نتایج جستجو برای: mass extinction

تعداد نتایج: 500636  

Journal: :Geology 2022

Abstract High-resolution biomarker and compound-specific isotope distributions coupled with the degradation of calcareous fossil remnants reveal that intensive euxinia decalcification (acidification) driven by Central Atlantic magmatic province (CAMP) activity formed a two-pronged kill mechanism at end-Triassic mass extinction. In newly proposed extinction interval for basal Blue Lias Formation...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2002
David Jablonski

Because many survivors of mass extinctions do not participate in postrecovery diversifications, and therefore fall into a pattern that can be termed "Dead Clade Walking" (DCW), the effects of mass extinctions extend beyond the losses observed during the event itself. Analyses at two taxonomic levels provide a first-order test of the prevalence of DCWs by using simple and very conservative opera...

2014
JUNGMI KWON MOTOHIDE TAMURA JAMES H. HOUGH NOBUHIKO KUSAKABE TETSUYA NAGATA YASUSHI NAKAJIMA PHIL W. LUCAS TAKAHIRO NAGAYAMA RYO KANDORI

We have conducted a systematic near-infrared circular polarization (CP) survey in star-forming regions, covering high-mass, intermediate-mass, and low-mass young stellar objects. All the observations were made using the SIRPOL imaging polarimeter on the Infrared Survey Facility 1.4 m telescope at the South African Astronomical Observatory. We present the polarization properties of ten sub-regio...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2012
Ence Yang Lingling Xu Ying Yang Xinyu Zhang Meichun Xiang Chengshu Wang Zhiqiang An Xingzhong Liu

Carnivorism is one of the basic life strategies of fungi. Carnivorous fungi possess the ability to trap and digest their preys by sophisticated trapping devices. However, the origin and development of fungal carnivorism remains a gap in evolution biology. In this study, five protein-encoding genes were used to construct the phylogeny of the carnivorous fungi in the phylum Ascomycota; these fung...

AbbasAli Vafaei, Adel Kashefi, Ali Rashidy-Pour, Fatemeh Taherian, Gholam Hassan Vaezi, Sharaf Eskandarian,

Introduction: One of the hallmark symptoms of posttraumatic stress disorder (PTSD) is the impaired extinction of traumatic memory. Single prolonged stress (SPS) has been suggested as an animal model of PTSD, since SPS rats exhibited the impaired fear extinction. Oxytocin (OXT) has been recently suggested as a potential pharmacotherapy for treatment of PTSD. In this study, using SPS rats we inve...

Journal: :Science 2005
Raymond B Huey Peter D Ward

A catastrophic extinction occurred at the end of the Permian Period. However, baseline extinction rates appear to have been elevated even before the final catastrophe, suggesting sustained environmental degradation. For terrestrial vertebrates during the Late Permian, the combination of a drop in atmospheric oxygen plus climate warming would have induced hypoxic stress and consequently compress...

Journal: :Science 2004
Gregory P Dietl Gregory S Herbert Geerat J Vermeij

Extinction may alter competitive interactions among surviving species, affecting their subsequent recovery and evolution, but these processes remain poorly understood. Analysis of predation traces produced by shell-drilling muricid snails on bivalve prey reveals that species interactions were substantially different before and after a Plio-Pleistocene mass extinction in the western Atlantic. Mu...

2003
P. G. Pérez-González A. Gil de Paz J. Zamorano J. Gallego

We present an analysis of the integrated properties of the stellar populations in the Universidad Complutense de Madrid (UCM) Survey of Hα-selected galaxies. In this paper, the first of a series, we describe in detail the techniques developed to model star-forming galaxies using a mixture of stellar populations, and taking into account the observational uncertainties. We assume a recent burst o...

Journal: :The Journal of neuroscience : the official journal of the Society for Neuroscience 2010
Nigel Whittle Markus Hauschild Gert Lubec Andrew Holmes Nicolas Singewald

Fear extinction is impaired in neuropsychiatric disorders, including posttraumatic stress disorder. Identifying drugs that facilitate fear extinction in animal models provides leads for novel pharmacological treatments for these disorders. Zinc (Zn) is expressed in neurons in a cortico-amygdala circuit mediating fear extinction, and modulates neurotransmitter systems regulating extinction. We p...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2017
John Alroy

It is widely expected that habitat destruction in the tropics will cause a mass extinction in coming years, but the potential magnitude of the loss is unclear. Existing literature has focused on estimating global extinction rates indirectly or on quantifying effects only at local and regional scales. This paper directly predicts global losses in 11 groups of organisms that would ensue from dist...

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