175 research outputs found

    Magnetoelectric Jones Dichroism in Atoms

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    The authors suggest that atomic experiments measuring the interference between magnetic-dipole and electric-field-induced electric-dipole transition amplitudes provide a valuable system to study magnetoelectric Jones effects.Comment: 3 pages, 2 figure

    EU Nature Restoration Law; EGU Response

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    The EGU Biodiversity Task Force welcomes the ambitious targets outlined in the Nature Restoration Law that was presented by the European Commission on 22 June 2022. To ensure the Nature Restoration Law is successful, the EGU Biodiversity Task Force is recommending seven key points to be added, amended, or strengthened throughout the document

    Palaeoenvironmental History of the Gredos Range (Spanish Central System, Avila) in Visigothic Times: The Impact of the Justinianic Plague (AD 541–543)

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    This paper evaluates the possible impact of the early medieval pandemic known as the “Justinianic plague” as one of the factors that shaped the mountain ecosystems in the Spanish Central System of the Iberian Peninsula. For this purpose, we focus on two high-resolution, radiocarbon-dated natural pollen records from the Gredos Range (Avila). These cores frame the information they offer within the general picture of the socio-political and environmental transformations of Late Antiquity. Along these three centuries, between c. AD 400 and AD 720, the palynological sequence allows us to recognize eight short phases (on a ten-year and even five-year scale) through which the forest formations traversed. This analysis has made it possible to identify olive and chestnut tree arboriculture since the beginning of the studied interval, as well as to characterize the fluctuation in the thinning processes of the high montane pine forests, due to slash-and-burn practices to open pastures, especially from the permanent occupation of the piedmont in Visigothic times (c. AD 450). The sequence also shows a significant decrease in the anthropic signal during a short period (c. AD 540-545) that can be disassociated from the early effects of the Late Antique Little Ice Age (c. AD 450-660) and which is possibly more related to the plague, as evidenced by the subsequent recovery of anthropic pressure on the pine forest and the extension of the olive and chestnut grove in the 6th and 7th centuries AD.El presente trabajo evalúa la posible influencia de la pandemia altomedieval conocida como «plaga de Justiniano» como uno de los factores que contribuyeron a configurar los ecosistemas de montaña enclavados en el Sistema Central de la península ibérica. Para ello, el artículo se centra en dos registros polínicos naturales de alta resolución y bien datados mediante radiocarbono, obtenidos en la Sierra de Gredos (Ávila), y enmarca la información que ofrecen en el cuadro general de las dinámicas sociopolíticas y ambientales de la Antigüedad Tardía. En el intervalo de tres siglos, entre c. 400 y 720 A. D., la secuencia palinológica permite reconocer ocho fases breves (de escala decenal e incluso quinquenal) que marcaron las transformaciones del paisaje. Este análisis ha posibilitado identificar la implantación de la arboricultura de olivo y castaño desde el inicio del intervalo estudiado, así como caracterizar la fluctuación en los procesos de clareo de los pinares altimontanos, por la incidencia de talas y rozas con fuego para abrir pastizales, especialmente desde la ocupación permanente del piedemonte en época visigoda (c. 450 A. D.). La secuencia analizada muestra un significativo aminoramiento de la señal antrópica durante un breve intervalo (c. 540-545 A. D.) que cabe desvincular de los efectos tempranos de la Pequeña Edad de Hielo tardoantigua (c. 450-660 A. D.) y resulta más plausible relacionar con la plaga, como avala la subsiguiente recuperación de la presión antrópica sobre el pinar y la extensión del olivar y el castañar en los siglos VI y VII A. D.- Introducción - Zona de estudio - Consideraciones metodológicas - Historia de la vegetación e impacto humano (400-720 A.D.) - Conclusiones, variabilidad climática y efectos de la pandemia (541-543 A.D.

    La peste negra bajomedieval (1348-1351 AD) en el valle del Tiétar (sierra de Gredos, Ávila): aspectos económicos y paleoambientales

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    En el presente trabajo se evalúan los efectos de la peste negra bajomedieval (1348–1351 AD) sobre los bosques y las actividades agroforestales de un valle intramontano de la Meseta sur española, a partir de análisis polínicos de alta resolución. Para comprender mejor los efectos de aquella pandemia se analiza la secuencia paleoambiental de cinco turberas, a lo largo de un amplio recorrido cronológico entre los siglos XII y XIV. Este análisis demuestra que la peste provocó una desaceleración de las actividades agropecuarias –agricultura, arboricultura, ganadería– y la consiguiente recuperación de las masas forestales, salvo en las zonas de montaña donde un menor control de los pasos ganaderos incidió en cierta degradación del bosque.1 Introducción 2 Área de estudio y metodología 2.1 El valle del Tiétar en la provincia de Ávila 2.2 Registros polínicos fósiles 3 Resultados y discusión 3.1 Antes de la pandemia (1200–1348 AD) 3.2 La epidemia de peste negra en la sierra de Gredos (1348–1351 AD) 3.3 Recuperación tras la pandemia (1351–1400 AD) 4 Conclusione

    Palaeoecological data indicates land-use changes across Europe linked to spatial heterogeneity in mortality during the Black Death pandemic

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    The Black Death (1347-1352 CE) is the most renowned pandemic in human history, believed by many to have killed half of Europe's population. However, despite advances in ancient DNA research that conclusively identified the pandemic's causative agent (bacterium Yersinia pestis), our knowledge of the Black Death remains limited, based primarily on qualitative remarks in medieval written sources available for some areas of Western Europe. Here, we remedy this situation by applying a pioneering new approach, 'big data palaeoecology', which, starting from palynological data, evaluates the scale of the Black Death's mortality on a regional scale across Europe. We collected pollen data on landscape change from 261 radiocarbon-dated coring sites (lakes and wetlands) located across 19 modern-day European countries. We used two independent methods of analysis to evaluate whether the changes we see in the landscape at the time of the Black Death agree with the hypothesis that a large portion of the population, upwards of half, died within a few years in the 21 historical regions we studied. While we can confirm that the Black Death had a devastating impact in some regions, we found that it had negligible or no impact in others. These inter-regional differences in the Black Death's mortality across Europe demonstrate the significance of cultural, ecological, economic, societal and climatic factors that mediated the dissemination and impact of the disease. The complex interplay of these factors, along with the historical ecology of plague, should be a focus of future research on historical pandemics.The authors acknowledge the following funding sources: Max Planck Independent Research Group, Palaeo-Science and History Group (A.I., A.M. and C.V.); Estonian Research Council #PRG323, PUT1173 (A.Pos., T.R., N.S. and S.V.); European Research Council #FP7 263735 (A.Bro. and A.Plu.), #MSC 655659 (A.E.); Georgetown Environmental Initiative (T.N.); Latvian Council of Science #LZP-2020/2-0060 (N.S. and N.J.); LLNL-JRNL-820941 (I.T.); NSF award #GSS-1228126 (S.M.); Polish-Swiss Research Programme #013/2010 CLIMPEAT (M.Lam.), #086/2010 CLIMPOL (A.W.); Polish Ministry of Science and Higher Education #N N306 275635 (M.K.); Polish National Science Centre #2019/03/X/ST10/00849 (M.Lam.), #2015/17/B/ST10/01656 (M.Lam.), #2015/17/B/ST10/03430 (M.Sło.), #2018/31/B/ST10/02498 (M.Sło.), #N N304 319636 (A.W.); SCIEX #12.286 (K.Mar.); Spanish Ministry of Economy and Competitiveness #REDISCO-HAR2017-88035-P (J.A.L.S.); Spanish Ministry of Education, Culture and Sports #FPU16/00676 (R.L.L.); Swedish Research Council #421-2010-1570 (P.L.), #2018-01272 (F.C.L. and A.S.); Volkswagen Foundation Freigeist Fellowship Dantean Anomaly (M.B.), Spanish Ministry of Science and Innovation #RTI2018-101714-B-I00 (F.A.S. and D.A.S.), OP RDE, MEYS project #CZ.02.1.01/0.0/0.0/16_019/0000728 (P.P.

    A comparison of ZnMgSSe and MgS wide bandgap semiconductors used as barriers: Growth, structure and luminescence properties

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    a b s t r a c t The wide bandgap alloy Zn 0.2 Mg 0.8 S 0.64 Se 0.36 has recently been grown by molecular beam epitaxy (MBE) and been shown to be oxidation and acid resistant. This makes it attractive either as a replacement or adjunct to MgS in II-VI multilayers. In this paper we compare the structural and optical properties of MBE grown multilayer structures containing Zn 0.2 Mg 0.8 S 0.64 Se 0.36 to those grown with the quaternary alloy replaced by MgS. Cross-sectional high-resolution transmission electron microscopy (HRTEM) and X-ray interference spectra of ZnSe/Zn 0. This has allowed us to demonstrate the use of the quaternary alloy, which resists oxidation in place of MgS in multilayer structures

    Realising consilience: How better communication between archaeologists, historians and natural scientists can transform the study of past climate change in the Mediterranean

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    This paper reviews the methodological and practical issues relevant to the ways in which natural scientists, historians and archaeologists may collaborate in the study of past climatic changes in the Mediterranean basin. We begin by discussing the methodologies of these three disciplines in the context of the consilience debate, that is, attempts to unify different research methodologies that address similar problems. We demonstrate that there are a number of similarities in the fundamental methodology between history, archaeology, and the natural sciences that deal with the past (“palaeoenvironmental sciences”), due to their common interest in studying societal and environmental phenomena that no longer exist. The three research traditions, for instance, employ specific narrative structures as a means of communicating research results. We thus present and compare the narratives characteristic of each discipline; in order to engage in fruitful interdisciplinary exchange, we must first understand how each deals with the societal impacts of climatic change. In the second part of the paper, we focus our discussion on the four major practical issues that hinder communication between the three disciplines. These include terminological misunderstandings, problems relevant to project design, divergences in publication cultures, and differing views on the impact of research. Among other recommendations, we suggest that scholars from the three disciplines should aim to create a joint publication culture, which should also appeal to a wider public, both inside and outside of academia.This paper emerged as a result of a workshop at Costa Navarino and the Navarino Environmental Observatory (NEO), Greece in April 2014, which addressed Mediterranean Holocene climate and human societies. The workshop was co-sponsored by IGBP/PAGES, NEO, the MISTRALS/PaleoMex program, the Labex OT-Med, the Bolin Centre for Climate Research at Stockholm University, and the Institute of Oceanography at the Hellenic Centre for Marine Research. We also acknowledge funding from the National Science Centre, Poland, within the scheme of the Centre's postdoctoral fellowships (DEC-2012/04/S/HS3/00226 (A.I)); the Swedish Research Council (grant numbers 421-2014-1181 (E.W.) and 621-2012-4344 (K.H.)); CSIC-Ramón y Cajal post-doctoral program RYC-2013-14073 and Clare Hall College, Cambridge, Shackleton Fellowship (B.M.); the EU/FP7 Project ‘Sea for Society’ (Science and Society - 2011-1, 289066)

    Assessing the impact of shipping emissions on air pollution in the Canadian Arctic and northern regions: current and future modelled scenarios

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    A first regional assessment of the impact of shipping emissions on air pollution in the Canadian Arctic and northern regions was conducted in this study. Model simulations were carried out on a limited-area domain (at 15&thinsp;km horizontal resolution) centred over the Canadian Arctic, using the Environment and Climate Change Canada's on-line air quality forecast model, GEM-MACH (Global Environmental Multi-scale – Modelling Air quality and CHemistry), to investigate the contribution from the marine shipping emissions over the Canadian Arctic waters (at both present and projected future levels) to ambient concentrations of criteria pollutants (O3, PM2.5, NO2, and SO2), atmospheric deposition of sulfur (S) and nitrogen (N), and atmospheric loading and deposition of black carbon (BC) in the Arctic. Several model upgrades were introduced for this study, including the treatment of sea ice in the dry deposition parameterization, chemical lateral boundary conditions, and the inclusion of North American wildfire emissions. The model is shown to have similar skills in predicting ambient O3 and PM2.5 concentrations in the Canadian Arctic and northern regions, as the current operational air quality forecast models in North America and Europe. In particular, the model is able to simulate the observed O3 and PM components well at the Canadian high Arctic site, Alert. The model assessment shows that, at the current (2010) level, Arctic shipping emissions contribute to less than 1&thinsp;% of ambient O3 concentration over the eastern Canadian Arctic and between 1 and 5&thinsp;% of ambient PM2.5 concentration over the shipping channels. Arctic shipping emissions make a much greater contributions to the ambient NO2 and SO2 concentrations, at 10&thinsp;%–50&thinsp;% and 20&thinsp;%–100&thinsp;%, respectively. At the projected 2030 business-as-usual (BAU) level, the impact of Arctic shipping emissions is predicted to increase to up to 5&thinsp;% in ambient O3 concentration over a broad region of the Canadian Arctic and to 5&thinsp;%–20&thinsp;% in ambient PM2.5 concentration over the shipping channels. In contrast, if emission controls such as the ones implemented in the current North American Emission Control Area (NA ECA) are to be put in place over the Canadian Arctic waters, the impact of shipping to ambient criteria pollutants would be significantly reduced. For example, with NA-ECA-like controls, the shipping contributions to the population-weighted concentrations of SO2 and PM2.5 would be brought down to below the current level. The contribution of Canadian Arctic shipping to the atmospheric deposition of sulfur and nitrogen is small at the current level, &lt;&thinsp;5&thinsp;%, but is expected to increase to up to 20&thinsp;% for sulfur and 50&thinsp;% for nitrogen under the 2030 BAU scenario. At the current level, Canadian Arctic shipping also makes only small contributions to BC column loading and BC deposition, with &lt;&thinsp;0.1&thinsp;% on average and up to 2&thinsp;% locally over the eastern Canadian Arctic for the former, and between 0.1&thinsp;% and 0.5&thinsp;% over the shipping channels for the latter. The impacts are again predicted to increase at the projected 2030 BAU level, particularly over the Baffin Island and Baffin Bay area in response to the projected increase in ship traffic there, e.g., up to 15&thinsp;% on BC column loading and locally exceeding 30&thinsp;% on BC deposition. Overall, the study indicates that shipping-induced changes in atmospheric composition and deposition are at regional to local scales (particularly in the Arctic). Climate feedbacks are thus likely to act at these scales, so climate impact assessments will require modelling undertaken at much finer resolutions than those used in the existing radiative forcing and climate impact assessments.</p
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