1,721,036 research outputs found
Au-Seeded Growth of Vertical and in-Plane III-V Nanowires on Graphite Substrates.
No full textGraphene is promising as a transparent, flexible, and possibly cost-effective substrate for nanowire-based devices. We have investigated Au-seeded III-V nanowire growth with graphite as a model substrate. The highest yield of undoped vertical nanowires was found for InAs, but we also observed vertical nanowires for the InP, GaP, and GaAs materials. The yield of vertical nanowires for GaP and GaAs was strongly improved by supplying the p-dopant DEZn before nanowire growth but not by supplying H2S or HCl. In-plane GaAs and GaP nanowire growth exhibited an unexpected behavior, where the seed particles seemingly reflected on the side facets of other nanowires. These results pave the way for vertical and in-plane hybrid graphene- nanowire devices
Preparation and Characterization of Flakes from van der Waals Materials
No full textSpintronika je dynamicky se rozvíjející oblast fyziky pevných látek, která se zaměřuje na fundamentální principy interakce mezi spinem a elektrickým nábojem elektronu. Tyto principy nacházejí uplatnění v celé řadě moderních elektronických zařízení, jako jsou počítače, mobilní telefony, elektromobily, datová a bateriová úložiště, výpočetní centra nebo obnovitelné zdroje energie. V této práci jsme se soustředili na materiál TaRhTe4, v podobě krystalů a exfoliovaných vloček, který je atraktivní pro studium díky přítomnosti Weylova uzlu v blízkosti Fermiho hladiny. Navíc se jedná o Weylův polovodič typu II, který je v přírodě méně běžný. V rámci práce byl zkoumán Hallův jev na objemových vzorcích a byly připraveny tenkovrstvé vzorky ve formě tzv. vloček metodou mechanické exfoliace. Pro zefektivnění výběru vhodných vloček byl vyvinut software, který automaticky vyhledává vzorky s optimální geometrií pro naprašování elektrických kontaktů určených k měření Hallova jevu a dalších elektromagnetických vlastností. Pro vybrané vločky byl navržen design kontaktů a následně realizován pomocí elektronové litografie. V práci jsou prezentovány výsledky měření rezistivity, magnetorezistivity a Hallova jevu při pokojové teplotě i v závislosti na teplotě až do 10 K.Spintronics is a rapidly evolving field of solid-state physics that explores the fundamental interplay between electron spin and charge. These principles have wide-ranging applications in modern technologies, including computers, mobile devices, electric vehicles, data and battery storage, computing centers, and renewable energy systems. In this thesis, we investigate the compound TaRhTe4 both in form of bulk and exfoliated flakes, which is particularly intriguing due to the presence of a Weyl node near the Fermi level. Additionally, TaRhTe4 is a type-II Weyl semimetal, a less common subclass with unique physical properties. Hall effect measurements were performed on bulk samples, and thin flakes were prepared via mechanical exfoliation. To streamline the process of identifying suitable flakes for device fabrication, we developed a software tool that automatically detects flakes with optimal geometry for sputtering electrical contacts. For selected flakes, contact designs were created and implemented using electron beam lithography. The thesis presents experimental results of resistivity, magnetoresistivity, and Hall effect measurements at room temperature as well as across a range of low temperatures down to 10 K
Rtg difrakce a difuzní rozpyl na Heuslerových slitinách
Full text linkRecently, Heusler alloys are studied for their interesting magnetic and electronic properties. These properties are strongly dependent on the crystallographic struc- ture. This work deals with Heusler alloys of the A2BC type. We have powder samples and single-crystaline samples for our study as well. An object of interest was a description of crystallographic structure of the samples, site occupation numbers of each type of atoms and their possible occupation disorder. Pow- der difraction and EXAFS have been measured on the powder samples. Clasical single-crystal diffractions has been meassured on the single-crystaline samples. In the case of a modulated structure in the samples, satelite difractions have been measured too.
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
Passenger requirements for night train carriages
Full text linkEuropa erlebt eine neue Wertschätzung für das Reisen über Nacht auf der Schiene. Steigende Ansprüche an Klimaschutz, der Wunsch nach zeiteffizienten Verbindungen und das Bedürfnis nach Ruhe und Sicherheit lenken Aufmerksamkeit auf Züge, in denen die Reisezeit zur Schlafenszeit wird. Entscheidend für die Akzeptanz des Verkehrsmittels sind nicht nur Fahrzeit und Preis, sondern vor allem das unmittelbare Erlebnis an Bord. Dazu zählen eine gut nutzbare Innenausstattung mit ausreichend Stauraum für Gepäck, bequemen Sitz- und Liegebereichen,stabiler Stromversorgung und Konnektivität sowie Serviceleistungen mit verlässlicher Betreuung und einem geeigneten Verpflegungsangebot.Vor diesem Hintergrund untersucht die Arbeit in Kapitel 2 zuerst die Bedeutung einer bedürfnisgerechten Wagengestaltung anhand einer Literaturrecherche, ordnet die objektiven und subjektiven Determinanten der Verkehrsmittelwahl ein und leitet den theoretischen Rahmen ab. Darauf aufbauend bildet eine Onlinebefragung die Hauptgrundlage der empirischen Untersuchung für die Kapitel 3 und 4. Diese wurde sowohl über Flyer mit QRCodes in Nacht- und Tageszügen als auch digital auf einschlägigen Internetplattformen verbreitet. Insgesamt wurden in einem Zeitraum von August 2024 bis März 2025 1.883 Fragebögen vollständig ausgefüllt. Erfasst wurden in der Umfrage unter anderem soziodemografische Merkmale, soziale Strukturen, Motive der Verkehrsmittelwahl,Reisezwecke und Reisedauern sowie positive und negative Erfahrungen entlang der Reisephase. Ergänzend dazu fand am 03. April 2025 ein moderiertes Fokusgruppengespräch an der Technischen Universität Wien statt. Darin wurden die unterschiedlichen Aspekte der Nachtzugfahrt qualitativ diskutiert und die Erkenntnisse aus der Umfrage erweitert.Die Ergebnisse zeigen, dass die Gestaltung von Nachtzugwagons neben objektive auch subjektive Bedürfnisse der Fahrgäste berücksichtigen muss, da diese maßgeblich zur Wahrnehmung von Komfort und Zufriedenheit beitragen und dadurch die Entscheidung der Verkehrsmittelwahl beeinflussen. Aus den Befragungen geht hervor, dass der Großteil der Nutzerinnen und Nutzer 20- bis 50-jährige Personen sind und mehrheitlich angeben, im Freizeitkontext für eine kurze bis mittlere Dauer zu reisen (bis zu sieben Tage). Die meistgenannten Motive sind Umweltorientierung, Zeitgewinn und der Wunsch nach stressärmeren Reisen. Als häufigste negative Faktoren im Kontext der Schlafqualität und des allgemeinen Reiseerlebnisses im Nachtzug werden starke Bewegungen des Zuges, Geräusche von Mitreisenden und von außen, unbequeme Schlafplätze, fehlender Gepäckstauraum sowie ungünstige Temperatur- und Luftfeuchtigkeitsverhältnisse genannt. Positiv hervorgehoben werden dagegen die empfundene Sicherheit im Zug, sicher verstautes Gepäck, das Reiseerlebnis und das freundliche Zugpersonal. Für zukünftige Nachtzugwagons wird in Kapitel 4.8 eine umfassende Liste an Handlungsempfehlungen für die Elemente der Nachtzugausstattung dargestellt. Die darin enthaltenen Maßnahmen beschreiben die Anforderungen der Befragten an Funktions- und Komfortelemente, technische Elemente sowie Informations- und Serviceelemente.Europe is experiencing a renewed appreciation for overnight rail travel. Growing demands forclimate protection, the desire for efficient connections, and the need for peace and security are drawing attention to trains that allow passengers to sleep while they travel. Decisive factors in the acceptance of this mode of transport include not only travel time and price, but also the actual on-board experience. This includes practical interior design with ample luggage storage,comfortable seating and sleeping areas, a reliable power supply and connectivity, as well as services offering dependable support and a suitable range of catering options.Against this backdrop, Chapter 2 of this thesis first examines the importance of needs-based carriage design through a literature review. It then classifies the objective and subjective determinants of transport mode choice and derives the theoretical framework. Building on this,an online survey forms the basis of the empirical study in Chapters 3 and 4. It was distributed via flyers with QR-codes on night and day trains, as well as digitally on relevant internet platforms. A total of 1,883 questionnaires were completed between August 2024 and March 2025. The survey recorded respondents’ sociodemographic characteristics, social structure,motives for choosing a mode of transport, travel purpose and durations, as well as positive and negative experiences during the journey. Additionally, a moderated focus group discussion washeld at the Vienna University of Technology on 3rd April 2025. This qualitative discussion addressed various aspects of night train travel and expanded on the survey findings.The results indicate that the design of night train carriages should consider both the objectiveand subjective needs of passengers, as these significantly impact their perception of comfortand satisfaction, thus influencing their choice of transport. The surveys show that most users are between 20 and 50 years old and travel for short to medium durations (up to seven days) for leisure purposes. The most frequently cited motives are environmental awareness, time savings and less stressful travel. The most frequently cited negative factors in the context of sleep quality and overall travel experience on night trains are strong train movements, noise from fellow passengers and from outside, uncomfortable sleeping accommodations, lack of luggagestorage facilities, and unfavorable temperature and humidity conditions. On the other hand,perceived safety on the train, securely stowed luggage, travel experience, and friendly train staffare highlighted as positive factors. For future train carriages, Chapter 4.8 presents acomprehensive list of recommendations for action regarding night train equipment. The measures contained therein reflect the respondents’ requirements for functional and comfort elements, technical elements, as well as information and service elements
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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