| 1. |
- Watts, Anna L., et al.
(författare)
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Dense matter with eXTP
- 2019
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Ingår i: Science China Physics, Mechanics & Astronomy. - : Science Press. - 1674-7348 .- 1869-1927. ; 62:2
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Forskningsöversikt (refereegranskat)abstract
- In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is expected to be launched in the mid 2020s.
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| 2. |
- Büntgen, Ulf, et al.
(författare)
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The influence of decision-making in tree ring-based climate reconstructions
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Tree-ring chronologies underpin the majority of annually-resolved reconstructions of Common Era climate. However, they are derived using different datasets and techniques, the ramifications of which have hitherto been little explored. Here, we report the results of a double-blind experiment that yielded 15 Northern Hemisphere summer temperature reconstructions from a common network of regional tree-ring width datasets. Taken together as an ensemble, the Common Era reconstruction mean correlates with instrumental temperatures from 1794–2016 CE at 0.79 (p < 0.001), reveals summer cooling in the years following large volcanic eruptions, and exhibits strong warming since the 1980s. Differing in their mean, variance, amplitude, sensitivity, and persistence, the ensemble members demonstrate the influence of subjectivity in the reconstruction process. We therefore recommend the routine use of ensemble reconstruction approaches to provide a moreconsensual picture of past climate variability.
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| 3. |
- Hernández, Armand, et al.
(författare)
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Modes of climate variability : Synthesis and review of proxy-based reconstructions through the Holocene
- 2020
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Ingår i: Earth-Science Reviews. - : Elsevier BV. - 0012-8252. ; 209
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Forskningsöversikt (refereegranskat)abstract
- Modes of climate variability affect global and regional climates on different spatio-temporal scales, and they have important impacts on human activities and ecosystems. As these modes are a useful tool for simplifying the understanding of the climate system, it is crucial that we gain improved knowledge of their long-term past evolution and interactions over time to contextualise their present and future behaviour. We review the literature focused on proxy-based reconstructions of modes of climate variability during the Holocene (i.e., the last 11.7 thousand years) with a special emphasis on i) proxy-based reconstruction methods; ii) available proxy-based reconstructions of the main modes of variability, i.e., El Niño Southern Oscillation, Pacific Decadal Variability, Atlantic Multidecadal Variability, the North Atlantic Oscillation, the Southern Annular Mode and the Indian Ocean Dipole; iii) major interactions between these modes; and iv) external forcing mechanisms related to the evolution of these modes. This review shows that modes of variability can be reconstructed using proxy-based records from a wide range of natural archives, but these reconstructions are scarce beyond the last millennium, partly due to the lack of robust chronologies with reduced dating uncertainties, technical issues related to proxy calibration, and difficulty elucidating their stationary impact (or not) on regional climates over time. While for each mode the available reconstructions tend to agree at mutidecadal timescales, they show notable disagreement on shorter timescales beyond the instrumental period. The reviewed evidence suggests that the intrinsic variability of modes can be modulated by external forcing, such as orbital, solar, volcanic, and anthropogenic forcing. The review also highlights some modes experience higher variability over the instrumental period, which is partly ascribed to anthropogenic forcing. These features stress the paramount importance of further studying their past variations using long climate-proxy records for the progress of climate science.
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| 4. |
- Xu, Guobao, et al.
(författare)
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Century-scale temperature variability and onset of industrial-era warming in the Eastern Tibetan Plateau
- 2019
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Ingår i: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 53:7-8, s. 4569-4590
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Tidskriftsartikel (refereegranskat)abstract
- To improve our understanding of climate variability in the Tibetan Plateau (TP) and its sensitivity to external forcings, recent temperature changes need to be placed in a long-term historical context. Here, we present two tree-ring based temperature reconstructions: a 1003-year (1000-2002 CE) annual temperature reconstruction for the northeastern TP (NETP) based on seven series and a 522-year (1489-2010 CE) summer (June-July-August) temperature reconstruction for the southeastern TP (SETP) based on 11 series. Our reconstructions show six centuries of generally warm NETP temperatures (1000-1586 CE), followed by a transition to cooler temperatures (1587-1887 CE for NETP and 1588-1930 CE for SETP). The transition from the Medieval Climate Anomaly to the Little Ice Age thus happened in the 1580s in NETP and SETP, which is about 150 years later than in larger-scale (e.g. Asia and the Northern Hemisphere) temperature reconstructions. We found that TP temperature variability, especially in SETP, was influenced by the Atlantic multi-decadal oscillation and that the twentieth century was the warmest on record in NETP and SETP. Our reconstructions and climate model simulations both show industrial-era warming trends, the onset of which happened earlier in NETP (1812 CE) compared to SETP (1887 CE) and other temperature reconstructions for Western China, East Asia, Asia, and the Northern Hemisphere. The early NETP onset of industrial-era warming can likely be explained by NETP's faster warming rate and by local feedback factors (i.e., ice-snow cover-albedo). Comparisons between climate model simulations and our reconstructions reveal that cooler TP temperatures from 1600 to 1800 CE might be related to land-use and land-cover change.
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| 5. |
- Xu, Guobao, et al.
(författare)
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Tree ring O-18's indication of a shift to a wetter climate since the 1880s in the western Tianshan Mountains of northwestern China
- 2015
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Ingår i: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 120:13, s. 6409-6425
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Tidskriftsartikel (refereegranskat)abstract
- Central Asian droughts have drastically and significantly affected agriculture and water resource management in these arid and semiarid areas. Based on tree ring O-18 from native, dominant Schrenk spruce (Picea schrenkiana Fisch. et Mey.), we developed a 300year (1710-2010) standard precipitation-evaporation index (SPEI) reconstruction from January to August for China's western Tianshan Mountains. The regression model explained 37.6% of the variation in the SPEI reconstruction during the calibration period from 1950 to 2010. Comparison with previous drought reconstructions confirmed the robustness of our reconstruction. The 20th century has been a relatively wet period during the past 300years. The SPEI showed quasi 2, 5, and 10year cycles. Several pluvials and droughts with covariability over large areas were revealed clearly in the reconstruction. The two longest pluvials (lasting for 12years), separated by 50years, appeared in the 1900s and the 1960s. The most severe drought occurred from 1739 to 1761 and from 1886 to 1911 was the wettest period since 1710. Compared to previous investigations of hydroclimatic changes in the western Tianshan Mountains, our reconstruction revealed more low-frequency variability and indicated that climate in the western Tianshan Mountains shifted from dry to wet in 1886. This regime shift was generally consistent with other moisture reconstructions for the northeastern Tibetan Plateau and northern Pakistan and may have resulted from a strengthened westerly circulation. The opposite hydrological trends in the western Tianshan Mountains and southeastern Tibetan Plateau reveal a substantial influence of strengthened westerlies and weakening of the Indian summer monsoon.
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| 6. |
- Zafar, Muhammad Nadeem, et al.
(författare)
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An efficient and versatile membraneless bioanode for biofuel cells based on Corynascus thermophilus cellobiose dehydrogenase
- 2019
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 295, s. 316-324
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the effect of carbon nanotubes (CNTs) either single walled (SWCNT) or multi walled (MWCNT) on sugar oxidation by Corynascus thermophilus cellobiose dehydrogenase (CtCDH) is investigated. The current observed for the direct electron transfer (DET) communication between the enzyme and the electrode is compared to that of the mediated electron transfer (MET) obtained from CtCDH/CNT/Os-polymer modified electrodes. The CNTs provide a high surface area for the immobilization of CtCDH and the Os-polymer and increases the amount of both on the electrode surface. The amperometric current density measured for 50 mM glucose at pH 7.4 and an applied potential of 290 mV vs. SHE in DET mode is 6.90 μA cm−2, which is further improved to about 8.73 μA cm−2 when a cross-linker is applied, whereas a 14-folds increase to 97.6 μA cm−2 is observed for MET when CtCDH is immobilized in the Os-polymer and cross-linked. The current densities extracted from CVs at 150 mV vs. SHE using 20 mM glucose for CtCDH immobilized with the Os-polymer, MWCNT/Os-polymer and SWCNT/Os-polymer are 139.7, 180.3 and 328.2 μA cm−2, respectively so a remarkable increase is observed when using SWCNT for electrode modification. The bioanode also exhibits a good stability and it retains more than 50% of its activity in multicycle CV scan after five days. Thus the bioanode based on SWCNT/CtCDH/Os-polymer/cross-linker could be a promising electrode for application as anode in enzymatic biofuel cells.
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