1,721,333 research outputs found
Anatomical and microstructural imaging of angiogenesis
No full textThis article reviews and discusses different options for visualizing the microarchitecture of vessels ex vivo and in vivo with respect to reliability, practicability and availability. The investigation of angiogenesis by standard histological methods, like microvessel density counts, is limited since the three-dimensional (3-D) architecture and the functionality of vessels cannot be considered properly. Coregistration of immunostained images of vessels may be performed but is time consuming and often not sufficiently accurate. Confocal fluorescence microscopy is an alternative, but only enables 3-D stacks of less than 500 nm in thickness. Multiphoton microscopy and other advanced technologies, such as optical coherence tomography and optical frequency domain imaging, provide a deeper view into tissues and allow for in vivo imaging of microvessels, which is a precondition for longitudinal studies. Besides these microscopic techniques, the vascularization in larger tissue samples can be investigated using corrosion casts in combination with scanning electron microscopy, or microcomputed tomography (A mu CT). Furthermore, recent improvements in A mu CT technology open up new perspectives for in vivo scans with high resolution and tolerable X-ray doses. Also 3-D contrast-enhanced high-frequency ultrasound has been shown to be sensitive for angiogenic vessels and even distinguishing between mature and immature vessels appears feasible. Microvessel architecture can also be visualized by MRI. Here, T1-weighted angiography techniques after injection of blood pool contrast agents appear preferable. Optoacoustic tomographic imaging has more recently shown promise for high-resolution in vivo mapping of the microvasculature in rodents using intrinsic haemoglobin-based contrast and exogenous contrast agents
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Skalierbare Bildgebung lichtstreuender Organismen mit hybrider Lichtblattmikroskopie und optoakustischer Tomographie
No full textBiomedical imaging plays a key role in the advancement of medical research. While high-resolution microscopy enables the harvest of molecular and cellular information, a holistic picture on organ level can only be provided by means of macroscopic imaging. Wedged in between Micro-macro, the mesoscopic regime offers important bridging of the information transfer. The focus of the research presented in this thesis centers around the application of selective plane illumination microscopy (SPIM) and its collaborative potential with optoacoustic tomography (OAT) in the mesoscopic regime.Die biomedizinische Bildgebung leistet einen Schlüsselbeitrag zum Fortschritt in der medizinischen Forschung. Am einen Ende des Spektrums kann die hochauflösende Mikroskopie Informationen auf zellulärer und molekularer Ebene liefern, aber am anderen Ende kann nur die makroskopische Bildgebung den Kontext dieser Informationen im Organ oder im ganzen Körper herstellen. Das zwischen diesen beiden Bereichen angesiedelte mesoskopische Regime kann eine wichtige Brücke zur Verknüpfung dieser beiden komplementären Informationen schlagen. Der Fokus der vorgestellten Arbeit liegt auf der Anwendung der Lichtblattmikroskopie und auf deren vorteilhaften Kombination mit der optoakustischen Tomographie (OAT) im mesoskopischen Regime
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Entwicklung der Hybriden Optoakustischen Tomographie, Puls-Echo und Transmission Ultraschall Sonographie
Full text linkThe unique advantage of ultrasound waves to interrogate biological tissues has been exploited in multiple imaging technologies providing otherwise unattainable information on structure and function of living organisms. Richer contrast can be achieved by using light, instead of sound, to generate ultrasound waves within biological tissues. Based on this principle, multispectral optoacoustic tomography has revolutionized biomedical research and is undergoing rapid clinical translation. Combination of US-based imaging approaches into a single multi-modal platform can complement and enhance the advantages of the stand-alone modalities. This work is dedicated to development of instrumentation and algorithms for the first hybrid optoacoustic, reflection (RUCT) and transmission (TUCT) ultrasound computed tomography system in the context of pre-clinical small animal imaging as well as translational research.Die Verwendung von Ultraschallwellen zur Evaluierung von biologischem Gewebe weist den einzigartigen Vorteil auf, dass ansonsten unzugängliche Informationen verfügbar werden. Diese herausragende Eigenschaft wurde bereits in verschiedensten Bildgebungsmodalitäten ausgenutzt um Strukturen und Funktionen von lebenden Organismen sichtbar zu machen. Ein stärkerer Kontrast kann hierbei durch die Verwendung von Licht anstelle von Schall zur Erzeugung von Ultraschallwellen in biologischem Gewebe erreicht werden. Basierend auf diesem Prinzip hat die multispektrale optoakustische Tomografie die biomedizinische Forschung bereits revolutioniert und ist auf dem Vormarsch im Bereich der klinischen Translation. Die Kombination mehrerer Ultraschall-basierender Bildgebungsverfahren zu einer einzigen multimodalen Plattform kann die Vorteile der einzelnen eigenständigen Modalitäten weiter komplementieren und verstärken. Ziel dieser Arbeit ist deshalb die Entwicklung von Instrumenten und Algorithmen zur Generierung des ersten hybriden optoakustischen Reflektions- (RUCT) und Transmissions- (TUCT) Ultraschall-Computertomografiesystems für den Einsatz in der präklinischen Kleintierbildgebung sowie der translationalen Forschung
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