scholarly journals The Cepheid Instability “Wedge“

1993 ◽  
Vol 139 ◽  
pp. 307-307
Author(s):  
Siobahn M. Morgan
Keyword(s):  
Recent Work ◽  
Observational Data ◽  
Instability Region ◽  
Mixing Length ◽  
Interesting Structure

For the most part it had been assumed that the red and the blue edges of the Cepheid Instability region were parallel. However, previous work by Pel and Lub (1978) and recent work by Fernie (1990) seems to reveal a rather interesting structure to the shape of the Cepheid Instability region. Figure 1 shows the shape defined using the data from Fernie (1990) and the observational data of Gieren (1989). It is apparent that the edges defined by the distribution of these points are not parallel.I have calculated a series of pulsation models that included varying values of the mixing length to try and produce a distribution of Cepheids as seen in Figure 1. Calculations were done using the methods outlined by Castor (1971) with a Linear Non Adiabatic pulsation code to determine the characteristics for a given model.

scholarly journals Turbulent Convection: A New Model

1991 ◽  
Vol 130 ◽  
pp. 27-32
Author(s):  
V. M. Canuto
Keyword(s):  
Observational Data ◽  
Turbulent Convection ◽  
Mixing Length ◽  
Convective Flux ◽  
New Model ◽  
Mixing Length Theory

AbstractWe use the latest models of turbulence to compute a new expression for the turbulent convective flux, Fc. The new values of Fc are up to ten times larger than those given by the mixing length theory, MLT. Astrophysical considerations indicate that the new model fares better with observational data than the MLT.

scholarly journals Boundaries of the δ Scuti Instability Region

2000 ◽  
Vol 176 ◽  
pp. 443-443
Author(s):  
Alexei A. Pamyatnykh
Keyword(s):  
Equation Of State ◽  
Observational Data ◽  
Main Sequence ◽  
Instability Region ◽  
Instability Strip

With new data on stellar opacity and equation of state, we computed the theoretical blue edges of the classical instability strip in the vicinity of the main sequence. The results were compared with observational data on δ Scuti variables using various diagrams (HR, log g – log Teff, Mv – (b – y)0 and so on). An example of these diagrams is shown in Fig. 1. Detailed results can be found in Pamyatnykh (2000).

scholarly journals CONSISTENCY TEST AND CONSTRAINT OF QUINTESSENCE

2011 ◽  
Vol 01 ◽  
pp. 240-244
Author(s):  
CHIEN-WEN CHEN ◽  
JE-AN GU ◽  
PISIN CHEN
Keyword(s):  
Dark Energy ◽  
Confidence Interval ◽  
Recent Work ◽  
Observational Data ◽  
Power Law ◽  
Confidence Level ◽  
Characteristic Parameter ◽  
Exponential Potential ◽  
Consistency Test

In this paper we highlight our recent work in arXiv:0803.4504. In that work, we proposed a new consistency test of quintessence models for dark energy. Our test gave a simple and direct signature if certain category of quintessence models was not consistent with the observational data. For a category that passed the test, we further constrained its characteristic parameter. Specifically, we found that the exponential potential was ruled out at the 95% confidence level and the power-law potential was ruled out at the 68% confidence level based on the current observational data. We also found that the confidence interval of the index of the power-law potential was between -2 and 0 at the 95% confidence level.

scholarly journals Overview of Grain Models

2000 ◽  
Vol 197 ◽  
pp. 317-330 ◽  
Author(s):  
Adolf N. Witt
Keyword(s):  
Chemical Composition ◽  
Size Distribution ◽  
Recent Work ◽  
Observational Data ◽  
Current Literature ◽  
Observational Constraints ◽  
Interstellar Grains ◽  
Self Consistent ◽  
Consistent Manner ◽  
Detailed Chemical

The properties of interstellar grains can now be defined by a rapidly growing wealth of observational data. We rely upon models to combine these data with unobserved properties such as the size distribution of grains, their structure and shape, and their detailed chemical composition, in a self-consistent manner. I will review the observational constraints which define the boundaries for possible models and will then summarize the features of the three quasi-comprehensive grain models most commonly referred to in the current literature. I will conclude by discussing recent work dealing with single aspects of interstellar grains and the phenomena attributed to them.

scholarly journals Flagpoles anyone? Causal and explanatory asymmetries

2020 ◽  
Author(s):  
James Woodward
Keyword(s):  
Machine Learning ◽  
Recent Work ◽  
Observational Data ◽  
Causal Explanation ◽  
Causal Direction

This paper discusses some procedures developed in recent work in machine learning for inferring causal direction from observational data. The role of independence and invariance assumptions is emphasized. Several familiar examples including Hempel’s flagpole problem are explored in the light of these ideas. The framework is then applied to problems having to do with explanatory direction in non-causal explanation.

scholarly journals Mixing in the SMC Stars: Implication for Cepheids

2000 ◽  
Vol 176 ◽  
pp. 381-382
Author(s):  
D. Cordier ◽  
T. Lejeune ◽  
Y. Lebreton ◽  
M.-J. Goupil
Keyword(s):  
Chemical Composition ◽  
Observational Data ◽  
Main Sequence ◽  
Observational Constraints ◽  
Evolutionary Models ◽  
Mixing Length ◽  
Instability Strip ◽  
Mixing Parameters ◽  
Low Metallicity ◽  
Red Giant

AbstractWe compare the recent OGLE 2 data of stars in the Small Magellanic Cloud (SMC) with stellar evolutionary models of low metallicity computed with the updated and numerically accurate code CESAM. The conversion between theoretical and observational data has been carefully done using the BaSel Library. This enables us to derive new observational constraints at SMC chemical composition: on the overshooting parameter αover during the main sequence, and on the mixing-length parameter αMLT for the red giant branch. The occurrence of an instability strip-crossing episode is strongly related to these mixing parameters.

Martyrdom, collective memory, and the contested penal authority of racial state institutions

2020 ◽  
pp. 146247452095012
Author(s):  
Bonar Buffam
Keyword(s):  
Collective Memory ◽  
Recent Work ◽  
Observational Data ◽  
British Empire ◽  
Nation State ◽  
Immigration Enforcement ◽  
Intelligence Gathering ◽  
State Institutions ◽  
Temporal Parameters ◽  
Canadian Immigration

Recent work in postcolonial and border criminologies has called for more extensive consideration of the complex temporal and geographic dimensions of penal authority. This article explicates new dimensions of the modern state’s penal authority by analyzing the execution and remembrance of Mewa Singh, a Sikh anticolonial activist convicted of killing Canadian immigration agent William C Hopkinson in Vancouver in 1914. Because Hopkinson was embedded in racial immigration enforcement against Indian populations as well as intelligence gathering about anticolonial activities, his death galvanized fields of penal authority that spanned the imperatives of the Canadian nation-state and the British Empire. Using archival and observational data, this article tracks how the significance of Mewa’s execution has been articulated through these penal fields as well as through recent practices of memorialization undertaken by local Sikh and Indian communities. Insofar as these mnemonic practices frame Mewa’s death as a sacrifice necessitated by state racism, my analysis illuminates the complex temporal parameters of penal fields of authority as well as the manner in which they are conditioned by racial borders and boundaries.

scholarly journals How Coach Educators Deliver Formal Coach Education: A Full Range Leadership Perspective

2021 ◽  
Vol 8 (1) ◽  
pp. 23-33 ◽  
Author(s):  
Paul Garner ◽  
Jennifer Turnnidge ◽  
Will Roberts ◽  
Jean Côté
Keyword(s):  
Transformational Leadership ◽  
Recent Work ◽  
Observational Data ◽  
Full Range ◽  
Assessment System ◽  
Alpine Skiing ◽  
Leadership Assessment ◽  
Coach Education ◽  
Coach Leadership ◽  
Full Range Leadership

While recent work recognizes a need for coach education to place greater emphasis on interpersonal knowledge when developing coaching expertise, it is our position that coach educators (CEs) must follow a similar trajectory in embracing the interpersonal knowledge requisite of their role and move beyond a reliance on content and professional knowledge in order to shape their delivery. To better understand CEs’ behaviors, the authors observed four experienced CEs in Alpine skiing, using an adapted version of the Coach Leadership Assessment System during delivery of a coach education and assessment course. The authors also interviewed CEs to further elucidate the observational data. The findings suggest the benefit of transactional approaches to leadership during assessment when set against the backdrop of an environment driven by intentions consistent with transformational leadership. Furthermore, we call for a greater appreciation of context when imagining CEs’ behaviors that align with effective practice.

Midlatitude Eddies, Storm-Track Diffusivity, and Poleward Moisture Transport in Warm Climates

2012 ◽  
Vol 69 (11) ◽  
pp. 3237-3250 ◽  
Author(s):  
Rodrigo Caballero ◽  
John Hanley
Keyword(s):  
High Temperature ◽  
Recent Work ◽  
Moisture Transport ◽  
Elevated Temperatures ◽  
Storm Track ◽  
Temperature Decrease ◽  
Mixing Length ◽  
Community Atmosphere Model ◽  
Or Organization ◽  
Nonmonotonic Behavior

Abstract Recent work using both simplified and comprehensive GCMs has shown that poleward moisture transport across midlatitudes follows Clausius–Clapeyron scaling at temperatures close to modern, but that it reaches a maximum at sufficiently elevated temperatures and then decreases with further warming. This study explores the reasons for this nonmonotonic behavior using a sequence of NCAR Community Atmosphere Model, version 3 (CAM3) simulations in an aquaplanet configuration spanning a broad range of climates. No significant change is found in the scale, structure, or organization of midlatitude eddies across these simulations. Instead, the high-temperature decrease in poleward moisture transport is attributed to the combined effect of decreasing eddy velocities and contracting mixing lengths. The contraction in mixing length is, in turn, a consequence of the decreasing eddy velocities in combination with constant eddy decorrelation time scales.

Current status of special planetary and lunar theories and ephemerides

1966 ◽  
Vol 25 ◽  
pp. 266-267
Author(s):  
R. L. Duncombe
Keyword(s):  
Observational Data ◽  
Current Status ◽  
Numerical Errors

An examination of some specialized lunar and planetary ephemerides has revealed inconsistencies in the adopted planetary masses, the presence of non-gravitational terms, and some outright numerical errors. They should be considered of temporary usefulness only, subject to subsequent amendment as required for the interpretation of observational data.

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