13,101 research outputs found
Transthyretin familial amyloid polyneuropathy impact on health-related quality of life
info:eu-repo/semantics/publishedVersio
Graphene-based spin-pumping transistor
We demonstrate with a fully quantum-mechanical approach that graphene can
function as gate-controllable transistors for pumped spin currents, i.e., a
stream of angular momentum induced by the precession of adjacent
magnetizations, which exists in the absence of net charge currents.
Furthermore, we propose as a proof of concept how these spin currents can be
modulated by an electrostatic gate. Because our proposal involves nano-sized
systems that function with very high speeds and in the absence of any applied
bias, it is potentially useful for the development of transistors capable of
combining large processing speeds, enhanced integration and extremely low power
consumption
Graphene as a non-magnetic spin-current lens
In spintronics, the ability to transport magnetic information often depends
on the existence of a spin current traveling between two different magnetic
objects acting as source and probe. A large fraction of this information never
reaches the probe and is lost because the spin current tends to travel
omni-directionally. We propose that a curved boundary between a gated and a
non-gated region within graphene acts as an ideal lens for spin currents
despite being entirely of non-magnetic nature. We show as a proof of concept
that such lenses can be utilized to redirect the spin current that travels away
from a source onto a focus region where a magnetic probe is located, saving a
considerable fraction of the magnetic information that would be otherwise lost.Comment: 9 pages, 3 figure
Biomarkers: a strategic tool in the assessment of environmental quality of coastal waters
Ecosystems are under the pressure of complex mixtures of contaminants whose effects are not always simple to assess. Biomarkers, acting as early warning signals of the presence of potentially toxic xenobiotics, are useful tools for assessing either exposure to, or the effects of these compounds providing information about the toxicant bioavailability. In fact, it has been argued that a full understanding of ecotoxicological processes must consider an integrated multi-level approach, in which molecular impact is related with higher-order biological consequences at the individual, population and community levels. Monitoring programs should make use of this tool to link contaminants and ecological responses fulfilling strategies like those launched by OSPAR (Commissions of Oslo and Paris) Convention on the protection of the marine environment of the North-East Atlantic and the International Council for the Exploration of the Sea (ICES). An overview of the work done in the past few years using biomarkers as in situ tools for pollution assessment in Portuguese coastal waters is presented as a contribution to the set up of a biomonitoring program for the Portuguese coastal zone. Considering the data set available the biomonitoring proposal should include the analysis of biomarkers and effects at individual levels. The aim of the program will include a spatial and temporal characterization of the biomarkers acetyl-cholinesterase, metallothioneins, DNA damage, adenylate energy charge and scope-for-growth levels. The investigation of the spatial variation of biomarkers is crucial to define sites for long term monitoring, which will be integrated with a chemical monitoring program. This framework will be a major contribution to the implementation of a national database for the use of biomarkers along the Portuguese coast.info:eu-repo/semantics/publishedVersio
Dynamic RKKY interaction between magnetic moments in graphene nanoribbons
Graphene has been identified as a promising material with numerous
applications, particularly in spintronics. In this paper we investigate the
peculiar features of spin excitations of magnetic units deposited on graphene
nanoribbons and how they can couple through a dynamical interaction mediated by
spin currents. We examine in detail the spin lifetimes and identify a pattern
caused by vanishing density of states sites in pristine ribbons with armchair
borders. Impurities located on these sites become practically invisible to the
interaction, but can be made accessible by a gate voltage or doping. We also
demonstrate that the coupling between impurities can be turned on or off using
this characteristic, which may be used to control the transfer of information
in transistor-like devices.Comment: 10 pages, 10 figure
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