Polarity reversals of remanent magnetization in a sedimentary core from Northwind Ridge, western Arctic Ocean

We studied the remanent magnetization of a sedimentary core PC2 (6.48m length) drilled during the MR99-K05 cruise of JAMSTEC in the western Arctic Ocean. Discrete specimens and u-channel samples were used in the study. In the discrete specimens, the change of remanent magnetization with depth show many clear polarity reversals in both inclination and declination. Furthermore, most reversals in discrete specimens correlated well with those in the u-channel samples. Core PC2 is characterized by distinct alternations of dark gray and brownish layers. Through comparison of lithostratigraphic cycles with glacial-interglacial cycles (referring to R.L. Phillips and A. Grantz, Geol. Soc. Am. Bull., 109, 1101, 1997), sedimentary cycles of core PC2 are correlated to marine isotope stages up to MIS-8. This indicates that polarity reversals of remanent magnetization in core PC2 are geomagnetic excursions in the Brunhes epoch. Comparison with the previously known geomagnetic excursions shows that the polarity reversals are clear and have long duration in core PC2. This feature may be related to characteristic geomagnetism around the western Arctic Ocean

Universal Money as the Unity of Hoard of Value and Means of Payment

吉信肅教授古稀記念特

Genetic diversity in two sibling species of the Anopheles punctulatus group of mosquitoes on Guadalcanal in the Solomon Islands

<p>Abstract</p> <p>Background</p> <p>The mosquito <it>Anopheles irenicus</it>, a member of the <it>Anopheles punctulatus </it>group, is geographically restricted to Guadalcanal in the Solomon Islands. It shows remarkable morphological similarities to one of its sibling species, <it>An. farauti sensu stricto </it>(<it>An. farauti s.s</it>.), but is dissimilar in host and habitat preferences. To infer the genetic variations between these two species, we have analyzed mitochondrial <it>cytochrome oxidase subunit II </it>(<it>COII</it>) and nuclear ribosomal <it>internal transcribed spacer 2 </it>(<it>ITS2</it>) sequences from Guadalcanal and from one of its nearest neighbours, Malaita, in the Solomon Islands.</p> <p>Results</p> <p><it>An. farauti s.s</it>. was collected mostly from brackish water and by the human bait method on both islands, whereas <it>An. irenicus </it>was only collected from fresh water bodies on Guadalcanal Island. <it>An. irenicus </it>is distributed evenly with <it>An. farauti s.s</it>. (Φ_SC= 0.033, 0.38%) and its range overlaps in three of the seven sampling sites. However, there is a significant population genetic structure between the species (Φ_CT= 0.863, <it>P </it>< 0.01; Φ_ST= 0.865, <it>P </it>< 0.01 and <it>F</it>_ST= 0.878, <it>P </it>< 0.01). Phylogenetic analyses suggest that <it>An. irenicus </it>is a monophyletic species, not a hybrid, and is closely related to the <it>An. farauti s.s</it>. on Guadalcanal. The time estimator suggests that <it>An. irenicus </it>diverged from the ancestral <it>An. farauti s.s</it>. on Guadalcanal within 29,000 years before present (BP). <it>An. farauti s.s</it>. expanded much earlier on Malaita (<it>t</it>_exp= 24,600 BP) than the populations on Guadalcanal (<it>t</it>_exp= 16,800 BP for <it>An. farauti s.s</it>. and 14,000 BP for <it>An. irenicus</it>).</p> <p>Conclusion</p> <p>These findings suggest that <it>An. irenicus </it>and <it>An. farauti s.s</it>. are monophyletic sister species living in sympatry, and their populations on Guadalcanal have recently expanded. Consequently, the findings further suggest that <it>An. irenicus </it>diverged from the ancestral <it>An. farauti s.s</it>. on Guadalcanal.</p

Sensory analysis and acceptance of feijoa fruit

The southern region of Brazil is home of a myriad of native species which have high organoleptic potential, and among those species the feijoa fruit (Feijoa sellowiana) stands out. This species has an incipient production chain; however, the promotion of the species to the consumers can increase the fruit’s consumption, stimulate its production, in addition to its conservation. This study aims to perform sensory analysis and verify the preference for fruits of two cultivars and a selection of F. sellowiana. Fifty-seven tasters evaluated the fruits for sensory characteristics, taste and appearance. The evaluations included a questionnaire to characterize the taster’s profile. The tasters’ perception of the three samples did not differ in terms of sweetness, acidity, juiciness, pulp yield and overall impression. In general, the sensorial analysis showed that feijoa is a fruit with notorious acceptance by consumers. This result demonstrates the potential for promotion and use of the species, in order to make compatible the promotion of its cultivation and conservation

Multiple episodes of ice loss from the Wilkes Subglacial Basin during the Last Interglacial

The Last Interglacial (LIG: 130,000–115,000 years ago) was a period of warmer global mean temperatures and higher and more variable sea levels than the Holocene (11,700–0 years ago). Therefore, a better understanding of Antarctic ice-sheet dynamics during this interval would provide valuable insights for projecting sea-level change in future warming scenarios. Here we present a high-resolution record constraining ice-sheet changes in the Wilkes Subglacial Basin (WSB) of East Antarctica during the LIG, based on analysis of sediment provenance and an ice melt proxy in a marine sediment core retrieved from the Wilkes Land margin. Our sedimentary records, together with existing ice-core records, reveal dynamic fluctuations of the ice sheet in the WSB, with thinning, melting, and potentially retreat leading to ice loss during both early and late stages of the LIG. We suggest that such changes along the East Antarctic Ice Sheet margin may have contributed to fluctuating global sea levels during the LIG

Multiple episodes of ice loss from the Wilkes Subglacial Basin during the Last Interglacial

The Last Interglacial (LIG: 130,000-115,000 years ago) was a period of warmer global mean temperatures and higher and more variable sea levels than the Holocene (11,700-0 years ago). Therefore, a better understanding of Antarctic ice-sheet dynamics during this interval would provide valuable insights for projecting sea-level change in future warming scenarios. Here we present a high-resolution record constraining ice-sheet changes in the Wilkes Subglacial Basin (WSB) of East Antarctica during the LIG, based on analysis of sediment provenance and an ice melt proxy in a marine sediment core retrieved from the Wilkes Land margin. Our sedimentary records, together with existing ice-core records, reveal dynamic fluctuations of the ice sheet in the WSB, with thinning, melting, and potentially retreat leading to ice loss during both early and late stages of the LIG. We suggest that such changes along the East Antarctic Ice Sheet margin may have contributed to fluctuating global sea levels during the LIG

Salivary Biomarkers May Be Useful to Assess Stress State in Patients with Lung Cancer Undergoing Chemotherapy

ABSTRAC

Radiolarian assemblages related to the ocean–ice interaction around the East Antarctic coast

The Southern Ocean plays a central role in Earth's climate, ecology, and biogeochemical cycles. Therefore, understanding long-term changes in Southern Ocean water masses in the geologic past is essential for assessing the role of the Southern Ocean in the climate system. Radiolarian fossils are a useful tool to reconstruct the water masses of the Southern Ocean. However, the radiolarian assemblages in the high latitudes of the Southern Ocean (south of the polar front (PF)) are still poorly understood. In this paper, we report the radiolarian assemblages in surface marine sediment and plankton tow samples collected from the high latitudes south of the PF. In the surface sediments, four factors (named F1–F4) of the radiolarian assemblages were identified using Q-mode factor analysis, which are related to different water masses and hydrological conditions. F1 is related to the surface waters south of the southern boundary (SB) of the Antarctic Circumpolar Current (ACC), which are cooled by melting sea ice and ice sheets. F2 is associated with water masses north of the SB. A comparison with the vertical distribution of the radiolarian assemblages in plankton tow samples indicates that characteristic species are associated with the Circumpolar Deep Water (CDW) and surface waters north of the SB. F3 is associated with modified Circumpolar Deep Water (mCDW). The radiolarian assemblage of F4 does not seem specifically related to any of the water mass here analyzed. However, the species in this assemblage are typically dwells within ice shelf and/or sea ice edge environments. Radiolarian assemblages here identified and associated with water masses, and ice edge environments are useful to reconstruct the environment south of the PF in the geologic past.</p

Paleoclimatic and paleoceanographic records through Marine Isotope Stage 19 at the Chiba composite section, central Japan: A key reference for the EarlyeMiddle Pleistocene Subseries boundary

Marine Isotope Stage (MIS) 19 is an important analogue for the present interglacial because of its similar orbital configuration, especially the phasing of the obliquity maximum to precession minimum. However, sedimentary records suitable for capturing both terrestrial and marine environmental changes are limited, and thus the climatic forcing mechanisms for MIS 19 are still largely unknown. The Chiba composite section, east-central Japanese archipelago, is a continuous and expanded marine sedimentary succession well suited to capture terrestrial and marine environmental changes through MIS 19. In this study, a detailed oxygen isotope chronology is established from late MIS 20 to early MIS 18, supported by a U-Pb zircon age and the presence of the Matuyama–Brunhes boundary. New pollen, marine microfossil, and planktonic foraminiferal δ18O and Mg/Ca paleotemperature records reveal the complex interplay of climatic influences. Our pollen data suggest that the duration of full interglacial conditions during MIS 19 extends from 785.0 to 775.1 ka (9.9 kyr), which offers an important natural baseline in predicting the duration of the present interglacial. A Younger Dryas-type cooling event is present during Termination IX, suggesting that such events are linked to this orbital configuration. Millennial- to multi-millennial-scale variations in our δ18O and Mg/Ca records imply that the Subarctic Front fluctuated in the northwestern Pacific Ocean during late MIS 19, probably in response to East Asian winter monsoon variability. The climatic setting at this time appears to be related to less severe summer insolation minima at 65˚N and/or high winter insolation at 50˚N. Our records do not support a recently hypothesized direct coupling between variations in the geomagnetic field intensity and global/regional climate change. Our highly resolved paleoclimatic and paleoceanographic records, coupled with a well-defined Matuyama–Brunhes boundary (772.9 ka; duration 1.9 kyr), establish the Chiba composite section as an exceptional climatic and chronological reference section for the Early–Middle Pleistocene boundary.ArticleQuaternary Science Reviews 191: 406-430(2018)journal articl