scholarly journals Scanning geophysical hazards

2020 ◽  
Vol 51 (2) ◽  
pp. 14-16
Author(s):  
James Baker
Keyword(s):  
Complete Picture ◽  
Snow Avalanches ◽  
X Ray ◽  
Granular Physics ◽  
Fresh Insight

Granular physics, the study of how collections of macroscopic particles behave en masse, helps us to model geophysical hazards like snow avalanches and landslides. Before placing trust in any predictions, we need a complete picture of how opaque grains flow. X-ray technologies provide an unobtrusive means to see beyond the surface. Whereas classical tomography does not work for moving samples, new dynamic X-ray approaches can handle genuinely flowing regimes, offering fresh insight.

Composition of Alloy of Taurian Chersonesos Silver Coins

2021 ◽  
pp. 107-115
Author(s):  
Tatiana Smekalova ◽  
◽  
Natalia Demidenko ◽  
◽  
Keyword(s):  
Fluorescence Spectroscopy ◽  
Alloy Composition ◽  
The State ◽  
Controversial Issue ◽  
Complete Picture ◽  
X Ray

The paper offers the first complete picture of the changing in the alloy composition of silver coins of the ancient Tauric Chersonesos. Coins from two largest collections were examined: the State Hermitage and the State Historical and Archaeological Museum-Reserve “Tauric Chersonesos”. In total, about 190 Chersonesean silver coins were studied by X-ray fluorescence spectroscopy. The results obtained made it possible to determine the stages of functioning of fool metallic value silver coins and to reveal the time of their transformation into conventional or credit coins. This happened at the end of the autonomous period of Chersonesos, after which silver coins were no longer minted in Chersonesos, with the exception of an episodic and controversial issue during the period of the influence of Mithridates VI.

scholarly journals A new methodology exploring the record of snow avalanches in lake sediments

2016 ◽  
Author(s):  
Laurent Fouinat ◽  
Pierre Sabatier ◽  
Jérôme Poulenard ◽  
Jean-Louis Reyss ◽  
Xavier Montet ◽  
...  
Keyword(s):  
Organic Matter ◽  
Global Change ◽  
Lake Sediments ◽  
Sediment Cores ◽  
Ct Scanning ◽  
Ct Scans ◽  
Snow Avalanches ◽  
X Ray ◽  
Steep Slopes ◽  
Non Destructive

Abstract. In recent years, wet avalanche deposits have become a subject of increasing concern in a context of both global change and winter mountain tourism activities. This study focuses on the use of a new methodology based on CT scans to identify snow avalanche deposits in lake sediment. Here, we study the mid-elevation Lake Lauvitel system (western French Alps), which features steep slopes and avalanche corridors. CT scanning is a fast, non-destructive method based on X-ray technology and allows the identification of elements with different densities. We applied this method to sediment cores, leading to the 3D identification of the dense rocks and organic matter macroremains that characterize wet avalanches. A total of eight periods of higher avalanche activity are identified since AD 1880 at the site. This new methodology is suitable for avalanche deposit reconstruction and may be applicable more widely in paleolimnological studies.

Resilience and Redundance: Resource Networks and the Neolithic Chert Economy at Çatalhöyük, Turkey

2015 ◽  
Vol 18 (3) ◽  
pp. 402-428 ◽  
Author(s):  
Adam Joseph Nazaroff ◽  
Adnan Baysal ◽  
Yahya Çiftçi ◽  
Keith Prufer
Keyword(s):  
Middle East ◽  
Fluorescence Analysis ◽  
Complete Picture ◽  
Social Fabric ◽  
X Ray ◽  
The Social ◽  
Social Environmental ◽  
Resource Networks ◽  
Regional Diversification

The polycentric nature of Neolithic developments in the Middle East has prompted several discussions related to the processes driving regional diversification in the emergence of agglomerate societies. Archaeologists have recognized how diverse social, environmental, and material landscapes shaped various communities, resulting in a heterogenous Neolithic world. In this paper, we use portable x-ray fluorescence analysis to determine the use of different chert resources at the site of Çatalhöyük, Turkey, and question how their consumption affected, and was affected by, different social and material practices enacted within the community. We adopt a network perspective to examine the range of behaviours that consumed particular resources, and trace how alterations in these networks impacted the social fabric of Çatalhöyük. Ultimately, we conclude that different investments involved in the consumption of each resource either promoted or restricted their use through time. A more complete picture of Neolithic life, we suggest, takes note of the varied relationships that communities developed with nearby social and environmental landscapes, including nuances in the ways in which resources were incorporated into different facets of each community.

Electron Microscopy (TEM) and X-ray Spectromicroscopy (STXM) of PP/MMT/PP-g-MA and PP/MMT/SEBS Nanocomposites

2010 ◽  
Vol 1257 ◽  
Author(s):  
Zulima Martin ◽  
M. Angeles Gomez ◽  
Ignacio Jimenez
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Complete Picture ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractHere we present a study on the polypropylene/montmorillonite interaction based on x-ray diffraction, transmission electron microscopy (TEM) and scanning transmission x-ray microscopy (STXM) measurements, which provides a complete picture of the intercalation and exfoliation processes taking place.

The secondary maxima in black hole X-ray nova light curves - Clues toward a complete picture

1993 ◽  
Vol 408 ◽  
pp. L5 ◽  
Author(s):  
Wan Chen ◽  
Mario Livio ◽  
Neil Gehrels
Keyword(s):  
Black Hole ◽  
Light Curves ◽  
Complete Picture ◽  
X Ray

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

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