2,184 research outputs found
Magneto-Transport in MoS2: Phase Coherence, Spin Orbit Scattering and the Hall Factor
We have characterized phase coherence length, spin orbit scattering length,
and the Hall factor in n-type MoS2 2D crystals via weak localization
measurements and Hall-effect measurements. Weak localization measurements
reveal a phase coherence length of ~50 nm at T = 400 mK for a few-layer MoS2
film, decreasing as T^-1/2 with increased temperatures. Weak localization
measurements also allow us, for the first time without optical techniques, to
estimate the spin orbit scattering length to be 430 nm, pointing to the
potential of MoS2 for spintronics applications. Via Hall-effect measurements,
we observe a low temperature Hall mobility of 311 cm2/Vs at T = 1 K which
decreases as a power law with a characteristic exponent {\gamma}=1.5 from 10 K
to 60 K. At room temperature, we observe Hall mobility of 24 cm2/Vs. By
determining the Hall factor for MoS2 to be 1.35 at T = 1 K and 2.4 at room
temperature, we observe drift mobility of 420 cm2/Vs and 56 cm2/Vs at T = 1 K
and room temperature, respectively.Comment: ACS Nano nn402377
The genome of Anopheles darlingi, the main neotropical malaria vector
Anopheles darlingi is the principal neotropical malaria vector, responsible for more than a million cases of malaria per year on the American continent. Anopheles darlingi diverged from the African and Asian malaria vectors approximately 100 million years ago (mya) and successfully adapted to the New World environment. Here we present an annotated reference A. darlingi genome, sequenced from a wild population of males and females collected in the Brazilian Amazon. A total of 10 481 predicted protein-coding genes were annotated, 72% of which have their closest counterpart in Anopheles gambiae and 21% have highest similarity with other mosquito species. In spite of a long period of divergent evolution, conserved gene synteny was observed between A. darlingi and A. gambiae. More than 10 million single nucleotide polymorphisms and short indels with potential use as genetic markers were identified. Transposable elements correspond to 2.3% of the A. darlingi genome. Genes associated with hematophagy, immunity and insecticide resistance, directly involved in vector-human and vector-parasite interactions, were identified and discussed. This study represents the first effort to sequence the genome of a neotropical malaria vector, and opens a new window through which we can contemplate the evolutionary history of anopheline mosquitoes. It also provides valuable information that may lead to novel strategies to reduce malaria transmission on the South American continent. The A. darlingi genome is accessible at www.labinfo.lncc.br/index.php/anopheles-darlingi
Identifying Needs and Implementing Organizational Change to Improve Retention of Early-Career Agents
Retention of agents is important for the growth and stability of Cooperative Extension. A study of early-career agents in Virginia Cooperative Extension identified specific areas in which organizational change could be made to improve agent fit in the organization and long-term retention. As a result, numerous changes have been made, particularly associated with existing agents but also in work with prospective agents. Although this article relates specifically to Virginia, the challenges and solutions identified may be relevant to other programs and to national professional development organizations
Quantum-Hall plateau-plateau transition in top-gated epitaxial graphene grown on SiC (0001)
We investigate the low-temperature magneto-transport properties of monolayer
epitaxial graphene films formed on the Si-face of semi-insulating 4H-SiC
substrates by a high temperature sublimation process. A high-k top-gate on the
epitaxial graphene is realized by inserting a fully oxidized nanometer thin
aluminum film as a seeding layer, followed by an atomic layer deposition
process. At low temperatures, the devices demonstrate a strong field effect by
the top gate with an on/off ratio of ~7 and an electron mobility up to ~3250
cm^2/Vs. After the observation of the half-integer quantum Hall effect for
monolayer epitaxial graphene films, detailed magneto-transport measurements
have been carried out including varying densities, temperatures, magnetic
fields and currents. We study the width of the distinguishable quantum-Hall
plateau to plateau transition (Landau level index n=0 to n=1) as temperature
(T) and current are varied. For both gate voltage and magnetic field sweeps and
T>10 K the transition width goes as T^{-\kappa} with exponent \kappa ~0.42.
This universal scaling exponent agrees well with those found in III-V
heterojunctions with short range alloy disorders and in exfoliated graphene.Comment: accepted by Journal of Applied Physic
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