371 research outputs found
Plans for laser spectroscopy of trapped cold hydrogen-like HCI
Laser spectroscopy studies are being prepared to measure the 1s ground state
hyperfine splitting in trapped cold highly charged ions. The purpose of such
experiments is to test quantum electrodynamics in the strong electric field
regime. These experiments form part of the HITRAP project at GSI. A brief
review of the planned experiments is presented.Comment: 4 pages, 4 figures, accepted for publication (NIMB
Plans for laser spectroscopy of trapped cold hydrogen-like HCI
Laser spectroscopy studies are being prepared to measure the 1s ground state
hyperfine splitting in trapped cold highly charged ions. The purpose of such
experiments is to test quantum electrodynamics in the strong electric field
regime. These experiments form part of the HITRAP project at GSI. A brief
review of the planned experiments is presented.Comment: 4 pages, 4 figures, accepted for publication (NIMB
Plans for laser spectroscopy of trapped cold hydrogen-like HCI
Laser spectroscopy studies are being prepared to measure the 1s ground state
hyperfine splitting in trapped cold highly charged ions. The purpose of such
experiments is to test quantum electrodynamics in the strong electric field
regime. These experiments form part of the HITRAP project at GSI. A brief
review of the planned experiments is presented.Comment: 4 pages, 4 figures, accepted for publication (NIMB
Magnetic-dipole transition probabilities in B-like and Be-like ions
The magnetic-dipole transition probabilities between the fine-structure
levels (1s^2 2s^2 2p) ^2P_1/2 - ^2P_3/2 for B-like ions and (1s^2 2s 2p) ^3P_1
- ^3P_2 for Be-like ions are calculated. The configuration-interaction method
in the Dirac-Fock-Sturm basis is employed for the evaluation of the
interelectronic-interaction correction with negative-continuum spectrum being
taken into account. The 1/Z interelectronic-interaction contribution is derived
within a rigorous QED approach employing the two-time Green function method.
The one-electron QED correction is evaluated within framework of the anomalous
magnetic-moment approximation. A comparison with the theoretical results of
other authors and with available experimental data is presented
Decay rate measurement of the first vibrationally excited state of MgH in a cryogenic Paul trap
We present a method to measure the decay rate of the first excited
vibrational state of simple polar molecular ions being part of a Coulomb
crystal in a cryogenic linear Paul trap. Specifically, we have monitored the
decay of the == towards the ==
level in MgH by saturated laser excitation of the ==-== transition followed by state selective
resonance enhanced two-photon dissociation out of the == level. The technique enables the determination of decay rates, and
thus absorption strengths, with an accuracy at the few percent level.Comment: 5 pages, 4 figure
Optical spectroscopy of complex open 4-shell ions Sn-Sn
We analyze the complex level structure of ions with many-valence-electron
open [Kr] 4 sub-shells (=7-4) with ab initio
calculations based on configuration-interaction many-body perturbation theory
(CI+MBPT). Charge-state-resolved optical and extreme ultraviolet (EUV) spectra
of Sn-Sn ions were obtained using an electron beam ion trap.
Semi-empirical spectral fits carried out with the orthogonal parameters
technique and Cowan code calculations lead to 90 identifications of
magnetic-dipole transitions and the determination of 79 energy
ground-configuration levels, questioning some earlier EUV-line assignments. Our
results, the most complete data set available to date for these ground
configurations, confirm the ab initio predictive power of CI+MBPT calculations
for the these complex electronic systems.Comment: 18 pages, 5 figure
Insuficiencia mitral grave por perforación del velo mitral posterior
A 44 year-old woman developed severe respiratory failure and causes cardiopulmonary arrest and was admitted to ICU with multiorganic failure. In the following days presented fever and a new cardiac murmur. The transesophageal echocardiogram shows a perforation of the P1 segment of the posterior leaflet that causes a severe mitral regurgitation. The perforation was attributed to complicated infective endocarditis and leaded to the indication for surgical mitral valve replacement. The case is a great example to review the imaging pattern of mitral valve regurgitation.Paciente de 44 años que ingresa por insuficiencia respiratoria grave, que progresa a parada cardíaca y precisa reanimación cardiopulmonar. Ingresa en la UCI en situación de fracaso multiorgánico. En la evolución presenta síndrome febril y soplo de nueva aparición. La ecocardiografía transesofágica demuestra una perforación del segmento P1 del velo posterior mitral que genera una insuficiencia mitral grave. Con esta lesión se llega al diagnóstico de endocarditis mitral complicada y a la indicación de cirugía de recambio valvular mitral, que no es posible por la mala situación de la paciente. El caso es un gran ejemplo para revisar las causas de perforación mitral
Closed-cycle, low-vibration 4 K cryostat for ion traps and other applications
In-vacuo cryogenic environments are ideal for applications requiring both low
temperatures and extremely low particle densities. This enables reaching long
storage and coherence times for example in ion traps, essential requirements
for experiments with highly charged ions, quantum computation, and optical
clocks. We have developed a novel cryostat continuously refrigerated with a
pulse-tube cryocooler and providing the lowest vibration level reported for
such a closed-cycle system with 1 W cooling power for a <5 K experiment. A
decoupling system suppresses vibrations from the cryocooler by three orders of
magnitude down to a level of 10 nm peak amplitudes in the horizontal plane.
Heat loads of about 40 W (at 45 K) and 1 W (at 4 K) are transferred from an
experimental chamber, mounted on an optical table, to the cryocooler through a
vacuum-insulated massive 120 kg inertial copper pendulum. The 1.4 m long
pendulum allows installation of the cryocooler in a separate, acoustically
isolated machine room. In the laser laboratory, we measured the residual
vibrations using an interferometric setup. The positioning of the 4 K elements
is reproduced to better than a few micrometer after a full thermal cycle to
room temperature. Extreme high vacuum on the mbar level is achieved.
In collaboration with the Max-Planck-Intitut f\"ur Kernphysik (MPIK), such a
setup is now in operation at the Physikalisch-Technische Bundesanstalt (PTB)
for a next-generation optical clock experiment using highly charged ions
The JNK inhibitor, SP600125, potentiates the glial response and cell death induced by methamphetamine in the mouse striatum
This study investigates the effect of the selective Jun NH2-terminal kinase 1/2 (JNK1/2) inhibitor, (SP600125) on the striatal dopamine nerve terminal loss and on the increased interleukin-15 (IL-15) expression and glial response induced by methamphetamine (METH). Mice were given repeated low doses of METH (4Â mg/kg, i.p., three times separated by 3Â h) and killed 24Â h or 7 d after the last dose. SP600125 (30Â mg/kg, i.p) was administered 30Â min before the last METH injection. Results indicate that METH produced dopaminergic axonal neurotoxicity reflected as a marked decrease in the striatal density of tyrosine hydroxylase-immunoreactive (TH-ir) fibres and dopamine transporter-immunoreactivity (DAT-ir) 24Â h after dosing. These effects were not modified by SP600125. This compound also failed to prevent the long-term loss of dopamine levels and DAT observed 7 d following METH injection. Nevertheless, SP600125 potentiated METH-induced striatal cell loss reflected by an increase in Fluoro-Jade immunostaining, cleaved capase-3 immunoreactivity and the number of terminal deoxyncleotidyl transferase-mediated dUTP nick end labelling (TUNEL) positive cells. In line with a deleterious effect of JNK1/2 inhibition, SP600125 increased the astroglial and microglial response induced by METH and interfered with drug-induced IL-15 expression. Together these data indicate that, not only does SP600125 fail to protect against the dopaminergic damage induced by METH but also, in fact, it potentiates the glial response and the non-dopaminergic striatal cell loss caused by the drug. © 2013 CINP.Peer Reviewe
- …