7 research outputs found
Influence of ion movement on the bound electron g-factor
In the relativistic description of atomic systems in external fields the
total momentum and the external electric field couple to the angular momentum
of the individual particles. Therefore, the motional state of an ion in a
particle trap influences measurements of internal observables like energy
levels or the g-factor. We calculate the resulting relativistic shift of the
Larmor frequency and the corresponding g-factor correction for a bound electron
in a hydrogen-like ion in the 1S state due to the ion moving in a Penning trap
and show that it is negligible at the current precision of measurements. We
also show that the analogous energy shift for measurements with an ion in the
ground state of a Paul trap vanishes in leading order
Nuclear Shape Effect on the g Factor of Hydrogenlike Ions
The nuclear shape correction to the g factor of a bound electron in 1S-state
is calculated for a number of nuclei in the range of charge numbers from Z=6 up
to Z=92. The leading relativistic deformation correction has been derived
analytically and also its influence on one-loop quantum electrodynamic terms
has been evaluated. We show the leading corrections to become significant for
mid-Z ions and for very heavy elements to even reach the 10^(-6) level.Comment: 4 pages, 1 figur
High-precision measurement of the atomic mass of the electron
The quest for the value of the electron's atomic mass has been subject of
continuing efforts over the last decades. Among the seemingly fundamental
constants which parameterize the Standard Model (SM) of physics and which are
thus responsible for its predictive power, the electron mass me plays a
prominent role, as it is responsible for the structure and properties of atoms
and molecules. This manifests in the close link with other fundamental
constants, such as the Rydberg constant and the fine-structure constant
{\alpha}. However, the low mass of the electron considerably complicates its
precise determination. In this work we present a substantial improvement by
combining a very accurate measurement of the magnetic moment of a single
electron bound to a carbon nucleus with a state-of-the-art calculation in the
framework of bound-state Quantum Electrodynamics. The achieved precision of the
atomic mass of the electron surpasses the current CODATA value by a factor of
13. Accordingly, the result presented in this letter lays the foundation for
future fundamental physics experiments and precision tests of the SM
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Praca recenzowana / peer-reviewed pape
Relationship between the Clinical Frailty Scale and short-term mortality in patients ≥ 80 years old acutely admitted to the ICU: a prospective cohort study.
BACKGROUND: The Clinical Frailty Scale (CFS) is frequently used to measure frailty in critically ill adults. There is wide variation in the approach to analysing the relationship between the CFS score and mortality after admission to the ICU. This study aimed to evaluate the influence of modelling approach on the association between the CFS score and short-term mortality and quantify the prognostic value of frailty in this context. METHODS: We analysed data from two multicentre prospective cohort studies which enrolled intensive care unit patients ≥ 80 years old in 26 countries. The primary outcome was mortality within 30-days from admission to the ICU. Logistic regression models for both ICU and 30-day mortality included the CFS score as either a categorical, continuous or dichotomous variable and were adjusted for patient's age, sex, reason for admission to the ICU, and admission Sequential Organ Failure Assessment score. RESULTS: The median age in the sample of 7487 consecutive patients was 84 years (IQR 81-87). The highest fraction of new prognostic information from frailty in the context of 30-day mortality was observed when the CFS score was treated as either a categorical variable using all original levels of frailty or a nonlinear continuous variable and was equal to 9% using these modelling approaches (p < 0.001). The relationship between the CFS score and mortality was nonlinear (p < 0.01). CONCLUSION: Knowledge about a patient's frailty status adds a substantial amount of new prognostic information at the moment of admission to the ICU. Arbitrary simplification of the CFS score into fewer groups than originally intended leads to a loss of information and should be avoided. Trial registration NCT03134807 (VIP1), NCT03370692 (VIP2)