Deconstructing Olduvai Domínguez-Rodrigo, Manuel; Barba, Rebeca; Egeland, Charles P
2007, 2007-07-05
eBook
The Olduvai Bed I archaeological sites, dating back to almost 2 million years, have been at the epicenter of the debate on how early humans behaved. This book presents a new analytical approach ...which, after having been applied to these sites, has produced unexpected results: the association of stone tools and faunal remains at most Olduvai Bed I sites is accidental and not related to hominid behavior. Only at one site, FLK Zinj, is this association intentional. Through careful taphonomic analysis of this site, coupled with detailed experimental work, it is possible to rule out the hypothesis that hominids were passive scavengers. Hominids were targeting meat in the exploitation of animals, which they probably obtained through some degree of predation, and their behavior seems to have been more advanced than previously thought.
What bugged the dinosaurs? Poinar, George O; Poinar, Roberta
2008, 2010., 20100101, 2010, 2008-01-01
eBook, Book
Millions of years ago in the Cretaceous period, the mighty Tyrannosaurus rex--with its dagger-like teeth for tearing its prey to ribbons--was undoubtedly the fiercest carnivore to roam the Earth. Yet ...asWhat Bugged the Dinosaurs?reveals, T. rex was not the only killer. George and Roberta Poinar show how insects--from biting sand flies to disease-causing parasites--dominated life on the planet and played a significant role in the life and death of the dinosaurs.
The Poinars bring the age of the dinosaurs marvelously to life. Analyzing exotic insects fossilized in Cretaceous amber at three major deposits in Lebanon, Burma, and Canada, they reconstruct the complex ecology of a hostile prehistoric world inhabited by voracious swarms of insects. The Poinars draw upon tantalizing new evidence from their amazing discoveries of disease-producing vertebrate pathogens in Cretaceous blood-sucking flies, as well as intestinal worms and protozoa found in fossilized dinosaur excrement, to provide a unique view of how insects infected with malaria, leishmania, and other pathogens, together with intestinal parasites, could have devastated dinosaur populations.
A scientific adventure story from the authors whose research inspiredJurassic Park,What Bugged the Dinosaurs?? offers compelling evidence of how insects directly and indirectly contributed to the dinosaurs' demise.
The walking whales Thewissen, J. G. M; Dillard, Jacqueline
2014., 20141113, 2014, 2014-11-13
eBook
Hans Thewissen, a leading researcher in the field of whale paleontology and anatomy, gives a sweeping first-person account of the discoveries that brought to light the early fossil record of whales. ...As evidenced in the record, whales evolved from herbivorous forest-dwelling ancestors that resembled tiny deer to carnivorous monsters stalking lakes and rivers and to serpentlike denizens of the coast. Thewissen reports on his discoveries in the wilds of India and Pakistan, weaving a narrative that reveals the day-to-day adventures of fossil collection, enriching it with local flavors from South Asian culture and society. The reader senses the excitement of the digs as well as the rigors faced by scientific researchers, for whom each new insight gives rise to even more questions, and for whom at times the logistics of just staying alive may trump all science. In his search for an understanding of how modern whales live their lives, Thewissen also journeys to Japan and Alaska to study whales and wild dolphins. He finds answers to his questions about fossils by studying the anatomy of otters and porpoises and examining whale embryos under the microscope. In the book's final chapter, Thewissen argues for approaching whale evolution with the most powerful tools we have and for combining all the fields of science in pursuit of knowledge.
The microscopic examination of fossilized bone tissue is a sophisticated and increasingly important analytical tool for understanding the life history of ancient organisms. This book provides an ...essential primer and manual for using fossil bone histology to investigate the biology of extinct tetrapods. Twelve experts summarize advances in the field over the past three decades, reviewing fundamental basics of bone microanatomy and physiology. Research specimen selection, thin-section preparation, and data analysis are addressed in detail. The authors also outline methods and issues in bone growth rate calculation and chronological age determination, as well as how to examine broader questions of behavior, ecology, and evolution by studying the microstructure of bone.
Net anthropogenic emissions of carbon dioxide (CO
) must approach zero by mid-century (2050) in order to stabilize the global mean temperature at the level targeted by international efforts
. Yet ...continued expansion of fossil-fuel-burning energy infrastructure implies already 'committed' future CO
emissions
. Here we use detailed datasets of existing fossil-fuel energy infrastructure in 2018 to estimate regional and sectoral patterns of committed CO
emissions, the sensitivity of such emissions to assumed operating lifetimes and schedules, and the economic value of the associated infrastructure. We estimate that, if operated as historically, existing infrastructure will cumulatively emit about 658 gigatonnes of CO
(with a range of 226 to 1,479 gigatonnes CO
, depending on the lifetimes and utilization rates assumed). More than half of these emissions are predicted to come from the electricity sector; infrastructure in China, the USA and the 28 member states of the European Union represents approximately 41 per cent, 9 per cent and 7 per cent of the total, respectively. If built, proposed power plants (planned, permitted or under construction) would emit roughly an extra 188 (range 37-427) gigatonnes CO
. Committed emissions from existing and proposed energy infrastructure (about 846 gigatonnes CO
) thus represent more than the entire carbon budget that remains if mean warming is to be limited to 1.5 degrees Celsius (°C) with a probability of 66 to 50 per cent (420-580 gigatonnes CO
)
, and perhaps two-thirds of the remaining carbon budget if mean warming is to be limited to less than 2 °C (1,170-1,500 gigatonnes CO
)
. The remaining carbon budget estimates are varied and nuanced
, and depend on the climate target and the availability of large-scale negative emissions
. Nevertheless, our estimates suggest that little or no new CO
-emitting infrastructure can be commissioned, and that existing infrastructure may need to be retired early (or be retrofitted with carbon capture and storage technology) in order to meet the Paris Agreement climate goals
. Given the asset value per tonne of committed emissions, we suggest that the most cost-effective premature infrastructure retirements will be in the electricity and industry sectors, if non-emitting alternatives are available and affordable
.
Permeability upscaling in carbonate rocks is challenging due to the heterogeneity at multiple scales. Although there are several computational methods for permeability upscaling, the applicability, ...computational time, and the associated accuracy of these methods may vary significantly. This article modified an established Karim and Krabbenhoft renormalization method (KRM) and proposed a regression-based renormalization for permeability upscaling in carbonate rocks, and the results are compared with the classical KRM. To this end, permeability at the small-scale samples (size = 5003 and 6003 voxels, from 405 to 7944 μm3) and the whole core plug scale are computed from three carbonate samples of varying heterogeneity and composition using pore network models extracted from 3D micro-CT images. Subsequently, the modified regression-based renormalization method is applied to calculate the regression (upscaled) permeability. Our results indicate that the regression permeability is in good agreement with experimental permeability for full-size core plug estimations (maximum error = 11.07%) using the proposed RKRM approachsuggesting the accuracy of this method. Furthermore, the relative error of the permeability estimation from small-scale samples using KRM was much higher than those of the RKRMsuggesting the superiority of the proposed approach over the classical one. The observed errors in permeability using the RKRM approach, despite being lower than the classical KRM approach, are attributed to the heterogeneity of carbonate samples at the sub-core and core scales. The results of this study thus add to the general understanding of permeability upscaling in carbonates and the associated impact of heterogeneity.
The National Energy Technology Laboratory, the Japan Oil, Gas and Metals National Corporation, and the U.S. Geological Survey are leading an effort to conduct an extended gas hydrate production test ...in northern Alaska. The proposed production test required the drilling of an initial stratigraphic test well (STW) to confirm the geologic conditions of the proposed test site. This well was completed in January 2019 in cooperation with the Prudhoe Bay Unit Working Interest Owners. The Prudhoe Bay Unit Hydrate-01 STW was spudded on 10-December-2018. Downhole data acquisition was completed on 25-December-2018, and the rig was released on 01-January-2019. The Hydrate-01 STW was drilled in two sections, including the surface hole that was drilled to a depth of 2248 ft measured depth (MD) (685 m MD) and cased, and the production hole section that was drilled to a depth of 3558 ft MD (1084 m MD) and also cased. A thermally chilled mineral-oil-based mud was used in the main (production) hole section of the well to maintain wellbore stability and quality of the wellbore acquired data. The primary wellbore data were acquired using logging-while-drilling tools. A sidewall pressure core system was also deployed to gather grain size and other data needed for the design of the future production test wells. In addition to confirming the geologic conditions at the test site, the Hydrate-01 STW was designed to serve as a monitoring well during future field operations. Therefore, two sets of fiber-optic cables, each including a bundled distributed acoustic sensor (DAS) and a distributed temperature sensor (DTS), were clamped to the outside of the production casing and cemented in place. In March 2019, the project team acquired three-dimensional (3D) DAS vertical seismic profiling data in the Hydrate-01 STW. Temperature surveys were also acquired with the DTS as deployed in the Hydrate-01 STW during the completion of the well and nearly continuously since March-2019.
The interfacial behavior of surfactants exerts a considerable impact on the chemical flooding-produced liquid treatment project. For circumventing the limitations of model simplification and ...single-factor simulation of previous molecular dynamics (MD) studies, this paper based on the experimental results of crude oil-phase and water-phase composition constructed different simulation systems of “crude oil/SDBS/mineral water” considering the concentration of sodium dodecyl benzene sulfonate (SDBS). The impact of SDBS concentration on the stability of the crude oil–mineral water interfacial film was explored, and the simulation results were verified by comparing with the simulation system of “crude oil/SDBS/pure water” and interfacial tension experiments. The simulated results showed that the SDBS molecules in the system exist in the form of a monolayer film after dynamic relaxation equilibrium, and with the increase in concentration, the number of SDBS molecules per unit area of the film increases, and the molecular chain bending characteristics are weakened. The order of the effect of inorganic cations on the aggregation degree of SDBS is Ca2+ > Na+ > K+ > Mg2+. When the concentration of SDBS increased from 0.15 to 0.70 mol/L, the total oil water interfacial film thickness increased from 1.433 nm in the crude oil/SDBS/mineral water system and 1.272 nm in the crude oil/SDBS/pure water system to 2.125 nm in the crude oil/SDBS/mineral water system and 2.398 nm in the crude oil/SDBS/pure water system. The absolute value of interface formation energy increased from 1223.59 and 1236.32 to 2739.19 and 3033.64, respectively, which are also basically consistent with the experimental results of interface tension. Furthermore, inorganic ions will weaken the performance of the surfactant SDBS and detrimentally affect the structural strength and stability of interfacial films. These results offer useful insights into the stabilization mechanism of oil–water emulsions. In particular, they provide a basis for the design and optimization of new pathways for oil–water emulsion instability in oilfield development.
When liquid nitrogen (LN2) comes in contact with the coal seam, the mechanical properties of the coal body will be changed, which can fracture the coal seam and improve the efficiency of coalbed ...methane extraction. To explore the influence of liquid nitrogen on the mechanical properties of dry and saturated coal, this paper adopts different LN2 treatment methods (freezing 0, 50 min, F-T 10 cycles) to determine the mechanical strength of the coal sample and the ultrasonic longitudinal wave velocity. After a single freezing of LN2 for 50 min, the mechanical properties of the dry and saturated frozen coal samples have been improved. The mechanical strength of the saturated frozen coal samples has increased more than that of the dry state; the freeze–thaw cycle reduces the mechanical strength. The compressive strength has the largest decrease, which is reduced by 45.2%; the wave velocity of the dry coal sample shows a trend of first increasing and then decreasing after different LN2 treatments, but the overall change is small. The water-saturated coal sample increases during a single freezing and decreases during the freeze–thaw cycles, and the lowest wave speed is only 0.821 km/s. By analyzing the changes in mechanical properties, it is concluded that water-saturation treatment can damage its own strength. Short-term freezing can help increase the mechanical strength of coal. Freeze–thaw cycles cause serious deterioration and damage to coal. The increase in the pore volume of coal in the freezing stage is much greater than that in the melting stage.
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