Analysis of Boundary Layer Structure in a Shock-generated Plasma Flow. Part 1 - Equilibrium Ionization

Analysis of convective laminar boundary layer structures in high density shock heated argon plasma flo

The closer, the better? Processing relations between picture elements in historical paintings

The present eye-tracking study investigated how audio explanations influence perception and the cognitive processing of historical paintings. Spatially close and distant pairs of picture elements and their semantic relations were named in an audio text either immediately after each other or with descriptions of other elements in between. It was assumed that the number of backward fixation counts on the first of the two mentioned related picture elements should be higher if they are spatially close rather than spatially distant. There should also be more backward fixation counts if the elements are named temporally close rather than temporally distant. Similar predictions were made for the retention of these picture elements and their relations. A 2x2x2 within-subject design (n=36) with spatial distance (close vs. distant), temporal distance (close vs. distant) and painting (Leutze vs. West) revealed more background fixation counts for spatially close compared to spatially distant elements but just for the Leutze painting. Accordingly, the relations between the spatially close pairs were retained better than between the spatially distant pairs in the Leutze painting but vice versa for the West painting. The results are discussed with regard to the spatial contiguity principle of multimedia learning and research on text coherence

Learning with Pictures and Accompanying Audio-Texts: Conflict Regulation, Narrative Processing, and Aesthetic Evaluation

History paintings are a special form of pictures, as they can be used not only as historical documents, but also tell a story and are exhibited in galleries as artworks. However, history paintings often contain discrepancies between their depiction and reality that are frequently named in accompanying audio-texts. The aim of the present studies was to examine theories from three fields (picture as 1. historical document, 2. narrative, 3. artwork). These theories assume that naming of discrepancies between a picture and reality should affect the processing of the picture, the memory for content of the picture, and the evaluation of the picture. Study 1 showed that recipients fixated the content of the picture longer when it was named with discrepancies than without. This indicates that conflicts were recognized by the viewers. With regard to conflict regulation strategies, recipients did not process source information longer, nor did they report higher interest in further information when discrepancies were named than when discrepancies were not named. Thus, the results of Study 1 do not support neither sourcing nor information seeking as conflict regulation strategies of the recipients. In Study 2, recipients rated the trustworthiness of the picture document lower when discrepancies were named but not explained compared to when discrepancies were not named. As expected, explaining the discrepancies through the benevolent intentions of the artist compensated for the negative effect of naming discrepancies. This suggests that viewers used information about the source along with information about the content to evaluate the trustworthiness of the picture document. The recall of discrepant picture content was not better when discrepancies were named than without naming of discrepancies, but an exploratory analysis revealed that the recall of consistent pictorial content was worse when discrepancies were named. In Study 3, on the aesthetics of the picture, recipients did not rate their subjective understanding worse when discrepancies were named and not explained compared to when discrepancies were not named. However, aesthetic liking of the picture was significantly lower when discrepancies were named and not explained compared to not naming discrepancies at all. Moreover, as expected, this effect was compensated by an explanation of the discrepancies. There was neither an effect of discrepancies nor explanation on surprise, interest, and confusion. The results show that fluency is important for aesthetic liking. Studies 1,2,3 did not show consistent results on whether naming discrepancies has a negative effect on the viewers’ transportation. In Study 4, an audio text annotated two different picture documents about the same event. Discrepancies between the pictures were always named and differences in the artists' intentions were manipulated. Either artist’s were described with differences in benevolence (one with propagandistic intention and one with a documentary intention) or without difference in benevolence (either both with a propagandistic intention or both with no intentions at all) The results of Study 4 did not show that recipients engaged in more sourcing and less information seeking when the source information was useful for conflict regulation than when the source information was not useful for conflict regulation. The present work extends theories in the respective fields and serves a better understanding of the design of audio texts in museums

Clinical implications of the anisotropic analytical algorithm for IMRT treatment planning and verification

PURPOSE: To determine the implications of the use of the Anisotropic Analytical Algorithm(AAA) for the production and dosimetric verification of IMRT plans for treatments of the prostate, parotid, nasopharynx and lung. METHODS: 72 IMRT treatment plans produced using the Pencil Beam Convolution (PBC)algorithm were recalculated using the AAA and the dose distributions compared. 24 of the plans were delivered to inhomogeneous phantoms and verification measurements made using a pinpoint ionisation chamber. The agreement between the AAA and measurement was determined. RESULTS: Small differences were seen in the prostate plans, with the AAA predicting slightly lower minimum PTV doses. In the parotid plans, there were small increases in the lens and contralateral parotid doses while the nasopharyngeal plans revealed a reduction in the volume of the PTV covered by the 95% isodose (the V95%) when the AAA was used. Large changes were seen in the lung plans, the AAA predicting reductions in the minimum PTV dose and large reductions in the V95%. The AAA also predicted small increases in the mean dose to the normal lung and the V20. In the verification measurements, all AAA calculations were within 3% or 3.5mm distance to agreement of the measured doses. Conclusions: The AAA should be used in preference to the PBC algorithm for treatments involving low density tissue but this may necessitate re-evaluation of plan acceptability criteria. Improvements to the Multi-Resolution Dose Calculation algorithm used in the inverse planning are required to reduce the convergence error in the presence of lung tissue. There was excellent agreement between the AAA and verification measurements for all sites

Optimization of extracranial stereotactic radiation therapy of small lung lesions using accurate dose calculation algorithms

BACKGROUND: The aim of this study was to compare and to validate different dose calculation algorithms for the use in radiation therapy of small lung lesions and to optimize the treatment planning using accurate dose calculation algorithms. METHODS: A 9-field conformal treatment plan was generated on an inhomogeneous phantom with lung mimics and a soft tissue equivalent insert, mimicking a lung tumor. The dose distribution was calculated with the Pencil Beam and Collapsed Cone algorithms implemented in Masterplan (Nucletron) and the Monte Carlo system XVMC and validated using Gafchromic EBT films. Differences in dose distribution were evaluated. The plans were then optimized by adding segments to the outer shell of the target in order to increase the dose near the interface to the lung. RESULTS: The Pencil Beam algorithm overestimated the dose by up to 15% compared to the measurements. Collapsed Cone and Monte Carlo predicted the dose more accurately with a maximum difference of -8% and -3% respectively compared to the film. Plan optimization by adding small segments to the peripheral parts of the target, creating a 2-step fluence modulation, allowed to increase target coverage and homogeneity as compared to the uncorrected 9 field plan. CONCLUSION: The use of forward 2-step fluence modulation in radiotherapy of small lung lesions allows the improvement of tumor coverage and dose homogeneity as compared to non-modulated treatment plans and may thus help to increase the local tumor control probability. While the Collapsed Cone algorithm is closer to measurements than the Pencil Beam algorithm, both algorithms are limited at tissue/lung interfaces, leaving Monte-Carlo the most accurate algorithm for dose prediction

Intensity-modulated radiation therapy (IMRT) vs. 3D conformal radiotherapy (3DCRT) in locally advanced rectal cancer (LARC): dosimetric comparison and clinical implications

<p>Abstract</p> <p>Purpose</p> <p>To compare target dose distribution, comformality, normal tissue avoidance, and irradiated body volume (IBV) in 3DCRT using classic anatomical landmarks (c3DCRT), 3DCRT fitting the PTV (f3DCRT), and intensity-modulated radiation therapy (IMRT) in patients with locally advanced rectal cancer (LARC).</p> <p>Materials and methods</p> <p>Fifteen patients with LARC underwent c3DCRT, f3DCRT, and IMRT planning. Target definition followed the recommendations of the ICRU reports No. 50 and 62. OAR (SB and bladder) constraints were D5 ≤ 50 Gy and Dmax < 55 Gy. PTV dose prescription was defined as PTV95 ≥ 45 Gy and PTVmin ≥ 35 Gy. Target coverage was evaluated with the D95, Dmin, and Dmax. Target dose distribution and comformality was evaluated with the homogeneity indices (HI) and Conformity Index (CI). Normal tissue avoidance of OAR was evaluated with the D5 and V40. IBV at 5 Gy (V5), 10 Gy (V10), and 20 Gy (V20) were calculated.</p> <p>Results</p> <p>The mean GTV95, CTV95, and PTV95 doses were significantly lower for IMRT plans. Target dose distribution was more inhomogeneous after IMRT planning and 3DCRTplans had significantly lower CI. The V40 and D5 values for OAR were significantly reduced in the IMRT plans .V5 was greater for IMRT than for f3DCRT planning (p < 0.05) and V20 was smaller for IMRT plans(p < 0.05).</p> <p>Conclusions</p> <p>IMRT planning improves target conformity and decreases irradiation of the OAR at the expense of increased target heterogeneity. IMRT planning increases the IBV at 5 Gy or less but decreases the IBV at 20 Gy or more.</p

Exceptionally high incidence of symptomatic grade 2–5 radiation pneumonitis after stereotactic radiation therapy for lung tumors

<p>Abstract</p> <p>Background</p> <p>To determine the usefulness of dose volume histogram (DVH) factors for predicting the occurrence of radiation pneumonitis (RP) after application of stereotactic radiation therapy (SRT) for lung tumors, DVH factors were measured before irradiation.</p> <p>Methods</p> <p>From May 2004 to April 2006, 25 patients were treated with SRT at the University of Tokyo Hospital. Eighteen patients had primary lung cancer and seven had metastatic lung cancer. SRT was given in 6–7 fields with an isocenter dose of 48 Gy in four fractions over 5–8 days by linear accelerator.</p> <p>Results</p> <p>Seven of the 25 patients suffered from RP of symptomatic grade 2–5 according to the NCI-CTC version 3.0. The overall incidence rate of RP grade2 or more was 29% at 18 months after completing SRT and three patients died from RP. RP occurred at significantly increased frequencies in patients with higher conformity index (CI) (p = 0.0394). Mean lung dose (MLD) showed a significant correlation with V₅–V₂₀(irradiated lung volume) (p < 0.001) but showed no correlation with CI. RP did not statistically correlate with MLD. MLD had the strongest correlation with V₅.</p> <p>Conclusion</p> <p>Even in SRT, when large volumes of lung parenchyma are irradiated to such high doses as the minimum dose within planning target volume, the incidence of lung toxicity can become high.</p

Grit

Grit beschreibt das Ausmaß in welchem Personen Langzeitziele beharrlich und mit beständigem Interesse verfolgen. Dabei werden Rückschläge überwunden und Herausforderungen gemeistert. Bisherige Forschung konnte zeigen, dass Grit ein wichtiger Prädiktor von Erfolg im Hochleistungsbereich ist. Im Schulbereich war Grit im Vergleich zu anderen motivationalen- oder Persönlichkeitskonstrukten ein mäßiger bis nicht signifikanter Prädiktor. Bisherige Forschung kritisierte die starke Nähe zu Gewissenhaftigkeit und Selbstkontrolle. In dieser Studie wurde untersucht, ob Grit ein wichtiger Prädiktor von Erfolg im Studium ist, wo Langzeitziele relevant sind. Es wurden Annahmen zur externen- und Konstruktvalidität untersucht. Die Theorie der hierarchischen Ziele wurde verwendet, um Unterschiede zwischen Grit und Selbstkontrolle zu zeigen, die anschließend geprüft wurden. Es wurden insgesamt 220 Studierende der Rechtswissenschaften (80 Prozent weiblich, 20 Prozent männlich) am Juridicum der Universität Wien untersucht. Dazu wurde ein Online Fragebogen verwendet.Die TeilnehmerInnen wurden in einschlägigen Facebook Gruppen rekrutiert. Die Zweifaktoren-Struktur von Grit wurde in einer konfirmatorischen Faktorenanalyse bestätigt. Die Korrelationen zwischen den Subfaktoren sprechen für den hierarchischen Grit Faktor. Die Grit Skala zeigte gute Reliabilität in einer österreichischen Stichprobe. Grit korrelierte mit Mastery und Selbstwirksamkeitserwartung nicht aber mit Leistungszielorientierung. Es konnte gezeigt werden, dass Grit ein besserer Prädiktor als Selbstkontrolle für Erfolg im Studium (hohe Zielebene) ist. Es konnte nicht gezeigt werden, dass Selbstkontrolle der bessere Prädiktor für Erfolg auf niedriger Zielebene (Noten) ist. Auch war Grit kein Moderator für die enge des Zusammenhangs zwischen Zielen beider Hierarchieebenen. Die Ergebnisse werden unter Berücksichtigung bisheriger Forschung diskutiert.Grit describes the passion and perseverance for long-term goals. Gritty people follow their goals with constant interest despite setbacks or failure. Recent research showed that Grit is an important predictor for attainment in high-achieving contexts. In contrast researchers in schools could not confirm this effect. Grit had none or a small additional contribution on atteinment, after controlling for other motivational and personality constructs. Grit was criticized because of high correlation with conscientiousness and self-control. The aim of this study was to show that grit is a strong predictor for attainment in university where long-term goals matter. Construct and external validity of grit were explored. The theory of hierarchical goals was applied to examine differences in self-control and grit. A sample of 220 law students (80 percent female and 20 percent male) at the Juridicum, University of Vienna completed an online-questionnaire. They were recruitet in respective facebook groups. Evidence for the two-facor structure of grit could be established with confirmatory factor analysis. High correlation between the Subfactors indicate a higher-order-grit-factor. Reliabilty of the grit-scale was shown for an austrian sample. Grit was correlated with Mastery and self-efficacy but not with Achievement goal orientation. Grit was a better predictor than self-control for higher-order-goals (study sucess) but self-control was not a better predictor than grit for lower-order-goals (grades). Grit did‘nt influence the closeness of the link between higher- and lower-order-goals. The results were discussed and directions for further research given