341 research outputs found
Simulations of Time-Resolved X-Ray Diffraction in Laue Geometry
A method of computer simulation of Time-Resolved X-ray Diffraction (TRXD) in
asymmetric Laue (transmission) geometry with an arbitrary propagating strain
perpendicular to the crystal surface is presented. We present two case studies
for possible strain generation by short-pulse laser irradiation: (i) a
thermoelastic-like analytic model; (ii) a numerical model including effects of
electron-hole diffusion, Auger recombination, deformation potential and thermal
diffusion. A comparison with recent experimental results is also presented.Comment: 9 pages, 11 figure
Coronal lines and the importance of deep core-valence correlation in Ag-like ions
We report on large-scale and critically evaluated {\em ab initio} MCDHF
calculations of the wavelength of the "coronal", M1 transition $4f\
^2\mathrm{F}_{5/2}^o-^2\mathrm{F}_{7/2}^oZ
\ge 62^{23+}^{27+}Z = 5094n=3$ shell in the theoretical model is emphasized. The
results show close to spectroscopic accuracy for these forbidden lines.Comment: 10 pages, 5 figures, 3 table
Phase retrieval from single biomolecule diffraction pattern
In this paper, we propose the SPR (sparse phase retrieval) method, which is a
new phase retrieval method for coherent x-ray diffraction imaging (CXDI).
Conventional phase retrieval methods effectively solve the problem for high
signal-to-noise ratio measurements, but would not be sufficient for single
biomolecular imaging which is expected to be realized with femto-second x-ray
free electron laser pulses. The SPR method is based on the Bayesian statistics.
It does not need to set the object boundary constraint that is required by the
commonly used hybrid input-output (HIO) method, instead a prior distribution is
defined with an exponential distribution and used for the estimation.
Simulation results demonstrate that the proposed method reconstructs the
electron density under a noisy condition even some central pixels are masked.Comment: 13 pages, 13 figures, submitted for a journa
Investigation of M1 transitions of the ground-state configuration of In-like Tungsten
Three visible lines of M1 transitions from In-like W were recorded using the
Shanghai permanent magnet electron beam ion trap. The experimental wavelengths
were measured as 493.84 0.15, 226.97 0.13 and 587.63 0.23 nm
(vacuum wavelengths). These results are in good agreement with theoretical
predictions obtained using large-scale Relativistic Many-Body Perturbation
Theory, in the form of the Flexible Atomic Code.Comment: 7 pages, 3 figure
Multiscale Modeling of a Nanoelectromechanical Shuttle
In this article, we report a theoretical analysis of a nanoelectromechanical
shuttle based on a multiscale model that combines microscopic electronic
structure data with macroscopic dynamics. The microscopic part utilizes a
(static) density functional description to obtain the energy levels and
orbitals of the shuttling particle together with the forces acting on the
particle. The macroscopic part combines stochastic charge dynamics that
incorporates the microscopically evaluated tunneling rates with a Newtonian
dynamics.
We have applied the multiscale model to describe the shuttling of a single
copper atom between two gold-like jellium electrodes. We find that energy
spectrum and particle surface interaction greatly influence shuttling dynamics;
in the specific example that we studied the shuttling is found to involve only
charge states Q=0 and Q=+e. The system is found to exhibit two quasi-stable
shuttling modes, a fundamental one and an excited one with a larger amplitude
of mechanical motion, with random transitions between them.Comment: 9 pages, 9 figure
Behandling av akne
Akne bør ikke oppfattes som en selvbegrensende ungdomsplage. På grunn av økende problemer med antibiotikaresistente bakterier anbefales restriktiv bruk av peroral og topikal antibiotika. Det finnes flere effektive midler for topikal behandling av lite til moderat uttalt akne. Ved uttalt, terapiresistent akne anbefales behandling med peroral isotretinoin
Modeling human pancreatic beta cell dedifferentiation
Objective: Dedifferentiation could explain reduced functional pancreatic β-cell mass in type 2 diabetes (T2D). Methods: Here we model human β-cell dedifferentiation using growth factor stimulation in the human β-cell line, EndoC-βH1, and human pancreatic islets. Results: Fibroblast growth factor 2 (FGF2) treatment reduced expression of β-cell markers, (INS, MAFB, SLC2A2, SLC30A8, and GCK) and activated ectopic expression of MYC, HES1, SOX9, and NEUROG3. FGF2-induced dedifferentiation was time- and dose-dependent and reversible upon wash-out. Furthermore, FGF2 treatment induced expression of TNFRSF11B, a decoy receptor for RANKL and protected β-cells against RANKL signaling. Finally, analyses of transcriptomic data revealed increased FGF2 expression in ductal, endothelial, and stellate cells in pancreas from T2D patients, whereas FGFR1, SOX,9 and HES1 expression increased in islets from T2D patients. Conclusions: We thus developed an FGF2-induced model of human β-cell dedifferentiation, identified new markers of dedifferentiation, and found evidence for increased pancreatic FGF2, FGFR1, and β-cell dedifferentiation in T2D
Atomic Processes in Planetary Nebulae and H II Regions
Spectroscopic studies of Planetary Nebulae (PNe) and H {\sc ii} regions have
driven much development in atomic physics. In the last few years the
combination of a generation of powerful observatories, the development of ever
more sophisticated spectral modeling codes, and large efforts on mass
production of high quality atomic data have led to important progress in our
understanding of the atomic spectra of such astronomical objects. In this paper
I review such progress, including evaluations of atomic data by comparisons
with nebular spectra, detection of spectral lines from most iron-peak elements
and n-capture elements, observations of hyperfine emission lines and analysis
of isotopic abundances, fluorescent processes, and new techniques for
diagnosing physical conditions based on recombination spectra. The review is
directed toward atomic physicists and spectroscopists trying to establish the
current status of the atomic data and models and to know the main standing
issues.Comment: 9 pages, 1 figur
Management of Ocular Manifestations of Atopic Dermatitis : A Consensus Meeting Using a Modified Delphi Process
There is a need for unified guidance on the management of ocular manifestations of atopic dermatitis and ocular manifestations associated with dupilumab in the Nordic region (Denmark, Finland, Norway and Sweden). This initiative gathered Nordic dermatologists and ophthalmologists to identify consensus in this area using a modified Delphi process. The initiative was led by a Nordic expert panel who developed a questionnaire that was circulated to a wider group. The results informed an agenda consisting of 24 statements to be voted on using a 5-point Likert scale at a meeting in Copenhagen on 24 April 2019. A facilitator moderated discussion and revised statements according to expert feedback for a second vote when required to reach consensus. Consensus was reached for 23 statements regarding the diagnosis, treatment and referral of these patients, which we hope will improve patient management in the Nordic region.Peer reviewe
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