Image Retrieval within Augmented Reality

Die vorliegende Arbeit untersucht das Potenzial von Augmented Reality zur Verbesserung von Image Retrieval Prozessen. Herausforderungen in Design und Gebrauchstauglichkeit wurden für beide Forschungsbereiche dargelegt und genutzt, um Designziele für Konzepte zu entwerfen. Eine Taxonomie für Image Retrieval in Augmented Reality wurde basierend auf der Forschungsarbeit entworfen und eingesetzt, um verwandte Arbeiten und generelle Ideen für Interaktionsmöglichkeiten zu strukturieren. Basierend auf der Taxonomie wurden Anwendungsszenarien als weitere Anforderungen für Konzepte formuliert. Mit Hilfe der generellen Ideen und Anforderungen wurden zwei umfassende Konzepte für Image Retrieval in Augmented Reality ausgearbeitet. Eins der Konzepte wurde auf einer Microsoft HoloLens umgesetzt und in einer Nutzerstudie evaluiert. Die Studie zeigt, dass das Konzept grundsätzlich positiv aufgenommen wurde und bietet Erkenntnisse über unterschiedliches Verhalten im Raum und verschiedene Suchstrategien bei der Durchführung von Image Retrieval in der erweiterten Realität.:1 Introduction 1.1 Motivation and Problem Statement 1.1.1 Augmented Reality and Head-Mounted Displays 1.1.2 Image Retrieval 1.1.3 Image Retrieval within Augmented Reality 1.2 Thesis Structure 2 Foundations of Image Retrieval and Augmented Reality 2.1 Foundations of Image Retrieval 2.1.1 Definition of Image Retrieval 2.1.2 Classification of Image Retrieval Systems 2.1.3 Design and Usability in Image Retrieval 2.2 Foundations of Augmented Reality 2.2.1 Definition of Augmented Reality 2.2.2 Augmented Reality Design and Usability 2.3 Taxonomy for Image Retrieval within Augmented Reality 2.3.1 Session Parameters 2.3.2 Interaction Process 2.3.3 Summary of the Taxonomy 3 Concepts for Image Retrieval within Augmented Reality 3.1 Related Work 3.1.1 Natural Query Specification 3.1.2 Situated Result Visualization 3.1.3 3D Result Interaction 3.1.4 Summary of Related Work 3.2 Basic Interaction Concepts for Image Retrieval in Augmented Reality 3.2.1 Natural Query Specification 3.2.2 Situated Result Visualization 3.2.3 3D Result Interaction 3.3 Requirements for Comprehensive Concepts 3.3.1 Design Goals 3.3.2 Application Scenarios 3.4 Comprehensive Concepts 3.4.1 Tangible Query Workbench 3.4.2 Situated Photograph Queries 3.4.3 Conformance of Concept Requirements 4 Prototypic Implementation of Situated Photograph Queries 4.1 Implementation Design 4.1.1 Implementation Process 4.1.2 Structure of the Implementation 4.2 Developer and User Manual 4.2.1 Setup of the Prototype 4.2.2 Usage of the Prototype 4.3 Discussion of the Prototype 5 Evaluation of Prototype and Concept by User Study 5.1 Design of the User Study 5.1.1 Usability Testing 5.1.2 Questionnaire 5.2 Results 5.2.1 Logging of User Behavior 5.2.2 Rating through Likert Scales 5.2.3 Free Text Answers and Remarks during the Study 5.2.4 Observations during the Study 5.2.5 Discussion of Results 6 Conclusion 6.1 Summary of the Present Work 6.2 Outlook on Further WorkThe present work investigates the potential of augmented reality for improving the image retrieval process. Design and usability challenges were identified for both fields of research in order to formulate design goals for the development of concepts. A taxonomy for image retrieval within augmented reality was elaborated based on research work and used to structure related work and basic ideas for interaction. Based on the taxonomy, application scenarios were formulated as further requirements for concepts. Using the basic interaction ideas and the requirements, two comprehensive concepts for image retrieval within augmented reality were elaborated. One of the concepts was implemented using a Microsoft HoloLens and evaluated in a user study. The study showed that the concept was rated generally positive by the users and provided insight in different spatial behavior and search strategies when practicing image retrieval in augmented reality.:1 Introduction 1.1 Motivation and Problem Statement 1.1.1 Augmented Reality and Head-Mounted Displays 1.1.2 Image Retrieval 1.1.3 Image Retrieval within Augmented Reality 1.2 Thesis Structure 2 Foundations of Image Retrieval and Augmented Reality 2.1 Foundations of Image Retrieval 2.1.1 Definition of Image Retrieval 2.1.2 Classification of Image Retrieval Systems 2.1.3 Design and Usability in Image Retrieval 2.2 Foundations of Augmented Reality 2.2.1 Definition of Augmented Reality 2.2.2 Augmented Reality Design and Usability 2.3 Taxonomy for Image Retrieval within Augmented Reality 2.3.1 Session Parameters 2.3.2 Interaction Process 2.3.3 Summary of the Taxonomy 3 Concepts for Image Retrieval within Augmented Reality 3.1 Related Work 3.1.1 Natural Query Specification 3.1.2 Situated Result Visualization 3.1.3 3D Result Interaction 3.1.4 Summary of Related Work 3.2 Basic Interaction Concepts for Image Retrieval in Augmented Reality 3.2.1 Natural Query Specification 3.2.2 Situated Result Visualization 3.2.3 3D Result Interaction 3.3 Requirements for Comprehensive Concepts 3.3.1 Design Goals 3.3.2 Application Scenarios 3.4 Comprehensive Concepts 3.4.1 Tangible Query Workbench 3.4.2 Situated Photograph Queries 3.4.3 Conformance of Concept Requirements 4 Prototypic Implementation of Situated Photograph Queries 4.1 Implementation Design 4.1.1 Implementation Process 4.1.2 Structure of the Implementation 4.2 Developer and User Manual 4.2.1 Setup of the Prototype 4.2.2 Usage of the Prototype 4.3 Discussion of the Prototype 5 Evaluation of Prototype and Concept by User Study 5.1 Design of the User Study 5.1.1 Usability Testing 5.1.2 Questionnaire 5.2 Results 5.2.1 Logging of User Behavior 5.2.2 Rating through Likert Scales 5.2.3 Free Text Answers and Remarks during the Study 5.2.4 Observations during the Study 5.2.5 Discussion of Results 6 Conclusion 6.1 Summary of the Present Work 6.2 Outlook on Further Wor

Visual ratings of atrophy in MCI: prediction of conversion and relationship with CSF biomarkers.

Medial temporal lobe atrophy (MTA) and cerebrospinal fluid (CSF) markers of Alzheimer's disease (AD) pathology may aid the early detection of AD in mild cognitive impairment (MCI). However, the relationship between structural and pathological markers is not well understood. Furthermore, while posterior atrophy (PA) is well recognized in AD, its value in predicting conversion from late-onset amnestic MCI to AD is unclear. In this study we used visual ratings of MTA and PA to assess their value in predicting conversion to AD in 394 MCI patients. The relationship of atrophy patterns with CSF Aβ1-42, tau, and p-tau(181) was further investigated in 114 controls, 192 MCI, and 99 AD patients. There was a strong association of MTA ratings with conversion to AD (p < 0.001), with a weaker association for PA ratings (p = 0.047). Specific associations between visual ratings and CSF biomarkers were found; MTA was associated with lower levels of Aβ1-42 in MCI, while PA was associated with elevated levels of tau in MCI and AD, which may reflect widespread neuronal loss including posterior regions. These findings suggest both that posterior atrophy may predict conversion to AD in late-onset MCI, and that there may be differential relationships between CSF biomarkers and regional atrophy patterns

Presymptomatic cortical thinning in familial Alzheimer disease: A longitudinal MRI study.

OBJECTIVE: To identify a cortical signature pattern of cortical thinning in familial Alzheimer disease (FAD) and assess its utility in detecting and tracking presymptomatic neurodegeneration. METHODS: We recruited 43 FAD mutation carriers-36 PSEN1, 7 APP (20 symptomatic, 23 presymptomatic)-and 42 healthy controls to a longitudinal clinical and MRI study. T1-weighted MRI scans were acquired at baseline in all participants; 55 individuals (33 mutation carriers; 22 controls) had multiple (mean 2.9) follow-up scans approximately annually. Cortical thickness was measured using FreeSurfer. A cortical thinning signature was identified from symptomatic FAD participants. We then examined cortical thickness changes in this signature region in presymptomatic carriers and assessed associations with cognitive performance. RESULTS: The cortical signature included 6 regions: entorhinal cortex, inferior parietal cortex, precuneus, superior parietal cortex, superior frontal cortex, and supramarginal gyrus. There were significant differences in mean cortical signature thickness between mutation carriers and controls 3 years before predicted symptom onset. The earliest significant difference in a single region, detectable 4 years preonset, was in the precuneus. Rate of change in cortical thickness became significantly different in the cortical signature at 5 years before predicted onset, and in the precuneus at 8 years preonset. Baseline mean signature thickness predicted rate of subsequent thinning and correlated with presymptomatic cognitive change. CONCLUSIONS: The FAD cortical signature appears to be similar to that described for sporadic AD. All component regions showed significant presymptomatic thinning. A composite signature may provide more robust results than a single region and have utility as an outcome measure in presymptomatic trials

Consensus classification of posterior cortical atrophy

INTRODUCTION: A classification framework for posterior cortical atrophy (PCA) is proposed to improve the uniformity of definition of the syndrome in a variety of research settings. METHODS: Consensus statements about PCA were developed through a detailed literature review, the formation of an international multidisciplinary working party which convened on four occasions, and a Web-based quantitative survey regarding symptom frequency and the conceptualization of PCA. RESULTS: A three-level classification framework for PCA is described comprising both syndrome- and disease-level descriptions. Classification level 1 (PCA) defines the core clinical, cognitive, and neuroimaging features and exclusion criteria of the clinico-radiological syndrome. Classification level 2 (PCA-pure, PCA-plus) establishes whether, in addition to the core PCA syndrome, the core features of any other neurodegenerative syndromes are present. Classification level 3 (PCA attributable to AD [PCA-AD], Lewy body disease [PCA-LBD], corticobasal degeneration [PCA-CBD], prion disease [PCA-prion]) provides a more formal determination of the underlying cause of the PCA syndrome, based on available pathophysiological biomarker evidence. The issue of additional syndrome-level descriptors is discussed in relation to the challenges of defining stages of syndrome severity and characterizing phenotypic heterogeneity within the PCA spectrum. DISCUSSION: There was strong agreement regarding the definition of the core clinico-radiological syndrome, meaning that the current consensus statement should be regarded as a refinement, development, and extension of previous single-center PCA criteria rather than any wholesale alteration or redescription of the syndrome. The framework and terminology may facilitate the interpretation of research data across studies, be applicable across a broad range of research scenarios (e.g., behavioral interventions, pharmacological trials), and provide a foundation for future collaborative work

Identification of additional risk loci for stroke and small vessel disease: a meta-analysis of genome-wide association studies

BACKGROUND: Genetic determinants of stroke, the leading neurological cause of death and disability, are poorly understood and have seldom been explored in the general population. Our aim was to identify additional loci for stroke by doing a meta-analysis of genome-wide association studies. METHODS: For the discovery sample, we did a genome-wide analysis of common genetic variants associated with incident stroke risk in 18 population-based cohorts comprising 84 961 participants, of whom 4348 had stroke. Stroke diagnosis was ascertained and validated by the study investigators. Mean age at stroke ranged from 45·8 years to 76·4 years, and data collection in the studies took place between 1948 and 2013. We did validation analyses for variants yielding a significant association (at p<5 × 10(-6)) with all-stroke, ischaemic stroke, cardioembolic ischaemic stroke, or non-cardioembolic ischaemic stroke in the largest available cross-sectional studies (70 804 participants, of whom 19 816 had stroke). Summary-level results of discovery and follow-up stages were combined using inverse-variance weighted fixed-effects meta-analysis, and in-silico lookups were done in stroke subtypes. For genome-wide significant findings (at p<5 × 10(-8)), we explored associations with additional cerebrovascular phenotypes and did functional experiments using conditional (inducible) deletion of the probable causal gene in mice. We also studied the expression of orthologs of this probable causal gene and its effects on cerebral vasculature in zebrafish mutants. FINDINGS: We replicated seven of eight known loci associated with risk for ischaemic stroke, and identified a novel locus at chromosome 6p25 (rs12204590, near FOXF2) associated with risk of all-stroke (odds ratio [OR] 1·08, 95% CI 1·05-1·12, p=1·48 × 10(-8); minor allele frequency 21%). The rs12204590 stroke risk allele was also associated with increased MRI-defined burden of white matter hyperintensity-a marker of cerebral small vessel disease-in stroke-free adults (n=21 079; p=0·0025). Consistently, young patients (aged 2-32 years) with segmental deletions of FOXF2 showed an extensive burden of white matter hyperintensity. Deletion of Foxf2 in adult mice resulted in cerebral infarction, reactive gliosis, and microhaemorrhage. The orthologs of FOXF2 in zebrafish (foxf2b and foxf2a) are expressed in brain pericytes and mutant foxf2b(-/-) cerebral vessels show decreased smooth muscle cell and pericyte coverage. INTERPRETATION: We identified common variants near FOXF2 that are associated with increased stroke susceptibility. Epidemiological and experimental data suggest that FOXF2 mediates this association, potentially via differentiation defects of cerebral vascular mural cells. Further expression studies in appropriate human tissues, and further functional experiments with long follow-up periods are needed to fully understand the underlying mechanisms

Image Retrieval within Augmented Reality

Die vorliegende Arbeit untersucht das Potenzial von Augmented Reality zur Verbesserung von Image Retrieval Prozessen. Herausforderungen in Design und Gebrauchstauglichkeit wurden für beide Forschungsbereiche dargelegt und genutzt, um Designziele für Konzepte zu entwerfen. Eine Taxonomie für Image Retrieval in Augmented Reality wurde basierend auf der Forschungsarbeit entworfen und eingesetzt, um verwandte Arbeiten und generelle Ideen für Interaktionsmöglichkeiten zu strukturieren. Basierend auf der Taxonomie wurden Anwendungsszenarien als weitere Anforderungen für Konzepte formuliert. Mit Hilfe der generellen Ideen und Anforderungen wurden zwei umfassende Konzepte für Image Retrieval in Augmented Reality ausgearbeitet. Eins der Konzepte wurde auf einer Microsoft HoloLens umgesetzt und in einer Nutzerstudie evaluiert. Die Studie zeigt, dass das Konzept grundsätzlich positiv aufgenommen wurde und bietet Erkenntnisse über unterschiedliches Verhalten im Raum und verschiedene Suchstrategien bei der Durchführung von Image Retrieval in der erweiterten Realität.:1 Introduction 1.1 Motivation and Problem Statement 1.1.1 Augmented Reality and Head-Mounted Displays 1.1.2 Image Retrieval 1.1.3 Image Retrieval within Augmented Reality 1.2 Thesis Structure 2 Foundations of Image Retrieval and Augmented Reality 2.1 Foundations of Image Retrieval 2.1.1 Definition of Image Retrieval 2.1.2 Classification of Image Retrieval Systems 2.1.3 Design and Usability in Image Retrieval 2.2 Foundations of Augmented Reality 2.2.1 Definition of Augmented Reality 2.2.2 Augmented Reality Design and Usability 2.3 Taxonomy for Image Retrieval within Augmented Reality 2.3.1 Session Parameters 2.3.2 Interaction Process 2.3.3 Summary of the Taxonomy 3 Concepts for Image Retrieval within Augmented Reality 3.1 Related Work 3.1.1 Natural Query Specification 3.1.2 Situated Result Visualization 3.1.3 3D Result Interaction 3.1.4 Summary of Related Work 3.2 Basic Interaction Concepts for Image Retrieval in Augmented Reality 3.2.1 Natural Query Specification 3.2.2 Situated Result Visualization 3.2.3 3D Result Interaction 3.3 Requirements for Comprehensive Concepts 3.3.1 Design Goals 3.3.2 Application Scenarios 3.4 Comprehensive Concepts 3.4.1 Tangible Query Workbench 3.4.2 Situated Photograph Queries 3.4.3 Conformance of Concept Requirements 4 Prototypic Implementation of Situated Photograph Queries 4.1 Implementation Design 4.1.1 Implementation Process 4.1.2 Structure of the Implementation 4.2 Developer and User Manual 4.2.1 Setup of the Prototype 4.2.2 Usage of the Prototype 4.3 Discussion of the Prototype 5 Evaluation of Prototype and Concept by User Study 5.1 Design of the User Study 5.1.1 Usability Testing 5.1.2 Questionnaire 5.2 Results 5.2.1 Logging of User Behavior 5.2.2 Rating through Likert Scales 5.2.3 Free Text Answers and Remarks during the Study 5.2.4 Observations during the Study 5.2.5 Discussion of Results 6 Conclusion 6.1 Summary of the Present Work 6.2 Outlook on Further WorkThe present work investigates the potential of augmented reality for improving the image retrieval process. Design and usability challenges were identified for both fields of research in order to formulate design goals for the development of concepts. A taxonomy for image retrieval within augmented reality was elaborated based on research work and used to structure related work and basic ideas for interaction. Based on the taxonomy, application scenarios were formulated as further requirements for concepts. Using the basic interaction ideas and the requirements, two comprehensive concepts for image retrieval within augmented reality were elaborated. One of the concepts was implemented using a Microsoft HoloLens and evaluated in a user study. The study showed that the concept was rated generally positive by the users and provided insight in different spatial behavior and search strategies when practicing image retrieval in augmented reality.:1 Introduction 1.1 Motivation and Problem Statement 1.1.1 Augmented Reality and Head-Mounted Displays 1.1.2 Image Retrieval 1.1.3 Image Retrieval within Augmented Reality 1.2 Thesis Structure 2 Foundations of Image Retrieval and Augmented Reality 2.1 Foundations of Image Retrieval 2.1.1 Definition of Image Retrieval 2.1.2 Classification of Image Retrieval Systems 2.1.3 Design and Usability in Image Retrieval 2.2 Foundations of Augmented Reality 2.2.1 Definition of Augmented Reality 2.2.2 Augmented Reality Design and Usability 2.3 Taxonomy for Image Retrieval within Augmented Reality 2.3.1 Session Parameters 2.3.2 Interaction Process 2.3.3 Summary of the Taxonomy 3 Concepts for Image Retrieval within Augmented Reality 3.1 Related Work 3.1.1 Natural Query Specification 3.1.2 Situated Result Visualization 3.1.3 3D Result Interaction 3.1.4 Summary of Related Work 3.2 Basic Interaction Concepts for Image Retrieval in Augmented Reality 3.2.1 Natural Query Specification 3.2.2 Situated Result Visualization 3.2.3 3D Result Interaction 3.3 Requirements for Comprehensive Concepts 3.3.1 Design Goals 3.3.2 Application Scenarios 3.4 Comprehensive Concepts 3.4.1 Tangible Query Workbench 3.4.2 Situated Photograph Queries 3.4.3 Conformance of Concept Requirements 4 Prototypic Implementation of Situated Photograph Queries 4.1 Implementation Design 4.1.1 Implementation Process 4.1.2 Structure of the Implementation 4.2 Developer and User Manual 4.2.1 Setup of the Prototype 4.2.2 Usage of the Prototype 4.3 Discussion of the Prototype 5 Evaluation of Prototype and Concept by User Study 5.1 Design of the User Study 5.1.1 Usability Testing 5.1.2 Questionnaire 5.2 Results 5.2.1 Logging of User Behavior 5.2.2 Rating through Likert Scales 5.2.3 Free Text Answers and Remarks during the Study 5.2.4 Observations during the Study 5.2.5 Discussion of Results 6 Conclusion 6.1 Summary of the Present Work 6.2 Outlook on Further Wor

Image Retrieval within Augmented Reality

Die vorliegende Arbeit untersucht das Potenzial von Augmented Reality zur Verbesserung von Image Retrieval Prozessen. Herausforderungen in Design und Gebrauchstauglichkeit wurden für beide Forschungsbereiche dargelegt und genutzt, um Designziele für Konzepte zu entwerfen. Eine Taxonomie für Image Retrieval in Augmented Reality wurde basierend auf der Forschungsarbeit entworfen und eingesetzt, um verwandte Arbeiten und generelle Ideen für Interaktionsmöglichkeiten zu strukturieren. Basierend auf der Taxonomie wurden Anwendungsszenarien als weitere Anforderungen für Konzepte formuliert. Mit Hilfe der generellen Ideen und Anforderungen wurden zwei umfassende Konzepte für Image Retrieval in Augmented Reality ausgearbeitet. Eins der Konzepte wurde auf einer Microsoft HoloLens umgesetzt und in einer Nutzerstudie evaluiert. Die Studie zeigt, dass das Konzept grundsätzlich positiv aufgenommen wurde und bietet Erkenntnisse über unterschiedliches Verhalten im Raum und verschiedene Suchstrategien bei der Durchführung von Image Retrieval in der erweiterten Realität.:1 Introduction 1.1 Motivation and Problem Statement 1.1.1 Augmented Reality and Head-Mounted Displays 1.1.2 Image Retrieval 1.1.3 Image Retrieval within Augmented Reality 1.2 Thesis Structure 2 Foundations of Image Retrieval and Augmented Reality 2.1 Foundations of Image Retrieval 2.1.1 Definition of Image Retrieval 2.1.2 Classification of Image Retrieval Systems 2.1.3 Design and Usability in Image Retrieval 2.2 Foundations of Augmented Reality 2.2.1 Definition of Augmented Reality 2.2.2 Augmented Reality Design and Usability 2.3 Taxonomy for Image Retrieval within Augmented Reality 2.3.1 Session Parameters 2.3.2 Interaction Process 2.3.3 Summary of the Taxonomy 3 Concepts for Image Retrieval within Augmented Reality 3.1 Related Work 3.1.1 Natural Query Specification 3.1.2 Situated Result Visualization 3.1.3 3D Result Interaction 3.1.4 Summary of Related Work 3.2 Basic Interaction Concepts for Image Retrieval in Augmented Reality 3.2.1 Natural Query Specification 3.2.2 Situated Result Visualization 3.2.3 3D Result Interaction 3.3 Requirements for Comprehensive Concepts 3.3.1 Design Goals 3.3.2 Application Scenarios 3.4 Comprehensive Concepts 3.4.1 Tangible Query Workbench 3.4.2 Situated Photograph Queries 3.4.3 Conformance of Concept Requirements 4 Prototypic Implementation of Situated Photograph Queries 4.1 Implementation Design 4.1.1 Implementation Process 4.1.2 Structure of the Implementation 4.2 Developer and User Manual 4.2.1 Setup of the Prototype 4.2.2 Usage of the Prototype 4.3 Discussion of the Prototype 5 Evaluation of Prototype and Concept by User Study 5.1 Design of the User Study 5.1.1 Usability Testing 5.1.2 Questionnaire 5.2 Results 5.2.1 Logging of User Behavior 5.2.2 Rating through Likert Scales 5.2.3 Free Text Answers and Remarks during the Study 5.2.4 Observations during the Study 5.2.5 Discussion of Results 6 Conclusion 6.1 Summary of the Present Work 6.2 Outlook on Further WorkThe present work investigates the potential of augmented reality for improving the image retrieval process. Design and usability challenges were identified for both fields of research in order to formulate design goals for the development of concepts. A taxonomy for image retrieval within augmented reality was elaborated based on research work and used to structure related work and basic ideas for interaction. Based on the taxonomy, application scenarios were formulated as further requirements for concepts. Using the basic interaction ideas and the requirements, two comprehensive concepts for image retrieval within augmented reality were elaborated. One of the concepts was implemented using a Microsoft HoloLens and evaluated in a user study. The study showed that the concept was rated generally positive by the users and provided insight in different spatial behavior and search strategies when practicing image retrieval in augmented reality.:1 Introduction 1.1 Motivation and Problem Statement 1.1.1 Augmented Reality and Head-Mounted Displays 1.1.2 Image Retrieval 1.1.3 Image Retrieval within Augmented Reality 1.2 Thesis Structure 2 Foundations of Image Retrieval and Augmented Reality 2.1 Foundations of Image Retrieval 2.1.1 Definition of Image Retrieval 2.1.2 Classification of Image Retrieval Systems 2.1.3 Design and Usability in Image Retrieval 2.2 Foundations of Augmented Reality 2.2.1 Definition of Augmented Reality 2.2.2 Augmented Reality Design and Usability 2.3 Taxonomy for Image Retrieval within Augmented Reality 2.3.1 Session Parameters 2.3.2 Interaction Process 2.3.3 Summary of the Taxonomy 3 Concepts for Image Retrieval within Augmented Reality 3.1 Related Work 3.1.1 Natural Query Specification 3.1.2 Situated Result Visualization 3.1.3 3D Result Interaction 3.1.4 Summary of Related Work 3.2 Basic Interaction Concepts for Image Retrieval in Augmented Reality 3.2.1 Natural Query Specification 3.2.2 Situated Result Visualization 3.2.3 3D Result Interaction 3.3 Requirements for Comprehensive Concepts 3.3.1 Design Goals 3.3.2 Application Scenarios 3.4 Comprehensive Concepts 3.4.1 Tangible Query Workbench 3.4.2 Situated Photograph Queries 3.4.3 Conformance of Concept Requirements 4 Prototypic Implementation of Situated Photograph Queries 4.1 Implementation Design 4.1.1 Implementation Process 4.1.2 Structure of the Implementation 4.2 Developer and User Manual 4.2.1 Setup of the Prototype 4.2.2 Usage of the Prototype 4.3 Discussion of the Prototype 5 Evaluation of Prototype and Concept by User Study 5.1 Design of the User Study 5.1.1 Usability Testing 5.1.2 Questionnaire 5.2 Results 5.2.1 Logging of User Behavior 5.2.2 Rating through Likert Scales 5.2.3 Free Text Answers and Remarks during the Study 5.2.4 Observations during the Study 5.2.5 Discussion of Results 6 Conclusion 6.1 Summary of the Present Work 6.2 Outlook on Further Wor

Student Activism Remains a Potent Force Worldwide

Student activism remains a potent force worldwide. Recently, students were instrumental in the collapse of the regime in Ukraine, and were key forces in the Arab Spring movements. Students, however, are unable to ensure that their views will be reflected in the governments that emerge from unrest. Students also are active participants in campus events, and have often been instrumental in shaping higher education policy

Stomach contents of the archaeocete Basilosaurus isis: Apex predator in oceans of the late Eocene.

Apex predators live at the top of an ecological pyramid, preying on animals in the pyramid below and normally immune from predation themselves. Apex predators are often, but not always, the largest animals of their kind. The living killer whale Orcinus orca is an apex predator in modern world oceans. Here we focus on an earlier apex predator, the late Eocene archaeocete Basilosaurus isis from Wadi Al Hitan in Egypt, and show from stomach contents that it fed on smaller whales (juvenile Dorudon atrox) and large fishes (Pycnodus mokattamensis). Our observations, the first direct evidence of diet in Basilosaurus isis, confirm a predator-prey relationship of the two most frequently found fossil whales in Wadi Al-Hitan, B. isis and D. atrox. This extends our understanding of their paleoecology. Late Eocene Basilosaurus isis, late Miocene Livyatan melvillei, and modern Orcinus orca are three marine apex predators known from relatively short intervals of time. Little is known about whales as apex predators through much of the Cenozoic era, and whales as apex predators deserve more attention than they have received