scholarly journals Simple scaling relations in geodynamics: the role of pressure in mantle convection and plume formation

2004 ◽  
Vol 49 (19) ◽  
pp. 2017 ◽  
Author(s):  
Anderson Don L.
Keyword(s):  
Mantle Convection ◽  
Scaling Relations ◽  
Simple Scaling

Supermassive Black Hole feedback in early type galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 119-125
Author(s):  
W. Forman ◽  
C. Jones ◽  
A. Bogdan ◽  
R. Kraft ◽  
E. Churazov ◽  
...  
Keyword(s):  
Dark Matter Halo ◽  
Scaling Relations ◽  
Radio Sources ◽  
Early Type ◽  
X Ray ◽  
Galaxy Groups ◽  
Sufficient Energy ◽  
The Galaxy ◽  
Simple Scaling ◽  
Halo Masses

AbstractOptically luminous early type galaxies host X-ray luminous, hot atmospheres. These hot atmospheres, which we refer to as coronae, undergo the same cooling and feedback processes as are commonly found in their more massive cousins, the gas rich atmospheres of galaxy groups and galaxy clusters. In particular, the hot coronae around galaxies radiatively cool and show cavities in X-ray images that are filled with relativistic plasma originating from jets powered by supermassive black holes (SMBH) at the galaxy centers. We discuss the SMBH feedback using an X-ray survey of early type galaxies carried out using Chandra X-ray Observatory observations. Early type galaxies with coronae very commonly have weak X-ray active nuclei and have associated radio sources. Based on the enthalpy of observed cavities in the coronae, there is sufficient energy to “balance” the observed radiative cooling. There are a very few remarkable examples of optically faint galaxies that are 1) unusually X-ray luminous, 2) have large dark matter halo masses, and 3) have large SMBHs (e.g., NGC4342 and NGC4291). These properties suggest that, in some galaxies, star formation may have been truncated at early times, breaking the simple scaling relations.

scholarly journals Breaking Simple Scaling Relations through Metal–Oxide Interactions: Understanding Room-Temperature Activation of Methane on M/CeO2 (M = Pt, Ni, or Co) Interfaces

2020 ◽  
Vol 11 (21) ◽  
pp. 9131-9137
Author(s):  
Pablo G. Lustemberg ◽  
Feng Zhang ◽  
Ramón A. Gutiérrez ◽  
Pedro J. Ramírez ◽  
Sanjaya D. Senanayake ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Room Temperature ◽  
Scaling Relations ◽  
Simple Scaling ◽  
Temperature Activation

scholarly journals Breaking Simple Scaling Relations Through Metal-Oxide Interactions: Understanding Room Temperature Activation of Methane on M-CeO2 (M= Pt, Ni or Co) Interfaces

2020 ◽  
Author(s):  
Pablo Lustemberg ◽  
Feng Zhang ◽  
Ramón A. Gutiérrez ◽  
Pedro J. Ramírez ◽  
Sanjaya D. Senanayake ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Ambient Pressure ◽  
Scaling Relations ◽  
Time Resolved ◽  
X Ray ◽  
Metal Support ◽  
Simple Scaling

The clean activation of methane at low temperatures remains an eminent challenge and a field of competitive research. In particular, on late transition metal surfaces such as Pt(111) or Ni(111), elevated temperatures are necessary to activate the hydrocarbon molecule, but a massive deposition of carbon makes the metal surface useless for catalytic activity. However, on very low-loaded M/CeO2 (M= Pt, Ni, or Co) surfaces, the dissociation of methane occurs at room temperature, which is unexpected considering simple linear scaling relationships. This intriguing phenomenon has been studied using a combination of experimental techniques (ambient-pressure X-ray photoelectron spectroscopy, time-resolved X-ray diffraction and X-ray absorption spectroscopy) and density functional theory-based calculations. The experimental and theoretical studies show that the size and morphology of the supported nanoparticles together with strong metal-support interactions are behind the deviations from the scaling relations. These findings point toward a possible strategy to circumvent scaling relations, producing active and stable catalysts which can be employed for methane activation and conversion. <br>

scholarly journals Seismic performance

2019 ◽  
Vol 622 ◽  
pp. A76 ◽  
Author(s):  
B. Mosser ◽  
E. Michel ◽  
R. Samadi ◽  
A. Miglio ◽  
G. R. Davies ◽  
...  
Keyword(s):  
Information Content ◽  
Seismic Performance ◽  
Scaling Relations ◽  
Fundamental Properties ◽  
Evolved Stars ◽  
Simple Scaling ◽  
Observational Noise ◽  
Stellar Properties ◽  
Seismic Index ◽  
Intrinsic Scatter

Context. Asteroseismology is a unique tool that can be used to study the interior of stars and hence deliver unique information for the studiy of stellar physics, stellar evolution, and Galactic archaeology. Aims. We aim to develop a simple model of the information content of asteroseismology and to characterize the ability and precision with which fundamental properties of stars can be estimated for different space missions. Methods. We defined and calibrated metrics of the seismic performance. The metrics, expressed by a seismic index ℰ defined by simple scaling relations, are calculated for an ensemble of stars. We studied the relations between the properties of mission observations, fundamental stellar properties, and the performance index. We also defined thresholds for asteroseismic detection and measurement of different stellar properties. Results. We find two regimes of asteroseismic performance: the first where the signal strength is dominated by stellar properties and not by observational noise; and the second where observational properties dominate. Typically, for evolved stars, stellar properties provide the dominant terms in estimating the information content, while main sequence stars fall in the regime where the observational properties, especially stellar magnitude, dominate. We estimate scaling relations to predict ℰ with an intrinsic scatter of around 21%. Incidentally, the metrics allow us to distinguish stars burning either hydrogen or helium. Conclusions. Our predictions will help identify the nature of the cohort of existing and future asteroseismic observations. In addition, the predicted performance for PLATO will help define optimal observing strategies for defined scientific goals.

Role of the lithosphere in mantle convection

1988 ◽  
Vol 93 (B9) ◽  
pp. 10451-10466 ◽  
Author(s):  
Geoffrey F. Davies
Keyword(s):  
Mantle Convection

scholarly journals Fast compression of magnetic flux inside an imploding cylinder driven by laser beams

1990 ◽  
Vol 8 (3) ◽  
pp. 477-484 ◽  
Author(s):  
W. H. Choe
Keyword(s):  
Magnetic Flux ◽  
Shell Model ◽  
Thin Shell ◽  
Pulse Generator ◽  
Laser Beams ◽  
Scaling Relations ◽  
Magnetic Pulse ◽  
Simple Scaling

A method for the compression of magnetic flux inside a cylindrical liner imploded by laser beams is analyzed using a thin shell model. Simple scaling relations are derived for a number of key parameters. The potential of this scheme, as a fast-rising magnetic pulse generator, is explored based on the scalings obtained.

Movement-related phasic muscle activation. I. Relations with temporal profile of movement

1990 ◽  
Vol 63 (3) ◽  
pp. 455-464 ◽  
Author(s):  
S. H. Brown ◽  
J. D. Cooke
Keyword(s):  
Muscle Activation ◽  
Temporal Structure ◽  
Temporal Properties ◽  
Human Arm ◽  
Acceleration And Deceleration ◽  
Simple Scaling ◽  
Temporal Structures ◽  
Movement Parameters ◽  
Temporal Profiles

1. The role of phasic muscle activation in determining the temporal properties of human arm movements was studied. The experiments show that subjects can modulate the triphasic electromyographic (EMG) pattern to produce movements of varied temporal structures. 2. Subjects performed horizontal forearm movements in which they varied movement accelerations and decelerations. All movements were of the same amplitude, duration, and peak velocity. A phase-plane (velocity vs. position) template of the desired movement was presented to the subject, who had to reproduce the template by appropriate movement of the forearm. 3. The ratio of the durations of acceleration to deceleration (termed the symmetry ratio, SR) was used as a measure of the temporal structure of the movements. Movements with SRs ranging from 0.4 (short acceleration-long deceleration) to 2.0 (long acceleration-short deceleration) were studied. 4. Subjects modulated the components of the triphasic EMG pattern to produce movements with different temporal profiles. As the SR was increased (increasing acceleration duration-decreasing deceleration duration), the following changes occurred: 1) the duration of the initial agonist burst (AG1) increased while its magnitude decreased; 2) the antagonist burst (ANT1) was progressively delayed relative to movement onset. ANT1 magnitude increased while its duration remained constant; and 3) the magnitude of the second agonist burst (AG2) increased and its duration decreased. 5. The triphasic EMG pattern can be modified to produce movements whose velocity profiles are not the same under simple scaling of duration or magnitude. It is concluded that previously described relations between components of the triphasic EMG pattern and movement parameters, such as amplitude, speed, and duration, are secondary to associated changes in their acceleration and deceleration characteristics.

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