444 research outputs found
Radiofrequency catheter ablation in a child with Wolff-Parkinson-White syndrome and congenitally corrected transposition of the great arteries
The case is presented of a five-year-old boy with Wolff-Parkinson-White syndrome, who had
undergone three surgical palliations because of congenitally corrected transposition of the great
arteries, ventricular septal defect and pulmonary trunk near-atresia. Successful and uncomplicated
radiofrequency catheter ablation of an accessory pathway located across the systemic
atrioventricular valve ring was performed. The procedure was motivated by forthcoming corrective
surgery, which would preclude venous access to the heart. This case emphasizes the
need for precise timing of ablative therapy in such patients and shows that surgery itself may
facilitate catheter ablation. (Cardiol J 2007; 14: 500-503
Precision Measurement of 11Li moments: Influence of Halo Neutrons on the 9Li Core
The electric quadrupole moment and the magnetic moment of the 11Li halo
nucleus have been measured with more than an order of magnitude higher
precision than before, |Q| = 33.3(5)mb and mu=3.6712(3)mu_N, revealing a
8.8(1.5)% increase of the quadrupole moment relative to that of 9Li. This
result is compared to various models that aim at describing the halo
properties. In the shell model an increased quadrupole moment points to a
significant occupation of the 1d orbits, whereas in a simple halo picture this
can be explained by relating the quadrupole moments of the proton distribution
to the charge radii. Advanced models so far fail to reproduce simultaneously
the trends observed in the radii and quadrupole moments of the lithium
isotopes.Comment: 4 pages, 4 figures, 1 tabl
Determination of the photodisintegration reaction rates involving charged particles: systematical calculations and proposed measurements based on Extreme Light Infrastructure - Nuclear Physics (ELI-NP)
Photodisintegration reaction rates involving charged particles are of
relevance to the p-process nucleosynthesis that aims at explaining the
production of the stable neutron-deficient nuclides heavier than iron. In this
study, the cross sections and astrophysical rates of (g,p) and (g,a) reactions
for about 3000 target nuclei with 10<Z<100 ranging from stable to proton
dripline nuclei are computed. To study the sensitivity of the calculations to
the optical model potentials (OMPs), both the phenomenological Woods-Saxon and
the microscopic folding OMPs are taken into account. The systematic comparisons
show that the reaction rates, especially for the (g,a) reaction, are
dramatically influenced by the OMPs. Thus the better determination of the OMP
is crucial to reduce the uncertainties of the photodisintegration reaction
rates involving charged particles. Meanwhile, a gamma-beam facility at ELI-NP
is being developed, which will open new opportunities to experimentally study
the photodisintegration reactions of astrophysics interest. Considering both
the important reactions identified by the nucleosynthesis studies and the
purpose of complementing the experimental results for the reactions involving
p-nuclei, the measurements of six (g,p) and eight (g,a) reactions based on the
gamma-beam facility at ELI-NP and the ELISSA detector for the charged particles
detection are proposed, and the GEANT4 simulations are correspondingly
performed. The minimum required energies of the gamma-beam to measure these
reactions are estimated. It is shown that the direct measurements of these
photonuclear reactions within the Gamow windows at T_9=2.5 for p-process are
fairly feasible and promising at ELI-NP. The expected experimental results will
be used to constrain the OMPs of the charged particles, which can eventually
reduce the uncertainties of the reaction rates for the p-process
nucleosynthesis.Comment: 14 pages, 8 figures, Phys. Rev. C accepte
Spins, Electromagnetic Moments, and Isomers of 107-129Cd
The neutron-rich isotopes of cadmium up to the N=82 shell closure have been
investigated by high-resolution laser spectroscopy. Deep-UV excitation at 214.5
nm and radioactive-beam bunching provided the required experimental
sensitivity. Long-lived isomers are observed in 127Cd and 129Cd for the first
time. One essential feature of the spherical shell model is unambiguously
confirmed by a linear increase of the 11/2- quadrupole moments. Remarkably,
this mechanism is found to act well beyond the h11/2 shell
In-beam fast-timing measurements in 103,105,107Cd
Fast-timing measurements were performed recently in the region of the
medium-mass 103,105,107Cd isotopes, produced in fusion evaporation reactions.
Emitted gamma-rays were detected by eight HPGe and five LaBr3:Ce detectors
working in coincidence. Results on new and re-evaluated half-lives are
discussed within a systematic of transition rates. The states in
103,105,107Cd are interpreted as arising from a single-particle excitation. The
half-life analysis of the states in 103,105,107Cd shows no change in
the single-particle transition strength as a function of the neutron number
Zabieg ablacji prądem o wysokiej częstotliwości u dziecka z zespołem Wolffa-Parkinsona-White’a oraz wrodzonym skorygowanym przełożeniem wielkich pni tętniczych
W niniejszej pracy przedstawiono przypadek kliniczny 5-letniego chłopca chorującego na zespół
Wolffa-Parkinsona-White’a, który dotychczas przeszedł trzy paliatywne operacje kardiochirurgiczne
z powodu wrodzonego skorygowanego przełożenia wielkich pni tętniczych, otworu
w przegrodzie międzykomorowej oraz niepełnej atrezji pnia płucnego. Wykonano ablację prądem
o wysokiej częstotliwości drogi dodatkowej zlokalizowanej w poprzek pierścienia systemowej
zastawki przedsionkowo-komorowej. Zabieg przebiegał bez powikłań i zakończył się sukcesem.
Czas wykonania zabiegu przyspieszono ze względu na zaplanowany kolejny kardiochirurgiczny
zabieg paliatywny, który wykluczyłby dożylny dostęp do jam mięśnia sercowego. Opis
tego przypadku podnosi ważną kwestię precyzyjnego określenia czasu wykonania zabiegu
ablacyjnego u takich chorych oraz ukazuje fakt, że zabieg kardiochirurgiczny sam w sobie
może ułatwić zabieg ablacyjny. (Folia Cardiologica Excerpta 2008; 3: 50-54
Magnetic Moment of the Fragmentation Aligned 61Fe(9/2)+ Isomer
We report on the g factor measurement of the isomer in (). The isomer was produced and spin-aligned via a projectile-fragmentation
reaction at intermediate energy, the Time Dependent Perturbed Angular
Distribution (TDPAD) method being used for the measurement of the g factor. For
the first time, due to significant improvements of the experimental technique,
an appreciable residual alignment of the isomer has been observed, allowing a
precise determination of its g factor: . Comparison of the
experimental g factor with shell-model and mean field calculations confirms the
spin and parity assignments and suggests the onset of deformation due
to the intrusion of Nilsson orbitals emerging from the .Comment: 4 figures. Submitted to Phys. Rev. Let
Photonuclear spectroscopy with the ELIADE array at ELI-NP
The Extreme Light Infrastructure – Nuclear Physics in BucharestM˘agurele, Romania, is a major European undertaking with the aim of constructing a facility that can produce the worlds highest intensity laser beams as well as unique high-brilliance, narrow-bandwidth gamma-ray beams using laser-based inverse Compton scattering. One of the main instruments being constructed for the nuclear physics and applications with high-brilliance gamma-beams research activity is the ELIADE detector array of eight segmented HPGe clover detectors. Using the nuclear resonance fluorescence technique this setup will provide us with access to several nuclear observables like spins, parities, level widths, and branching ratios in the decay. From these observables we expect to draw conclusions about, for example, nuclear dipole response, properties of pygmy resonance and collective scissors mode excitations, parity violation in nuclear excitations, and matrix elements
for neutrinoless double-beta decay, among other topics. The uniqueness of the environment in which ELIADE will operate presents several challenges in the design and construction of the array. In this contribution we will present some of these challenges and how these challenges are overcome
Electromagnetic character of the competitive -decay from Ba
Second-order processes in physics is a research topic focusing attention from
several fields worldwide including, for example, non-linear quantum
electrodynamics with high-power lasers, neutrinoless double- decay, and
stimulated atomic two-photon transitions. For the electromagnetic nuclear
interaction, the observation of the competitive double- decay from
Ba has opened up the nuclear structure field for detailed
investigation of second-order processes through the manifestation of
off-diagonal nuclear polarizability. Here we confirm this observation with an
significance, and an improved value on the double-photon versus
single-photon branching ratio as . Our results, however,
contradict the conclusions from the original experiment, where the decay was
interpreted to be dominated by a quadrupole-quadrupole component. Here, we find
a substantial enhancement in the energy distribution consistent with a
dominating octupole-dipole character and a rather small quadrupole-quadrupole
element in the decay, hindered due to an evolution of the internal nuclear
structure. The implied strongly hindered double-photon branching in
Ba opens up the possibility of the double-photon branching as
a feasible tool for nuclear-structure studies on off-diagonal polarizability in
nuclei where this hindrance is not present.Comment: 12 pages, 5 figures, 2 tabel
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