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Author |
Amandine Kaiser, Davide Faranda, Sebastian Krumscheid, Danijel Belušić, Nikki Vercauteren |
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Title  |
Detecting Regime Transitions of the Nocturnal and Polar Near-Surface Temperature Inversion |
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Year |
2020 |
Publication |
Journal of the atmospheric sciences |
Abbreviated Journal |
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Volume |
77 |
Issue |
8 |
Pages |
2921-2940 |
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Abstract |
Abstract Many natural systems undergo critical transitions, i.e., sudden shifts from one dynamical regime to another. In the climate system, the atmospheric boundary layer can experience sudden transitions between fully turbulent states and quiescent, quasi-laminar states. Such rapid transitions are observed in polar regions or at night when the atmospheric boundary layer is stably stratified, and they have important consequences in the strength of mixing with the higher levels of the atmosphere. To analyze the stable boundary layer, many approaches rely on the identification of regimes that are commonly denoted as weakly and very stable regimes. Detecting transitions between the regimes is crucial for modeling purposes. In this work a combination of methods from dynamical systems and statistical modeling is applied to study these regime transitions and to develop an early warning signal that can be applied to nonstationary field data. The presented metric aims to detect nearing transitions by statistically quantifying the deviation from the dynamics expected when the system is close to a stable equilibrium. An idealized stochastic model of near-surface inversions is used to evaluate the potential of the metric as an indicator of regime transitions. In this stochastic system, small-scale perturbations can be amplified due to the nonlinearity, resulting in transitions between two possible equilibria of the temperature inversion. The simulations show such noise-induced regime transitions, successfully identified by the indicator. The indicator is further applied to time series data from nocturnal and polar meteorological measurements. |
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1013 |
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0022-4928, 1520-0469 |
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yes |
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Serial |
8151 |
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Author |
J. Jumelet, A. R. Klekociuk, S. P. Alexander, S. Bekki, A. Hauchecorne, J. P. Vernier, M. Fromm, P. Keckhut |
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Title |
Detection of Aerosols in Antarctica From Long-Range Transport of the 2009 Australian Wildfires |
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Journal |
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Year |
2020 |
Publication |
Journal of Geophysical Research: Atmospheres |
Abbreviated Journal |
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Volume |
125 |
Issue |
23 |
Pages |
e2020JD032542 |
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Keywords |
aerosols Antarctica bushfires lidar |
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Abstract |
We analyze the long-range transport to high latitudes of a smoke particle filament originating from the extratropics plume after the Australian wildfires colloquially known as “Black Saturday” on 7 February and report the first Antarctic stratospheric lidar characterization of such aerosols. Using a high-resolution transport/microphysical model, we show that the monitoring cloud/aerosol lidar instrument operating at the French Antarctic station Dumont d'Urville (DDU, 66°S to 140°E) recorded a signature of those aerosols. The 532 nm scattering ratio of this filament is comparable to typical moderate stratospheric volcanic plume, with values between 1.4 and 1.6 on the first and third days of March above DDU station at around the 14 and 16 km altitude, respectively. A dedicated model is described and its ability to track down fine optical signatures is validated against Antarctic lidar elastic aerosol and DIAL ozone measurements. Using 1 month of tropical Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data to support a relatively simple microphysical scheme, we report modeled aerosol presence above DDU station after advection of the aerosol size distribution. In situ measurements also report associated positive ozone anomaly. This case study provides evidence that biomass burning events injecting significant amounts of material up to stratospheric altitudes can be transported toward high latitudes. We highlight a potential imprint of smoke particles on the Antarctic atmosphere over larger time scales. Any underestimation of the global impact of such deep particle transport will lead to uncertainties in modeling the associated chemical or radiative effects, especially in polar regions, where specific microphysical and chemical processes take place. |
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209 |
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2169-8996 |
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yes |
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8015 |
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Author |
Guillot T. |
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Title |
Discovering Exoplanets from Antarctica with ASTEP |
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Conference - International - Communication |
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Year |
2020 |
Publication |
On the way to Antarctica seminar, 29 october 2020 |
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Programme |
1066 |
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Bachelor's thesis |
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yes |
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Serial |
7829 |
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Author |
S. Fabri-Ruiz, N. Navarro, R. Laffont, B. Danis, T. Saucède |
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Title |
Diversity of Antarctic Echinoids and Ecoregions of the Southern Ocean |
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Journal |
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Year |
2020 |
Publication |
Biology bulletin |
Abbreviated Journal |
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Volume |
47 |
Issue |
6 |
Pages |
683-698 |
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Abstract |
Significant environmental changes have already been documented in the Southern Ocean (e.g. sea water temperature increase and salinity drop) but its marine life is still incompletely known given the heterogeneous nature of biogeographic data. However, to establish sustainable conservation areas, understanding species and communities distribution patterns is critical. For this purpose, the ecoregionalization approach can prove useful by identifying spatially explicit and well-delimited regions of common species composition and environmental settings. Such regions are expected to have similar biotic responses to environmental changes and can be used to define priorities for the designation of Marine Protected Areas. In the present work, a benthic ecoregionalization of the Southern Ocean is proposed based on echinoids distribution data and abiotic environmental parameters. Echinoids are widely distributed in the Southern Ocean, they are taxonomically and ecologically well diversified and documented. Given the heterogeneity of the sampling effort, predictive spatial models were produced to fill the gaps in between species distribution data. A first procedure was developed using Gaussian Mixture Models (GMM) to combine individual species models into ecoregions. A second, integrative procedure was implemented using the Generalized Dissimilarity Models (GDM) to model and assemble species distributions. Both procedures were compared to propose benthic ecoregions at the scale of the entire Southern Ocean. |
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1044 |
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ISSN |
1608-3059 |
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yes |
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Call Number |
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Serial |
6698 |
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Author |
Morgan Godard, Claude Manté, Christophe Guinet, Baptiste Picard, David Nerini |
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Title |
Diving Behavior of Mirounga leonina: A Functional Data Analysis Approach |
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Journal |
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Year |
2020 |
Publication |
Frontiers in Marine Science |
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Volume |
7 |
Issue |
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Pages |
595 |
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Abstract |
The diving behavior of southern elephant seals, Mirounga leonina, is investigated through the analysis of time-depth dive profiles. The originality of this work is to consider dive profiles as continuous curves. For this purpose, a Functional Data Analysis (FDA) approach is proposed for the shape analysis of a collection of dive profiles. Complexity of dive shapes is characterized by a mixture of three main shape variations accounting for about 80% of the entire variability: U or V shape, vertical depth variability during the bottom time, and skewed left or right. Model-based clustering allows the identification of eight dive shape clusters in a quick and automated way. Connection between shape patterns and classical descriptors, as well as the number of prey capture events, is achieved, showing that the clusters are coherent to specific foraging behaviors previously identified in the literature labeled as drift, exploratory and active dives. Finally, FDA is compared to classical methods relying on the computation of discrete dive descriptors. Results show that taking the shape of the dive as a whole is more resilient to corrupted or incomplete sampled data. FDA is, therefore, an efficient tool adapted for processing and comparing dive data with different sampling frequencies and for improving the quality and the accuracy of transmitted data. |
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1201 |
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ISSN |
2296-7745 |
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yes |
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Serial |
8009 |
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Author |
Sophie M. Dupont, Christophe Barbraud, Olivier Chastel, Karine Delord, Charline Parenteau, Cécile Ribout, Frédéric Angelier |
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Title |
Do repeated captures and handling affect phenotype and survival of growing Snow Petrel (Pagodroma nivea)? |
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Journal |
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Year |
2020 |
Publication |
Polar Biology |
Abbreviated Journal |
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Volume |
43 |
Issue |
6 |
Pages |
637-646 |
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Abstract |
In vertebrates, developmental conditions can affect not only fledging success but also the phenotype of the offspring, with potential long-term consequences on adult performance. However, surprisingly the potential impact of anthropogenic disturbance on developing chicks is rarely investigated, notably in Antarctic wildlife. In this study, we specifically investigated the effects of repeated nest visits, capture, and handling on offspring survival and several complementary offspring phenotypic traits in the Snow Petrel (Pagodroma nivea) chicks after thermal emancipation. We did not find any significant effect of our disturbance protocol on the morphology (body size, body mass, body condition), the physiology (breath rate, stress-induced corticosterone levels) and the behaviour (defense behaviour) of developing Snow Petrels. This specific disturbance protocol did not have any significant effect on chick survival, but there was a non-significant trend towards a lower survival for the disturbed group (p = 0.1006), which showed an especially high mortality during a period of repeated snow storms. To conclude, investigator disturbance seems to have little effect on Snow Petrel chicks after thermal emancipation, but to remain cautious, we recommend to avoid capture and handling of Snow Petrel chicks during or soon after inclement weather. |
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109 |
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ISSN |
1432-2056 |
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yes |
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7661 |
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Author |
Dorothée Ehrich, Niels M. Schmidt, Gilles Gauthier, Ray Alisauskas, Anders Angerbjörn, Karin Clark, Frauke Ecke, Nina E. Eide, Erik Framstad, Jay Frandsen, Alastair Franke, Olivier Gilg, Marie-Andrée Giroux, Heikki Henttonen, Birger Hörnfeldt, Rolf A. Ims, Gennadiy D. Kataev, Sergey P. Kharitonov, Siw T. Killengreen, Charles J. Krebs, Richard B. Lanctot, Nicolas Lecomte, Irina E. Menyushina, Douglas W. Morris, Guy Morrisson, Lauri Oksanen, Tarja Oksanen, Johan Olofsson, Ivan G. Pokrovsky, Igor Yu. Popov, Donald Reid, James D. Roth, Sarah T. Saalfeld, Gustaf Samelius, Benoit Sittler, Sergey M. Sleptsov, Paul A. Smith, Aleksandr A. Sokolov, Natalya A. Sokolova, Mikhail Y. Soloviev, Diana V. Solovyeva |
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Title |
Documenting lemming population change in the Arctic: Can we detect trends? |
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Journal |
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Year |
2020 |
Publication |
Ambio |
Abbreviated Journal |
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Volume |
49 |
Issue |
3 |
Pages |
786-800 |
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Keywords |
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Abstract |
Lemmings are a key component of tundra food webs and changes in their dynamics can affect the whole ecosystem. We present a comprehensive overview of lemming monitoring and research activities, and assess recent trends in lemming abundance across the circumpolar Arctic. Since 2000, lemmings have been monitored at 49 sites of which 38 are still active. The sites were not evenly distributed with notably Russia and high Arctic Canada underrepresented. Abundance was monitored at all sites, but methods and levels of precision varied greatly. Other important attributes such as health, genetic diversity and potential drivers of population change, were often not monitored. There was no evidence that lemming populations were decreasing in general, although a negative trend was detected for low arctic populations sympatric with voles. To keep the pace of arctic change, we recommend maintaining long-term programmes while harmonizing methods, improving spatial coverage and integrating an ecosystem perspective. |
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1036 |
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ISSN |
1654-7209 |
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yes |
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7646 |
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Author |
E. Aristidi, A. Agabi, L. Abe, E. Fossat, A. Ziad, D. Mékarnia |
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Title |
Dome C coherence time statistics from DIMM data |
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Journal |
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Year |
2020 |
Publication |
Monthly Notices of the Royal Astronomical Society |
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Volume |
496 |
Issue |
4 |
Pages |
4822-4826 |
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Keywords |
Astrophysics – Instrumentation and Methods for Astrophysics |
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Abstract |
We present a reanalysis of several years of DIMM data at the site of Dome C, Antarctica, to provide measurements of the coherence time $\tau0$. Statistics and seasonal behaviour of $\tau0$ are given at two heights above the ground, 3m and 8m, for the wavelength $\lambda=500$nm. We found an annual median value of $2.9$ms at the height of 8m. A few measurements could also be obtained at the height of 20m and give a median value of 6ms during the period June--September. For the first time, we provide measurements of $\tau0$ in daytime during the summer, which appears to show the same time dependence as the seeing with a sharp maximum at 5pm local time. Exceptional values of $\tau0$ above 10ms are met at this particular moment. The continuous slow variations of turbulence conditions during the day offers a natural test bed for a solar adaptive optics system. |
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1066 |
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ISSN |
0035-8711, 1365-2966 |
ISBN |
0035-8711, 1365-2966 |
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yes |
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7825 |
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Author |
Najat Bhiry, Dominique Marguerie, Tommy Weetaluktuk, Pierre M. Desrosiers, Dominique Todisco, Myosotis Desroches Bourgon, David Aoustin |
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Title |
Dorset and Thule Inuit occupations of Qikirtajuaq (Smith Island), Nunavik, Canada: a palaeoecological approach |
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Journal |
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Year |
2020 |
Publication |
Boreas |
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Volume |
50 |
Issue |
3 |
Pages |
826-843 |
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Abstract |
Qikirtajuaq is a long island facing the Inuit village of Akulivik on the northeastern coast of Hudson Bay (Canada) that is rich in archaeological sites. Kangiakallak-1 (JeGn-2), one of the main sites on this island, is a large multicomponent site that includes Dorset and Thule Inuit winter houses. This study documents the dynamics of palaeoenvironmental conditions in the successive occupations of the Kangiakallak-1 settlement based on plant macrofossils, pollen and non-pollen palynomorph analyses and archaeological research. The data indicate that Dorset inhabitants constructed their dwelling at about 772 cal. a BP. The site was reused by the Thule Inuit a few decades later, starting at about 671 cal. a BP. Thus, Kangiakallak-1 is one of the few sites, at least in Nunavik (northern Québec, Canada), that were rapidly reoccupied by the Thule Inuit after the departure of the Dorset inhabitants, which indicates a possible overlap between the two cultures in the Akulivik region. The palaeoecological data show that both Dorset and Thule inhabitants left clear footprints at the local scale in the form of several nitrophilous species that became established in and near the houses and persisted over a long period. The deposition of domestic waste (including bone fragments, skin, burnt fat and charcoal fragments) inside the subterranean dwellings fertilized the soil and led to the growth of unique nitrophilous plants. These changes transformed the houses into exceptional floristic refuges. |
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1080 |
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1502-3885 |
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yes |
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8292 |
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Author |
Charles Amory |
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Title |
Drifting-snow statistics from multiple-year autonomous measurements in Adélie Land, East Antarctica |
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Year |
2020 |
Publication |
The Cryosphere |
Abbreviated Journal |
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Volume |
14 |
Issue |
5 |
Pages |
1713-1725 |
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Abstract |
Drifting snow is a widespread feature over the Antarctic ice sheet, whose climatological and hydrological significance at the continental scale have been consequently investigated through modelling and satellite approaches. While field measurements are needed to evaluate and interpret model and satellite products, most drifting-snow observation campaigns in Antarctica involved data collected at a single location and over short time periods. With the aim of acquiring new data relevant to the observation and modelling of drifting snow in Antarctic conditions, two remote locations in coastal Adélie Land (East Antarctica) that are 100 km apart were instrumented in January 2010 with meteorological and second-generation IAV Engineering acoustic FlowCapt™ sensors. The data, provided nearly continuously so far, constitute the longest dataset of autonomous near-surface (i.e. within 2 m) measurements of drifting snow currently available over the Antarctic continent. This paper presents an assessment of drifting-snow occurrences and snow mass transport from up to 9 years (2010–2018) of half-hourly observational records collected in one of the Antarctic regions most prone to snow transport by wind. The dataset is freely available to the scientific community and can be used to complement satellite products and evaluate snow-transport models close to the surface and at high temporal frequency. |
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1013 |
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1994-0416 |
ISBN |
1994-0416 |
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yes |
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Call Number |
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Serial |
8071 |
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