The role of impacts on Archaean tectonics

Abstract Field evidence from the Pilbara craton (Australia) and Kaapvaal craton (South Africa) indicate that modern tectonic processes may have been operating at ca. 3.2 Ga, a time also associated with a high density of preserved Archaean impact indicators. Recent work has suggested a causative association between large impacts and tectonic processes for the Hadean. However, impact flux estimates and spherule bed characteristics suggest impactor diameters of <100 km at ca. 3.5 Ga, and it is unclear whether such impacts could perturb the global tectonic system. In this work, we develop numerical simulations of global tectonism with impacting effects, and simulate the evolution of these models throughout the Archaean for given impact fluxes. We demonstrate that moderate-size (∼70 km diameter) impactors are capable of initiating short-lived subduction, and that the system response is sensitive to impactor size, proximity to other impacts, and also lithospheric thickness gradients. Large lithospheric thickness gradients may have first appeared at ca. 3.5–3.2 Ga as cratonic roots, and we postulate an association between Earth’s thermal maturation, cratonic root stability, and the onset of widespread sporadic tectonism driven by the impact flux at this time.

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The Possible Role Of Toll-Like Receptor 4 In The Pathology Of Stroke

Advances in Bioscience and Clinical Medicine ◽

10.7575/aiac.abcmed.ca1.8 ◽

2017 ◽

pp. 8

Author(s):

Mohammad Allahtavakoli ◽

Ali Shamsizadeh ◽

Ali Roohbakhsh ◽

Amir Moghadam-Ahmadi ◽

Mohammad Reza Rahmani ◽

...

Keyword(s):

Innate Immunity ◽

Inflammatory Response ◽

System Response ◽

Toll Like Receptor ◽

Key Factors ◽

Toll Like Receptor 4 ◽

Brain Functions ◽

Essential Components ◽

The Impact

Stroke is a prevalent and dangerous health problem, which triggers an intense inflammatory response to Toll-like receptors (TLRs) activation. TLRs are the essential components of innate immunity system response, and therefore, they are one of the key factors involved in recognizing pathogens and internal ligands. Among TLRs, TLR4 significantly participates in the induction of inflammation and brain functions, hence, it has been hypothesized that this molecule is associated with several brain immune-related diseases such as stroke. It has also been proved that animals with TLR4 deficiency have higher protection against ischemia and the absence of TLR4 reduces the neuroinflammation and injuries associated with brain trauma. TLR4 deficiency may play a neuroprotective role in the occurrence of stroke. This article will review recent information regarding the impact of TLR4 in the pathogenicity of stroke.

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Paleo-Drainage Network, Morphotectonics, and Fluvial Terraces: Clues from the Verde Stream in the Middle Sangro River (Central Italy)

Geosciences ◽

10.3390/geosciences8090337 ◽

2018 ◽

Vol 8 (9) ◽

pp. 337 ◽

Cited By ~ 8

Author(s):

Enrico Miccadei ◽

Cristiano Carabella ◽

Giorgio Paglia ◽

Tommaso Piacentini

Keyword(s):

Drainage Basin ◽

Central Italy ◽

General Setting ◽

River Valley ◽

Drainage Network ◽

Fluvial Terraces ◽

Field Evidence ◽

Basin Scale ◽

The Impact

This work analyzes the role of paleo-drainage network, morphotectonics, and surface processes in landscape evolution in a sector of the transition zone between the chain and the piedmont area of Central Apennines. Particularly, it focuses on the Verde Stream, a tributary of the middle Sangro River valley, which flows in the southeastern Abruzzo area at the boundary with the Molise region. The Verde Stream was investigated through a drainage basin scale geomorphological analysis incorporating the morphometry of the orography and hydrography, structural geomorphological field mapping, and the investigation of morphological field evidence of tectonics with their statistical azimuthal distributions. The local data obtained were compared with the analysis of the middle Sangro River valley and the tectonic features of the Abruzzo–Molise area. This approach led us to also provide relevant clues about the definition of the role of karst features and paleo-landscapes in the general setting of the study area and to identify the impact of active tectonics, confirmed by recent and active seismicity. In conclusion, the paper contributes to defining the main stages of the geomorphological evolution of this area, driven by uplift and local tectonics and due to a combination of fluvial, karst, and landslide processes.

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Intergroup Threat and Outgroup Attitudes

Social Psychology ◽

10.1027/1864-9335/a000127 ◽

2013 ◽

Vol 44 (5) ◽

pp. 311-319 ◽

Cited By ~ 12

Author(s):

Marco Brambilla ◽

David A. Butz

Keyword(s):

Gay Men ◽

Social Group ◽

Welfare Recipients ◽

Intergroup Attitudes ◽

Social Policies ◽

Intergroup Threat ◽

Economic Threat ◽

The Impact ◽

General Climate

Two studies examined the impact of macrolevel symbolic threat on intergroup attitudes. In Study 1 (N = 71), participants exposed to a macrosymbolic threat (vs. nonsymbolic threat and neutral topic) reported less support toward social policies concerning gay men, an outgroup whose stereotypes implies a threat to values, but not toward welfare recipients, a social group whose stereotypes do not imply a threat to values. Study 2 (N = 78) showed that, whereas macrolevel symbolic threat led to less favorable attitudes toward gay men, macroeconomic threat led to less favorable attitudes toward Asians, an outgroup whose stereotypes imply an economic threat. These findings are discussed in terms of their implications for understanding the role of a general climate of threat in shaping intergroup attitudes.

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