86 research outputs found
XUV spectroscopy of highly excited states in H2, HD en D2
Ubachs, W.M.G. [Promotor]Lange, C.A. de [Promotor
HD as a probe for detecting mass variation on a cosmological time scale
The strong electronic absorption systems of the B-1 Sigma(+)(u)-X-1 Sigma(+)(g) Lyman and the C-1 Pi(u)-X-1 Sigma(+)(g) Werner bands can be used to probe possible mass-variation effects on a cosmological time scale from spectra observed at high redshift, not only in H-2 but also in the second most abundant hydrogen isotopomer HD. High resolution laboratory determination of the most prominent HD lines at extreme ultraviolet wavelengths is performed at an accuracy of Delta lambda/lambda similar to 5x10(-8), forming a database for comparison with astrophysical data. Sensitivity coefficients K-i=dln lambda(i)/dln mu are determined for HD from quantum ab initio calculations as a function of the proton-electron mass ratio mu. Strategies to deduce possible effects beyond first-order baryon/lepton mass ratio deviations are discussed
Stability of homogeneous magnetic phases in a generalized t-J model
We study the stability of homogeneous magnetic phases in a generalized t-J
model including a same-sublattice hopping t' and nearest-neighbor repulsion V
by means of the slave fermion-Schwinger boson representation of spin operators.
At mean-field order we find, in agreement with other authors, that the
inclusion of further-neighbor hopping and Coulomb repulsion makes the
compressibility positive, thereby stabilizing at this level the spiral and Neel
orders against phase separation. However, the consideration of Gaussian
fluctuation of order parameters around these mean-field solutions produces
unstable modes in the dynamical matrix for all relevant parameter values,
leaving only reduced stability regions for the Neel phase. We have computed the
one-loop corrections to the energy in these regions, and have also briefly
considered the effects of the correlated hopping term that is obtained in the
reduction from the Hubbard to the t-J model.Comment: 5 pages, 5 figures, Revte
Сравнительная эффективность современных методик анестезиологического пособия при бронхоскопиях у детей
The study, described in this article, was conducted on the basis of 45 bronchoscopies of children ill the age from 6 months till 14 years old. The aim of the studv was a determination of optimum anestesiоlogical procedure. The analysis of hemodynamic data, pustanestetie recovery and conscious mind activityof patients who underwent narcosis was made in different groiip of the patients, the result presented tallies I'licre are also given several charts of the anestesiоlogical procedures.В данной статье приведены результаты исследований на основание 45 бронхоскопий у детей от 6 месяцев и до 14 лет. Цель исследования - оптимизировать процедуру анестезии
Solutions of multi-component NLS models and spinor Bose-Einstein condensates
A three- and five-component nonlinear Schrodinger-type models, which describe
spinor Bose-Einstein condensates (BEC's) with hyperfine structures F=1 and F=2
respectively, are studied. These models for particular values of the coupling
constants are integrable by the inverse scattering method. They are related to
symmetric spaces of BD.I-type SO(2r+1)/(SO(2) x SO(2r-1)) for r=2 and r=3.
Using conveniently modified Zakharov-Shabat dressing procedure we obtain
different types of soliton solutions.Comment: 12 pages, LaTeX, no figures, elsart styl
Extreme ultraviolet laser calibration of D-2 Lyman and Werner transitions
- X-1 Sigma(+)(g)(0,0) Werner band of the D-2 molecule were measured using a narrowband tunable extreme-ultraviolet laser source, at an unprecedented accuracy of Delta lambda/lambda = 6 x 10(-8). The results bear relevance for future use in the calibration of dense classical spectra obtained for the HD and D-2 hydrogen isotopologues
Hamiltonian approach to the ac Josephson effect in superconducting-normal hybrid systems
The ac Josephson effect in hybrid systems of a normal mesoscopic conductor
coupled to two superconducting (S) leads is investigated theoretically. A
general formula of the ac components of time-dependent current is derived which
is valid for arbitrary interactions in the normal region. We apply this formula
to analyze a S-normal-S system where the normal region is a noninteracting
single level quantum dot. We report the physical behavior of time-averaged
nonequilibrium distribution of electrons in the quantum dot, the formation of
Andreev bound states, and ac components of the time-dependent current. The
distribution is found to exhibit a population inversion; and all Andreev bound
states between the superconducting gap carry the same amount of
current and in the same flow direction. The ac components of time-dependent
current show strong oscillatory behavior in marked contrast to the subharmonic
gap structure of the average current.Comment: 23 pages, 10 figures, LaTe
Search for varying constants of nature from astronomical observation of molecules
The status of searches for possible variation in the constants of nature from
astronomical observation of molecules is reviewed, focusing on the
dimensionless constant representing the proton-electron mass ratio
. The optical detection of H and CO molecules with large
ground-based telescopes (as the ESO-VLT and the Keck telescopes), as well as
the detection of H with the Cosmic Origins Spectrograph aboard the Hubble
Space Telescope is discussed in the context of varying constants, and in
connection to different theoretical scenarios. Radio astronomy provides an
alternative search strategy bearing the advantage that molecules as NH
(ammonia) and CHOH (methanol) can be used, which are much more sensitive to
a varying than diatomic molecules. Current constraints are
for redshift , corresponding to
look-back times of 10-12.5 Gyrs, and for
, corresponding to half the age of the Universe (both at 3
statistical significance). Existing bottlenecks and prospects for future
improvement with novel instrumentation are discussed.Comment: Contribution to Workshop "High Performance Clocks in Space" at the
International Space Science Institute, Bern 201
VUV spectroscopic study of the D1Piu state of molecular deuterium
The D^1\Pi_u - X^1\Sigma_g^+ absorption system of molecular deuterium has
been re-investigated using the VUV Fourier -Transform (FT) spectrometer at the
DESIRS beamline of the synchrotron SOLEIL and photon-induced fluorescence
spectrometry (PIFS) using the 10 m normal incidence monochromator at the
synchrotron BESSY II. Using the FT spectrometer absorption spectra in the range
72 - 82 nm were recorded in quasi static gas at 100 K and in a free flowing jet
at a spectroscopic resolution of 0.50 and 0.20 cm^{-1} respectively . The
narrow Q-branch transitions, probing states of \Pi^- symmetry, were observed up
to vibrational level v = 22. The states of \Pi^+ symmetry, known to be
broadened due to predissociation and giving rise to asymmetric Beutler-Fano
resonances, were studied up to v = 18. The 10 m normal incidence beamline setup
at BESSY II was used to simultaneously record absorption, dissociation,
ionization and fluorescence decay channels from which information on the line
intensities, predissociated widths, and Fano q-parameters were extracted.
R-branch transitions were observed up to v = 23 for J = 1-3 as well as several
transitions for J = 4 and 5 up to v = 22 and 18 respectively. The Q-branch
transitions are found to weakly predissociate and were observed from v = 8 to
the final vibrational level of the state v = 23. The spectroscopic study is
supported by two theoretical frameworks. Results on the \Pi^- symmetry states
are compared to ab initio multi-channel-quantum defect theory (MQDT)
calculations, demonstrating that these calculations are accurate to within 0.5
cm^-1.Comment: 16 pages, 10 figures, 2 tables, supplemental material with an
additional tabl
- …