Per Möller
Professor
Administration
Jag har varit prefekt för gelogiska institutionen under 7 år (2000-2006) och trappade ner de administrativa sysslorna under 2007-2011 som biträdande prefekt med huvudsakligt ansvar för ekonomi- och budgetfrågor.
Grundutbildning
Som av facket glacialgeolog undervisar jag om glaciala sediment och landformer samt glacial utvecklingshistoria. Jag är inte heller främmande för tillämpade aspekter på kvartärgeologin som hydrogeologi, byggnadsgeologi och naturresursgeologi.
Forskning
Verksam som forskare och handledare inom två forskargrupper; (1) Glaciala processer, sediment och landformer och (2) Rekonstruktion av kvartära miljöer i arktiska/subarktiska områden - paleoglaciologi och paleoklimatologi. Mycket av mitt hjärta ligger i polarforskningen som jag bedrivit sedan 1989 på Grönland, Svalbard, Sibirien och Antarktis. Nyligen genomförda expeditioner har gått till Taymyrhalvön i Ryska Sibirien (2010, 2012) och Tierra del Fuego i sydligaste Sydamerika (2014). Mycket av pågående forskningsarbete centrerar dock kring drumlinbildning i Sverige samt glacial utvecklingshistoria för sydskandinavien. Det senare skall utredas genom kärnborrningar i mäktiga sedimentlagerföljder i Skåne och Småland, finansierat av SGU genom ett nyligen erhållet 3-årigt projektanslag.
Publikationer
Visar av publikationer. Sorterade efter år och sen titel.
A bowhead whale vertebra embedded in marine limit beach sediment on Barentsøya, Svalbard
Per Möller
(2024) Polar Research, 43
Artikel i tidskriftVentifacts and wind deflation surfaces in context with glaciofluvial sediment successions in southern Sweden – their age and implication for glacial history
Per Möller, Helena Alexanderson, Zoran Peric, Mayank Jain
(2024) Quaternary Science Reviews, 327
Artikel i tidskriftCoupled luminescence and cosmogenic nuclide dating of postglacial deflation surfaces and sand drift on a raised ice-contact delta at Veinge, SW Sweden
Helena Alexanderson, Per Möller, Mayank Jain, Mads F. Knudsen, Nicolaj Krog Larsen, et al.
(2024) Quaternary Geochronology, 80
Artikel i tidskriftVentifacts and wind deflation surfaces in context with glaciofluvial sediment successions in southern Sweden
Per Möller, Helena Alexanderson, Zoran Peric, Mayank Jain
(2024)
Konferensbidrag: abstractDeglaciation history and subsequent lake dynamics in the Siljan region, south-central Sweden - LiDAR evidence and sediment records
Per Möller, Svante Björck, T.P.F. Dowling, Dan Hammarlund, Martin Jakobsson, et al.
(2024)
Konferensbidrag: abstractLate glacial to Early Holocene deflation events and aeolian deposition on a raised ice-contact delta at Veinge, SW Sweden
Helena Alexanderson, Per Möller, Mayank Jain, Mads F. Knudsen, Nicolaj Krog Larsen, et al.
(2024)
Konferensbidrag: abstractSubstantial light woodland and open vegetation characterized the temperate forest biome before Homo sapiens
Elena A. Pearce, Florence F Mazier, Signe Normand, Corrie Bakels, Ralph Fyfe, et al.
(2023) Science Advances, 9
Artikel i tidskriftReply to: When did mammoths go extinct?
Yucheng Wang, Ana Prohaska, Haoran Dong, Adriana Alberti, Inger Greve Alsos, et al.
(2022) Nature, 612 p.4-6
Artikel i tidskriftDeglaciation history and subsequent lake dynamics in the Siljan region, south-central Sweden, based on new LiDAR evidence and sediment records
Per Möller, Svante Björck, T.P.F. Dowling, Dan Hammarlund, Martin Jakobsson, et al.
(2022) Earth Surface Processes and Landforms, 47 p.3515-3545
Artikel i tidskriftReconstructing the local landscape around a Mesolithic settlement site at Sammakko in Norrbotten, northern Sweden
Anne Birgitte Nielsen, Svante Björck, Per Möller
(2022) 11th European Palaeobotany and Palynology Conference Abstracts, Program and Proceedings
KonferensbidragLast interglacial sea-level proxies in the glaciated Northern Hemisphere
April S Dalton, Evan J. Gowan, Jan Mangerud, Per Möller, Juha Pekka Lunkka, et al.
(2022) Earth System Science Data, 14 p.1447-1492
Artikel i tidskriftLast interglacial (MIS 5e) sea level proxies in the glaciated Northern Hemisphere
April S. Dalton, Evan J. Gowan, Jan Mangerud, Per Möller, Juha Pekka Lunkka, et al.
(2022) Earth System Science Data, 14 p.1447-1492
PreprintRekonstruktion av paleomiljön för området kring den Mesolitiska stenåldersboplatsen vid Sammakko, Norrbotten
Per Möller, Anne Birgitte Nielsen, Svante Björck
(2022) Lundqua Report
RapportLate Quaternary Dynamics of Arctic Biota from Ancient Environmental Genomics
Yucheng Wang, Mikkel Winther Pedersen, Inger Greve Alsos, Bianca De Sanctis, Fernando Racimo, et al.
(2021) Nature, 600 p.86-92
Artikel i tidskriftRelative sea level changes and glacio-isostatic modelling in the Beagle Channel, Tierra del Fuego, Chile : glacial and tectonic implications
Svante Björck, Kurt Lambeck, Per Möller, Nicolas Waldmann, Ole Bennike, et al.
(2021) Quaternary Science Reviews, 251
Artikel i tidskriftMIS 3 sediment stratigraphy in southern Sweden sheds new light on the complex glacial history and dynamics across southern Scandinavia
Per Möller, Helena Alexanderson, JOHANNA ANJAR, Svante Björck
(2020) Boreas, 49 p.389-416
Artikel i tidskriftUnveiling the Ecological Applications of Ancient DNA from Mollusk Shells
Clio Der Sarkissian, Per Möller, Courtney Hofman,, Peter Ilsøe, Torben Rick, et al.
(2020) Frontiers in Ecology and Evolution, 8
Artikel i tidskriftData set on sedimentology, palaeoecology and chronology of Middle to Late Pleistocene deposits on the Taimyr Peninsula, Arctic Russia
Per Möller, Ivar Örn Benediktsson, JOHANNA ANJAR, Ole Bennike, Martin Bernhardson, et al.
(2019) Data in Brief, 25
Artikel i tidskriftGlacial history and palaeo-environmental change of southern Taimyr Peninsula, Arctic Russia, during the Middle and Late Pleistocene
Per Möller, Ívar Örn Benediktsson, JOHANNA ANJAR, Ole Bennike, Martin Bernhardson, et al.
(2019) Earth-Science Reviews, 196
Artikel i tidskriftA pre-LGM sandur at Fiskarheden in NW Dalarna, Sweden – sedimentology and glaciotectonic deformation.
Anne-Cecille Flindt, Helena Alexanderson, Ivar Örn Benediktsson, Per Möller
(2018) Boreas, 47 p.711-737
Artikel i tidskriftEquifinality in glacial geomorphology: instability theory examined via ribbed moraine and drumlins in Sweden
Per Möller, Thomas Dowling
(2018) GFF, 140 p.106-135
Artikel i tidskriftDrumlin formation: a mystery or not?
Anders Schomacker, Mark D. Johnson, Per Möller
(2018) GFF, 140 p.91-92
Artikel i tidskriftRapid subglacial streamlined bedform formation at a calving bay margin
Thomas Dowling, Per Möller, Matteo Spagnolo
(2016) Journal of Quaternary Science, 31 p.879-892
Artikel i tidskriftStreamlined subglacial bedforms on the Närke plain, south-central Sweden – areal distribution, morphometrics, internal architecture and formation
Per Möller, Thomas Dowling
(2016) Quaternary Science Reviews, 146 p.182-215
Artikel i tidskriftA Younger Dryas re-advance of local glaciers in North Greenland
Nicolaj Larsen, Svend Funder, Henriette Linge, Per Möller, Anders Schomacker, et al.
(2016) Quaternary Science Reviews, 147 p.47-58
Artikel i tidskriftMorphometry and core type of streamlined bedforms in southern Sweden from high resolution LiDAR
Tom Dowling, Matteo Spagnolo, Per Möller
(2015) Geomorphology, 236 p.54-63
Artikel i tidskriftThe Taimyr Peninsula and the Severnaya Zemlya archipelago, Arctic Russia : a synthesis of glacial history and palaeo-environment change during the last glacial cycle (MIS 5e-2)
Per Möller, Helena Alexanderson, Svend Funder, Christian Hjort
(2015) Quaternary Science Reviews, 107 p.149-181
Artikel i tidskriftThe importance of thermal boundary transitions on glacial geomorphology; mapping of ribbed/hummocky moraine and streamlined terrain from LiDAR, over Småland, South Sweden
Per Möller, Tom Dowling
(2015) GFF, 137 p.252-283
Artikel i tidskriftDrumlinised glaciofluvial and glaciolacustrine sediments on the Småland peneplain, South Sweden – new evidence on the growth and decay history of the Fennoscandian Ice Sheets during MIS 3
Per Möller, Andrew Murray
(2015) Quaternary Science Reviews, 122 p.1-29
Artikel i tidskriftUndersökning av kalciumkarbonatförekomsten i Vombfältet
Sandra Andersson Andersson, Per Möller, Linda Parkefelt, Kenneth M Persson
(2015) Vatten: tidskrift för vattenvård /Journal of Water Management and research, 71 p.17-26
Artikel i tidskriftWeichselian history of the Fennoscandian ice sheet in southern Sweden and the southwestern Baltic Basin
Johanna Anjar, Lena Adrielsson, Nicolaj Larsen, Per Möller, Kilian Barth
(2014) Boreas, 43 p.608-626
Artikel i tidskriftFifty thousand years of arctic vegetation change and megafauna diet
E Willerslev, J Davison, M Moora, E Zobel, E Coissac, et al.
(2014) Nature, 506 p.47-47
Artikel i tidskriftA 10Be-based reconstruction of the last deglaciation in southern Sweden
Johanna Anjar, Nicolaj Krog Larsen, Lena Håkansson, Per Möller, Henriette Linge, et al.
(2014) Boreas, 43 p.132-148
Artikel i tidskriftAn Arctic perspective on dating Mid-Late Pleistocene environmental history
Helena Alexanderson, J Backman, T M Cronin, S Funder, Ó Ingólfsson, et al.
(2014) Quaternary Science Reviews, 92 p.9-31
Artikel i tidskriftArctic ocean glacial history
M Jakobsson, K Andreassen, L R Bjarnardóttir, D Dove, J A Dowdeswell, et al.
(2014) Quaternary Science Reviews, 92 p.40-67
Artikel i tidskriftEemian and Early Weichselian environments in southern Sweden : a multi-proxy study of till-covered organic deposits from the Småland peneplain
Geoffrey Lemdahl, Anna Broström, Lars Hedenäs, Kristina Arvidsson, Sofia Holmgren, et al.
(2013) Journal of Quaternary Science, 28 p.705-719
Artikel i tidskriftLiving at the margin of the retreating Fennoscandian ice sheet : the early mesolithic sites at Aareavaara, northernmost Sweden
Per Möller, Olof Östlund, Lena Barnekow, Per Sandgren, Frida Palmbo, et al.
(2013) The Holocene, 23 p.104-116
Artikel i tidskriftThe new high-resolution LiDAR digital height model (‘Ny Nationell Höjdmodell’) and its application to Swedish Quaternary geomorphology
Tom Dowling, Helena Alexanderson, Per Möller
(2013) GFF, 135 p.145-151
Artikel i tidskriftAn OSL-dated sediment sequence at Idre, west-central Sweden, indicates ice-free conditions in MIS 3
Per Möller, Johanna Anjar, Andrew Murray
(2013) Boreas, 42 p.25-42
Artikel i tidskriftA comparative study of ancient sedimentary DNA, pollen and macrofossils from permafrost sediments of Northern Siberia reveals long-term vegetational stability
Tine Jørgensen, J Haile, Per Möller, A Andreev, S Boessenkool, et al.
(2012) Molecular Ecology, 21 p.1989-2003
Artikel i tidskriftPalaeoenvironments in the southern Baltic Sea Basin during Marine Isotope Stage 3 : a multi-proxy reconstruction
Johanna Anjar, Lena Adrielsson, O Bennike, Svante Björck, Helena Filipsson, et al.
(2012) Quaternary Science Reviews, 34 p.81-92
Artikel i tidskriftIce extent on the Taymyr Peninsula in time and space
Per Möller
(2012) Årsbok 2012 / Yearbook 2012 , p.24-25
Del av eller Kapitel i bokIce extent in time and space on the Taymyr Peninsula, Arctic Siberia
Per Möller
(2011) Yearbook 2010 , p.40-41
Del av eller Kapitel i bokRekonstruktion av paleomiljön för området kring stenåldersboplatserna vid Aareavaara, Norrbotten – jägarboplatser vid randen av en inlandsis?!
Per Möller, Lena Barnekow, Per Sandgren
(2011) Lundqua Report
RapportGlacial history of the Taymyr Peninsula and the Severnaya Zemlya archipelago, Arctic Russia
Per Möller, Christian Hjort, Helena Alexanderson, Florian Sallaba
(2011) Developments in Quaternary Science, 15 p.373-384
Del av eller Kapitel i bokPaper II - Dirt, dates and DNA: OSL and radiocarbon chronologies of perennially-frozen sediments in Siberia, and their implications for sedimentary ancient DNA studies
L.J. Arnold, R.G. Roberts, R.D.E. MacPhee, J.S. Haile, J.S. Brock, et al.
(2011) Boreas, 40 p.417-445
Artikel i tidskriftA 10,000-year record of Arctic Ocean sea-ice variability - view from the Beach
S Funder, H Goose, H Jepsen, E Kaas, KH Kjær, et al.
(2011) Science, 333 p.747-750
Artikel i tidskriftMelt-out till and ribbed moraine formation: a case study from south Sweden
Per Möller
(2010) Sedimentary Geology, 232 p.161-180
Artikel i tidskriftLate Quaternary glaciation history of northernmost Greenland: evidence of shelf-based ice
Nicolaj Krog Larsen, K.H. Kjær, S. Funder, Per Möller, J.J.M. van der Meer, et al.
(2010) Quaternary Science Reviews, 29 p.3399-3414
Artikel i tidskriftEarly to middle Holocene valley glaciations on northernmost Greenland
Per Möller, Nicolaj Krog Larsen, K.H. Kjær, S. Funder, A. Schomacker, et al.
(2010) Quaternary Science Reviews, 29 p.3379-3398
Artikel i tidskriftGrimslöv-Ströbyhöjden: en lång istidshistoria
Per Möller
(2010) Skatelövskrönika 2010, 21 p.144-153
Del av eller Kapitel i bokSub-till sediments on the Småland peneplain : their age, and implications for south-Swedish glacial stratigraphy and glacial dynamics
Per Möller
(2010) Lundqua Report
RapportLate Quaternary glaciation history of Isla de los Estados, southeasternmost South America
Per Möller, Christian Hjort, Svante Björck, Jorge Rabassa, Juan Federico Ponce
(2010) Quaternary Research, 73 p.521-534
Artikel i tidskriftLate Pleistocene glacial history of Jameson Land, central East Greenland, derived from cosmogenic (10)Be and (26)Al exposure dating
Lena Håkansson, H. Alexandersson, Christian Hjort, Per Möller, J.P. Briner, et al.
(2009) Boreas, 38 p.244-260
Artikel i tidskriftAncient DNA reveals late survival of mammoth and horse in interior Alaska
J. Haile, D. Froese, R.D.E Macphee, R.G. Roberts, L.J. Arnold, et al.
(2009) Proceedings of the National Academy of Sciences, 106 p.22352-22357
Artikel i tidskriftLate Quaternary marine-based Kara Sea ice sheets: review of terrestrial stratigraphic data highlighting their formation
Ó. Ingólfsson, Per Möller, H. Lokrantz
(2008) Polar Research, 27 p.152-161
Artikel i tidskriftGlacial and palaeo-environmental history of the Cape Chelyuskin area, Arctic Russia
Per Möller, G Federov, M Pavlov, M.-S. Seidenkrantz, Charlotte Sparrenbom
(2008) Polar Research, 27 p.222-248
Artikel i tidskriftRibbed moraine formed by subglacial folding, thrust stacking and lee-side cavity infill
Mattias Lindén, Per Möller, Lena Adrielsson
(2008) Boreas, 37 p.102-131
Artikel i tidskriftEarly Holocene environments on the October Revolution Island, Severnaya Zemlya, Arctic Russia
A. A. Andreev, D.J. Lubinski, A.A. Bobrov, Ó. Ingólfsson, S.L. Forman, et al.
(2008) Palaeogeography, Palaeoclimatology, Palaeoecology, 267 p.21-30
Artikel i tidskriftInstantaneous end moraine and sediment wedge formation during the 1890 glacier surge of Brúarjökull, Iceland
Ivar Benediktsson, Per Möller, Ólafur Ingólfsson, Jaap van der Meer, Kurt Kjær, et al.
(2008) Quaternary Science Reviews, 27 p.209-234
Artikel i tidskriftWhere the northernmost world ends – field work on Johannes V. Jensen Land, northern Greenland, for resolving its glacial and palaeoenvironmental history – part 2
Per Möller
(2008) Swedish Polar Research Secretariat, Yearbook 2007 , p.101-105
Del av eller Kapitel i bokIsla de los Estados – Quaternary geology and palaeoclimatology at the end of the world
Svante Björck, Christian Hjort, Karl Ljung, Per Möller, Barbara Wohlfarth
(2007) Polarforskninssekretariatets Årsbok 2006 (Polarforskninssekretariatets Årsbok) , p.44-49
Del av eller Kapitel i bokWhere the northernmost world ends – field work on Johannes V. Jensen Land, northern Greenland, for resolving its glacial and palaeoenvironmental history
Per Möller
(2007) Polarforskningssekretariatets Årsbok 2006 , p.74-77
Del av eller Kapitel i bokA Holocene lacustrine record in the central North Atlantic: proxies for volcanic activity, short-term NAO mode variability, and long-term precipitation changes
Svante Björck, Tammy Rittenour, P Rosen, Z Franca, Per Möller, et al.
(2006) Quaternary Science Reviews, 25 p.9-32
Artikel i tidskriftSevernaya Zemlya, Arctic Russia: a nucleation area for Kara Sea ice sheets during the Middle to Late Quaternary
Per Möller, D. Lubinski, Ó. Ingólfsson, S.L Forman, M-S. Siedenkrantz, et al.
(2006) Quaternary Science Reviews, 25 p.2894-2936
Artikel i tidskriftConstraints on the Late Saalian to early Middle Weichselian ice sheet of Eurasia from field data and rebound modelling
Kurt Lambeck, Anthony Purcell, Svend Funder, Kurt Kjaer, Eiliv Larsen, et al.
(2006) Boreas, 35 p.539-575
Artikel i tidskriftRogen moraine: an example of glacial reshaping of pre-existing landforms
Per Möller
(2006) Quaternary Science Reviews, 25 p.362-389
Artikel i tidskriftHolocene shore displacement and deglaciation chronology in Norrbotten, Sweden
Mattias Lindén, Per Möller, Svante Björck, Per Sandgren
(2006) Boreas, 35 p.1-22
Artikel i tidskriftMarginal formation of De Geer moraines and their implications to the dynamics of grounding-line recession
Mattias Lindén, Per Möller
(2005) Journal of Quaternary Science, 20 p.113-133
Artikel i tidskriftThe periglacial climate and environment in northern Eurasia during the Last Glaciation
HW Hubberten, A Andreev, VI Astakhov, I Demidov, JA Dowdeswell, et al.
(2004) Quaternary Science Reviews, 23 p.1333-1357
Artikel i tidskriftLate quaternary ice sheet history of northern Eurasia
JI Svendsen, Helena Alexanderson, VI Astakhov, I Demidov, JA Dowdeswell, et al.
(2004) Quaternary Science Reviews, 23 p.1229-1271
Artikel i tidskriftIce-dammed lakes and rerouting of the drainage of northern Eurasia during the Last Glaciation
J Mangerud, M Jakobsson, Helena Alexanderson, V Astakhov, GKC Clarke, et al.
(2004) Quaternary Science Reviews, 23 p.1313-1332
Artikel i tidskriftQuaternary glacial and sea-level history of Severnaya Zemlya, Siberian high arctic: a record more than 250,000 years old
D. Lubinski, Per Möller, Ó. Ingólfsson
(2004) Polarforskningssekretariatets Årsbok , p.95-100
Del av eller Kapitel i bokWeichselian glaciation of the Taymyr Peninsula, Siberia
Christian Hjort, Per Möller, Helena Alexanderson
(2004) Quaternary Glaciations - Extent and Chronology. Part 1: Europe (Developements in Quaternary Science, 2A) , p.359-367
Del av eller Kapitel i bokGlacial and environmental history of Severnaya Zemlya, Siberian high arctic, during the last >130,000 years
Ó Ingólfsson, Per Möller
(2003) Polarforskningssekretariatets Årsbok , p.85-90
Del av eller Kapitel i bokDepositional history of the North Taymyr ice-marginal zone, Siberia - a landsystem approach
Helena Alexanderson, Lena Adrielsson, Christian Hjort, Per Möller, O Antonov, et al.
(2002) Journal of Quaternary Science, 17 p.361-382
Artikel i tidskriftThe north Taymyr ice-marginal zone, arctic Siberia—a preliminary overview and dating
Helena Alexanderson, Christian Hjort, Per Möller, O. Antonov, M. Pavlov
(2001) Global and Planetary Change, 31 p.427-445
Artikel i tidskriftWeichselian geology and palaeo-environmental history of the central Taymyr Peninsula, Siberia, indicating no glaciation during the last global glacial maximum
Per Möller, D. Yu. Bolshiyanov, Helena Bergsten
(1999) Boreas, 28 p.92-114
Artikel i tidskriftMaximum extent of the Eurasian ice sheets in the Barents and Kara Sea region during the Weichselian
John Inge Svendsen, Valery I. Astakhov, Dimitri Yu. Bolshiyanov, Igor Demidov, Julian A. Dowdeswell, et al.
(1999) Boreas, 28 p.92-114
Artikel i tidskriftAntarctic glacial history since the Last Glacial Maximum: an overview of the record on land
O. Ingolfsson, Christian Hjort, P A Berkman, Svante Björck, E Calhoun, et al.
(1998) Antarctic Science, 10 p.326-344
Artikel i tidskriftHolocene deglaciation and climate history of the northern Antarctic Peninsula region : a discussion of correlations between the Southern and Northern Hemispheres
Christian Hjort, Svante Björck, Ó Ingólfsson, Per Möller
(1998) , p.110-112
Konferensbidrag: abstractHolocene glacial history and sea level changes on James Ross Island, Antarctic Peninsula
Christian Hjort, Ólafur Ingólfsson, Per Möller, J M Lirio
(1997) Journal of Quaternary Science, 12 p.259-273
Artikel i tidskriftSubrecent moraine ridge formation on Cuff Cape, Victoria Land, Antarctica
Per Möller
(1995) Geografiska Annaler, Series A: Physical Geography, 77 p.83-94
Artikel i tidskriftThe Quaternary record of eastern Svalbard - an overview
Jon Y. Landvik, Christian Hjort, J Mangerud, Per Möller, Otto Salvigsen
(1995) Polar Research, 14 p.95-103
Artikel i tidskriftLate Weichselian to early Holocene sedimentation in a steep fjord/valley setting, Visdalen, Edgeøya, eastern Svalbard: glacial deposits, alluvial/colluvial-fan deltas and spit-platforms
Per Möller, O P Stubdrup, Christian Kronborg
(1995) Polar Research, 14 p.181-203
Artikel i tidskriftGravel and sand flotation: a sediment dispersal process important in certain nearshore environments
Per Möller, Ólafur Ingólfsson
(1994) Journal of Sedimentary Research, 64 p.894-898
Artikel i tidskriftGlacial history of interior Jameson Land, East Greenland
Per Möller, Christian Hjort, Lena Adrielsson, Otto Salvigsen
(1994) Boreas, 23 p.320-348
Artikel i tidskriftLate Quaternary glacial history of the west coast of Jameson Land, East Greenland
Per Möller, Ólafur Ingólfsson, Astrid Lyså, S Funder, Svante Björck
(1994) Boreas, 23 p.447-458
Artikel i tidskriftLate Weichselian environmental history in southeastern Sweden during the deglaciation of the Scandinavian ice sheet
Per Möller, Svante Björck
(1987) Quaternary Research, 28 p.1-37
Artikel i tidskriftMoraine morphology, till genesis and deglaciation pattern in the Åsnen area, South central Småland, Sweden
Per Möller
(1987) LUNDQUA Thesis, 20
Doktorsavhandling