Time And Space
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2021 ◽  
Author(s):  
Yapeng Zhao ◽  
Liang Kong ◽  
Lele Liu ◽  
Jiaqi Liu

Abstract The decomposition of natural gas hydrate will reduce the cementation effect of hydrate and produce ultra-static pore pressure, which will change the mechanical characteristics of the reservoir. Eventually, a series of geological disasters could be triggered, of which the submarine landslide is a typical example. In order to analyze the stability of hydrate-bearing submarine slopes and to explore the internal relationship between hydrate decomposition and submarine landslides, a “two-step reduction method” was described in this paper. This method was based on a strength reduction approach, which can be used to assess the effects of the initial geostress balance and hydrate decomposition on substrate strength reduction. This method was used to reveal the essence of hydrate decomposition and then a joint operation mode of multi-well was proposed. The internal relationship between hydrate decomposition and submarine landslides were analyzed in detail. And the development process and mechanism of submarine landslide were deeply discussed. The results showed that hydrate decomposition is a dynamic process of stress release and displacement, where the “stress inhomogeneity” distributed along the slope is transformed into “displacement inhomogeneity”. We concluded that hydrate decomposition could trigger a submarine landslide, especially along a sliding surface. The formation of submarine landslide is a gradual development process, and presents the dual characteristics of time and space.


2021 ◽  
Vol 9 (12) ◽  
pp. 2472
Author(s):  
Fernando Puente-Sánchez ◽  
Max Chavarría

Extreme environments are fascinating ecosystems that have allowed us to increase our knowledge about the evolutionary processes of life [...]


2021 ◽  
Vol 5 (11) ◽  
pp. 188-191
Author(s):  
Qiaohong Cheng

After-school service is an effective arrangement of time and space for students after school hours. Its demand and value are under the strong advocacy and implementation of national policies to establish a “people-oriented” concept while focusing on students’ development and pursuing educational equity.


2021 ◽  
Author(s):  
Jayanta Pal ◽  
Soumen Ghosh ◽  
Bansibadan Maji ◽  
Dilip Kumar Bhattacharya

Abstract Similarity/dissimilarity study of protein and genome sequences remains a challenging task and selection of techniques and descriptors to be adopted, plays an important role in computational biology. Again, genome sequence comparison is always preferred to protein sequence comparison due the presence of 20 amino acids in protein sequence compared to only 4 nucleotides in genome sequence. So it is important to consider suitable representation that is both time and space efficient and also equally applicable to protein sequences of equal and unequal lengths. In the binary form of representation, Fourier transform of a protein sequence reduces to the transformation of 20 simple binary sequences in Fourier domain, where in each such sequence, Perseval’s Identity gives a very simple computable form of power spectrum. This gives rise to readily acceptable forms of moments of different degrees. Again such moments, when properly normalized, show a monotonically descending trend with the increase in the degrees of the moments. So it is better to stick to moments of smaller degrees only. In this paper, descriptors are taken as 20 component vectors, where each component corresponds to a general second order moment of one of the 20 simple binary sequences. Then distance matrices are obtained by using Euclidean distance as the distance measure between each pair of sequence. Phylogenetic trees are obtained from the distance matrices using UPGMA algorithm. In the present paper, the datasets used for similarity/dissimilarity study are 9 ND4, 16 ND5, 9 ND6, 24 TF proteins and 12 Baculovirus proteins. It is found that the phylogenetic trees produced by the present method are at par with those produced by the earlier methods adopted by other authors and also their known biological references. Further it takes less computational time and also it is equally applicable to sequences of equal and unequal lengths.


2021 ◽  
pp. 089692052110492
Author(s):  
Tom Brass

The political importance of Chayanov transcends his own time and space, influencing as it has done – and continues to do – both the debate about rural development in Third World countries and – more broadly – resurgent agrarian populist interpretations in academia and elsewhere. Less well known, but epistemologically as revealing of his politics, are his non-economic writings, particularly his contributions to the Gothic literary genre. Examined here, therefore, are three stories written pseudonymously by Chayanov, each of which is structured by the same discourse. All were composed over a short period just after the Bolsheviks took power in Russia, and reveal as a sub-text the political divergence and concomitant struggle between neo-populist and Bolshevik versions of societal development.


Author(s):  
Bhairabi Prasad Sahu

This article focuses on the shifts in the ways of seeing the history and historiography of the emergence of agrarian landscapes, manufacture of crafts, and trade and commerce in north India, during the mid-first millennium bce to the 13th century. Continued manifestation of settled agrarian localities, or janapadas, with its attendant concomitant processes, is visibly more noticeable from the middle of the first millennium ce onward, though their early beginnings can be traced back to the later Vedic times. The study of the janapadas or localities and regions, as distinguished from earlier regional studies, focusing on the trajectory of sociopolitical developments through time is a development dating to around the turn of the 21st century. It has much to do with the recognition of the fact that historical or cultural regions and modern state boundaries, which are the result of administrative decision-making, do not necessarily converge. Simultaneously, instead of engaging in macro-generalizations, historians have moved on to acknowledge that spaces in the past, as in the present, were differentiated, and there were uneven patterns of growth across regions and junctures. Consequently, since 1990 denser and richer narratives of the regions have been available. These constructions in terms of the patterns for early India have moved away from the earlier accounts of wider generalizations in time and space, colonization by Gangetic north India, and crisis. Alternatively, they look for change through continuities and try to problematize issues that were earlier subsumed under broader generalizations, and provide local and regional societies with the necessary agency. Rural settlements and rural society through the regions are receiving their due, and so are their networks of linkages with artisanal production, markets, merchants, and trade. The grades of peasants, markets, and merchants as well as their changing forms have attracted the notice of the historian. This in turn has compelled a shift in focus from being mostly absorbed with subcontinental history to situating it in its Asiatic and Indian Ocean background.


Author(s):  
Irina Panyushkina ◽  
David M Meko ◽  
Alexander Shiklomanov ◽  
Richard D Thaxton ◽  
Vladimyr Myglan ◽  
...  

Abstract The Yenisei River is the largest contributor of freshwater and energy fluxes among all rivers draining to the Arctic Ocean. Modeling long-term variability of Eurasian runoff to the Arctic Ocean is complicated by the considerable variability of river discharge in time and space, and the monitoring constraints imposed by a sparse gauged-flow network and paucity of satellite data. We quantify tree growth response to river discharge at the upper reaches of the Yenisei River in Tuva, South Siberia. Two regression models built from eight tree-ring width chronologies of Larix sibirica are applied to reconstruct winter (Nov–Apr) discharge for the period 1784-1997 (214 years), and annual (Oct–Sept) discharge for the period 1701–2000 (300 years). The Nov–Apr model explains 52% of the discharge variance whereas Oct–Sept explains 26% for the calibration intervals 1927–1997 and 1927-2000, respectively. This new hydrological archive doubles the length of the instrumental discharge record at the Kyzyl gauge and resets the temporal background of discharge variability back to 1784. The reconstruction finds a remarkable 80% upsurge in winter flow over the last 25 years, which is unprecedented in the last 214 years. In contrast, annual discharge fluctuated normally for this system, with only a 7% increase over the last 25 years. Water balance modeling with CRU data manifests a significant discrepancy between decadal variability of the gauged flow and climate data after 1960. We discuss the impact on the baseflow rate change of both the accelerating permafrost warming in the discontinuous zone of South Siberia and widespread forest fires. The winter discharge accounts for only one-third of the annual flow, yet the persistent 25-year upsurge is alarming. This trend is likely caused by Arctic Amplification, which can be further magnified by increased winter flow delivering significantly more freshwater to the Kara Sea during the cold season.


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