7,323 research outputs found
Scanning tunneling microscopy and spectroscopy of the electronic local density of states of graphite surfaces near monoatomic step edges
We measured the electronic local density of states (LDOS) of graphite
surfaces near monoatomic step edges, which consist of either the zigzag or
armchair edge, with the scanning tunneling microscopy (STM) and spectroscopy
(STS) techniques. The STM data reveal that the and honeycomb superstructures coexist over a length scale of 3-4 nm
from both the edges. By comparing with density-functional derived nonorthogonal
tight-binding calculations, we show that the coexistence is due to a slight
admixing of the two types of edges at the graphite surfaces. In the STS
measurements, a clear peak in the LDOS at negative bias voltages from -100 to
-20 mV was observed near the zigzag edges, while such a peak was not observed
near the armchair edges. We concluded that this peak corresponds to the
graphite "edge state" theoretically predicted by Fujita \textit{et al.} [J.
Phys. Soc. Jpn. {\bf 65}, 1920 (1996)] with a tight-binding model for graphene
ribbons. The existence of the edge state only at the zigzag type edge was also
confirmed by our first-principles calculations with different edge
terminations.Comment: 20 pages, 11 figure
Entanglement, Haag-duality and type properties of infinite quantum spin chains
We consider an infinite spin chain as a bipartite system consisting of the
left and right half-chain and analyze entanglement properties of pure states
with respect to this splitting. In this context we show that the amount of
entanglement contained in a given state is deeply related to the von Neumann
type of the observable algebras associated to the half-chains. Only the type I
case belongs to the usual entanglement theory which deals with density
operators on tensor product Hilbert spaces, and only in this situation
separable normal states exist. In all other cases the corresponding state is
infinitely entangled in the sense that one copy of the system in such a state
is sufficient to distill an infinite amount of maximally entangled qubit pairs.
We apply this results to the critical XY model and show that its unique ground
state provides a particular example for this type of entanglement.Comment: LaTeX2e, 34 pages, 1 figure (pstricks
Novel results in STM, ARPES, HREELS, Nernst, neutron, Raman, and isotope substitution experiments and their relation to bosonic modes and charge inhomogeneity, from perspective of negative-Ueff boson-fermion modelling of HTSC
This paper seeks to synthesize much recent work on the HTSC materials around
the latest STM results from Davis and coworkers. The conductance diffuse
scattering results in particular are used as point of entry to discuss bosonic
modes, both of condensed and uncondensed form. The bosonic mode picture is
essential to understanding an ever growing range of observations within the
HTSC field. The work is expounded within the context of the negative-U,
boson-fermion modelling long advocated by the author. This general approach is
presently seeing much theoretical development, into which I have looked to
couple many of the experimental advances. While the formal theory is not yet
sufficiently detailed to cover adequately all the experimental complexities
presented by the real cuprate systems, it is clear that it affords very
appreciable support to the line taken. An attempt is made throughout to say why
and how it is that these events are tied so very closely to this particular set
of materials.Comment: 36 pages pdf with 3 figures and 1 table included, Submitted to J.
Phys. Cond. Mat
Galactic-Center Hyper-Shell Model for the North Polar Spurs
The bipolar-hyper shell (BHS) model for the North Polar Spurs (NPS-E, -W, and
Loop I) and counter southern spurs (SPS-E and -W) is revisited based on
numerical hydrodynamical simulations. Propagations of shock waves produced by
energetic explosive events in the Galactic Center are examined. Distributions
of soft X-ray brightness on the sky at 0.25, 0.7, and 1.5 keV in a +/-50 deg x
+/-50 deg region around the Galactic Center are modeled by thermal emission
from high-temperature plasma in the shock-compressed shell considering
shadowing by the interstellar HI and H2 gases. The result is compared with the
ROSAT wide field X-ray images in R2, 4 and 6 bands. The NPS and southern spurs
are well reproduced by the simulation as shadowed dumbbell-shaped shock waves.
We discuss the origin and energetics of the event in relation to the starburst
and/or AGN activities in the Galactic Center. [ High resolution pdf is
available at http://www.ioa.s.u-tokyo.ac.jp/~sofue/htdocs/2016bhs/ ]Comment: 13 pages, 20 figures; To appear in MNRA
Effective radii of deuteron induced reactions
The continuum-discretized coupled-channels method (CDCC) for exclusive
reactions and the eikonal reaction theory (ERT) as an extension of CDCC to
inclusive reactions are applied to deuteron induced reactions. The CDCC result
reproduces experimental data on the reaction cross section for Ni
scattering at 200 MeV/nucleon and ERT does data on the neutron-stripping cross
section for inclusive Li reaction at 40 MeV. For deuteron induced
reactions at 200 MeV/nucleon, target-dependence of the reaction,
elastic-breakup, nucleon-stripping, nucleon-removal, complete- and
incomplete-fusion cross sections is clearly explained by simple formulae.
Accuracy of the Glauber model is also investigated.Comment: 11 pages, 11 figures, 2 table
Void-induced cross slip of screw dislocations in fcc copper
Pinning interaction between a screw dislocation and a void in fcc copper is
investigated by means of molecular dynamics simulation. A screw dislocation
bows out to undergo depinning on the original glide plane at low temperatures,
where the behavior of the depinning stress is consistent with that obtained by
a continuum model. If the temperature is higher than 300 K, the motion of a
screw dislocation is no longer restricted to a single glide plane due to cross
slip on the void surface. Several depinning mechanisms that involve multiple
glide planes are found. In particular, a depinning mechanism that produces an
intrinsic prismatic loop is found. We show that these complex depinning
mechanisms significantly increase the depinning stress
Fundamental and clinical evaluation of "SCC RIABEAD" kit for immuno radiometric assay of squamous cell carcinoma related antigen.
Classic vector control strategies target mosquitoes indoors as the main transmitters of malaria are indoor-biting and –resting mosquitoes. However, the intensive use of insecticide-treated bed-nets (ITNs) and indoor residual spraying have put selective pressure on mosquitoes to adapt in order to obtain human blood meals. Thus, early-evening and outdoor vector activity is becoming an increasing concern. This study assessed the effect of a deltamethrin-treated net (100 mg/m2) attached to a one-meter high fence around outdoor cattle enclosures on the number of mosquitoes landing on humans. Mosquitoes were collected from four cattle enclosures: Pen A – with cattle and no net; B – with cattle and protected by an untreated net; C – with cattle and protected by a deltamethrin-treated net; D – no cattle and no net. A total of 3217 culicines and 1017 anophelines were collected, of which 388 were Anopheles gambiae and 629 An. ziemanni. In the absence of cattle nearly 3 times more An. gambiae (p<0.0001) landed on humans. The deltamethrin-treated net significantly reduced (nearly three-fold, p<0.0001) culicine landings inside enclosures. The sporozoite rate of the zoophilic An. ziemanni, known to be a secondary malaria vector, was as high as that of the most competent vector An. gambiae; raising the potential of zoophilic species as secondary malaria vectors. After deployment of the ITNs a deltamethrin persistence of 9 months was observed despite exposure to African weather conditions. The outdoor use of ITNs resulted in a significant reduction of host-seeking culicines inside enclosures. Further studies investigating the effectiveness and spatial repellence of ITNs around other outdoor sites, such as bars and cooking areas, as well as their direct effect on vector-borne disease transmission are needed to evaluate its potential as an appropriate outdoor vector control tool for rural Africa
Steady state fluctuations of the dissipated heat for a quantum stochastic model
We introduce a quantum stochastic dynamics for heat conduction. A multi-level
subsystem is coupled to reservoirs at different temperatures. Energy quanta are
detected in the reservoirs allowing the study of steady state fluctuations of
the entropy dissipation. Our main result states a symmetry in its large
deviation rate function.Comment: 41 pages, minor changes, published versio
BCS-like Bogoliubov Quasiparticles in High-Tc Superconductors Observed by Angle-Resolved Photoemission Spectroscopy
We performed high-resolution angle-resolved photoemission spectroscopy on
triple-layered high-Tc cuprate Bi2Sr2Ca2Cu3O10+delta. We have observed the full
energy dispersion (electron and hole branches) of Bogoliubov quasiparticles and
determined the coherence factors above and below EF as a function of momentum
from the spectral intensity as well as from the energy dispersion based on BCS
theory. The good quantitative agreement between the experiment and the
theoretical prediction suggests the basic validity of BCS formalism in
describing the superconducting state of cuprates.Comment: 4 pages, 3 figure
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