3,928 research outputs found
Ab initio Translationally Invariant Nonlocal One-body Densities from No-core Shell-model Theory
[Background:] It is well known that effective nuclear interactions are in
general nonlocal. Thus if nuclear densities obtained from {\it ab initio}
no-core-shell-model (NCSM) calculations are to be used in reaction
calculations, translationally invariant nonlocal densities must be available.
[Purpose:] Though it is standard to extract translationally invariant one-body
local densities from NCSM calculations to calculate local nuclear observables
like radii and transition amplitudes, the corresponding nonlocal one-body
densities have not been considered so far. A major reason for this is that the
procedure for removing the center-of-mass component from NCSM wavefunctions up
to now has only been developed for local densities. [Results:] A formulation
for removing center-of-mass contributions from nonlocal one-body densities
obtained from NCSM and symmetry-adapted NCSM (SA-NCSM) calculations is derived,
and applied to the ground state densities of He, Li, C, and
O. The nonlocality is studied as a function of angular momentum
components in momentum as well as coordinate space [Conclusions:] We find that
the nonlocality for the ground state densities of the nuclei under
consideration increases as a function of the angular momentum. The relative
magnitude of those contributions decreases with increasing angular momentum. In
general, the nonlocal structure of the one-body density matrices we studied is
given by the shell structure of the nucleus, and can not be described with
simple functional forms.Comment: 13 pages, 11 Figure
Spectral measures of small index principal graphs
The principal graph of a subfactor with finite Jones index is one of the
important algebraic invariants of the subfactor. If is the adjacency
matrix of we consider the equation . When has square
norm the spectral measure of can be averaged by using the map
, and we get a probability measure on the unit circle
which does not depend on . We find explicit formulae for this measure
for the principal graphs of subfactors with index , the
(extended) Coxeter-Dynkin graphs of type , and . The moment
generating function of is closely related to Jones' -series.Comment: 23 page
Ab initio Folding Potentials for Nucleon-Nucleus Scattering based on NCSM One-Body Densities
Calculating microscopic optical potentials for elastic nucleon-nucleus
scattering has already led to large body of work in the past. For folding
first-order calculations the nucleon-nucleon (NN) interaction and the one-body
density of the nucleus were taken as input to rigorous calculations in a
spectator expansion of the multiple scattering series.
Based on the Watson expansion of the multiple scattering series we employ a
nonlocal translationally invariant nuclear density derived from a chiral
next-to-next-to-leading order (NNLO) and the very same interaction for
consistent full-folding calculation of the effective (optical) potential for
nucleon-nucleus scattering for light nuclei.
We calculate scattering observables, such as total, reaction, and
differential cross sections as well as the analyzing power and the
spin-rotation parameter, for elastic scattering of protons and neutrons from
He, He, C, and O, in the energy regime between 100 and
200~MeV projectile kinetic energy, and compare to available data.
Our calculations show that the effective nucleon-nucleus potential obtained
from the first-order term in the spectator expansion of the multiple scattering
expansion describes experiments very well to about 60 degrees in the
center-of-mass frame, which coincides roughly with the validity of the NNLO
chiral interaction used to calculate both the NN amplitudes and the one-body
nuclear density.Comment: 10 pages, 14 figures, 1 tabl
Phase Conjugation and Negative Refraction Using Nonlinear Active Metamaterials
We present experimental demonstration of phase conjugation using nonlinear
metamaterial elements. Active split-ring resonators loaded with varactor diodes
are demonstrated theoretically to act as phase-conjugating or time-reversing
discrete elements when parametrically pumped and illuminated with appropriate
frequencies. The metamaterial elements were fabricated and shown experimentally
to produce a time reversed signal. Measurements confirm that a discrete array
of phase-conjugating elements act as a negatively-refracting time reversal RF
lens only 0.12 thick
Complementarity and the algebraic structure of 4-level quantum systems
The history of complementary observables and mutual unbiased bases is
reviewed. A characterization is given in terms of conditional entropy of
subalgebras. The concept of complementarity is extended to non-commutative
subalgebras. Complementary decompositions of a 4-level quantum system are
described and a characterization of the Bell basis is obtained.Comment: 19 page
The postfinasteride syndrome; an overview
As a 5-α reductase inhibitor, Finasteride has proven effective in ameliorating two conditions documented to be androgen dependent, namely male androgenic alopecia and benign prostatic hyperplasia. Therapeutic results are maintained as long as the drug is administered, with treatment cessation generally leading to the return of symptomatology for each condition. In addition, during the therapeutic phase, several adverse effects have been reported, some of which persist long or indefinitely after treatment cessation, known as “post-finasteride syndrome.”
Herein we present and discuss the most common finasteride side effects, along with a psycho-neuroendocrine rationale that could explain the persistence of many adverse effects after treatment cessation. Moreover, we argue that finasteride adverse effects occurring during finasteride administration should be delineated from postfinasteride side effects (encountered after treatment cessation), suggesting the need to be addressed separately within a therapeutic perspective. Until a tailored therapeutic approach of postfinasteride syndrome becomes available, we have noted that hand preference and sexual orientation seem to be useful as possible predicting factors for finasteride side effects and postfinasteride syndrome.
Finally, even though finasteride administration is considered relatively safe, literature data urges prudence. Specifically, recent studies report that some subjects receiving finasteride develop severe depressive episodes including suicidal thoughts, in part due to persistent sexual side effects
Ab initio Folding Potentials for Proton-Nucleus Scattering with NCSM Nonlocal One-Body Densities
Based on the spectator expansion of the multiple scattering series we employ a nonlocal translationally invariant nuclear density derived from a chiral next-to-next-to-leading order (NNLO) and the very same interaction for consistent full-folding calculations of the effective (optical) potential for nucleon-nucleus scattering for light nuclei
Single spin measurement using spin-orbital entanglement
Single spin measurement represents a major challenge for spin-based quantum
computation. In this article we propose a new method for measuring the spin of
a single electron confined in a quantum dot (QD). Our strategy is based on
entangling (using unitary gates) the spin and orbital degrees of freedom. An
{\em orbital qubit}, defined by a second, empty QD, is used as an ancilla and
is prepared in a known initial state. Measuring the orbital qubit will reveal
the state of the (unknown) initial spin qubit, hence reducing the problem to
the easier task of single charge measurement. Since spin-charge conversion is
done with unit probability, single-shot measurement of an electronic spin can
be, in principle, achieved. We evaluate the robustness of our method against
various sources of error and discuss briefly possible implementations.Comment: RevTeX4, 4 pages, some figs; updated to the published versio
- …