307 research outputs found

    Space-time behavior of single and bimanual rhythmical movements: Data and limit cycle model.

    Get PDF

    The relevance of glacier melt in the water cycle of the Alps: the example of Austria

    Get PDF
    This paper quantifies the contribution of glacier melt to river runoff from compilation and statistical interpretation of data from available studies based on observations or glacio- hydrological modelling for the region of Austria (Austrian Salzach and Inn river basin). A logarithmic fit between the glacier melt contribution and the relative glacierized area was found not only for the long-term mean glacier contributions but also for the glacier melt contribution during the extreme hot an dry summer of 2003. Interestingly, the mean contributions of glacier melt to river runoff do not exceed 15 % for both river catchments and are uncorrelated to glacierization for glacierization values >10 %. This finding, however, has to be seen in the light of the general precipitation increase with altitude for the study region which levels out the increase of absolute melt with glacierization thus resulting in the rather constant value of glacier melt contribution. In order to qualitatively proof this finding another approach has been applied by calculating the quotient <i>q</i><sub>A03</sub> of the mean monthly August runoff in 2003 and the long-term mean August runoff for 38 gauging stations in Austria. The extreme summer 2003 was worth to be analysed as from the meteorological and glaciological point of view an extraordinary situation was observed. During June and July nearly the entire snow-cover melted and during August mainly bare ice melt of glaciers contributed to runoff. The <i>q</i><sub>A03</sub> quotients were calculated between 0.32 for a non-glacierized and 2.0 for a highly glacierized catchment. Using the results of this study the mean and maximum possible glacier melt contribution of catchments can be estimated based on the relative glacierized area. It can also be shown that the found correlation of glacierized area and glacier melt contribution is applicable for the Drau basin where yet no results of modelled glacier melt contributions are available

    Coprophagous features in carnivorous Nepenthes plants: a task for ureases

    Get PDF
    Most terrestrial carnivorous plants are specialized on insect prey digestion to obtain additional nutrients. Few species of the genus Nepenthes developed mutualistic relationships with mammals for nitrogen supplementation. Whether dietary changes require certain enzymatic composition to utilize new sources of nutrients has rarely been tested. Here, we investigated the role of urease for Nepenthes hemsleyana that gains nitrogen from the bat Kerivoula hardwickii while it roosts inside the pitchers. We hypothesized that N. hemsleyana is able to use urea from the bats’ excrements. In fact, we demonstrate that 15N-enriched urea provided to Nepenthes pitchers is metabolized and its nitrogen is distributed within the plant. As ureases are necessary to degrade urea, these hydrolytic enzymes should be involved. We proved the presence and enzymatic activity of a urease for Nepenthes plant tissues. The corresponding urease cDNA from N. hemsleyana was isolated and functionally expressed. A comprehensive phylogenetic analysis for eukaryotic ureases, including Nepenthes and five other carnivorous plants’ taxa, identified them as canonical ureases and reflects the plant phylogeny. Hence, this study reveals ureases as an emblematic example for an efficient, low-cost but high adaptive plasticity in plants while developing a further specialized lifestyle from carnivory to coprophagy

    Endogenous oxytocin response to film scenes of attachment and loss is pronounced in schizophrenia

    Get PDF
    Oxytocin (OXT) is critically involved in the regulation of attachment and interpersonal function. In this study, emotional childrens movies were used to stimulate OXT secretion in patients with schizophrenia and healthy controls (HCs). Furthermore, associations of OXT levels with measures of attachment style (Psychosis Attachment Measure), childhood adversity (Childhood Trauma Questionnaire) and symptom severity [Positive and Negative Syndrome Scale (PANSS)] were considered. In 35 patients with schizophrenia and 35 matched HCs, radioimmunoassay with sample extraction was used to determine OXT plasma levels before and after viewing of movie scenes portraying emotional bonding and loss and compared to a non-emotional condition. Statistical analysis indicated lower baseline OXT levels in female patients than in all other groups. OXT reactivity during emotional movies was significantly higher in patients when compared to HCs. OXT reactivity during the control movie related to PANSS `general psychopathology. No significant associations appeared between baseline or induced OXT levels and other PANSS subscales, attachment style or childhood adversity in patients. Our findings suggest differences of baseline OXT and a higher OXT reactivity toward strong emotional stimuli in patients with schizophrenia, suggesting a role of OXT as a gender- and context-dependent modulator of socio-emotional function

    Linkage of cave-ice changes to weather patterns inside and outside the cave Eisriesenwelt (Tennengebirge, Austria)

    Get PDF
    The behaviour of perennial ice masses in karst caves in relation to the outside climate is still not well understood, though a significant potential of the cave-ice for paleo-climate reconstructions could be expected. This study investigates the relationship between weather patterns inside and outside the cave Eisriesenwelt (Austrian Alps) and ice-surface changes of the ice-covered part of the cave from meteorological observations at three sites (outside the cave, entrance-near inside and in the middle section of the cave) including atmospheric and ice surface measurements as well as an ablation stake network. Whereas ice loss in summer was a general feature from stake measurements for almost all measurement sites in the cave in 2007, 2008 and 2009 (values up to −15 cm yr<sup>−1</sup>), a clear seasonal signal of ice accumulation (e.g. in spring as expected from theory) was not observed. It is shown that under recent climate the cave ice mass balance is more sensitive to winter climate for the inner measurement site and sensitive to winter and summer climate for the entrance-near site. Observed ice surface changes can be well explained by cave atmosphere measurements, indicating a clear annual cycle with weak mass loss in winter due to sublimation, stable ice conditions in spring until summer (autumn for the inner measurement site) and significant melt in late summer to autumn (for the entrance-near site). Interestingly, surface ice melt did not contribute to ablation at the inner site. It is obvious from the spatial sample of ice surface height observations that the ice body is currently in rather balanced state, though the influence of show-cave management on ice mass-balance could not be clearly quantified (but a significant input on accumulation for some parts of the cave is rather plausible)

    Coprophagous features in carnivorous Nepenthes plants: A task for ureases

    Get PDF
    Most terrestrial carnivorous plants are specialized on insect prey digestion to obtain additional nutrients. Few species of the genus Nepenthes developed mutualistic relationships with mammals for nitrogen supplementation. Whether dietary changes require certain enzymatic composition to utilize new sources of nutrients has rarely been tested. Here, we investigated the role of urease for Nepenthes hemsleyana that gains nitrogen from the bat Kerivoula hardwickii while it roosts inside the pitchers. We hypothesized that N. hemsleyana is able to use urea from the bats' excrements. In fact, we demonstrate that 15N-enriched urea provided to Nepenthes pitchers is metabolized and its nitrogen is distributed within the plant. As ureases are necessary to degrade urea, these hydrolytic enzymes should be involved. We proved the presence and enzymatic activity of a urease for Nepenthes plant tissues. The corresponding urease cDNA from N. hemsleyana was isolated and functionally expressed. A comprehensive phylogenetic analysis for eukaryotic ureases, including Nepenthes and five other carnivorous plants' taxa, identified them as canonical ureases and reflects the plant phylogeny. Hence, this study reveals ureases as an emblematic example for an efficient, low-cost but high adaptive plasticity in plants while developing a further specialized lifestyle from carnivory to coprophagy

    The Virtual Teacher (VT) Paradigm: Learning New Patterns of Interpersonal Coordination Using the Human Dynamic Clamp

    Get PDF
    The Virtual Teacher paradigm, a version of the Human Dynamic Clamp (HDC), is introduced into studies of learning patterns of inter-personal coordination. Combining mathematical modeling and experimentation, we investigate how the HDC may be used as a Virtual Teacher (VT) to help humans co-produce and internalize new inter-personal coordination pattern(s). Human learners produced rhythmic finger movements whilst observing a computer-driven avatar, animated by dynamic equations stemming from the well-established Haken-Kelso-Bunz (1985) and Schöner-Kelso (1988) models of coordination. We demonstrate that the VT is successful in shifting the pattern co-produced by the VT-human system toward any value (Experiment 1) and that the VT can help humans learn unstable relative phasing patterns (Experiment 2). Using transfer entropy, we find that information flow from one partner to the other increases when VT-human coordination loses stability. This suggests that variable joint performance may actually facilitate interaction, and in the long run learning. VT appears to be a promising tool for exploring basic learning processes involved in social interaction, unraveling the dynamics of information flow between interacting partners, and providing possible rehabilitation opportunities

    Universal neural field computation

    Full text link
    Turing machines and G\"odel numbers are important pillars of the theory of computation. Thus, any computational architecture needs to show how it could relate to Turing machines and how stable implementations of Turing computation are possible. In this chapter, we implement universal Turing computation in a neural field environment. To this end, we employ the canonical symbologram representation of a Turing machine obtained from a G\"odel encoding of its symbolic repertoire and generalized shifts. The resulting nonlinear dynamical automaton (NDA) is a piecewise affine-linear map acting on the unit square that is partitioned into rectangular domains. Instead of looking at point dynamics in phase space, we then consider functional dynamics of probability distributions functions (p.d.f.s) over phase space. This is generally described by a Frobenius-Perron integral transformation that can be regarded as a neural field equation over the unit square as feature space of a dynamic field theory (DFT). Solving the Frobenius-Perron equation yields that uniform p.d.f.s with rectangular support are mapped onto uniform p.d.f.s with rectangular support, again. We call the resulting representation \emph{dynamic field automaton}.Comment: 21 pages; 6 figures. arXiv admin note: text overlap with arXiv:1204.546

    Apparent contradiction in the projected climatic water balance for Austria: wetter conditions on average versus higher probability of meteorological droughts

    Get PDF
    In this paper future changes of surface water availability in Austria are investigated. We use an ensemble of downscaled and bias-corrected regional climate model simulations of the EURO-CORDEX initiative under moderate mitigation (RCP4.5) and Paris Agreement (RCP2.6) emission scenarios. The climatic water balance and its components (rainfall, snow melt, glacier melt and atmospheric evaporative demand) are used as indicators of surface water availability, and we focus on different altitudinal classes (lowland, mountainous and high alpine) to depict a variety of processes in complex terrain. Apart from analysing the mean changes of these components, we also pursue a hazard risk approach by estimating future changes in return periods of meteorological drought events of a given magnitude as observed in the reference period. The results show, in general, wetter conditions over the course of the 21st century over Austria on an annual basis compared to the reference period 1981–2010 (e.g. RCP4.5 +107 mm, RCP2.6 +63 mm for the period 2071–2100). Considering seasonal differences, winter and spring are getting wetter due to an increase in precipitation and a higher fraction of rainfall as a consequence of rising temperatures. In summer only little changes in the mean of the climatic water balance conditions are visible across the model ensemble (e.g. RCP4.5 ±0 mm, RCP2.6 −2 mm for the period 2071–2100). On the contrary, by analysing changes in return periods of drought events, an increasing risk of moderate and extreme drought events during summer is apparent, a signal emerging within the climate system along with increasing warming.</p
    • …
    corecore