نتایج جستجو برای: trace fossil

تعداد نتایج: 91986  

2005
Tzu-chien Chiu Richard G. Fairbanks Richard A. Mortlock Arthur L. Bloom

Fossil coral is an excellent archive to extend the radiocarbon (C) calibration beyond tree-ring records; however, published coral data older than 26,000 years before present are too disparate for practical calibration. We propose an explanation for these discrepancies: trace amounts of secondary calcite and organic matter in fossil corals shift the C ages toward younger ages. In a series of aci...

2016
Jennifer F. Parker Philip J. Hopley Brian F. Kuhn

The Buxton-Norlim Limeworks southwest of Taung, South Africa, is renowned for the discovery of the first Australopithecus africanus fossil, the 'Taung Child'. The hominin was recovered from a distinctive pink calcrete that contains an abundance of invertebrate ichnofauna belonging to the Coprinisphaera ichnofacies. Here we describe the first fossil bee's nest, attributed to the ichnogenus Celli...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه لرستان 1390

این رساله را با مفاهیم و قضایای اساسی آغاز می کنیم. سپس عملگر اسکتن و trace class را تعریف می کنیم و نشان می دهیم یک جبرژردان از عملگرهای شبه پوچ توان و فشرده شامل عملگر trace class ، زیرفضای پایا دارد. هم چنین نشان می دهیم یک جبر ژردان از عملگرهای شبه پوچ توان اسکتن مثلثی شونده است. در نهایت به بررسی ویژگی های عملگرهای کراندار که در شرایط طیفی جمعی و ضربی صدق می کنند می پردازیم و نتایج آنها را...

2003
J. Scott Turner

Organism-built structures have long been useful artifacts for students of evolution and systematics, because they represent a permanent record of a set of behaviors. These structures also represent an investment of energy by an organism, and to persist in the fossil record, the energetic investment in the structure must pay off for the organisms that build it, in either improved survivorship, i...

Journal: :iranian journal of astronomy and astrophysics 2014
habib g. khosroshahi louisa a. nolan

it is inferred from the symmetrical and luminous x-ray emission of fossil groups that they are mature, relaxed galaxy systems. cosmological simulations and observations focusing on their dark halo and inter-galactic medium properties confirm their early formation. recent photometric observations suggest that, unlike the majority of non-fossil brightest group galaxies (bggs), the central early-t...

Journal: :Environmental humanities 2022

In this paper, we study the environmental consequences of fossil fuel extraction. In our model, there is a cartel of fossil fuel suppliers and a coalition of fossil fuel buyers. The cartel maximizes her profits without taking into account the negative environmental externalities of her productions. However, since consumers are suffered by environmental emissions of fossil fuels, the coalition i...

Journal: :iranian journal of public health 0
k. imandel m. ghotbi-ravandi n. moazami m. mazaheri asadi

fossil fuel power plant is one of the most important sources of environmental pollution of the vanadium toxic metal. this survey showed that the penicilium austuranium is the best microorganism for biosorption of vanadium isolated from environment of fossil fuel power plant. to determine the optimum ph and most biosorption and accumulation of vanadium by these fungi, power plants wastewater, pa...

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