Isotopic partitioning by small mammals in the subnivium

In the Arctic, food limitation is one of the driving factors behind small mammal population fluctuations. Active throughout the year, voles and lemmings (arvicoline rodents) are central prey in arctic food webs. Snow cover, however, makes the estimation of their winter diet challenging. We analyzed the isotopic composition of ever-growing incisors from species of voles and lemmings in northern Finland trapped in the spring and autumn. We found that resources appear to be reasonably partitioned and largely congruent with phylogeny. Our results reveal that winter resource use can be inferred from the tooth isotopic composition of rodents sampled in the spring, when trapping can be conducted, and that resources appear to be partitioned via competition under the snow.Peer reviewe

From the History of Polish Academic Organisations in Lithuania

Liczna mniejszość polska w Republice Litewskiej w latach międzywojennych znalazła się w bardzo trudnej sytuacji. Wynikała ona z nieuregulowanych stosunków dyplomatycznych pomiędzy Litwą i Polską oraz nieprzyjaznego stosunku władz litewskich do mniejszości polskiej. W jej szeregach znajdowało się wiele młodych ludzi w wieku studenckim. W tym czasie liczne myśli ideowe i organizacyjne różnymi drogami docierały na Litwę Kowieńską z ośrodków akademickich Wilna. Dopiero jednak po utworzeniu uniwersytetu w Kownie wielu młodych Polaków podjęło studia na różnych wydziałach. W 1925 r. powstała również myśl założenia własnej organizacji skupiającej polską młodzież akademicką. Było to Zjednoczenie Polaków Studentów Uniwersytetu Litewskiego. Z tym faktem wiązano pewne nadzieje na jakąś formę pojednania polsko-litewskiego. Wynikało to z tego, że młodzież polska studiująca na Uniwersytecie w Kownie była bardziej podatna na taką współpracę niż starsze pokolenie rodaków. Odnieść to można również do poglądów i form pracy ideowej i organizacyjnej. Przykładem tego są różne poglądy oraz inicjatywy zmierzające do konsolidacji i zjednoczenia całego ruchu młodzieżowego, wynikające z położenia mniejszości polskiej na Litwie. Można to dostrzec śledząc ducha ideowego i przebieg dorocznych uroczystości i zjazdów polskiej młodzieży akademickiej Litwy. Z jej szeregów wyrosło wielu wybitnych działaczy, którzy zadania ruchu polskiego na Litwie widzieli nieco szerzej, niż utarte stereotypy powstałe w czasach sporu i konfliktów polsko-litewskich. Czołową rolę w tym odgrywało właśnie Zjednoczenie Polaków Studentów Uniwersytetu Litewskiego w Kownie (po 1930 r. Witolda Wielkiego). Organizacja ta odgrywała także ważną rolę w całym środowisku polskim na Litwie, w którym polska inteligencja była już znacznie zdziesiątkowana. Zjednoczenie miało również znaczącą pozycję na terenie Uniwersytetu w Kownie i wśród całej społeczności akademickiej na Litwie i poza jej granicami. Z szeregów młodzieży akademickiej wyrosło wielu znanych uczestników opozycji antysowieckiej i antyhitlerowskiej, którzy czynnie włączyli się do walki o sprawę polską. Po II wojnie światowej tych, którzy przeżyli, można było spotkać w Białymstoku, Gdańsku, Olsztynie, Toruniu, Warszawie czy Wrocławiu.In the period between the World Wars, the numerous Polish minority in the Republic of Lithuania (or Kaunas Lithuania, as Poles used to call it) found themselves in a very precarious position. It was due to severed diplomatic relations between Lithuania and Poland and the hostile attitude of the Lithuanian authorities towards the Polish residents. Many of the Poles in Lithuania were young people of university age. At that time, new ideological and organisational initiatives would reach the Republic of Lithuania through various channels from the academic centres of Vilnius (then in the Republic of Poland). However, it was only after the establishment of Kaunas University that many young Poles were admitted to various faculties. In 1925, an idea was put forward to establish an organisation for the Polish academic youth. This is how the Union of Polish Students of the University of Lithuania was formed. This fact raised hopes for some form of Polish-Lithuanian reconciliation. The Polish youth studying at the university in Kaunas were more eager to seek mutual collaboration than the older generation of compatriots. The same was true about the views and forms of ideological and organisational work. For example, a number of views and initiatives surfaced that aimed to consolidate and unite the entire youth movement around the situation of the Polish minority in Lithuania. This becomes evident when exploring the ideological spirit and programme of annual rallies and celebrations held by the Polish academic youth in Lithuania. The movement spawned many outstanding activists who tried to adopt a broader approach to of the Polish initiatives in Lithuania instead of narrowing them down to the usual stereotypes created in the time of Polish-Lithuanian dispute and conflicts. The leading role in this process was assumed by the Union of Polish Students of the University of Lithuania in Kaunas (in 1930 named after Duke Vytautas the Great). This organisation influenced the entire Polish community in Lithuania, whose intelligentsia had already been severely depleted. The union also enjoyed a significant position at the university in Kaunas as well as among the entire academic fraternity in Lithuania and abroad. Many merited participants of the anti-Soviet and anti-Nazi opposition struggling for the Polish cause in the following years were recruited from among the ranks of the academic youth. After WW2, the survivors settled in in Białystok, Gdańsk, Olsztyn, Toruń, Warsaw, and Wrocław

Association of the Polish academic youth in Lithuania in 1926-1938

Upon the institution of the Lithuanian University in Kowno (Kaunas), graduates of three Polish gymnasiums (in Kowno, Poniewież, Wiłkomierz) faced an opportunity to undertake higher education. At the same time, many young Poles who were born in Lithuania studied abroad, mostly in Austria, Belgium and France. For obvious reasons, they made attempts to establish their own organizations and associations. This trend was highly diverse in structural terms, which made it difficult to cooperate. In Kowno alone, three such establishments were created: Union of Polish Students of the Lithuanian University (now Vytautas Magnus University), the Students' Corporation "Lauda", and the Union of Polish Girl Students of the Lithuanian University "Znicz". Nonetheless, there were various establishments for Polish students from Lithuania, and this situation not only led to a fragmentation of Polish academia, but it even faced disintegration and internal disputes. This happened when the World Union of Poles Abroad (Warsaw) recommended that fellow Poles living abroad consolidate as much as possible and cooperate in one uniform system of organization. This idea, despite enmity between Poland and Lithuania, would reach as far as Kowno. Such an attempt was made despite some resistance from some youth activists in the latter half of the 1920s. It followed from the fear that other new organizations might appear and make it even more difficult to collaborate, whereas existing ones were not keen on relinquishing the autonomy they already had. In order to avoid this kind of controversy, the idea emerged to establish a federation that would not abolish existing student institutions, but would unite them in one principal organization. To this end, on 27-28 August 1927, a congress of Polish youth from Lithuania was organized. The event proved very successful because a new organization was established: the Union of Polish Academic Youth in Lithuania (ZPMAL). The basis of its functioning was defined by the statute, which consolidated all Polish university students living in Lithuania. As the central body, the Union was to coordinate common activities and safeguard the ideological profile of its members and take care of the Polish minority. While leaving the structure of existing units intact, the statute obliged their members to be members of the ZPMAL at the same time. Although the ZPMAL met all required changes stipulated in the statute, it was dissolved on 10 January 1938. Attempts at reversing this decision were ultimately rejected on 6 April 1938, and this date is regarded as the day of the final closure. Keywords: Poland; Lithuania; Kowno; Polish students; consolidation attempts

A mobility analysis of using the Rhex-type mobile robot in various surroundings

Mobile robots are becoming increasingly popular, finding a great deal of applications, especially in situations where conventional mobility systems, such as wheels or tracks, prove ineffective. Exploration of an unknown environment or a place, in which Man is incapable of staying, for example exploring remote planets in the Solar System, is often linked with operating a device in a rough terrain. This requires an adjustment of the robot locomotion system to the ground. The problem of high mobility in diverse surroundings is still a major challenge. Therefore, the concept of mobile robots is extremely popular and is still being developed. Using this type of propulsion carries several advantages, namely the possibility of applicability of this type of solutions in an environment, which is not easily accessible to wheeled vehicles (sandy, mountainous terrain, etc.). There is still a large interest of constructors and scientists in unconventional drive systems, adapted directly from nature, which often offers very efficient solutions. Quite frequently, designers copy the construction of animal locomotion system, attempting at implementing them in their designs. The aim of this article is to present an original construction, known as the Rhex-type robot in the available literature. In addition, it presents a number of conducted investigations, which describe the platform’s mobility in various terrains, such as sands, rocks and rubbles, as well as the possibility to overcome the terrain obstacles. It ends with conclusions and potential application areas of this type of a design

Potencjał hydroenergetyczny dolnej Wisły

This paper presents an estimate analysis of the hydropower potential of the lower Vistula River from Warsaw to Gdańsk Bay. The calculations were made for a hydraulic model of the lower Vistula which takes into account potential development of barrages in a cascade system. Results obtained from the model simulations and from hydrological calculations were used to estimate the power of hydropower plants and the average annual energy output from the entire cascade system. The results of calculations indicate significant energy benefits resulting from the development of a cascade of hydropower plants in the lower Vistula. This study does not discuss the cascade project’s economic viability or other aspects of its development (inland waterways, flood control, etc.).W artykule przedstawiono szacunkową analizę potencjału hydroenergetycznego dolnej Wisły na odcinku od Warszawy do Zatoki Gdańskiej. Obliczenia wykonano, przyjmując model hydrauliczny dolnej Wisły, w którym uwzględniono potencjalną zabudowę stopniami wodnymi pracującymi w układzie kaskady zwartej. Uzyskane wyniki symulacji z modelu wraz z przeprowadzonymi obliczeniami hydrologicznymi posłużyły do oszacowania mocy elektrowni wodnych oraz średniej rocznej produkcji energii całego układu kaskady. Otrzymane wyniki obliczeń wskazują na znaczące korzyści energetyczne wynikające z budowy kaskady elektrowni wodnych na dolnej Wiśle. W pracy nie podjęto ekonomicznej kwestii opłacalności wykonania analizowanej kaskady, jak również innych aspektów istnienia kaskady (żegluga śródlądowa, ochrona przeciwpowodziowa i inne)

Effect of vinyl-functional polysiloxanes on the flammability of composites filled with natural fibre

Prowadzone badania mają na celu poznanie wpływu winylo-funkcyjnych polisiloksanów o różnej strukturze na palność wypełniacza lignocelulozowego oraz przygotowanego kompozytu. W roli wypełniacza zastosowano włókno lniane, które zmodyfikowano polisiloksanami winylo-funkcyjnymi. Matrycę przygotowanych kompozytów stanowił polietylen (PE). Kompozyty przygotowano na wytłaczarce laboratoryjnej, a następnie zbadano ich palność przy użyciu mikrokalorymetru pirolizy i spalania (PCFC) oraz kalorymetru stożkowego.The studies are designed to investigate the effect of various structured vinyl-functional polysiloxanes on the flammability of lignocellulosic filler and prepared composite. In the role of the filler was used flax fibre which has been modified with vinyl-functional polysiloxanes. The matrix of prepared composites was polyethylene (PE). The composites were prepared on a laboratory mixing extruder and then tested for flammability using pyrolysis and combustion flow calorimeter (PCFC) and cone calorimeter