961 research outputs found
Genetic Characterization of the Tick-Borne Orbiviruses
The International Committee for Taxonomy of Viruses (ICTV) recognizes four species of tick-borne orbiviruses (TBOs): Chenuda virus, Chobar Gorge virus, Wad Medani virus and Great Island virus (genus Orbivirus, family Reoviridae). Nucleotide (nt) and amino acid (aa) sequence comparisons provide a basis for orbivirus detection and classification, however full genome sequence data were only available for the Great Island virus species. We report representative genome-sequences for the three other TBO species (virus isolates: Chenuda virus (CNUV); Chobar Gorge virus (CGV) and Wad Medani virus (WMV)). Phylogenetic comparisons show that TBOs cluster separately from insect-borne orbiviruses (IBOs). CNUV, CGV, WMV and GIV share low level aa/nt identities with other orbiviruses, in 'conserved' Pol, T2 and T13 proteins/genes, identifying them as four distinct virus-species. The TBO genome segment encoding cell attachment, outer capsid protein 1 (OC1), is approximately half the size of the equivalent segment from insect-borne orbiviruses, helping to explain why tick-borne orbiviruses have a ~1 kb smaller genome
Avert the Dirt:On the Design of Scalable Antifouling Polymer Coatings
Whether it be your house, clothes, phone, or precious record collection; everything gets dirty eventually. While we can simply hop in the shower or clean most of our belongings using basic cleaning supplies, the same does not apply to medical, marine, and industrial devices. Here, the uncontrollable and unwanted adhesion of all kinds of material, generally known as fouling, leads to serious complications related to health risks, pollution, and financial losses, which cannot be easily solved by the mere power of detergent. As a response, we strived to develop a novel antifouling coating, specifically designed for large-scale underwater applications. This protective layer consists of polymers: very long and flexible molecules. By attaching these individual polymers or polymer clusters to a surface one by one, a brush is formed, also known as a polymer brush. By repeating this adsorption step, but with a different type of polymer (cluster), the density of the brush is increased. Because of the high brush density and the used polymers’ antifouling character, fouling particles are unable to adhere to the coated surface and the surface remains clean. This simple two-step adsorption strategy has enabled the formation of an effective and reversible antifouling layer, which should allow the straightforward coating and protection of large-scale (underwater) applications. This way, we hope to contribute to a cleaner and more sustainable future
Dynamics of liquid crystalline domains in magnetic field
We study microscopic single domains nucleating and growing within the
coexistence region of the Isotropic (I) and Nematic (N) phases in magnetic
field. By rapidly switching on the magnetic field the time needed to align the
nuclei of sufficiently large size is measured, and is found to decrease with
the square of the magnetic field. When the field is removed the disordering
time is observed to last on a longer time scale. The growth rate of the nematic
domains at constant temperature within the coexistence region is found to
increase when a magnetic field is applied.Comment: 10 pages, 5 figures, unpublishe
Linear magnetoresistance in a quasi-free two dimensional electron gas in an ultra-high mobility GaAs quantum well
We report a magnetotransport study of an ultra-high mobility
(\,cm\,V\,s) -type GaAs
quantum well up to 33 T. A strong linear magnetoresistance (LMR) of the order
of 10 % is observed in a wide temperature range between 0.3 K and 60 K. The
simplicity of our material system with a single sub-band occupation and free
electron dispersion rules out most complicated mechanisms that could give rise
to the observed LMR. At low temperature, quantum oscillations are superimposed
onto the LMR. Both, the featureless LMR at high and the quantum
oscillations at low follow the empirical resistance rule which states that
the longitudinal conductance is directly related to the derivative of the
transversal (Hall) conductance multiplied by the magnetic field and a constant
factor that remains unchanged over the entire temperature range. Only
at low temperatures, small deviations from this resistance rule are observed
beyond that likely originate from a different transport mechanism for
the composite fermions
Manipulating quantum Hall edge channels in graphene through Scanning Gate Microscopy
We show evidence of the backscattering of quantum Hall edge channels in a
narrow graphene Hall bar, induced by the gating effect of the conducting tip of
a Scanning Gate Microscope, which we can position with nanometer precision. We
show full control over the edge channels and are able, due to the spatial
variation of the tip potential, to separate co-propagating edge channels in the
Hall bar, creating junctions between regions of different charge carrier
density, that have not been observed in devices based on top- or split-gates.
The solution of the corresponding quantum scattering problem is presented to
substantiate these results, and possible follow-up experiments are discussed.Comment: 10 pages, 12 figure
Electron-phonon coupling in the two phonon mode ternary alloy quantum well
We have investigated the infrared transmission of a two-dimensional (2DEG)
electron gas confined in a single
quantum well in order to study the electron optical phonon interaction in a two
phonon mode system. Infrared transmission experiments have been performed in
both the perpendicular Faraday (PF) and tilted Faraday (TF) configurations for
which the growth axis of the sample is tilted with respect to the incident
light propagation direction and to the magnetic field direction. The
experimental results lead to question the validity of the concept of polaron
mass in a real material.Comment: 7 pages, 3 figure
An Unusual Anterior Neck Injury [Cut Throat]: A Case Report
Introduction –The Neck is prone to injuries that are life threatening due to the presence of vital structures that lie within the neck. Cut throat injuries are located on the anterior neck classically, with dangers to the aero digestive tract and the vascular structures. Case Presentation-A 40 year old farmer presented with injuries on the lateral sides of the neck with an island of normal tissue anteriorly two days after the incidence from a rural hospital, fig 1. Examination revealed an anaemic, dehydrated young man that was not in any respiratory distress. There was complete avulsion of the epiglottis at the base; and the eyes were also plucked. Patient had blood transfusion, tracheostomy, fig 2 and subsequent repair with favourable outcome. Conclusion-Cut throat injuries are relatively uncommon in our environment, but on the increase due to violence in the society (insurgency, ritual killings, armed robbery etc).Prompt identification and referral to the specialist for proper management will reduce morbidity and mortality. Keywords: unusual, anterior neck, injury DOI: 10.7176/JHMN/63-06 Publication date:June 30th 2019
Lifting of the Landau level degeneracy in graphene devices in a tilted magnetic field
We report on transport and capacitance measurements of graphene devices in
magnetic fields up to 30 T. In both techniques, we observe the full splitting
of Landau levels and we employ tilted field experiments to address the origin
of the observed broken symmetry states. In the lowest energy level, the spin
degeneracy is removed at filling factors and we observe an enhanced
energy gap. In the higher levels, the valley degeneracy is removed at odd
filling factors while spin polarized states are formed at even . Although
the observation of odd filling factors in the higher levels points towards the
spontaneous origin of the splitting, we find that the main contribution to the
gap at , and is due to the Zeeman energy.Comment: 5 pages, 4 figure
Transport Gap in Suspended Bilayer Graphene at Zero Magnetic Field
We report a change of three orders of magnitudes in the resistance of a
suspended bilayer graphene flake which varies from a few ks in the high
carrier density regime to several Ms around the charge neutrality point
(CNP). The corresponding transport gap is 8 meV at 0.3 K. The sequence of
appearing quantum Hall plateaus at filling factor followed by
suggests that the observed gap is caused by the symmetry breaking of the lowest
Landau level. Investigation of the gap in a tilted magnetic field indicates
that the resistance at the CNP shows a weak linear decrease for increasing
total magnetic field. Those observations are in agreement with a spontaneous
valley splitting at zero magnetic field followed by splitting of the spins
originating from different valleys with increasing magnetic field. Both, the
transport gap and field response point toward spin polarized layer
antiferromagnetic state as a ground state in the bilayer graphene sample. The
observed non-trivial dependence of the gap value on the normal component of
suggests possible exchange mechanisms in the system.Comment: 8 pages, 5 figure
Transport and thermoelectric properties of the LaAlO/SrTiO interface
The transport and thermoelectric properties of the interface between
SrTiO and a 26-monolayer thick LaAlO-layer grown at high
oxygen-pressure have been investigated at temperatures from 4.2 K to 100 K and
in magnetic fields up to 18 T. For 4.2 K, two different electron-like
charge carriers originating from two electron channels which contribute to
transport are observed. We probe the contributions of a degenerate and a
non-degenerate band to the thermoelectric power and develop a consistent model
to describe the temperature dependence of the thermoelectric tensor. Anomalies
in the data point to an additional magnetic field dependent scattering.Comment: 7 pages, 4 figure
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