The Current Status in the Modelling of Stellar Atmospheres

2003 ◽  
Vol 210 ◽  
pp. 3-18 ◽  
Author(s):  
Bengt Gustafsson
Keyword(s):  
Recent Progress ◽  
Classification Scheme ◽  
Model Atmosphere ◽  
Stellar Atmospheres ◽  
Current Status ◽  
Contemporary Research ◽  
Quality Classification ◽  
Different Types

The old question whether models of stellar atmospheres are wrong, adequate, or even overelaborated, is discussed with a number of examples from contemporary research as a background. A simple quality classification scheme for models of different types is presented. It is concluded that, in spite of rapid recent progress, we are far from having fully satisfactory theoretical representations of stellar atmospheres. Reasons for continuing the efforts to reach a higher degree of physical consistency in model atmosphere work are discussed.

scholarly journals Fundamental Parameters and Models of Stellar Atmospheres

1985 ◽  
Vol 111 ◽  
pp. 303-329
Author(s):  
Bengt Gustafsson ◽  
Uffe Graae-Jørgensen
Keyword(s):  
Model Atmosphere ◽  
Stellar Atmospheres ◽  
Chemical Compositions ◽  
Fundamental Parameters ◽  
Different Types ◽  
Effective Temperatures

The use of photometric and spectroscopic criteria, calibrated by model-atmosphere calculations, for determining effective temperatures, surface gravities and chemical compositions of stars is illustrated and commented on. The accuracy that can be obtained today in such calibrations is discussed, as well as possible ways of improving this accuracy further for different types of stars.

scholarly journals Recent progress in materials development for CO2 conversion: issues and challenges

2021 ◽  
Author(s):  
Sourav Ghosh ◽  
Arindam Modak ◽  
Arnab Samanta ◽  
Kanika Kole ◽  
Subhra Jana
Keyword(s):  
Recent Progress ◽  
Value Added ◽  
Advanced Materials ◽  
Current Status ◽  
Co2 Conversion ◽  
Technical Feasibility ◽  
Materials Development

A comprehensive and critical in-depth discussion on the development and prospect of several advanced materials for conversion of CO2 to value added chemicals is provided, together with their current status, technical feasibility and future opportunities.

Transforming lanthanide and actinide chemistry with nanoparticles

Nanoscale ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 1339-1348 ◽  
Author(s):  
Roger M. Pallares ◽  
Rebecca J. Abergel
Keyword(s):  
Recent Progress ◽  
Actinide Chemistry ◽  
Different Types

This minireview summarizes and discusses recent progress on the use of nanoparticles in lanthanide and actinide chemistry. We examine different types of nanoparticles and critically analyze their performance in a comparative mode.

scholarly journals What is a social pattern? Rethinking a central social science term

2021 ◽  
Author(s):  
Hernan Mondani ◽  
Richard Swedberg
Keyword(s):  
Social Science ◽  
Social Action ◽  
Current Status ◽  
Cultural Patterns ◽  
Social Patterns ◽  
Different Types ◽  
Central Social

AbstractThe main aim of this article is to start a discussion of social pattern, a term that is commonly used in sociology but not specified or defined. The key question can be phrased as follows: Is it possible to transform the notion of social pattern from its current status in sociology as a proto-concept into a fully worked out concept? And if so, how can this be done? To provide material for the discussion we begin by introducing a few different types of patterns that are currently being used (patterns in nature, cultural patterns, statistical patterns, and computationally generated patterns). This is followed by a suggestion for what a strictly sociological concept of social pattern may look like. A useful and theoretically solid concept of social pattern can in our view be constructed by basing it on Weber’s concept of social action. This means that both the behavior of the actors and the meaning these invest their behavior with must be taken into account. The article ends with a brief discussion of how to use the concept of social patterns in an effective way and what may endanger such a use.

scholarly journals What 100 Years of Typing Research Can Tell Us

2019 ◽  
Author(s):  
Motonori Yamaguchi
Keyword(s):  
20Th Century ◽  
Practical Importance ◽  
Computer Interface ◽  
Current Status ◽  
Early 20Th Century ◽  
Dominant Form ◽  
Complex Skills ◽  
Different Types ◽  
The Common ◽  
The Right

The need of typewriting skill is ever increasing in our lives. The prevalence of personal computers and mobile devices has transformed the way people communicate with each other. Although many different types of human interfaces have been introduced over the decades, the dominant form of computer interface remains to be that of typing on a keyboard. [...] Whilst typing has become one of the common everyday skills within the last two decades, experimental psychologists have been studying it as a research subject for more than a hundred years. [...] Apart from its practical importance in the modern lifestyle, the act of typing involves the right amount of complexity as well as well-defined and measurable actions. These features of typewriting makes it an ideal testbed to gain our understanding of the control and acquisition of complex skills. This review article first presents a brief overview of the classic studies of typewriting skill in the early 20th century, discusses the developments that took place after the mid-20th century, and concludes with the current status and issues that remain for future investigations in the 21st century.

scholarly journals Drug Discovery against Acanthamoeba Infections: Present Knowledge and Unmet Needs

Pathogens ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 405 ◽  
Author(s):  
Hany M. Elsheikha ◽  
Ruqaiyyah Siddiqui ◽  
Naveed Ahmed Khan
Keyword(s):  
Recent Progress ◽  
Unmet Needs ◽  
Drug Repurposing ◽  
Present Knowledge ◽  
Current Status ◽  
Therapeutic Landscape ◽  
Pharmacological Targets ◽  
Health Complications ◽  
Interfering Rna ◽  
Made In

Although major strides have been made in developing and testing various anti-acanthamoebic drugs, recurrent infections, inadequate treatment outcomes, health complications, and side effects associated with the use of currently available drugs necessitate the development of more effective and safe therapeutic regimens. For any new anti-acanthamoebic drugs to be more effective, they must have either superior potency and safety or at least comparable potency and an improved safety profile compared to the existing drugs. The development of the so-called ‘next-generation’ anti-acanthamoebic agents to address this challenge is an active area of research. Here, we review the current status of anti-acanthamoebic drugs and discuss recent progress in identifying novel pharmacological targets and new approaches, such as drug repurposing, development of small interfering RNA (siRNA)-based therapies and testing natural products and their derivatives. Some of the discussed approaches have the potential to change the therapeutic landscape of Acanthamoeba infections.

A Classification Scheme for Interpretive Research in Information Systems

2011 ◽  
pp. 218-239 ◽  
Author(s):  
Heinz K. Klein ◽  
Michael D. Myers
Keyword(s):  
Information Systems ◽  
Division Of Labor ◽  
Classification Scheme ◽  
Research Priorities ◽  
Field Studies ◽  
Research Articles ◽  
Interpretive Research ◽  
Philosophical Foundations ◽  
Different Types ◽  
Explicit Consideration

Given the increase in the number of interpretive research articles being published in IS today, we believe it is timely to develop and explain a classification scheme of the literature. Such a classification scheme draws attention to the tremendous variety and breadth of interpretive research today, from the most abstract and general philosophical foundations to the most in-depth, detailed field studies. The explicit consideration of different types may contribute to a more effective division of labor among scholars with different research interests. It should also help interpretive researchers to better focus their work and to identify their research priorities.

scholarly journals Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours

2018 ◽  
Vol 613 ◽  
pp. A24 ◽  
Author(s):  
A. Kučinskas ◽  
J. Klevas ◽  
H.-G. Ludwig ◽  
P. Bonifacio ◽  
M. Steffen ◽  
...  
Keyword(s):  
Main Sequence ◽  
Broad Band ◽  
Stellar Atmospheres ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Different Types ◽  
Convective Motions ◽  
Effective Temperatures ◽  
Red Giant ◽  
Colour Indices

Aims. We studied the influence of convection on the spectral energy distributions (SEDs), photometric magnitudes, and colour indices of different types of stars across the H–R diagram. Methods. The 3D hydrodynamical CO5BOLD, averaged ⟨3D⟩, and 1D hydrostatic LHD model atmospheres were used to compute SEDs of stars on the main sequence (MS), main sequence turn-off (TO), subgiant branch (SGB), and red giant branch (RGB), in each case at two different effective temperatures and two metallicities, [M∕H] = 0.0 and − 2.0. Using the obtained SEDs, we calculated photometric magnitudes and colour indices in the broad-band Johnson-Cousins UBVRI and 2MASS JHKs, and the medium-band Strömgren uvby photometric systems. Results. The 3D–1D differences in photometric magnitudes and colour indices are small in both photometric systems and typically do not exceed ± 0.03 mag. Only in the case of the coolest giants located on the upper RGB are the differences in the U and u bands able reach ≈−0.2 mag at [M∕H] = 0.0 and ≈−0.1 mag at [M∕H] = −2.0. Generally, the 3D–1D differences are largest in the blue-UV part of the spectrum and decrease towards longer wavelengths. They are also sensitive to the effective temperature and are significantly smaller in hotter stars. Metallicity also plays a role and leads to slightly larger 3D–1D differences at [M∕H] = 0.0. All these patterns are caused by a complex interplay between the radiation field, opacities, and horizontal temperature fluctuations that occur due to convective motions in stellar atmospheres. Although small, the 3D–1D differences in the magnitudes and colour indices are nevertheless comparable to or larger than typical photometric uncertainties and may therefore cause non-negligible systematic differences in the estimated effective temperatures.

Material Characteristics Evaluation of Existing Pre-Stressed Concrete Railroad Ties After Service Period

2018 ◽  
Author(s):  
Aref Shafiei Dastgerdi ◽  
Kyle Riding ◽  
Robert J. Peterman ◽  
B. Terry Beck
Keyword(s):  
Service Life ◽  
High Speed ◽  
Current Status ◽  
Polished Surface ◽  
Material Characteristic ◽  
Freeze Thaw ◽  
Material Characteristics ◽  
Void System ◽  
Different Types ◽  
Air Void

As an important element in track, pre-stressed concrete railroad ties in the high-speed rail industry must meet the safety and performance specifications of high-speed trains. Systematic destructive and non-destructive evaluation of existing concrete ties can lead to a better understanding of the effect of prestressed concrete tie material design on performance and failure within their service life. It has been evident that environmental and climate conditions also have a significant impact on concrete railroad ties, causing various forms of deterioration such as abrasion and freeze-thaw damage. Understanding of the material characteristics that cause failure in different types of existing concrete railroad ties taken from different places is the main focus of this paper. Observing the current status and damages of railroad ties taken from track might give a correlation between the material characteristic and type of distress and cracking seen. Although it has been seen by previous works that effective factors such as air void system and material composition directly affect the performance of concrete ties such as freeze-thaw, material evaluation of existing ties after service life has not been addressed in previous publications. In this research, the authors have investigated the material characteristic such as aggregate and air-void system of existing pre-stressed concrete railroad ties taken from track. However, compressive and splitting tensile strength and fractured surface of samples cored from the ties were acquired. In order to obtain the strength of concrete materials of existing ties, six samples were cored from six different types of ties taken from tracks across the U.S., according to ASTM C42-16, and tested using ASTM C39 and ASTM C496 methods. However, the concrete air-void system (ASTM C457) was measured on saw-cut samples extracted from the ties to evaluate the influence air content and distribution on mechanical properties of the ties. Regarding the history and service life condition of the ties, it seems that material properties of the ties effectively alter the performance of the ties. Aggregate sources used at each location may have different properties such as texture, angularity, and mineralogy, contributing either propagation or resistance in splitting cracking in concrete. Furthermore, the polished surface of samples extracted from the ties show the uniformity and air void system in some ties which demonstrate their superiority in terms of resistance to freeze-thaw damage. Considering the results of this research, comprehensive evaluation of material characteristics might give a better view of existing concrete railroad ties situation, providing a worthwhile background for future tie design considerations.

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