Search results for "PELE"
showing 10 items of 139 documents
2021
Abstract. Lignin oxidation products (LOPs) are widely used as vegetation proxies in climate archives, such as sediment and peat cores. The total LOP concentration, Σ 8, provides information on the abundance of vegetation, while the ratios C / V and S / V of the different LOP groups also provide information on the type of vegetation. Recently, LOP analysis has been successfully applied to speleothem archives. However, there are many open questions concerning the transport and microbial degradation of LOPs on their way from the soil into the cave system. These processes could potentially alter the original source-dependent LOP signals, in particular the C / V and S / V ratios, and thus compli…
Contrasting styles of deep-marine pyroclastic eruptions revealed from Axial Seamount push core records
2015
Abstract A comprehensive understanding of explosive basaltic eruption processes in the deep-sea relies upon detailed analysis and comparison of the variety of volcaniclastic lithologies on the seafloor, which has been challenged by insufficient sample recovery. A dedicated ROV-based sampling approach using long push cores offers an unparalleled opportunity to fully characterize the diversity of unconsolidated volcaniclastic lithofacies on a recently active seamount. Lithofacies from Axial Seamount record two styles of pyroclastic eruptions, strombolian and phreatomagmatic, at 1.5 km water depth. Strombolian eruptions are represented by abundant fluidal and highly vesicular (up to 50%) vitri…
A comparison of different methods for speleothem age modelling
2012
Abstract Speleothems, such as stalagmites and flowstones, can be dated with unprecedented precision in the range of the last 650,000 a by the 230Th/U-method, which is considered as one of their major advantages as climate archives. However, a standard approach for the construction of speleothem age models and the estimation of the corresponding uncertainty has not been established yet. Here we apply five age modelling approaches ( StalAge , OxCal, a finite positive growth rate model and two spline-based models) to a synthetic speleothem growth model and two natural samples. All data sets contain problematic features such as outliers, age inversions, large and abrupt changes in growth rate a…
Millennial-scale climate variability during the last 12.5 ka recorded in a Caribbean speleothem
2013
Abstract We present a speleothem stable oxygen isotope record for the last 12.5 ka based on two stalagmites from western Cuba. The δ18O signal is interpreted to represent past precipitation variability. Both stalagmites show a pronounced transition from higher δ18O values (indicating drier conditions) to more negative δ18O values (suggesting wetter conditions) between 10 and 6 ka. This transition is also visible in a planktonic δ18O record off Haiti. On orbital timescales, the δ18O value of Caribbean precipitation, thus, strongly resembles the oxygen isotope composition of Caribbean surface water. On millenial timescales, the speleothem δ18O record shows a high correlation to a North Atlant…
Evaporite karst in Italy: A review
2017
none 16 si Although outcropping rarely in Italy, evaporite (gypsum and anhydrite) karst has been described in detail since the early 20th century. Gypsum caves are now known from almost all Italian regions, but are mainly localised along the northern border of the Apennine chain (Emilia Romagna and Marche), Calabria, and Sicily, where the major outcrops occur. Recently, important caves have also been discovered in the underground gypsum mines in Piedmont. During the late 80s and 90s several multidisciplinary studies were carried out in many gypsum areas, resulting in a comprehensive overview, promoting further research in these special karst regions. More recent and detailed studies focused…
Energy and speleogenesis: Key determinants of terrestrial species richness in caves
2017
Abstract The aim of this study was to unravel the relative role played by speleogenesis (i.e., the process in which a cave is formed), landscape‐scale variables, and geophysical factors in the determination of species richness in caves. Biological inventories from 21 caves located in the southeastern Iberian Peninsula along with partial least square (PLS) regression analysis were used to assess the relative importance of the different explanatory variables. The caves were grouped according to the similarity in their species composition; the effect that spatial distance could have on similarity was also studied using correlation between matrices. The energy and speleogenesis of caves account…
C3aR un Cd11b proteīnu ekspresijas noteikšana smadzeņu prefrontālās garozas audos šizofrēnijas genotipa pelēm
2021
Šizofrēnija ir neiroattīstības slimība, kas skar 1% pasaules populācijas pieaugušo vecumā. Šizofrēnijas ārstēšanā izmanto neiroleptiķus, kuri pamatā ietekmē dopamīna un serotonīna līmeņa regulāciju smadzenēs. Diemžēl, šī medikamentu grupa ir efektīva tikai daļai pacientu. Pēdējo gadu pētījumi norāda gan uz GABA sistēmas, gan neiroiekaisuma kaskādes nozīmi šizofrēnijas patoģenēzē (Moslem et al., 2019). Šī darba mērķis ir noskaidrot C3aR un Cd11b ekspresiju kontroles grupas peļu un jaunizveidotā šizofrēnijas peļu genotipa prefrontālās smadzeņu garozas audu lizātos ar Western blot metodi. Rezultāti parāda, ka paraugiem, kuriem bija gēnu knock-out, attiecīgie proteīni netika ekspresēti, norādot…
The magnesium isotope record of cave carbonate archives
2012
Here we explore the potential of magnesium (&delta;<sup>26</sup>Mg) isotope time-series data as continental climate proxies in speleothem calcite archives. For this purpose, a total of six Pleistocene and Holocene stalagmites from caves in Germany, Morocco and Peru and two flowstones from a cave in Austria were investigated. These caves represent the semi-arid to arid (Morocco), the warm-temperate (Germany), the equatorial-humid (Peru) and the cold-humid (Austria) climate zones. Changes in the calcite magnesium isotope signature with time are compared against carbon and oxygen isotope records from these speleothems. Similar to other proxies, the non-trivial interaction of a …
Vene õppekeelega põhikooli õpilaste ja õpetajate hoiakud eestikeelse aineõppe suhtes vahetult enne 2007. aasta gümnaasiumireformi algust
2009
Artiklis uuritakse kvantitatiivselt üheksanda klassi õpilaste ja neid eesti keeles õpetanud pedagoogide hoiakuid osalise eestikeelse aineõppe suhtes ning analüüsitakse, millised tegurid soodustavad õpilaste positiivsete hoiakute kujunemist eesti õppekeele suhtes, pöörates erilist tähelepanu uuringus täheldatud erinevusele osa õppeaineid eesti keeles omandanud ja kõiki õppeaineid vene keeles õppinud põhikoolilõpetajate hoiakute vahel. Artikli lõpuosas vaadeldakse kvalitatiivselt eestikeelse aineõppe positiivseid ja negatiivseid mõjusid, näidatakse probleeme, millega eestikeelses aineõppes osalenud õpilased ja õpetajad on kokku puutunud, ning tutvustatakse nende pakutud võimalikke lahendusi. …
Peļu aktivitātes izmaiņas atklātā lauka testā pēc insulta modelēšanas
2020
Išēmisks insults var izraisīt gan neiroloģiskas izmaiņas, tai skaitā sensorimotorās funkcijas un izziņas traucējumus, gan uzvedības izmaiņas. Atklātā lauka tests tiek plaši izmantots, lai novērtētu un analizētu peļu spontāno jeb vispārējo lokomotoro aktivitāti. Bakalaura darba mērķis ir izvērtēt peļu aktivitāti sešus mēnešus pēc insulta modelēšanas, izmantojot atklātā lauka testu. Iegūtie rezultāti rāda, ka Stroke grupas peles uzrāda ievērojami lielāku aktivitāti, griežoties pretpulksteņrādītāja virzienā, salīdzinot gan ar Naive, gan ar Sham grupas pelēm, kas norāda uz insulta bojājumu kontralaterālajā pusē. Naive grupas pelēm ievērojami samazinās aktivitāte, salīdzinot ar pirmo testēšanas …