This paper presents the results of an investigation into autoionizing states of atomic chromium, in the service of the resonance ionization laser ion source (RILIS): the principal ion source of the ...ISOLDE radioactive ion beam facility based at CERN. The multi-step resonance photo-ionization process enables element selective ionization which, in combination with mass separation, allows isotope specific selectivity in the production of radioactive ion beams at ISOLDE. The element selective nature of the process requires a multi-step “ionization scheme” to be developed for each element. Using the method of in-source resonance ionization spectroscopy, an optimal three-step, three-resonance photo-ionization scheme originating from the 3d5(6S)4s a7S3 atomic ground state has been developed for chromium. The scheme uses an ionizing transition to one of the 15 newly observed autoionizing states reported here. Details of the spectroscopic studies are described and the new ionization scheme is summarized.
•An investigation of multi-resonance photo-ionization schemes for Cr I•15 new autoionizing states of Cr I observed•The optimal scheme had an estimated ionization efficiency of 20%.•Laser ionized radioactive Cr ion beams now available at the CERN-ISOLDE facility
Display omitted
Norovirus is the leading cause of acute gastroenteritis in the USA. Although secondary household transmission of norovirus is frequently reported in outbreaks, little is known about specific risk ...factors for susceptibility and infectiousness in the household. Three norovirus outbreaks were investigated and data were collected on individuals exposed in the primary outbreak setting and their household members. Potential individual- and household-level risk factors for susceptibility and infectiousness were assessed using univariate and multivariate generalised linear mixed models. In the univariate models, the secondary attack rate (SAR) was significantly higher when living in a household with two or more primary cases (incidence rate ratio (IRR) = 2·1; 95% confidence interval (CI) 1·37-3·29), more than one primary case with vomiting (IRR = 1·9; CI 1·11-3·37), and at least one primary case with diarrhoea (IRR = 3·0; CI 1·46-6·01). After controlling for other risk factors in the multivariate models, the SAR was significantly higher among those living in a household with two or more primary cases (adjusted IRR = 2·0; CI 1·17-3·47) and at least one primary case with diarrhoea (adjusted IRR = 2·8; CI 1·35-5·93). These findings underscore the importance of maintaining proper hygiene and isolating ill household members to prevent norovirus transmission in the household.
Publication Ethos in the Immunogenetics community Middleton, D.; Hahn, A. B; Marsh, S. G. E.
International journal of immunogenetics,
August 2017, 2017-Aug, 2017-08-00, 20170801, Letnik:
44, Številka:
4
Journal Article
Purpose
To describe trends in emergency medicine faculty demographics, examining changes in the proportion of historically underrepresented groups including female, Black, and Latinx faculty over ...time.
Methods
Data from the Association of American Medical Colleges faculty roster (1990–2020) were used to assess the changing demographics of full‐time emergency medicine faculty. Descriptive statistics, graphic visualizations, and logistic regression modeling were used to illustrate trends in the proportion of female, Black, and Latinx faculty. Odds ratios (OR) were used to describe the estimated annual rate of change of underrepresented demographic groups.
Results
The number of full‐time emergency medicine faculty increased from 214 in 1990 to 5874 in 2020. Female emergency medicine faculty demonstrated increases in representation overall, from 35 (16.36%) in 1990 to 2247 (38.25%) in 2020, suggesting a 3% estimated annual rate of increase (OR 1.03, 95% CI 1.03–1.04) and within each academic rank. A very small positive trend was noted among Latinx faculty (n = 3, 1.40% in 1990 to n = 326, 5.55% in 2020; OR 1.01, 95% CI 1.01–1.02), whereas an even smaller, statistically insignificant increase was observed among Black emergency medicine faculty during the 31‐year study period (N = 9, 4.21% in 1990 and N = 266, 4.53% in 2020; OR 1.00, 95% CI 0.99–1.00).
Conclusions
Although female physicians have progressed toward equitable representation among academic emergency medicine faculty, no meaningful progress has been made toward racial parity. The persistent underrepresentation of Black and Latinx physicians in the academic emergency medicine workforce underscores the need for urgent structural changes to address contemporary manifestations of racism in academic medicine and beyond.
•First application of LIST target for on-line experiments at ISOLDE.•Reliable operation of LIST together with a strongly outgassing UCx target.•Suppression of isobaric contaminants by a factor of ...more than 10000 achieved.•Laser ionization efficiency of LIST improved by factor 2.5 compared to 2011 LIST.
The Laser Ion Source and Trap (LIST) provides a new mode of operation for the resonance ionization laser ion source (RILIS) at ISOLDE/CERN, reducing the amount of surface-ionized isobaric contaminants by up to four orders of magnitude. After the first successful on-line test at ISOLDE in 2011 the LIST was further improved in terms of efficiency, selectivity, and reliability through several off-line tests at Mainz University and at ISOLDE. In September 2012, the first on-line physics experiments to use the LIST took place at ISOLDE. The measurements of the improved LIST indicate more than a twofold increase in efficiency compared to the LIST of the 2011 run. The suppression of surface-ionized francium contaminants has enabled the first in-source laser spectroscopy of 217Po and 219Po.
Embryonic and fetal mortality reduce lambing rates and litter sizes, thus contributing to economic losses in the sheep industry. In the current study, the timing of late embryonic and fetal loss in ...ewes and the factors with which these losses were associated were examined. Ewes lambing and lambs born were compared with pregnancy diagnosis and counts of embryos by ultrasonography near d 25, 45, 65, or 85 of gestation. Approximately 19.9% of the ewes experienced late embryonic loss, fetal loss, or both; and 21.2% of the embryos or fetuses were lost from d 25 to term. Potential offspring were lost throughout gestation; 3.7% of embryos from d 25 to 45, 4.3% of fetuses from d 45 to 65, 3.3% from d 65 to 85, and 11.5% from d 85 to parturition; thus, approximately 3 to 4% of the potential offspring were lost for each 20-d period of pregnancy beyond d 25. A greater proportion of ewes lost one (36.7%) rather than all (20.5% single; 3.8% multiple) embryos or fetuses. The patterns of loss were similar in ewes mated during the anestrous season and the transitional period and did not vary with service period within breeding season or method of synchronization of estrus. Late embryonic or fetal losses were not related to the temperature-humidity index. Maternal serum collected near d 25, 45, 65, or 85 of gestation was assayed for concentrations of progesterone, estradiol-17β , and vascular endothelial growth factor (VEGF). The proportions of embryos or fetuses lost were associated with breed type (P < 0.05), as were concentrations of progesterone (P < 0.01), estradiol (P < 0.05), and VEGF (P < 0.01). The relationships of loss or retention of pregnancy to hormonal variables at the 4 stages studied were limited. Complete and partial losses increased rapidly as maternal progesterone at d 25 decreased below 2 ng/mL (P < 0.05). Survival of fetuses within a litter from d 25 to 65 was greater for ewes with medium concentrations of VEGF near d 25 and from d 65 to parturition was greater for ewes with high concentrations of VEGF near d 45 (P < 0.05). In summary, late embryonic or fetal losses occurred from d 25 throughout gestation and varied with breed type and with concentrations of progesterone in maternal serum on d 25.
The shape of exotic even-mass (182-190)Pb isotopes was probed by measurement of optical isotope shifts providing mean square charge radii (delta(r(2))). The experiment was carried out at the isolde ...(cern) on-line mass separator, using in-source laser spectroscopy. Small deviations from the spherical droplet model are observed, but when compared to model calculations, those are explained by high sensitivity of delta(r(2)) to beyond mean-field correlations and small admixtures of intruder configurations in the ground state. The data support the predominantly spherical shape of the ground state of the proton-magic Z=82 lead isotopes near neutron midshell (N=104).
The suppression of isobaric contaminations is of growing importance for many scientific programs using radioactive isotopes produced at isotope separation on-line (ISOL) facilities, such as ...ISOLDE-CERN. A solid tungsten proton-to-neutron converter has been used for ten years to produce neutron-rich fission fragments from an UCx target while suppressing the production of neutron-deficient isobaric contaminants. The remaining contamination is mainly produced by primary protons that are scattered by the heavy neutron converter and finally impinge on the UCx target itself. Therefore, the knowledge of the energy-dependant cross-sections of proton and neutron induced fission events is crucial in order to evaluate future converter concepts.
In this paper, an improved neutron converter prototype design is presented together with the experimentally assessed radioisotope production of Rb, Zn, Cu, Ga and In that validate the converter concept aiming at beams of higher purity neutron-rich isotopes. The experimentally derived release efficiencies for isotopes produced by the 1.4GeV protons available at ISOLDE are used to evaluate the Monte Carlo code FLUKA and the cross-section codes TALYS and ABRABLA, respectively.
A very exotic process of β-delayed fission of 180Tl is studied in detail by using resonant laser ionization with subsequent mass separation at ISOLDE (CERN). In contrast to common expectations, the ...fission-fragment mass distribution of the post-β-decay daughter nucleus 180Hg (N/Z=1.25) is asymmetric. This asymmetry is more surprising since a mass-symmetric split of this extremely neutron-deficient nucleus would lead to two 90Zr fragments, with magic N=50 and semimagic Z=40. This is a new type of asymmetric fission, not caused by large shell effects related to fragment magic proton and neutron numbers, as observed in the actinide region. The newly measured branching ratio for β-delayed fission of 180Tl is 3.6(7) × 10(-3)%, approximately 2 orders of magnitude larger than in an earlier study.
PDF
