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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.
61

A Fiber-Reinforced Architectural Concrete for the Newly Designed Façade of the Poseidon Building in Frankfurt am Main

Funke, Henrik L., Gelbrich, Sandra, Ehrlich, Andreas, Kroll, Lothar January 2014 (has links)
In the course of revitalizing the Poseidon Building in Frankfurt, an energetically optimized façade, made of architectural concrete was developed. The development of a fiber-reinforced architectural concrete had to consider the necessary mechanical strength, design technology and surface quality. The fiber-reinforced architectural concrete has a compressive strength of 104.1 MPa and a 3-point bending tensile strength of 19.5 MPa. Beyond that, it was ensured that the fiber-reinforced high-performance concrete had a high durability, which has been shown by the capillary suction of de-icing solution and freeze thaw test with a weathering of abrasion of 113 g/m² after 28 freeze-thaw cycles and a mean water penetration depth of 11 mm.
62

Gemeinsam ist man weniger allein: Die Universitätsbibliothek Chemnitz knüpft Netzwerke innerhalb der TU Chemnitz

Malz, Angela 19 November 2015 (has links)
Die Zeiten, in denen eine Universität nur aus Fakultäten, zentralen Einrichtungen und der Verwaltung bestand, sind lange vorbei. Eine Vielzahl von Projekten und Initiativen sind ins Leben gerufen worden und viele von ihnen haben das Ziel, den Studierenden das Studium zu erleichtern, ihnen bei der Lösung von Problemen zu helfen und sie beim Übergang in die Berufstätigkeit zu unterstützen. In der TU Chemnitz gibt es beispielsweise TU4U, das Zentrum für den wissenschaftlichen Nachwuchs, das Gründernetzwerk SAXEED. Und dann gibt es noch die Universitätsbibliothek, die verwundert auf die Kursprogramme der Projekte schaut und darin Themen findet wie wissenschaftliches Arbeiten, Recherchetechniken, Vermeidung von Plagiaten – alles Themen, die zum Kerngeschäft der Bibliothek gehören. Wie verhält man sich als UB? Ist man zufrieden, weil den Studierenden geholfen wird? Ist man froh, dass man sich um diese Themen nicht mehr kümmern muss? Oder versucht man, seine Kompetenz und eine Zusammenarbeit anzubieten?
63

A Conceptual Model of the Revised CAI-NPD-Systems Maturity

Hüsig, Stefan 11 November 2015 (has links)
This article aims to turn the attention of researchers and practitioners in the innovation and engineering management field towards a more fine grained view on the influence of Information Technologies (IT) and New Product Development (NPD) capabilities on innovation outcomes in different stages of maturity. Computer Aided Innovation (CAI), as a specific but often overlooked category of IT-tools for innovation activities, is introduced as having the potential to positively influence the innovation supporting capabilities. Based on current and emerging developments in the fields of CAI and NPD, a revised version of the conceptual model of the CAI-NPD-systems maturity framework is proposed.
64

An Alkali Activated Binder for High Chemical Resistant Self-Leveling Mortar

Funke, Henrik L., Gelbrich, Sandra, Kroll, Lothar 13 October 2016 (has links)
This paper reports the development of an Alkali Activated Binder (AAB) with an emphasis on the performance and the durability of the AAB-matrix. For the development of the matrix, the reactive components granulated slag and coal fly ash were used, which were alkali activated with a mixture of sodium hydroxide (2 - 10 mol/l) and aqueous sodium silicate solution (SiO2/Na2O molar ratio: 2.1) at ambient temperature. A sodium hydroxide concentration of 5.5 mol/l revealed the best compromise between setting time and mechanical strengths of the AAB. With this sodium hydroxide concentration, the compressive and the 3-point bending tensile strength of the hardened AAB were 53.4 and 5.5 MPa respectively after 14 days. As a result of the investigation of the acid resistance, the AAB-matrix showed a very high acid resistance in comparison to ordinary Portland cement concrete. In addition, the AAB had a high frost resistance, which had been validated by the capillary suction, internal damage and freeze thaw test with a relative dynamic E-Modulus of 93% and a total amount of scaled material of 30 g/m2 after 28 freeze-thaw cycles (exposure class: XF3).
65

Senior Dance Experience, Cognitive Performance, and Brain Volume in Older Women

Niemann, Claudia, Godde, Ben, Voelcker-Rehage, Claudia 13 October 2016 (has links)
Physical activity is positively related to cognitive functioning and brain volume in older adults. Interestingly, different types of physical activity vary in their effects on cognition and on the brain. For example, dancing has become an interesting topic in aging research, as it is a popular leisure activity among older adults, involving cardiovascular and motor fitness dimensions that can be positively related to cognition. However, studies on brain structure are missing. In this study, we tested the association of long-term senior dance experience with cognitive performance and gray matter brain volume in older women aged 65 to 82 years. We compared nonprofessional senior dancers (n=28) with nonsedentary control group participants without any dancing experience (n=29), who were similar in age, education, IQ score, lifestyle and health factors, and fitness level. Differences neither in the four tested cognitive domains (executive control, perceptual speed, episodic memory, and long-term memory) nor in brain volume (VBM whole-brain analysis, region-of-interest analysis of the hippocampus) were observed. Results indicate that moderate dancing activity (1-2 times per week, on average) has no additional effects on gray matter volume and cognitive functioning when a certain lifestyle or physical activity and fitness level are reached.
66

Plantar sensory vibration thresholds are not influenced by body position

Germano, Andresa M.C., Schmidt, Daniel, Schlee, Günther, Milani, Thomas L. 25 October 2016 (has links)
Monitoring skin sensitivity is studied to clarify its relationship on balance. Measuring skin sensitivity is performed when subjects are sitting or lying, whereas balance tests are measured during standing. However, afferent signal processing and subsequent efferent responses can be altered by different body positions. Therefore, this study investigated whether vibration perception thresholds (VPTs) are influenced by body positions. Sixty-six healthy subjects (41♀; 25♂) participated in this study. Five measurements of VPTs were performed at each of the three analyzed anatomical locations (heel, first metatarsal head, hallux) of the right plantar foot under two randomized conditions: during sitting and standing. The contact force applied to the probe was measured and controlled within the five trials. Contact forces between the probe and the foot were higher during standing. However, no differences in VPTs were found between conditions. This indicates that VPTs are not different during standing compared to sitting, contrary to our expectations. We conclude that higher forces did not induce increased receptor activity. Since no differences were found between thresholds, future clinical studies can implement plantar VPT tests during sitting in association with balance tests during standing.
67

Exercise-induced changes in basal ganglia volume and their relation to cognitive performance

Becker, Linda, Kutz, D. F., Voelcker-Rehage, Claudia 14 November 2016 (has links)
Physical activity, especially cardiovascular fitness training, has been shown to enhance cognitive performance and to counteract age-related cognitive decline1-5. Furthermore, regular physical activity has been demonstrated to diminish age-related volume-shrinkage in several brain regions particularly in the prefrontal cortex and hippocampus6-10. In the same vein, physical activity and high levels of cardiovascular fitness seem to enhance neurocognition during childhood11-13. In this context, the basal ganglia and its components, the caudate nucleus, the putamen and the globus pallidus, are of special interest as animal research indicates that exercise also seems to influence the molecular architecture and the metabolic capacity of the basal ganglia14,15. Besides their fundamental role in motor execution16, the basal ganglia are also involved in many cognitive functions like mental flexibility17, task-switching ability18 and cognitive control19. Furthermore, age-related disorders like Parkinson’s disease are related to a decline in the dopamine circuits of the basal ganglia20,21. The striatum is the input nucleus of the basal ganglia and is composed of caudate nucleus and putamen. The pars interna of the globus pallidus is (together with the substantia nigra pars reticulata) the output region of the basal ganglia and conveys information from the striatum to the thalamus and back to the frontal areas22. The striatum, which is essential for cognitive flexibility and attentional control, shows an increase during childhood and adolescence23,24 and a particularly rapid and early age-related change9,25 in older adults. Furthermore, the described cognitive functions are essential for academic success of children and young adults. Thus, it is of particular interest to find appropriate interventions that could mitigate both the volume-shrinkage and the (presumably) related cognitive decline in older adults and/or that could support academic success in children. In this review, we will summarize research that investigated whether physical activity has the potential to be such an intervention. First, we will show that neuroplasticity in the basal ganglia is possible in principle. Second, we will report studies where the relationship between physical fitness level and volume of the basal ganglia and its relation to cognitive performance were investigated. Besides cross-sectional studies, we will report studies that investigated exercise-induced changes in the volume of the basal ganglia and related changes in cognitive performance after long-term fitness interventions.
68

Brain circuits underlying visual stability across eye movements—converging evidence for a neuro-computational model of area LIP

Ziesche, Arnold, Hamker, Fred H. January 2014 (has links)
The understanding of the subjective experience of a visually stable world despite the occurrence of an observer's eye movements has been the focus of extensive research for over 20 years. These studies have revealed fundamental mechanisms such as anticipatory receptive field (RF) shifts and the saccadic suppression of stimulus displacements, yet there currently exists no single explanatory framework for these observations. We show that a previously presented neuro-computational model of peri-saccadic mislocalization accounts for the phenomenon of predictive remapping and for the observation of saccadic suppression of displacement (SSD). This converging evidence allows us to identify the potential ingredients of perceptual stability that generalize beyond different data sets in a formal physiology-based model. In particular we propose that predictive remapping stabilizes the visual world across saccades by introducing a feedback loop and, as an emergent result, small displacements of stimuli are not noticed by the visual system. The model provides a link from neural dynamics, to neural mechanism and finally to behavior, and thus offers a testable comprehensive framework of visual stability.
69

Reliability of the calculated maximal lactate steady state in amateur cyclists

Adam, Jennifer, Oehmichen, Matthias, Oehmichen, Eva, Rother, Janine, Müller, Ulrike Maria, Hauser, Thomas, Schulz, Henry 13 July 2015 (has links)
Abstract provided by Publisher Complex performance diagnostics in sports medicine should contain maximal aerobic and maximal anaerobic performance. The requirements on appropriate stress protocols are high. To validate a test protocol quality criteria like objectivity and reliability are necessary. Therefore, the present study was performed in intention to analyze the reliability of maximal lactate production rate (VLamax) by using a sprint test, maximum oxygen consumption (VO2max) by using a ramp test and, based on these data, resulting power in calculated maximum lactate-steady-state (PMLSS) especially for amateur cyclists. All subjects (n=23, age 26 ± 4 years) were leisure cyclists. At three different days they completed first a sprint test to approximate VLamax. After 60 min of recreation time a ramp test to assess VO2max was performed. The results of VLamax-test and VO2max-test and the body weight were used to calculate PMLSS for all subjects. The intra class correlation (ICC) for VLamax and VO2max was 0.904 and 0.987, respectively, coefficient of variation (CV) was 6.3 % and 2.1 %, respectively. Between the measurements the reliable change index of 0.11 mmol∙l-1∙s-1 for VLamax and 3.3 ml∙kg-1∙min-1 for VO2max achieved significance. The mean of the calculated PMLSS was 237 ± 72 W with an RCI of 9 W and reached with ICC = 0.985 a very high reliability. Both metabolic performance tests and the calculated PMLSS are reliable for leisure cyclists.
70

The Impact of Attention on Judgments of Frequency and Duration

Winkler, Isabell, Glauer, Madlen, Betsch, Tilmann, Sedlmeier, Peter 03 June 2015 (has links)
Previous studies that examined human judgments of frequency and duration found an asymmetrical relationship: While frequency judgments were quite accurate and independent of stimulus duration, duration judgments were highly dependent upon stimulus frequency. A potential explanation for these findings is that the asymmetry is moderated by the amount of attention directed to the stimuli. In the current experiment, participants\' attention was manipulated in two ways: (a) intrinsically, by varying the type and arousal potential of the stimuli (names, low-arousal and high-arousal pictures), and (b) extrinsically, by varying the physical effort participants expended during the stimulus presentation (by lifting a dumbbell vs. relaxing the arm). Participants processed stimuli with varying presentation frequencies and durations and were subsequently asked to estimate the frequency and duration of each stimulus. Sensitivity to duration increased for pictures in general, especially when processed under physical effort. A large effect of stimulus frequency on duration judgments was obtained for all experimental conditions, but a similar large effect of presentation duration on frequency judgments emerged only in the conditions that could be expected to draw high amounts of attention to the stimuli: when pictures were judged under high physical effort. Almost no difference in the mutual impact of frequency and duration was obtained for low-arousal or high-arousal pictures. The mechanisms underlying the simultaneous processing of frequency and duration are discussed with respect to existing models derived from animal research. Options for the extension of such models to human processing of frequency and duration are suggested.

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