1,721,014 research outputs found
Quantitative measurement of combustion gases in harsh environments using NDIR spectroscopy.
Full text linkThe global climate change calls for more environmentally friendly use of energy and has led to stricter limits and regulations for the emissions of various greenhouse gases. Consequently, there is nowadays an increasing need for the detection of exhaust and natural gases. This need leads to an ever-growing market for gas sensors, which, at the moment, is dominated by chemical sensors. Yet, the increasing demands to also measure under harsh environmental conditions pave the way for non-invasive measurements and thus optical detection techniques. Here, we present the development of two optical detection systems using non-dispersive infrared absorption spectroscopy (NDIR). One system is intended for civilian use, capable of detecting both CO as well as CO2 in the range of 4–5 µm. Furthermore, restrictions regarding size and economic viability are put on this sensor so it can compete with existing sensors. For CO2, an estimated resolution of 444 ppm is achieved, which is competitive with established sensors on the market. For CO an estimated resolution of 1401 ppm was achieved, rendering it necessary to improve this sensor to be competitive with other available sensors. The second system is used in an exhaust system and is capable of detecting CO2 at 3.2 µm facing cross-sensitivity with H2O. A data analysis method is described to separate the CO2 and H2O signals, revealing a time resolution of 33 µs
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Sachbericht zum Verwendungsnachweis
Full text linkDie Bedeutung von Schnelltests in der (personalisierten) Point-of-Care-Diagnostik nimmt gesellschaftspolitisch immer mehr zu. Das Potenzial dieser Schnelltests liegt zum einen in der einfachen Handhabung, d.h. selbst Personen ohne medizinisch-technische Berufsausbildung können diese benutzen. Zum anderen erzeugen die Schnelltests relativ schnell ein Ergebnis, das als Handlungsbasis für die weitere Behandlung benutzt werden kann. Darüber hinaus können durch die kompakte und kostengünstige Ausführung der dazugehörigen Analysegeräte diese vor Ort eingesetzt werden.
Gesamtziel des qDigiPoC-Verbundes war es nun, innovative Schnelltests mit neuen Produktkonzepten und Funktionalitäten für verschiedene Bereiche, wie Veterinär- und Humanmedizin, Forensik oder Umwelt- und Gefahrstoffanalytik zu entwickeln. Dazu sollten im Verbund Aspekte wie „Erhöhung der Sensitivität“, „Multiplexing“ und „Digitalisierung“ adressiert und Lösungen dazu erarbeitet werden. Ziel des Teilprojektes des Instituts für Nanophotonik Göttingen e.V. war es, die fluoreszenzbasierte Detektion der Lateral Flow Tests (LFTs) zu verbessern und gegebenenfalls neu zu entwickeln. Dazu wurde zum einen in enger Zusammenarbeit mit dem Projektpartner FiSens GmbH ein kompakter Fluoreszenzreader auf Basis der vom Partner entwickelten Faser-Bragg-Spektrometer entwickelt.
Hierbei wurde Wert darauf gelegt, dass der Fluoreszenzreader kompakt bleibt und dabei möglichst den gesamten Wellenlängenbereich von 400 - 1000 nm abdeckt. Darüber hinaus sollte er, anders als marktüblich, nicht nur für ein bestimmtes Fluorophor, sondern für eine Vielzahl von Fluorophoren einsetzbar sein. Um die Sensitivität zu erhöhen wurde auf eine Abtastung und Integration des Gesamtsignals entlang einer Linie hin gearbeitet, mit der eine Ausleserate von über 95 % erzielt werden soll bei einer quantitativen Genauigkeit von 0,1 %. Zum anderen wurde ein Aufbau zur hyperspektralen Fluoreszenzauslesung der LFTs entwickelt, mit der Multiplexing möglich ist. Dazu wurde der LFT auf eine CMOS-Kamera abgebildet und mit Hilfe eines linearen Filters konnte eine Wellenlängenselektion stattfinden. Bei Überlagerung der einzelnen aufgenommenen Bilder konnten so örtlich aufgelöst verschiedene Fluorophore detektiert werden.
Konkret wurden im Teilprojekt folgende Aufgaben adressiert:
- Entwicklung und Optimierung des Designs für ein Fluoreszenz-Reader-System.
- Entwicklung der Auswertealgorithmen zur Trennung verschiedener Fluoreszenzfarbstoffe.
- Entwicklung eines Fluoreszenz-Hyperspektral-Aufbaus.
- Entwicklung eines Konzepts und eines Aufbaus der in der Lehre eingesetzt werden kann.
Das Projekt umfasste also die Entwicklung und Optimierung von Fluoreszenzaufbauten sowie die Algorithmenentwicklung für eine schnelle Analyse der Daten. Am Ende stand ein Funktionsmuster für den Fluoreszenzreader sowie für den hyperspektralen Aufbau zur Verfügung.The importance of rapid tests in (personalized) point-of-care diagnostics is steadily increasing in socio-political terms. The potential of these rapid tests lies, firstly, in their ease of use; even individuals without medical-technical training can operate them. Secondly, the rapid tests produce a result relatively quickly, which can serve as a basis for further treatment. Furthermore, the compact and cost-effective design of the associated analyzers allows for on-site use.
The aim of the sub-project of the Institute for Nanophotonics Göttingen e.V. was to improve and, if necessary, develop new fluorescence-based detection methods for lateral flow tests (LFTs). To this end, a compact fluorescence reader based on the fiber Bragg spectrometer developed by the project partner FiSens GmbH was developed in close collaboration. Emphasis was placed on ensuring that the fluorescence reader remained compact while covering as much of the wavelength range as possible from 400 to 1000 nm. Furthermore, unlike conventional instruments, it should be usable not only for a specific fluorophore, but for a multitude of fluorophores. To increase sensitivity, the aim was to scan and integrate the entire signal along a line, achieving a readout rate of over 95% with a quantitative accuracy of 0.1%. Additionally, a setup for hyperspectral fluorescence readout of the LFTs was developed, enabling multiplexing. For this purpose, the LFT was imaged onto a CMOS camera, and wavelength selection was performed using a linear filter. By superimposing the individual acquired images, different fluorophores could be detected with spatial resolution
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
Ultimate fast switching of semiconductor microcavities: A competition between free carriers
No full textVariations 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
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