180 research outputs found
Isomer triggering via nuclear excitation by electron capture
Triggering of long-lived nuclear isomeric states via coupling to the atomic
shells in the process of nuclear excitation by electron capture (NEEC) is
studied. NEEC occurring in highly-charged ions can excite the isomeric state to
a triggering level that subsequently decays to the ground state. We present
total cross sections for NEEC isomer triggering considering experimentally
confirmed low-lying triggering levels and reaction rates based on realistic
experimental parameters in ion storage rings. A comparison with other isomer
triggering mechanisms shows that, among these, NEEC is the most efficient.Comment: minor changes - updated to the final version; 4 pages, 1 figur
Parity nonconservation in electron recombination of multiply charged ions
We discuss a parity nonconserving asymmetry in the cross section of KLL
dielectronic recombination of polarized electrons on the hydrogen-like ions
with . This effect is strongly enhanced because of the
near-degeneracy of doubly-excited states of opposite parity in He-like
ions. For ions with the asymmetry is of the order of . For
a level crossing takes place, leading to the PNC asymmetry of
, which is times greater than the basic strength of
the weak interaction in atoms.Comment: 11 pages, 5 figures; v.2: sign errors in Eqs.(29-32,38) corrected,
figs.4,5 and related discussion change
Isotope shift in the dielectronic recombination of three-electron ^{A}Nd^{57+}
Isotope shifts in dielectronic recombination spectra were studied for Li-like
^{A}Nd^{57+} ions with A=142 and A=150. From the displacement of resonance
positions energy shifts \delta E^{142,150}(2s-2p_1/2)= 40.2(3)(6) meV
(stat)(sys)) and \delta E^{142,150}(2s-2p_3/2) = 42.3(12)(20) meV of 2s-2p_j
transitions were deduced. An evaluation of these values within a full QED
treatment yields a change in the mean-square charge radius of ^{142,150}\delta
= -1.36(1)(3) fm^2. The approach is conceptually new and combines the
advantage of a simple atomic structure with high sensitivity to nuclear size.Comment: 10 pages, 3 figures, accepted for publication in Physical Review
Letter
Molecular dynamics study of accelerated ion-induced shock waves in biological media
We present a molecular dynamics study of the effects of carbon- and iron-ion induced shock waves in DNA duplexes in liquid water. We use the CHARMM force field implemented within the MBN Explorer simulation package to optimize and equilibrate DNA duplexes in liquid water boxes of different sizes and shapes. The translational and vibrational degrees of freedom of water molecules are excited according to the energy deposited by the ions and the subsequent shock waves in liquid water are simulated. The pressure waves generated are studied and compared with an analytical hydrodynamics model which serves as a benchmark for evaluating the suitability of the simulation boxes. The energy deposition in the DNA backbone bonds is also monitored as an estimation of biological damage, something which is not possible with the analytical model
Clinical outcomes resulting from telemedicine interventions: a systematic review
BACKGROUND: The use of telemedicine is growing, but its efficacy for achieving comparable or improved clinical outcomes has not been established in many medical specialties. The objective of this systematic review was to evaluate the efficacy of telemedicine interventions for health outcomes in two classes of application: home-based and office/hospital-based. METHODS: Data sources for the study included deports of studies from the MEDLINE, EMBASE, CINAHL, and HealthSTAR databases; searching of bibliographies of review and other articles; and consultation of printed resources as well as investigators in the field. We included studies that were relevant to at least one of the two classes of telemedicine and addressed the assessment of efficacy for clinical outcomes with data of reported results. We excluded studies where the service did not historically require face-to-face encounters (e.g., radiology or pathology diagnosis). All included articles were abstracted and graded for quality and direction of the evidence. RESULTS: A total of 25 articles met inclusion criteria and were assessed. The strongest evidence for the efficacy of telemedicine in clinical outcomes comes from home-based telemedicine in the areas of chronic disease management, hypertension, and AIDS. The value of home glucose monitoring in diabetes mellitus is conflicting. There is also reasonable evidence that telemedicine is comparable to face-to-face care in emergency medicine and is beneficial in surgical and neonatal intensive care units as well as patient transfer in neurosurgery. CONCLUSIONS: Despite the widespread use of telemedicine in virtually all major areas of health care, evidence concerning the benefits of its use exists in only a small number of them. Further randomized controlled trials must be done to determine where its use is most effective
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