

    NASA Astrophysics Data System (ADS)

    Carmona, A.; Thi, W. F.; Kamp, I.; Baruteau, C.; Matter, A.; van den Ancker, M.; Pinte, C.; Kóspál, A.; Audard, M.; Liebhart, A.; Sicilia-Aguilar, A.; Pinilla, P.; Regály, Zs.; Güdel, M.; Henning, Th.; Cieza, L. A.; Baldovin-Saavedra, C.; Meeus, G.; Eiroa, C.

    2017-02-01

    Context. Quantifying the gas surface density inside the dust cavities and gaps of transition disks is important to establish their origin. Aims: We seek to constrain the surface density of warm gas in the inner disk of HD 139614, an accreting 9 Myr Herbig Ae star with a (pre-)transition disk exhibiting a dust gap from 2.3 ± 0.1 to 5.3 ± 0.3 AU. Methods: We observed HD 139614 with ESO/VLT CRIRES and obtained high-resolution (R 90 000) spectra of CO ro-vibrational emission at 4.7 μm. We derived constraints on the disk's structure by modeling the CO isotopolog line-profiles, the spectroastrometric signal, and the rotational diagrams using grids of flat Keplerian disk models. Results: We detected υ = 1 → 0 12CO, 2→1 12CO, 1→0 13CO, 1→0 C18O, and 1→0 C17O ro-vibrational lines. Lines are consistent with disk emission and thermal excitation. 12CO υ = 1 → 0 lines have an average width of 14 km s-1, Tgas of 450 K and an emitting region from 1 to 15 AU. 13CO and C18O lines are on average 70 and 100 K colder, 1 and 4 km s-1 narrower than 12CO υ = 1 → 0, and are dominated by emission at R ≥ 6 AU. The 12CO υ = 1 → 0 composite line-profile indicates that if there is a gap devoid of gas it must have a width narrower than 2 AU. We find that a drop in the gas surface density (δgas) at R < 5-6 AU is required to be able to simultaneously reproduce the line-profiles and rotational diagrams of the three CO isotopologs. Models without a gas density drop generate 13CO and C18O emission lines that are too broad and warm. The value of δgas can range from 10-2 to 10-4 depending on the gas-to-dust ratio of the outer disk. We find that the gas surface density profile at 1 < R < 6 AU is flat or increases with radius. We derive a gas column density at 1 < R < 6 AU of NH = 3 × 1019-1021 cm-2 (7 × 10-5-2.4 × 10-3 g cm-2) assuming NCO = 10-4NH. We find a 5σ upper limit on the CO column density NCO at R ≤ 1 AU of 5 × 1015 cm-2 (NH ≤ 5 × 1019 cm-2). Conclusions

  12. Improvement of Gas-Sensing Performance of Large-Area Tungsten Disulfide Nanosheets by Surface Functionalization.

    PubMed

    Ko, Kyung Yong; Song, Jeong-Gyu; Kim, Youngjun; Choi, Taejin; Shin, Sera; Lee, Chang Wan; Lee, Kyounghoon; Koo, Jahyun; Lee, Hoonkyung; Kim, Jongbaeg; Lee, Taeyoon; Park, Jusang; Kim, Hyungjun

    2016-10-05

    Semiconducting two-dimensional (2D) transition metal dichalcogenides (TMDCs) are promising gas-sensing materials due to their large surface-to-volume ratio. However, their poor gas-sensing performance resulting from the low response, incomplete recovery, and insufficient selectivity hinders the realization of high-performance 2D TMDC gas sensors. Here, we demonstrate the improvement of gas-sensing performance of large-area tungsten disulfide (WS2) nanosheets through surface functionalization using Ag nanowires (NWs). Large-area WS2 nanosheets were synthesized through atomic layer deposition of WO3 followed by sulfurization. The pristine WS2 gas sensors exhibited a significant response to acetone and NO2 but an incomplete recovery in the case of NO2 sensing. After AgNW functionalization, the WS2 gas sensor showed dramatically improved response (667%) and recovery upon NO2 exposure. Our results establish that the proposed method is a promising strategy to improve 2D TMDC gas sensors.

  13. Deep Reductions in Greenhouse Gas Emissions from the California Transportation Sector: Dynamics in Vehicle Fleet and Energy Supply Transitions to Achieve 80% Reduction in Emissions from 1990 Levels by 2050

    NASA Astrophysics Data System (ADS)

    Leighty, Wayne Waterman

    California's "80in50" target for reducing greenhouse gas emissions to 80 percent below 1990 levels by the year 2050 is based on climate science rather than technical feasibility of mitigation. As such, it raises four fundamental questions: is this magnitude of reduction in greenhouse gas emissions possible, what energy system transitions over the next 40 years are necessary, can intermediate policy goals be met on the pathway toward 2050, and does the path of transition matter for the objective of climate change mitigation? Scenarios for meeting the 80in50 goal in the transportation sector are modelled. Specifically, earlier work defining low carbon transport scenarios for the year 2050 is refined by incorporating new information about biofuel supply. Then transition paths for meeting 80in50 scenarios are modelled for the light-duty vehicle sub-sector, with important implications for the timing of action, rate of change, and cumulative greenhouse gas emissions. One aspect of these transitions -- development in the California wind industry to supply low-carbon electricity for plug-in electric vehicles -- is examined in detail. In general, the range of feasible scenarios for meeting the 80in50 target is narrow enough that several common themes are apparent: electrification of light-duty vehicles must occur; continued improvements in vehicle efficiency must be applied to improving fuel economy; and energy carriers must de-carbonize to less than half of the carbon intensity of gasoline and diesel. Reaching the 80in50 goal will require broad success in travel demand reduction, fuel economy improvements and low-carbon fuel supply, since there is little opportunity to increase emission reductions in one area if we experience failure in another. Although six scenarios for meeting the 80in50 target are defined, only one also meets the intermediate target of reducing greenhouse gas emissions to 1990 levels by the year 2020. Furthermore, the transition path taken to reach any

  14. Consequences of Growing Up Poor.

    ERIC Educational Resources Information Center

    Duncan, Greg J., Ed.; Brooks-Gunn, Jeanne, Ed.

    The consequences and correlates of growing up poor as well as the mechanisms through which poverty influences children are explored. This book is organized with a primary focus on research findings and a secondary concern with policy implications. The chapters are: (1) "Poor Families, Poor Outcomes: The Well-Being of Children and Youth" (Jeanne…

  15. Consequences of Growing Up Poor.

    ERIC Educational Resources Information Center

    Duncan, Greg J., Ed.; Brooks-Gunn, Jeanne, Ed.

    The consequences and correlates of growing up poor as well as the mechanisms through which poverty influences children are explored. This book is organized with a primary focus on research findings and a secondary concern with policy implications. The chapters are: (1) "Poor Families, Poor Outcomes: The Well-Being of Children and Youth" (Jeanne…

  16. Gas Emissions in Planck Cold Dust Clumps—A Survey of the J = 1-0 Transitions of 12CO, 13CO, and C18O

    NASA Astrophysics Data System (ADS)

    Wu, Yuefang; Liu, Tie; Meng, Fanyi; Li, Di; Qin, Sheng-Li; Ju, Bing-Gang

    2012-09-01

    A survey toward 674 Planck cold clumps of the Early Cold Core Catalogue (ECC) in the J = 1-0 transitions of 12CO, 13CO, and C18O has been carried out using the Purple Mountain Observatory 13.7 m telescope. Six hundred seventy-three clumps were detected with 12CO and 13CO emission, and 68% of the sample has C18O emission. Additional velocity components were also identified. A close consistency of the three line peak velocities was revealed for the first time. Kinematic distances are given for all the velocity components, and half of the clumps are located within 0.5 and 1.5 kpc. Excitation temperatures range from 4 to 27 K, slightly larger than those of Td . Line width analysis shows that the majority of ECC clumps are low-mass clumps. Column densities N_{H_{2}} span from 1020 to 4.5 × 1022 cm-2 with an average value of (4.4 ± 3.6) × 1021 cm-2. N_{H_{2}} cumulative fraction distribution deviates from the lognormal distribution, which is attributed to optical depth. The average abundance ratio of the 13CO to C18O in these clumps is 7.0 ± 3.8, higher than the terrestrial value. Dust and gas are well coupled in 95% of the clumps. Blue profile asymmetry, red profile asymmetry, and total line asymmetry were found in less than 10% of the clumps, generally indicating that star formation is not yet developed. Ten clumps were mapped. Twelve velocity components and 22 cores were obtained. Their morphologies include extended diffuse, dense, isolated, cometary, and filament, of which the last is the majority. Twenty cores are starless, and only seven cores seem to be in a gravitationally bound state. Planck cold clumps are the most quiescent among the samples of weak red IRAS, infrared dark clouds, UC H II candidates, extended green objects, and methanol maser sources, suggesting that Planck cold clumps have expanded the horizon of cold astronomy.

  17. Noble gas paleotemperatures and humidity during the last Glacial - Interglacial transition in Switzerland - first application of the CVCS system to a stalagmite grown under cool climatic conditions

    NASA Astrophysics Data System (ADS)

    Vogel, Nadia; Figura, Simon; Fleitmann, Dominik; Maden, Colin; Wieler, Rainer; Kipfer, Rolf

    2014-05-01

    Stalagmites represent excellent multi-proxy paleoclimate archives as they cover long timescales and can be dated with high precision [1]. We determine noble gas temperatures (NGTs) using the CVCS (Combined Vacuum Crushing and Sieving) technique, which enables to preferentially reduce the air content of stalagmite samples, such that temperature information can be deduced from the noble gases dissolved in the stalagmite's water inclusions [2]. The system allows accurate temperature determination from Ne, Ar, Kr, and Xe, as shown in a cross-calibration study on a stalagmite from Borneo [3,4]. We have now applied the CVCS technique to samples of stalagmite M2 from Milandre Cave (Swiss Jura Mountains), covering the transitions Bølling-Allerød - Younger Dryas (YD) - Preboreal [5]. So far, we have determined three preliminary NGTs, indicating cave temperatures before the onset of the YD of ~3°C, and dropping to ~1°C at the onset of the YD. These temperatures compare well with theoretical mean annual Milandre cave temperatures inferred from summer temperatures deduced from sediments of Gerzensee [6], located south of Milandre. We also determined in 12 M2 samples water contents, which, for samples grown under hot and rather dry climatic conditions provide information about drip water availability [7]: higher water contents point to irregular, low drip rates and vice versa. In M2, water contents increase strongly at the onset of the YD, suggesting a progressively dryer climate. Towards the end of the YD water contents drop again and are very low at the onset of the Preboreal, indicating a return to more humid conditions. The same conclusion was drawn from a M2 carbon isotope record, reflecting reduced discharge and vegetation density due to dryer conditions during the cold period [8]. Our data emphasize the applicability of the water content as a drip rate proxy also for stalagmites grown under cool climatic conditions. [1] Henderson G.M. (2006) Science, 313, 620-622. [2

  18. Simple Model for Vibration-Translation Exchange at High Temperatures: Effects of Multiquantum Transitions on the Relaxation Of A N2 Gas Flow Behind a Shock

    DTIC Science & Technology

    2011-02-22

    relaxation of a N2 gas flow behind a shock A. Aliat,1,* P. Vedula,1,* and E. Josyula2 1School of Aerospace and Mechanical Engineering, University of...influence on the relaxation of the macroscopic parameters of the gas flow behind the shock, especially on vibrational distributions of high levels. All...simulate hypersonic gas flows are based on the assumption of quasistationary distributions (Boltzmann or Treanor) over vibrational energies [2–5]. These

  19. Variational Transition State Theory

    SciTech Connect

    Truhlar, Donald G.

    2016-09-29

    This is the final report on a project involving the development and applications of variational transition state theory. This project involved the development of variational transition state theory for gas-phase reactions, including optimized multidimensional tunneling contributions and the application of this theory to gas-phase reactions with a special emphasis on developing reaction rate theory in directions that are important for applications to combustion. The development of variational transition state theory with optimized multidimensional tunneling as a useful computational tool for combustion kinetics involved eight objectives.

  20. EFFECTS OF FLY ASH TRANSITION METAL CONTENT AND FLUE GAS HCL/SO2 RATIO ON MERCURY SPECIATION IN WASTE COMBUSTION

    EPA Science Inventory

    The paper presents results of research on the effect of sulfur dioxide (SO2):HCI ratio on heterogeneous Hg0 oxidation. The addition of SO2 to moist flue gas at high SO2:HCI ratios (4:1 to 10:1) caused a decrease in oxidation of Hg0 relative to flur gas without SO2. This is attrib...

  1. EFFECTS OF FLY ASH TRANSITION METAL CONTENT AND FLUE GAS HCL/SO2 RATIO ON MERCURY SPECIATION IN WASTE COMBUSTION

    EPA Science Inventory

    The paper presents results of research on the effect of sulfur dioxide (SO2):HCI ratio on heterogeneous Hg0 oxidation. The addition of SO2 to moist flue gas at high SO2:HCI ratios (4:1 to 10:1) caused a decrease in oxidation of Hg0 relative to flur gas without SO2. This is attrib...

  2. On the excited state dynamics of vibronic transitions. High-resolution electronic spectra of acenaphthene and its argon van der Waals complex in the gas phase.

    PubMed

    Álvarez-Valtierra, Leonardo; Plusquellic, David F; Yi, John T; Pratt, David W

    2011-09-01

    Rotationally resolved fluorescence excitation spectroscopy has been used to study the dynamics, electronic distribution, and the relative orientation of the transition moment vector in several vibronic transitions of acenaphthene (ACN) and in its Ar van der Waals (vdW) complex. The 0(0)(0) band of the S(1) ← S(0) transition of ACN exhibits a transition moment orientation parallel to its a-inertial axis. However, some of the vibronic bands exhibit a transition moment orientation parallel to the b-inertial axis, suggesting a Herzberg-Teller coupling with the S(2) state. Additionally, some other vibronic bands exhibit anomalous intensity patterns in several of their rotational transitions. A Fermi resonance involving two near degenerate vibrations has been proposed to explain this behavior. The high-resolution electronic spectrum of the ACN-Ar vdW complex has also been obtained and fully analyzed. The results indicate that the weakly attached argon atom is located on top of the plane of the bare molecule at ~3.48 Å away from its center of mass in the S(0) electronic state. © 2011 American Chemical Society

  3. The Etiology of Poor Neighborhoods.

    ERIC Educational Resources Information Center

    Greenberg, Stanley B.

    The inner city aggregations of blacks, Appalachian whites, and Mexicans are not simply the focal points for short-term instability or remedial governmental programs: they are the first native American urban poor. The poor neighborhoods of America's inner city are a result of three great population movements. One originated in the Atlantic Coastal…

  4. Federal Supervisors and Poor Performers

    DTIC Science & Technology

    1999-07-01

    This report looks at the prevalence of poor performance in the Federal workplace from the perspective of employees and supervisors. The report also...examines what supervisors do about poor performers, the effects of supervisors’ actions, and the factors that influence supervisors’ decisions about how they will handle inadequate performance.

  5. Developing a Natural Gas-Powered Bus Rapid Transit Service: A Case Study on Leadership: Roaring Fork Transportation Authority (Presentation); NREL (National Renewable Energy Laboratory)

    SciTech Connect

    Schroeder, A.

    2015-03-01

    The Roaring Fork Transportation Authority (RFTA) represents a series of unique successes in alternative fuel deployment by pushing the envelope with innovative solutions. In the last year, RFTA demonstrated the ability to utilize compressed natural gas buses at a range of altitudes, across long distances, in extreme weather conditions and in a modern indoor fueling and maintenance facility - allwhile saving money and providing high-quality customer service. This case study will highlight how the leadership of organizations and communities that are implementing advances in natural gas vehicle technology is paving the way for broader participation.

  6. Poor smokers, poor quitters, and cigarette tax regressivity.

    PubMed

    Remler, Dahlia K

    2004-02-01

    The traditional view that excise taxes are regressive has been challenged. I document the history of the term regressive tax, show that traditional definitions have always found cigarette taxes to be regressive, and illustrate the implications of the greater price responsiveness observed among the poor. I explain the different definitions of tax burden: accounting, welfare-based willingness to pay, and welfare-based time inconsistent. Progressivity (equity across income groups) is sensitive to the way in which tax burden is assessed. Analysis of horizontal equity (fairness within a given income group) shows that cigarette taxes heavily burden poor smokers who do not quit, no matter how tax burden is assessed.

  7. HST imaging of hydrogen-poor ejecta in Abell 30 and Abell 78 - Wind-blown cometary structures

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Harrington, J. P.; Tsvetanov, Zlatan; Clegg, Robin E. S.

    1993-01-01

    HST Faint Object Camera images of hydrogen-poor gas in the planetary nebulae A30 and A78 have revealed remarkable 'cometary' structures in the O III 5007-A forbidden line. Most of these cometary structures, consisting of compact (0.15-0.5 arcsec) knots with radial tails several arcsec in length, are located in an equatorial plane in both nebulae. In addition, two bright, compact (0.3 arcsec) polar knots are present in A30, one of them forming a bow shock. Corresponding polar features in A78 are more diffuse. The central stars of both nebulae have energetic winds which are most likely responsible for the 'cometary' knot morphology. We interpret this morphology in terms of dense (several thousand electrons per cu cm) H-poor condensations whose outer expanding layers are swept outward by stellar winds. Photoionization modeling indicates that while dense knot cores are mostly heated by atomic photoionization, expanding tenuous gas is heated by photoelectrons ejected from abundant dust grains. Our models predict steep temperature gradients for which there is observational evidence and possible abrupt phase transitions in the expanding gas.

  8. Clean air program: Design guidelines for bus transit systems using compressed natural gas as an alternative fuel. Final report, July 1995-April 1996

    SciTech Connect

    Raj, P.K.; Hathaway, W.T.; Kangas, R.

    1996-06-01

    The guidelines document presents various facility and bus design issues that need to be considered to ensure safe operations when using CNG (Compressed Natural Gas) as the alternative fuel. Fueling facility, garaging facility, maintenance facility requirements and safety practices are indicated. Among the issues discussed are fuel properties, potential hazards, fuel requirements for specified level of service, applicable codes and standards, ventilation, and electrical classification. Critical fuel related safety issues in the design of the related systems on the bus are also discussed.

  9. Generation, detection and characterization of gas-phase transition metal aggregates and compounds. Final technical report, September 15, 1991--July 14, 1994

    SciTech Connect

    Steimle, T.C.

    1994-11-12

    The goal of this research project has been to identify and characterize small gas-phase metal containing molecules and relate these properties to proposed reaction mechanisms. Of particular emphasis has been the elucidation of the mechanism for activation of C-H, N-H, S-H, and C-C bonds in CH{sub 4}, HCCH, H{sub 2}S and NH{sub 3} by platinum, titanium, molybdenum, and niobium.

  10. Coyote series data report LLNL/NWC 1981 LNG spill tests dispersion, vapor burn, and rapid-phase-transition. Volume 1. [7 experiments with liquefied natural gas, 2 with liquid methane, and one with liquid nitrogen

    SciTech Connect

    Goldwire, H.C. Jr.; Rodean, H.C.; Cederwall, R.T.; Kansa, E.J.; Koopman, R.P.; McClure, J.W.; McRae, T.G.; Morris, L.K.; Kamppinen, L.; Kiefer, R.D.

    1983-10-01

    The Coyote series of liquefied natural gas (LNG) spill experiments was performed at the Naval Weapons Center (NWC), China Lake, California, during the summer and fall of 1981. These tests were a joint effort of the Lawrence Livermore National Laboratory (LLNL) and the NWC and were sponsored by the US Department of Energy (DOE) and the Gas Research Institute. There were ten Coyote experiments, five primarily for the study of vapor dispersion and burning vapor clouds, and five for investigating the occurrence of rapid-phase-transition (RPT) explosions. Each of the last four of the five RPT tests consisted of a series of three spills. Seven experiments were with LNG, two were with liquid methane (LCH/sub 4/), and one was with liquid nitrogen (LN/sub 2/). Three arrays of instrumentation were deployed. An array of RPT diagnostic instruments was concentrated at the spill pond and was operated during all of the tests, vapor burn as well as RPT. The wind-field array was operated during the last nine experiments to define the wind direction and speed in the area upwind and downwind of the spill pond. The gas-dispersion array was deployed mostly downwind of the spill pond to measure gas concentration, humidity, temperature, ground heat flux, infrared (IR) radiation, and flame-front passage during three of the vapor dispersion and burn experiments (Coyotes 3, 5, and 6). High-speed color motion pictures were taken during every test, and IR imagery (side and overhead) was obtained during some vapor-burn experiments. Data was obtained by radiometers during Coyotes 3, 6, and 7. This report presents a comprehensive selection of the data obtained. It does not include any data analysis except that required to determine the test conditions and the reliability of the data. Data analysis is to be reported in other publications. 19 references, 76 figures, 13 tables.

  11. Discovery of the most metal-poor damped Lyman-α system

    NASA Astrophysics Data System (ADS)

    Cooke, Ryan J.; Pettini, Max; Steidel, Charles C.

    2017-01-01

    We report the discovery and analysis of the most metal-poor damped Lyman-α (DLA) system currently known, based on observations made with the Keck HIRES spectrograph. The metal paucity of this system has only permitted the determination of three element abundances: [C/H] =-3.43 ± 0.06, [O/H] =-3.05 ± 0.05, and [Si/H] =-3.21 ± 0.05, as well as an upper limit on the abundance of iron: [Fe/H] ≤-2.81. This DLA is among the most carbon-poor environment currently known with detectable metals. By comparing the abundance pattern of this DLA to detailed models of metal-free nucleosynthesis, we find that the chemistry of the gas is consistent with the yields of a 20.5 M⊙ metal-free star that ended its life as a core-collapse supernova; the abundances we measure are inconsistent with the yields of pair-instability supernovae. Such a tight constraint on the mass of the progenitor Population III star is afforded by the well-determined C/O ratio, which we show depends almost monotonically on the progenitor mass when the kinetic energy of the supernova explosion is Eexp ≳ 1.5 × 1051 erg. We find that the DLA presented here has just crossed the critical `transition discriminant' threshold, rendering the DLA gas now suitable for low mass star formation. We also discuss the chemistry of this system in the context of recent models that suggest some of the most metal-poor DLAs are the precursors of the `first galaxies', and are the antecedents of the ultra-faint dwarf galaxies.

  12. Discovery of the most metal-poor damped Lyman-α system

    NASA Astrophysics Data System (ADS)

    Cooke, Ryan J.; Pettini, Max; Steidel, Charles C.

    2017-05-01

    We report the discovery and analysis of the most metal-poor damped Lyman α (DLA) system currently known, based on observations made with the Keck HIRES spectrograph. The metal paucity of this system has only permitted the determination of three element abundances: [C/H] = -3.43 ± 0.06, [O/H] = -3.05 ± 0.05 and [Si/H] = -3.21 ± 0.05, as well as an upper limit on the abundance of iron: [Fe/H] ≤ -2.81. This DLA is among the most carbon-poor environment currently known with detectable metals. By comparing the abundance pattern of this DLA to detailed models of metal-free nucleosynthesis, we find that the chemistry of the gas is consistent with the yields of a 20.5 M⊙ metal-free star that ended its life as a core-collapse supernova; the abundances we measure are inconsistent with the yields of pair-instability supernovae. Such a tight constraint on the mass of the progenitor Population III star is afforded by the well-determined C/O ratio, which we show depends almost monotonically on the progenitor mass when the kinetic energy of the supernova explosion is Eexp ≳ 1.5 × 1051 erg. We find that the DLA presented here has just crossed the critical 'transition discriminant' threshold, rendering the DLA gas now suitable for low mass star formation. We also discuss the chemistry of this system in the context of recent models that suggest some of the most metal-poor DLAs are the precursors of the 'first galaxies', and are the antecedents of the ultrafaint dwarf galaxies.

  13. Transition Planning

    ERIC Educational Resources Information Center

    Statfeld, Jenna L.

    2011-01-01

    Post-school transition is the movement of a child with disabilities from school to activities that occur after the completion of school. This paper provides information about: (1) post-school transition; (2) transition plan; (3) transition services; (4) transition planning; (5) vocational rehabilitation services; (6) services that are available…

  14. Blue metal-poor stars

    NASA Astrophysics Data System (ADS)

    Preston, George W.; Sneden, Christopher

    2004-12-01

    We review the discovery of blue metal-poor (BMP) stars and the resolution of this population into blue stragglers and intermediate-age Main-Sequence stars by use of binary fractions. We show that the specific frequencies of blue stragglers in the halo field and in globular clusters differ by an order of magnitude. We attribute this difference to the different modes of production of these two populations. We report carbon and s-process enrichment among very metal-poor field blue stragglers and discuss how this result can be used to further resolve field blue stragglers into groups formed during RGB and AGB evolution of their erstwhile primary companions.

  15. The management of poor performance

    PubMed Central

    Mayberry, John F

    2007-01-01

    Identification of poor performance is in an integral part of government policy. The suggested approach for the identification of such problems, advocated by the General Medical Council, is that of appraisal. However, traditionally, there has been a reluctance to deal with poor performers, as all doctors have made mistakes and are usually only too ready to forgive and be non‐critical of colleagues. The problems are widespread, and 6% of the senior hospital workforce in any 5‐year period may have problems. PMID:17308213

  16. The discoveries of WASP-91b, WASP-105b and WASP-107b: Two warm Jupiters and a planet in the transition region between ice giants and gas giants

    NASA Astrophysics Data System (ADS)

    Anderson, D. R.; Collier Cameron, A.; Delrez, L.; Doyle, A. P.; Gillon, M.; Hellier, C.; Jehin, E.; Lendl, M.; Maxted, P. F. L.; Madhusudhan, N.; Pepe, F.; Pollacco, D.; Queloz, D.; Ségransan, D.; Smalley, B.; Smith, A. M. S.; Triaud, A. H. M. J.; Turner, O. D.; Udry, S.; West, R. G.

    2017-08-01

    We report the discoveries of three transiting exoplanets. WASP-91b is a warm Jupiter (1.34 MJup, 1.03 RJup) in a 2.8-day orbit around a metal-rich K3 star. WASP-105b is a warm Jupiter (1.8 MJup, 0.96 RJup) in a 7.9-day orbit around a metal-rich K2 star. WASP-107b is a warm super-Neptune/sub-Saturn (0.12 MJup, 0.94 RJup) in a 5.7-day orbit around a solar-metallicity K6 star. Considering that giant planets seem to be more common around stars of higher metallicity and stars of higher mass, it is notable that the hosts are all metal-rich, late-type stars. With orbital separations that place both WASP-105b and WASP-107b in the weak-tide regime, measurements of the alignment between the planets' orbital axes and their stars' spin axes may help us to understand the inward migration of short-period, giant planets. The mass of WASP-107b (2.2 MNep, 0.40 MSat) places it in the transition region between the ice giants and gas giants of the Solar System. Its radius of 0.94 RJup suggests that it is a low-mass gas giant with a H/He-dominated composition. The planet thus sets a lower limit of 2.2 MNep on the planetary mass above which large gaseous envelopes can be accreted and retained by proto-planets on their way to becoming gas giants. We may discover whether WASP-107b more closely resembles an ice giant or a gas giant by measuring its atmospheric metallicity via transmission spectroscopy, for which WASP-107b is a very good target. Based on observations made with: the WASP-South photometric survey instrument, the 0.6-m TRAPPIST robotic imager, and the EulerCam camera and the CORALIE spectrograph mounted on the 1.2-m Euler-Swiss telescope.The photometric time-series and radial-velocity data used in this work are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/A110

  17. Transition Planning for Foster Youth

    ERIC Educational Resources Information Center

    Geenen, Sarah J.; Powers, Laurie E.

    2006-01-01

    The study evaluated the IEPs/Individualized Transition Plans of 45 students who were in special education and foster care, and compared them to the plans of 45 students who were in special education only. Results indicate that the transition plans of foster youth with disabilities were poor in quality, both in absolute terms and in comparison to…

  18. Gas and Gas Pains

    MedlinePlus

    ... simple measures can help reduce the amount of gas you produce and relieve your discomfort and embarrassment. For most ... and vegetables to help reduce the amount of gas they produce. For Beano to be effective, you need to ...

  19. Gas and Bloating

    PubMed Central

    2006-01-01

    Gaseous symptoms including eructation, flatulence, and bloating occur as a consequence of excess gas production, altered gas transit, or abnormal perception of normal amounts of gas within the gastrointestinal tract. There are many causes of gas and bloating including aerophagia, luminal obstructive processes, carbohydrate intolerance syndromes, small intestinal bacterial overgrowth, diseases of gut motor activity, and functional bowel disorders including irritable bowel syndrome (IBS). Because of the prominence of gaseous complaints in IBS, recent investigations have focused on new insights into pathogenesis and novel therapies of bloating. The evaluation of the patient with unexplained gas and bloating relies on careful exclusion of organic disease with further characterization of the underlying condition with directed functional testing. Treatment of gaseous symptomatology should be targeted to pathophysiologic defects whenever possible. Available therapies include lifestyle alterations, dietary modifications, enzyme preparations, adsorbents and agents which reduce surface tension, treatments that alter gut flora, and drugs that modulate gut transit. PMID:28316536

  20. Reactions of methyl fluoride with atomic transition-metal and main-group cations: gas-phase room-temperature kinetics and periodicities in reactivity.

    PubMed

    Zhao, Xiang; Koyanagi, Gregory K; Bohme, Diethard K

    2006-09-14

    Reactions of CH(3)F have been surveyed systematically at room temperature with 46 different atomic cations using an inductively coupled plasma/selected-ion flow tube tandem mass spectrometer. Rate coefficients and product distributions were measured for the reactions of fourth-period atomic ions from K(+) to Se(+), of fifth-period atomic ions from Rb(+) to Te(+) (excluding Tc(+)), and of sixth-period atomic ions from Cs(+) to Bi(+). Primary reaction channels were observed corresponding to F atom transfer, CH(3)F addition, HF elimination, and H(2) elimination. The early-transition-metal cations exhibit a much more active chemistry than the late-transition-metal cations, and there are periodic features in the chemical activity and reaction efficiency that maximize with Ti(+), As(+), Y(+), Hf(+), and Pt(+). F atom transfer appears to be thermodynamically controlled, although a periodic variation in efficiency is observed within the early-transition-metal cations which maximizes with Ti(+), Y(+), and Hf(+). Addition of CH(3)F was observed exclusively (>99%) with the late-fourth-period cations from Mn(+) to Ga(+), the fifth-period cations from Ru(+) to Te(+), and the sixth-period cations from Hg(+) to Bi(+) as well as Re(+). Periodic trends are observed in the effective bimolecular rate coefficient for CH(3)F addition, and these are consistent with expected trends in the electrostatic binding energies of the adduct ions and measured trends in the standard free energy of addition. HF elimination is the major reaction channel with As(+), while dehydrogenation dominates the reactions of W(+), Os(+), Ir(+), and Pt(+). Sequential F atom transfer is observed with the early-transition-metal cations, with the number of F atoms transferred increasing across the periodic table from two to four, maximizing at four for the group 5 cations Nb(+)(d(4)) and Ta(+)(d(3)s(1)), and stopping at two with V(+)(d(4)). Sequential CH(3)F addition was observed with many atomic cations and all of

  1. NGC 1252: a high altitude, metal poor open cluster remnant

    NASA Astrophysics Data System (ADS)

    de la Fuente Marcos, R.; de la Fuente Marcos, C.; Moni Bidin, C.; Carraro, G.; Costa, E.

    2013-09-01

    If stars form in clusters but most stars belong to the field, understanding the details of the transition from the former to the latter is imperative to explain the observational properties of the field. Aging open clusters are one of the sources of field stars. The disruption rate of open clusters slows down with age but, as an object gets older, the distinction between the remaining cluster or open cluster remnant (OCR) and the surrounding field becomes less and less obvious. As a result, finding good OCR candidates or confirming the OCR nature of some of the best candidates still remain elusive. One of these objects is NGC 1252, a scattered group of about 20 stars in Horologium. Here we use new wide-field photometry in the UBVI passbands, proper motions from the Yale/San Juan SPM 4.0 catalogue and high-resolution spectroscopy concurrently with results from N-body simulations to decipher NGC 1252's enigmatic character. Spectroscopy shows that most of the brightest stars in the studied area are chemically, kinematically and spatially unrelated to each other. However, after analysing proper motions, we find one relevant kinematic group. This sparse object is relatively close (˜1 kpc), metal poor and is probably not only one of the oldest clusters (3 Gyr) within 1.5 kpc from the Sun but also one of the clusters located farthest from the disc, at an altitude of nearly -900 pc. That makes NGC 1252 the first open cluster that can be truly considered a high Galactic altitude OCR: an unusual object that may hint at a star formation event induced on a high Galactic altitude gas cloud. We also conclude that the variable TW Horologii and the blue straggler candidate HD 20286 are unlikely to be part of NGC 1252. NGC 1252 17 is identified as an unrelated, Population II cannonball star moving at about 400 km s-1.

  2. Variational transition state theory

    SciTech Connect

    Truhlar, D.G.

    1993-12-01

    This research program involves the development of variational transition state theory (VTST) and semiclassical tunneling methods for the calculation of gas-phase reaction rates and selected applications. The applications are selected for their fundamental interest and/or their relevance to combustion.

  3. Standard and Poor's Rich Website

    ERIC Educational Resources Information Center

    DiMaria, Frank

    2006-01-01

    To help parents investigate and locate quality school districts and to help policy-makers, principals, and superintendents to make well-informed decisions about education, Standard and Poor's has launched a website called SchoolMatters.com. It is recognized by the U.S. Department of Education and featured on its website (www.ed.gov/parents).…

  4. Prospects for the Working Poor

    ERIC Educational Resources Information Center

    Miller, S. M.

    1970-01-01

    Based on a chapter entitled "Barriers to Employment of the Disadvantaged by Martin Deutsch and S. M. Miller in "Manpower Report of the President, 1968. Discusses the Nixon proposals for remediating poverty in relation to the socioeconomic factors operating to maintain the condition of being poor while working. (JM)

  5. The Power of Poor Communications

    ERIC Educational Resources Information Center

    Schaub, Alfred R.

    1975-01-01

    Most breakdowns in communications are the result of the quest for power on behalf of organization members, not the result of poor communications training. Organizational power may be accrued by withholding information, sabotaging communications, refusing to communicate bad news to superiors, and avoiding confrontations by not communicating at all.…

  6. Prospects for the Working Poor

    ERIC Educational Resources Information Center

    Miller, S. M.

    1970-01-01

    Based on a chapter entitled "Barriers to Employment of the Disadvantaged by Martin Deutsch and S. M. Miller in "Manpower Report of the President, 1968. Discusses the Nixon proposals for remediating poverty in relation to the socioeconomic factors operating to maintain the condition of being poor while working. (JM)

  7. Educating Canada's Urban Poor Children.

    ERIC Educational Resources Information Center

    Maynes, Bill; Foster, Rosemary

    2000-01-01

    Presents six critical thoughts and questions about educating poor urban children in Canada. These thoughts were derived from the development of a directory of Canadian educational poverty programs. Findings from that study emphasize the increasing diversity of the student population, the importance of temporary and large-scale funding, and the…

  8. Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy

    PubMed Central

    Zhong, Jin-Rong; Zeng, Xin-Yang; Zhou, Feng-He; Ran, Qi-Dong; Sun, Chang-Yu; Zhong, Rui-Qin; Yang, Lan-Ying; Chen, Guang-Jin; Koh, Carolyn A.

    2016-01-01

    The hydrate structure type and dissociation behavior for pure methane and methane-ethane hydrates at temperatures below the ice point and atmospheric pressure were investigated using in situ Raman spectroscopic analysis. The self-preservation effect of sI methane hydrate is significant at lower temperatures (268.15 to 270.15 K), as determined by the stable C-H region Raman peaks and AL/AS value (Ratio of total peak area corresponding to occupancies of guest molecules in large cavities to small cavities) being around 3.0. However, it was reduced at higher temperatures (271.15 K and 272.15 K), as shown from the dramatic change in Raman spectra and fluctuations in AL/AS values. The self-preservation effect for methane-ethane double hydrate is observed at temperatures lower than 271.15 K. The structure transition from sI to sII occurred during the methane-ethane hydrate decomposition process, which was clearly identified by the shift in peak positions and the change in relative peak intensities at temperatures from 269.15 K to 271.15 K. Further investigation shows that the selectivity for self-preservation of methane over ethane leads to the structure transition; this kind of selectivity increases with decreasing temperature. This work provides new insight into the kinetic behavior of hydrate dissociation below the ice point. PMID:27941857

  9. Itinerant magnetic phases and quantum Lifshitz transitions in a three-dimensional repulsively interacting Fermi gas with spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Zhang, Shang-Shun; Ye, Jinwu; Liu, Wu-Ming

    2016-09-01

    Magnetic phenomena in itinerant electron systems have been at the forefront of materials science. Here we show that the Weyl spin-orbit coupling (SOC) in three-dimensional repulsively interacting itinerant Fermi systems opens up a platform to host new itinerant magnetic phases, excitations, and phase transitions. A putative ferromagnetic state (FM) is always unstable against a stripe spiral spin density wave (S-SDW) or a stripe longitudinal SDW (LSDW) at small or large SOC strengths, respectively. The stripe-ordering wave vector is given by the nesting momentum of the two SOC-split Fermi surfaces with the same or opposite helicities at small or large SOC strengths, respectively. The LSDW is accompanied by a charge density wave (CDW) with half of its pitch. The transition from the paramagnet to the SSDW or LSDW+CDW is described by quantum Lifshitz-type actions, in sharp contrast to the Hertz-Millis types for itinerant electron systems without SOC. The collective excitations and Fermi surface reconstructions inside the SSDW and LSDW+CDW are also studied. The effects of a harmonic trap in cold-atom experiments are briefly discussed. In view of recent ground-breaking experimental advances in generating two-dimensional SOC in cold atoms, these phenomena can be observed in current or near-future cold-atom experiments even at very weak interactions. They may also be relevant to some itinerant magnetic materials with a strong SOC.

  10. Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhong, Jin-Rong; Zeng, Xin-Yang; Zhou, Feng-He; Ran, Qi-Dong; Sun, Chang-Yu; Zhong, Rui-Qin; Yang, Lan-Ying; Chen, Guang-Jin; Koh, Carolyn A.

    2016-12-01

    The hydrate structure type and dissociation behavior for pure methane and methane-ethane hydrates at temperatures below the ice point and atmospheric pressure were investigated using in situ Raman spectroscopic analysis. The self-preservation effect of sI methane hydrate is significant at lower temperatures (268.15 to 270.15 K), as determined by the stable C-H region Raman peaks and AL/AS value (Ratio of total peak area corresponding to occupancies of guest molecules in large cavities to small cavities) being around 3.0. However, it was reduced at higher temperatures (271.15 K and 272.15 K), as shown from the dramatic change in Raman spectra and fluctuations in AL/AS values. The self-preservation effect for methane-ethane double hydrate is observed at temperatures lower than 271.15 K. The structure transition from sI to sII occurred during the methane-ethane hydrate decomposition process, which was clearly identified by the shift in peak positions and the change in relative peak intensities at temperatures from 269.15 K to 271.15 K. Further investigation shows that the selectivity for self-preservation of methane over ethane leads to the structure transition; this kind of selectivity increases with decreasing temperature. This work provides new insight into the kinetic behavior of hydrate dissociation below the ice point.

  11. Gas-phase energy of the S2←S0 transition and electrostatic properties of the S2 state of carotenoid peridinin via a solvatochromic shift and orientation broadening of the absorption spectrum.

    PubMed

    Pavlovich, Vladimir S

    2014-10-01

    The solvent effect on the position and the shape of the absorption spectrum of peridinin for 12 protic and aprotic solvents as well as the temperature effect for methanol were studied using a solvatochromic theory based on the Onsager sphere cavity model. (Experimental data have been provided by T. Polivka and V. Sundström.) Solvatochromic calculations combined with estimations of orientation broadening of the absorption spectrum by convolution allowed the conclusion that the orientation (dipole-dipole), induction and dispersion solute-solvent interactions reasonably describes the position of the 0-0 frequency. The orientation interactions led to the blue solvatochromic shift, separating them from the induced and dispersion interactions, which produce a red shift. The FWHM of Gaussian of inhomogeneous broadening originated from the fluctuations of orientation interactions was demonstrated to be high (945 cm(-1)) even for such a nonpolar solvent as hexane. The value of |Δμ|/cos φ of -18.7 D has been found (Δμ = μ2 - μg, φ is the angle between Δμ and μg). By assigning peridinin to the idealized C2v point group, the large change of dipole moment |Δμ| of 18.7 D under S2←S0 transition is obtained for peridinin in gas phase. Moreover, the S2-excited state dipole moment μ2 has the opposite orientation relative to that at the ground S0 state μg. The determined gas-phase 0-0 energy of the S2←S0 transition, 22 910 cm(-1) (2.84 eV) is employed to calculate the polarizability change between the S0 and S2 states of 376 Å(3). The finding for the effective Onsager radius is of 9.4 Å. Obtained results for electrostatic properties of the S2 state are compared with those known from Stark spectroscopy and quantum-mechanical calculations.

  12. Are poor Chinese text comprehenders also poor in written composition?

    PubMed

    Guan, Connie Qun; Ye, Feifei; Meng, Wanjin; Leong, Che Kan

    2013-10-01

    We studied the performance in three genres of Chinese written composition (narration, exposition, and argumentation) of 158 grade 4, 5, and 6 poor Chinese text comprehenders compared with 156 good Chinese text comprehenders. We examined text comprehension and written composition relationship. Verbal working memory (verbal span working memory and operation span working memory) and different levels of linguistic tasks-morphological sensitivity (morphological compounding and morphological chain), sentence processing (syntax construction and syntax integrity), and text comprehension (narrative and expository texts)-were used to predict separately narrative, expository, and argumentation written compositions in these students. Grade for grade, the good text comprehenders outperformed the poor text comprehenders in all tasks, except for morphological chain. Hierarchical multiple regression analyses showed differential contribution of the tasks to different genres of writing. In particular, text comprehension made unique contribution to argumentation writing in the poor text comprehenders. Future studies should ask students to read and write parallel passages in the same genre for better comparison and incorporate both instructional and motivational variables.

  13. TRANSITION REGION EMISSION FROM SOLAR FLARES DURING THE IMPULSIVE PHASE

    SciTech Connect

    Johnson, H.; Raymond, J. C.; Murphy, N. A.; Suleiman, R.; Giordano, S.; Ko, Y.-K.; Ciaravella, A.

    2011-07-10

    There are relatively few observations of UV emission during the impulsive phases of solar flares, so the nature of that emission is poorly known. Photons produced by solar flares can resonantly scatter off atoms and ions in the corona. Based on off-limb measurements by the Solar and Heliospheric Observatory/Ultraviolet Coronagraph Spectrometer, we derive the O VI {lambda}1032 luminosities for 29 flares during the impulsive phase and the Ly{alpha} luminosities of 5 flares, and we compare them with X-ray luminosities from GOES measurements. The upper transition region and lower transition region luminosities of the events observed are comparable. They are also comparable to the luminosity of the X-ray emitting gas at the beginning of the flare, but after 10-15 minutes the X-ray luminosity usually dominates. In some cases, we can use Doppler dimming to estimate flow speeds of the O VI emitting gas, and five events show speeds in the 40-80 km s{sup -1} range. The O VI emission could originate in gas evaporating to fill the X-ray flare loops, in heated chromospheric gas at the footpoints, or in heated prominence material in the coronal mass ejection. All three sources may contribute in different events or even in a single event, and the relative timing of UV and X-ray brightness peaks, the flow speeds, and the total O VI luminosity favor each source in one or more events.

  14. Constraining the volatile fraction of planets from transit observations

    NASA Astrophysics Data System (ADS)

    Alibert, Y.

    2016-06-01

    Context. The determination of the abundance of volatiles in extrasolar planets is very important as it can provide constraints on transport in protoplanetary disks and on the formation location of planets. However, constraining the internal structure of low-mass planets from transit measurements is known to be a degenerate problem. Aims: Using planetary structure and evolution models, we show how observations of transiting planets can be used to constrain their internal composition, in particular the amount of volatiles in the planetary interior, and consequently the amount of gas (defined in this paper to be only H and He) that the planet harbors. We first explore planets that are located close enough to their star to have lost their gas envelope. We then concentrate on planets at larger distances and show that the observation of transiting planets at different evolutionary ages can provide statistical information on their internal composition, in particular on their volatile fraction. Methods: We computed the evolution of low-mass planets (super-Earths to Neptune-like) for different fractions of volatiles and gas. We used a four-layer model (core, silicate mantle, icy mantle, and gas envelope) and computed the internal structure of planets for different luminosities. With this internal structure model, we computed the internal and gravitational energy of planets, which was then used to derive the time evolution of the planet. Since the total energy of a planet depends on its heat capacity and density distribution and therefore on its composition, planets with different ice fractions have different evolution tracks. Results: We show for low-mass gas-poor planets that are located close to their central star that assuming evaporation has efficiently removed the entire gas envelope, it is possible to constrain the volatile fraction of close-in transiting planets. We illustrate this method on the example of 55 Cnc e and show that under the assumption of the absence of

  15. Rare-gas clusters in intense VUV, XUV and soft x-ray pulses: signatures of the transition from nanoplasma-driven cluster expansion to Coulomb explosion in ion and electron spectra

    NASA Astrophysics Data System (ADS)

    Arbeiter, Mathias; Fennel, Thomas

    2011-05-01

    We investigate the wavelength-dependent ionization, heating, and expansion dynamics of medium-sized rare-gas clusters (Ar923) under intense femtosecond short-wavelength free-electron laser pulses by quasi-classical molecular dynamics simulations. A comparison of the interaction dynamics for pulses with planckω=20, 38 and 90 eV photon energy at fixed total excitation energy indicates a smooth transition from plasma-driven cluster expansion, where predominantly surface ions are expelled by hydrodynamic forces, to quasi-electrostatic behavior with almost pure Coulomb explosion. Corresponding signatures in the time-dependent cluster dynamics, as well as in the final ion and electron spectra, corroborate that this transition is linked to a crossover in the electron emission processes. The resulting signatures in the electron spectra are shown to be even more reliable for identifying the cluster expansion mechanisms than ion energy spectra. It is shown that the prevailing ionization mechanism and the dominant expansion process can be roughly estimated by a simple frustration parameter.

  16. Computer simulation of supersonic rarefied gas flow in the transition region, about a spherical probe; a Monte Carlo approach with application to rocket-borne ion probe experiments

    NASA Technical Reports Server (NTRS)

    Horton, B. E.; Bowhill, S. A.

    1971-01-01

    This report describes a Monte Carlo simulation of transition flow around a sphere. Conditions for the simulation correspond to neutral monatomic molecules at two altitudes (70 and 75 km) in the D region of the ionosphere. Results are presented in the form of density contours, velocity vector plots and density, velocity and temperature profiles for the two altitudes. Contours and density profiles are related to independent Monte Carlo and experimental studies, and drag coefficients are calculated and compared with available experimental data. The small computer used is a PDP-15 with 16 K of core, and a typical run for 75 km requires five iterations, each taking five hours. The results are recorded on DECTAPE to be printed when required, and the program provides error estimates for any flow field parameter.

  17. Health solutions for the poor.

    PubMed

    Castro, J L; Fujiwara, P I; Bhambal, P; Emaille-Léotard, N; Harries, A D

    2014-03-21

    The International Union Against Tuberculosis and Lung Disease (The Union) is the oldest international non-governmental organisation involved in the fight against tuberculosis. In 2008, the Institute of The Union was challenged to think boldly about the future and to develop a diverse work portfolio covering a wide spectrum of lung health and other disease-related problems. The vision adopted by The Union at that time was 'Health solutions for the poor'. More recently, there has been lengthy debate about the need for the Union to concentrate just on its core mandate of tuberculosis and lung health and for the Union's vision to reflect this narrower spectrum of activity as 'Lung health solutions for the poor'. In this viewpoint article we outline our reasons for believing that this narrower vision is incompatible with The Union's mission statement, and we argue that making such a change would be a mistake.

  18. Characterizing the intrinsic stability of gas-phase clusters of transition metal complex dianions with alkali metal counterions: counterion perturbation of multiply charged anions.

    PubMed

    Burke, Ruth M; Boxford, William E; Dessent, Caroline E H

    2007-02-14

    The authors report the gas-phase generation and characterization of a series of cation-dianion clusters, e.g., M(+).PtCl(6) (2-), M(+).PtCl(4) (2-), M(+).Pt(CN)(6) (2-), and M(+).Pd(CN)(4) (2-), where M(+)=Na(+),K(+),Rb(+), as model systems for investigating gas-phase contact ionpairs. Low-energy collisional excitation of these systems isolated within a quadrupole ion trap reveals that the fragmentation products are determined by the dianion and are independent of the counterion. This indicates that cation-dianion clusters represent gaseous ion-pair complexes, in line with recent findings for K(+).Pt(CN)(n) (2-), n=4,6 [Burke et al., J. Chem. Phys. 125, 021105 (2006)]. The relative fragmentation energies of several cation-dianion systems are obtained as a function of the counterion to explore the nature of ion-pair binding. For most of the systems studied, e.g., M(+).PtCl(6) (2-), the fragmentation energy increases as the cation size decreases, in line with a simple electrostatic description of the cation-dianion binding. However, the M(+).Pt(CN)(4) (2-) clusters displayed the reverse trend with the fragmentation energy increasing as the cation size increases. Density functional theory calculations of the cation-dianion fragmentation potential energy surfaces reveal the existence of a novel double-minima surface, separated by a repulsive Coulomb barrierlike feature at short range. The experimentally observed trends in the fragmentation energies can be fully understood with reference to the computed surfaces, hence providing strong support for the existence of the double-minima surface.

  19. Inverse gas chromatography study on the effect of humidity on the mass transport of alcohols in an ethylene-vinyl alcohol copolymer near the glass transition temperature.

    PubMed

    Cava, David; Lagarón, José M; Martínez-Giménez, Félix; Gavara, Rafael

    2007-12-21

    Inverse gas chromatography (IGC) was used to study the effect of moisture on transport properties of three low molecular weight alcohols (methanol, ethanol, and 1-butanol) through high barrier copolymers of ethylene-vinyl alcohol with an ethylene content of 38%mol (EVOH38) at 40 degrees C. The value of the partition coefficient (K) was obtained by using two approaches: (a) the fit of the slope of sorption isotherms obtained through the method of Kiselev and Yashin; and (b) the solution to the model of Romdhane and Danner obtained by using the law of moments. The second method also allowed the estimation of the diffusion coefficient (D(p)) at the different humidity conditions. None of these two methods were applicable at low values of relative humidity. With the first method, the diffusion of the permeants through the copolymer was not fast enough to allow them to reach the core of the EVOH particles used as stationary phase resulting in sorption values unrealistically low. The fit of the chromatograms obtained by using the second method also suggested questionable values of the mass transport parameters. Although the theoretical curve perfectly described the chromatogram, the low extent of the interaction and the slow diffusion resulted in interdependent values of the coefficients K and D(p), with infinite pairs of values providing the same curve profile. As the relative humidity of the carrier gas increased, the diffusivity and the sorption of the alcohols also increased, making both methods applicable. In the case of the partition coefficient, the sorption of the biggest molecules (ethanol and 1-butanol) was the most affected, the increment of K for methanol being moderate. As regards the D(p) value, methanol was the most influenced compound and 1-butanol the least. Finally, a sharp increment of the D(p) of the three alcohols was observed between 35 and 47% RH and attributed to the plasticization of the copolymer.

  20. Modeling the transition region

    NASA Astrophysics Data System (ADS)

    Singer, Bart A.

    1994-04-01

    The calculation of engineering flows undergoing laminar-turbulent transition presents special problems. Mean-flow quantities obey neither the fully laminar nor the fully turbulent correlations. In addition, local maxima in skin friction, wall temperature, and heat transfer often occur near the end of the transition region. Traditionally, modeling this region has been important for the design of turbine blades, where the transition region is long in relation to the chord length of the blade. More recently, the need for better transition-region models has been recognized by designers of hypersonic vehicles where the high Mach number, the low Reynolds number, and the low-disturbance flight environment emphasize the importance of the transition region. Needless to say, a model that might work well for the transitional flows typically found in gas turbines will not necessarily work well for the external surface of a hypersonic vehicle. In Section 2 of this report, some of the important flow features that control the transition region will be discussed. In Section 3, different approaches to the modeling problem will be summarized and cataloged. Fully turbulent flow models will be discussed in detail in Section 4; models specifically designed for transitional flow, in Section 5; and the evaluation of models, in Section 6.

  1. Individual and community factors associated with geographic clusters of poor HIV care retention and poor viral suppression

    PubMed Central

    Eberhart, Michael G.; Yehia, Baligh R.; Hillier, Amy; Voytek, Chelsea D.; Fiore, Danielle J.; Blank, Michael; Frank, Ian; Metzger, David S.; Brady, Kathleen A.

    2015-01-01

    Background Previous analyses identified specific geographic areas in Philadelphia (hotspots) associated with negative outcomes along the HIV care continuum. We examined individual and community factors associated with residing in these hotspots. Methods Retrospective cohort of 1,404 persons newly diagnosed with HIV in 2008–2009 followed for 24 months after linkage to care. Multivariable regression examined associations between individual (age, sex, race/ethnicity, HIV transmission risk, and insurance status) and community (economic deprivation, distance to care, access to public transit, and access to pharmacy services) factors and the outcomes: residence in a hotspot associated with poor retention in care and residence in a hotspot associated with poor viral suppression. Results 24.4% and 13.7% of persons resided in hotspots associated with poor retention and poor viral suppression, respectively. For persons residing in poor retention hotspots, 28.3% were retained in care compared to 40.4% of those residing outside hotspots (p<0.05). Similarly, for persons residing in poor viral suppression hotspots, 51.4% achieved viral suppression compared to 75.3% of those outside hotspots (p<.0.05). Factors significantly associated with residence in a poor retention hotspots included: female sex, lower economic deprivation, greater access to public transit, shorter distance to medical care, and longer distance to pharmacies. Factors significantly associated with residence in a poor viral suppression hotspots included; female sex, higher economic deprivation, and shorter distance to pharmacies. Conclusions Individual and community-level associations with geographic hotspots may inform both content and delivery strategies for interventions designed to improve retention in care and viral suppression. PMID:25867777

  2. Carbon monoxide in an extremely metal-poor galaxy.

    PubMed

    Shi, Yong; Wang, Junzhi; Zhang, Zhi-Yu; Gao, Yu; Hao, Cai-Na; Xia, Xiao-Yang; Gu, Qiusheng

    2016-12-09

    Extremely metal-poor galaxies with metallicity below 10% of the solar value in the local universe are the best analogues to investigating the interstellar medium at a quasi-primitive environment in the early universe. In spite of the ongoing formation of stars in these galaxies, the presence of molecular gas (which is known to provide the material reservoir for star formation in galaxies such as our Milky Way) remains unclear. Here we report the detection of carbon monoxide (CO), the primary tracer of molecular gas, in a galaxy with 7% solar metallicity, with additional detections in two galaxies at higher metallicities. Such detections offer direct evidence for the existence of molecular gas in these galaxies that contain few metals. Using archived infrared data, it is shown that the molecular gas mass per CO luminosity at extremely low metallicity is approximately one-thousand times the Milky Way value.

  3. Carbon monoxide in an extremely metal-poor galaxy

    PubMed Central

    Shi, Yong; Wang, Junzhi; Zhang, Zhi-Yu; Gao, Yu; Hao, Cai-Na; Xia, Xiao-Yang; Gu, Qiusheng

    2016-01-01

    Extremely metal-poor galaxies with metallicity below 10% of the solar value in the local universe are the best analogues to investigating the interstellar medium at a quasi-primitive environment in the early universe. In spite of the ongoing formation of stars in these galaxies, the presence of molecular gas (which is known to provide the material reservoir for star formation in galaxies such as our Milky Way) remains unclear. Here we report the detection of carbon monoxide (CO), the primary tracer of molecular gas, in a galaxy with 7% solar metallicity, with additional detections in two galaxies at higher metallicities. Such detections offer direct evidence for the existence of molecular gas in these galaxies that contain few metals. Using archived infrared data, it is shown that the molecular gas mass per CO luminosity at extremely low metallicity is approximately one-thousand times the Milky Way value. PMID:27934880

  4. Mechanistic differences between electrochemical and gas-phase thermal oxidation of platinum-group transition metals as discerned by surface-enhanced Raman spectroscopy

    SciTech Connect

    Chan, H.Y.H.; Zou, S.; Weaver, M.J.

    1999-12-16

    electrochemical reactions at the applied potentials where surface oxidation for the latter processes proceeds at room temperature. The electrostatic driving forces for oxygen incorporation into the metal lattice (via high-field ion transport) are also typically more favorable for the gaseous systems, as evidenced by a comparison of the metal-solution and metal-gas surface potentials. The intrinsically more facile electrochemical processes thereby deduced are attributed to the occurrence of direct oxide production via a metal-oxygen place-exchange mechanism, expedited by interfacial solvation and therefore being energetically unfavorable in the anhydrous gas-phase environment. Other factors, such as the formation of precursor chemisorbed oxygen, are also considered.

  5. Effect of gas-liquid-crystal transitions in oxygen clusters on electric and magnetic activity of localized states in In2O3-SrO ceramic

    NASA Astrophysics Data System (ADS)

    Okunev, V. D.; Szymczak, R.; Szymczak, H.; Aleshkevych, P.; Glot, A. B.; Bondarchuk, A. N.

    2015-10-01

    It has been shown that the overlap of tails of the density of states of the valence and conduction bands leads to the formation of a "negative" gap in the In2O3-SrO ceramic with disordered structure and oxygen clusters in nanovoids. Two types of magnetism are observed. One of them caused by the formation of (dangling bond + O- 2 center) complexes has been found in samples saturated with oxygen. The other is associated with the presence of dangling bonds in oxygen-depleted samples. At T < 90.18 K, when oxygen molecules fall from the walls of nanovoids, small liquid oxygen droplets are formed with the release of a large number of free dangling bonds resulting in the variation of magnetization and electrical conductivity of samples. The effects caused by magnetic phase transitions in clusters of crystal oxygen are manifested at T < 54.8 K. The variations of the resistance of samples in the interval T = 5-300 K correspond to Mott's law under the dependence of the local activation energy for electron hopping on the state of oxygen clusters.

  6. An insight into the interaction of L-proline with the transition metal cations Fe(2+), Co(2+), Ni(2+): a gas phase theoretical study.

    PubMed

    Khalili, Behzad

    2016-01-01

    The interaction of Fe(2+), Co(2+), and Ni(2+) with L-proline has been studied. Three modes of interaction have been considered: salt bridged (SB), involving binding in a bi-dentate manner through the carboxylate group of L-proline, charge solvated 1 (CS1) involving carbonyl and hydroxyl oxygen, and charge solvated 2 (CS2) involving carbonyl oxygen and the lone pair of the nitrogen atom. All calculations including geometry optimization, metal ion affinities (MIAs), and frequency calculations of the binding structures of Fe(2+), Co(2+), and Ni(2+) to L-proline were calculated using the hybrid density functional theory (DFT-B3LYP) method. All three cations were found to bind preferentially in a zwitterionic (SB) coordination pattern with the metal ion affinity in the order Ni(2+) ˃ Co(2+) ˃ Fe(2+) in all binding forms. The nature of the binding interaction between metal cations and L-proline was found to be mainly electrostatic. Comparison of the infrared vibrations of the C=O, the N-H and the O-H groups of free L-proline with L-proline-M(2+) in both CS1 and CS2 complex structures indicated a considerable shift to lower frequency during complexation. In order to gain more insight into the nature of the interaction of L-proline with group VIIIB metal ions, comparison of the interaction of L-proline with other cations such as (Li(+), Na(+), K(+), Be(2+), Mg(2+), and Ca(2+)) was made. Graphical Abstract L-proline with the transition metal cations Fe(2+), Co(2+), Ni(2.)

  7. Livestock services and the poor.

    PubMed

    Ahuja, V; Redmond, E

    2004-04-01

    This paper reviews the economic framework for the delivery of livestock services to the poor. It is argued that the demand for livestock products is likely to increase rapidly and the ability of the poor to participate in the opportunities presented by this growth is linked critically to the availability of good service support, both on the input and output side. Governments therefore have a responsibility to supply the necessary public goods (including the institutions and legal frameworks), and the market infrastructure for facilitating the emergence of efficient markets for livestock services. The paper further argues that the dynamics of public policy in developing countries are much more complex than the simple application of economic logic. It is the larger political economy that often dictates policy choices. It is therefore important to integrate political economy and governance issues into the economic debate on livestock service delivery. The paper also reviews the context in which the markets for livestock services will need to function. Different countries are facing very different sets of issues, and the identification of possible interventions in livestock service markets would require careful field research and analysis. In this context, the paper suggests the elements of a research agenda for the next few years.

  8. MOLECULAR GAS IN YOUNG DEBRIS DISKS

    SciTech Connect

    Moor, A.; Abraham, P.; Kiss, Cs.; Juhasz, A.; Kospal, A.; Pascucci, I.; Apai, D.; Henning, Th.; Csengeri, T.; Grady, C.

    2011-10-10

    Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. Interestingly, the debris disk around the young main-sequence star 49 Ceti possesses a substantial amount of molecular gas and possibly represents the missing link between the two phases. Motivated to understand the evolution of the gas component in circumstellar disks via finding more 49 Ceti-like systems, we carried out a CO J = 3-2 survey with the Atacama Pathfinder EXperiment, targeting 20 infrared-luminous debris disks. These systems fill the gap between primordial and old tenuous debris disks in terms of fractional luminosity. Here we report on the discovery of a second 49 Ceti-like disk around the 30 Myr old A3-type star HD21997, a member of the Columba Association. This system was also detected in the CO(2-1) transition, and the reliable age determination makes it an even clearer example of an old gas-bearing disk than 49 Ceti. While the fractional luminosities of HD21997 and 49 Ceti are not particularly high, these objects seem to harbor the most extended disks within our sample. The double-peaked profiles of HD21997 were reproduced by a Keplerian disk model combined with the LIME radiative transfer code. Based on their similarities, 49 Ceti and HD21997 may be the first representatives of a so far undefined new class of relatively old ({approx}>8 Myr), gaseous dust disks. From our results, neither primordial origin nor steady secondary production from icy planetesimals can unequivocally explain the presence of CO gas in the disk of HD21997.

  9. Molecular Gas in Young Debris Disks

    NASA Technical Reports Server (NTRS)

    Moor, A.; Abraham, P.; Juhasz, A.; Kiss, Cs.; Pascucci, I.; Kospal, A.; Apai, D.; Henning, T.; Csengeri, T.; Grady, C.

    2011-01-01

    Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. Interestingly, the debris disk around the young main-sequence star 49 Ceti possesses a substantial amount of molecular gas and possibly represents the missing link between the two phases. Motivated to understand the evolution of the gas component in circumstellar disks via finding more 49 Ceti-like systems, we carried out a CO J = 3-2 survey with the Atacama Pathfinder EXperiment, targeting 20 infrared-luminous debris disks. These systems fill the gap between primordial and old tenuous debris disks in terms of fractional luminosity. Here we report on the discovery of a second 49 Ceti-like disk around the 30 Myr old A3-type star HD21997, a member of the Columba Association. This system was also detected in the CO(2-1) transition, and the reliable age determination makes it an even clearer example of an old gas-bearing disk than 49 Ceti. While the fractional luminosities of HD21997 and 49 Ceti are not particularly high, these objects seem to harbor the most extended disks within our sample. The double-peaked profiles of HD21997 were reproduced by a Keplerian disk model combined with the LIME radiative transfer code. Based on their similarities, 49 Ceti and HD21997 may be the first representatives of a so far undefined new class of relatively old > or approx.8 Myr), gaseous dust disks. From our results, neither primordia1 origin nor steady secondary production from icy planetesima1s can unequivocally explain the presence of CO gas in the disk ofHD21997.

  10. Molecular Gas in Young Debris Disks

    NASA Technical Reports Server (NTRS)

    Moor, A.; Abraham, P.; Juhasz, A.; Kiss, Cs.; Pascucci, I.; Kospal, A.; Apai, D.; Henning, T.; Csengeri, T.; Grady, C.

    2011-01-01

    Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. Interestingly, the debris disk around the young main-sequence star 49 Ceti possesses a substantial amount of molecular gas and possibly represents the missing link between the two phases. Motivated to understand the evolution of the gas component in circumstellar disks via finding more 49 Ceti-like systems, we carried out a CO J = 3-2 survey with the Atacama Pathfinder EXperiment, targeting 20 infrared-luminous debris disks. These systems fill the gap between primordial and old tenuous debris disks in terms of fractional luminosity. Here we report on the discovery of a second 49 Ceti-like disk around the 30 Myr old A3-type star HD21997, a member of the Columba Association. This system was also detected in the CO(2-1) transition, and the reliable age determination makes it an even clearer example of an old gas-bearing disk than 49 Ceti. While the fractional luminosities of HD21997 and 49 Ceti are not particularly high, these objects seem to harbor the most extended disks within our sample. The double-peaked profiles of HD21997 were reproduced by a Keplerian disk model combined with the LIME radiative transfer code. Based on their similarities, 49 Ceti and HD21997 may be the first representatives of a so far undefined new class of relatively old > or approx.8 Myr), gaseous dust disks. From our results, neither primordia1 origin nor steady secondary production from icy planetesima1s can unequivocally explain the presence of CO gas in the disk ofHD21997.

  11. On transit time instability in liquid jets

    NASA Technical Reports Server (NTRS)

    Grabitz, G.; Meier, G.

    1982-01-01

    A basic transit time instability in flows with disturbances of speed is found. It was shown that the mass distribution is established by and large by the described transit time effects. These transit time effects may also be involved for gas jets.

  12. Uncertainty in particle number modal analysis during transient operation of compressed natural gas, diesel, and trap-equipped diesel transit buses.

    PubMed

    Holmén, Britt A; Qu, Yingge

    2004-04-15

    The relationships between transient vehicle operation and ultrafine particle emissions are not well-known, especially for low-emission alternative bus technologies such as compressed natural gas (CNG) and diesel buses equipped with particulate filters/traps (TRAP). In this study, real-time particle number concentrations measured on a nominal 5 s average basis using an electrical low pressure impactor (ELPI) for these two bus technologies are compared to that of a baseline catalyst-equipped diesel bus operated on ultralow sulfur fuel (BASE) using dynamometer testing. Particle emissions were consistently 2 orders of magnitude lower for the CNG and TRAP compared to BASE on all driving cycles. Time-resolved total particle numbers were examined in terms of sampling factors identified as affecting the ability of ELPI to quantify the particulate matter number emissions for low-emitting vehicles such as CNG and TRAP as a function of vehicle driving mode. Key factors were instrument sensitivity and dilution ratio, alignment of particle and vehicle operating data, sampling train background particles, and cycle-to-cycle variability due to vehicle, engine, after-treatment, or driver behavior. In-cycle variability on the central business district (CBD) cycle was highest for the TRAP configuration, but this could not be attributed to the ELPI sensitivity issues observed for TRAP-IDLE measurements. Elevated TRAP emissions coincided with low exhaust temperature, suggesting on-road real-world particulate filter performance can be evaluated by monitoring exhaust temperature. Nonunique particle emission maps indicate that measures other than vehicle speed and acceleration are necessary to model disaggregated real-time particle emissions. Further testing on a wide variety of test cycles is needed to evaluate the relative importance of the time history of vehicle operation and the hysteresis of the sampling train/dilution tunnel on ultrafine particle emissions. Future studies should

  13. Sweet gas

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    When poisonous hydrogen sulfide contaminates a natural gas deposit, the drilling company usually caps the well and moves on to other areas that may contain larger reserves and offer stronger economic incentives. Chemical and biological methods exist to purify these wells, but most are complex and costly. However, a group of scientists now is developing what could be a cheaper, easier method to clean up and utilize this polluted natural gas.The technique—which involves growing “enrichment” cultures of bacteria that metabolize the hydrogen sulfide into harmless compounds—could be particularly useful to poor and energy-starved developing nations, says Norman Wainwright, a senior scientist at the Woods Hole Marine Biological Laboratory. “We're hoping the technique can be robust enough and inexpensive enough to be used in a developing country,” Wainwright says. Other scientists involved with the project are Porter Anderson, a University of Rochester professor emeritus associated with the lab and Ben Ebenhack, also of Rochester.

  14. Work transitions.

    PubMed

    Fouad, Nadya A; Bynner, John

    2008-01-01

    Individuals make choices in, and adjust to, a world of work that is often a moving target. Because work is so central to human functioning, and transitions in and out of work can have major mental health repercussions, the authors argue that applied psychologists in health services need to understand those transitions. This article focuses on the different types of transition throughout a person's working life and the resources needed at different stages to ensure the success of these transitions. The authors start by examining the roles of capability and adaptability in supporting and facilitating adjustment to work transitions and their relation to identity development. They then examine the role of social and institutional contexts in shaping work transitions and their outcomes. The authors focus on voluntary versus involuntary transitions and then broaden the lens in discussing the policy implications of research on work transitions.

  15. [Drug access in poor countries].

    PubMed

    Sebbag, Robert

    2007-11-01

    As a responsible player in the global pharmaceutical industry, Sanofi-Aventis recognizes its special responsibility to provide poor countries with access to drugs and vaccines. This is a key component of the Group's approach to sustainable development. As such, the Access to Medicines department draws on Sanofi-Aventis' expertise in order to address major public health issues, starting with the treatment of malaria, tuberculosis, sleeping sickness, leishmaniasis and epilepsy, as well as access to vaccines. The department has four main activities: research and development of new drugs; improvement of existing treatments; information, communication and education of patients and healthcare professionals; and development of a differential pricing and distribution policy adapted to patients' income, with a "no profit-no loss" equilibrium.

  16. Serving the world's poor, profitably.

    PubMed

    Prahalad, C K; Hammond, Allen

    2002-09-01

    By stimulating commerce and development at the bottom of the economic pyramid, multi-nationals could radically improve the lives of billions of people and help create a more stable, less dangerous world. Achieving this goal does not require MNCs to spearhead global social-development initiatives for charitable purposes. They need only act in their own self-interest. How? The authors lay out the business case for entering the world's poorest markets. Fully 65% of the world's population earns less than $2,000 per year--that's 4 billion people. But despite the vastness of this market, it remains largely untapped. The reluctance to invest is easy to understand, but it is, by and large, based on outdated assumptions of the developing world. While individual incomes may be low, the aggregate buying power of poor communities is actually quite large, representing a substantial market in many countries for what some might consider luxury goods like satellite television and phone services. Prices, and margins, are often much higher in poor neighborhoods than in their middle-class counterparts. And new technologies are already steadily reducing the effects of corruption, illiteracy, inadequate infrastructure, and other such barriers. Because these markets are in the earliest stages of economic development, revenue growth for multi-nationals entering them can be extremely rapid. MNCs can also lower costs, not only through low-cost labor but by transferring operating efficiencies and innovations developed to serve their existing operations. Certainly, succeeding in such markets requires MNCs to think creatively. The biggest change, though, has to come from executives: Unless business leaders confront their own preconceptions--particularly about the value of high-volume, low-margin businesses--companies are unlikely to master the challenges or reap the rewards of these developing markets.

  17. The slow collisional E×B ion drift characterized as the major instability mechanism of a poorly magnetized plasma column with an inward-directed radial electric field

    SciTech Connect

    Pierre, Thiéry

    2016-04-15

    The low-frequency instability of a cylindrical poorly magnetized plasma with an inward-directed radial electric field is studied changing the gas pressure and the ion cyclotron frequency. The unstable frequency always decreases when the gas pressure is increased indicating collisional effects. At a fixed pressure, the unstable frequency increases with the magnetic field when the B-field is low and decreases at larger magnetic field strength. We find that the transition between these two regimes is obtained when the ion cyclotron frequency equals the ion-neutrals collision frequency. This is in agreement with the theory of the slow-ion drift instability induced by the collisional slowing of the electric ion drift [A. Simon, Phys. Fluids 6, 382 (1963)].

  18. Poorly Understood Aspects of Striated Muscle Contraction

    PubMed Central

    Månsson, Alf

    2015-01-01

    Muscle contraction results from cyclic interactions between the contractile proteins myosin and actin, driven by the turnover of adenosine triphosphate (ATP). Despite intense studies, several molecular events in the contraction process are poorly understood, including the relationship between force-generation and phosphate-release in the ATP-turnover. Different aspects of the force-generating transition are reflected in the changes in tension development by muscle cells, myofibrils and single molecules upon changes in temperature, altered phosphate concentration, or length perturbations. It has been notoriously difficult to explain all these events within a given theoretical framework and to unequivocally correlate observed events with the atomic structures of the myosin motor. Other incompletely understood issues include the role of the two heads of myosin II and structural changes in the actin filaments as well as the importance of the three-dimensional order. We here review these issues in relation to controversies regarding basic physiological properties of striated muscle. We also briefly consider actomyosin mutation effects in cardiac and skeletal muscle function and the possibility to treat these defects by drugs. PMID:25961006

  19. Venus Transit

    NASA Image and Video Library

    2012-06-05

    It appeared that New Yorkers were not going to be able to see the transit of the planet Venus across the Sun, but just before the transit was over the sun broke through the clouds and Yvette Lee Kang was able to catch a glimpse of the transit on Tuesday, June 5, 2012 in New York. A transit of Venus occurs when the planet passes directly between the sun and earth. This alignment is rare, coming in pairs that are eight years apart but separated by over a century. The next Venus transit will be in December 2117. Photo Credit: (NASA/Bill Ingalls)

  20. Venus Transit

    NASA Image and Video Library

    2012-06-05

    It appeared that New Yorkers were not going to be able to see the transit of the planet Venus across the Sun, but just before the transit was over the sun broke through the clouds and Liz Heller and Andriel Mesznik were able to catch a glimpse of the transit on Tuesday, June 5, 2012 in New York. A transit of Venus occurs when the planet passes directly between the sun and earth. This alignment is rare, coming in pairs that are eight years apart but separated by over a century. The next Venus transit will be in December 2117. Photo Credit: (NASA/Bill Ingalls)

  1. Chemical abundances in metal-poor stars in Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Venn, Kim; Norris, John; Shetrone, Matthew

    2015-08-01

    Stars in low-mass dwarf galaxies show a larger range in their chemical properties than those in the Milky Way halo. Not only are alpha-poor stars found at lower metallicities, but also r-process challenged stars, and a disparate fraction of carbon-enhanced metal-poor stars. A more pristine and chemically inhomogeneous interstellar medium, combined with stoichastic star formation in a metal-poor environment, is thought to cause these detectable differences in the early SN II contributions. We are also now finding stars in dwarf galaxies that appear to be iron-enhanced, i.e., stars that have formed in pockets of SN Ia enriched gas. A comparison of their chemical abundances with individual SN Ia models can provide unique constraints on the SN Ia progenitors.

  2. DYNAMIC S0 GALAXIES. II. THE ROLE OF DIFFUSE HOT GAS

    SciTech Connect

    Li Jiangtao; Chen Yang; Daniel Wang, Q.; Li Zhiyuan

    2011-08-10

    Cold gas loss is thought to be important in star formation quenching and morphological transition during the evolution of S0 galaxies. In high-density environments, this gas loss can be achieved via many external mechanisms. However, in relatively isolated environments, where these external mechanisms cannot be efficient, the gas loss must then be dominated by some internal processes. We have performed Chandra analysis of hot gas in five nearby isolated S0 galaxies, based on the quantitative subtraction of various stellar contributions. We find that all the galaxies studied in the present work are X-ray faint, with the luminosity of the hot gas (L{sub X} ) typically accounting for {approx}< 5% of the expected Type Ia supernova (SN) energy injection rate. We have further compared our results with those from relevant recent papers, in order to investigate the energy budget, cold-hot gas relation, and gas removal from S0 galaxies in isolated environments. We find that elliptical and S0 galaxies are not significantly different in L{sub X} at the low-mass end (typically with K-band luminosity L{sub K} {approx}< 10{sup 11} L{sub sun,K}). However, at the high-mass end, S0 galaxies tend to have significantly lower L{sub X} than elliptical galaxies of the same stellar masses, as already shown in previous observational and theoretical works. We further discuss the potential relationship of the diffuse X-ray emission with the cold (atomic and molecular) gas content in the S0 and elliptical galaxies included in our study. We find that L{sub X} /L{sup 2}{sub K} tends to correlate positively with the total cold gas mass (M{sub H{sub 2}+H{sub i}}) for cold-gas-poor galaxies with M{sub H{sub 2}+H{sub i}}{approx}<10{sup 8} M{sub sun}, while they anti-correlate with each other for cold-gas-rich galaxies. This cold-hot gas relationship can be explained in a scenario of early-type galaxy evolution, with the leftover cold gas from the precursor star-forming galaxy mainly removed by the

  3. Factors influencing doping control and abrupt metallurgical transitions during atmospheric pressure MOVPE growth of AlGaAs and GaAs

    NASA Astrophysics Data System (ADS)

    Roberts, J. S.; Mason, N. J.; Robinson, M.

    1984-09-01

    Atmospheric pressure MOVPE of GaAs and AlGaAs has been investigated using two gas handling systems and a conventional horizontal reactor. Initially a simple source/carrier gas manifold design was assessed but severe retention of reagents in the pipework resulted in poor control of doping and interface abruptness. However, integration of the reagent and carrier gas in a pressure balanced vent/run configuration gave a significant improvement. AlGaAs/GaAs multilayers and n +/n - GaAs transitions have been used to assess the performance of both systems. Abrupt p-type doping transitions using bis-cyclopentadienylmagnesium proved unsuccessful as long doping tails were observed.

  4. Transitional Care

    ERIC Educational Resources Information Center

    Naylor, Mary; Keating, Stacen A.

    2008-01-01

    Transitional care encompasses a broad range of services and environments designed to promote the safe and timely passage of patients between levels of health care and across care settings. High-quality transitional care is especially important for older adults with multiple chronic conditions and complex therapeutic regimens, as well as for their…

  5. Transitional Care

    ERIC Educational Resources Information Center

    Naylor, Mary; Keating, Stacen A.

    2008-01-01

    Transitional care encompasses a broad range of services and environments designed to promote the safe and timely passage of patients between levels of health care and across care settings. High-quality transitional care is especially important for older adults with multiple chronic conditions and complex therapeutic regimens, as well as for their…

  6. Influence of Transition Metal Cationization versus Sodium Cationization and Protonation on the Gas-Phase Tautomeric Conformations and Stability of Uracil: Application to [Ura+Cu]+ and [Ura+Ag]+

    NASA Astrophysics Data System (ADS)

    Akinyemi, T. E.; Wu, R. R.; Nei, Y.-W.; Cunningham, N. A.; Roy, H. A.; Steill, J. D.; Berden, G.; Oomens, J.; Rodgers, M. T.

    2017-09-01

    The gas-phase conformations of transition metal cation-uracil complexes, [Ura+Cu]+ and [Ura+Ag]+, were examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra were measured over the IR fingerprint and hydrogen-stretching regions. Structures and linear IR spectra of the stable tautomeric conformations of these complexes were initially determined at the B3LYP/6-31G(d) level. The four most stable structures computed were also examined at the B3LYP/def2-TZVPPD level to improve the accuracy of the predicted IR spectra. Two very favorable modes of binding are found for [Ura+Cu]+ and [Ura+Ag]+ that involve O2N3 bidentate binding to the 2-keto-4-hydroxy minor tautomer and O4 monodentate binding to the canonical 2,4-diketo tautomer of Ura. Comparisons between the measured IRMPD and calculated IR spectra enable elucidation of the conformers present in the experiments. These comparisons indicate that both favorable binding modes are represented in the experimental tautomeric conformations of [Ura+Cu]+ and [Ura+Ag]+. B3LYP suggests that Cu+ exhibits a slight preference for O4 binding, whereas Ag+ exhibits a slight preference for O2N3 binding. In contrast, MP2 suggests that both Cu+ and Ag+ exhibit a more significant preference for O2N3 binding. The relative band intensities suggest that O4 binding conformers comprise a larger portion of the population for [Ura+Ag]+ than [Ura+Cu]+. The dissociation behavior and relative stabilities of the [Ura+M]+ complexes, M+ = Cu+, Ag+, H+, and Na+) are examined via energy-resolved collision-induced dissociation experiments. The IRMPD spectra, dissociation behaviors, and binding preferences of Cu+ and Ag+ are compared with previous and present results for those of H+ and Na+. [Figure not available: see fulltext.

  7. Influence of Transition Metal Cationization versus Sodium Cationization and Protonation on the Gas-Phase Tautomeric Conformations and Stability of Uracil: Application to [Ura+Cu](+) and [Ura+Ag]().

    PubMed

    Akinyemi, T E; Wu, R R; Nei, Y-W; Cunningham, N A; Roy, H A; Steill, J D; Berden, G; Oomens, J; Rodgers, M T

    2017-09-11

    The gas-phase conformations of transition metal cation-uracil complexes, [Ura+Cu](+) and [Ura+Ag](+), were examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra were measured over the IR fingerprint and hydrogen-stretching regions. Structures and linear IR spectra of the stable tautomeric conformations of these complexes were initially determined at the B3LYP/6-31G(d) level. The four most stable structures computed were also examined at the B3LYP/def2-TZVPPD level to improve the accuracy of the predicted IR spectra. Two very favorable modes of binding are found for [Ura+Cu](+) and [Ura+Ag](+) that involve O2N3 bidentate binding to the 2-keto-4-hydroxy minor tautomer and O4 monodentate binding to the canonical 2,4-diketo tautomer of Ura. Comparisons between the measured IRMPD and calculated IR spectra enable elucidation of the conformers present in the experiments. These comparisons indicate that both favorable binding modes are represented in the experimental tautomeric conformations of [Ura+Cu](+) and [Ura+Ag](+). B3LYP suggests that Cu(+) exhibits a slight preference for O4 binding, whereas Ag(+) exhibits a slight preference for O2N3 binding. In contrast, MP2 suggests that both Cu(+) and Ag(+) exhibit a more significant preference for O2N3 binding. The relative band intensities suggest that O4 binding conformers comprise a larger portion of the population for [Ura+Ag](+) than [Ura+Cu](+). The dissociation behavior and relative stabilities of the [Ura+M](+) complexes, M(+) = Cu(+), Ag(+), H(+), and Na(+)) are examined via energy-resolved collision-induced dissociation experiments. The IRMPD spectra, dissociation behaviors, and binding preferences of Cu(+) and Ag(+) are compared with previous and present results for those of H(+) and Na(+). Graphical Abstract ᅟ.

  8. Effect of adduct formation with molecular nitrogen on the measured collisional cross sections of transition metal-1,10-phenanthroline complexes in traveling wave ion-mobility spectrometry: N2 is not always an "inert" buffer gas.

    PubMed

    Rijs, Nicole J; Weiske, Thomas; Schlangen, Maria; Schwarz, Helmut

    2015-10-06

    The number of separations and analyses of molecular species using traveling wave ion-mobility spectrometry-mass spectrometry (TWIMS-MS) is increasing, including those extending the technique to analytes containing metal atoms. A critical aspect of such applications of TWIMS-MS is the validity of the collisional cross sections (CCSs) measured and whether they can be accurately calibrated against other ion-mobility spectrometry (IMS) techniques. Many metal containing species have potential reactivity toward molecular nitrogen, which is present in high concentration in the typical Synapt-G2 TWIMS cell. Here, we analyze the effect of nitrogen on the drift time of a series of cationic 1,10-phenanthroline complexes of the late transition metals, [(phen)M](+), (M = Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, and Hg) in order to understand potential deviations from expected drift time behaviors. These metal complexes were chosen for their metal open-coordination site and lack of rotameric species. The target species were generated via electrospray ionization (ESI), analyzed using TWIMS in N2 drift gas, and the observed drift time trends compared. Theoretically derived CCSs for all species (via both the projection approximation and trajectory method) were also compared. The results show that, indeed, for metal containing species in this size regime, reaction with molecular nitrogen has a dramatic effect on measured drift times and must not be ignored when comparing and interpreting TWIMS arrival time distributions. Density-functional theory (DFT) calculations are employed to analyze the periodic differences due to the metal's interaction with nitrogen (and background water) in detail.

  9. Role of stranded gas in increasing global gas supplies

    USGS Publications Warehouse

    Attanasi, E.D.; Freeman, P.A.

    2013-01-01

    This report synthesizes the findings of three regional studies in order to evaluate, at the global scale, the contribution that stranded gas resources can make to global natural gas supplies. Stranded gas, as defined for this study, is natural gas in discovered conventional gas and oil fields that is currently not commercially producible for either physical or economic reasons. The regional studies evaluated the cost of bringing the large volumes of undeveloped gas in stranded gas fields to selected markets. In particular, stranded gas fields of selected Atlantic Basin countries, north Africa, Russia, and central Asia are screened to determine whether the volumes are sufficient to meet Europe’s increasing demand for gas imports. Stranded gas fields in Russia, central Asia, Southeast Asia, and Australia are also screened to estimate development, production, and transport costs and corresponding gas volumes that could be supplied to Asian markets in China, India, Japan, and South Korea. The data and cost analysis presented here suggest that for the European market and the markets examined in Asia, the development of stranded gas provides a way to meet projected gas import demands for the 2020-to-2040 period. Although this is a reconnaissance-type appraisal, it is based on volumes of gas that are associated with individual identified fields. Individual field data were carefully examined. Some fields were not evaluated because current technology was insufficient or it appeared the gas was likely to be held off the export market. Most of the evaluated stranded gas can be produced and delivered to markets at costs comparable to historical prices. Moreover, the associated volumes of gas are sufficient to provide an interim supply while additional technologies are developed to unlock gas diffused in shale and hydrates or while countries transition to making a greater use of renewable energy sources.

  10. Gas Chromatography

    NASA Astrophysics Data System (ADS)

    Qian, Michael C.

    Gas chromatography (GC) has many applications in the analysis of food products. GC has been used for the determination of fatty acids, triglycerides, cholesterol, gases, water, alcohols, pesticides, flavor compounds, and many more. While GC has been used for other food components such as sugars, oligosaccharides, amino acids, peptides, and vitamins, these substances are more suited to analysis by high performance liquid chromatography. GC is ideally suited to the analysis of volatile substances that are thermally stable. Substances such as pesticides and flavor compounds that meet these criteria can be isolated from a food and directly injected into the GC. For compounds that are thermally unstable, too low in volatility, or yield poor chromatographic separation due to polarity, a derivatization step must be done before GC analysis. The two parts of the experiment described here include the analysis of alcohols that requires no derivatization step, and the analysis of fatty acids which requires derivatization. The experiments specify the use of capillary columns, but the first experiment includes conditions for a packed column.

  11. Family Structure and Employment Characteristics Differentiate Poor from Near-Poor Workers.

    ERIC Educational Resources Information Center

    Dagata, Elizabeth M.

    1997-01-01

    Current Population Survey data indicate that rural workers were more likely than urban workers to be poor or near-poor. Poor and near-poor rural workers were more likely than other workers to be southern, young, and in a minority group. Barriers to livable-wage employment included low educational attainment, being a single mother, and having young…

  12. Do Middle-Class Students Perceive Poor Women and Poor Men Differently?

    ERIC Educational Resources Information Center

    Cozzarelli, Catherine; Tagler, Michael J.; Wilkinson, Anna V.

    2002-01-01

    Examined college students' attitudes and stereotypes regarding poor women, attributions for their poverty, and whether those thoughts and feelings differed from those about poor men. Attitudes and stereotypes were significantly more positive regarding poor women than poor men. Participants endorsed internal attributions for both women's and men's…

  13. Modeling of transitional flows

    NASA Technical Reports Server (NTRS)

    Lund, Thomas S.

    1988-01-01

    An effort directed at developing improved transitional models was initiated. The focus of this work was concentrated on the critical assessment of a popular existing transitional model developed by McDonald and Fish in 1972. The objective of this effort was to identify the shortcomings of the McDonald-Fish model and to use the insights gained to suggest modifications or alterations of the basic model. In order to evaluate the transitional model, a compressible boundary layer code was required. Accordingly, a two-dimensional compressible boundary layer code was developed. The program was based on a three-point fully implicit finite difference algorithm where the equations were solved in an uncoupled manner with second order extrapolation used to evaluate the non-linear coefficients. Iteration was offered as an option if the extrapolation error could not be tolerated. The differencing scheme was arranged to be second order in both spatial directions on an arbitrarily stretched mesh. A variety of boundary condition options were implemented including specification of an external pressure gradient, specification of a wall temperature distribution, and specification of an external temperature distribution. Overall the results of the initial phase of this work indicate that the McDonald-Fish model does a poor job at predicting the details of the turbulent flow structure during the transition region.

  14. Hibernation and gas exchange.

    PubMed

    Milsom, William K; Jackson, Donald C

    2011-01-01

    Hibernation in endotherms and ectotherms is characterized by an energy-conserving metabolic depression due to low body temperatures and poorly understood temperature-independent mechanisms. Rates of gas exchange are correspondly reduced. In hibernating mammals, ventilation falls even more than metabolic rate leading to a relative respiratory acidosis that may contribute to metabolic depression. Breathing in some mammals becomes episodic and in some small mammals significant apneic gas exchange may occur by passive diffusion via airways or skin. In ectothermic vertebrates, extrapulmonary gas exchange predominates and in reptiles and amphibians hibernating underwater accounts for all gas exchange. In aerated water diffusive exchange permits amphibians and many species of turtles to remain fully aerobic, but hypoxic conditions can challenge many of these animals. Oxygen uptake into blood in both endotherms and ectotherms is enhanced by increased affinity of hemoglobin for O₂ at low temperature. Regulation of gas exchange in hibernating mammals is predominately linked to CO₂/pH, and in episodic breathers, control is principally directed at the duration of the apneic period. Control in submerged hibernating ectotherms is poorly understood, although skin-diffusing capacity may increase under hypoxic conditions. In aerated water blood pH of frogs and turtles either adheres to alphastat regulation (pH ∼8.0) or may even exhibit respiratory alkalosis. Arousal in hibernating mammals leads to restoration of euthermic temperature, metabolic rate, and gas exchange and occurs periodically even as ambient temperatures remain low, whereas body temperature, metabolic rate, and gas exchange of hibernating ectotherms are tightly linked to ambient temperature.

  15. Inefficient star formation in extremely metal poor galaxies.

    PubMed

    Shi, Yong; Armus, Lee; Helou, George; Stierwalt, Sabrina; Gao, Yu; Wang, Junzhi; Zhang, Zhi-Yu; Gu, Qiusheng

    2014-10-16

    The first galaxies contain stars born out of gas with few or no 'metals' (that is, elements heavier than helium). The lack of metals is expected to inhibit efficient gas cooling and star formation, but this effect has yet to be observed in galaxies with an oxygen abundance (relative to hydrogen) below a tenth of that of the Sun. Extremely metal poor nearby galaxies may be our best local laboratories for studying in detail the conditions that prevailed in low metallicity galaxies at early epochs. Carbon monoxide emission is unreliable as a tracer of gas at low metallicities, and while dust has been used to trace gas in low-metallicity galaxies, low spatial resolution in the far-infrared has typically led to large uncertainties. Here we report spatially resolved infrared observations of two galaxies with oxygen abundances below ten per cent of the solar value, and show that stars formed very inefficiently in seven star-forming clumps in these galaxies. The efficiencies are less than a tenth of those found in normal, metal rich galaxies today, suggesting that star formation may have been very inefficient in the early Universe.

  16. Quantifying capture efficiency of gas collection wells with gas tracers.

    PubMed

    Yazdani, Ramin; Imhoff, Paul; Han, Byunghyun; Mei, Changen; Augenstein, Don

    2015-09-01

    A new in situ method for directly measuring the gas collection efficiency in the region around a gas extraction well was developed. Thirteen tests were conducted by injecting a small volume of gas tracer sequentially at different locations in the landfill cell, and the gas tracer mass collected from each test was used to assess the collection efficiency at each injection point. For 11 tests the gas collection was excellent, always exceeding 70% with seven tests showing a collection efficiency exceeding 90%. For one test the gas collection efficiency was 8±6%. Here, the poor efficiency was associated with a water-laden refuse or remnant daily cover soil located between the point of tracer injection and the extraction well. The utility of in situ gas tracer tests for quantifying landfill gas capture at particular locations within a landfill cell was demonstrated. While there are certainly limitations to this technology, this method may be a valuable tool to help answer questions related to landfill gas collection efficiency and gas flow within landfills. Quantitative data from tracer tests may help assess the utility and cost-effectiveness of alternative cover systems, well designs and landfill gas collection management practices. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. GAS EMISSIONS IN PLANCK COLD DUST CLUMPS-A SURVEY OF THE J = 1-0 TRANSITIONS OF {sup 12}CO, {sup 13}CO, AND C{sup 18}O

    SciTech Connect

    Wu Yuefang; Liu Tie; Meng, Fanyi; Li Di; Qin Shengli; Ju Binggang

    2012-09-01

    A survey toward 674 Planck cold clumps of the Early Cold Core Catalogue (ECC) in the J = 1-0 transitions of {sup 12}CO, {sup 13}CO, and C{sup 18}O has been carried out using the Purple Mountain Observatory 13.7 m telescope. Six hundred seventy-three clumps were detected with {sup 12}CO and {sup 13}CO emission, and 68% of the sample has C{sup 18}O emission. Additional velocity components were also identified. A close consistency of the three line peak velocities was revealed for the first time. Kinematic distances are given for all the velocity components, and half of the clumps are located within 0.5 and 1.5 kpc. Excitation temperatures range from 4 to 27 K, slightly larger than those of T{sub d} . Line width analysis shows that the majority of ECC clumps are low-mass clumps. Column densities N{sub H{sub 2}} span from 10{sup 20} to 4.5 Multiplication-Sign 10{sup 22} cm{sup -2} with an average value of (4.4 {+-} 3.6) Multiplication-Sign 10{sup 21} cm{sup -2}. N{sub H{sub 2}} cumulative fraction distribution deviates from the lognormal distribution, which is attributed to optical depth. The average abundance ratio of the {sup 13}CO to C{sup 18}O in these clumps is 7.0 {+-} 3.8, higher than the terrestrial value. Dust and gas are well coupled in 95% of the clumps. Blue profile asymmetry, red profile asymmetry, and total line asymmetry were found in less than 10% of the clumps, generally indicating that star formation is not yet developed. Ten clumps were mapped. Twelve velocity components and 22 cores were obtained. Their morphologies include extended diffuse, dense, isolated, cometary, and filament, of which the last is the majority. Twenty cores are starless, and only seven cores seem to be in a gravitationally bound state. Planck cold clumps are the most quiescent among the samples of weak red IRAS, infrared dark clouds, UC H II candidates, extended green objects, and methanol maser sources, suggesting that Planck cold clumps have expanded the horizon of cold

  18. Using Story to Help Student Understanding of Gas Behavior

    ERIC Educational Resources Information Center

    Wiebe, Rick; Stinner, Arthur

    2010-01-01

    Students tend to have a poor understanding of the concept of gas pressure. Usually, gas pressure is taught in terms of the various formulaic gas laws. The development of the concept of gas pressure according to the early Greeks did not include the concept of a vacuum. It was not for another 2000 years that Torricelli proposed that a vacuum can…

  19. Using Story to Help Student Understanding of Gas Behavior

    ERIC Educational Resources Information Center

    Wiebe, Rick; Stinner, Arthur

    2010-01-01

    Students tend to have a poor understanding of the concept of gas pressure. Usually, gas pressure is taught in terms of the various formulaic gas laws. The development of the concept of gas pressure according to the early Greeks did not include the concept of a vacuum. It was not for another 2000 years that Torricelli proposed that a vacuum can…

  20. The Crisis of the Near Poor

    ERIC Educational Resources Information Center

    Newman, Katherine S.; Tan Chen, Victor

    2007-01-01

    This article focuses on the "missing class," the near poor whose incomes place them above the poverty line, but well below the middle class. Near-poor families with two parents and two children subsist on $20,000 to $40,000 a year, which disqualifies them for virtually all public subsidies, but is a far cry from what they need to be…

  1. Cognitive Profiles of Korean Poor Readers

    ERIC Educational Resources Information Center

    Cho, Jeung-Ryeul; Ji, Yu-Kyong

    2011-01-01

    This study compared the performance of 30 poor readers in the third grade with those of 30 average readers of the same age and 30 younger readers matched with the same reading level on phonological, visuo-perceptual, orthographic, and naming speed tasks. Individual data revealed heterogeneous profiles for the poor readers: six (20%) exhibited…

  2. RADAR OBSERVATION CONDITIONS OF POOR VISIBILITY,

    DTIC Science & Technology

    Ship navigational radar is an effective means for revealing above-water objects in conditions of poor visibility. A radar image of the surrounding...radar observation and with the competent operation of the set, radar is a reliable means of detection of encountered vessels in conditions of poor

  3. Poor Rural Children Attract Close Study

    ERIC Educational Resources Information Center

    Viadero, Debra

    2008-01-01

    Growing up poor in isolated rural areas and small towns is qualitatively different from growing up poor in the city. Yet most of what experts know about the effects of poverty on children's development comes from studies conducted in big cities. Now, an ambitious project run by universities in Pennsylvania and North Carolina is putting what some…

  4. Phonological Coding in Good and Poor Readers.

    ERIC Educational Resources Information Center

    Briggs, Pamela; Underwood, Geoffrey

    1982-01-01

    A set of four experiments investigates the relationship between phonological coding and reading ability, using a picture-word interference task and a decoding task. Results with regard to both adults and children suggest that while poor readers possess weak decoding skills, good and poor readers show equivalent evidence of direct semantic and…

  5. BIRTH CONTROL, CULTURE AND THE POOR.

    ERIC Educational Resources Information Center

    RIESSMAN, CATHERINE KOHLER

    EVIDENCE FROM STUDIES INDICATE THAT THE POOR DESIRE TO CONTROL THEIR FAMILY SIZE AND PREFER TO USE BIRTH CONTROL DEVICES (PILLS OR INTERUTERINE DEVICES) WHICH ARE NOT COITUS-CONNECTED AND ANTITHETICAL TO THEIR SEXUAL ATTITUDES AND TRADITIONS. CONTRARY TO THE BELIEF THAT THE POOR ARE LESS LIKELY TO UTILIZE EXISTING HEALTH FACILITIES OR TO TAKE PART…

  6. The Crisis of the Near Poor

    ERIC Educational Resources Information Center

    Newman, Katherine S.; Tan Chen, Victor

    2007-01-01

    This article focuses on the "missing class," the near poor whose incomes place them above the poverty line, but well below the middle class. Near-poor families with two parents and two children subsist on $20,000 to $40,000 a year, which disqualifies them for virtually all public subsidies, but is a far cry from what they need to be…

  7. The Chronically Poor: Breaking the Cycle.

    ERIC Educational Resources Information Center

    Morris-Bilotti, Sharon

    This question-and-answer format paper looks at some of the basic issues surrounding the chronically poor and initiatives and services designed to break the poverty cycle. A first section explores some of the myths and realities surrounding the characteristics of the chronically poor population and notes that this population is comprised of…

  8. Poor Rural Children Attract Close Study

    ERIC Educational Resources Information Center

    Viadero, Debra

    2008-01-01

    Growing up poor in isolated rural areas and small towns is qualitatively different from growing up poor in the city. Yet most of what experts know about the effects of poverty on children's development comes from studies conducted in big cities. Now, an ambitious project run by universities in Pennsylvania and North Carolina is putting what some…

  9. Cognitive Profiles of Korean Poor Readers

    ERIC Educational Resources Information Center

    Cho, Jeung-Ryeul; Ji, Yu-Kyong

    2011-01-01

    This study compared the performance of 30 poor readers in the third grade with those of 30 average readers of the same age and 30 younger readers matched with the same reading level on phonological, visuo-perceptual, orthographic, and naming speed tasks. Individual data revealed heterogeneous profiles for the poor readers: six (20%) exhibited…

  10. Time estimation in good and poor sleepers.

    PubMed

    Fichten, Catherine S; Creti, Laura; Amsel, Rhonda; Bailes, Sally; Libman, Eva

    2005-12-01

    Time estimation was examined in 148 older good and poor sleepers in analogue and naturalistic sleep settings. On analogue tasks, both "empty" time and time listening to an audiobook were overestimated by both good and poor sleepers. There were no differences between groups. "Empty" time was experienced as "dragging." In the sleep setting, most poor sleepers underestimated nocturnal sleep and overestimated awake times related to their own sleep problem: sleep onset vs. sleep maintenance insomnia. Good sleepers did the opposite. Severity of sleep problem and size of time estimation errors were unrelated. Greater night-to-night wake time variability was experienced by poor than by good sleepers. Psychological adjustment was unrelated to time estimations and to magnification or minimization of sleep problems. The results suggest that for poor sleepers who magnify their sleep problem, self-monitoring can be of benefit by demonstrating that the sleep problem is not as severe as believed.

  11. Hepatitis A: epidemiology in resource-poor countries.

    PubMed

    Aggarwal, Rakesh; Goel, Amit

    2015-10-01

    Transmission of hepatitis A virus (HAV) infection is primarily fecal-oral. Symptomatic hepatitis, severe disease, and death are more likely to occur when infection occurs at an older age. Improvements in socioeconomic and hygienic conditions have led to a change in its epidemiology worldwide. In the last two decades, improved hygiene in several resource-poor countries has led to reduced transmission of HAV, an increase in average age at infection, and, consequently, a paradoxical increase in morbidity and mortality because of hepatitis A. In Argentina, introduction of one dose (instead of the conventional two doses, to reduce costs) of inactivated HAV vaccine at 12-month age in a universal childhood immunization program during such 'epidemiologic transition' has markedly reduced the incidence of symptomatic hepatitis A, and of fulminant hepatitis and liver transplantation caused by HAV infection. The monetary value of medical and nonmedical benefits of this strategy outweighed the expenditure on vaccination. These excellent results were possibly contingent upon a high vaccination coverage. Resource-poor countries should closely monitor the epidemiology of HAV infection and periodically undertake cost-effectiveness analyses of HAV immunization strategies. This should allow timely identification of epidemiologic transition and introduction of preventive strategies before HAV infection becomes a public health problem.

  12. Dynamics of stimulated L → H transitions

    SciTech Connect

    Miki, K.; Diamond, P. H.; Xiao, W. W.; Hahn, S.-H.; Gürcan, Ö. D.; Tynan, G. R.

    2013-08-15

    We report on model studies of stimulated L → H transitions [K. Miki et al., Phys. Rev. Lett. 110, 195002 (2013)]. These studies use a reduced mesoscale model. Model studies reveal that L → H transition can be triggered by particle injection into a subcritical state (i.e., Ptransition. For low ambient heating, strong injection is predicted to trigger a transient turbulence collapse. Repetitive injection at a period less than the lifetime of the collapsed state can thus maintain the turbulence collapse and so sustain a driven H-mode-like state. The total number of particles required to induce a transition by either injection or gas puffing is estimated. Results indicate that the total number of injected particles required is much smaller than that required for a transition by gas puffing. We thus show that internal injection is more efficient than gas puffing of comparable strength. We also observe that zonal flows do not play a critical role in stimulated transitions. For spontaneous transitions, the spike of the Reynolds work of turbulence on the zonal flow precedes the spike in the mean electric field shear. In contrast, we show that the two are coincident for stimulated transitions, suggesting that there is no causal link between zonal and mean flows for stimulated transitions.

  13. Gas separating

    DOEpatents

    Gollan, Arye Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  14. Gas separating

    DOEpatents

    Gollan, Arye

    1988-01-01

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  15. Star formation sustained by gas accretion

    NASA Astrophysics Data System (ADS)

    Sánchez Almeida, Jorge; Elmegreen, Bruce G.; Muñoz-Tuñón, Casiana; Elmegreen, Debra Meloy

    2014-07-01

    Numerical simulations predict that metal-poor gas accretion from the cosmic web fuels the formation of disk galaxies. This paper discusses how cosmic gas accretion controls star formation, and summarizes the physical properties expected for the cosmic gas accreted by galaxies. The paper also collects observational evidence for gas accretion sustaining star formation. It reviews evidence inferred from neutral and ionized hydrogen, as well as from stars. A number of properties characterizing large samples of star-forming galaxies can be explained by metal-poor gas accretion, in particular, the relationship among stellar mass, metallicity, and star-formation rate (the so-called fundamental metallicity relationship). They are put forward and analyzed. Theory predicts gas accretion to be particularly important at high redshift, so indications based on distant objects are reviewed, including the global star-formation history of the universe, and the gas around galaxies as inferred from absorption features in the spectra of background sources.

  16. A study of cooling flows in poor clusters of galaxies

    NASA Technical Reports Server (NTRS)

    Kriss, Gerard A.; Dillingham, Stephen

    1995-01-01

    We observed three poor clusters with central dominant galaxies (AWM 4, MKW 4, and MKW 3's) using the Position Sensitive Proportional Counter on the ROSAT X-ray satellite. The images reveal smooth, symmetrical X-ray emission filling the cluster with a sharp peak on each central galaxy. The cluster surface brightness profiles can be decomposed using superposed King models for the central galaxy and the intracluster medium. The King model parameters for the cluster portions are consistent with previous observations of these clusters. The newly measured King model parameters for the central galaxies are typical of the X-ray surface brightness distributions of isolated elliptical galaxies. Spatially resolved temperature measurements in annular rings throughout the clusters show a nearly isothermal profile. Temperatures are consistent with previously measured values, but are much better determined. There is no significant drop in temperature noted in the innermost bins where cooling flows are likely to be present, nor is any excess absorption by cold gas required. All cold gas columns are consistent with galactic foreground absorption. We derive mass profiles for the clusters assuming both isothermal temperature profiles and cooling flow models with constant mass flow rates. Our results are consistent with previous Einstein IPC observations by Kriss, Cioffi, & Canizares, but extend the mass profiles out to 1 Mpc in these poor clusters.

  17. Formaldehyde in Absorption: Tracing Molecular Gas in Early-Type Galaxies

    NASA Astrophysics Data System (ADS)

    Dollhopf, Niklaus M.; Donovan Meyer, Jennifer

    2016-01-01

    Early-Type Galaxies (ETGs) have been long-classified as the red, ellipsoidal branch of the classic Hubble tuning fork diagram of galactic structure. In part with this classification, ETGs are thought to be molecular and atomic gas-poor with little to no recent star formation. However, recent efforts have questioned this ingrained classification. Most notably, the ATLAS3D survey of 260 ETGs within ~40 Mpc found 22% contain CO, a common tracer for molecular gas. The presence of cold molecular gas also implies the possibility for current star formation within these galaxies. Simulations do not accurately predict the recent observations and further studies are necessary to understand the mechanisms of ETGs.CO traces molecular gas starting at densities of ~102 cm-3, which makes it a good tracer of bulk molecular gas, but does little to constrain the possible locations of star formation within the cores of dense molecular gas clouds. Formaldehyde (H2CO) traces molecular gas on the order of ~104 cm-3, providing a further constraint on the location of star-forming gas, while being simple enough to possibly be abundant in gas-poor ETGs. In cold molecular clouds at or above ~104 cm-3 densities, the structure of formaldehyde enables a phenomenon in which rotational transitions have excitation temperatures driven below the temperature of the cosmic microwave background (CMB), ~2.7 K. Because the CMB radiates isotropically, formaldehyde can be observed in absorption, independent of distance, as a tracer of moderately-dense molecular clouds and star formation.This novel observation technique of formaldehyde was incorporated for observations of twelve CO-detected ETGs from the ATLAS3D sample, including NGC 4710 and PGC 8815, to investigate the presence of cold molecular gas, and possible star formation, in ETGs. We present images from the Very Large Array, used in its C-array configuration, of the J = 11,0 - 11,1 transition of formaldehyde towards these sources. We report our

  18. THE KENNICUTT–SCHMIDT RELATION IN EXTREMELY METAL-POOR DWARF GALAXIES

    SciTech Connect

    Filho, M. E.; Almeida, J. Sánchez; Muñoz-Tuñón, C.; Amorín, R.; Elmegreen, B. G.; Elmegreen, D. M.

    2016-04-01

    The Kennicutt–Schmidt (KS) relation between the gas mass and star formation rate (SFR) describes the star formation regulation in disk galaxies. It is a function of gas metallicity, but the low-metallicity regime of the KS diagram is poorly sampled. We have analyzed data for a representative set of extremely metal-poor galaxies (XMPs), as well as auxiliary data, and compared these to empirical and theoretical predictions. The majority of the XMPs possess high specific SFRs, similar to high-redshift star-forming galaxies. On the KS plot, the XMP H i data occupy the same region as dwarfs and extend the relation for low surface brightness galaxies. Considering the H i gas alone, a considerable fraction of the XMPs already fall off the KS law. Significant quantities of “dark” H{sub 2} mass (i.e., not traced by CO) would imply that XMPs possess low star formation efficiencies (SFE{sub gas}). Low SFE{sub gas} in XMPs may be the result of the metal-poor nature of the H i gas. Alternatively, the H i reservoir may be largely inert, the star formation being dominated by cosmological accretion. Time lags between gas accretion and star formation may also reduce the apparent SFE{sub gas}, as may galaxy winds, which can expel most of the gas into the intergalactic medium. Hence, on global scales, XMPs could be H i-dominated, high-specific-SFR (≳10{sup −10} yr{sup −1}), low-SFE{sub gas} (≲10{sup −9} yr{sup −1}) systems, in which the total H i mass is likely not a good predictor of the total H{sub 2} mass, nor of the SFR.

  19. Energy and minorities, women, and the poor

    SciTech Connect

    Perry, H.L.; Perry, E.B.

    1980-01-01

    A comprehensive, up-to-date (1975 to 1980) bibliography of articles, books and other publications is presented dealing with the subject of energy and minorities, women and the poor. Included are academic, popular, and government publications as well as publications by private groups and organizations. It is intended for political scientists, sociologists, economists, home economists, energy planners, energy managers and others interested in the interface of minorities, women, and the poor with energy. Following a brief introduction, there is a general listing. Also included are references dealing with energy and black Americans, native Americans (Indians), the poor, and women. (MJJ)

  20. Transition operators

    NASA Astrophysics Data System (ADS)

    Alcock-Zeilinger, J.; Weigert, H.

    2017-05-01

    In this paper, we give a generic algorithm of the transition operators between Hermitian Young projection operators corresponding to equivalent irreducible representations of 𝖲𝖴 (N ) , using the compact expressions of Hermitian Young projection operators derived in the work of Alcock-Zeilinger and Weigert [eprint arXiv:1610.10088 [math-ph