278 research outputs found
Separating spin and charge transport in single wall carbon nanotubes
We demonstrate spin injection and detection in single wall carbon nanotubes
using a 4-terminal, non-local geometry. This measurement geometry completely
separates the charge and spin circuits. Hence all spurious magnetoresistance
effects are eliminated and the measured signal is due to spin accumulation
only. Combining our results with a theoretical model, we deduce a spin
polarization at the contacts of approximately 25 %. We show that the
magnetoresistance changes measured in the conventional two-terminal geometry
are dominated by effects not related to spin accumulation.Comment: Number of pages: 11 Number of figures:
The Magneto-coulomb effect in spin valve devices
We discuss the influence of the magneto-coulomb effect (MCE) on the
magnetoconductance of spin valve devices. We show that MCE can induce
magnetoconductances of several per cents or more, dependent on the strength of
the coulomb blockade. Furthermore, the MCE-induced magnetoconductance changes
sign as a function of gate voltage. We emphasize the importance of separating
conductance changes induced by MCE from those due to spin accumulation in spin
valve devices.Comment: This paper includes 3 figure
Generating indicative-informative summaries with SumUM
We present and evaluate SumUM, a text summarization system that takes a raw technical text as input and produces an indicative informative summary. The indicative part of the summary identifies the topics of the document, and the informative part elaborates on some of these topics according to the reader's interest. SumUM motivates the topics, describes entities, and defines concepts. It is a first step for exploring the issue of dynamic summarization. This is accomplished through a process of shallow syntactic and semantic analysis, concept identification, and text regeneration. Our method was developed through the study of a corpus of abstracts written by professional abstractors. Relying on human judgment, we have evaluated indicativeness, informativeness, and text acceptability of the automatic summaries. The results thus far indicate good performance when compared with other summarization technologies
Enhancing Student Learning, Engagement, and Employment Through Inclusive Curriculum Design
The diverse student body at Queen Mary University of London requires an effective approach to ensure equal opportunity in higher education. This includes promoting equality, inclusion, equity, and access to services. To address this, the authors present a case study about a redesigned cloud computing module to enhance student engagement, employability, and intercultural learning. The module's learning outcomes are based on the students' graduate attributes and cross-disciplinary abilities, as defined by professional frameworks. To support equal opportunity and facilitate multicultural growth, they have updated the education and learning model to include innovative teaching methods and materials for efficient curriculum delivery. This study establishes the foundation for an action research review of cloud computing that aims to create an inclusive curriculum
A transfer technique for high mobility graphene devices on commercially available hexagonal boron nitride
We present electronic transport measurements of single- and bilayer graphene
on commercially available hexagonal boron nitride. We extract mobilities as
high as 125 000 cm^2/V/s at room temperature and 275 000 cm^2/V/s at 4.2 K. The
excellent quality is supported by the early development of the nu = 1 quantum
Hall plateau at a magnetic field of 5 T and temperature of 4.2 K. We also
present a new and accurate transfer technique of graphene to hexagonal boron
nitride crystals. This technique is simple, fast and yields atomically flat
graphene on boron nitride which is almost completely free of bubbles or
wrinkles. The potential of commercially available boron nitride combined with
our transfer technique makes high mobility graphene devices more accessible.Comment: 3 pages, 3 figure
Modelling the response of phytoplankton in a shallow lake (Loch Leven, UK) to changes in lake retention time and water temperature.
The phytoplankton community of Loch Leven in 2005 was modelled and subjected to a combination of different flushing rates and water temperatures in order to assess the lake’s sensitivity to these two climatic drivers. Whilst the simulated annual mean total chlorophyll a proved relatively insensitive to these changes, at the species level marked changes were recorded. Some species responded positively to increased temperature (e.g. Aulacoseira), some negatively (e.g. Asterionella), whilst others were negatively affected by increased flow (e.g. Aphanocapsa) and others enhanced (e.g. Stephanodiscus). However, this relationship with flow was season dependent with, for example, a simulated increase in summer inflows actually benefiting some species through increased nutrient supply, whereas an equivalent increase in flow in wetter seasons would have negatively affected those species (i.e. through flushing loss). Overall, the simulations showed that the range of species types simulated in the community was sufficient for one species to always benefit from the changing niches created by the multiple climatic drivers applied in this study. The level of exploitation by such a species was only constrained by the nutrient carrying capacity of the system, which led to the overall dampened response in the total chlorophyll a measure, both at the annual and season scale. Thus, whilst overall biomass showed relatively little reaction to the two climatic drivers tested, the phytoplankton community composition responded markedly
Factors Affecting Web Page Similarity
Abstract. Tools that allow effective information organisation, access and navigation are becoming increasingly important on the Web. Sim-ilarity between web pages is a concept that is central to such tools. In this paper, we examine the effect that content and layout-related as-pects of web pages have on web page similarity. We consider the textual content contained within common HTML tags, the structural layout of pages, and the query terms contained within pages. Our study shows that combinations of factors can yield more promising results than individual factors, and that different aspects of web pages affect similarities between pages in a different manner. We found a number of factors that, when taken into account, can result in effective measures of similarity between web pages. Query information in particular, proved to be important for the effective organisation of web pages.
Giant Nonlocality near the Dirac Point in Graphene
Transport measurements have been a powerful tool for uncovering new
electronic phenomena in graphene. We report nonlocal measurements performed in
the Hall bar geometry with voltage probes far away from the classical path of
charge flow. We observe a large nonlocal response near the Dirac point in
fields as low as 0.1T, which persists up to room temperature. The nonlocality
is consistent with the long-range flavor currents induced by lifting of
spin/valley degeneracy. The effect is expected to contribute strongly to all
magnetotransport phenomena near the neutrality point
Anisotropic spin relaxation in graphene
Spin relaxation in graphene is investigated in electrical graphene spin valve
devices in the non-local geometry. Ferromagnetic electrodes with in-plane
magnetizations inject spins parallel to the graphene layer. They are subject to
Hanle spin precession under a magnetic field applied perpendicular to the
graphene layer. Fields above 1.5 T force the magnetization direction of the
ferromagnetic contacts to align to the field, allowing injection of spins
perpendicular to the graphene plane. A comparison of the spin signals at B = 0
and B = 2 T shows a 20 % decrease in spin relaxation time for spins
perpendicular to the graphene layer compared to spins parallel to the layer. We
analyze the results in terms of the different strengths of the spin orbit
effective fields in the in-plane and out-of-plane directions.Comment: 5 pages, 4 figure
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