73 research outputs found

    Analytical solution for buckling of asymmetrically delaminated Reissner's elastic columns including transverse shear

    Get PDF
    The exact analytical solution of buckling in delaminated columns is presented. In order to investigate analytically the influence of axial and shear strains on buckling loads the geometrically exact beam theory is employed with no simplification of the governing equations. The critical forces are then obtained by the linearized stability theory. In the paper, we limit the studies to linear elastic columns with a single delamination, but with arbitrary longitudinal and vertical asymmetry of delamination and arbitrary boundary conditions. The studies of quantitative and qualitative influence of transverse shear are shown in detail and extensive results for buckling loads with respect to delamination length, thickness and longitudinal position are presented. (c) 2007 Elsevier Ltd. All rights reserved

    Vaginalni ultrazvok in endometrijski karcinom

    Get PDF

    Palaeomagnetic research on karst sediments in Slovenia

    Get PDF
    We have conducted palaeomagnetic and magnetostratigraphic research on karst sediments in Slovenia since 1997. More than 2,000 samples were taken and analysed in 36 different profiles at 21 locations in caves and on the surface. Standard palaeomagnetic analyses were used (thermal and alternating field demagnetisation, magnetic susceptibility measurements, etc.). There is no evidence of younger marine deposition than Eocene in the SW part of Slovenia. Younger sediments occur only in caves and very rarely on the karst surface (different soils and a few remains of terrigeneous sediments). Marine and terrestrial Tertiary to Plio–Quaternary deposition occurs in the SE and E Slovenia. Chronostratigraphy of cave sediments in SW Slovenia completed by Rado Gospodarič in the 1980s was based on Pleistocene warm/cold cycles. Later Th/U dating indicated that speleothems from different caves in Slovenia are older. New dating principally results from palaeomagnetism and magnetostratigraphy of cave sediments calibrated, in some sites, by Th/U, palaentological and geomorphological analyses. Calibrated data contributed to the reconstruction of speleogenesis, deposition in caves, and indirectly to the evolution of karst surfaces and succession of tectonic movements. The evolution of caves in the Slovenian territory took part within one post-Eocene karstification period. This period continues to the present, and can be subdivided into individual, but not well limited, phases related to Cenozoic palaeogeographical changes. The period contains distinct phases of massive deposition in caves with as yet still preserved sediments dated to about 5.4–4.1 Ma (Miocene–Pliocene), 3.6–1.8 Ma (Pliocene) and Quaternary, following the cessation of Miocene deposition in the Pannonian Basin in the central, E and SE Slovenia and post-Messinian evolution in the SW and W Slovenia

    Cave Sediments from Postojnska–Planinska Cave System (Slovenia): Evidence of Multi-Phase Evolution in Epiphreatic Zone

    Get PDF
    The Postojnska jama–Planinska jama cave system and number of smaller adjacent caves are developed in the Postojnski kras. These caves are located between two dextral strike-slip fault zones oriented in the Dinaric direction. The caves contain lith­ologically diversified cave fill, ranging from speleothems to allo­genic fluvial sediments. The allogenic clastic material is derived from a single source, Eocene siliciclastics of the Pivka Basin. Small differences in mineral/petrologic composition between the sediments can be attributed to different degrees of weather­ing in the catchment area and homogenization of source sedi­ments. Thick sequences of fine-grained laminated sediments, deposited from suspension are common. The depositional en­vironment was mostly calm, but not completely stagnant. Sucha sedimentary environment can be described as cave lacustrine, withdeposition from pulsed flow. The homogeneity of the pa­laeomagnetic data suggests rapid deposition by a number of short-lived single-flood events over a few thousand years. This depositional style was favourable for recording of short-lived excursions in the palaeomagnetic field. The sediments were originally not expected to be older than Middle Quaternary in age (i.e. about 0.4 Ma). Later numerical dating (Th/U and ESR) indicated ages older than 0.53 ka. New palaeomagnetic data from selected sedimentary profiles within the cave system detected normal polarization in muchof the profiles studied. Reverse polarized magnetozones, interpreted mostly as short-lived excursions of magnetic field, were detected in only a few places. Therefore, we interpreted most of the sediments as be­ing younger than 0.78 Ma, belonging to different depositional phases within the Brunhes chron. Palaeomagnetic properties of two profiles in caves intersected by the artificial tunnel be­tween Postojnska jama and Črna jama had reverse polarized magnetozones and of sediments in Zguba jama, may indicate an age muchgreater than 0.78 Ma. The cave system has evolved over a long period of time, governed by the functioning of Pla­ninsko polje in the relation to the evolution of the resurgence area in Ljubljana Moor further to the east. General stabilization of the hydrological system withlow hydraulic head led to the evolution of caves in epiphreatic and paragenetic conditions over a long time-span. Individual cave segments or passages were completely filled and exhumed several times during the evolution of the cave. Alternation of depositional and erosional phases may be connected withchanging conditions within the cave system, the functioning of the resurgence area, collapse, climatic change, tectonic movement and the intrinsic mecha­nisms of contact karst

    Fossil Vertebrates and Paleomagnetism Update of One of the Earlier Stages of Cave Evolution in the Classical Karst, Slovenia: Pliocene of Črnotiče II Site and Račiška Pečina Cave

    Get PDF
    For the first time in the Classical Karst, paleontological data enabled to match the magnetostratigraphic record precisely with the geomagnetic polarity timescale in two studied sites: (i) a series of speleothems alternating with red clays in Račiška pečina Cave (Matarsko podolje), and (ii) an unroofed paleocave of the Črnotiče II site (Podgorski kras Plateau) completely filled by fluvial clastic sediments covered by speleothems. The later sites are also characterized by a rich appearance of fossil tubes of autochthonous stygobiont serpulid Marifugia cavatica. The vertebrate record is composed mostly of enamel fragments of rodents and soricomorphs. Absence of rootless arvicolids as well as taxonomic composition of the mammalian fauna suggests the Pliocene age of both sites. For (i) Račiška pečina (with Apodemus, cf. Borsodia) it was estimated to middle to late MN17 (ca 1.8–2.4 Ma), while (ii) the assemblage from Črnotiče II (with Deinsdorfia sp., Beremedia fissidens, Apodemus cf. atavus, Rhagapodemus cf. frequens, Glirulus sp., Cseria sp.) is obviously quite older: MN15–MN16 (ca 3.0–4.1 Ma). In respect to congruence of biostratigraphic and paleomagnetic data and a reliable sedimentary setting of the samples we propose to apply the respective datum also as the time of one ancient speleogenetic phase in the Classical Karst

    Prevajalce poučujemo jezik drugače, mar ne?

    Get PDF
    Kompetenčni okvir EMT (2022) jezikovno zmožnost (v navezi s kulturno) opisuje kot temelj vseh drugih zmožnosti poklicnih prevajalcev. Njen razvoj je zato v ospredju bolonjskih dodiplomski prevajalskih programov, medtem ko za magistrske prevajalske programe Kompetenčni okvir EMT določa, da študenti za vpis potrebujejo visoko raven jezikovne zmožnosti v najmanj dveh delovnih jezikih oziroma raven učinkovitosti C1 ali več po Skupnem evropskem jezikovnem okviru (SEJO). Poučevanje maternega in tujega jezika prihodnjih prevajalcev (in tolmačev) bi moralo biti zato prilagojeno njihovim specializiranim potrebam, s čimer se v številnih pogledih uvršča v okvir jezikov stroke (Cerezo Herrero 2018, Koletnik 2019). Na Oddelku za prevodoslovje Univerze v Mariboru zato že od leta 2012 ob začetku študija preverjamo jezikovno zmožnost študentov angleškega programa, od leta 2013 pa tudi obseg besedišča, in rezultate upoštevamo pri načrtovanju jezikovnega pouka. Medtem ko so bile v preteklosti že objavljene delne analize uspešnosti tako prilagojenega poučevanja (prim. Koletnik 2020 v povezavi z razvijanjem prevajalske zmožnosti, Koletnik in Tement 2020 za razvijanje besedišča), celostna analiza doslej še ni bila izvedena. Prav tako je deziderat primerjava oziroma korelacija izhodiščne zmožnosti s splošnim uspehom študentov pri jezikovnih predmetih na prevajalskem študiju, ki jo prinaša pričujoči članek. Dosedanje analize so sicer pokazale, da se za dodiplomski prevajalski študij angleškega jezika na Univerzi v Mariboru odločajo študenti z visoko razvito jezikovno zmožnostjo, kar predstavlja dodaten izziv pri snovanju učnih aktivnosti in materialov, obenem pa je dobra popotnica za magistrski študij prevajanja in tolmačenja

    Križna jama (SW Slovenia): Numerical-and correlated-ages from cave bear-bearing sediments

    Get PDF
    Križna jama is a large river cave located between Loško and Cerkniško poljes under Križna gora Mount in southern Slo­venia. It has been known since the mid-19thcentury due to numerous cave bear finds. The cave is filled by complicated sequences of cave fluvial and lacustrine sediments, whichare recently partly eroded. We studied two paleontological exca­vations and profiles in the Medvedji rov to contribute to the solution of dating of bone-bearing lithological horizons. The Križna jama I profile consists of alternation of speleothem lay­ers (flowstone sheets withsmall stalagmites, sometimes within situ cemented Ursus gr. spelaeus bones) and fine-grained silici­clastics often withbones of cave bear. It can be correlated withthe upper part of the Križna jama II profile, but witha slightly less preserved stratigraphic record. Radiocarbon and U-series dates clearly indicate two different ages of cave bear thanato­cenoses in the Križna jama I profile: those above flowstone crusts were dated to ca. 47–45 ka by radiocarbon dating; those included in speleothem layers and clay interbeds are older than 94 ka (U-series date). The details of internal lithology, low thicknesses of layers and the state of bone preservation exclude expected sandwiching of younger layers into eroded/washed spaces among flowstones. Numerical dating excludes re-depo­sition of bear bones from older assemblage to sediments above flowstones. According to the paleomagnetic parameters (pre­vailing normal polarization), the deposition took place within the Brunhes Chron (< 780 ka). There were discovered in total four short-lived reverse excursions of the magnetic field. Ac­cording to U-series data, the upper one (profile I) might be correlated withthe Blake excursion. The lower ones are older than ca 190 ka and can be correlated withsome of the Jamaica-Pringle Falls, Namaku, Calabrian Ridge, Portuguese margin or Calabrian Ridge 1 excursions. Sediments in studied profiles were deposited during the Last Glacial (Weichselian), Eemian interglacial, Saalian glacial and Holsteinian interglacial

    Snežna jama (Slovenia): Interdisciplinary dating of cave sediments and implication for landscape evolution

    Get PDF
    AbstractCaves are important markers of surface evolution, since they are, as a general rule, linked with ancient valley bottoms by their springs. However, caves can only be dated indirectly by means of the sediments they contain. If the sediment is older than common dating methods, one has to use multiple dating approaches in order to get meaningful results. U/Th dating, palaeomagnetic analysis of flowstone and sediment profiles, cosmogenic dating of quartz pebbles, and mammalian dating allowed a robust estimate of speleogenesis, sediment deposition, climatic change at the surface, and uplift history on the Periadriatic fault line during the Plio-Pleistocene. Our dates indicate that Snežna jama was formed in the (Upper) Miocene, received its sedimentary deposits during the Pliocene in a rather low-lying, hilly landscape, and became inactive due to uplift along the Periadriatic and Sava faults and climatic changes at the beginning of the Quaternary. Although it is only a single cave, the information contained within it makes it an important site of the Southern Alps
    corecore