Entwicklung und Skalierung eines Tests zur Erfassung des Verständnisses multipler Dokumente von Studierenden

Das Verständnis multipler Dokumente (Multiple Document Comprehension, MDC) wird als Fähigkeit verstanden, aus verschiedenen Informationsquellen eine integrierte Repräsentation eines inhaltlichen Gegenstandsbereichs zu konstruieren. Als solche ist sie sowohl für die erfolgreiche Bewältigung eines Studiums als auch für gesellschaftliche Partizipation eine wichtige Kompetenz. Bislang gibt es jedoch kein etabliertes Diagnostikum in diesem Bereich. Um diese Lücke zu schließen, wurde ein Test entwickelt, der vier zentrale kognitive Anforderungen von MDC abdeckt und auf Basis der Daten von 310 Studierenden sozial- und geisteswissenschaftlicher Fächer überprüft wurde. Die im MDC-Test gemessene Kompetenz erwies sich als eindimensional. Der MDC-Testwert wies theoriekonforme Zusammenhänge mit der Abiturnote, dem Studienabschnitt und der Leistung in einer Essay-Aufgabe auf. Insgesamt liefern die Ergebnisse empirische Belege dafür, dass der Testwert aus dem MDC-Test die fächerübergreifende Fähigkeit von Studierenden wiedergibt, multiple Dokumente zu verstehen. (DIPF/Orig.)Multiple document comprehension (MDC) is defined as the ability to construct an integrated representation based on different sources of information on a particular topic. It is an important competence for both the successful accomplishment of university studies and participation in societal discussions. Yet, there is no established assessment instrument for MDC. Therefore, we developed a test covering four theory-based cognitive requirements of MDC. Based on the data of 310 university students of social sciences and humanities, the MDC test proved to be a unidimensional measure. Furthermore, the test score was related to the final school exam grade, the study level (bachelor / master), and the performance in an essay task. The empirical results suggest that the score of the MDC test can be interpreted as the generic competence of university students to understand multiple documents. (DIPF/Orig.

Contrast-Enhanced Magnetic Resonance Angiography Using a Novel Elastin-Specific Molecular Probe in an Experimental Animal Model

Objectives. The aim of this study was to test the potential of a new elastin-specific molecular agent for the performance of contrast-enhanced first-pass and 3D magnetic resonance angiography (MRA), compared to a clinically used extravascular contrast agent (gadobutrol) and based on clinical MR sequences. Materials and Methods. Eight C57BL/6J mice (BL6, male, aged 10 weeks) underwent a contrast-enhanced first-pass and 3D MR angiography (MRA) of the aorta and its main branches. All examinations were on a clinical 3 Tesla MR system (Siemens Healthcare, Erlangen, Germany). The clinical dose of 0.1 mmol/kg was administered in both probes. First, a time-resolved MRA (TWIST) was acquired during the first-pass to assess the arrival and washout of the contrast agent bolus. Subsequently, a high-resolution 3D MRA sequence (3D T1 FLASH) was acquired. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were calculated for all sequences. Results. The elastin-specific MR probe and the extravascular imaging agent (gadobutrol) enable high-quality MR angiograms in all animals. During the first-pass, the probes demonstrated a comparable peak enhancement (300.6 +/- 32.9 vs. 288.5 +/- 33.1, p > 0.05). Following the bolus phase, both agents showed a comparable intravascular enhancement (SNR: 106.7 +/- 11 vs. 102.3 +/- 5.3; CNR 64.5 +/- 7.4 vs. 61.1 +/- 7.2, p > 0.05). Both agents resulted in a high image quality with no statistical difference (p > 0.05). Conclusion. The novel elastin-specific molecular probe enables the performance of first-pass and late 3D MR angiography with an intravascular contrast enhancement and image quality comparable to a clinically used extravascular contrast agent

How pollen tubes fight for food: the impact of sucrose carriers and invertases of Arabidopsis thaliana on pollen development and pollen tube growth

Pollen tubes of higher plants grow very rapidly until they reach the ovules to fertilize the female gametes. This growth process is energy demanding, however, the nutrition strategies of pollen are largely unexplored. Here, we studied the function of sucrose transporters and invertases during pollen germination and pollen tube growth. RT-PCR analyses, reporter lines and knockout mutants were used to study gene expression and protein function in pollen. The genome of Arabidopsis thaliana contains eight genes that encode functional sucrose/H+ symporters. Apart from AtSUC2, which is companion cell specific, all other AtSUC genes are expressed in pollen tubes. AtSUC1 is present in developing pollen and seems to be the most important sucrose transporter during the fertilization process. Pollen of an Atsuc1 knockout plant contain less sucrose and have defects in pollen germination and pollen tube growth. The loss of other sucrose carriers affects neither pollen germination nor pollen tube growth. A multiple knockout line Atsuc1Atsuc3Atsuc8Atsuc9 shows a phenotype that is comparable to the Atsuc1 mutant line. Loss of AtSUC1 can`t be complemented by AtSUC9, suggesting a special function of AtSUC1. Besides sucrose carriers, pollen tubes also synthesize monosaccharide carriers of the AtSTP family as well as invertases. We could show that AtcwINV2 and AtcwINV4 are expressed in pollen, AtcwINV1 in the transmitting tissue and AtcwINV5 in the funiculi of the ovary. The vacuolar invertase AtVI2 is also expressed in pollen, and a knockout of AtVI2 leads to a severe reduction in pollen germination. Our data indicate that AtSUC1 mediated sucrose accumulation during late stages of pollen development and cleavage of vacuolar sucrose into monosaccharides is important for the process of pollen germination.</p

Dual-probe molecular MRI for the in vivo characterization of atherosclerosis in a mouse model: Simultaneous assessment of plaque inflammation and extracellularmatrix remodeling

Molecular MRI is a promising in-vivo modality to detect and quantify morphological and molecular vessel-wall changes in atherosclerosis. The combination of different molecular biomarkers may improve the risk stratification of patients. This study aimed to investigate the feasibility of simultaneous visualization and quantification of plaque-burden and inflammatory activity by dual-probe molecular MRI in a mouse-model of progressive atherosclerosis and in response-to-therapy. Homozygous apolipoprotein E knockout mice (ApoE-/-) were fed a high-fat-diet (HFD) for up to four-months prior to MRI of the brachiocephalic-artery. To assess response-to-therapy, a statin was administered for the same duration. MR imaging was performed before and after administration of an elastin-specific gadolinium-based and a macrophage-specific iron-oxide-based probe. Following in-vivo MRI, samples were analyzed using histology, immunohistochemistry, inductively-coupled-mass-spectrometry and laser-inductively-coupled-mass-spectrometry. In atherosclerotic-plaques, intraplaque expression of elastic-fibers and inflammatory activity were not directly linked. While the elastin-specific probe demonstrated the highest accumulation in advanced atherosclerotic-plaques after four-months of HFD, the iron-oxide-based probe showed highest accumulation in early atherosclerotic-plaques after two-months of HFD. In-vivo measurements for the elastin and iron-oxide-probe were in good agreement with ex-vivo histopathology (Elastica-van-Giesson stain: y = 298.2 + 5.8, R2 = 0.83, p < 0.05; Perls' Prussian-blue-stain: y = 834.1 + 0.67, R2 = 0.88, p < 0.05). Contrast-to-noise-ratio (CNR) measurements of the elastin probe were in good agreement with ICP-MS (y = 0.11x-11.3, R² = 0.73, p < 0.05). Late stage atherosclerotic-plaques displayed the strongest increase in both CNR and gadolinium concentration (p < 0.05). The gadolinium probe did not affect the visualization of the iron-oxide-probe and vice versa. This study demonstrates the feasibility of simultaneous assessment of plaque-burden and inflammatory activity by dual-probe molecular MRI of progressive atherosclerosis. The in-vivo detection and quantification of different MR biomarkers in a single scan could be useful to improve characterization of atherosclerotic-lesions

Интеллектуальные энергосистемы. Т. 3

Настоящий сборник содержит материалы V Международного молодежного форума «Интеллектуальные энергосистемы», проведенного 9 - 13 октября 2017г. на базе Энергетического института Томского политехнического университета

Iron Oxide Nanoparticles for Visualization of Prostate Cancer in MRI

Prostate cancer (PCa) is one of the most common cancers in men. For detection and diagnosis of PCa, non-invasive methods, including magnetic resonance imaging (MRI), can reduce the risk potential of surgical intervention. To explore the molecular characteristics of the tumor, we investigated the applicability of ferumoxytol in PCa in a xenograft mouse model in two different tumor volumes, 500 mm3 and 1000 mm3. Macrophages play a key role in tumor progression, and they are able to internalize iron-oxide particles, such as ferumoxytol. When evaluating T2*-weighted sequences on MRI, a significant decrease of signal intensity between pre- and post-contrast images for each tumor volume (n = 14; p < 0.001) was measured. We, furthermore, observed a higher signal loss for a tumor volume of 500 mm3 than for 1000 mm3. These findings were confirmed by histological examinations and laser ablation inductively coupled plasma-mass spectrometry. The 500 mm3 tumors had 1.5% iron content (n = 14; σ = 1.1), while the 1000 mm3 tumors contained only 0.4% iron (n = 14; σ = 0.2). In vivo MRI data demonstrated a correlation with the ex vivo data (R2 = 0.75). The results of elemental analysis by inductively coupled plasma-mass spectrometry correlated strongly with the MRI data (R2 = 0.83) (n = 4). Due to its long retention time in the blood, biodegradability, and low toxicity to patients, ferumoxytol has great potential as a contrast agent for visualization PCa.SonderforschungsbereichDeutsche ForschungsgemeinschaftPeer Reviewe

Elastin-specific MRI of extracellular matrix-remodelling following hepatic radiofrequency-ablation in a VX2 liver tumor model

Hepatic radiofrequency ablation (RFA) induces a drastic alteration of the biomechanical environment in the peritumoral liver tissue. The resulting increase in matrix stiffness has been shown to significantly influence carcinogenesis and cancer progression after focal RF ablation. To investigate the potential of an elastin-specific MR agent (ESMA) for the assessment of extracellular matrix (ECM) remodeling in the periablational rim following RFA in a VX2 rabbit liver tumor-model, twelve New-Zealand-White-rabbits were implanted in the left liver lobe with VX2 tumor chunks from donor animals. RFA of tumors was performed using a perfused RF needle-applicator with a mean tip temperature of 70 degrees C. Animals were randomized into four groups for MR imaging and scanned at four different time points following RFA (week 0 [baseline], week 1, week 2 and week 3 after RFA), followed by sacrifice and histopathological analysis. ESMA-enhanced MR imaging was used to assess ECM remodeling. Gadobutrol was used as a third-space control agent. Molecular MR imaging using an elastin-specific probe demonstrated a progressive increase in contrast-to-noise ratio (CNR) (week 3: ESMA: 28.1 +/- 6.0; gadobutrol: 3.5 +/- 2.0), enabling non-invasive imaging of the peritumoral zone with high spatial-resolution, and accurate assessment of elastin deposition in the periablational rim. In vivo CNR correlated with ex vivo histomorphometry (ElasticaVanGiesson-stain, y=1.2x - 1.8, R-2=0.89, p<0.05) and gadolinium concentrations at inductively coupled mass spectroscopy (ICP-MS, y=0.04x+1.2, R-2=0.95, p<0.05). Laser-ICP-MS confirmed colocalization of elastin-specific probe with elastic fibers. Following thermal ablation, molecular imaging using an elastin-specific MR probe is feasible and provides a quantifiable biomarker for the assessment of the ablation-induced remodeling of the ECM in the periablational rim

Development and Evaluation of new low-molecular probes for the characterization of vascular diseases by magnetic resonance imaging (MRI)

Atherosklerose ist von fundamentaler Bedeutung für zahlreiche kardiovaskulärer Folgeerkrankungen. Klinisch äußert sie sich meist erst nach Jahren oder Jahrzehnten durch Symptome ihrer Folgeerkrankungen. Die zentralen pathophysiologischen Faktoren dieser Erkrankung sind Endothelzelldysfunktionen, Ablagerungen von Blutfetten in den Gefäßwänden und chronische Entzündungsreaktionen. Kennzeichnend für Atherosklerose ist also die Ansammlung von proinflammatorischen Zellen und extrazellulären Matrixproteinen, wie Elastin, in der Gefäßintima. Ein Risiko für Atherosklerose ist die Plaqueruptur mit der subsequenten Bildung von Thromben, welche zu Herzinfarkten oder Schlaganfällen führen können. Präventionsansätze können die Mortalität dieser Krankheit drastisch senken. Die molekulare Bildgebung ermöglicht die nicht-invasive in vivo Visualisierung und Quantifizierung biologischer Prozesse auf molekularer und zellulärer Ebene. Diese Dissertation hat sich mit dem Potenzial der in vivo Magnetresonanztomographie für die molekulare Bildgebung von Atherosklerose befasst und neue Möglichkeiten in der Detektion dieser Erkrankung aufgezeigt. Zum einen wurde im ersten Teil dieser Dissertation gezeigt, dass die elastinspezifische Sonde ähnliche Eigenschaften für die Durchführung von MR-Angiographien hat, wie klinisch verwendete Kontrastmittel. Dies ist von hoher Relevanz für die potentielle klinische Translation einer solchen Sonde. Zum anderen konnte im zweiten Teil dieser Dissertation gezeigt werden, dass auf Basis einer simultanen molekularen MRT mit zwei Sonden die Charakterisierung der Plaquelast und der entzündlichen Aktivität von progressiver Atherosklerose im Mausmodell möglich ist. Der in vivo Nachweis und die Quantifizierung dieser mit Plaque-Instabilität verbundenen Biomarker in einem einzigen Scan können den Nachweis von instabilen Plaques ermöglichen und dadurch die Risikostratifizierung und Behandlungsführung von Patienten verbessern. Die duale Anwendung der elastin- und eisenoxidspezifischen Sonden bildet somit ein neuartiges Bildgebungsinstrument zur in vivo Charakterisierung der Plaqueruptur bei Atherosklerose.Atherosclerosis is of fundamental importance for numerous cardiovascular sequelae. Clinically, it usually manifests itself only after years or decades by symptoms of their sequelae. The central pathophysiological factors of this disease are endothelial cell dysfunction, deposits of blood lipids in the vessel walls and chronic inflammatory reactions. Characteristic of atherosclerosis is therefore the accumulation of proinflammatory cells and extracellular matrix proteins, such as elastin, in the vascular intima. A risk of atherosclerosis is plaque rupture with the subsequent formation of thrombi, which can lead to heart attacks or strokes. Prevention approaches can drastically reduce the mortality of this disease. Molecular imaging enables the non-invasive in vivo visualization and quantification of biological processes at the molecular and cellular level. This dissertation deals with the potential of in vivo magnetic resonance tomography for the molecular imaging of atherosclerosis and demonstrates new possibilities in the detection of this disease. On the one hand, the first part of this thesis demonstrated that the elastin-specific probe has similar properties for performing MR angiography as clinically used contrast agents. This is of high relevance for the potential clinical translation of such a probe. On the other hand, in the second part of this thesis it could be shown that a simultaneous molecular MRI with two probes enables the characterization of the plaque burden and the inflammatory activity of progressive atherosclerosis in a mouse model. The in vivo detection and quantification of these plaque instability-associated biomarkers in a single scan can enable detection of unstable plaques, thereby improving patient risk stratification and treatment guidance. The dual application of the elastin and iron oxide specific probes thus forms a novel imaging instrument for the in vivo characterization of plaque rupture in atherosclerosis

Planar Microwave Sensor for Theranostic Therapy of Organic Tissue Based on Oval Split Ring Resonators

Microwave sensors in medical environments play a significant role due to the contact-less and non-invasive sensing mechanism to determine dielectric properties of tissue. In this work, a theranostic sensor based on Split Ring Resonators (SRRs) is presented that provides two operation modes to detect and treat tumor cells, exemplary in the liver. For the detection mode, resonance frequency changes due to abnormalities are evaluated, and in the treatment mode, microwave ablation is performed. The planar sensor structure can be integrated into a needle like a surgery tool that evokes challenges concerning size limitations and biocompatibility. To meet the size requirements and provide a reasonable operating frequency, properties of oval shaped SRRs are investigated. By elongating the radius of the SRR in one direction, the resonance frequency can be decreased significantly compared to circular SRR by a factor of two below 12 GHz. In order to validate the detection and treatment characteristics of the sensor, full wave simulations and measurements are examined. Clear resonance shifts are detected for loading the sensor structures with phantoms mimicking healthy and malignant tissue. For treatment mode evaluation, ex vivo beef liver tissue was ablated leading to a lesion zone 1.2 cm × 1 cm × 0.3 cm with a three minute exposure of maximum 2.1 W