New Algorithms for Position Heaps

We present several results about position heaps, a relatively new alternative to suffix trees and suffix arrays. First, we show that, if we limit the maximum length of patterns to be sought, then we can also limit the height of the heap and reduce the worst-case cost of insertions and deletions. Second, we show how to build a position heap in linear time independent of the size of the alphabet. Third, we show how to augment a position heap such that it supports access to the corresponding suffix array, and vice versa. Fourth, we introduce a variant of a position heap that can be simulated efficiently by a compressed suffix array with a linear number of extra bits

Long-term nutrient load management and lake restoration: Case of Säkylän Pyhäjärvi (SW Finland)

Eutrophication caused by anthropogenic nutrient pollution has become one of the most severe threats to water bodies. Nutrients enter water bodies from atmospheric precipitation, industrial and domestic wastewaters and surface runoff from agricultural and forest areas. As point pollution has been significantly reduced in developed countries in recent decades, agricultural non-point sources have been increasingly identified as the largest source of nutrient loading in water bodies. In this study, Lake Säkylän Pyhäjärvi and its catchment are studied as an example of a long-term, voluntary-based, co-operative model of lake and catchment management. Lake Pyhäjärvi is located in the centre of an intensive agricultural area in southwestern Finland. More than 20 professional fishermen operate in the lake area, and the lake is used as a drinking water source and for various recreational activities. Lake Pyhäjärvi is a good example of a large and shallow lake that suffers from eutrophication and is subject to measures to improve this undesired state under changing conditions. Climate change is one of the most important challenges faced by Lake Pyhäjärvi and other water bodies. The results show that climatic variation affects the amounts of runoff and nutrient loading and their timing during the year. The findings from the study area concerning warm winters and their influences on nutrient loading are in accordance with the IPCC scenarios of future climate change. In addition to nutrient reduction measures, the restoration of food chains (biomanipulation) is a key method in water quality management. The food-web structure in Lake Pyhäjärvi has, however, become disturbed due to mild winters, short ice cover and low fish catch. Ice cover that enables winter seining is extremely important to the water quality and ecosystem of Lake Pyhäjärvi, as the vendace stock is one of the key factors affecting the food web and the state of the lake. New methods for the reduction of nutrient loading and the treatment of runoff waters from agriculture, such as sand filters, were tested in field conditions. The results confirm that the filter technique is an applicable method for nutrient reduction, but further development is needed. The ability of sand filters to absorb nutrients can be improved with nutrient binding compounds, such as lime. Long-term hydrological, chemical and biological research and monitoring data on Lake Pyhäjärvi and its catchment provide a basis for water protection measures and improve our understanding of the complicated physical, chemical and biological interactions between the terrestrial and aquatic realms. In addition to measurements carried out in field conditions, Lake Pyhäjärvi and its catchment were studied using various modelling methods. In the calibration and validation of models, long-term and wide-ranging time series data proved to be valuable. Collaboration between researchers, modellers and local water managers further improves the reliability and usefulness of models. Lake Pyhäjärvi and its catchment can also be regarded as a good research laboratory from the point of view of the Baltic Sea. The main problem in both of them is eutrophication caused by excess nutrients, and nutrient loading has to be reduced – especially from agriculture. Mitigation measures are also similar in both cases.Ihmisen aiheuttamasta ravinnekuormituksesta johtuva rehevöityminen on yksi pahimmista vesistöjä uhkaavista ilmiöistä. Ravinteet kulkeutuvat vesiin ilmalaskeumana, teollisuuden ja yhdyskuntien jätevesissä sekä maatalous- ja metsäalueilta tulevissa valumavesissä. Kehittyneissä maissa pistekuormitus on merkittävästi vähentynyt viime vuosikymmeninä, ja hajakuormituksen, erityisesti maatalouden, on todettu olevan merkittävin vesistöjen ravinnekuormittaja. Tässä tutkimuksessa Säkylän Pyhäjärveä ja sen valuma-aluetta käytetään esimerkkinä pitkäjänteisestä, vapaaehtoisuuteen perustuvasta yhteistyömallista järven ja valuma-alueen vesien tilan parantamiseksi. Pyhäjärvi sijaitsee Lounais-Suomen intensiivisesti viljellyllä alueella. Järvellä toimii yli 20 ammattikalastajaa, sen vettä käytetään raakavetenä ja myös virkistyskäyttö on monipuolista ja intensiivistä. Pyhäjärvi on erinomainen esimerkki isosta, matalasta rehevöitymisen oireista kärsivästä järvestä, jonka tilaa pyritään määrätietoisesti parantamaan muuttuvissa olosuhteissa. Ilmastonmuutos on yksi suurimmista vesiensuojelun haasteista niin Pyhäjärvellä kuin muissakin vesistöissä. Tulokset osoittavat, että ilmastollinen vaihtelu vaikuttaa valunnan ja ravinnekuormituksen määriin sekä niiden vuodenaikaisuuksiin. Havainnot tutkimusalueelta koskien lämpimien talvien vaikutusta ravinnekuormitukseen ovat linjassa IPCC:n ilmastonmuutosskenaarioiden kanssa. Paitsi ravinnekuormituksen vähentäminen, myös ravintoketjukunnostus (biomanipulaatio) on keskeinen keino veden laadun hallinnassa. Ravintoketjun rakenne on kuitenkin häiriintynyt leutojen talvien, lyhyen jääpeiteajan ja vähäisen kalansaaliin vuoksi. Talvinuottauksen mahdollistavalla jääpeitteellä ja sen pituudella on suuri merkitys Pyhäjärven veden laadun ja ekosysteemin kannalta, sillä muikkukanta on yksi ravintoketjua ja järven tilaa säätelevistä tekijöistä. Ravinnekuormituksen vähentämiseksi ja maatalouden valumavesien käsittelemiseksi kehitettyjä uusia menetelmiä, esimerkiksi hiekkasuodattimia, on testattu kenttäolosuhteissa. Suodatintekniikka osoittautui käyttökelpoiseksi menetelmäksi ravinteiden vähentämiseksi, mutta kehitystyötä on edelleen jatkettava. Hiekkasuodattimien ravinteiden poistoa voidaan tehostaa erilaisilla ravinteita sitovilla yhdisteillä, esimerkiksi kalkkipohjaisilla materiaaleilla. Pyhäjärven ja sen valuma-alueen pitkäkestoiset hydrologiset, kemialliset ja biologiset seuranta- ja tutkimusaikasarjat ovat vesiensuojelun perusta ja niiden avulla lisätään ymmärrystä monimutkaisista järven ja valuma-alueen fysikaalisista, kemiallisista ja ekologisista vuorovaikutussuhteista. Kenttäolosuhteissa tehtyjen mittausten lisäksi Pyhäjärveä ja sen valuma-aluetta on tutkittu erilaisilla mallinnusmenetelmillä. Mallien kalibroinnissa ja validoinnissa pitkät ja monipuoliset aikasarjat osoittautuivat arvokkaiksi. Mallintajien, tutkijoiden ja käytännön vesiensuojelun toteuttajien yhteistyöllä voidaan edelleen parantaa mallien luotettavuutta ja hyödynnettävyyttä. Pyhäjärveä valuma-alueineen voidaan tarkastella myös Itämeren kaltaisena luonnonlaboratoriona. Ylimääräisten ravinteiden aiheuttama rehevöityminen on molempien ongelma, ja ravinnekuormitusta on molemmissa tapauksissa vähennettävä – erityisesti maataloudesta. Vähentämismenetelmät ovat niin ikään samoja.Siirretty Doriast

Finnish vatsa ~Sanskrit vatsá- and the formation of Indo-Iranian and Uralic languages

Finnish vatsa ‘stomach’ *-st-, with Greek and Balto-Slavic) and in the Indo-Aryan branch ( > *-tt-, probably due to Uralic substratum). The split of Indo-Iranian can be traced in the archaeological record to the differentiation of the Yamnaya culture in the North Pontic and Volga steppes respectively during the third millennium BCE, due to the use of separate sources of metal: the Iranian branch was dependent on the North Caucasus, while the Indo-Aryan branch was oriented towards the Urals. It is argued that the Abashevo culture of the Mid-Volga-Kama-Belaya basins and the Sejma-Turbino trade network (2200–1900 BCE) were bilingual in Proto-Indo-Aryan and PFU, and introduced the PFU as the basis of West Uralic (Volga-Finnic) into the Netted Ware Culture of the Upper Volga-Oka (1900–200 BCE).Peer reviewe

Development of the Surface Urban Energy and Water balance Scheme (SUEWS) for cold climate cities

The Surface Urban Energy and Water Balance Scheme (SUEWS) is developed to include snow. The processes addressed include accumulation of snow on the different urban surface types: snow albedo and density aging, snow melting and re-freezing of meltwater. Individual model parameters are assessed and independently evaluated using long-term observations in the two cold climate cities of Helsinki and Montreal. Eddy covariance sensible and latent heat fluxes and snow depth observations are available for two sites in Montreal and one in Helsinki. Surface runoff from two catchments (24 and 45 ha) in Helsinki and snow properties (albedo and density) from two sites in Montreal are also analysed. As multiple observation sites with different land-cover characteristics are available in both cities, model development is conducted independent of evaluation. The developed model simulates snowmelt related runoff well (within 19% and 3% for the two catchments in Helsinki when there is snow on the ground), with the springtime peak estimated correctly. However, the observed runoff peaks tend to be smoother than the simulated ones, likely due to the water holding capacity of the catchments and the missing time lag between the catchment and the observation point in the model. For all three sites the model simulates the timing of the snow accumulation and melt events well, but underestimates the total snow depth by 18–20% in Helsinki and 29–33% in Montreal. The model is able to reproduce the diurnal pattern of net radiation and turbulent fluxes of sensible and latent heat during cold snow, melting snow and snow-free periods. The largest model uncertainties are related to the timing of the melting period and the parameterization of the snowmelt. The results show that the enhanced model can simulate correctly the exchange of energy and water in cold climate cities at sites with varying surface cover