354 research outputs found
The Pre-Flood / Flood Boundary: As Defined in Grand Canyon and East Mojave
The singular events which occurred at the initiation of the Flood should have produced a geologic signature with at least five characteristics: 1) A mechanical-erosional discontinuity (ED) identified by regional structural analysis -- probably the most significant unconformity in any given area; 2) A time or age discontinuity (AD) identified by coarse sediments above the erosional unconformity containing lithified fragments of various sedimentary units found below the unconformity; 3) A tectonic discontinuity (TO), found at the erosional unconformity, distinguished by substantial regional tectonic disruption, especially at pre-Flood continental margins; 4) A sedimentary discontinuity (SO) consisting of a thick, fining-upward, clastic-to-chemical strata megasequence of regional to inter-regional extent defined at its base by a significant onlap unconformity; 5) A paleontological discontinuity (PO) marked by an increase in abundance of fossils and the first appearance of abundant plant, animal, and/or fungal fossils.
In Grand Canyon of Arizona one of the most significant regional unconformities (ED) is found at or near the top of the Chuar Group. Associated with the unconformity is the Sixtymile Formation -- a tectonicsedimentary unit dominated by breccia with large clasts (TO) from the formations below it (AD). The Sixtymile Formation occurs at the bottom of a thick, regionally extensive series of strata called the Sauk Sequence, consisting of the fining-upward clastics, capped by carbonates (SO). Only low-abundance microfossils are known below the unconformity, whereas undisputed animal fossils occur only above the Sixtymile Formation, and there in great abundance (PO). We believe, therefore, that the Sixtymile Formation is the oldest preserved Flood deposit in Grand Canyon of Arizona.
In the eastern Mojave Desert region of California, the Kingston Peak Formation is a very thick, regionally extensive clastic unit containing gigantic breccia clasts (TO) from the formations below it (AD). Associated with the formation is one of the region\u27s most prominent unconformities (ED). The Kingston Peak Formation is also the lowermost of a very thick, regionally extensive, transgreSSive, fining-upward, clastic-tocarbonate megasequence (SO) known as the Sauk Sequence. Only low-abundance microfossils are known from the Kingston Peak Formation and below, whereas common animal fossils are only found in rocks above the formation (PO). We believe, therefore, that the Kingston Peak Formation signals the beginning of the Flood in the Mojave region of California and should be correlated with the Sixtymile Formation of Grand Canyon of Arizona
Representational specializations of the hippocampus in phylogenetic perspective
In a major evolutionary transition that occurred more than 520 million years ago, the earliest vertebrates adapted to a life of mobile, predatory foraging guided by distance receptors concentrated on their heads. Vision and olfaction served as the principal sensory systems for guiding their search for nutrients and safe haven. Among their neural innovations, these animals had a telencephalon that included a homologue of the hippocampus. Experiments on goldfish, turtles, lizards, rodents, macaque monkeys and humans have provided insight into the initial adaptive advantages provided by the hippocampus homologue. These findings indicate that it housed specialized map-like representations of odors and sights encountered at various locations in an animal’s home range, including the order and timing in which they should be encountered during a journey. Once these representations emerged in early vertebrates, they also enabled a variety of behaviors beyond navigation. In modern rodents and primates, for example, the specialized representations of the hippocampus enable the learning and performance of tasks involving serial order, timing, recency, relations, sequences of events and behavioral contexts. During primate evolution, certain aspects of these representations gained particular prominence, in part due to the advent of foveal vision in haplorhines. As anthropoid primates—the ancestors of monkeys, apes and humans—changed from small animals that foraged locally into large ones with an extensive home range, they made foraging choices at a distance based on visual scenes. Experimental evidence shows that the hippocampus of monkeys specializes in memories that reflect the representation of such scenes, rather than spatial processing in a general sense. Furthermore, and contrary to the idea that the hippocampus functions in memory to the exclusion of perception, brain imaging studies and lesion effects in humans show that its specialized representations support both the perception and memory of scenes and sequences
Comparison of Uncultured Marrow Mononuclear Cells and Culture-Expanded Mesenchymal Stem Cells in 3D Collagen-Chitosan Microbeads for Orthopedic Tissue Engineering
Stem cell-based therapies have shown promise in enhancing repair of bone and cartilage. Marrow-derived mesenchymal stem cells (MSC) are typically expanded in vitro to increase cell number, but this process is lengthy, costly, and there is a risk of contamination and altered cellular properties. Potential advantages of using fresh uncultured bone marrow mononuclear cells (BMMC) include heterotypic cell and paracrine interactions between MSC and other marrow-derived cells including hematopoietic, endothelial, and other progenitor cells. In the present study, we compared the osteogenic and chondrogenic potential of freshly isolated BMMC to that of cultured-expanded MSC, when encapsulated in three-dimensional (3D) collagen-chitosan microbeads. The effect of low and high oxygen tension on cell function and differentiation into orthopedic lineages was also examined. Freshly isolated rat BMMC (25?106 cells/mL, containing an estimated 5?104 MSC/mL) or purified and culture-expanded rat bone marrow-derived MSC (2?105 cells/mL) were added to a 65?35?wt% collagen-chitosan hydrogel mixture and fabricated into 3D microbeads by emulsification and thermal gelation. Microbeads were cultured in control MSC growth media in either 20% O2 (normoxia) or 5% O2 (hypoxia) for an initial 3 days, and then in control, osteogenic, or chondrogenic media for an additional 21 days. Microbead preparations were evaluated for viability, total DNA content, calcium deposition, and osteocalcin and sulfated glycosaminoglycan expression, and they were examined histologically. Hypoxia enhanced initial progenitor cell survival in fresh BMMC-microbeads, but it did not enhance osteogenic potential. Fresh uncultured BMMC-microbeads showed a similar degree of osteogenesis as culture-expanded MSC-microbeads, even though they initially contained only 1/10th the number of MSC. Chondrogenic differentiation was not strongly supported in any of the microbead formulations. This study demonstrates the microbead-based approach to culturing and delivering cells for tissue regeneration, and suggests that fresh BMMC may be an alternative to using culture-expanded MSC for bone tissue engineering.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140225/1/ten.tea.2013.0151.pd
Catastrophic Plate Tectonics: A Global Flood Model of Earth History
In 1859 Antonio Snider proposed that rapid, horizontal divergence of crustal plates occurred during Noah\u27s Flood. Modem plate tectonics theory is now confiated with assumptions of uniformity of rate and ideas of continental \u27drift\u27. Catastrophic plate tectonics theories, such as Snider proposed more than a century ago, appear capable of explaining a wide variety of data -- including Biblical and geologic data which the slow tectonics theories are incapable of explaining. We would like to propose a catastrophic plate tectonics theory as a framework for earth history.
Geophysically, we begin with a pre-Flood earth differentiated into core, mantle, and crust, with the crust hOrizontally differentiated into sialic craton and mafic ocean floor. The Flood was initiated as slabs of oceanic floor broke loose and subducted along thousands of kilometers of pre-Flood continental margins. Deformation of the mantle by these slabs raised the temperature and lowered the viscosity of the mantle in the vicinity of the slabs. A resulting thermal runaway of the slabs through the mantle led to meters-per-second mantle convection. Cool oceanic crust which descended to the core/mantle boundary induced rapid reversals of the earth\u27s magnetic field. Large plumes originating near the core/mantle boundary expressed themselves at the surface as fissure eruptions and flood basalts. Flow induced in the mantle also produced rapid extension along linear belts throughout the sea floor and rapid horizontal displacement of continents. Upwelling magma jettisoned steam into the atmosphere causing intense global rain. Rapid emplacement of isostatically lighter mantle material raised the level of the ocean floor, displacing ocean water onto the continents. When virtually all the pre-Flood oceanic floor had been replaced with new,less-dense, less-subductable, oceanic crust, catastrophic plate motion stopped. Subsequent cooling increased the density of the new ocean floor, producing deeper ocean basins and a reservoir for post-Flood oceans.
Sedimentologically, we begin with a substantial reservoir of carbonate and clastic sediment in the pre-Flood ocean. During the Flood hot brines associated with new ocean floor added precipitites to that sediment reservoir, and warming ocean waters and degassing magmas added carbonates - especially high magnesium carbonates. Also during the Flood, rapid plate tectonics moved pre-Flood sediments toward the continents. As ocean plates subducted near a continental margin, its bending caused upwarping of sea floor, and its drag caused downwarping 609 of continental crust, facilitating the placement of sediment onto the continental margin. Once there, earthquake induced sea waves with ocean-to-Iand movement redistributed sediment toward continental interiors. Resulting sedimentary units tend to be thick, uniform, of unknown provenance, and extend over regional, inter-regional, and even continental areas.
After the Flood, the earth experienced a substantial period of isostatic readjustment, where local to regional catastrophes with intense earthquake and volcanic activity were common. Post-Flood sedimentation continued to be rapid but was dominantly basinal on the continents. Left-over heat in the new oceans produced a significantly warmer climate just after the Flood. In the following centuries, as the earth cooled, floral and faunal changes tracked the changing climate zonation. The warmer oceans caused continental transport of moisture that led to the advance of continental glaciers and ultimately to the formation of polar ice caps
Hydroxycarboxylic acid receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database
The hydroxycarboxylic acid family of receptors (ENSFM00500000271913, nomenclature as agreed by the NC-IUPHAR Subcommittee on Hydroxycarboxylic acid receptors [32, 10]) respond to organic acids, including the endogenous hydroxy carboxylic acids 3-hydroxy butyric acid and L-lactic acid, as well as the lipid lowering agents nicotinic acid (niacin), acipimox and acifran [47, 54, 57]. These receptors were provisionally described as nicotinic acid receptors, although nicotinic acid shows submicromolar potency at HCA2 receptors only and is unlikely to be the natural ligand [54, 57]
Hydroxycarboxylic acid receptors in GtoPdb v.2023.1
The hydroxycarboxylic acid family of receptors (ENSFM00500000271913, nomenclature as agreed by the NC-IUPHAR Subcommittee on Hydroxycarboxylic acid receptors [36, 12]) respond to organic acids, including the endogenous hydroxy carboxylic acids 3-hydroxy butyric acid and L-lactic acid, as well as the lipid lowering agents nicotinic acid (niacin), acipimox and acifran [53, 60, 65]. These receptors were provisionally described as nicotinic acid receptors, although nicotinic acid shows submicromolar potency at HCA2 receptors only and is unlikely to be the natural ligand [60, 65]
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Long-Term US Industrial Energy Use and CO2 Emissions
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Long-Term Modeling of Wind Energy in the United States
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Novel Calicivirus Identified in Rabbits, Michigan, USA
This virus is distinct from rabbit hemorrhagic disease virus
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