Metalworking sites in Estonia during the 7th–17th centuries

Väitekirja elektrooline versioon ei sisalda publikatsiooneMineviku metallitöö kuulub nende valdkondade hulka, mille uurimisel on arheoloogia märkimisväärseks teadmiste allikaks. Minu väitekirja eesmärk on anda peamiselt arheoloogilise leiuainese põhjal uut informatsiooni Eesti metallitöö kohta 7.–17. sajandini. Selle perioodi jooksul toimus nii tehnoloogilisi kui poliitilisi arenguid, millest kõige murrangulisemaks võiks pidada 13. sajandi alguse vallutussõda, mille käigus liideti Eesti alad kristliku Euroopaga. Uute linnade loomisega hakkas siia saabuma ka läänes väljaõppe saanud käsitöölisi, kes tõid kaasa omad töövõtted ja tööriistad. Põhilise allikana käsitlen metallitööpaiku ja sealt pärinevaid tootmisjääke. Rauatöö uurimiseks on suurema tähelepanu all sepikojad, seal asunud ääsid ja sepistamiseks vajaminev raud. Kohaliku rauasulatuse ja sepikodade laialihajutatud paiknemismustri tõttu säilitas maasepikoda oma rauaaegse ilme 14. sajandini. Eriti suure tähelepanu all on 14.–17. sajandisse dateeritud Käku sepikojaase Saaremaal, kuna sealt tuli 2007.-2014. aastal välitööde käigus välja nelja järjestikuse sepikoja ehitusjäänuseid kui hulgaliselt leide. Juba Käku kõige varasem, 14.–15. sajandisse dateeritud, sepikoda meenutab oma põhiplaanilt ja ääsi ehitusviisilt pigem 14. sajandisse dateeritud Haapsalu linna sepikodasid kui 13.–14. sajandi algusesse dateeritud Paatsa maasepikoda, mis viitab maa ja linnaseppade traditsioonide ühtlustumisest. Metallograafiline analüüs Käku sepikoja rauakangidest andis aga teavet selle kohta, et kuidas käitlesid sepad toorrauda ja taaskasutati terasest tööriistu. Metallivalu puhul analüüsisin eelkõige metallisulatustiigleid, valamiskulpe ja valuvorme ning neis leiduvaid metallijääke kasutades nii portatiivset spektromeetrit (pXRF) kui skaneerivat elektronmikroskoopi (SEM-EDS). Selgus, et nooremal rauaajal oli nii hõbeda kui tina valamine koondunud linnamägedele ja maalinnadesse. Uuritud tiiglikatketest sisaldas 27% hõbeda jääke, mis näitab, et hõbedavalu oli laialt levinud. Peale ristisõda ning uute linnade rajamist asendas linnades tehtud metallivalu varasemalt linnamägedel ja maalinnades tehtud käsitöö. Linnadesse tuuakse ka imporditud tiigleid, kus muude jääkide hulgas on puhta kulla valamise jäägid, mis on kontrastiks rauaaegsele metallivalule.Archaeology can contribute greatly to our understanding of past metalworking. The main goal of this thesis is to provide new information on Estonian metalworking between the 7th–17th centuries, based on archaeological sources. During this period there were political changes and technological developments that impacted Estonian society. The most important event was the 13th century crusade, after which Estonia was brought into Christian Europe. Western craftsmen started to settle into Estonia with the founding of new towns, bringing new techniques and tools as they came. My main contribution is the study of metalworking sites and the analysis of their production waste. Smithies, forges, iron blooms and bars are all investigated to gain a better understanding of ferrous metalworking. Local iron production and the scattered locations of smithies retained the pre-crusade workshop layout up until the 14th century. The 14th–17th century smithy site of Käku was studied in detail and the excavations between 2007–2014 revealed the remains of four consecutive smithies and thousands of finds. The smithy of Käku more resembles the 14th century urban smithies at Haapsalu, than the 13th–14th century rural smithy of Paatsa, which indicates a convergence of rural and urban smithing traditions by the 14th–15th centuries. Metallographic analysis of iron blooms and bars from the smithy site of Käku provides insight into how the smiths processed bloomery iron and how steel tools were reused. The non-ferrous metalwork is studied via crucibles and casting moulds. The residue they contained was analysed with a portable spectrometer (pXRF) and a scanning electron microscope (SEM-EDS). The results show that in the 7th to early 13th centuries the casting of silver and tin took place at hill forts and strongholds. Silver residues were detected in 27% of the crucibles, which suggests that silver casting was common. After the crusade, the towns became the main centres for the casting and crafting that previously was undertaken in the fortified centres. Foreign craftsmen introduced imported crucibles that were more durable at high temperatures than crucibles made from local clay. A few of the studied crucibles had residues of pure gold, which indicates a higher level of specialist goldsmithing, compared to the work of pre-crusade craftsmen.https://www.ester.ee/record=b530132

Feeding behaviour of adult Centropages hamatus (Copepoda, Calanoida): Functional response and selective feeding experiments

The feeding behaviour of adults of the marine calanoid copepod Centropages hamatus was studied in laboratory experiments with ciliates and phytoplankton as food sources. The ingestion rate of algal (flagellates, diatoms) and ciliate prey (oligotrichs) as a function of prey concentration could be described by a Holling type III functional response. with close to zero ingestion rates at concentrations below 5 mu g Cl-1. In general, ingestion of ciliates was higher than ingestion of algae, and maximum feeding rates by adult males reached were half the feeding rates of adult females at prey concentrations exceeding 50 mu g Cl-1. When diatoms and ciliates were offered together C. hamatus (both sexes) fed exclusively on ciliates as long as they contributed with more than 5% to the mixture. This indicates the capability of active prey selection and switching between suspension feeding and ambush predation. Therefore, the feeding behaviour of adult C hamaths can be characterised as omnivorous with a preference for larger motile prey. This implies a trophic level above two, if there is a sufficient abundance of protozoan food available. (C) 2009 Elsevier B.V. All rights reserved

Käku sepikoda : arheoloogia väljas ja sees

http://tartu.ester.ee/record=b2652927~S1*es

Linking foraging strategies of marine calanoid copepods to patterns of nitrogen stable isotope signatures in a mesocosm study

The foraging modes of calanoid copepods differ in that stationary suspension-feeding is more easily detected by prey with strong escape responses (ciliates) than is ‘cruising’ or ‘ambushing’ feeding. Thus, the ability of a copepod to include heterotrophic prey in its diet may be associated with its foraging mode and, further, with its nitrogen stable isotope signature (δ15N). This is because a more carnivorous diet may be expected to result in a higher δ15N. We tested this hypothesis in a mesocosm study using a density gradient (0 to 80 ind. l-1) of calanoid copepods. We expected copepod δ15N to generally increase with decreasing copepod density because of increased food availability, and predicted stronger increases for cruising than for stationary suspension-feeding species. As an assemblage, copepods had a pronounced impact on the food web: diatoms and ciliates decreased, whereas nanoflagellates increased with increasing copepod density. As expected, Centropages hamatus, a cruising species, showed the strongest isotopic increase and also highest population growth at low copepod density, suggesting that it was the most efficient species in capturing ciliates. Temora longicornis, a stationary suspension-feeder, showed a uniform isotopic increase in all mesocosms, which we believe resulted from nutritional stress arising from poor feeding on both ciliates (too fast for ingestion by T. longicornis) and nanoflagellates (too small). However, Pseudocalanus elongatus, a species equally categorised as a stationary suspension-feeder, showed increases in its δ15N similar to those for C. hamatus. While this may indicate potential switching in its foraging mode, alternative explanations cannot be ruled out, partly because qualitative and quantitative aspects of trophic enrichment in our experiment could not be clearly separated. This study shows that consumer δ15N are difficult to interpret, even if potential food sources and aspects of the species’ biology are known, and thus emphasises the necessity for further laboratory studies to help better interpret zooplankton δ15N in the field

Advantage in Reading Lexical Bundles is Reduced in Non-Native Speakers

Formulaic sequences such as idioms, collocations, and lexical bundles, which may be processed as holistic units, make up a large proportion of natural language. For language learners, however, formulaic patterns are a major barrier to achieving native like competence. The present study investigated the processing of lexical bundles by native speakers and less advanced non-native English speakers using corpus analysis for the identification of lexical bundles and eye-tracking to measure the reading times. The participants read sentences containing 4-grams and control phrases which were matched for sub-string frequency. The results for native speakers demonstrate a processing advantage for formulaic sequences over the matched control units. We do not find any processing advantage for non-native speakers which suggests that native like processing of lexical bundles comes only late in the acquisition process