2019
Authors
Kamila S. Zając Bjørn Arild Hatteland Barbara Feldmeyer Markus Pfenninger Anna Filipiak Leslie Robert Noble Dorota Lachowska-CierlikAbstract
Arion vulgaris Moquin-Tandon, 1855 is regarded as one of the 100 most invasive species in Europe. The native distribution range of this species is uncertain, but for many years, the Iberian Peninsula has been considered as the area of origin. However, recent studies indicate that A. vulgaris probably originated from France. We have investigated the genetic structure of 33 European populations (Poland, Norway, Germany, France, Denmark, Switzerland) of this slug, based on two molecular markers, mitochondrial cytochrome c oxidase subunit I (COI, mtDNA) and nuclear zinc finger (ZF, nDNA). Our investigation included published data from two previous studies, giving a total of 95 populations of A. vulgaris from 26 countries. This comprehensive dataset shows comparable haplotype diversity in Central, North and Western Europe, and significantly lower haplotype diversity in the East. All haplotypes observed in the East can be found in the other regions, and haplotype diversity is highest in the Central and Western region. Moreover, there is strong isolation by distance in Central and Western Europe, and only very little in the East. Furthermore, the number of unique haplotypes was highest in France. This pattern strongly suggests that A. vulgaris has originated from a region spanning from France to Western Germany; hence, the slug is probably alien/invasive in other parts of Europe, where it occurs. Our results indicate the necessity to cover as much of the distribution range of a species as possible before making conclusive assumptions about its origin and alien status.
Authors
Junbin Zhao Sparkle Malone Steven Oberbauer Christina Staudhammer Gregory StarrAbstract
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Abstract
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Abstract
Preferential flow may become significant in partially frozen soils because infiltration can occur through large, initially air-filled pores surrounded by a soil matrix with limited infiltration capacity. The objectives of this study were to develop and evaluate a dual-permeability approach for simulating water flow and heat transport in macroporous soils undergoing freezing and thawing. This was achieved by introducing physically based equations for soil freezing and thawing into the dual-permeability model MACRO. Richards’ equation and the heat flow equation were loosely coupled using the generalized Clapeyron equation for the soil micropore domain. Freezing and thawing of macropore water is governed by a first-order equation for energy transfer between the micropore and macropore domains. We assumed that macropore water was unaffected by capillary forces, so that water in macropores freezes at 0°C. The performance of the model was evaluated for four test cases: (i) redistribution of water in the micropore domain during freezing, (ii) a comparison between the first-order energy transfer approach and the heat conduction equation, (iii) infiltration and water flow in frozen soil with an initially air-filled macropore domain, and (iv) thawing from the soil surface during constant-rate rainfall. Results show that the model behaves in accordance with the current understanding of water flow and heat transport in frozen macroporous soil. To improve modeling of water and heat flow in frozen soils, attention should now be focused on providing experimental data suitable for evaluating models that account for macropore flow.
Authors
Jihong Liu ClarkeAbstract
No abstract has been registered
Abstract
Synthetic Aperture Radar (SAR) data have gained interest for a variety of remote sensing applications, given the capability of SAR sensors to operate independent of solar radiation and day/night conditions. However, the radiometric quality of SAR images is hindered by speckle noise, which affects further image processing and interpretation. As such, speckle reduction is a crucial pre-processing step in many remote sensing studies based on SAR imagery. This study proposes a new adaptive de-speckling method based on a Gaussian Markov Random Field (GMRF) model. The proposed method integrates both pixel-wised and contextual information using a weighted summation technique. As a by-product of the proposed method, a de-speckled pseudo-span image, which is obtained from the least-squares analysis of the de-speckled multi-polarization channels, is also produced. Experimental results from the medium resolution, fully polarimetric L-band ALOS PALSAR data demonstrate the effectiveness of the proposed algorithm compared to other well-known de-speckling approaches. The de-speckled images produced by the proposed method maintainthe mean value of the original image in homogenous areas, while preserving the edges of features in heterogeneous regions. In particular, the equivalent number of look (ENL) achieved using the proposed method improves by about 15% and 47% compared to the NL-SAR and SARBM3D de-speckling approaches, respectively. Other evaluation indices, such as the mean and variance of the ratio image also reveal the superiority of the proposed method relative to other de-speckling approaches examined in this study.
Authors
Stig A. BorgvangAbstract
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Abstract
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Authors
Nick Hodgetts Marta Cálix Eve Englefield Nicholas Fettes M. García Criado Lea Patin Ana Nieto Ariel Bergamini Irene Bisang Elvira Baisheva Patrizio Campisi A Cogoni Tomas Hallingbäck Nadya A. Konstantinova Neil Lochhart Marko Sabovljevic Norbert Schnyder Christian Schröck Cecília Sérgio Manuela Sim-Sim Jaroslav Vrba Catarina C. Ferreira Olga M. Afonina T.L. Blockeel Hans Blom Steffen Caspari Rosalina Gabriel Cesar Garcia Ricardo Garilleti J González Mancebo Irina Goldberg Lars Hedenäs David T. Holyoak Vincent Hugonnot Sanna Huttunen Mikhail S. Ignatov Elena A. Ignatova Marta Infante Riikka Juutinen Thomas Kiebacher Heribert Köckinger Jan Kucera Niklas Lönnell Michael Lüth Anabela Martins Oleg Maslovsky Beata Papp Ron Porley Gordon Rothero Lars Söderström Sorin Ştefǎnuţ Kimmo Syrjänen Alain Untereiner Jíri Vána Alain Vanderpoorten Kai Vellak Michele Aleffi J. W. Bates Neil Bell Montserrat Brugués Nils Cronberg Jo Denyer J.G. Duckett Heinjo During Johannes Enroth Vladimir E. Fedosov Kjell Ivar Flatberg Anna Ganeva Piotr Gorski Urban Gunnarsson Kristian Hassel Helena Hespanhol Mark O. Hill Rory Hodd Kristoffer Hylander Nele Ingerpuu Sanna Laaka-Lindberg Francisco Lara Vicente Mazimpaka Anna Mežaka Frank Müller Jose David Orgaz Jairo Patiño Sharon Pilkington Felisa Puche Rosa Maria Ros Fred Rumsey José Gabriel Segarra-Moragues Ana Séneca Adam Stebel Risto Virtanen Henrik Weibull Jo Wilbraham Jan ZarnowiecAbstract
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Authors
Sigrid Bratlie Kristin Halvorsen Bjørn Kåre Myskja Hilde Mellegård Cathrine Bjorvatn Petter Frost Gunnar Harald Heiene Bjørn Morten Hofmann Arne Holst-Jensen Torolf Holst-Larsen Raino Sverre Malnes Benedicte Paus Bente Sandvig Sonja Irene Sjøli Birgit Skarstein May Britt Thorseth Nils Vagstad Dag Inge Våge Ole Johan BorgeAbstract
No abstract has been registered