Cognitive load and science text comprehension: Effects of drawing and mentally imagining text content

One hundred and eleven 10th graders read an expository science text on the dipole character of water molecules (ca. 1600 words). Reading instruction was varied according to a 2 × 2 experimental design with factors ‘drawing pictures of text content on paper’ (yes, no) and ‘mentally imagining text content while reading’ (yes, no). The results indicate that drawing pictures, mediated through increased cognitive load, decreased text comprehension and, thus, learning (d = −0.37), whereas mental imagery, although decreasing cognitive load, increased comprehension only when students did not have to draw pictures simultaneously (d = 0.72). No evidence was found that the effects were moderated by domain-specific prior knowledge, verbal ability, or spatial ability. The results are in line with cognitive theories of multimedia learning, self-regulated learning, and mental imagery as well as conceptions of science learning that focus on promoting mental model construction by actively visualizing the content to be learned. Constructing mental images seems to reduce cognitive load and to increase comprehension and learning outcome when the mental visualization processes are not disturbed by externally drawing pictures on paper, whereas drawing pictures seems to increase cognitive load resulting in reduced comprehension and learning outcome.     

Potential of low bandwidth active suspension control with continuously variable damper

In this paper, the performance potential of a new hardware combination for active suspension systems is presented. It consists of a low bandwidth actuator and a continuously variable damper, a setup that is shown to be competitive to high bandwidth active suspension systems especially if energy, cost and implementability aspects are taken into account. This is achieved by an iterative optimization procedure for the damping ratio and the weights of time-invariant LQR controllers for active quarter-car models. The results of the procedure are obtained by simulations employing a road disturbance model that is validated using measurements of a real highway profile. The achievable performance of the new hardware combination is compared to passive and high bandwidth active suspension systems by means of carpet plots. Based on the comparison results, it is shown that ride comfort can be significantly increased while satisfying given constraints for ride safety (maximum tire deflections) and suspension travel.     

Fast and intuitive generation of geometric shape transitions

We describe a novel method for continuously transforming two triangulated models of arbitrary topology into each other. Equal global topology for both objects is assumed. However, extensions for genus changes during metamorphosis are provided. The proposed method addresses the major challenge in 3D metamorphosis, namely, specifying the morphing process intuitively with minimal user interaction and sufficient detail. Corresponding regions and point features are interactively identified. These regions are parametrized automatically and consistently, providing a basis for smooth interpolation. Suitable 3D interaction techniques offer a simple and intuitive control over the whole morphing process.     

Validation of the collection 5 MODIS FPAR product in a heterogeneous agricultural landscape in arid Uzbekistan using multitemporal RapidEye imagery

The fraction of photosynthetically active radiation (FPAR) absorbed by a vegetation canopy is an important variable for global vegetation modelling and is operationally available from data of the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) satellite sensor starting from the year 2000. Product validation is ongoing and important for constant product improvement, but few studies have investigated the specific accuracy of MODIS FPAR using in situ measurements and none have focused on agricultural areas. This study therefore presents a validation of the collection 5 MODIS FPAR product in a heterogeneous agricultural landscape in western Uzbekistan. High-resolution FPAR maps were compiled via linear regression between in situ FPAR measurements and the RapidEye normalized difference vegetation index (NDVI) for the 2009 season. The data were aggregated to the MODIS scale for comparison. Data on the percentage cover of agricultural crops per MODIS pixel allowed investigation of the impact of spatial heterogeneity on MODIS FPAR accuracy. Overall, the collection 5 MODIS FPAR overestimated RapidEye FPAR between approximately 6% and 15%. MODIS quality flags, the underlying biome classification and spatial heterogeneity were investigated as potential sources of error. MODIS data quality was very good in all cases. A comparison of the MODIS land-cover product with high-resolution land-use classification revealed a significant misclassification by MODIS. Yet, we found that the overestimation of MODIS FPAR is independent of classification accuracy. The results indicate that the amount of background information, present even in the most homogeneous pixels (～70% crop cover), is most likely the reason for the overestimation. The behaviour of pure pixels could not be investigated due to a lack of appropriate pixels.     

Stability of solid electrolyte based thick-film CO2 sensors

Long-term stability is one of the major issues in the ongoing development of solid electrolyte based, screen-printed potentiometric CO₂ sensors. Though improvements of the sensor have been reported by several research groups, mostly due to changes in material combinations, little is referred to the influence of basic technological aspects in relation to the observable degradation effects. In view of this aspect potentiometric thick-film CO₂ sensors based on the electrochemical cell: Au, O₂, CO₂ |Ma₂CO₃-MeCO₃ (Au)||Na-β/β′′-Al₂O₃||Na₂Si₂O₅ SiO₂ (Au)|O₂, (CO₂), Au {Ma = Na or Li; Me = Ba or Ca} were investigated regarding the long-term stability at improved operating conditions. As previous works at the IKTS in Dresden have shown that the microstructure of the Na-beta-Aluminate (NBA) and the sensor preheating conditions have considerable influence on the stability, now different carbonate materials where evaluated regarding the influence on stability at improved operating conditions. So far, satisfying performance over more than 2000 h was demonstrated independent of the carbonate material used in the miniaturized CO₂ sensor.     

Analysis of atmospheric sesquiterpenes: sampling losses and mitigation of ozone interferences

Atmospheric standards containing parts-per-billion levels of 14 semivolatile hydrocarbon compounds, including eight sesquiterpenes (SQTs) (longipinene, alpha-copaene, isolongifolene, alpha-cedrene, trans-caryophyllene, aromadendrene, alpha-humulene, delta-cadinene), two oxidized sesquiterpenoids (cisnerolidol, trans-nerolidol), one biogenic ketone (geranylacetone) and three aromatic compounds (1,3,5-triisopropylbenzene, diphenylmethane, nonylbenzene), were collected onto four solid adsorbent materials at increasing ozone mixing ratios (0-100 ppbv 03) for analysis by thermodesorption-gas chromatography. Substantial sampling losses of up to >90% were found for the most reactive SQT, even at the lowest ozone level investigated of 20 ppbv. Loss rates from the ozone-SQT reaction were used to derive estimates of gas-phase ozone reaction rate constants for longipinene, alpha-copaene, isolongifolene, geranylacetone, aromadendrene, delta-cadinene, cis-nerolidol, and transnerolidol. Three different ozone mitigation techniques were investigated to prevent these sampling losses. These strategies included (a) placing glass fiber filters impregnated with sodium thiosulfate (Na2S2O3) into the sampling line, (b) titration of ozone in the sampling stream with nitric oxide (NO), and (c) catalytically removing ozone with a commercially available manganese dioxide (MnO2) catalyst. All three techniques reduced ozone-mixing ratios from 100 ppbv to <0.6 ppbv at sampling flow rates of 1 L min(-1). When the Na2S2O3 filters and the NO-titration techniques were applied, SQT loss rates decreased from 25-60% to 0-5% for most SQT compounds and from >90% to approximately 10-50% for the two most reactive compounds at ozone mixing ratios of up to 100 ppbv. The commercial manganese dioxide scrubber, however, caused complete analyte losses (>98%) even at 0 ppbv ozone. These results underline the need and present applicable techniques for removal of ozone in air samples for SQT analysis by solid adsorption techniques.     

Deep UV laser-induced fluorescence detection of unlabeled drugs and proteins in microchip electrophoresis

Deep UV fluorescence detection at 266-nm excitation wavelength has been realized for sensitive detection in microchip electrophoresis. For this purpose, an epifluorescence setup was developed enabling the coupling of a deep UV laser into a commercial fluorescence microscope. Deep UV laser excitation utilizing a frequency quadrupled pulsed laser operating at 266 nm shows an impressive performance for native fluorescence detection of various compounds in fused-silica microfluidic devices. Aromatic low molecular weight compounds such as serotonin, propranolol, a diol, and tryptophan could be detected at low-micromolar concentrations. Deep UV fluorescence detection was also successfully employed for the detection of unlabeled basic proteins. For this purpose, fused-silica chips dynamically coated with hydroxypropylmethyl cellulose were employed to suppress analyte adsorption. Utilizing fused-silica chips permanently coated with poly(vinyl alcohol), it was also possible to separate and detect egg white chicken proteins. These data show that deep UV fluorescence detection significantly widens the application range of fluorescence detection in chip-based analysis techniques.     

Importance of cell wall mannoproteins for septum formation in Saccharomyces cerevisiae

The mannosyltransferase mutants mnn9 and mnn10 were isolated in a genetic screen for septation defects in Saccharomyces cerevisiae. Ultrastructural examination of mutant cell walls revealed markedly thin septal structures and occasional failure to construct trilaminar septa, which then led to the formation of bulky default septa at the bud neck. In the absence of a functional septation apparatus, mnn10 mutants are unable to complete cytokinesis and die as cell chains with incompletely separated cytoplasms, indicating that mannosylation defects impair the ability to form remedial septa. We could not detect N-linked glycosylation of the beta(1,3)glucan synthase Fks1p and mnn10 defects do not change the molecular weight or abundance of the protein. We discuss a model explaining the pleiotropic effects of impaired N-linked protein glycosylation on septation in S. cerevisiae.