Academic literature on the topic 'KPg boundary'
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Journal articles on the topic "KPg boundary":
1
Liu, Liang, Jin Zhang, Frank E. Rheindt, Fumin Lei, Yanhua Qu, Yu Wang, Yu Zhang, et al. "Genomic evidence reveals a radiation of placental mammals uninterrupted by the KPg boundary." Proceedings of the National Academy of Sciences 114, no. 35 (August 14, 2017): E7282—E7290. http://dx.doi.org/10.1073/pnas.1616744114.
Abstract:
The timing of the diversification of placental mammals relative to the Cretaceous–Paleogene (KPg) boundary mass extinction remains highly controversial. In particular, there have been seemingly irreconcilable differences in the dating of the early placental radiation not only between fossil-based and molecular datasets but also among molecular datasets. To help resolve this discrepancy, we performed genome-scale analyses using 4,388 loci from 90 taxa, including representatives of all extant placental orders and transcriptome data from flying lemurs (Dermoptera) and pangolins (Pholidota). Depending on the gene partitioning scheme, molecular clock model, and genic deviation from molecular clock assumptions, extensive sensitivity analyses recovered widely varying diversification scenarios for placental mammals from a given gene set, ranging from a deep Cretaceous origin and diversification to a scenario spanning the KPg boundary, suggesting that the use of suboptimal molecular clock markers and methodologies is a major cause of controversies regarding placental diversification timing. We demonstrate that reconciliation between molecular and paleontological estimates of placental divergence times can be achieved using the appropriate clock model and gene partitioning scheme while accounting for the degree to which individual genes violate molecular clock assumptions. A birth-death-shift analysis suggests that placental mammals underwent a continuous radiation across the KPg boundary without apparent interruption by the mass extinction, paralleling a genus-level radiation of multituberculates and ecomorphological diversification of both multituberculates and therians. These findings suggest that the KPg catastrophe evidently played a limited role in placental diversification, which, instead, was likely a delayed response to the slightly earlier radiation of angiosperms.
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Rosado, Margarita, Ruslan Gabbasov, and Isaura Fuentes-Carrera. "Numerical Simulations of KPG 302 (NGC 3893/96)." Proceedings of the International Astronomical Union 6, S277 (December 2010): 259–62. http://dx.doi.org/10.1017/s1743921311022903.
Abstract:
AbstractWe present the results of numerical simulations on the M51-type galaxy pair KPG 302 (NGC 3893/96) taking as boundary conditions for these simulations the results of our observations on the kinematics of this pair. The observations allow us to deduce the different components of each galaxy in the pair (stellar disk and bulge, dark matter halo) as well as the geometry of the encounter at the present time. The numerical simulations were carried out using GADGET2 numerical code including gas. We describe in detail how the numerical simulations are being done. We succeeded to reproduce the actual conditions of the pair, in particular, the grand-design spiral arms of NGC 3893 (the main galaxy of the pair) when the numerical simulations include gas, consider a parabolic direct collision and multiple passages.
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DePalma, Robert A., Jan Smit, David A. Burnham, Klaudia Kuiper, Phillip L. Manning, Anton Oleinik, Peter Larson, et al. "A seismically induced onshore surge deposit at the KPg boundary, North Dakota." Proceedings of the National Academy of Sciences 116, no. 17 (April 1, 2019): 8190–99. http://dx.doi.org/10.1073/pnas.1817407116.
Abstract:
The most immediate effects of the terminal-Cretaceous Chicxulub impact, essential to understanding the global-scale environmental and biotic collapses that mark the Cretaceous–Paleogene extinction, are poorly resolved despite extensive previous work. Here, we help to resolve this by describing a rapidly emplaced, high-energy onshore surge deposit from the terrestrial Hell Creek Formation in Montana. Associated ejecta and a cap of iridium-rich impactite reveal that its emplacement coincided with the Chicxulub event. Acipenseriform fish, densely packed in the deposit, contain ejecta spherules in their gills and were buried by an inland-directed surge that inundated a deeply incised river channel before accretion of the fine-grained impactite. Although this deposit displays all of the physical characteristics of a tsunami runup, the timing (<1 hour postimpact) is instead consistent with the arrival of strong seismic waves from the magnitude Mw∼10 to 11 earthquake generated by the Chicxulub impact, identifying a seismically coupled seiche inundation as the likely cause. Our findings present high-resolution chronology of the immediate aftereffects of the Chicxulub impact event in the Western Interior, and report an impact-triggered onshore mix of marine and terrestrial sedimentation—potentially a significant advancement for eventually resolving both the complex dynamics of debris ejection and the full nature and extent of biotic disruptions that took place in the first moments postimpact.
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Bininda-Emonds, Olaf R. P., and Andy Purvis. "Comment on “Impacts of the Cretaceous Terrestrial Revolution and KPg Extinction on Mammal Diversification”." Science 337, no. 6090 (July 5, 2012): 34.1–34. http://dx.doi.org/10.1126/science.1220012.
Abstract:
Meredith et al. (Reports, 28 October 2011, p. 521) question three findings of our delayed-rise hypothesis for present-day mammals made with reference to the Cretaceous-Paleogene (KPg) boundary, based on their new time tree of the group. We show that their own data do not support their objections and that the macroevolutionary patterns from the respective phylogenies are not statistically different.
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Baas, Pieter, Steven R. Manchester, Elisabeth A. Wheeler, and Rashmi Srivastava. "Fossil wood with dimorphic fibers from the Deccan Intertrappean Beds of India – the oldest fossil Connaraceae?" IAWA Journal 38, no. 1 (February 13, 2017): 124–33. http://dx.doi.org/10.1163/22941932-20170162.
Abstract:
Wood of Connaroxylon dimorphum (Connaraceae, Oxalidales) from the Deccan Intertrappean Beds of India (KPg Boundary 65–67 MY BP) is described. It is characterized by parenchyma-like fiber bands alternating with normal fibers, septate and nonseptate fibers, vessel-ray pits with strongly reduced borders, uniseriate rays of square and upright cells, and radial tubules in the center of ray cells that are arranged in a herringbone pattern. The overall wood anatomy strongly resembles Melastomataceae p. p., Lagerstroemia p. p. (Lythraceae) and Connarus (Connaraceae). However, the shared radial tubules of Connarus and the fossil strongly tilt the evidence of botanical affinities towards this genus. This would represent the second and by far the oldest fossil wood record of the Connaraceae, also considerably older than the earliest fossil records of the family’s other plant parts, and one of the oldest fossils of the order Oxalidales.
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Maruoka, Teruyuki, Yoshiro Nishio, Tetsu Kogiso, Katsuhiko Suzuki, Takahito Osawa, Yuichi Hatsukawa, and Yasuko Terada. "Enrichment of chalcophile elements in seawater accompanying the end-Cretaceous impact event." GSA Bulletin 132, no. 9-10 (February 5, 2020): 2055–66. http://dx.doi.org/10.1130/b35403.1.
Abstract:
Abstract Chalcophile elements are enriched in the Cretaceous–Paleogene (KPg) boundary clays from Stevns Klint, Denmark. As the concentrations of Cu, Ag, and Pb among several chalcophile elements such as Cu, Zn, Ga, As, Ag, and Pb are correlated with those of Ir, we suggest that these elements were supplied to the oceans by processes related to the end-Cretaceous asteroid impact. Synchrotron X-ray fluorescence images revealed that Cu and Ag exist as trace elements in pyrite grains or as 1–10-µm-sized discrete phases specifically enriched in Cu or Ag. The difference in carrier phases might depend on the materials that transported these elements to the seafloor. Based on their affinities with Cu, Ag, and Ir, iron oxides/hydroxides and organic matter were identified as the potential carrier phases that supplied these elements to the seafloor. Chalcophile elements adsorbed on iron oxides/hydroxides might have been released during reductive dissolution of iron oxides/hydroxides and incorporated into the pyrite produced simultaneously with the reductive dissolution of iron oxides/hydroxides. Both iron oxides/hydroxides and chalcophile elements were possibly released from the KPg target rocks (i.e., sedimentary rocks and/or basement crystalline rocks) by impact heating. Elements with a high affinity to organic matter would have been released upon its degradation and then converted into discrete minerals because of the deficiency in Fe ions. As such discrete minerals include the elements that form acid soluble sulfides such as Cu, Ag, and Pb, enrichment of these elements might have been induced by the intense acid rain just after the end-Cretaceous asteroid impact.
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Umbarger, Keelan F., and John W. Snedden. "Delineation of post-KPg carbonate slope deposits as a sedimentary record of the Paleogene linkage of De Soto Canyon and Suwannee Strait, northern Gulf of Mexico." Interpretation 4, no. 1 (February 1, 2016): SC51—SC61. http://dx.doi.org/10.1190/int-2015-0086.1.
Abstract:
Seismicity generated from the Chicxulub impact has been postulated as the cause for the dramatic alteration of basin margin morphology and catastrophic movement of sediments in the Gulf of Mexico (GOM). Immediately following the impact, the formation of the Cretaceous-Paleogene boundary deposit (KPBD) was widespread and caused considerable erosion as portions of the Florida Escarpment collapsed, inducing sediment failure on the northern Florida Platform and formation of the ancestral De Soto Canyon. Overlying the more prominent KPBD existed a distinct, younger, post-Cretaceous/Paleogene carbonate slope deposit (CSD) confined within the De Soto Canyon bathymetric feature. Presence of this discrete unit provided insight into the post-impact history of De Soto Canyon and its long-duration connection to the Suwannee Strait, which linked the GOM with the Atlantic Ocean for almost 40 ma. We have postulated that the bathymetric low of the De Soto Canyon acted as a conduit for west to east sediment movement from nearby carbonate-dominated shorelines into the canyon in episodic sediment transport events from the Danian to the earliest Miocene. Closure of the Suwannee Strait, due to sediment infilling, terminated deposition of the De Soto Canyon CSD. This was followed by major siliciclastic influx as the paleo-Tennessee drainage system began to enter the Mississippi Canyon area.
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Breiter, Karel, Jaromír Tvrdý, and Pavel Jedlička. "Petrological diversity of leucocratic rocks at the sodium-potassium feldspar deposit Krásno – Vysoký kámen." Geoscience Research Reports 56, no. 1 (May 9, 2023): 14–20. http://dx.doi.org/10.3140/zpravy.geol.2023.03.
Abstract:
The presented study aims to reevaluate the geological structure of the Krásno-Vysoký Kámen feldspar deposit and its relationship to the surrounding rocks using chemical and imaging methods. For this purpose, we have documented in detail all the preserved fragments of drill cores from the survey in the 1960s and 1970s years, and 21 exploratory boreholes of the KP series (Fig. 1) realized in 2021, including about 600 chemical XRF bulk-rocks analyzes of rocks from these drillings. The Krásno-Vysoký Kámen open pit is located about 1 km northwest of the Krásno village, western Bohemia. Subject of mining is a complex of leucocratic, feldspar-rich granitoids consisting of predominant medium-grained leucogranite with mainly subhorizontal intercalations of syenite, aplite-pegmatite and feldspar-rich metasomatites. Both the immediate bedrock and the exposed overburden of the leucogranite complex consist of biotite granites. The leucogranite complex forms a lenticular body, the lower boundary of which decreases from N and NW towards E and S (Fig. 5). Especially on the western side of the open pit, the contact of the two rocks is relatively steep, further to the east it flattens. Medium-grained leucocratic granite makes up most of the volume of the deposit. It has a magmatic texture (Fig. 2a) with euhedral, short columnar albite crystals, subhedral orthoclase grains, irregular late quartz grains and low mica content (Tab. 2); apatite and rare topaz and niobium rutile are also present. In the SW edge of the quarry, contact facies of the leucogranite with several layers of oriented crystallization of quartz is exposed. Locally, leucogranite changes to leucosyenite (Fig. 2b). The leucosyenite is still a medium-grained rock with a magmatic texture, but the quartz content decreases (<10%) and the mica is only accessory. Several flat veins of virtually mica-free aplite (Fig. 2c), from several dm to 5 m thick, are lined along the upper contact by a zone of oriented K-feldspar and quartz crystallization (i.e. stockscheider). Alkaline metasomatites (Fig. 2d) are medium to fine grained. Medium-grained varieties are macroscopically hardly distinguishable from igneous syenites; fine-grained varieties are similar to aplites. Feldspars in metasomatites already have a completely irregular worm-like shape, while the ratio of both feldspars fluctuates strongly. The underlying biotite granite is currently well exposed in the NW part of the quarry and was reached by wells KP4, KP5, KP6, and KP7. It is medium-grained granite with Li-biotite and topaz. The contact between this granite and the overlying leucocratic complex was interpreted as rapid transition in old boreholes (Pácal and Pavlů 1979), but sharp contact was found in the borehole KP4. The overlying biotite granite was exposed in the SW parts of the quarry and confirmed by 2 boreholes (KP2, KP3). Both types of biotite granite differ statistically in Fe, Na and K contents. The medians of the chemical composition of all rock types defined above are shown in Tab. 3, relationships between some elements in Fig. 3. While both types of biotite granites and aplite have a relatively homogeneous chemical composition, the composition of leucogranite, syenite and metasomatites is very variable, especially in terms of SiO2 and alkalis. When comparing both alkalis, a significantly greater variability of K2O contents (<1 to 9 wt. %) compared to Na2O (mostly 1-6 wt. %, but fewer samples with marginal values) is evident. Extreme samples containing almost only one of the feldspars can be found in the case of syenite, metasomatites and leucogranite. The total content of feldspars varies mainly between 40 and 70 wt. % in leucogranite, 70–90 wt. % in syenite, 50–70 wt. % in aplite and 50–90 wt. % in metasomatites. Significant vertical changes in the chemistry of macroscopically homogeneous leucocratic rocks are well documented in boreholes KP13 and KP14 (Fig. 4).
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Al Ahmar, Rudy, and Joseph Majdalani. "On the Kármán momentum-integral approach and the Pohlhausen paradox: Extension to a cylinder in crossflow with a potential farfield motion." Physics of Fluids 34, no. 6 (June 2022): 063107. http://dx.doi.org/10.1063/5.0096780.
Abstract:
In this work, the Kármán–Pohlhausen (KP) momentum-integral approach based on optimized fourth-order (MX4) polynomial approximations of the velocity and temperature profiles is applied to a classical benchmark problem, namely, that of a cylinder in crossflow with a variable pressure gradient. This enables us to extract closed-form expressions for both hydrodynamic and thermal boundary-layer parameters and then compare the newly found solutions to their counterparts obtained using Pohlhausen's cubic (KP3) and quartic (KP4) polynomials. As usual, the farfield around the cylinder is modeled using potential flow theory and the momentum-integral analysis is paired with Walz's empirical expression for the momentum thickness, which is based on a wide collection of experiments. This procedure permits retrieving explicit relations for the pressure-sensitive KP3, KP4, and MX4 velocity profiles across the boundary layer; one also obtains accurate approximations for the pressure distribution around the cylinder as well as an improved prediction of the separation point, namely, to within 0.87% of the actual location. In this process, refined estimates are produced for several characteristic parameters whose distributions are found to be in favorable agreement with experimental measurements and numerical simulations. These include the disturbance, momentum, and displacement thicknesses as well as the skin friction, pressure, and total drag coefficients. Finally, the thermal analysis is undertaken using both isothermal and isoflux boundary conditions. For each of these cases, closed-form analytical solutions are obtained for the local Nusselt number distribution around the cylinder, and these distributions are found to exhibit noticeably reduced errors relative to their classical values.
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Sarajedini, Ata. "The Formation Chronology of Local Group Spiral Galaxies." Symposium - International Astronomical Union 207 (2002): 73–82. http://dx.doi.org/10.1017/s0074180900223401.
Abstract:
The ‘Second Parameter Effect’ (2ndPE) has long been recognized as an important probe into the formation of spiral galaxies. The concept that the horizontal branch morphologies of globular clusters are primarily affected by metal abundance in the inner halo (RGC<8 kpc) of the Galaxy but require an additional parameter (probably cluster age) to explain their behavior in the outer halo (RGC > 8 kpc), suggests that the former experienced a rapid monotonic collapse while the latter underwent a slower chaotic formation scenario. As such, in the Milky Way, the so-called second parameter boundary is located at 8 kpc. We find that, in the other Local Group spirals — M31 and M33 — this boundary lies at ∼40 kpc and ∼0 kpc, respectively. We therefore speculate that the boundary delimiting rapid monotonic halo collapse from the chaotic accretion of dwarf galaxy fragments is inversely related to the mass of the spiral galaxy.
Dissertations / Theses on the topic "KPg boundary":
1
Turner, Bryan William. "Testing the local diachroneity of the terrestrial lithostratigraphic KPg Boundary, Northern Montana." Thesis, Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/turner/TurnerB0510.pdf.
Abstract:
The lithostratigraphic KPg boundary separating the underlying Cretaceous Hell Creek Formation from overlying strata of the Paleogene Fort Union Formation in north-central Montana is delineated at the lowermost coal (Z-coal) at the base of the Fort Union. Since meandering stream floodplain coals record deposition in areally-restricted, meanderbelt environments, the lithostratigraphic KPg boundary is diachronous. To test this assertion, a chronostratigraphic framework, developed using radiometrically dated (â´â° Ar-³⹠Ar) ash horizons, is utilized to examine the physical stratigraphic relations between strata of the uppermost Hell Creek and lowermost Fort Union Formations. The uppermost (3m) Hell Creek Formation consists of massive mudrock with sporadic coal stringers. The lowermost (3m) Fort Union Formation consists of massive mudrocks with the discontinuous Z-coal at its base. No sedimentary structures are present. Three ash horizons, distinguished in the field by color and mineralogy, were used to establish correlations. The lower and middle ashes have been dated at 65.00 ± 0.05 Ma and 64.95 ± 0.05 Ma, respectively (Swisher et al., 1993). Six sites are studied. From east to west, these are: Mossbrucker, Lerbekmo, Pearl, Bone Hollow, Hell's Hollow, and Nirvana. Each site was trenched 3 meters above and below the Z-coal and lithofacies described every centimeter. The lithostratigraphic boundary at Lerbekmo is 55cm below the chronostratigraphic framework, 56 cm below at Mossbrucker, 9 cm above at Pearl, 258 cm below at Nirvana, and was not preserved at Bone Hollow and Hell's Hollow. Wheeler diagrams of these sections suggest the Z-coal is stratigraphically lower in the west and higher in the eastern sections. These observations demonstrate that the lithostratigraphic KPg boundary is diachronous implying portions of the Hell Creek are Paleogene in age and portions of the Fort Union Cretaceous in age. Furthermore, this demonstrates that lithostratigraphy provides insufficient constraints on determining chronostratigraphic position. Localized lithostratigraphic correlations of the terrestrial sections are also complicated by subtle diastems. Since floodplain deposition is centralized in the floodplain trough (Pizzuto et al., 2008) and a single flood event has limited areal extent (Aalto et al., 2003), the precision of lithostratigraphic correlations is limited without a chronostratigraphic framework of isochronous event beds.
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Jouini, Arbia. "Perturbations biogéochimiques à la limite Crétacé-Paléogène : apport des isotopes du Soufre et du Calcium." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0065.
Abstract:
La limite Crétacé-Paléogène (KPg, -66 Ma) est associée à l'une des plus grandes perturbations environnementale de l'histoire récente de la Terre. Cette crise, liée à la mise en place d'une province magmatique de premier ordre (traps du Deccan) et/ou à un impact météoritique (formation du cratère de Chixculub) se traduit entre autres par une perturbation profonde de la bioproduction carbonatée océanique. Si de nombreuses questions subsistent quant à l'importance relative de l'impact et du volcanisme dans les perturbations de la limite KPg, la modification de la composition chimique du système océan-atmosphère par l'émission d'énormes quantités d'acide sulfurique et carbonique d'origines volcaniques a probablement joué un rôle clé dans la crise Crétacé-PaléogèneDurant ce projet de thèse j'ai réalisé des enregistrements isotopiques à haute résolution des isotopes stables du soufre et du calcium à travers la transitons Crétacé-Paléogène. Ces enregistrements sont basés sur des échantillons monospécifiques de foraminifères planctoniques et benthiques issue du pacifique équatorial.Les enregistrements de δ44/40Ca benthiques et planctoniques avant et après la limite K-Pg nous ont permis de mettre en évidence une succession d'épisodes de changements de l'alcalinité océanique liés à l'augmentation de l'altération continentale et à la crise de biocalcification causée par les émissions de CO2 du volcanisme du Deccan. La compensation des carbonates par la dissolution des sédiments carbonatés, la réduction de la biocalcification et/ou l'augmentation de l'altération continentale ont dû se produire pour compenser l'excès de CO2. Par conséquence, cela a entraîné des changements rapides dans la chimie des carbonates océaniques, en combinaison avec une réduction de l'exportation de l'alcalinité de surface en réponse à la crise de biominéralisation planctonique du Paléogène précoce.L'examen de la perturbation du cycle du soufre quant lui, soutient plutôt l'idée que l'extinction de masse à travers la transition K-Pg n'est pas être associée à une expansion globale de conditions anoxique, contrairement aux différents événements d'extinction de masse du Phanérozoïque, où il existe des preuves multiples du de développement de condition anoxique associé aux perturbations du cycle du carbone. Ces conclusions est en accord avec les observations micropaléontologiques qui ne montrent pas d'extinction de masse des foraminifères benthiquesCette approche géochimique multiproxies a l'avantage de permettre donc une évaluation plus pousser de certains paramètres clés tel que la chimie des carbonates et l'anoxie océanique à travers la transition Crétacé -Paléogène permettant ainsi d'avoir un schéma global plus clair des perturbations biogéochimiques autour de cette périodeThe Cretaceous-Paleogene boundary (KPg, -66 Ma) is associated to one of the deepest biogeochemical cycle disruptions in Earth's recent history. The events associated to the KPg boundary include one of the strongest known oceanic calcareous bioproduction crisis and are coeval with a bolid impact (that formed the Chixculub crater) and the emplacement of a Large Igneous Province (Deccan traps). Many studies investigated the mechanism(s) triggering the environmental perturbations and many questions remain unanswered regarding the relative contribution of the volcanic event and the impact on the KPg crisis. Yet, modification of the ocean-atmosphere system composition through massive input of sulfuric and carbonic acid very likely played a key, underconstrained, role.During this thesis project, I conducted high-resolution stable sulphur and calcium isotope records across the Cretaceous-Paleogene transition. These records are based on monospecific samples of planktonic and benthic foraminifera from the equatorial Pacific.The benthic and planktonic δ44/40Ca records before and after the K-Pg boundary allowed us to demonstrate a succession of episodes of ocean alkalinity change related to the increase in continental weathering and the biocalcification crisis caused by CO2 emissions from Deccan volcanism. Carbonate compensation through dissolution of carbonate sediments, reduction of biocalcification and/or increase in continental weathering had to occur to compensate for the excess CO2. As a result, this led to rapid changes in oceanic carbonate chemistry, in combination with a reduction in the export of surface alkalinity in response to the early Paleogene planktonic biomineralisation crisisExamination of sulphur cycle disruption instead supports the idea that mass extinction through the K-Pg transition is not associated with a global expansion of anoxic conditions, in contrast to the various Phanerozoic mass extinction events, where there are multiples evidences for the development of anoxic conditions associated with carbon cycle disruption. These findings are consistent with micropalaeontological observations that show no benthic foraminiferal mass extinction.This multi-proxy geochemical approach has the advantage of allowing a more detailed assessment of key parameters such as carbonate chemistry and oceanic anoxia across the Cretaceous-Paleogene transition, thus providing a clearer global picture of biogeochemical perturbations around this time
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El-Hachem, Maud. "Mathematical models of biological invasion." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/232864/1/Maud_El-Hachem_Thesis.pdf.
Abstract:
This thesis studies mathematical models of a population of cells invading the surrounding environment or another living population. A classical single-species model is reformulated using a moving boundary to track the position of the moving front of the invading population. The moving boundary is also used to separate two populations. Other models studied are coupled partial differential equations to describe the interaction of a population with another one. Different types of interaction are represented: the degradation of healthy skin by cancer and the growth of bone tissue on substrate.
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Risius, Steffen. "Development of a time-resolved quantitative surface-temperature measurement technique and its application in short-duration wind tunnel testing." Thesis, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E44D-A.
Book chapters on the topic "KPg boundary":
1
Smit, J. "The KPg boundary Chicxulub impact-extinction hypothesis: The winding road towards a solid theory." In From the Guajira Desert to the Apennines, and from Mediterranean Microplates to the Mexican Killer Asteroid: Honoring the Career of Walter Alvarez. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.2557(19).
Abstract:
ABSTRACT Along with the origin of life, the quest for the ultimate cause of the end of the dinosaurs and ~72% of other species is one of the most publicized questions in the history of our planet. So, it probably should not have come as a surprise that when Walter Alvarez and his team launched the impact-extinction theory, the opposition and the resistance against the theory was strong from the beginning and continues up to the present day. This paper follows the winding road around the roadblocks that were set up against the theory and how both the opposition against and accumulation of new data, e.g., the finding of the Chicxulub impact structure and extraterrestrial Cr isotope ratios to further develop the theory, went hand in hand. Often the roadblocks were overcome, but new ones were set up, and in the struggle to surmount these, the proponents were forced to look back on their arguments, to carefully re-formulate their viewpoints, and to check whether tunnel-vision had developed that might prevent seeing the data available in a different light. However, looking back on the competition among proponents and opponents 40 years later, the impact-extinction theory is stronger than ever before. It has survived and matured from a hypothesis into a well-established theory, although many questions remain to be solved.
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Arz, José A., I. Arenillas, J. M. Grajales-Nishimura, C. L. Liesa, A. R. Soria, R. Rojas, T. Calmus, and V. Gilabert. "No evidence of multiple impact scenario across the Cretaceous/ Paleogene boundary based on planktic foraminiferal biochronology." In From the Guajira Desert to the Apennines, and from Mediterranean Microplates to the Mexican Killer Asteroid: Honoring the Career of Walter Alvarez. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.2557(20).
Abstract:
ABSTRACT Large bolide impacts seem to have strongly affected biological evolution, causing detrimental effects on the biosphere. The best-known case is the Chicxulub impact (Yucatan Peninsula, Mexico), the most probable trigger of the Cretaceous/Paleogene boundary (KPB) mass extinction. Nevertheless, after four decades of intensive research, a consensus on the causal relationship between the impact and the mass extinction has not yet been reached. Most of the scientific community has established multiple, strong arguments for the Chicxulub impact as the most likely and principal cause of the KPB mass extinction. However, a variety of hypotheses link the mass extinction mainly to the volcanism of the Deccan Traps and one or more bolide impact events within a relatively short time through the KPB: one impact in the late Maastrichtian (66.3 Ma), corresponding to the Chicxulub impact, a larger one at the KPB (66 Ma), and a final one in the early Danian (65.9 Ma). Here, we report on the controversies relating to the correlation of the Chicxulub impact event with the mass extinction, with a focus on the stratigraphy and biostratigraphy of sections in Mexico, Cuba, and Haiti, which include ejecta-rich clastic deposits linked to the Chicxulub impact. High-resolution biostratigraphy and quantitative data with planktic foraminifera reveal that these deposits are synchronous with the ejecta-rich airfall layer and the KPB mass extinction horizon of the El Kef, Tunisia, stratotype. Our results provide no support for a multiple impact scenario but confirm that the Chicxulub impact event is indeed the KPB impact event. Furthermore, we have not found any biostratigraphic evidence to support an additional Danian impact event near the Gulf of Mexico region.
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Newnham, Robert E. "Acoustic waves II." In Properties of Materials. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780198520757.003.0026.
Abstract:
Acoustic impedance, acoustic losses, acoustic waves in piezoelectric solids, and surface waves are discussed in this chapter, along with a number of nonlinear acoustic phenomena. The reflection and transmission of acoustic waves across a boundary is governed by acoustic impedance. One of the most important boundary value problems in acoustics concerns a plane wave incident upon a planar surface, dividing one medium from another. In the general case of an anisotropic medium, the incident beam consists of three waves (one quasilongitudinal, two quasitransverse), each traveling at a different velocity. Each of the three incident waves will be refracted and reflected at the boundary. If the second medium is also anisotropic, each incident wave will generate three reflected waves and three refracted waves, a total of 27 waves in all. Wave propagation in a polycrystalline solid where there are many grain boundaries becomes very complicated. The simpler case of a pure longitudinally-polarized wave at normal incidence to the boundary provides insight into the more general problem. In this case the reflection and transmission coefficients are governed by the relatively simple acoustic impedance parameter (ρc)1/2 = ρv, where ρ is the density, c the stiffness coefficient, and v the phase velocity. The reflection coefficient R at the interface between medium I and medium II is The MKS unit for acoustic impedance is the Rayl (=kg/m2 s). Atypical value for a solid is about 107 rayls. In many acoustic applications it is desirable to reduce reflection by matching the acoustic impedance of the two media. Lithium tantalate transducers are well-matched to iron, for example. Sound transmission from the transducer to the medium can be enhanced with composite materials or with graded coupling layers. Backing materials are often selected to promote reflection. In this case acoustic impedances are mismatched. Tungsten and air are two commonly used backing materials. In an isotropic material the acoustic impedance is (ρc11)1/2 for longitudinal waves and (ρc44)1/2 for shear waves. For anisotropic materials the wave velocities and acoustic impedance change with direction as indicated earlier.
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Alanis-Ramírez, Claudia Ivett, Liliana Ávila-Cordoba, Rubi Romero-Romero, and Reyna Natividad. "Biodiesel production as an alternative to reduce the environmental impact of University food courts." In CIERMMI Women in Science Engineering and Technology TXV, 37–50. ECORFAN, 2021. http://dx.doi.org/10.35429/h.2021.6.37.50.
Abstract:
The objective of this work was to assess the environmental impacts of producing biodiesel by heterogeneous and homogeneous catalysis. The raw material for the process was the waste cooking oil (WCO) generated at 27 food courts of Autonomous University of the State of Mexico. The study was conducted by applying Life Cycle Assessment methodology and the environmental impacts were calculated with the SimaPro 9.1.0.11 PhD software with the Ecoinvent database. The method was CML-IA base line C3.06/EU25. The assessed impact categories were: Abiotic Depletion Potential (ADP, elements), Abiotic Depletion Potential (ADP, fossil fuels), Global Warming Potential (100 years) (GWP), Ozone Layer Depletion (ODP), Human Toxicity (HT), Freshwater Aquatic Ecotoxicity (FWAE), Marine Aquatic Ecotoxicity (MAE), Terrestrial Ecotoxicity (TE), Photochemical Oxidation (PO), Acidification (A) and Eutrophication (E). In addition, end point environmental indicators were also calculated (Ecosystems Quality, Human Health Damage and Resources Availability) by the method ReCiPe 2016 Endpoint (H) V1.04 / World (2010) H/A. The system boundary enclosed three main stages, WCO collection, pre-treatment and reaction (to produce biodiesel). It was concluded that the reaction stage is the one with the highest environmental impact. In this sense, the highest impact categories were ADP (fossil fuels) (105.56 MJ), GWP (8.91 kg CO2 eq) and MAE (2387.89 kg 1, 4-DB eq). Nevertheless, it was also found that the GWP for the heterogeneous process is 82.52 % lower than that calculated for the homogeneous process. In addition, the human health damage of the homogeneous process is 1.77 points and is higher than the observed with the heterogeneous process.
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Davison, Sydney G., and Maria Stęślicka. "Electrons at Crystal Surfaces." In Basic Theory of Surface States, 46–60. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198519904.003.0003.
Abstract:
Abstract Since crystals in their natural state are finite, i.e., limited by surfaces, the question arises as to how the energy spectrum of an electron propagating in a finite crystal differs from that in an infinite one. The partial answer is provided by using the Born-von K árm án (1912, 1913) boundary condition (2.138), which shows that, if a finite crystal of N atoms is cut from an infinite one, then the previous continuous allowed band becomes a sequence of N discrete levels (2.141). Clearly, this is not a big difference, if the crystal (i.e., N) is very large. However, there is another important consequence of taking the crystal size into account, namely, that the presence of the surface produces discrete energy levels, which lie in the FEG regions that are inaccessible to electrons in infinite crystals. Tamm (1932) was the first to demonstrate the existence of these surface states by terminating the KP potential as a means of representing the surface. Because of the importance of Tamm’s work in establishing the new idea of surface states, we shall now briefly discuss his findings.
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"Pollution of the Atmosphere." In Environmental Toxicology, edited by Sigmund F. Zakrzewski. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195148114.003.0015.
Abstract:
The earth’s atmosphere consists of 78% (by volume) of N2; 21% O2; about 0.033% CO2; trace amounts of noble gases, NOx, and CH3; and variable amounts of water vapor. At sea level, the amount of water vapor may vary from 0.5 g per kg of air in polar regions to more then 20 g per kg in the tropics. The standard atmosphere is a theoretical set of data that serves as a reference point for calculation of atmospheric changes due to the weather. The values are calculated for sea level conditions and correspond to a pressure of 760 mm of mercury (92.29 in., 1013.25 mbar), an air density of 1.22 kg/m3, and a temperature of 15°C (59 °F). The composition of the air within the troposphere, which is the lowest layer of the atmosphere, does not change with altitude; however, the pressure and temperature decrease with altitude. The relationship between altitude and pressure in the standard atmosphere is shown in Figure 10.1, and the relationship between altitude and temperature is shown in Figure 10.2. The rate of decrease of temperature with altitude (6.49 °C per km) is referred to as the ‘‘standard lapse rate’’. This rate is a strictly theoretical average value because the actual lapse rate varies depending on the weather. Because the air density is proportional to the pressure and inversely proportional to the temperature, it changes at the same rate as the pressure does. The atmosphere is divided into troposphere, stratosphere, mesosphere, and ionosphere. As shown in this figure, the division is based on temperature inversions that occur at the higher altitudes; the altitudes of these inversions vary with the season and with the geographic latitude. Although the general shape of the curves remains the same for all latitudes, the altitudes of the inversions are higher over the equator and lower over the poles; the curves presented in Figure 10.3 refer to middle latitudes. The boundary areas at each temperature inversion are called tropopause, stratopause, and mesopause, respectively. Pollution of the atmosphere is generally the least appreciated of all environmental issues.
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Motzer, William E., and David A. Mustart. "Mount Diablo mercury deposits." In Regional Geology of Mount Diablo, California: Its Tectonic Evolution on the North America Plate Boundary. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.1217(03).
Abstract:
ABSTRACT The California Coast Ranges mercury deposits are part of the western North America mercury belt, in which mercury occurs most commonly as red cinnabar (α-HgS), sometimes associated with its high-temperature polymorph, metacinnabar (β-HgS). In the Coast Ranges, ores were deposited from hydrothermal solutions and range in age from Miocene to Holocene. Ore deposition at Mount Diablo generally occurred along active faults and associated extension fractures in the Franciscan complex, most often in serpentinite that had been hydrothermally altered to silica-carbonate rock. The Mount Diablo mine lies ~48 km (~30 miles) northeast of San Francisco in Contra Costa County and is mineralogically unique in California, because metacinnabar, the higher-temperature polymorph of mercury sulfide, is a major primary ore mineral in the deposit, while at all other mercury mines in California, it is quite rare. In addition, hydrothermal activity is so recent that sulfurous gases and methane continued to be released into the mine at least into the 1940s. Historically, long before active large-scale mining began in the 1800s, the Mount Diablo mercury deposits were known to the Indigenous people of the Ohlone tribes, who used the cinnabar in rituals as well as for red pigment to decorate their bodies, and as a prized trade item. The deposit was later rediscovered in 1863 and mined intermittently until 1958. The Mount Diablo mine and adjacent Rhyne (also variously spelled Ryne or Rhine) mine were the sites of most of the mercury operations in the region, and at both mines, mercury ore occurs in structurally controlled lenticular bodies of silica-carbonate rock and serpentinite. The total district production probably exceeded 12,300 flasks (at 76 pounds or ~34.5 kg per flask) at an estimated grade of 2711 g per metric ton. Low-grade ore reserves are believed to still exist, with 17,000 short tons of indicated and inferred ore. Other minor deposits of copper, silver, and gold occur on Mount Diablo, principally in and around Eagle Peak, but mercury is not associated with these deposits.
Conference papers on the topic "KPg boundary":
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Petersen, Sierra, Allison Curley, Stewart Edie, Rachel Mohr, Elizabeth Oliphant, and Thomas Tobin. "Survivorship vs. Extinction at the KPg Boundary: An isotopic look at vital effects in bivalves." In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.4755.
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Godoy, Derek, Frankie Gutierrez, Samantha Davies, George E. Phillips, Corinne Myers, Sierra Petersen, and Carlie Pietsch. "FUNCTIONAL ECOLOGY OF MARINE INVERTEBRATES ACROSS THE END-CRETACEOUS FROM A NEW SHALLOW SHELF KPG BOUNDARY SITE IN NORTHERN MISSISSIPPI." In GSA Connects 2023 Meeting in Pittsburgh, Pennsylvania. Geological Society of America, 2023. http://dx.doi.org/10.1130/abs/2023am-395036.
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Smit, Jan, Robert A. DePalma, Mark Richards, Walter Alvarez, David A. Burnham, and Phillip L. Manning. "TANIS, A MIXED MARINE-CONTINENTAL EVENT DEPOSIT AT THE KPG BOUNDARY IN NORTH DAKOTA CAUSED BY A SEICHE TRIGGERED BY SEISMIC WAVES OF THE CHICXULUB IMPACT." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-305713.
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HELMINCK, G. F. "SPACES OF BOUNDARY VALUES RELATED TO A MULTIPOINT VERSION OF THE KP-HIERARCHY." In Proceedings of the Fifth International Workshop. WORLD SCIENTIFIC, 2004. http://dx.doi.org/10.1142/9789812702562_0016.
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Patel, Nikhil, and Darren D. Schmidt. "Biomass Boundary Layer Turbine Power System." In 2002 International Joint Power Generation Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ijpgc2002-26035.
Abstract:
A “Boundary Layer Turbine” (BLT), with a specially designed multiple-disk rotor consisting of a number of closely packed parallel disks fixed to the shaft, was used to demonstrate direct conversion of biomass for small-scale distributed power generation. The turbine operates under the effect of skin friction drag exerted on the parallel plates, resulting from the flow of hot gases between the parallel plates. This concept is well known for its resistance to erosion when pumping viscous fluids, and the technology has been developed for commercial pump applications but not for a turbine. The turbine based on this concept is capable of encountering particle-laden gas and can accept ash-containing biomass fuels. In the present experiments, wood-derived sawdust (particle size ∼1 mm) and natural oats were fired separately as the test fuels. These fuels were injected directly into the stream of vitiated hot air downstream of the combustor. The location of injection was based on a 1- to 3-second residence time for complete combustion. This paper discusses a performance study and assessment of deposition, erosion, and corrosion (DEC) effects on the working components of the BLT. The potential for cost-effective electricity production from biomass in distributed-generation applications is also explored. The BLT was operated for 40 hours, consuming 68 kg of biomass fuel. The testing included initial firing of 10% biomass (by heating value), increasing to 100%. Documented performance shows isentropic turbine efficiencies of 11% at 3.2 kW and 6284 rpm. Turbine inlet conditions averaged 2.8 bar and 645 K. Over the course of testing, no significant component degradation was observed. The hot components were coated with a small amount of soot, but no deposits were formed that would lead to plugging or buildup in the turbine housing. The results of the study represent the first step toward development of a biomass BLT. It has been demonstrated that no significant barriers should hamper the use of biomass fuels in the rotor; however, isentropic efficiencies will have to be improved to at least 50% to achieve meaningful overall cycle efficiency.
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Campbell, Levi A., and Satish Kandlikar. "Experimental Study of Heat Transfer, Pressure Drop, and Dryout for Flow Boiling of Water in an Oil Heated Minichannel." In ASME 2004 2nd International Conference on Microchannels and Minichannels. ASMEDC, 2004. http://dx.doi.org/10.1115/icmm2004-2387.
Abstract:
Heat transfer and pressure drop, are experimentally recorded for flow boiling water in a single 706 μm circular copper channel 158.75 mm long. Heat is supplied by heat transfer oil at specified temperatures to a helical channel in the test section. In contrast to other current experimental techniques for flow boiling in small diameter tubes, a uniform temperature boundary condition is employed rather than a constant heat flux condition. The principal results of these experiments are two-phase flow boiling heat transfer rates and an analysis of the time-dependent pressure drop signature during two-phase flow in a minichannel. The range of experiments includes mass fluxes of 43.8–3070 kg/m2s and wall temperatures of 100°C–171.2°C. In all cases the test section water inlet is subcooled to between 72.9°C and 99.6°C. The inlet pressures used are 1.1–230.5 kPa (gage).
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Mukherjee, Bappa, and Kalachand Sain. "Bed-boundary identification from wire-line log data using Walsh transforms technique: A case study of KG basin, India." In SEG Technical Program Expanded Abstracts 2018. Society of Exploration Geophysicists, 2018. http://dx.doi.org/10.1190/segam2018-2998202.1.
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Stephens, Julia E., Mark Celestina, and Christopher Hughes. "Swirl Distortion Using Stream Vanes for Boundary Layer Ingestion Research." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-92073.
Abstract:
Abstract The swirl distortion of a StreamVane™ was investigated in the NASA Glenn Research Center W8 test facility. The StreamVane™ was designed and generated by Virginia Tech based on CFD simulations and included a center body at the aerodynamic interface plane. The swirl pattern generated by the distortion was evaluated using a dense grid of 5-hole Pitot probe measurements captured using a rotating array of probes. Good agreement was found between the design intent and the results at 38.5 kg/s mass flow. The StreamVane™ swirl results were compared to clean facility flow at 5 inlet mass flows and found to be consistent. Additionally, the axial location of the StreamVane™ relative to the measurement plane was investigated to determine the impact on downstream total pressure loss generated by the vanes. The intent of this work was to assess the viability of using a StreamVane™ to generate a Type I or Type II distortion into a Boundary Layer Ingesting propulsor to assess its aerodynamic performance and aeromechanic response.
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Lindstro¨m, Per R. M., and Anders Ulfvarson. "An Experimental Rig for Verification of the Mechanical Properties of Welds Produced at In-Service Welding." In ASME 2003 22nd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2003. http://dx.doi.org/10.1115/omae2003-37105.
Abstract:
The strength of a weld joint is determined by its geometry and its metallurgic structure, which is dependent on the cooling rate, its chemical composition and the original grain size of the base material. During in-service welding of structures affected by a forced flow of fluid on its reversed side the cooling rate depends on the fluid’s boundary layer, the material’s thickness and the heat input of the welding process. Currently, the calculation of the cooling rate during in-service welding is made by means of numerical methods such as the Finite Element Method, FEM. Through the introduction of an apparent thermal conductivity, kPL, it possible to determine the cooling rate for specific welding parameters by means of Rosenthal’s equation. This can be done with a standard pocket calculator. An experimental rig for measurement of the heat transfer during the in-service welding of structures affected by a forced flow of fluid on its reversed side has been designed and built. The physical principles of welding on plates affected by a forced flow of fluid on their reverse side are the same as for welding on the circumference of a pipe containing a forced flow of fluid. In the rig, the required boundary layer is built up in a pipe system by means of a pump. As the flow and the temperature of the fluid can be controlled to simulate the specific heat transfer, it is now possible to verify the values of the apparent thermal conductivity, kPL, that were calculated by means of FEM. A quantitative database will be filled with values of the apparent thermal conductivity, kPL, for various configurations. For the purpose of evaluation and qualification of in-service Welding Procedures Specifications, WPS, the sponsors of the research project use the experimental rig.
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Masithulela, Fulufhelo. "Analysis of Passive Filling With Fibrotic Myocardial Infarction." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50003.
Abstract:
Cardiovascular diseases account for one third of all deaths worldwide, more than 33% of which are related to ischemic heart disease, involving a myocardial infarction (MI). Following myocardial infarction, the injured region and ventricle undergo structural changes which are thought to be caused by elevated stresses and reduction of strains in the infarcted wall. The fibrotic phase is defined as the period when the amount of new collagen and number of fibroblasts rapidly increase in the infarcted tissue. We studied through finite element analysis the mechanics of the infarcted and remodeling rat heart during diastolic filling. Biventricular geometries of healthy and infarcted rat hearts reconstructed from magnetic resonance images were imported in Abaqus©. The passive myocardium was modelled as a nearly incompressible, hyperelastic, transversely isotropic material represented by the strain energy function W = ½C(eQ − 1) with Q = bfE112 + bt(E222 + E332 + E322) + bfs(E122 + E212 + E132 + E312). Material parameters were obtained from literature [1]. As boundary conditions, the circumferential and longitudinal displacements at the base were set to zero. The radial displacements at the base were left free. A linearly increasing pressure from 0 to 3.80 kPa and 0.86 kPa, respectively, was applied to the endocardial surfaces of left and right ventricle. Average radial, circumferential and longitudinal strains during passive filling were −0.331, 0.135, 0.042 and −0.250, −0.078 and 0.046 for the healthy heart and the infarcted heart, respectively. The average radial, circumferential and longitudinal stresses were −1.196 kPa, 3.87 kPa in the healthy heart and 0.424 kPa and −1.90 kPa, 8.74 kPa and 1.69 kPa in the infarcted heart. The strains were considerable lower in the infarcted heart compared to the health heart whereas stresses were higher in the presence of an infarct compared to the healthy case. The results of this study indicate the feasibility of the models developed for a more comprehensive assessment of mechanics of the infarcted ventricle including extension to account for cardiac contraction.
Reports on the topic "KPg boundary":
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Eneroth, Hanna, Hanna Karlsson Potter, and Elin Röös. Environmental impact of coffee, tea and cocoa – data collection for a consumer guide for plant-based foods. Department of Energy and Technology, Swedish University of Agricultural Sciences, 2022. http://dx.doi.org/10.54612/a.2n3m2d2pjl.
Abstract:
In 2020, WWF launched a consumer guide on plant-based products targeting Swedish consumers. The development of the guide is described in a journal paper (Karlsson Potter & Röös, 2021) and the environmental impact of different plant based foods was published in a report (Karlsson Potter, Lundmark, & Röös, 2020). This report was prepared for WWF Sweden to provide scientific background information for complementing the consumer guide with information on coffee, tea and cocoa. This report includes quantitative estimations for several environmental categories (climate, land use, biodiversity and water use) of coffee (per L), tea (per L) and cocoa powder (per kg), building on the previously established methodology for the consumer guide. In addition, scenarios of consumption of coffee, tea and cocoa drink with milk/plant-based drinks and waste at household level, are presented. Tea, coffee and cacao beans have a lot in common. They are tropical perennial crops traditionally grown in the shade among other species, i.e. in agroforestry systems. Today, the production in intensive monocultures has negative impact on biodiversity. Re-introducing agroforestry practices may be part of the solution to improve biodiversity in these landscapes. Climate change will likely, due to changes in temperature, extreme weather events and increases in pests and disease, alter the areas where these crops can be grown in the future. A relatively high ratio of the global land used for coffee, tea and cocoa is certified according to sustainability standards, compared to other crops. Although research on the implications of voluntary standards on different outcomes is inconclusive, the literature supports that certifications have a role in incentivizing more sustainable farming. Coffee, tea and cocoa all contain caffeine and have a high content of bioactive compounds such as antioxidants, and they have all been associated with positive health outcomes. While there is a strong coffee culture in Sweden and coffee contributes substantially to the environmental impact of our diet, tea is a less consumed beverage. Cocoa powder is consumed as a beverage, but substantial amounts of our cocoa consumption is in the form of chocolate. Roasted ground coffee on the Swedish market had a climate impact of 4.0 kg CO2e per kg powder, while the climate impact of instant coffee powder was 11.5 kg CO2e per kg. Per litre, including the energy use for making the coffee, the total climate impact was estimated to 0.25 kg CO2e per L brewed coffee and 0.16 kg CO2e per L for instant coffee. Less green coffee beans are needed to produce the same amount of ready to drink coffee from instant coffee than from brewed coffee. Tea had a climate impact of approximately 6.3 kg CO2 e per kg dry leaves corresponding to an impact of 0.064 CO2e per L ready to drink tea. In the assessment of climate impact per cup, tea had the lowest impact with 0.013 kg CO2e, followed by black instant coffee (0.024 kg CO2e), black coffee (0.038 kg CO2e), and cocoa drink made with milk (0.33 kg CO2e). The climate impact of 1kg cocoa powder on the Swedish market was estimated to 2.8 kg CO2e. Adding milk to coffee or tea increases the climate impact substantially. The literature describes a high proportion of the total climate impact of coffee from the consumer stage due to the electricity used by the coffee machine. However, with the Nordic low-carbon energy mix, the brewing and heating of water and milk contributes to only a minor part of the climate impact of coffee. As in previous research, coffee also had a higher land use, water use and biodiversity impact than tea per L beverage. Another factor of interest at the consumer stage is the waste of prepared coffee. Waste of prepared coffee contributes to climate impact through the additional production costs and electricity for preparation, even though the latter was small in our calculations. The waste of coffee and tea at Summary household level is extensive and measures to reduce the amount of wasted coffee and tea could reduce the environmental impact of Swedish hot drink consumption. For the final evaluation of coffee and tea for the consumer guide, the boundary for the fruit and vegetable group was used. The functional unit for coffee and tea was 1 L prepared beverage without any added milk or sweetener. In the guide, the final evaluation of conventionally grown coffee is that it is ‘yellow’ (‘Consume sometimes’), and for organic produce, ‘light green’ (‘Please consume). The evaluation of conventionally grown tea is that it is ‘light green’, and for organic produce, ‘dark green’ (‘Preferably consume this’). For cocoa, the functional unit is 1 kg of cocoa powder and the boundary was taken from the protein group. The final evaluation of conventionally grown cocoa is that it is ‘orange’ (‘Be careful’), and for organically produced cocoa, ‘light green’.