500 Naturwissenschaften und Mathematik
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The ability to reflect is considered an essential element of Education for Sustainable Development (ESD) and a key competence for learners and educators in ESD (UNECE Strategy for ESD, 2012). In contrast to its high importance, little is known about how reflective thinking can be identified, influenced or increased in the classroom. Therefore, the objective of this study is to address this need by developing an empirical multi-stage model designed to help educators diagnose different levels of reflective thinking and to identify factors that influence students’ reflective thinking about sustainability. Based on a 4–8-week project with grade 10 and 11 students studying sustainability, reflective thinking performance using weblogs as reflective journals was analysed. In addition, qualitative semi-structured interviews were conducted with the teachers to comprehend the learning environment and the personal value they assigned to ESD in their geography class. To determine the levels of reflective thinking achieved by the students, the study built on the work of Dewey (1933) and pre-existing multi-stage models of reflective thinking (Bain, Ballantyne, & Packer, 1999; Chen, Wei, Wu, & Uden, 2009). Using a qualitative, iterative data analysis, the study adapted the stage models to be applicable in ESD and found great differences in the students’ reflection levels. Furthermore, the study identified eight factors that influence students’ reflective thinking about sustainability. The outcomes of this study may be valuable for educators in high school and higher education, who seek to diagnose their students’ reflective thinking performance and facilitate reflection about sustainability.
Sustained glacier melt in the Himalayas has gradually spawned more than 5,000 glacier lakes that are dammed by potentially unstable moraines. When such dams break, glacier lake outburst floods (GLOFs) can cause catastrophic societal and geomorphic impacts. We present a robust probabilistic estimate of average GLOFs return periods in the Himalayan region, drawing on 5.4 billion simulations. We find that the 100-y outburst flood has an average volume of 33.5(+3.7)/(-3.7) x 10(6) m(3) (posterior mean and 95% highest density interval [HDI]) with a peak discharge of 15,600(+2.000)/(-1,800) m(3).S-1. Our estimated GLOF hazard is tied to the rate of historic lake outbursts and the number of present lakes, which both are highest in the Eastern Himalayas. There, the estimated 100-y GLOF discharge (similar to 14,500 m(3).s(-1)) is more than 3 times that of the adjacent Nyainqentanglha Mountains, and at least an order of magnitude higher than in the Hindu Kush, Karakoram, and Western Himalayas. The GLOF hazard may increase in these regions that currently have large glaciers, but few lakes, if future projected ice loss generates more unstable moraine-dammed lakes than we recognize today. Flood peaks from GLOFs mostly attenuate within Himalayan headwaters, but can rival monsoon-fed discharges in major rivers hundreds to thousands of kilometers downstream. Projections of future hazard from meteorological floods need to account for the extreme runoffs during lake outbursts, given the increasing trends in population, infrastructure, and hydropower projects in Himalayan headwaters.
High-precision observations of the present-day geomagnetic field by ground-based observatories and satellites provide unprecedented conditions for unveiling the dynamics of the Earth’s core. Combining geomagnetic observations with dynamo simulations in a data assimilation (DA) framework allows the reconstruction of past and present states of the internal core dynamics. The essential information that couples the internal state to the observations is provided by the statistical correlations from a numerical dynamo model in the form of a model covariance matrix. Here we test a sequential DA framework, working through a succession of forecast and analysis steps, that extracts the correlations from an ensemble of dynamo models. The primary correlations couple variables of the same azimuthal wave number, reflecting the predominant axial symmetry of the magnetic field. Synthetic tests show that the scheme becomes unstable when confronted with high-precision geomagnetic observations. Our study has identified spurious secondary correlations as the origin of the problem. Keeping only the primary correlations by localizing the covariance matrix with respect to the azimuthal wave number suffices to stabilize the assimilation. While the first analysis step is fundamental in constraining the large-scale interior state, further assimilation steps refine the smaller and more dynamical scales. This refinement turns out to be critical for long-term geomagnetic predictions. Increasing the assimilation steps from one to 18 roughly doubles the prediction horizon for the dipole from about tree to six centuries, and from 30 to about 60 yr for smaller observable scales. This improvement is also reflected on the predictability of surface intensity features such as the South Atlantic Anomaly. Intensity prediction errors are decreased roughly by a half when assimilating long observation sequences.
Molecular identification of late and terminal Pleistocene Equus ovodovi from northeastern China
(2019)
The extant diversity of horses (family Equidae) represents a small fraction of that occurring over their evolutionary history. One such lost lineage is the subgenus Sussemionus, which is thought to have become extinct during the Middle Pleistocene. However, recent molecular studies and morphological analysis have revealed that one of their representatives, E. ovodovi, did exist in Siberia during the Late Pleistocene. Fossil materials of E. ovodovi have thus far only been found in Russia. In this study, we extracted DNA from three equid fossil specimens excavated from northeastern China dated at 12,770-12,596, 29,525-28,887 and 40,201-38,848 cal. yBP, respectively, and retrieved three near-complete mitochondrial genomes from the specimens. Phylogenetic analyses cluster the Chinese haplotypes together with previously published Russian E. ovodovi, strongly supporting the assignment of these samples to this taxon. The molecular identification of E. ovodovi in northeastern China extends the known geographical range of this fossil species by several thousand kilometers to the east. The estimated coalescence time of all E. ovodovi haplotypes is approximately 199 Kya, with the Chinese haplotypes coalescing approximately 130 Kya. With a radiocarbon age of 12,770-12,596 cal. yBP, the youngest sample in this study represents the first E. ovodovi sample dating to the terminal Pleistocene, moving the extinction date of this species forwards considerably compared to previously documented fossils. Overall, comparison of our three mitochondrial genomes with the two published ones suggests a genetic diversity similar to several extant species of the genus Equus.
Role of GDF15 in active lifestyle induced metabolic adaptations and acute exercise response in mice
(2019)
Physical activity is an important contributor to muscle adaptation and metabolic health. Growth differentiation factor 15 (GDF15) is established as cellular and nutritional stress-induced cytokine but its physiological role in response to active lifestyle or acute exercise is unknown. Here, we investigated the metabolic phenotype and circulating GDF15 levels in lean and obese male C57BI/6J mice with long-term voluntary wheel running (VWR) intervention. Additionally, treadmill running capacity and exercise-induced muscle gene expression was examined in GDF15-ablated mice. Active lifestyle mimic via VWR improved treadmill running performance and, in obese mice, also metabolic phenotype. The post-exercise induction of skeletal muscle transcriptional stress markers was reduced by VWR. Skeletal muscle GDF15 gene expression was very low and only transiently increased post-exercise in sedentary but not in active mice. Plasma GDF15 levels were only marginally affected by chronic or acute exercise. In obese mice, VWR reduced GDF15 gene expression in different tissues but did not reverse elevated plasma GDF15. Genetic ablation of GDF15 had no effect on exercise performance but augmented the post exercise expression of transcriptional exercise stress markers (Atf3, Atf6, and Xbp1s) in skeletal muscle. We conclude that skeletal muscle does not contribute to circulating GDF15 in mice, but muscle GDF15 might play a protective role in the exercise stress response.
Oscillatory systems under weak coupling can be described by the Kuramoto model of phase oscillators. Kuramoto phase oscillators have diverse applications ranging from phenomena such as communication between neurons and collective influences of political opinions, to engineered systems such as Josephson Junctions and synchronized electric power grids. This thesis includes the author's contribution to the theoretical framework of coupled Kuramoto oscillators and to the understanding of non-trivial N-body dynamical systems via their reduced mean-field dynamics.
The main content of this thesis is composed of four parts. First, a partially integrable theory of globally coupled identical Kuramoto oscillators is extended to include pure higher-mode coupling. The extended theory is then applied to a non-trivial higher-mode coupled model, which has been found to exhibit asymmetric clustering. Using the developed theory, we could predict a number of features of the asymmetric clustering with only information of the initial state provided.
The second part consists of an iterated discrete-map approach to simulate phase dynamics. The proposed map --- a Moebius map --- not only provides fast computation of phase synchronization, it also precisely reflects the underlying group structure of the dynamics. We then compare the iterated-map dynamics and various analogous continuous-time dynamics. We are able to replicate known phenomena such as the synchronization transition of the Kuramoto-Sakaguchi model of oscillators with distributed natural frequencies, and chimera states for identical oscillators under non-local coupling.
The third part entails a particular model of repulsively coupled identical Kuramoto-Sakaguchi oscillators under common random forcing, which can be shown to be partially integrable. Via both numerical simulations and theoretical analysis, we determine that such a model cannot exhibit stationary multi-cluster states, contrary to the numerical findings in previous literature. Through further investigation, we find that the multi-clustering states reported previously occur due to the accumulation of discretization errors inherent in the integration algorithms, which introduce higher-mode couplings into the model. As a result, the partial integrability condition is violated.
Lastly, we derive the microscopic cross-correlation of globally coupled non-identical Kuramoto oscillators under common fluctuating forcing. The effect of correlation arises naturally in finite populations, due to the non-trivial fluctuations of the meanfield. In an idealized model, we approximate the finite-sized fluctuation by a Gaussian white noise. The analytical approximation qualitatively matches the measurements in numerical experiments, however, due to other periodic components inherent in the fluctuations of the mean-field there still exist significant inconsistencies.
Background There is scant information on the breastmilk vitamin A (BMVA) concentration of lactating women in developing countries, partly due to lack of methods applicable in-field. Objective To assess BMVA concentrations of samples collected from lactating women of children aged 6-23 months, in Mecha district, Ethiopia. Subjects/methods Data on socio-demographic and anthropometric characteristics were collected from randomly selected lactating women (n = 104). Breast milk samples were collected and vitamin A concentrations were analyzed using HPLC and iCheck FLUORO then the two measurements were compared. Results The prevalence of underweight (BMI < 18.5 kg/m(2)) among lactating women was 17%. Seventy six percent of the BMVA values were < 1.05 mu mol/l and 81% were < 8 mu g/g fat. The mean BMVA concentration accounted to 41% of the estimated average value for mothers in developing countries. The BMVA values from HPLC and iCheck were correlated (r = 0.59, p = < 0.001), but it was not strong. Conclusions The result indicates the low vitamin A status of the lactating women and their children. It further indicates that intake assessments should not use average BMVA composition. The possibility of using iCheck for monitoring interventions designed to improve vitamin A status of lactating women with low BMVA requires further investigation.
Purpose of review In addition to the currently available lysosomotropic drugs and autophagy whole-body knockout mouse models, we provide alternative methods that enable the modulation and detection of autophagic flux in vivo, discussing advantages and disadvantages of each method. Recent findings With the autophagosome-lysosome fusion inhibitor colchicine in skeletal muscle and temporal downregulation of autophagy using a novel Autophagy related 5-short hairpin RNA (Atg5-shRNA) mouse model we mention two models that directly modulate autophagy flux in vivo. Furthermore, methods to quantify autophagy flux, such as mitophagy transgenic reporters, in situ immunofluorescent staining and multispectral imaging flow cytometry, in mature skeletal muscle and cells are addressed. To achieve clinical benefit, less toxic, temporary and cell-type-specific modulation of autophagy should be pursued further. A temporary knockdown as described for the Atg5-shRNA mice could provide a first insight into possible implications of autophagy inhibition. However, it is also important to take a closer look into the methods to evaluate autophagy after harvesting the tissue. In particular caution is required when experimental conditions can influence the final measurement and this should be pretested carefully.
Britholite group minerals (REE,Ca)(5)[(Si,P)O-4](3)(OH,F) are widespread rare-earth minerals in alkaline rocks and their associated metasomatic zones, where they usually are minor accessory phases. An exception is the REE deposit Rodeo de los Molles, Central Argentina, where fluorbritholite-(Ce) (FBri) is the main carrier of REE and is closely intergrown with fluorapatite (FAp). These minerals reach an abundance of locally up to 75 modal% (FBri) and 20 modal% (FAp) in the vein mineralizations. The Rodeo de los Molles deposit is hosted by a fenitized monzogranite of the Middle Devonian Las Chacras-Potrerillos batholith. The REE mineralization consists of fluorbritholite-(Ce), britholite-(Ce), fluorapatite, allanite-(Ce), and REE fluorcarbonates, and is associated with hydrothermal fluorite, quartz, albite, zircon, and titanite. The REE assemblage takes two forms: irregular patchy shaped REE-rich composites and discrete cross-cutting veins. The irregular composites are more common, but here fluorbritholite-(Ce) is mostly replaced by REE carbonates. The vein mineralization has more abundant and better-preserved britholite phases. The majority of britholite grains at Rodeo de los Molles are hydrothermally altered, and alteration is strongly enhanced by metamictization, which is indicated by darkening of the mineral, loss of birefringence, porosity, and volume changes leading to polygonal cracks in and around altered grains. A detailed electron microprobe study of apatite-britholite minerals from Rodeo de los Molles revealed compositional variations in fluorapatite and fluorbritholite-(Ce) consistent with the coupled substitution of REE3+ + Si4+ = Ca2+ + P5+ and a compositional gap of similar to 4 apfu between the two phases, which we interpret as a miscibility gap. Micrometer-scale intergrowths of fluorapatite in fluorbritholite-(Ce) minerals and vice versa are chemically characterized here for the first time and interpreted as exsolution textures that formed during cooling below the proposed solvus.
In an overt visual priming experiment, we investigate the role of orthography in native (L1) and non-native (L2) processing of German morphologically complex words. We compare priming effects for inflected and derived morphologically related prime-target pairs versus otherwise matched, purely orthographically related pairs. The results show morphological priming effects in both the L1 and L2 group, with no significant difference between inflection and derivation. However, L2 speakers, but not L1 speakers, also showed significant priming for orthographically related pairs. Our results support the claim that L2 speakers focus more on surface-level information such as orthography during visual word recognition. This can cause orthographic priming effects in morphologically related prime-target pairs, which may conceal L1-L2 differences in morphological processing.