668 research outputs found
Bulk and surface-sensitive high-resolution photoemission study of Mott-Hubbard systems SrVO and CaVO
We study the electronic structure of Mott-Hubbard systems SrVO and
CaVO with bulk and surface-sensitive high-resolution photoemission
spectroscopy (PES), using a VUV laser, synchrotron radiation and a discharge
lamp ( = 7 - 21 eV). A systematic suppression of the density of states
(DOS) within 0.2 eV of the Fermi level () is found on decreasing
photon energy i.e. on increasing bulk sensitivity. The coherent band in
SrVO and CaVO is shown to consist of surface and bulk derived
features, separated in energy. The stronger distortion on surface of CaVO
compared to SrVO leads to higher surface metallicity in the coherent DOS
at , consistent with recent theory.Comment: 4 pages 5 figures (including 2 auxiliary figures); A complete
analysis of the spectra based on the surface and bulk analysis shows in
auxiliary figures Fig. A1 and A
Recursiveness, Switching, and Fluctuations in a Replicating Catalytic Network
A protocell model consisting of mutually catalyzing molecules is studied in
order to investigate how chemical compositions are transferred recursively
through cell divisions under replication errors. Depending on the path rate,
the numbers of molecules and species, three phases are found: fast switching
state without recursive production, recursive production, and itinerancy
between the above two states. The number distributions of the molecules in the
recursive states are shown to be log-normal except for those species that form
a core hypercycle, and are explained with the help of a heuristic argument.Comment: 4 pages (with 7 figures (6 color)), submitted to PR
Orbital-dependent modifications of electronic structure across magneto-structural transition in BaFe2As2
Laser angle-resolved photoemission spectroscopy (ARPES) is employed to
investigate the temperature (T) dependence of the electronic structure in
BaFe2As2 across the magneto-structural transition at TN ~ 140 K. A drastic
transformation in Fermi surface (FS) shape across TN is observed, as expected
by first-principles band calculations. Polarization-dependent ARPES and band
calculations consistently indicate that the observed FSs at kz ~ pi in the
low-T antiferromagnetic (AF) state are dominated by the Fe3dzx orbital, leading
to the two-fold electronic structure. These results indicate that
magneto-structural transition in BaFe2As2 accompanies orbital-dependent
modifications in the electronic structure.Comment: 13 pages, 4 figures. accepted by Physical Review Letter
Transitions Induced by the Discreteness of Molecules in a Small Autocatalytic System
Autocatalytic reaction system with a small number of molecules is studied
numerically by stochastic particle simulations. A novel state due to
fluctuation and discreteness in molecular numbers is found, characterized as
extinction of molecule species alternately in the autocatalytic reaction loop.
Phase transition to this state with the change of the system size and flow is
studied, while a single-molecule switch of the molecule distributions is
reported. Relevance of the results to intracellular processes are briefly
discussed.Comment: 5 pages, 4 figure
Doping-dependence of nodal quasiparticle properties in high- cuprates studied by laser-excited angle-resolved photoemission spectroscopy
We investigate the doping dependent low energy, low temperature ( = 5 K)
properties of nodal quasiparticles in the d-wave superconductor
BiSrCaCuO (Bi2212). By utilizing ultrahigh
resolution laser-excited angle-resolved photoemission spectroscopy, we obtain
precise band dispersions near , mean free paths and scattering rates
() of quasiparticles. For optimally and overdoped, we obtain very sharp
quasiparticle peaks of 8 meV and 6 meV full-width at half-maximum,
respectively, in accord with terahertz conductivity. For all doping levels, we
find the energy-dependence of , while () shows a monotonic increase from overdoping to underdoping. The doping
dependence suggests the role of electronic inhomogeneity on the nodal
quasiparticle scattering at low temperature (5 K \lsim 0.07T_{\rm c}),
pronounced in the underdoped region
Creation and Reproduction of Model Cells with Semipermeable Membrane
A high activity of reactions can be confined in a model cell with a
semipermeable membrane in the Schl\"ogl model. It is interpreted as a model of
primitive metabolism in a cell. We study two generalized models to understand
the creation of primitive cell systems conceptually from the view point of the
nonlinear-nonequilibrium physics. In the first model, a single-cell system with
a highly active state confined by a semipermeable membrane is spontaneously
created from an inactive homogeneous state by a stochastic jump process. In the
second model, many cell structures are reproduced from a single cell, and a
multicellular system is created.Comment: 11 pages, 7 figure
Nonlinearity of Mechanochemical Motions in Motor Proteins
The assumption of linear response of protein molecules to thermal noise or
structural perturbations, such as ligand binding or detachment, is broadly used
in the studies of protein dynamics. Conformational motions in proteins are
traditionally analyzed in terms of normal modes and experimental data on
thermal fluctuations in such macromolecules is also usually interpreted in
terms of the excitation of normal modes. We have chosen two important protein
motors - myosin V and kinesin KIF1A - and performed numerical investigations of
their conformational relaxation properties within the coarse-grained elastic
network approximation. We have found that the linearity assumption is deficient
for ligand-induced conformational motions and can even be violated for
characteristic thermal fluctuations. The deficiency is particularly pronounced
in KIF1A where the normal mode description fails completely in describing
functional mechanochemical motions. These results indicate that important
assumptions of the theory of protein dynamics may need to be reconsidered.
Neither a single normal mode, nor a superposition of such modes yield an
approximation of strongly nonlinear dynamics.Comment: 10 pages, 6 figure
European society of urogenital radiology (ESUR) guidelines: MR imaging of pelvic endometriosis
Endometriosis is a common gynaecological condition of unknown
aetiology that primarily affects women of reproductive
age. The accepted first-line imaging modality is pelvic ultrasound.
However, magnetic resonance imaging (MRI) is increasingly
performed as an additional investigation in complex cases and for surgical planning. There is currently
no international consensus regarding patient preparation, MRI
protocols or reporting criteria. Our aim was to develop clinical
guidelines for MRI evaluation of pelvic endometriosis based
on literature evidence and consensus expert opinion. This
work was performed by a group of radiologists from the European Society of Urogenital Radiology (ESUR), experts in
gynaecological imaging and a gynaecologist expert in methodology.
The group discussed indications for MRI, technical
requirements, patient preparation, MRI protocols and criteria
for the diagnosis of pelvic endometriosis on MRI. The expert
panel proposed a final recommendation for each criterion
using Oxford Centre for Evidence Based Medicine
(OCEBM) 2011 levels of evidence.info:eu-repo/semantics/publishedVersio
Staging of uterine cervical cancer with MRI: guidelines of the european society of urogenital radiology
Objective: To design clear guidelines for the
staging and follow-up of patients with uterine cervical
cancer, and to provide the radiologist with a framework for
use in multidisciplinary conferences. Methods: Guidelines
for uterine cervical cancer staging and follow-up were
defined by the female imaging subcommittee of the ESUR
(European Society of Urogenital Radiology) based on the
expert consensus of imaging protocols of 11 leading
institutions and a critical review of the literature. Results:
The results indicated that high field Magnetic Resonance
Imaging (MRI) should include at least two T2-weighted
sequences in sagittal, axial oblique or coronal obliqu
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Functional trait variation related to gap dynamics in tropical moist forests: a vegetation modelling perspective
The conventional representation of Plant Functional Types (PFTs) in Dynamic Global Vegetation Models (DGVMs) is increasingly recognized as simplistic and lacking in predictive power. Key ecophysiological traits, including photosynthetic parameters, are typically assigned single values for each PFT while the substantial trait variation within PFTs is neglected. This includes continuous variation in response to environmental factors, and differences linked to spatial and temporal niche differentiation within communities. A much stronger empirical basis is required for the treatment of continuous plant functional trait variation in DGVMs. We analyse 431 sets of measurements of leaf and plant traits, including photosynthetic measurements, on evergreen angiosperm trees in tropical moist forests of Australia and China. Confining attention to tropical moist forests, our analysis identifies trait differences that are linked to vegetation dynamic roles. Coordination theory predicts that Rubisco- and electron-transport limited rates of photosynthesis are co-limiting under field conditions. The least-cost hypothesis predicts that air-to-leaf CO2 drawdown minimizes the combined costs per unit carbon assimilation of maintaining carboxylation and transpiration capacities. Aspects of these predictions are supported for within-community trait variation linked to canopy position, just as they are for variation along spatial environmental gradients. Trait differences among plant species occupying different structural and temporal niches may provide a basis for the ecophysiological representation of vegetation dynamics in next-generation DGVMs
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