313 research outputs found
The set of semidualizing complexes is a nontrivial metric space
We show that the set \s(R) of shift-isomorphism classes of semidualizing
complexes over a local ring admits a nontrivial metric. We investigate the
interplay between the metric and several algebraic operations. Motivated by the
dagger duality isometry, we prove the following: If are homologically
bounded below and degreewise finite -complexes such that K\lotimes_R
K\lotimes_R L is semidualizing, then is shift-isomorphic to . In
investigating the existence of nontrivial open balls in \s(R), we prove that
\s(R) contains elements that are not comparable in the reflexivity ordering
if and only if it contains at least three distinct elements.Comment: Final version (to appear in J. Algebra) has been extensively
reorganize
Vibrational excitation of diatomic molecular ions in strong-field ionization of diatomic molecules
A model based on the strong-field and Born-Oppenheimer approximations
qualitatively describes the distribution over vibrational states formed in a
diatomic molecular ion following ionization of the neutral molecule by intense
laser pulses. Good agreement is found with a recent experiment [X. Urbain et
al., Phys. Rev. Lett. 92, 163004 (2004)]. In particular, the observed deviation
from a Franck-Condon-like distribution is reproduced. Additionally, we
demonstrate control of the vibrational distribution by a variation of the peak
intensity or a change of frequency of the laser pulse.Comment: 4 pages, 4 figure
SGP28, a novel matrix glycoprotein in specific granules of human neutrophils with similarity to a human testis-specific gene product and to a rodent sperm-coating glycoprotein
AbstractA novel 28 kDa glycoprotein was purified from exocytosed material from human neutrophils and its primary structure partially determined. Degenerate oligonucleotide primers were used to amplify cDNA clones from a human bone marrow cDNA library. The deduced 245 amino acid sequence of the 2124 bp full-length cDNA showed high degrees of similarity to the deduced sequences of the human gene TPX-1 and of sperm coating glycoprotein from rat and mouse. Subcellular fractionation of human neutrophils indicated that the protein is localized in specific granules. The protein was named SGP28 (specific granule protein of 28 kDa)
Orientation-dependent ionization yields from strong-field ionization of fixed-in-space linear and asymmetric top molecules
The yield of strong-field ionization, by a linearly polarized probe pulse, is
studied experimentally and theoretically, as a function of the relative
orientation between the laser field and the molecule. Experimentally, carbonyl
sulfide, benzonitrile and naphthalene molecules are aligned in one or three
dimensions before being singly ionized by a 30 fs laser pulse centered at 800
nm. Theoretically, we address the behaviour of these three molecules. We
consider the degree of alignment and orientation and model the angular
dependence of the total ionization yield by molecular tunneling theory
accounting for the Stark shift of the energy level of the ionizing orbital. For
naphthalene and benzonitrile the orientational dependence of the ionization
yield agrees well with the calculated results, in particular the observation
that ionization is maximized when the probe laser is polarized along the most
polarizable axis. For OCS the observation of maximum ionization yield when the
probe is perpendicular to the internuclear axis contrasts the theoretical
results.Comment: 14 pages, 4 figure
Molecular orbitals and strong-field approximation
V.I. Usachenko and S.-I. Chu [Phys. Rev. A {\bf 71}, 063410 (2005)] discuss
the molecular strong-field approximation in the velocity gauge formulation and
indicate that some of our earlier velocity gauge calculations are inaccurate.
Here we comment on the results of Usachenko and Chu. First, we show that the
molecular orbitals used by Usachenko and Chu do not have the correct symmetry,
and second, that it is an oversimplification to describe the molecular orbitals
in terms of just a single linear combination of two atomic orbitals. Finally,
some values for the generalized Bessel function are given for comparison.Comment: 4 pages, 3 figure
Adaptive test – en pædagogisk udfordring og et didaktisk guldkorn
Kommentar til den aktuelle analyse “Nationale test – et eksperiment til mere end 50 millioner” iMONA, 2009(4
Strong-field ionization of atoms and molecules: The two-term saddle point method
We derive an analytical formula for the ionization rate of neutral atoms and
molecules in a strong monochromatic field. Our model is based on the
strong-field approximation with transition amplitudes calculated by an extended
saddle point method. We show that the present two-term saddle point method
reproduces even complicated structures in angular resolved photo electron
spectra
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