11. Characterizing the groundwater flow regime in a landslide recharge area using stable isotopes: a case study of the Urbas landslide area in NW SloveniaKatja Koren, Luka Serianz, Mitja Janža, 2022, original scientific article Abstract: Slope stability strongly depends on the prevailing hydrological and hydrogeological conditions. The amount and intensity of precipitation and changing groundwater levels are important landslide triggering factors. Environmental tracers, including the chemical and stable isotope compositions of precipitation and groundwater, were used to gain insight into the groundwater dynamics of the Urbas landslide. The landslide is situated in a mountainous area with steep slopes and high precipitation amount and poses a high risk for the safety of the Koroška Bela settlement that lies downstream. The stable isotope analyses of oxygen-18 (18O) and deuterium (2H) in the precipitation and groundwater were used to estimate the groundwater mean residence time and the average altitude of the landslide recharge area. This information will help to plan and prioritize remedial landslide measures aiming to reduce the recharge of the landslide body and, thus, lower the risk of transformation of the sliding material into debris flow. The results of the chemical analysis of samples taken from springs and a piezometer show a Ca–HCO3 water type. This indicates low water–rock interaction in a landslide area composed of Upper Carboniferous and Permian clastic rocks and points to upper laying carbonate rocks and scree deposits as the main recharge area. Water samples for stable isotope analyses of δ18O and δ2H were collected from a rain gauge, springs, and a piezometer over a two-year period (2018–2020). The estimated mean recharge altitude of the groundwater at sampling points was from approximately 1700 to 1800 m a.s.l. with a mean residence time of 2–5 months.
Keywords: landslide, groundwater, stable isotopes, oxygen-18, deuterium, hydrogeology, recharge dynamic
Published in DiRROS: 16.03.2022; Views: 746; Downloads: 309
 Full text (3,55 MB) |
12. Using stable isotopes and major ions to identify recharge characteristics of the Alpine groundwater-flow dominated Triglavska Bistrica RiverLuka Serianz, Sonja Cerar, Polona Vreča, 2021, original scientific article Abstract: Triglavska Bistrica is a typical Alpine river in the north-western part of Slovenia. Its recharge area includes some of the highest peaks in the Julian Alps. The hydrogeological conditions and flow of the river depend largely on groundwater exchange between the karstified aquifer in the carbonate rocks and the intergranular aquifer in the glaciofluvial deposits. The average volume of the river flow is up to several m3/s. In this study, water samples from different locations along the river were analysed for stable isotope ratios of oxygen and hydrogen, major ions, and concentration of tritium activity. The correlation of major ions suggests that the recharge area consists of both limestone and dolomite rocks. The δ18O and δ2H values decrease downstream, implying that the average recharge elevation increases. At the downstream sampling site V-5, located approx. 300 m upstream from the confluence of the Sava Dolinka River, the calculated mean recharge altitude is estimated to be 1,996 m.
Keywords: groundwater, oxygen and hydrogen isotopes, hydrogeochemistry, recharge area, Alpine aquifer, Slovenia
Published in DiRROS: 09.03.2022; Views: 875; Downloads: 295
Full text (3,01 MB) |
13. Stand up to excite the spine : neuromuscular, autonomic, and cardiometabolic responses during motor imagery in standing vs. sitting postureSidney Grosprêtre, Uroš Marušič, Philippe Gimenez, Gael Ennequin, Laurent Mourot, Laurie Isacco, 2021, original scientific article Abstract: Motor imagery (MI) for health and performance strategies has gained interest in recent decades. Nevertheless, there are still no studies that have comprehensively investigated the physiological responses during MI, and no one questions the influence of low-level contraction on these responses. Thus, the aim of the present study was to investigate the neuromuscular, autonomic nervous system (ANS), and cardiometabolic changes associated with an acute bout of MI practice in sitting and standing condition. Twelve young healthy males (26.3 % 4.4 years) participated in two experimental sessions (control vs. MI) consisting of two postural conditions (sitting vs. standing). ANS, hemodynamic and respiratory parameters, body sway parameters, and electromyography activity were continuously recorded, while neuromuscular parameters were recorded on the right triceps surae muscles before and after performing the postural conditions. While MI showed no effect on ANS, the standing posture increased the indices of sympathetic system activity and decreased those of the parasympathetic system (p < 0.05). Moreover, MI during standing induced greater spinal excitability compared to sitting posture (p < 0.05), which was accompanied with greater oxygen consumption, energy expenditure, ventilation, and lower cardiac output (p < 0.05). Asking individuals to perform MI of an isometric contraction while standing allows them to mentally focus on the motor command, not challenge balance, and produce specific cardiometabolic responses. Therefore, these results provide further evidence of posture and MI-related modulation of spinal excitability with additional autonomic and cardiometabolic responses in healthy young men.
Keywords: heart rate, oxygen uptake, VO2, H-reflex, elektromyography
Published in DiRROS: 29.11.2021; Views: 791; Downloads: 782
Full text (1,82 MB)
This document has many files! More... |
14. A randomized crossover trial on the acute cardiovascular demands during flywheel exerciseDamir Zubac, Vladimir Ivančev, Zoran Valić, Rado Pišot, Cécil J. W. Meulenberg, Irhad Trozic, Nandu Goswami, Boštjan Šimunič, 2021, original scientific article Abstract: In a randomized crossover trial, we examined whether age plays a role in the mean arterial pressure (MAP) response during a vigorous flywheel exercise of varying load. We hypothesized that the magnitude of increase in the MAP during the flywheel exercise would increase in proportion to advancing age, thereby imposing a significant challenge to the cardiovascular system. A total of 30 participants of both sexes (age range from 20%55 y, 37% women) underwent a detailed medical examination, and their maximal oxygen uptake was determined. They performed a squat exercise (2 sets % 7 repetitions) on a flywheel ergometer at three randomly assigned moments of inertia set at 0.025, 0.05, and 0.075 kg m2, while the cardiovascular response was continuously recorded via a Task force monitor. Compared to the resting values, robust rises in the MAP were observed during all three flywheel loads, reaching the highest value of 179 % 4 mmHg (p = 0.001) during the highest load. In parallel, the cardiac index (cardiac output normalized by the body surface area) was two-fold greater during all the flywheel loads compared to rest, and at a high load, exclusively, the total peripheral resistance increased by 11% (p = 0.001). The rise in heart rate compensated for a load-dependent drop in the stroke index (stroke volume normalized by the body surface area). In our study population, no correlations were observed between the relative increase in the MAP and the participants% age for the three flywheel loads. The present findings suggest that the larger moments of inertia impose a substantial burden to the cardiovascular system, without apparent associated age-differences of the relative magnitude of MAP rise throughout the exercise.
Keywords: yo-yo exercise, oxygen uptake, muscles loading, blood pressure, krvni tlak, flow mediate dilation
Published in DiRROS: 05.07.2021; Views: 1083; Downloads: 1174
Full text (1,85 MB)
This document has many files! More... |
15. Independent infuence of age on heart rate recovery after flywheel exercise in trained men and womenDamir Zubac, Nandu Goswami, Vladimir Ivančev, Zoran Valić, Boštjan Šimunič, 2021, original scientific article Abstract: The present study examined whether differences in the heart rate recovery following flywheel exercise cessation were associated with differences in maximal oxygen uptake (VO2 max.), age and sex in trained adults. Eleven men (age range 22-49 years, VO2 max.=43.6 +/- 7.6 mL kg min -1) and ten women (age range 20-53 years, VO2 max.=38.0 +/- 5.7 mL kg min%1) were randomly assigned to complete a squat-exercise on the flywheel ergometer set at three different moments of inertia, while their cardiovascular responses were continuously monitored. During the flywheel exercise the mean arterial pressure rose by ~35 to 40% (p=.001), and the increment was more robust in men than women. The cardiac index was two-fold greater across both sexes compared to the baseline (p=.001), while the rise in heart rate (~144 bpm) was more pronounced in women to compensate for their load-dependent stroke index decline (p=.001). The load-independent time-course changes in heart rate recovery markers were comparable between the sexes. When these indicators were pooled, a stepwise regression revealed age as the only relevant predictor of both fast and slow components of the heart rate recovery (~30 of the shared variance explained, p=.014). The present data suggest that the heart rate recovery declines with age, irrespective of sex, or well-preserved cardiorespiratory fitness in moderately-trained adults.
Keywords: training, exercise, Yo-Yo exercise, flywheel, heart rate variability, total peripheral conductance, oxygen uptake kinetics
Published in DiRROS: 11.06.2021; Views: 967; Downloads: 892
Full text (1,64 MB)
This document has many files! More... |
16. Synthesis and advanced electrochemical characterization of multifunctional electrocatalytic composite for unitized regenerative fuel cellLeonard Moriau, Marjan Bele, Alen Vižintin, Francisco Ruiz-Zepeda, Urša Petek, Primož Jovanovič, Martin Šala, Miran Gaberšček, Nejc Hodnik, 2019, original scientific article Keywords: electrocatalysis, bifunctional electrocatalysts, oxygen evolution reaction, oxygen reduction reaction, IL-TEM, IL-SEM, EFC-ICP-MS
Published in DiRROS: 24.11.2020; Views: 1449; Downloads: 984
Full text (3,51 MB)
This document has many files! More... |
17. Comparison of Pt-Cu/C with benchmark Pt-Co/C : metal dissolution and their surface interactionsMatija Gatalo, Primož Jovanovič, Urša Petek, Martin Šala, Vid Simon Šelih, Francisco Ruiz-Zepeda, Marjan Bele, Nejc Hodnik, Miran Gaberšček, 2019, original scientific article Keywords: oxygen reduction reaction, proton exchange membrane fuel cell, platinum alloy, metal dissolution, electrochemical flow cell coupled to inductively coupled plasma mass spectrometer
Published in DiRROS: 23.11.2020; Views: 1448; Downloads: 1085
Full text (4,12 MB)
This document has many files! More... |
18. |
