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| 54. |
- Strömberg, C. A. E., et al.
(författare)
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Palaeoecology of a Middle Miocene lake in China: preliminary interpretations based on phytoliths from the Shanwang Basin
- 2007
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Ingår i: Vertebrata PalAsiatica. ; 45, s. 145-160
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Tidskriftsartikel (refereegranskat)abstract
- The lacustrine Early to Middle Miocene Shanwang Formation contains an exceptionally well preserved biota including insects, plants, and vertebrates that has been subject to intense study. Palaeoecological work on plant macrofossils and palynofloras indicate that the locality represents a forest under a humid, warm-temperate to subtropical climate that remained rather stable during the deposition of the formation. This interpretation is supported by fossil vertebrates such as bats and tapirs discovered in the Shanwang section. However, to date no information has been available on the presence, abundance, and taxonomic composition of grasses at this locality. Here, we report on phytoliths extracted from six samples from the Shanwang Formation, providing new evidence of the vegetation that grew around the lake. The phytolith assemblages contain well-preserved and abundant grass phytoliths, forest indicator phytoliths from dicotyledonous plants, and infrequent palm phytoliths. The grass phytoliths consist of forms produced by C,IC4 PACCAD grasses and pooids, with a minor component of morphotypes thought to derive from closed-habitat grasses. Our preliminary interpretation of these phytolith assemblages is that they reflect a lake-side wooded habitat and abundant helophytic to mesophytic grasses, with drier areas supporting pooid (and PACCAD) grasses. The data support the reconstruction of the Miocene Shanwang region as more humid and equable than presently. The Shanwang phytolith assemblages contrast with Miocene lacustrine phytolith assemblages from Turkey and the Great Plains of North America, which indicate grass communities characterized by diverse C3 pooids and different types of PACCAD grasses. Future research will determine whether this variability reflects large-scale biogeographic differences in grass communities or local, microclimate-related variation.
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| 55. |
- Strömberg, C. A. E., et al.
(författare)
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The spread of grass-dominated habitats in the Eastern Mediterranean during the Cainozoic: phytolith evidence
- 2007
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 250, s. 18-49
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Tidskriftsartikel (refereegranskat)abstract
- The arrival of hipparionine horses in the eastern Mediterranean region around 11 Ma was traditionally thought to mark the simultaneous westward expansion of savanna vegetation across Eurasia. However, recent paleoecological reconstructions based on tooth wear, carbon isotopes, and functional morphology indicate that grasses played a minor role in Late Miocene ecosystems of the eastern Mediterranean, which were more likely dry woodlands or forests. The scarcity of grass macrofossils and pollen in Miocene floras of Europe and Asia Minor has been used to support this interpretation. Based on the combined evidence, it has therefore been suggested that Late Miocene ungulate faunal change in the eastern Mediterranean signals increased aridity and landscape openness, but not necessarily the development of grass-dominated habitats. To shed newlight on the Miocene evolution of eastern Mediterranean ecosystems, we used phytolith assemblages preserved in direct association with faunas as a proxy for paleovegetation structure (grassland vs. forest).We extracted phytoliths and other biogenic silica fromsediment samples fromwell-known Early to Late Miocene (∼20–7Ma) faunal localities in Greece, Turkey, and Iran. In addition, a Middle Eocene sample from Turkey yielded phytoliths and served as a baseline comparison for vegetation inference. Phytolith analysis showed that the Middle Eocene assemblage consists of abundant grass phytoliths (grass silica short cells) interpreted as deriving from bambusoid grasses, as well as diverse forest indicator phytoliths from dicotyledonous angiosperms and palms, pointing to the presence of a woodland or forest with abundant bamboos. In contrast, the Miocene assemblages are dominated by diverse silica short cells typical of pooid open-habitat grasses. Forest indicator phytoliths are also present, but are rare in the Late Miocene (9–7 Ma) assemblages. Our analysis of the Miocene grass community composition is consistent with evidence from stable carbon isotopes from paleosols and ungulate tooth enamel, showing that C4 grasses were rare in the Mediterranean throughout the Miocene. These data indicate that relatively open habitats had become common in Turkey and surrounding areas by at least the Early Miocene (∼20 Ma), N7 million years before hipparionine horses reached Europe and arid conditions ensued, as judged by faunal data.
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| 56. |
- Taghavi, K., et al.
(författare)
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Colposcopy telemedicine: live versus static swede score and accuracy in detecting CIN2+, a cross-sectional pilot study
- 2018
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Ingår i: Bmc Womens Health. - : Springer Science and Business Media LLC. - 1472-6874. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: This cross-sectional pilot study evaluates diagnostic accuracy of live colposcopy versus static image Swede-score evaluation for detecting significant precancerous cervical lesions greater than, or equal to grade 2 severity (CIN2+). Methods: VIA or HrHPV positive women were examined using a mobile colposcope, in a rural clinic in Kolkata, India. Live versus static Swede-score colposcopy assessments were made independently. All assessments were by gynecologists, junior or expert. Static image assessors were blinded to live scoring, patient information and final histopathology result. Primary outcome was the ability to detect CIN2+ lesions verified by directed biopsies. Diagnostic accuracy was calculated for live versus static Swede-score in detecting CIN2+ lesions, as well as for interclass correlation. Results: 495 images from 94 VIA positive women were evaluated in this study. Thirteen women (13.9%) had CIN2+ on biopsy. No significant difference was found in the detection of CIN2+ lesions between live and static assessors (area under curve = 0.69 versus 0.71, p = 0.63). A Swede-score of 4+, had a sensitivity of 76.9% (95% CI 46.2-95.0%) and 84.6% (95% CI 54.6-98.1%), for live-and static-image assessment respectively. The corresponding positive predictive values were found to be 90.9% (95% CI 75.7-98.1%) and 92.6% (95% CI 75.7-99.1%). The interclass correlation was good (kappa statistic = 0.60) for the senior static assessors. Conclusions: Swede-score evaluation of static colposcopy images was found to reliably detect CIN2+ lesions in this study. Larger studies are needed to further develop the colposcopy telemedicine concept which may offer reliable guidance in management where direct specialist input is not available. Trial registration: Ethical approval of the study was obtained by the Chittaranjan National Cancer Institute (CNCI) Human Research Ethics Committee (4.311/27/2014).
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| 57. |
- Taranto, Philip, et al.
(författare)
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Landauer Versus Nernst : What is the True Cost of Cooling a Quantum System
- 2023
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Ingår i: PRX Quantum. - 2691-3399. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Thermodynamics connects our knowledge of the world to our capability to manipulate and thus to control it. This crucial role of control is exemplified by the third law of thermodynamics, Nernst's unattainability principle, which states that infinite resources are required to cool a system to absolute zero temperature. But what are these resources and how should they be utilized And how does this relate to Landauer's principle that famously connects information and thermodynamics We answer these questions by providing a framework for identifying the resources that enable the creation of pure quantum states. We show that perfect cooling is possible with Landauer energy cost given infinite time or control complexity. However, such optimal protocols require complex unitaries generated by an external work source. Restricting to unitaries that can be run solely via a heat engine, we derive a novel Carnot-Landauer limit, along with protocols for its saturation. This generalizes Landauer's principle to a fully thermodynamic setting, leading to a unification with the third law and emphasizes the importance of control in quantum thermodynamics.
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| 58. |
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| 59. |
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| 60. |
- Zhang, C., et al.
(författare)
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Near Earth Vortices Driving of Field Aligned Currents Based on Magnetosphere Multiscale and Swarm Observations
- 2019
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Ingår i: Chinese Journal of Space Science. - : National Space Science Center, Chinese Academy of Sciences. - 0254-6124. ; 39:1, s. 9-17
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Tidskriftsartikel (refereegranskat)abstract
- A long-standing mystery in the study of Field-Aligned Currents (FACs) has been that: how the currents are generated and why they appear to be much stronger at high altitudes than in the ionosphere. Here we present two events of magnetotail FACs observed by the Magnetospheric Multiscale Spacecraft (MMS) on 1st July and 14th July 2016, to show how the Substorm Current Wedges (SCW) were formed. The results show that particles were transferred heading towards the Earth during the expansion phase of substorms. The azimuthal flow formed clockwise (counter-clockwise) vortex-like motion, and then generated downward (upward) FACs on the tailward/poleward side of the distorted field with opposite vorticity on their Earthward/equatorward side. We also analyzed the Region 1 FACs observed by the Earth Explorer Swarm spacecraft on 1st July 2016 and found that they were associated with FACs observed by MMS, although differing by a factor of 10. This difference suggests that either there was the closure of the currents at altitudes above 500 km or the currents were not strictly parallel to B and closed at longitudes away from where they were generated.
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