TY - JOUR A1 - Kaya, Adem A1 - Freitag, Melina A. T1 - Conditioning analysis for discrete Helmholtz problems JF - Computers and mathematics with applications : an international journal N2 - In this paper, we examine conditioning of the discretization of the Helmholtz problem. Although the discrete Helmholtz problem has been studied from different perspectives, to the best of our knowledge, there is no conditioning analysis for it. We aim to fill this gap in the literature. We propose a novel method in 1D to observe the near-zero eigenvalues of a symmetric indefinite matrix. Standard classification of ill-conditioning based on the matrix condition number is not true for the discrete Helmholtz problem. We relate the ill-conditioning of the discretization of the Helmholtz problem with the condition number of the matrix. We carry out analytical conditioning analysis in 1D and extend our observations to 2D with numerical observations. We examine several discretizations. We find different regions in which the condition number of the problem shows different characteristics. We also explain the general behavior of the solutions in these regions. KW - Helmholtz problem KW - Condition number KW - Ill-conditioning KW - Indefinite KW - matrices Y1 - 2022 U6 - https://doi.org/10.1016/j.camwa.2022.05.016 SN - 0898-1221 SN - 1873-7668 VL - 118 SP - 171 EP - 182 PB - Elsevier Science CY - Amsterdam ER - TY - JOUR A1 - Choudhury, Arnab A1 - DeVine, Jessalyn A. A. A1 - Sinha, Shreya A1 - Lau, Jascha Alexander A1 - Kandratsenka, Alexander A1 - Schwarzer, Dirk A1 - Saalfrank, Peter A1 - Wodtke, Alec Michael T1 - Condensed-phase isomerization through tunnelling gateways JF - Nature : the international weekly journal of science N2 - Quantum mechanical tunnelling describes transmission of matter waves through a barrier with height larger than the energy of the wave(1). Tunnelling becomes important when the de Broglie wavelength of the particle exceeds the barrier thickness; because wavelength increases with decreasing mass, lighter particles tunnel more efficiently than heavier ones. However, there exist examples in condensed-phase chemistry where increasing mass leads to increased tunnelling rates(2). In contrast to the textbook approach, which considers transitions between continuum states, condensed-phase reactions involve transitions between bound states of reactants and products. Here this conceptual distinction is highlighted by experimental measurements of isotopologue-specific tunnelling rates for CO rotational isomerization at an NaCl surface(3,4), showing nonmonotonic mass dependence. A quantum rate theory of isomerization is developed wherein transitions between sub-barrier reactant and product states occur through interaction with the environment. Tunnelling is fastest for specific pairs of states (gateways), the quantum mechanical details of which lead to enhanced cross-barrier coupling; the energies of these gateways arise nonsystematically, giving an erratic mass dependence. Gateways also accelerate ground-state isomerization, acting as leaky holes through the reaction barrier. This simple model provides a way to account for tunnelling in condensed-phase chemistry, and indicates that heavy-atom tunnelling may be more important than typically assumed. Y1 - 2022 U6 - https://doi.org/10.1038/s41586-022-05451-0 SN - 0028-0836 SN - 1476-4687 VL - 612 IS - 7941 SP - 691 EP - 695 PB - Macmillan Publishers Limited, part of Springer Nature CY - London ER - TY - JOUR A1 - Bouamra, Marwa A1 - Zouhal, Hassane A1 - Ratel, Sébastien A1 - Makhlouf, Issam A1 - Bezrati, Ikram A1 - Chtara, Moktar A1 - Behm, David George A1 - Granacher, Urs A1 - Chaouachi, Anis T1 - Concurrent Training Promotes Greater Gains on Body Composition and Components of Physical Fitness Than Single-Mode Training (Endurance or Resistance) in Youth With Obesity JF - Frontiers in Physiology N2 - The prevalence of obesity in the pediatric population has become a major public health issue. Indeed, the dramatic increase of this epidemic causes multiple and harmful consequences, Physical activity, particularly physical exercise, remains to be the cornerstone of interventions against childhood obesity. Given the conflicting findings with reference to the relevant literature addressing the effects of exercise on adiposity and physical fitness outcomes in obese children and adolescents, the effect of duration-matched concurrent training (CT) [50% resistance (RT) and 50% high-intensity-interval-training (HIIT)] on body composition and physical fitness in obese youth remains to be elucidated. Thus, the purpose of this study was to examine the effects of 9-weeks of CT compared to RT or HIIT alone, on body composition and selected physical fitness components in healthy sedentary obese youth. Out of 73 participants, only 37; [14 males and 23 females; age 13.4 ± 0.9 years; body-mass-index (BMI): 31.2 ± 4.8 kg·m-2] were eligible and randomized into three groups: HIIT (n = 12): 3-4 sets×12 runs at 80–110% peak velocity, with 10-s passive recovery between bouts; RT (n = 12): 6 exercises; 3–4 sets × 10 repetition maximum (RM) and CT (n = 13): 50% serial completion of RT and HIIT. CT promoted significant greater gains compared to HIIT and RT on body composition (p < 0.01, d = large), 6-min-walking test distance (6 MWT-distance) and on 6 MWT-VO2max (p < 0.03, d = large). In addition, CT showed substantially greater improvements than HIIT in the medicine ball throw test (20.2 vs. 13.6%, p < 0.04, d = large). On the other hand, RT exhibited significantly greater gains in relative hand grip strength (p < 0.03, d = large) and CMJ (p < 0.01, d = large) than HIIT and CT. CT promoted greater benefits for fat, body mass loss and cardiorespiratory fitness than HIIT or RT modalities. This study provides important information for practitioners and therapists on the application of effective exercise regimes with obese youth to induce significant and beneficial body composition changes. The applied CT program and the respective programming parameters in terms of exercise intensity and volume can be used by practitioners as an effective exercise treatment to fight the pandemic overweight and obesity in youth. KW - weight loss KW - adolescents KW - high-intensity-interval training KW - resistance training KW - DXA KW - matched time Y1 - 2022 U6 - https://doi.org/10.3389/fphys.2022.869063 SN - 1664-042X VL - 13 SP - 1 EP - 16 PB - Frontiers CY - Lausanne, Schweiz ER - TY - JOUR A1 - Thieken, Annegret A1 - Mohor, Guilherme Samprogna A1 - Kreibich, Heidi A1 - Müller, Meike T1 - Compound inland flood events BT - different pathways, different impacts and different coping options JF - Natural hazards and earth system sciences : NHESS N2 - Several severe flood events hit Germany in recent years, with events in 2013 and 2016 being the most destructive ones, although dynamics and flood processes were very different. While the 2013 event was a slowly rising widespread fluvial flood accompanied by some severe dike breaches, the events in 2016 were fast-onset pluvial floods, which resulted in surface water flooding in some places due to limited capacities of the drainage systems and in destructive flash floods with high sediment loads and clogging in others, particularly in small steep catchments. Hence, different pathways, i.e. different routes that the water takes to reach (and potentially damage) receptors, in our case private households, can be identified in both events. They can thus be regarded as spatially compound flood events or compound inland floods. This paper analyses how differently affected residents coped with these different flood types (fluvial and pluvial) and their impacts while accounting for the different pathways (river flood, dike breach, surface water flooding and flash flood) within the compound events. The analyses are based on two data sets with 1652 (for the 2013 flood) and 601 (for the 2016 flood) affected residents who were surveyed around 9 months after each flood, revealing little socio-economic differences - except for income - between the two samples. The four pathways showed significant differences with regard to their hydraulic and financial impacts, recovery, warning processes, and coping and adaptive behaviour. There are just small differences with regard to perceived self-efficacy and responsibility, offering entry points for tailored risk communication and support to improve property-level adaptation. Y1 - 2022 U6 - https://doi.org/10.5194/nhess-22-165-2022 SN - 1561-8633 SN - 1684-9981 VL - 22 IS - 1 SP - 165 EP - 185 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Weithoff, Guntram A1 - Bell, Elanor Margaret T1 - Complex Trophic Interactions in an Acidophilic Microbial Community JF - Microorganisms N2 - Extreme habitats often harbor specific communities that differ substantially from non-extreme habitats. In many cases, these communities are characterized by archaea, bacteria and protists, whereas the number of species of metazoa and higher plants is relatively low. In extremely acidic habitats, mostly prokaryotes and protists thrive, and only very few metazoa thrive, for example, rotifers. Since many studies have investigated the physiology and ecology of individual species, there is still a gap in research on direct, trophic interactions among extremophiles. To fill this gap, we experimentally studied the trophic interactions between a predatory protist (Actinophrys sol, Heliozoa) and its prey, the rotifers Elosa woralli and Cephalodella sp., the ciliate Urosomoida sp. and the mixotrophic protist Chlamydomonas acidophila (a green phytoflagellate, Chlorophyta). We found substantial predation pressure on all animal prey. High densities of Chlamydomonas acidophila reduced the predation impact on the rotifers by interfering with the feeding behaviour of A. sol. These trophic relations represent a natural case of intraguild predation, with Chlamydomonas acidophila being the common prey and the rotifers/ciliate and A. sol being the intraguild prey and predator, respectively. We further studied this intraguild predation along a resource gradient using Cephalodella sp. as the intraguild prey. The interactions among the three species led to an increase in relative rotifer abundance with increasing resource (Chlamydomonas) densities. By applying a series of laboratory experiments, we revealed the complexity of trophic interactions within a natural extremophilic community. KW - acid mine drainage KW - extremophiles KW - food web KW - heliozoa KW - intraguild predation KW - mining lakes KW - Rotifera Y1 - 2022 U6 - https://doi.org/10.3390/microorganisms10071340 SN - 2076-2607 VL - 10 SP - 1 EP - 10 PB - MDPI CY - Basel, Schweiz ET - 7 ER - TY - JOUR A1 - Galhuber, Markus A1 - Michenthaler, Helene A1 - Heininger, Christoph A1 - Reinisch, Isabel A1 - Nössing, Christoph A1 - Krstic, Jelena A1 - Kupper, Nadja A1 - Moyschewitz, Elisabeth A1 - Auer, Martina A1 - Heitzer, Ellen A1 - Ulz, Peter A1 - Birner-Gruenberger, Ruth A1 - Liesinger, Laura A1 - Lenihan-Geels, Georgia Ngawai A1 - Oster, Moritz A1 - Spreitzer, Emil A1 - Chiozzi, Riccardo Zenezini A1 - Schulz, Tim J. A1 - Schupp, Michael A1 - Madl, Tobias A1 - Heck, Albert J. R. A1 - Prokesch, Andreas T1 - Complementary omics strategies to dissect p53 signaling networks under nutrient stress JF - Cellular and molecular life sciences N2 - Signaling trough p53is a major cellular stress response mechanism and increases upon nutrient stresses such as starvation. Here, we show in a human hepatoma cell line that starvation leads to robust nuclear p53 stabilization. Using BioID, we determine the cytoplasmic p53 interaction network within the immediate-early starvation response and show that p53 is dissociated from several metabolic enzymes and the kinase PAK2 for which direct binding with the p53 DNA-binding domain was confirmed with NMR studies. Furthermore, proteomics after p53 immunoprecipitation (RIME) uncovered the nuclear interactome under prolonged starvation, where we confirmed the novel p53 interactors SORBS1 (insulin receptor signaling) and UGP2 (glycogen synthesis). Finally, transcriptomics after p53 re-expression revealed a distinct starvation-specific transcriptome response and suggested previously unknown nutrient-dependent p53 target genes. Together, our complementary approaches delineate several nodes of the p53 signaling cascade upon starvation, shedding new light on the mechanisms of p53 as nutrient stress sensor. Given the central role of p53 in cancer biology and the beneficial effects of fasting in cancer treatment, the identified interaction partners and networks could pinpoint novel pharmacologic targets to fine-tune p53 activity. KW - p53 signaling KW - Nutrient stress KW - Starvation KW - Interactome KW - p53 targets Y1 - 2022 U6 - https://doi.org/10.1007/s00018-022-04345-8 SN - 1420-682X SN - 1420-9071 VL - 79 IS - 6 PB - Springer Nature CY - Basel ER - TY - JOUR A1 - Thayumanasundaram, Savitha A1 - Raman Venkatesan, Thulasinath A1 - Ousset, Aymeric A1 - Van Hollebeke, Kim A1 - Aerts, Luc A1 - Wubbenhorst, Michael A1 - Van den Mooter, Guy T1 - Complementarity of mDSC, DMA, and DRS Techniques in the Study of T-g and Sub-T-g Transitions in Amorphous Solids BT - PVPVA, Indomethacin, and Amorphous Solid Dispersions Based on Indomethacin/PVPVA JF - Molecular pharmaceutics N2 - Recently, glasses, a subset of amorphous solids, have gained attention in various fields, such as polymer chemistry, optical fibers, and pharmaceuticals. One of their characteristic features, the glass transition temperature (T-g) which is absent in 100% crystalline materials, influences several material properties, such as free volume, enthalpy, viscosity, thermodynamic transitions, molecular motions, physical stability, mechanical properties, etc. In addition to T-g, there may be several other temperaturedependent transitions known as sub-T-g transitions (or beta-, gamma-, and delta-relaxations) which are identified by specific analytical techniques. The study of T-g and sub-T-g transitions occurring in amorphous solids has gained much attention because of its importance in understanding molecular kinetics, and it requires the combination of conventional and novel characterization techniques. In the present study, three different analytical techniques [modulated differential scanning calorimetry (mDSC), dynamic mechanical analysis (DMA), and dielectric relaxation spectroscopy (DRS)] were used to perform comprehensive qualitative/quantitative characterization of molecular relaxations, miscibility, and molecular interactions present in an amorphous polymer (PVPVA), a model drug (indomethacin, IND), and IND/PVPVA-based amorphous solid dispersions (ASDs). This is the first ever reported DMA study on PVPVA in its powder form, which avoids the contribution of solvent to the mechanical properties when a selfstanding polymer film is used. A good correlation between the techniques in determining the T-g value of PVPVA, IND, and IND/ PVPVA-based ASDs is established, and the negligible difference (within 10 degrees C) is attributed to the different material properties assessed in each technique. However, the overall T-g behavior, the decrease in T-g with increase in drug loading in ASDs, is universally observed in all the above-mentioned techniques, which reveals their complementarity. DMA and DRS techniques are used to study the different sub-T-g transitions present in PVPVA, amorphous IND, and IND/PVPVA-based ASDs because these transitions are normally too weak or too broad for mDSC to detect. For IND/PVPVA-based ASDs, both techniques show a shift of sub-T-g transitions (or secondary relaxation peaks) toward the high-temperature region from -140 to -45 degrees C. Thus, this paper outlines the usage of different solid-state characterization techniques in understanding the different molecular dynamics present in the polymer, drug, and their interactions in ASDs with the integrated information obtained from individual techniques. KW - amorphous solids KW - PVPVA KW - indomethacin KW - ASDs KW - dynamic mechanical KW - analysis KW - dielectric relaxation spectroscopy KW - sub-T-g relaxations KW - relaxation dynamics Y1 - 2022 U6 - https://doi.org/10.1021/acs.molpharmaceut.2c00123 SN - 1543-8384 SN - 1543-8392 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Sobhkhiz-Miandehi, Sahar A1 - Yamazaki, Yosuke A1 - Arras, Christina A1 - Miyoshi, Yasunobu A1 - Shinagawa, Hiroyuki T1 - Comparison of the tidal signatures in sporadic E and vertical ion convergence rate, using FORMOSAT-3/COSMIC radio occultation observations and GAIA model JF - Earth, planets and space : EPS N2 - Sporadic E or Es is a transient phenomenon where thin layers of enhanced electron density appear in the ionospheric E region (90-120 km altitude). The neutral wind shear caused by atmospheric tides can lead ions to converge vertically at E-region heights and form the Es layer. This research aims to determine the role of atmospheric solar and lunar tides in Es occurrence. For this purpose, radio occultation data of FORMOSAT-3/COSMIC have been used, which provide complete global coverage of Es events. Moreover, GAIA model simulations have been employed to evaluate the vertical ion convergence induced by solar tides. The results show both migrating and non-migrating solar tidal signatures and the semidiurnal migrating lunar tidal signature mainly in low and mid-latitude Es occurrence. The seasonal variation of the migrating solar tidal components of Es is in good agreement with those in the vertical ion convergence derived from GAIA at higher altitudes. Furthermore, some non-migrating components of solar tides, including semidiurnal westward wavenumbers 1 and 3 and diurnal eastward wavenumbers 2 and 3, also significantly affect the Es occurrence rate. KW - Sporadic E KW - Es KW - wind shear KW - solar tide KW - lunar tide KW - GAIA KW - radio occultation Y1 - 2022 U6 - https://doi.org/10.1186/s40623-022-01637-y SN - 1880-5981 VL - 74 IS - 1 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Huang, Yizhen A1 - Richter, Eric A1 - Kleickmann, Thilo A1 - Richter, Dirk T1 - Comparing video and virtual reality as tools for fostering interest and self-efficacy in classroom management BT - results of a pre-registered experiment JF - British journal of educational technology / British Educational Communications and Technology Agency N2 - Video is a widely used medium in teacher training for situating student teachers in classroom scenarios. Although the emerging technology of virtual reality (VR) provides similar, and arguably more powerful, capabilities for immersing teachers in lifelike situations, its benefits and risks relative to video formats have received little attention in the research to date. The current study used a randomized pretest-posttest experimental design to examine the influence of a video- versus VR-based task on changing situational interest and self-efficacy in classroom management. Results from 49 student teachers revealed that the VR simulation led to higher increments in self-reported triggered interest and self-efficacy in classroom management, but also invoked higher extraneous cognitive load than a video viewing task. We discussed the implications of these results for pre-service teacher education and the design of VR environments for professional training purposes. Practitioner notes What is already known about this topic Video is a popular teacher training medium given its ability to display classroom situations. Virtual reality (VR) also immerses users in lifelike situations and has gained popularity in recent years. Situational interest and self-efficacy in classroom management is vital for student teachers' professional development. What this paper adds VR outperforms video in promoting student teachers' triggered interest in classroom management. Student teachers felt more efficacious in classroom management after participating in VR. VR also invoked higher extraneous cognitive load than the video. Implications for practice and/or policy VR provides an authentic teacher training environment for classroom management. The design of the VR training environment needs to ensure a low extraneous cognitive load. KW - cognitive load KW - immersive media KW - pre-service teacher KW - professional KW - training KW - simulations KW - student teacher KW - teacher education Y1 - 2022 U6 - https://doi.org/10.1111/bjet.13254 SN - 0007-1013 SN - 1467-8535 VL - 54 IS - 2 SP - 467 EP - 488 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Braun, Jean T1 - Comparing the transport-limited and ξ-q models for sediment transport JF - Earth surface dynamics N2 - Here I present a comparison between two of the most widely used reduced-complexity models for the representation of sediment transport and deposition processes, namely the transport-limited (or TL) model and the under-capacity (or xi-q) model more recently developed by Davy and Lague (2009). Using both models, I investigate the behavior of a sedimentary continental system of length L fed by a fixed sedimentary flux from a catchment of size A(0) in a nearby active orogen through which sediments transit to a fixed base level representing a large river, a lake or an ocean. This comparison shows that the two models share the same steady-state solution, for which I derive a simple 1D analytical expression that reproduces the major features of such sedimentary systems: a steep fan that connects to a shallower alluvial plain. The resulting fan geometry obeys basic observational constraints on fan size and slope with respect to the upstream drainage area, A(0). The solution is strongly dependent on the size of the system, L, in comparison to a distance L-0, which is determined by the size of A(0), and gives rise to two fundamentally different types of sedimentary systems: a constrained system where L < L-0 and open systems where L > L-0. I derive simple expressions that show the dependence of the system response time on the system characteristics, such as its length, the size of the upstream catchment area, the amplitude of the incoming sedimentary flux and the respective rate parameters (diffusivity or erodibility) for each of the two models. I show that the xi-q model predicts longer response times. I demonstrate that although the manner in which signals propagates through the sedimentary system differs greatly between the two models, they both predict that perturbations that last longer than the response time of the system can be recorded in the stratigraphy of the sedimentary system and in particular of the fan. Interestingly, the xi-q model predicts that all perturbations in the incoming sedimentary flux will be transmitted through the system, whereas the TL model predicts that rapid perturbations cannot. I finally discuss why and under which conditions these differences are important and propose observational ways to determine which of the two models is most appropriate to represent natural systems. Y1 - 2022 U6 - https://doi.org/10.5194/esurf-10-301-2022 SN - 2196-6311 SN - 2196-632X VL - 10 IS - 2 SP - 301 EP - 327 PB - Copernicus CY - Göttingen ER -