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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
291

Improving Execution Speed of Models Implemented in NetLogo

Railsback, Steven, Ayllón, Daniel, Berger, Uta, Grimm, Volker, Lytinen, Steven, Sheppard, Colin, Thiele, Jan C. 30 March 2017 (has links) (PDF)
NetLogo has become a standard platform for agent-based simulation, yet there appears to be widespread belief that it is not suitable for large and complex models due to slow execution. Our experience does not support that belief. NetLogo programs often do run very slowly when written to minimize code length and maximize clarity, but relatively simple and easily tested changes can almost always produce major increases in execution speed. We recommend a five-step process for quantifying execution speed, identifying slow parts of code, and writing faster code. Avoiding or improving agent filtering statements can often produce dramatic speed improvements. For models with extensive initialization methods, reorganizing the setup procedure can reduce the initialization effort in simulation experiments. Programming the same behavior in a different way can sometimes provide order-of-magnitude speed increases. For models in which most agents do nothing on most time steps, discrete event simulation—facilitated by the time extension to NetLogo—can dramatically increase speed. NetLogo’s BehaviorSpace tool makes it very easy to conduct multiple-model-run experiments in parallel on either desktop or high performance cluster computers, so even quite slow models can be executed thousands of times. NetLogo also is supported by efficient analysis tools, such as BehaviorSearch and RNetLogo, that can reduce the number of model runs and the effort to set them up for (e.g.) parameterization and sensitivity analysis.
292

Cognitive Investments in Academic Success: The Role of Need for Cognition at University

Grass, Julia, Strobel, Alexander, Strobel, Anja 26 June 2017 (has links) (PDF)
Previous research has shown that Need for Cognition (NFC), the individual tendency to engage in and enjoy cognitive endeavors, contributes to academic performance. Most studies on NFC and related constructs have thereby focused on grades to capture tertiary academic success. This study aimed at a more comprehensive approach on NFC’s meaning to success in university. We examined not only performance but also rather affective indicators of success. The current sample consisted of 396 students of different subjects with a mean age of 24 years (139 male). All participants took part in an online survey that assessed NFC together with school performance and further personality variables via self-report. Success in university was comprehensively operationalized including performance, satisfaction with one’s studies, and thoughts about quitting/changing one’s major as indicators. The value of NFC in predicting tertiary academic success was examined with correlation analyses and path analysis. NFC significantly correlated with all success variables with the highest correlation for study satisfaction. Path analysis confirmed the importance of NFC for study satisfaction showing that NFC had a significant direct effect on study satisfaction and via this variable also a significant indirect effect on termination thoughts. This study clearly indicates that NFC broadly contributes to the mastery of academic requirements and that it is worthwhile to intensify research on NFC in the context of tertiary education.
293

Open Access-Tag 2016 "Aktiv sein – etwas bewegen"

Partmann, Michael 17 November 2016 (has links) (PDF)
Das vorliegende Grußwort wurde anlässlich des Open Access-Tages 2016 der Technischen Universität Chemnitz durch den Referenten (Schwerpunkt Forschung und wissenschaftlicher Nachwuchs) im Büro des Rektors der TU Chemnitz gehalten. Der Redner ging auf die zunehmende Bedeutung von Open Access ein und hob die diesbezüglichen Services der Universitätsbibliothek hervor. / The welcome speech was held on Open Access Day 2016 of Technische Universität Chemnitz by Michael Partmann, Assistant (specialized in Research and Junior Researchers) in the Rector’s Office. The speaker mentioned the increasing importance of Open Access and highlighted the relevant services of the University Library.
294

Finanzierung von Open Access - bisher und heute / Open-Access-Funding - so far and now

Blumtritt, Ute 17 June 2013 (has links) (PDF)
Die Universitätsbibliothek Chemnitz bietet seit vielen Jahren verschiedene Services zum Open-Access-Publizieren für die Wissenschaftler der Technischen Universität. Dazu gehören u.a. das digitale Volltextarchiv, das Open Journal System und der Universitätsverlag. Wissenschaftliche Autoren können sowohl auf dem Goldenen als auch auf dem Grünen Weg Open Access publizieren. In diesem Jahr wurde erstmals ein Publikationsfonds für die Veröffentlichung von Open-Access-Artikeln eingerichtet. Es wurden Mittel von der Deutschen Forschungsgemeinschaft und der Technischen Universität Chemnitz bereitgestellt. Damit können die Universitätsangehörigen die finanzielle Übernahme von Publikationsgebühren für Open-Access-Artikel bei der Bibliothek beantragen. Sind die Fördervoraussetzungen erfüllt, erfolgt der Zuschlag in der Reihenfolge des Eingangs der Rechnung. / Since many years the University Library of Chemnitz offers several services regarding open access publication to the scientists of Chemnitz University of Technology. Among others this includes a digital archive, a Journal Management System, and the University Press. It is possible to publish on Golden Way of Open Access as well as on Green Way. This year we offer for the first time a publication funds for the publication of open access articles. The financial resources are provided by Deutsche Forschungsgemeinschaft and Chemnitz University of Technology. Please apply for financial support at the University Library if you need to pay a publication fee for open access articles. If the criteria for financial support are met an agreement will be made in order of invoices received.
295

Neonatal assessment in the delivery room – Trial to Evaluate a Specified Type of Apgar (TEST-Apgar)

Rüdiger, Mario, Braun, Nicole, Aranda, Jacob, Aguar, Marta, Bergert, Renate, Bystricka, Alica, Dimitriou, Gabriel, El-Atawi, Khaled, Ifflaender, Sascha, Jung, Philipp, Matasova, Katarina, Ojinaga, Violeta, Petruskeviciene, Zita, Roll, Claudia, Schwindt, Jens, Simma, Burkhard, Staal, Nanette, Valencia, Gloria, Vasconcellos, Maria Gabriela, Veinla, Maie, Vento, Máximo, Weber, Benedikt, Wendt, Anke, Yigit, Sule, Zotter, Heinz, Küster, Helmut 23 July 2015 (has links) (PDF)
Background: Since an objective description is essential to determine infant’s postnatal condition and efficacy of interventions, two scores were suggested in the past but weren’t tested yet: The Specified-Apgar uses the 5 items of the conventional Apgar score; however describes the condition regardless of gestational age (GA) or resuscitative interventions. The Expanded-Apgar measures interventions needed to achieve this condition. We hypothesized that the combination of both (Combined-Apgar) describes postnatal condition of preterm infants better than either of the scores alone. Methods: Scores were assessed in preterm infants below 32 completed weeks of gestation. Data were prospectively collected in 20 NICU in 12 countries. Prediction of poor outcome (death, severe/moderate BPD, IVH, CPL and ROP) was used as a surrogate parameter to compare the scores. To compare predictive value the AUC for the ROC was calculated. Results: Of 2150 eligible newborns, data on 1855 infants with a mean GA of 286/7± 23/7 weeks were analyzed. At 1 minute, the Combined-Apgar was significantly better in predicting poor outcome than the Specified- or Expanded-Apgar alone. Of infants with a very low score at 5 or 10 minutes 81% or 100% had a poor outcome, respectively. In these infants the relative risk (RR) for perinatal mortality was 24.93 (13.16-47.20) and 31.34 (15.91-61.71), respectively. Conclusion: The Combined-Apgar allows a more appropriate description of infant’s condition under conditions of modern neonatal care. It should be used as a tool for better comparison of group of infants and postnatal interventions.
296

Hibernoma – two patients with a rare lipoid soft-tissue tumour

Daubner, Dirk, Spieth, Stephanie, Pablik, Jessica, Paulus, Tobias, Laniado, Michael, Zöphel, Klaus 24 July 2015 (has links) (PDF)
Background: Hibernomas are rare benign soft-tissue tumours arising from brown fat tissue. Although imaging characteristics are not specific certain imaging features, common locations and patient demographics may suggest hibernoma as a differential diagnosis. Case presentation: We report on two 48-year-old male patients with hibernoma. The tumour presented with local swelling of the inguinal region in the first patient and was an incidental imaging finding in the second patient. Imaging included magnetic resonance imaging in both patients and computed tomography as well as 18 F-fluorodeoxyglucose positron emission tomography-computed tomography in the second patient. In both cases histological diagnosis was initially based on excisional and needle core biopsy, respectively. Complete surgical resection confirmed the diagnosis of hibernoma thereafter. Conclusion: In soft tissue tumours with fatty components hibernoma may be included into the differential diagnosis. Because of the risk of sampling errors in hibernoma-like tissue components of myxoid and well-differentiated liposarcoma, complete resection is mandatory. This article also reviews the current imaging literature of hibernomas.
297

Soil Chemical and Microbial Properties in a Mixed Stand of Spruce and Birch in the Ore Mountains (Germany) - A Case Study

Schua, Karoline, Wende, Stefan, Wagner, Sven, Feger, Karl-Heinz 27 July 2015 (has links) (PDF)
A major argument for incorporating deciduous tree species in coniferous forest stands is their role in the amelioration and stabilisation of biogeochemical cycles. Current forest management strategies in central Europe aim to increase the area of mixed stands. In order to formulate statements about the ecological effects of mixtures, studies at the stand level are necessary. In a mixed stand of Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth) in the Ore Mountains (Saxony, Germany), the effects of these two tree species on chemical and microbial parameters in the topsoil were studied at one site in the form of a case study. Samples were taken from the O layer and A horizon in areas of the stand influenced by either birch, spruce or a mixture of birch and spruce. The microbial biomass, basal respiration, metabolic quotient, pH-value and the C and N contents and stocks were analysed in the horizons Of, Oh and A. Significantly higher contents of microbial N were observed in the Of and Oh horizons in the birch and in the spruce-birch strata than in the stratum containing only spruce. The same was found with respect to pH-values in the Of horizon and basal respiration in the Oh horizon. Compared to the spruce stratum, in the birch and spruce-birch strata, significantly lower values were found for the contents of organic C and total N in the A horizon. The findings of the case study indicated that single birch trees have significant effects on the chemical and microbial topsoil properties in spruce-dominated stands. Therefore, the admixture of birch in spruce stands may distinctly affect nutrient cycling and may also be relevant for soil carbon sequestration. Further studies of these functional aspects are recommended.
298

Effect of language task demands on the neural response during lexical access: a functional magnetic resonance imaging study

Gan, Gabriela, Büchel, Christian, Isel, Frédéric 28 November 2013 (has links) (PDF)
This study examined the effects of linguistic task demands on the neuroanatomical localization of the neural response related to automatic semantic processing of concrete German nouns combining the associative priming paradigm with functional magnetic resonance imaging (fMRI). To clarify the functional role of the inferior frontal gyrus (IFG) for semantic processing with respect to semantic decision making compared to semantic processing per se, we used a linguistic task that involved either a binary decision process (i.e., semantic categorization; Experiment 1) or not (i.e., silently thinking about a word's meaning; Experiment 2). We observed associative priming effects indicated as neural suppression in bilateral superior temporal gyri (STG), anterior cingulate cortex (ACC), occipito-temporal brain areas, and in medial frontal brain areas independently of the linguistic task. Inferior parietal brain areas were more active for silently thinking about a word's meaning compared to semantic categorization. A conjunction analysis of linguistic task revealed that both tasks activated the same left-lateralized occipito-temporo-frontal network including the IFG. Contrasting neural associative priming effects across linguistic task demands, we found a significant interaction in the right IFG. The present fMRI data give rise to the assumption that activation of the left inferior frontal gyrus (LIFG) in the semantic domain might be important for semantic processing in general and not only for semantic decision making. These findings contrast with a recent study regarding the role of the LIFG for binary decision making in the lexical domain (Wright et al. 2011).
299

Autoregressive Higher-Order Hidden Markov Models: Exploiting Local Chromosomal Dependencies in the Analysis of Tumor Expression Profiles

Seifert, Michael, Abou-El-Ardat, Khalil, Friedrich, Betty, Klink, Barbara, Deutsch, Andreas 07 May 2015 (has links) (PDF)
Changes in gene expression programs play a central role in cancer. Chromosomal aberrations such as deletions, duplications and translocations of DNA segments can lead to highly significant positive correlations of gene expression levels of neighboring genes. This should be utilized to improve the analysis of tumor expression profiles. Here, we develop a novel model class of autoregressive higher-order Hidden Markov Models (HMMs) that carefully exploit local data-dependent chromosomal dependencies to improve the identification of differentially expressed genes in tumor. Autoregressive higher-order HMMs overcome generally existing limitations of standard first-order HMMs in the modeling of dependencies between genes in close chromosomal proximity by the simultaneous usage of higher-order state-transitions and autoregressive emissions as novel model features. We apply autoregressive higher-order HMMs to the analysis of breast cancer and glioma gene expression data and perform in-depth model evaluation studies. We find that autoregressive higher-order HMMs clearly improve the identification of overexpressed genes with underlying gene copy number duplications in breast cancer in comparison to mixture models, standard first- and higher-order HMMs, and other related methods. The performance benefit is attributed to the simultaneous usage of higher-order state-transitions in combination with autoregressive emissions. This benefit could not be reached by using each of these two features independently. We also find that autoregressive higher-order HMMs are better able to identify differentially expressed genes in tumors independent of the underlying gene copy number status in comparison to the majority of related methods. This is further supported by the identification of well-known and of previously unreported hotspots of differential expression in glioblastomas demonstrating the efficacy of autoregressive higher-order HMMs for the analysis of individual tumor expression profiles. Moreover, we reveal interesting novel details of systematic alterations of gene expression levels in known cancer signaling pathways distinguishing oligodendrogliomas, astrocytomas and glioblastomas.
300

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery

Spieth, Peter M., Güldner, Andreas, Uhlig, Christopher, Bluth, Thomas, Kiss, Thomas, Schultz, Marcus J., Pelosi, Paolo, Koch, Thea, Gamba de Abreu, Marcelo 17 April 2015 (has links) (PDF)
Background: General anesthesia usually requires mechanical ventilation, which is traditionally accomplished with constant tidal volumes in volume- or pressure-controlled modes. Experimental studies suggest that the use of variable tidal volumes (variable ventilation) recruits lung tissue, improves pulmonary function and reduces systemic inflammatory response. However, it is currently not known whether patients undergoing open abdominal surgery might benefit from intraoperative variable ventilation. Methods/Design: The PROtective VARiable ventilation trial ('PROVAR') is a single center, randomized controlled trial enrolling 50 patients who are planning for open abdominal surgery expected to last longer than 3 hours. PROVAR compares conventional (non-variable) lung protective ventilation (CV) with variable lung protective ventilation (VV) regarding pulmonary function and inflammatory response. The primary endpoint of the study is the forced vital capacity on the first postoperative day. Secondary endpoints include further lung function tests, plasma cytokine levels, spatial distribution of ventilation assessed by means of electrical impedance tomography and postoperative pulmonary complications. Discussion: We hypothesize that VV improves lung function and reduces systemic inflammatory response compared to CV in patients receiving mechanical ventilation during general anesthesia for open abdominal surgery longer than 3 hours. PROVAR is the first randomized controlled trial aiming at intra- and postoperative effects of VV on lung function. This study may help to define the role of VV during general anesthesia requiring mechanical ventilation.

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