scholarly journals The Tharsis mantle source of depleted shergottites revealed by 90 million impact craters

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
A. Lagain ◽  
G. K. Benedix ◽  
K. Servis ◽  
D. Baratoux ◽  
L. S. Doucet ◽  
...  
Keyword(s):  
Thermal Anomaly ◽  
Detection Algorithm ◽  
Impact Craters ◽  
Early History ◽  
Volcanic Province ◽  
Crater Detection ◽  
Depleted Mantle ◽  
History Of ◽  
Secondary Crater ◽  
The Impact

AbstractThe only martian rock samples on Earth are meteorites ejected from the surface of Mars by asteroid impacts. The locations and geological contexts of the launch sites are currently unknown. Determining the impact locations is essential to unravel the relations between the evolution of the martian interior and its surface. Here we adapt a Crater Detection Algorithm that compile a database of 90 million impact craters, allowing to determine the potential launch position of these meteorites through the observation of secondary crater fields. We show that Tooting and 09-000015 craters, both located in the Tharsis volcanic province, are the most likely source of the depleted shergottites ejected 1.1 million year ago. This implies that a major thermal anomaly deeply rooted in the mantle under Tharsis was active over most of the geological history of the planet, and has sampled a depleted mantle, that has retained until recently geochemical signatures of Mars’ early history.

The Film World’s Cooperative Store: Institutions and Films of the 1930s and 1940s

2018 ◽  
Author(s):  
C. Claire Thomson
Keyword(s):  
World War Ii ◽  
Meat Products ◽  
Public Information ◽  
Early History ◽  
World War ◽  
International Context ◽  
German Occupation ◽  
History Of ◽  
The Uk ◽  
The Impact

This chapter traces the early history of state-sponsored informational filmmaking in Denmark, emphasising its organisation as a ‘cooperative’ of organisations and government agencies. After an account of the establishment and early development of the agency Dansk Kulturfilm in the 1930s, the chapter considers two of its earliest productions, both process films documenting the manufacture of bricks and meat products. The broader context of documentary in Denmark is fleshed out with an account of the production and reception of Poul Henningsen’s seminal film Danmark (1935), and the international context is accounted for with an overview of the development of state-supported filmmaking in the UK, Italy and Germany. Developments in the funding and output of Dansk Kulturfilm up to World War II are outlined, followed by an account of the impact of the German Occupation of Denmark on domestic informational film. The establishment of the Danish Government Film Committee or Ministeriernes Filmudvalg kick-started aprofessionalisation of state-sponsored filmmaking, and two wartime public information films are briefly analysed as examples of its early output. The chapter concludes with an account of the relations between the Danish Resistance and an emerging generation of documentarists.

From koine to standard: the early modern origin of a key linguistic term

2021 ◽  
Vol 7 (2) ◽  
pp. 283-302
Author(s):  
Raf Van Rooy
Keyword(s):  
Seventeenth Century ◽  
Western Europe ◽  
Early History ◽  
John Dryden ◽  
Common Language ◽  
Regional Dialects ◽  
Language Studies ◽  
Linguistic Term ◽  
History Of ◽  
The Impact

Abstract In this paper, I explore the early history of the word standard as a linguistic term, arguing that it came to compete with the designation common language in the seventeenth century. The latter phrase was, in turn, formed by ideas on the Greek koine during the Renaissance and appears to have been the first widely used collocation referring to a standard language-like entity. In order to sketch this evolution, I first discuss premodern ideas on the koine. Then, I attempt to outline how the intuitive comparison of the koine with vernacular norms that were being increasingly regulated resulted in the development of the concept of common language, termed lingua communis in Latin (a calque of Greek hē koinḕ diálektos), in the sixteenth century. This phrase highlighted the communicative functionality of the vernaculars, which were being codified in grammars and dictionaries. Scholars contrasted these common languages with regional dialects, which had a limited reach in terms of communication. This distinction received a social and evaluative connotation during the seventeenth century, which created a need for terminological alternatives; an increasingly popular option competing with common language was standard, which was variously combined with language and tongue by English authors from about 1650 onwards, especially in Protestant circles, where the vernaculars tended to play a more prominent role than in Catholic areas. Of major importance for this evolution was the work and linguistic usage of the poet John Dryden (1631–1700). This essay uncovers the early history of standard as a key linguistic term, while also presenting a case study which shows the impact of the rediscovery of the Greek heritage on language studies in Western Europe, especially through the term common language.

scholarly journals Candidates for multiple impact craters: popigai and chicxulub as seen by EGM08, a global 5'×5' gravitational model

2010 ◽  
Vol 2 (1) ◽  
pp. 69-103 ◽  
Author(s):  
J. Klokočník ◽  
J. Kostelecký ◽  
I. Pešek ◽  
P. Novák ◽  
C. A. Wagner ◽  
...  
Keyword(s):  
High Spatial Resolution ◽  
Impact Craters ◽  
Stokes Parameters ◽  
Disturbing Potential ◽  
Gravitational Model ◽  
Secondary Crater ◽  
Complete Set ◽  
Multiple Impact ◽  
The Impact ◽  
Main Crater

Abstract. In 2008 the new Earth Gravitational Model (EGM08) was released. It contains a complete set of spherical harmonic coefficients of the Earth's gravitational potential (Stokes parameters) to degree 2190 and order 2159 that can be used for evaluation of various potential quantities with both the unprecedented accuracy and high spatial resolution. Two such quantities, the gravity anomaly and second-order radial derivative of the disturbing potential, were computed over selected areas with known impact craters. The displays of these derivatives for two such sites clearly show not only the strong circular-like features known to be associated with them but also other symmetrical structures which appear to make them multiple impact sites. At Popigai, Siberia, the secondary circular features fall in a line from the primary in the SE direction. At Chicxulub, Yucatán, there appears to be one secondary crater close to the primary in the NE direction, as well as possibly others in the vicinity of the main crater. Gravity information alone is not proof of the impact craters but it is useful in identifying candidate sites for further study, for future examination by geologists and geophysicists.

scholarly journals Blockchain: Capabilities, Economic Viability, and the Socio-Technical Environment

2020 ◽  
Author(s):  
Nils Braun-Dubler ◽  
Hans-Peter Gier ◽  
Tetiana Bulatnikova ◽  
Manuel Langhart ◽  
Manuela Merki ◽  
...  
Keyword(s):  
Public Spaces ◽  
Early History ◽  
Economic Viability ◽  
Economic Potential ◽  
Key Technology ◽  
The Social ◽  
Real World Applications ◽  
History Of ◽  
History Of Information ◽  
The Impact

Blockchain is widely considered a new key technology. The Foundation for Technology Assessment (TA-SWISS) has proposed a comprehensive assessment of blockchain technologies. With this publication, TA-SWISS provides the much-needed social contextualisation of blockchain. The first, more technical part of the study takes an in-depth look at how blockchain functions and examines the economic potential of this technology. By analysing multiple real-world applications, the study sheds light on where the blockchain has advantages over traditional applications and where existing technologies continue to be the better solution. The second part of the study examines how blockchain became mainstream. It explores the origins of blockchain in the early history of information technology and computer networks. The study also reveals the impact blockchain has on industrial and public spaces. Finally, it discusses the social implications and challenges of blockchain against the background of a new socio-technical environment.

Reading Culture and Reading in 19th-Century Australia

2018 ◽  
Author(s):  
Susan K. Martin
Keyword(s):  
19Th Century ◽  
Early History ◽  
Reading Practices ◽  
Trade Routes ◽  
Publication Patterns ◽  
History Of ◽  
Reading Patterns ◽  
Reading Culture ◽  
Distance Travel ◽  
The Impact

Reading practices and tastes were transported to colonial Australia along with European colonists. Access to and circulation of books and newspapers in the colonies were subject to the vagaries of distance, travel, and transport, and these had a concomitant impact on reading patterns and access, as well as on the development of local writing and publishing. Trade routes, and the disjunction of inland versus sea routes, may have had some influence on localized reading and distribution. The early history of libraries and booksellers in the Australian colonies, publication patterns, and marketing give clues to reading patterns. Examining the reading accounts and movements of individual readers, and individual texts, provides further detail and context to the environment and situatedness of reading in the Australian colonies, as well as the impact of transport as an idea, and an influence on texts and reading.

Automatic crater detection over the Jezero crater area from HiRISE imagery

2020 ◽  
Author(s):  
Konstantinos Servis ◽  
Anthony Lagain ◽  
Gretchen Benedix ◽  
David Flannery ◽  
Chris Norman ◽  
...  
Keyword(s):  
Detection Rate ◽  
False Negative ◽  
Detection Algorithm ◽  
Impact Craters ◽  
Reference Points ◽  
Training Dataset ◽  
False Detection ◽  
Planetary Scale ◽  
Area Of Interest ◽  
Crater Detection

<p>Impact craters are used to determine the ages of planetary surfaces. Absolute dating of meteorites or in situ geochronology provide a few essential reference points, but these techniques are rare and not yet applicable at the planetary scale. Therefore, impact crater counting techniques will remain the major tool to decipher planetary surface history. This approach requires a tedious mapping and morphological inspection of a large number of circular features to distinguish true and primary impact craters. The most complete database of Martian craters includes a catalog of more than 384,000 impact structures larger than 1 km in diameter. This database is considered to be complete for this diameter range. A requirement to determine young surface ages on Mars must include smaller impact craters, typically a hundred meters in diameter, found on the area of interest.</p><p>To access to the crater population of this size range at a planetary scale we built a Crater Detection Algorithm (CDA) trained on THEMIS images where impact craters larger than 1 km from the Robbins & Hynek database have been identified. Our model offer a true detection rate of 0.9. We then applied our CDA on the global CTX mosaic within the ±45º latitudinal band leading to ~17 million of detection >100m in diameter.</p><p>The ultimate goal of our work is now to automatically compile smaller impact craters (5m<D<100m) visible on HiRISE imagery dataset offering a resolution of 25cm/px. We trained our algorithm on a part of the HiRISE mosaic (NASA/JPL/MSSS/The Murray Lab) covering a part of the Jezero crater (E77-5_N18_0) where 1650 craters have been manually identified. A portion of this population of craters has then be selected in order to be sure to include the most confident impact features in the training dataset, finally resulting to 1624 craters over this entire image.</p><p>Our model has been applied over the entire HiRISE mosaic covering the Jezero crater where more than 27,298 craters >3m have been detected. In order to validate our results, we compared the detection obtained on 30 tiles of 960px x 960px randomly chosen on a part of the mosaic (E77-25_N18-25) which have not been included into the training dataset with a manual identification, thus constituting the ground truth. For this purpose, we decided to categorize each tile according to the type of terrain mostly represented on each of them: rocky terrain, smooth terrain and dunes fields. We have also specified when the image exhibited some vertical stripes leading to the fourth category.</p><p>On rocky and smooth terrains, the CDA produce very good results: only 5% of detection on the average are false detection and 16% of craters on average have not been detected by the CDA. However, the CDA is less efficient on dune fields since 35% of detection are false detection and 15% of craters have not been identified. Finally, images exhibiting some vertical stripes significantly decrease the detection rate of the CDA since 56% of detection are false negative and 20% of craters have not been detected.</p>

The impact of a tear in the subducted Indian plate on the Miocene geology of the Himalayan-Tibetan orogen

2021 ◽  
Author(s):  
Rui Wang ◽  
Roberto F. Weinberg ◽  
Di-Cheng Zhu ◽  
Zeng-Qian Hou ◽  
Zhi-Ming Yang
Keyword(s):  
Geophysical Methods ◽  
Thermal Anomaly ◽  
Wide Band ◽  
Indian Plate ◽  
Thermal Anomalies ◽  
Mafic Enclaves ◽  
Indian Lithosphere ◽  
History Of ◽  
Isothermal Decompression ◽  
The Impact

The Yadong-Gulu Rift, cutting across the Gangdese belt and Himalayan terranes, is currently associated with a thermal anomaly in the mantle and crustal melting at 15−20 km depth. The rift follows the trace of a tear in the underthrusted Indian continental lithospheric slab recognized by high resolution geophysical methods. The Miocene evolution of a 400-km-wide band following the trace of the tear and the rift, records differences interpreted as indicative of a higher heat flow than its surroundings. In the Gangdese belt, this band is characterized by high-Sr/Y granitic magmatism that lasted 5 m.y. longer than elsewhere and by the highest values of εHf(i) and association with the largest porphyry Cu-Mo deposits in the Gangdese belt. Anomalously young magmatic rocks continue south along the rift in the Tethyan and Higher Himalayas. Here, a 300-km-wide belt includes some of the youngest Miocene Himalayan leucogranites; the only occurrence of mantle-derived mafic enclaves in a leucogranite; young mantle-derived lamprophyre dikes; and the youngest and hottest migmatites in the Higher Himalayas. These migmatites record a history of rapid exhumation contemporaneous with the exhumation of Miocene mafic eclogite blocks, which are unique to this region and which were both heated to >800 °C at ca. 15−13 Ma, followed by isothermal decompression. We suggest that the prominent tear in the Indian lithosphere, sub-parallel to the rift, is the most likely source for these tectono-thermal anomalies since the Miocene.

scholarly journals MAPPING OF PLANETARY SURFACE AGE BASED ON CRATER STATISTICS OBTAINED BY AN AUTOMATIC DETECTION ALGORITHM

2016 ◽  
Vol XLI-B4 ◽  
pp. 479-486
Author(s):  
A. L. Salih ◽  
M. Mühlbauer ◽  
A. Grumpe ◽  
J. H. Pasckert ◽  
C. Wöhler ◽  
...  
Keyword(s):  
Detection Threshold ◽  
Estimation Method ◽  
Image Data ◽  
Detection Algorithm ◽  
Image Resolution ◽  
Crater Floor ◽  
Planetary Surfaces ◽  
Size Frequency Distribution ◽  
Crater Detection ◽  
The Impact

The analysis of the impact crater size-frequency distribution (CSFD) is a well-established approach to the determination of the age of planetary surfaces. Classically, estimation of the CSFD is achieved by manual crater counting and size determination in spacecraft images, which, however, becomes very time-consuming for large surface areas and/or high image resolution. With increasing availability of high-resolution (nearly) global image mosaics of planetary surfaces, a variety of automated methods for the detection of craters based on image data and/or topographic data have been developed. In this contribution a template-based crater detection algorithm is used which analyses image data acquired under known illumination conditions. Its results are used to establish the CSFD for the examined area, which is then used to estimate the absolute model age of the surface. The detection threshold of the automatic crater detection algorithm is calibrated based on a region with available manually determined CSFD such that the age inferred from the manual crater counts corresponds to the age inferred from the automatic crater detection results. With this detection threshold, the automatic crater detection algorithm can be applied to a much larger surface region around the calibration area. The proposed age estimation method is demonstrated for a Kaguya Terrain Camera image mosaic of 7.4 m per pixel resolution of the floor region of the lunar crater Tsiolkovsky, which consists of dark and flat mare basalt and has an area of nearly 10,000 km<sup>2</sup>. The region used for calibration, for which manual crater counts are available, has an area of 100 km<sup>2</sup>. In order to obtain a spatially resolved age map, CSFDs and surface ages are computed for overlapping quadratic regions of about 4.4 x 4.4 km<sup>2</sup> size offset by a step width of 74 m. Our constructed surface age map of the floor of Tsiolkovsky shows age values of typically 3.2-3.3 Ga, while for small regions lower (down to 2.9 Ga) and higher (up to 3.6 Ga) age values can be observed. It is known that CSFD-derived absolute model ages can exhibit variations although the surface has a constant age. However, for four 10-20 km sized regions in the eastern part of the crater floor our map shows age values differing by several hundred Ma from the typical age of the crater floor, where the same regions are also discernible in Clementine UV/VIS color ratio image data probably due to compositional variations, such that the age differences of these four regions may be real.

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