503 research outputs found
Complexity in Education for Sustainable Consumption—An Educational Data Mining Approach using Mysteries
Systems thinking is one of the skills necessary for sustainable behavior, especially regarding sustainable consumption. Students are faced with complexity and uncertainty while taking part in it and other daily life aspects. There is a need to foster their competence in this field. From a classroom point of view, the mystery method is an example for implementing education for sustainable consumption and working with complex and uncertain content. With the mystery method students construct an influence diagram, which consists of concepts and requires several skills, especially in decision-making. Using these diagrams as a form of assessment is desirable but also very difficult, because of the mentioned complexity and uncertainty that is part of the task itself. The study presented here tackles this problem by creating an expert based reference diagram that has been constructed with the help of educational data mining. The result shows that it is possible to derive such a reference even if parts remain ambiguous due to the inherent complexity. The reference may now be used to assess students’ systems thinking abilities, which will be undertaken in future research. Beside this, the reference can be used as a reflective tool in lessons, so students can compare their own content knowledge and discuss differences to the experts’ reference
The Mystery Method Reconsidered—A Tool for Assessing Systems Thinking in Education for Sustainable Development
Influence diagrams, derived from the mystery method as its learning output, represent
an externalization of systems thinking and are, therefore, valid to research; so far they have not been
conceptualized in the research literature for teaching systems thinking in education for sustainable
development. In this study, 31 of those diagrams are confronted with (1) three different expert
references, in (2) two different ways, by (3) three different scoring systems to determine which
evaluation option is both valid and easy to implement. As a benchmark, the diagrams’ diameters
are used, which allows statements about the quality of the maps/diagrams in general. The results
show that, depending on the combination of variables that play a role in the evaluation (1, 2, 3),
the quality of the influence diagram becomes measurable. However, strong differences appear in
the various evaluation schemes, which can be explained by each variable’s peculiarities. Overall,
the tested methodology is effective, but will need to be sharpened in the future. The results also offer
starting points for future research to further deepen the path taken here
Sialic Acid Utilisation and Synthesis in the Neonatal Rat Revisited
Background: Milk is the sole source of nutrients for neonatal mammals and is generally considered to have co-evolved with the developmental needs of the suckling newborn. One evolutionary conserved constituent of milk and present on many glycoconjugates is sialic acid. The brain and colon are major sites of sialic acid display and together with the liver also of synthesis. Methodology/Principal Findings: In this study we examined in rats the relationship between the sialic acid content of milk and the uptake, utilization and synthesis of sialic acid in suckling pups. In rat milk sialic acid was found primarily as 39sialyllactose and at highest levels between 3 and 10 days postpartum and that decreased towards weaning. In the liver of suckling pups sialic acid synthesis paralleled the increase in milk sialic acid reaching and keeping maximum activity from postnatal day 5 onwards. In the colon, gene expression profiles suggested that a switch from sialic acid uptake and catabolism towards sialic acid synthesis and utilization occurred that mirrored the change of sialic acid in milk from high to low expression. In brain sialic acid related gene expression profiles did not change to any great extent during the suckling period. Conclusions/Significance: Our results support the views that (i) when milk sialic acid levels are high, in the colon this sialic acid is catabolized to GlcNAc that in turn may be used as such or used as substrate for sialic acid synthesis and (ii) when milk sialic acid levels are low the endogenous sialic acid synthetic machinery in colon is activated
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The ipsilesional attention bias in right hemisphere stroke patients as revealed by a realistic visual search task: neuroanatomical correlates and functional relevance
Objective: Right hemisphere stroke may cause an ipsilesional attention bias and left hemispatial neglect. Computerized time-limited tasks are more sensitive than conventional paper-pencil tests in detecting these spatial attention deficits. However, their frequency in the acute stage of stroke, the neuroanatomical basis and functional relevance for patients’ everyday life are unclear.
Method: A realistic visual search task is introduced, in which eye movements are recorded while the patient searches for paperclips among different everyday objects on a computer display. The “Desk task” performance of 34 acute right hemisphere stroke patients was compared to established paper-pencil tests for neglect and the Posner reaction time task, and finally correlated to structural brain lesions.
Results: Most of the patients, even those without clinical neglect signs and with normal paper-pencil test performance, exhibited a clear ipsilesional attention bias in the Desk task. This bias was highly correlated to the left-right asymmetry in the Posner task and to neglect-related functional impairment scores. Lesion-symptom mapping revealed task-specific differences: deficits in the Desk task were associated with lesions of the superior temporal gyrus, contralesional unawareness in the Posner task with ventral frontal cortex lesions and paper-pencil cancellation bias with damage to the inferior parietal lobe. Neglect behavior was further associated with distinct fronto-parietal white matter tract disconnections (ILF, SLF, Arcuate).
Conclusions: Results from the novel Desk task indicate a functional relevance of spatial attention deficits in right brain damaged patients, even if they are “subclinical”. This should be considered especially in patients without obvious clinical neglect signs.urology and Psychology, University of Lübeck.This work was supported by the Deutsche Forschungsgemeinschaft(Grants MA5332/1-1 and MA5332/3-1 to Björn Machner) and the Well-come Trust (Grants 091806 and 106926 to Paul M. Bays)
Wave curves: Simulating Lagrangian water waves on dynamically deforming surfaces
We propose a method to enhance the visual detail of a water surface simulation. Our method works as a post-processing step which takes a simulation as input and increases its apparent resolution by simulating many detailed Lagrangian water waves on top of it. We extend linear water wave theory to work in non-planar domains which deform over time, and we discretize the theory using Lagrangian wave packets attached to spline curves. The method is numerically stable and trivially parallelizable, and it produces high frequency ripples with dispersive wave-like behaviors customized to the underlying fluid simulation
Steady azimuthal flow field induced by a rotating sphere near a rigid disk or inside a gap between two coaxially positioned rigid disks
Geometric confinements play an important role in many physical and biological
processes and significantly affect the rheology and behavior of colloidal
suspensions at low Reynolds numbers. On the basis of the linear Stokes
equations, we investigate theoretically and computationally the viscous
azimuthal flow induced by the slow rotation of a small spherical particle
located in the vicinity of a rigid no-slip disk or inside a gap between two
coaxially positioned rigid no-slip disks of the same radius. We formulate the
solution of the hydrodynamic problem as a mixed-boundary-value problem in the
whole fluid domain, which we subsequently transform into a system of dual
integral equations. Near a stationary disk, we show that the resulting integral
equation can be reduced into an elementary Abel integral equation that admits a
unique analytical solution. Between two coaxially positioned stationary disks,
we demonstrate that the flow problem can be transformed into a system of two
Fredholm integral equations of the first kind. The latter are solved by means
of numerical approaches. Using our solution, we further investigate the effect
of the disks on the slow rotational motion of a colloidal particle and provide
expressions of the hydrodynamic mobility as a function of the system geometry.
We compare our results with corresponding finite-element simulations and
observe very good agreement.Comment: 13 pages, 7 figure
Towards an analytical description of active microswimmers in clean and in surfactant-covered drops
Geometric confinements are frequently encountered in the biological world and
strongly affect the stability, topology, and transport properties of active
suspensions in viscous flow. Based on a far-field analytical model, the
low-Reynolds-number locomotion of a self-propelled microswimmer moving inside a
clean viscous drop or a drop covered with a homogeneously distributed
surfactant, is theoretically examined. The interfacial viscous stresses induced
by the surfactant are described by the well-established Boussinesq-Scriven
constitutive rheological model. Moreover, the active agent is represented by a
force dipole and the resulting fluid-mediated hydrodynamic couplings between
the swimmer and the confining drop are investigated. We find that the presence
of the surfactant significantly alters the dynamics of the encapsulated swimmer
by enhancing its reorientation. Exact solutions for the velocity images for the
Stokeslet and dipolar flow singularities inside the drop are introduced and
expressed in terms of infinite series of harmonic components. Our results offer
useful insights into guiding principles for the control of confined active
matter systems and support the objective of utilizing synthetic microswimmers
to drive drops for targeted drug delivery applications.Comment: 19 pages, 7 figures. Regular article contributed to the Topical Issue
of the European Physical Journal E entitled "Physics of Motile Active Matter"
edited by Gerhard Gompper, Clemens Bechinger, Holger Stark, and Roland G.
Winkle
Far‐Ranging Impact of Mountain Waves Excited Over Greenland on Stratospheric Dehydration and Rehydration
In situ observations of reduced stratospheric water vapor combined with those of ice particle
formation are rarely conducted. On the one hand, they are essential to broaden our knowledge about the
formation of polar stratospheric clouds (PSCs). On the other hand, the observed proles allow the
comparison with global circulation models
A quantitative analysis of stratospheric HCl, HNO3, and O3 in the tropopause region near the subtropical jet
The effects of chemical two-way mixing on the Extratropical Transition Layer (ExTL) near the
subtropical jet are investigated by stratospheric tracer-tracer correlations. To this end, in situ measurements
were performed west of Africa (25–32◦N) during the Transport and Composition of the Upper Troposphere
Lower Stratosphere (UTLS)/Earth System Model Validation (TACTS/ESMVal) mission in August/September
2012. The Atmospheric chemical Ionization Mass Spectrometer sampling HCl and HNO3 was for the first
time deployed on the new German High Altitude and Long range research aircraft (HALO). Measurements
of O3, CO, European Centre for Medium-Range Weather Forecasts (ECMWF) analysis, and the tight
correlation of the unambiguous tracer HCl to O3 and HNO3 in the lower stratosphere were used to quantify
the stratospheric content of these species in the ExTL. With increasing distance from the tropopause, the
stratospheric content increased from 10% to 100% with differing profiles for HNO3 and O3. Tropospheric
fractions of 20% HNO3 and 40% O3 were detected up to a distance of 30 K above the tropopause
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