scholarly journals Breaking the degeneracy between gas inflow and outflows with stellar metallicity: insights on M 101

2021 ◽  
Vol 502 (2) ◽  
pp. 1967-1973
Author(s):  
Xiaoyu Kang ◽  
Ruixiang Chang ◽  
Rolf-Peter Kudritzki ◽  
Xiaobo Gong ◽  
Fenghui Zhang
Keyword(s):  
Gas Phase ◽  
The Other ◽  
Model Parameters ◽  
Inflow Rate ◽  
Analysis Method ◽  
Mass Ratio ◽  
Disc Galaxy ◽  
Star Forming ◽  
Outflow Rate ◽  
Chemical Evolution Model

ABSTRACT An analytical chemical evolution model is constructed to investigate the radial distribution of gas-phase and stellar metallicity for star-forming galaxies. By means of the model, the gas-phase and stellar metallicity can be obtained from the stellar-to-gas mass ratio. Both the gas inflow and outflow processes play an important role in building the final gas-phase metallicity, and there exists degeneracy effect between the gas inflow and outflow rates for star-forming galaxies. On the other hand, stellar metallicity is more sensitive to the gas outflow rate than to the gas inflow rate, and this helps to break the parameter degeneracy for star-forming galaxies. We apply this analysis method to the nearby disc galaxy M 101 and adopting the classical χ2 methodology to explore the influence of model parameters on the resulted metallicity. It can be found that the combination of gas-phase and stellar metallicity is indeed more effective for constraining the gas inflow and outflow rates. Our results also show that the model with relatively strong gas outflows but weak gas inflow describes the evolution of M 101 reasonably well.

scholarly journals Destruction route of solid-state formamide by thermal H atoms

2020 ◽  
Vol 641 ◽  
pp. A88
Author(s):  
T. Suhasaria ◽  
V. Mennella
Keyword(s):  
Fourier Transform ◽  
Gas Phase ◽  
Cross Sections ◽  
The Other ◽  
Band Intensity ◽  
Isocyanic Acid ◽  
Simultaneous Increase ◽  
Reaction Sequence ◽  
Star Forming ◽  
Star Forming Regions

Context. Formamide (NH2CHO) is one of the simplest “CHON” molecules that has been observed in different environments in space. In star-forming regions, its abundance in the gas phase is correlated to isocyanic acid (HNCO), indicating a chemical relation between the two species. Many studies have investigated the different routes for the transformation of the two species from one to the other. Aims. We carry out an experimental analysis on the interaction of atomic H at 300 K with solid NH2CHO to probe whether HNCO can form. Methods. The effects of H atom irradiation on NH2CHO have been analyzed by Fourier-transform infrared spectroscopy. Results. During irradiation, a decrease in the band intensity of the C–H, C=O, and N–H modes of NH2CHO with a simultaneous increase in the N=C=O band intensity of HNCO is observed, indicating a transformation of NH2CHO to HNCO. The corresponding destruction and formation cross-sections have been estimated from the trend of the normalized column densities as a function of the H atom fluence. The transformation follows a three-step reaction sequence driven by H atom exothermic abstractions that also induce sputtering of the products. No bands of aminomethanol were detected. Conclusions. The interaction of H atoms with NH2CHO in space can be one of the promising mechanisms to explain the chemical relation between NH2CHO and HNCO. In addition, the comparison of our results with those of other energetic processing agents suggests that H atoms play a crucial role in the destruction of NH2CHO ice in dense regions of the interstellar medium.

scholarly journals Interacting galaxies in the IllustrisTNG simulations – II: star formation in the post-merger stage

2020 ◽  
Vol 493 (3) ◽  
pp. 3716-3731 ◽  
Author(s):  
Maan H Hani ◽  
Hayman Gosain ◽  
Sara L Ellison ◽  
David R Patton ◽  
Paul Torrey
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
Interacting Galaxies ◽  
Galaxy Mergers ◽  
Mass Ratio ◽  
Significant Progress ◽  
Star Forming ◽  
Wide Range ◽  
Binary Mergers ◽  
Minor Mergers

ABSTRACT Galaxy mergers are a major evolutionary transformation whose effects are borne out by a plethora of observations and numerical simulations. However, most previous simulations have used idealized, isolated, binary mergers and there has not been significant progress on studying statistical samples of galaxy mergers in large cosmological simulations. We present a sample of 27 691 post-merger (PM) galaxies (0c ≤ z ≤ 1) identified from IllustrisTNG: a cosmological, large box, magnetohydrodynamical simulation suite. The PM sample spans a wide range of merger and galaxy properties (M⋆, μ, fgas). We demonstrate that star-forming (SF) PMs exhibit enhanced star formation rates (SFRs) on average by a factor of ∼2, while the passive PMs show no statistical enhancement. We find that the SFR enhancements: (1) show no dependence on redshift, (2) anticorrelate with the PM’s stellar mass, and (3) correlate with the gas fraction of the PM’s progenitors. However, SF PMs show stronger enhancements which may indicate other processes being at play (e.g. gas phase, feedback efficiency). Although the SFR enhancement correlates mildly with the merger mass ratio, the more abundant minor mergers (0.1 ≤ μ < 0.3) still contribute ${\sim}50{{\ \rm per\ cent}}$ of the total SFR enhancement. By tracing the PM sample forward in time, we find that galaxy mergers can drive significant SFR enhancements which decay over ∼0.5 Gyr independent of the merger mass ratio, although the decay time-scale is dependent on the simulation resolution. The strongest merger-driven starburst galaxies evolve to be passive/quenched on faster time-scales than their controls.

Voronoi Analysis of a Soccer Game

2004 ◽  
Vol 9 (3) ◽  
pp. 233-240 ◽  
Author(s):  
S. Kim
Keyword(s):  
Collective Behavior ◽  
Quantitative Assessment ◽  
The Other ◽  
Analysis Method ◽  
Random System ◽  
Soccer Game ◽  
Voronoi Polygons ◽  
The Mean

This paper describes a Voronoi analysis method to analyze a soccer game. It is important for us to know the quantitative assessment of contribution done by a player or a team in the game as an individual or collective behavior. The mean numbers of vertices are reported to be 5–6, which is a little less than those of a perfect random system. Voronoi polygons areas can be used in evaluating the dominance of a team over the other. By introducing an excess Voronoi area, we can draw some fruitful results to appraise a player or a team rather quantitatively.

PENGARUH ABILITY, BENEVOLENCE DAN INTEGRITY TERHADAP TRUST, SERTA IMPLIKASINYA TERHADAP PARTISIPASI PELANGGAN E-COMMERCE: STUDI KASUS PADA PELANGGAN E-COMMERCE DI UBM

2017 ◽  
Vol 2 (2) ◽  
pp. 155-168 ◽  
Author(s):  
David Wong
Keyword(s):  
Data Analysis ◽  
Data Collection ◽  
Structural Equation Model ◽  
Structural Equation ◽  
Likert Scale ◽  
Equation Model ◽  
The Other ◽  
Predictor Variables ◽  
Analysis Method ◽  
Other Hand

This research aims at analyzing (1) the effect of vendor’s ability, benevolence, and integrity variables toward e-commerce customers’ trust in UBM; (2) the effect of vendor’s ability, benevolence, and integrity variables toward the level of e-commerce customers’ participation in Indonesia; and (3) the effect of trust variable toward level of e-commerce customers participation in UBM. This research makes use of UBM e-commerce users as research samples while using Likert scale questionnaire for data collection. Furthermore, the questionnaires are sent to as many as 200 respondents. For data analysis method, Structural Equation Model was used. Out of three predictor variables (ability, benevolence, and integrity), it is only vendor’s integrity that has a positive and significant effect on customers’ trust. On the other hand, it is only vendor’s integrity and customer’s trust that have a positive and significant effect on e-commerce customers’ participation in UBM. Keywords: e-commerce customers’ participation, ability, benevolence, integrity

A polycentric growth model of gallium arsenide epitaxial layers from the gas phase with simultaneous diffusion, adsorption and chemical reaction

1988 ◽  
Vol 53 (12) ◽  
pp. 2995-3013
Author(s):  
Emerich Erdös ◽  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma
Keyword(s):  
Growth Rate ◽  
Gallium Arsenide ◽  
Epitaxial Growth ◽  
Gas Phase ◽  
Surface Reaction ◽  
Quantitative Description ◽  
The Other ◽  
Rate Equations ◽  
Impact Interaction ◽  
Partial Pressures

For a quantitative description of the epitaxial growth rate of gallium arsenide, two models are proposed including two rate controlling steps, namely the diffusion of components in the gas phase and the surface reaction. In the models considered, the surface reaction involves a reaction triple - or quadruple centre. In both models three mechanisms are considered which differ one from the other by different adsorption - and impact interaction of reacting particles. In every of the six cases, the pertinent rate equations were derived, and the models have been confronted with the experimentally found dependences of the growth rate on partial pressures of components in the feed. The results are discussed with regard to the plausibility of individual mechanisms and of both models, and also with respect to their applicability and the direction of further investigations.

scholarly journals Theory and Applications of the Unit Gamma/Gompertz Distribution

Mathematics ◽  
2021 ◽  
Vol 9 (16) ◽  
pp. 1850
Author(s):  
Rashad A. R. Bantan ◽  
Farrukh Jamal ◽  
Christophe Chesneau ◽  
Mohammed Elgarhy
Keyword(s):  
Stochastic Ordering ◽  
Real Data ◽  
Rate Function ◽  
The Other ◽  
Likelihood Method ◽  
Model Parameters ◽  
Data Sets ◽  
Gompertz Distribution ◽  
Probability And Statistics ◽  
Analytical Behavior

Unit distributions are commonly used in probability and statistics to describe useful quantities with values between 0 and 1, such as proportions, probabilities, and percentages. Some unit distributions are defined in a natural analytical manner, and the others are derived through the transformation of an existing distribution defined in a greater domain. In this article, we introduce the unit gamma/Gompertz distribution, founded on the inverse-exponential scheme and the gamma/Gompertz distribution. The gamma/Gompertz distribution is known to be a very flexible three-parameter lifetime distribution, and we aim to transpose this flexibility to the unit interval. First, we check this aspect with the analytical behavior of the primary functions. It is shown that the probability density function can be increasing, decreasing, “increasing-decreasing” and “decreasing-increasing”, with pliant asymmetric properties. On the other hand, the hazard rate function has monotonically increasing, decreasing, or constant shapes. We complete the theoretical part with some propositions on stochastic ordering, moments, quantiles, and the reliability coefficient. Practically, to estimate the model parameters from unit data, the maximum likelihood method is used. We present some simulation results to evaluate this method. Two applications using real data sets, one on trade shares and the other on flood levels, demonstrate the importance of the new model when compared to other unit models.

scholarly journals Mass outflow of the X-ray emission line gas in NGC 4151

2020 ◽  
Vol 15 (S359) ◽  
pp. 131-135
Author(s):  
S. B. Kraemer ◽  
T. J. Turner ◽  
D. M. Crenshaw ◽  
H. R. Schmitt ◽  
M. Revalski ◽  
...  
Keyword(s):  
Emission Line ◽  
Total Mass ◽  
High Energy ◽  
Model Parameters ◽  
Zeroth Order ◽  
Space Telescope ◽  
X Ray ◽  
Ngc 4151 ◽  
Outflow Rate ◽  
Mass Outflow

AbstractWe have analyzed Chandra/High Energy Transmission Grating spectra of the X-ray emission line gas in the Seyfert galaxy NGC 4151. The zeroth-order spectral images show extended H- and He-like O and Ne, up to a distance r ˜ 200 pc from the nucleus. Using the 1st-order spectra, we measure an average line velocity ˜230 km s–1, suggesting significant outflow of X-ray gas. We generated Cloudy photoionization models to fit the 1st-order spectra; the fit required three distinct emission-line components. To estimate the total mass of ionized gas (M) and the mass outflow rates, we applied the model parameters to fit the zeroth-order emission-line profiles of Ne IX and Ne X. We determined an M ≍ 5.4 × 105Mʘ. Assuming the same kinematic profile as that for the [O III] gas, derived from our analysis of Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra, the peak X-ray mass outflow rate is approximately 1.8 Mʘ yr–1, at r ˜ 150 pc. The total mass and mass outflow rates are similar to those determined using [O III], implying that the X-ray gas is a major outflow component. However, unlike the optical outflows, the X-ray emitting mass outflow rate does not drop off at r > 100pc, which suggests that it may have a greater impact on the host galaxy.

Methylene. III. Gas phase reactions with 1-chloropropane

1969 ◽  
Vol 312 (1509) ◽  
pp. 141-161 ◽  
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Hydrogen Abstraction ◽  
The Other ◽  
Gas Phase Reactions ◽  
Other Hand ◽  
Chlorine Substituent ◽  
High Degree ◽  
Singlet Methylene

The work described in this and the following paper is a continuation of that in parts I and II, devoted to elucidation of the mechanism of the reactions of methylene with chloroalkanes, with particular reference to the reactivities of singlet and triplet methylene in abstraction and insertion processes. The products of the reaction between methylene, prepared by the photolysis of ketene, and 1-chloropropane have been identified and estimated and their dependence on reactant pressures, photolysing wavelength and presence of foreign gases (oxygen and carbon mon­oxide) has been investigated. Both insertion and abstraction mechanisms contribute significantly to the over-all reaction, insertion being relatively much more important than with chloroethane. This type of process appears to be confined to singlet methylene. If, as seems likely, there is no insertion into C—Cl bonds under our conditions (see part IV), insertion into C2—H and C3—H bonds occurs in statistical ratio, approximately. On the other hand, the chlorine substituent reduces the probability of insertion into C—H bonds in its vicinity. As in the chloroethane system, both species of methylene show a high degree of selectivity in their abstraction reactions. We find that k S Cl / k S H >7.7, k T Cl / k T H < 0.14, where the k ’s are rate constants for abstraction, and the super- and subscripts indicate the species of methylene and the type of atom abstracted, respectively. Triplet methylene is discriminating in hydrogen abstraction from 1-C 3 H 7 Cl, the overall rates for atoms attached to C1, C2, C3 being in the ratios 2.63:1:0.

INTRA-LEFT VENTRICULAR FLOW DISTRIBUTIONS IN DIASTOLIC AND SYSTOLIC PHASES, BASED ON ECHO VELOCITY FLOW MAPPING OF NORMAL SUBJECTS AND HEART FAILURE PATIENTS, TO CHARACTERIZE LEFT VENTRICULAR PERFORMANCE OUTCOMES OF HEART FAILURE

2012 ◽  
Vol 12 (05) ◽  
pp. 1240029 ◽  
Author(s):  
THU-THAO LE ◽  
RU-SAN TAN ◽  
FEIQIONG HUANG ◽  
LIANG ZHONG ◽  
SRIDHAR IDAPALAPATI ◽  
...  
Keyword(s):  
Heart Failure ◽  
Velocity Vector ◽  
Normal Subjects ◽  
Performance Outcomes ◽  
Left Ventricular ◽  
Inflow Rate ◽  
Flow Mapping ◽  
Velocity Flow ◽  
Outflow Rate ◽  
Blood Flow Patterns

Heart failure (HF), one of the most common diseases in the world, causes left ventricular dysfunction (LV) and high mortality. HF patients are stratified into two groups based on their LV ejection fraction (EF) — HF with normal EF (HFNEF) and with reduced EF (HFREF). EF is a commonly used measure of LV contractile performance. Despite preserved EF, a complex mixture of systolic and diastolic dysfunction and variable degrees of LV remodelling underlying HFNEF poses challenges to diagnose and provide pharmacological treatment for HFNEF. In recent years, the velocity flow mapping (VFM) technique has been developed to generate flow velocity vector fields by post-processing color Doppler echocardiographic (echo) images. We aim to obtain the intra-LV blood flow patterns for patients with HFNEF, HFREF, and normal subjects, in order to characterize the LV performance outcomes of normal subjects and HF patients. Two subjects from each group of HFNEF, HFREF, and normal underwent echo scans. Velocity vector distributions throughout the cardiac cycle were then analysed using the VFM technique. In each subject, the outflow rate during systole, inflow rate during diastole, as well as wall stress-based pressure-normalized contractility index, dσ*/dt max , were computed and compared among the groups. This study demonstrated the use of VFM to visualize LV blood flow patterns in HF patients and normal subjects. Different patterns of flow distributions were observed in these subjects. In HFREF patients, dσ*/dt max , the peak outflow rate and peak inflow rate during early filling were markedly reduced. In HFNEF patients, peak outflow rates were increased compared to those of normal subjects.

Direct Nucleation of Crystalline SiGe on Substrates by Reactive Thermal CVD with Si2H6 and GeF4

1997 ◽  
Vol 467 ◽  
Author(s):  
Fumio Yoshizawa ◽  
Kunihiro Shiota ◽  
Daisuke Inoue ◽  
Jun-ichi Hanna
Keyword(s):  
Growth Rate ◽  
Gas Phase ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Film Growth ◽  
Early Stage ◽  
Gaseous Mixture ◽  
The Other ◽  
Thermal Cvd ◽  
Initial Deposition

ABSTRACTPolycrystalline SiGe (poly-SiGe) film growth by reactive thermal CVD with a gaseous mixture of Si2H6 and GeF4 was investigated on various substrates such as Al,Cr, Pt, Si, ITO, ZnO and thermally grown SiO2.In Ge-rich film growth, SEM observation in the early stage of the film growth revealed that direct nucleation of crystallites took place on the substrates. The nucleation was governed by two different mechanisms: one was a heterogeneous nucleation on the surface and the other was a homogeneous nucleation in the gas phase. In the former case, the selective nucleation was observed at temperatures lower than 400°C on metal substrates and Si, where the activation of adsorbed GeF4 on the surface played a major role for the nuclei formation, leading to the selective film growth.On the other hand, the direct nucleation did not always take place in Si-rich film growth irrespective of the substrates and depended on the growth rate. In a growth rate of 3.6nm/min, the high crystallinity of poly-Si0.95Ge0.05in a 220nm-thick film was achieved at 450°C due to the no initial deposition of amorphous tissue on SiO2 substrates.

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