Deep-water channel morphologies, architectures, and population densities in relation to stacking trajectories and climate states

2020 ◽  
Vol 133 (1-2) ◽  
pp. 287-306
Author(s):  
Chenglin Gong ◽  
Ronald J. Steel ◽  
Kun Qi ◽  
Yingmin Wang
Keyword(s):  
Deep Water ◽  
Water Channel ◽  
Lateral Migration ◽  
Population Densities ◽  
Submarine Channels ◽  
The Past ◽  
The Earth ◽  
Global Correlation ◽  
Lateral Channel ◽  
Low Degrees

Abstract Deep-water channel morphologies, stratigraphy, and population densities in relation to stacking trajectories and climate states remain poorly constrained, and are highlighted by a sampling of 142 submarine channels. From the perspective of channel kinematics, turbidite channels exhibit tripartite lateral - random - vertical trajectories or unidirectional channel-complex trajectories, whereas contourite channels display oblique upslope trajectories. Turbidite channels tend to be deep and narrow and have two to three times more lateral migration than contourite channels, whereas contourite channels tend to be shallow and wide and have two to three times more vertical accretion. We relate such differences between channel morphology and stratigraphy to density contrast between flow and ambient fluid for contourite versus turbidite channels, which seems to have favored lateral channel migration in turbidite channels but channel thalweg deposition in contourite channels. Additionally, channels formed during a greenhouse climate state display low degrees of morphological and architectural variations, and are the minority in our global channel database (8% of total), although the Earth has been in a greenhouse state for 72% of the past 540 m.y. Icehouse channels, in contrast, exhibit high amplitudes of morphological and architectural variations and are the majority in the global channel family (92% of total), although the Earth has been in an icehouse state for 18% of the past 540 m.y. Such differences in channel-population densities between greenhouse and icehouse climates (8% versus 92%) suggest a weak global correlation of channel-population densities with warming greenhouse climates.

scholarly journals Supplemental Material: Deep-water channel morphologies, architectures, and population densities in relation to stacking trajectories and climate states

2020 ◽  
Author(s):  
Chenglin Gong
Keyword(s):  
Deep Water ◽  
Water Channel ◽  
Water Channels ◽  
Population Densities

Morphometrics and architectures of 142 chosen deep-water channels and their relation to stacking trajectories and climates.

scholarly journals Supplemental Material: Deep-water channel morphologies, architectures, and population densities in relation to stacking trajectories and climate states

2020 ◽  
Author(s):  
Chenglin Gong
Keyword(s):  
Deep Water ◽  
Water Channel ◽  
Water Channels ◽  
Population Densities

Morphometrics and architectures of 142 chosen deep-water channels and their relation to stacking trajectories and climates.

The Origin of the Moon and its Relationship to the Origin of the Solar System

1962 ◽  
Vol 14 ◽  
pp. 133-148 ◽  
Author(s):  
Harold C. Urey
Keyword(s):  
Solar System ◽  
The Moon ◽  
The Past ◽  
The Earth ◽  
Short Period ◽  
Origin Of The Moon

During the last 10 years, the writer has presented evidence indicating that the Moon was captured by the Earth and that the large collisions with its surface occurred within a surprisingly short period of time. These observations have been a continuous preoccupation during the past years and some explanation that seemed physically possible and reasonably probable has been sought.

scholarly journals Calibration of Radiocarbon Dates for the Late Pleistocene Using U/Th Dates on Stalagmites

Radiocarbon ◽  
1997 ◽  
Vol 39 (1) ◽  
pp. 27-32 ◽  
Author(s):  
John C. Vogel ◽  
Joel Kronfeld
Keyword(s):  
South Africa ◽  
Magnetic Dipole ◽  
Satisfactory Agreement ◽  
Late Pleistocene ◽  
Calibration Curve ◽  
Dipole Field ◽  
Radiocarbon Dates ◽  
The Past ◽  
The Earth ◽  
Magnetic Dipole Field

Twenty paired 14C and U/Th dates covering most of the past 50,000 yr have been obtained on a stalagmite from the Cango Caves in South Africa as well as some additional age-pairs on two stalagmites from Tasmania that partially fill a gap between 7 ka and 17 ka ago. After allowance is made for the initial apparent 14C ages, the age-pairs between 7 ka and 20 ka show satisfactory agreement with the coral data of Bard et al. (1990, 1993). The results for the Cango stalagmite between 25 ka and 50 ka show the 14C dates to be substantially younger than the U/Th dates except at 49 ka and 29 ka, where near correspondence occurs. The discrepancies may be explained by variations in 14C production caused by changes in the magnetic dipole field of the Earth. A tentative calibration curve for this period is offered.

Plant leaf recognition with shallow and deep learning: A comprehensive study

2020 ◽  
Vol 24 (6) ◽  
pp. 1311-1328
Author(s):  
Jozsef Suto
Keyword(s):  
Machine Learning ◽  
Plant Species ◽  
Research Area ◽  
Research Papers ◽  
Plant Leaf ◽  
Leaf Characteristics ◽  
The Past ◽  
The Earth ◽  
Test Sets ◽  
Comprehensive Study

Nowadays there are hundreds of thousands known plant species on the Earth and many are still unknown yet. The process of plant classification can be performed using different ways but the most popular approach is based on plant leaf characteristics. Most types of plants have unique leaf characteristics such as shape, color, and texture. Since machine learning and vision considerably developed in the past decade, automatic plant species (or leaf) recognition has become possible. Recently, the automated leaf classification is a standalone research area inside machine learning and several shallow and deep methods were proposed to recognize leaf types. From 2007 to present days several research papers have been published in this topic. In older studies the classifier was a shallow method while in current works many researchers applied deep networks for classification. During the overview of plant leaf classification literature, we found an interesting deficiency (lack of hyper-parameter search) and a key difference between studies (different test sets). This work gives an overall review about the efficiency of shallow and deep methods under different test conditions. It can be a basis to further research.

scholarly journals Trajectories of the Earth System in the Anthropocene

2018 ◽  
Vol 115 (33) ◽  
pp. 8252-8259 ◽  
Author(s):  
Will Steffen ◽  
Johan Rockström ◽  
Katherine Richardson ◽  
Timothy M. Lenton ◽  
Carl Folke ◽  
...  
Keyword(s):  
Global Economy ◽  
Human Action ◽  
Behavioral Changes ◽  
Earth System ◽  
New Governance ◽  
Sea Levels ◽  
Average Temperature ◽  
The Past ◽  
The Earth ◽  
Potential Threshold

We explore the risk that self-reinforcing feedbacks could push the Earth System toward a planetary threshold that, if crossed, could prevent stabilization of the climate at intermediate temperature rises and cause continued warming on a “Hothouse Earth” pathway even as human emissions are reduced. Crossing the threshold would lead to a much higher global average temperature than any interglacial in the past 1.2 million years and to sea levels significantly higher than at any time in the Holocene. We examine the evidence that such a threshold might exist and where it might be. If the threshold is crossed, the resulting trajectory would likely cause serious disruptions to ecosystems, society, and economies. Collective human action is required to steer the Earth System away from a potential threshold and stabilize it in a habitable interglacial-like state. Such action entails stewardship of the entire Earth System—biosphere, climate, and societies—and could include decarbonization of the global economy, enhancement of biosphere carbon sinks, behavioral changes, technological innovations, new governance arrangements, and transformed social values.

An ecological shift in a remote coral atoll of Belize over 25 years

1998 ◽  
Vol 25 (2) ◽  
pp. 122-130 ◽  
Author(s):  
TIMOTHY R. McCLANAHAN ◽  
NYAWIRA A. MUTHIGA
Keyword(s):  
Central America ◽  
Major Change ◽  
Acropora Cervicornis ◽  
Hard Coral ◽  
Population Densities ◽  
Herbivorous Fishes ◽  
Patch Reefs ◽  
The Past ◽  
Algal Abundance ◽  
The Caribbean

Many coral reefs in the Caribbean, and elsewhere, have undergone changes from hard coral to fleshy algal dominance over the past two decades which has often been interpreted as a localized response to eutrophication and fishing. Here, data on the abundance of hard corals and algae from lagoonal patch reefs distributed throughout a large (260 km2) remote reef atoll located approximately 30 km offshore from the sparsely-populated coast of Belize, Central America, are compared with a study of these patch reefs conducted 25 years previously. Data and observations indicate that these patch reefs have undergone a major change in their ecology associated with a 75% reduction in total hard coral, a 99% loss in the cover of Acropora cervicornis and A. palmata, and a 315% increase in algae, which are mostly erect brown algae species in the genera Lobophora, Dictyota, Turbinaria and Sargassum. Such changes have been reported from other Caribbean reefs during the 1980s, but not on such a remote reef and the present changes may be attributed primarily to both a disease that began killing Acropora in this region in the mid 1980s and a reduction in herbivory. The low level of herbivory may be attributable to the disease-induced loss of the sea urchin Diadema antillarum in 1983, or fishing of herbivorous fishes, but both explanations are speculative. The present density of fisherfolk is low, and their efforts are not targetted at herbivorous fishes, and population densities of D. antillarum 14 years after the mortality are <1 individual per 1000 m2, but there is no comparative data from before the die off. There is, however, no indication that these major changes occurred on the fore reef, because A. palmata is abundant and erect algal abundance is low. We suggest that reported changes in other Caribbean reefs are not necessarily or exclusively influenced by local human factors such as localized intense eutrophication or fishing.

Whither democracy? Religion, politics and Islam

2011 ◽  
Vol 37 (4) ◽  
pp. 437-448 ◽  
Author(s):  
Fred Dallmayr
Keyword(s):  
Political Institutions ◽  
Religious Faith ◽  
Christian Right ◽  
Political Islam ◽  
The Past ◽  
The Earth ◽  
The World ◽  
Democratic Character

The question raised by the article is: can democracy be religious and, if so, how? Can religious faith be reconciled with modern democratic political institutions? The article takes its departure from the biblical admonition to believers to be ‘the salt of the earth’ — a phrase that militates against both world dominion and world denial. In its long history, Islam (like Christianity) has been sorely tempted by the lure of worldly power and domination. Nor is this temptation entirely a matter of the past (witness the rise of the Christian right and of ‘political Islam’ in our time). Focusing on contemporary Iran, the article makes a constitutional proposal which would strengthen the democratic character of the Iranian Republic without canceling religious faith. If adopted, the proposal would reinvigorate the ‘salt’ of Muslim faith thus enabling believers to live up to the Qur‘anic summons for freedom, justice and service in the world.

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