| 1. |
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| 2. |
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| 3. |
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| 4. |
- Enochsson, L, et al.
(författare)
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The Fenyo-Lindberg scoring system for appendicitis increases positive predictive value in fertile women - A prospective study in 455 patients randomized to either laparoscopic or open appendectomy
- 2004
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Ingår i: Surgical Endoscopy. - : Springer Science and Business Media LLC. - 0930-2794 .- 1432-2218. ; 18:10, s. 1509-1513
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Tidskriftsartikel (refereegranskat)abstract
- Background: Suspected appendicitis is one of the most common indications for acute laparotomy or laparoscopy. The negative laparotomy and laparoscopy rates are high, often in the range of 15-30%, and especially high in some groups of patients such as women of child-bearing age and young patients. Different scoring systems have been introduced in order to improve diagnostic accuracy. The aim of the present study was to analyse the outcome of the Fenyo-Lindberg scoring system in a prospectively randomized multicenter trial and to analyze how well the score performed in stratified subgroups. Methods: The variables of the Fenyo-Lindberg scoring system were collected in a prospective study comparing laparoscopic and open surgery in suspected appendicitis and with four participating centers. None of the hospitals had used the scoring system previously. Since surgeons were unfamiliar with the score, they could not use it as a diagnostic aid. When comparing the score with the clinical outcome, retrospectively, the investigators interpreting the score were blinded regarding the surgical outcome. Results: Positive predictive value (PPV) of the Fenyo-Lindberg score was higher than that of the surgeon's clinical diagnosis in the patient cohort [0.90 vs 0.79 (p < 0.001)]. The score demonstrated an improvement of PPV in women [0.83 vs 0.70 (p < 0.01)]. PPV was increased in women between 15 and 50 years of age. In women aged 15-30 years and 31-50 years PPV increased from 0.69 to 0.82 and 0.68 to 0.86, respectively (p < 0.01). Both the sensitivity (0.77) and the specificity (0.69) of the score were, however, low. Conclusion: The Fenyo-Lindberg score is an inexpensive clinical tool that may improve the diagnostic accuracy for acute appendicitis in women of childbearing age, which is a group of patients where the diagnostic accuracy usually is low and where the arsenal of diagnostic tools such Lis Computed tomography is limited because of radiation. The low specificity of the score in women of childbearing age must, however, be kept in mind.
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| 5. |
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| 6. |
- Hilling, Maria, 1973-, et al.
(författare)
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IFA Sydney 2003
- 2004
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Ingår i: Svensk skattetidning. - 0346-2218. ; , s. 18-22
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 7. |
- Korolija, D, et al.
(författare)
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Evaluation of quality of life after laparoscopic surgery: evidence-based guidelines of the European Association for Endoscopic Surgery.
- 2004
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Ingår i: Surgical Endoscopy. - : Springer Science and Business Media LLC. - 0930-2794 .- 1432-2218. ; 18:6, s. 879-897
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Tidskriftsartikel (refereegranskat)abstract
- Background Measuring health-related quality of life (QoL) after surgery is essential for decision making by patients, surgeons, and payers. The aim of this consensus conference was twofold. First, it was to determine for which diseases endoscopic surgery results in better postoperative QoL than open surgery. Second, it was to recommend QoL instruments for clinical research. Methods An expert panel selected 12 conditions in which QoL and endoscopic surgery are important. For each condition, studies comparing endoscopic and open surgery in terms of QoL were identified. The expert panel reached consensus on the relative benefits of endoscopic surgery and recommended generic and disease-specific QoL instruments for use in clinical research. Results Randomized trials indicate that QoL improves earlier after endoscopic than open surgery for gastroesophageal reflux disease (GERD), cholecystolithiasis, colorectal cancer, inguinal hernia, obesity (gastric bypass), and uterine disorders that require hysterectomy. For spleen, prostate, malignant kidney, benign colorectal, and benign non-GERD esophageal diseases, evidence from nonrandomized trials supports the use of laparoscopic surgery. However, many studies failed to collect long-term results, used nonvalidated questionnaires, or measured QoL components only incompletely. The following QoL instruments can be recommended: for benign esophageal and gallbladder disease, the GIQLI or the QOLRAD together with SF-36 or the PGWB; for obesity surgery, the IWQOL-Lite with the SF-36; for colorectal cancer, the FACT-C or the EORTC QLQ-C30/CR38; for inguinal and renal surgery, the VAS for pain with the SF-36 (or the EORTC QLQ-C30 in case of malignancy); and after hysterectomy, the SF-36 together with an evaluation of urinary and sexual function. Conclusions Laparoscopic surgery provides better postoperative QoL in many clinical situations. Researchers would improve the quality of future studies by using validated QoL instruments such as those recommended here.
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| 8. |
- Lundberg, Owe, et al.
(författare)
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Pneumoperitoneum impairs blood flow and augments tumor growth in the abdominal wall.
- 2004
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Ingår i: Surgical Endoscopy. - : Springer Science and Business Media LLC. - 0930-2794 .- 1432-2218. ; 18:2, s. 293-296
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Despite several clinical and experimental studies, the mechanisms behind the development of port site metastases in laparoscopic surgery have remained largely unknown. The current study was designed to investigate the effect of pneumoperitoneum on blood flow in the abdominal wall and its possible effects on tumor growth at this site. METHODS: A total of 40 Wistar Fu rats had a laser Doppler probe placed on their left rectus muscle and a suspension of 50,000 adenocarcinoma cells was injected into their right rectus muscle. The experimental group (n = 20) was insufflated with air at 10 mmHg for 45 min while abdominal blood flow was registered before and during insufflation and after exsufflation. The control group (n = 20) was not insufflated but the blood flow was recorded in the same manner. After 9 days, all animals were killed and the occurrence of tumor was observed. The tumors were analyzed with respect to weight and volume. RESULTS: The insufflation caused an 82% reduction in blood flow in the experimental group (p < 0.001). No reduction in blood flow was registered in the control group. Tumor nodules developed significantly more often in the insufflated group (20/20) compared to the controls (14/20) (p = 0.016). Tumor weight (p = 0.003) and volume (p < 0.001) were significantly increased in the insufflated group. CONCLUSIONS: Pneumoperitoneum seems to enhance tumor growth. It also causes a significant reduction in blood flow in the abdominal wall, which may contribute to the increased susceptibility of tumor take.
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| 9. |
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| 10. |
- Nyquist, Kerstin, et al.
(författare)
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Lekmannainflytandet i Skatteverket
- 2004
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Ingår i: Svensk Skattetidning 2004, s. 535 - 549. ; , s. 535-549
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 11. |
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| 12. |
- Veldkamp, R., et al.
(författare)
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Laparoscopic resection of colon Cancer: consensus of the European Association of Endoscopic Surgery (EAES)
- 2004
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Ingår i: Surgical endoscopy. - : Springer Science and Business Media LLC. - 1432-2218 .- 0930-2794. ; 18:8, s. 1163-85
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The European Association of Endoscopic Surgery (EAES) initiated a consensus development conference on the laparoscopic resection of colon cancer during the annual congress in Lisbon, Portugal, in June 2002. METHODS: A systematic review of the current literature was combined with the opinions, of experts in the field of colon cancer surgery to formulate evidence-based statements and recommendations on the laparoscopic resection of colon cancer. RESULTS: Advanced age, obesity, and previous abdominal operations are not considered absolute contraindications for laparoscopic colon cancer surgery. The most common cause for conversion is the presence of bulky or invasive tumors. Laparoscopic operation takes longer to perform than the open counterpart, but the outcome is similar in terms of specimen size and pathological examination. Immediate postoperative morbidity and mortality are comparable for laparoscopic and open colonic cancer surgery. The laparoscopically operated patients had less postoperative pain, better-preserved pulmonary function, earlier restoration of gastrointestinal function, and an earlier discharge from the hospital. The postoperative stress response is lower after laparoscopic colectomy. The incidence of port site metastases is <1%. Survival after laparoscopic resection of colon cancer appears to be at least equal to survival after open resection. The costs of laparoscopic surgery for colon cancer are higher than those for open surgery. CONCLUSION: Laparoscopic resection of colon cancer is a safe and feasible procedure that improves short-term outcome. Results regarding the long-term survival of patients enrolled in large multicenter trials will determine its role in general surgery.
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| 13. |
- Albert, Damien, et al.
(författare)
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A Decade with VAMDC : Results and Ambitions
- 2020
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an overview of the current status of the Virtual Atomic and Molecular Data Centre (VAMDC) e-infrastructure, including the current status of the VAMDC-connected (or to be connected) databases, updates on the latest technological development within the infrastructure and a presentation of some application tools that make use of the VAMDC e-infrastructure. We analyse the past 10 years of VAMDC development and operation, and assess their impact both on the field of atomic and molecular (A&M) physics itself and on heterogeneous data management in international cooperation. The highly sophisticated VAMDC infrastructure and the related databases developed over this long term make them a perfect resource of sustainable data for future applications in many fields of research. However, we also discuss the current limitations that prevent VAMDC from becoming the main publishing platform and the main source of A&M data for user communities, and present possible solutions under investigation by the consortium. Several user application examples are presented, illustrating the benefits of VAMDC in current research applications, which often need the A&M data from more than one database. Finally, we present our vision for the future of VAMDC.
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| 14. |
- Brooks, Morris, et al.
(författare)
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Emergence of Anyons on the Two-Sphere in Molecular Impurities
- 2021
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Recently it was shown that anyons on the two-sphere naturally arise from a system of molecular impurities exchanging angular momentum with a many-particle bath (Phys. Rev. Lett. 126, 015301 (2021)). Here we further advance this approach and rigorously demonstrate that in the experimentally realized regime the lowest spectrum of two linear molecules immersed in superfluid helium corresponds to the spectrum of two anyons on the sphere. We develop the formalism within the framework of the recently experimentally observed angulon quasiparticle.
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| 15. |
- Chung, Hyun-Kyung, et al.
(författare)
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Notes on critical assessment of theoretical calculations of atomic structure and transition probabilities
- 2013
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 1:3, s. 14-15
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Tidskriftsartikel (refereegranskat)abstract
- Atomic structure and transition probabilities are fundamental physical data required in many fields of science and technology. Atomic physics codes are freely available to other community users to generate atomic data for their interest, but the quality of these data is rarely verified. This special issue addresses estimation of uncertainties in atomic structure and transition probability calculations, and discusses methods and strategies to assess and ensure the quality of theoretical atomic data.
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| 16. |
- Clementson, Joel, et al.
(författare)
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Extreme Ultraviolet Spectra of Few-Times Ionized Tungsten for Divertor Plasma Diagnostics
- 2015
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Ingår i: Atoms. - : MDPI AG. - 2218-2004. ; 3:3, s. 407-421
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Tidskriftsartikel (refereegranskat)abstract
- The extreme ultraviolet (EUV) emission from few-times ionized tungsten atoms has been experimentally studied at the Livermore electron beam ion trap facility. The ions were produced and confined during low-energy operations of the EBIT-I electron beam ion trap. By varying the electron-beam energy from around 30-300 eV, tungsten ions in charge states expected to be abundant in tokamak divertor plasmas were excited, and the resulting EUV emission was studied using a survey spectrometer covering 120-320 angstrom. It is found that the emission strongly depends on the excitation energy; below 150 eV, it is relatively simple, consisting of strong isolated lines from a few charge states, whereas at higher energies, it becomes very complex. For divertor plasmas with tungsten impurity ions, this emission should prove useful for diagnostics of tungsten flux rates and charge balance, as well as for radiative cooling of the divertor volume. Several lines in the 194-223 angstrom interval belonging to the spectra of five- and seven-times ionized tungsten (Tm-like W vi and Ho-like W viii) were also measured using a high-resolution spectrometer.
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| 17. |
- Ekman, Jörgen, et al.
(författare)
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Validation and Implementation of Uncertainty Estimates of Calculated Transition Rates
- 2014
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 2:2, s. 215-224
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Forskningsöversikt (refereegranskat)abstract
- Uncertainties of calculated transition rates in LS-allowed electric dipole transitions in boron-like O IV and carbon-like Fe XXI are estimated using an approach in which differences in line strengths calculated in length and velocity gauges are utilized. Estimated uncertainties are compared and validated against several high-quality theoretical data sets in O IV, and implemented in large scale calculations in Fe XXI.
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| 18. |
- Fischer, Charlotte Froese, et al.
(författare)
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Core Effects on Transition Energies for 3dk Configurations in Tungsten Ions
- 2017
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- All energy levels of the 3k = 1,2,..., 8, 9, configurations for tungsten ions, computed using the GRASP2K fully relativistic code based on the variational multiconfiguration Dirac-Hartree-Fock method, are reported. Included in the calculations are valence correlation where all orbitals are considered to be valence orbitals, as well as core-valence and core-core effects from the subshells. Results are compared with other recent theory and with levels obtained from the wavelengths of lines observed in the experimental spectra. It is shown that the core correlation effects considerably reduce the disagreement with levels linked directly to observed wavelengths, but may differ significantly from the NIST levels, where an unknown shift of the levels could not be determined from experimental wavelengths. For low values of k, levels were in good agreement with relativistic many-body perturbation levels, but for, the present results were in better agreement with observation.
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| 19. |
- Gaigalas, Gediminas, et al.
(författare)
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JJ2LSJ Transformation and Unique Labeling for Energy Levels
- 2017
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- The JJ2LSJ program, which is important not only for the GRASP2K package but for the atom theory in general, is presented. The program performs the transformation of atomic state functions (ASFs) from coupled CSF basis. In addition, the program implements a procedure that assigns a unique label to all energy levels. Examples of how to use the JJ2LSJ program are given. Several cases are presented where there is a unique labeling problem.
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| 20. |
- Gumberidze, Alexandre, et al.
(författare)
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Angular Distribution of Characteristic Radiation Following the Excitation of He-Like Uranium in Relativistic Collisions
- 2021
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Ingår i: Atoms. - : MDPI AG. - 2218-2004. ; 9:2
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present an experimental and theoretical study of excitation processes for the heaviest stable helium-like ion, that is, He-like uranium occurring in relativistic collisions with hydrogen and argon targets. In particular, we concentrate on angular distributions of the characteristic K alpha radiation following the K -> L excitation of He-like uranium. We pay special attention to the magnetic sub-level population of the excited 1s2l(j) states, which is directly related to the angular distribution of the characteristic K alpha radiation. We show that the experimental data can be well described by calculations taking into account the excitation by the target nucleus as well as by the target electrons. Moreover, we demonstrate for the first time an important influence of the electron-impact excitation process on the angular distributions of the K alpha radiation produced by excitation of He-like uranium in collisions with different targets.
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| 21. |
- Gustafsson, Stefan, et al.
(författare)
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Combining Multiconfiguration and Perturbation Methods : Perturbative Estimates of Core-Core Electron Correlation Contributions to Excitation Energies in Mg-Like Iron
- 2017
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- Large configuration interaction (CI) calculations can be performed if part of the interaction is treated perturbatively. To evaluate the combined CI and perturbative method, we compute excitation energies for the states in Mg-like iron. Starting from a CI calculation including valence and core-valence correlation effects, it is found that the perturbative inclusion of core-core electron correlation halves the mean relative differences between calculated and observed excitation energies. The effect of the core-core electron correlation is largest for the more excited states. The final relative differences between calculated and observed excitation energies is 0.023%, which is small enough for the calculated energies to be of direct use in line identifications in astrophysical and laboratory spectra.
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| 22. |
- Joshi, Chaitanya, et al.
(författare)
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Cavity-Assisted Generation of Sustainable Macroscopic Entanglement of Ultracold Gases
- 2015
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Ingår i: Atoms. - : MDPI AG. - 2218-2004. ; 3:3, s. 348-366
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Tidskriftsartikel (refereegranskat)abstract
- Prospects for reaching persistent entanglement between two spatially-separated atomic Bose-Einstein condensates are outlined. The system setup comprises two condensates loaded in an optical lattice, which, in return, is confined within a high-Q optical resonator. The system is driven by an external laser that illuminates the atoms, such that photons can scatter into the cavity. In the superradiant phase, a cavity field is established, and we show that the emerging cavity-mediated interactions between the two condensates is capable of entangling them despite photon losses. This macroscopic atomic entanglement is sustained throughout the time-evolution apart from occasions of sudden deaths/births. Using an auxiliary photon mode and coupling it to a collective quadrature of the two condensates, we demonstrate that the auxiliary mode's squeezing is proportional to the atomic entanglement, and as such, it can serve as a probe field of the macroscopic entanglement.
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| 23. |
- Jönsson, Per, et al.
(författare)
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MCDHF Calculations and Beam-Foil EUV Spectra of Boron-like Sodium Ions (Na VII)
- 2015
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 3:2, s. 195-259
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Tidskriftsartikel (refereegranskat)abstract
- Atomic data, such as wavelengths and line identifications, are necessary for many applications, especially in plasma diagnostics and for interpreting the spectra of distant astrophysical objects. The number of valence shell electrons increases the complexity of the computational problem. We have selected a five-electron ion, Na6+ (with the boron-like spectrum Na VII), for looking into the interplay of measurement and calculation. We summarize the available experimental work, perform our own extensive relativistic configuration interaction (RCI) computations based on multi-configuration Dirac–Hartree–Fock (MCDHF) wave functions, and compare the results to what is known of the level structure. We then discuss problems with databases that have begun to combine observations and computations.
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| 24. |
- Jönsson, Per, et al.
(författare)
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Special issue on critical assessment of theoretical calculations of atomic structure and transition probabilities
- 2013
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- There exist several codes in the atomic physics community to generate atomic structure and transition probabilities freely and readily distributed to researchers outside atomic physics community, in plasma, astrophysical or nuclear physics communities. Users take these atomic physics codes to generate the necessary atomic data or modify the codes for their own applications. However, there has been very little effort to validate and verify the data sets generated by non-expert users. In a recent IAEA meeting, researchers who develop the atomic physics codes met to discuss procedures to validate data sets generated by these distributed atomic physics codes. They agreed to implement and document the procedures to insure and validate code-generated data for non-experts in their codes. This special issue aims to document each code’s approach and procedure to critically assess the uncertainties of theoretical atomic data will have a broad impact, not only for the atomic physics community, but also for other communities interested in high quality atomic data.
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| 25. |
- Papoulia, Asimina, et al.
(författare)
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Coulomb (Velocity) Gauge Recommended in Multiconfiguration Calculations of Transition Data Involving Rydberg Series
- 2019
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Astronomical spectroscopy has recently expanded into the near-infrared (nIR) wavelength region, raising the demands on atomic transition data. The interpretation of the observed spectra largely relies on theoretical results, and progress towards the production of accurate theoretical data must continuously be made. Spectrum calculations that target multiple atomic states at the same time are by no means trivial. Further, numerous atomic systems involve Rydberg series, which are associated with additional difficulties. In this work, we demonstrate how the challenges in the computations of Rydberg series can be handled in large-scale multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) calculations. By paying special attention to the construction of the radial orbital basis that builds the atomic state functions, transition data that are weakly sensitive to the choice of gauge can be obtained. Additionally, we show that the Babushkin gauge should not always be considered as the preferred gauge, and that, in the computations of transition data involving Rydberg series, the Coulomb gauge could be more appropriate for the analysis of astrophysical spectra. To illustrate the above, results from computations of transitions involving Rydberg series in the astrophysically important C IV and C III ions are presented and analyzed.
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| 26. |
- Proto, Andrea, et al.
(författare)
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The Influence of Secondary Electron Emission and Electron Reflection on a Capacitively Coupled Oxygen Discharge
- 2018
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 6:4
-
Tidskriftsartikel (refereegranskat)abstract
- The one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 is applied to explore the role of secondary electron emission and electron reflection on the properties of the capacitively-coupled oxygen discharge. At low pressure (10 mTorr), drift-ambipolar heating of the electrons dominates within the plasma bulk, while at higher pressure (50 mTorr), stochastic electron heating in the sheath region dominates. Electron reflection has negligible influence on the electron energy probability function and only a slight influence on the electron heating profile and electron density. Including ion-induced secondary electron emission in the discharge model introduces a high energy tail to the electron energy probability function, enhances the electron density, lowers the electronegativity, and increases the effective electron temperature in the plasma bulk.
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| 27. |
- Thorsbro, Brian
(författare)
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Atomic Data Needs in Astrophysics: The Galactic Center “Scandium Mystery”
- 2020
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Ingår i: Atoms. - : MDPI AG. - 2218-2004. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Investigating the Galactic center offers unique insights into the buildup and history of our Galaxy and is a stepping stone to understand galaxies in a larger context. It is reasonable to expect that the stars found in the Galactic center might have a different composition compared to stars found in the local neighborhood around the Sun. It is therefore quite exciting when recently there were reports of unusual neutral scandium, yttrium, and vanadium abundances found in the Galactic center stars, compared to local neighborhood stars. To explain the scandium abundances in the Galactic center, we turn to recent laboratory measurements and theoretical calculations done on the atomic oscillator strengths of neutral scandium lines in the near infrared. We combine these with measurements of the hyper fine splitting of neutral scandium. We show how these results can be used to explain the reported unusual scandium abundances and conclude that in this respect, the environment of the Galactic center is not that different from the environment in the local neighborhood around the sun.
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| 28. |
- Vagnozzi, Sunny
(författare)
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New Solar Metallicity Measurements
- 2019
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Ingår i: Atoms. - : MDPI AG. - 2218-2004. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- In the past years, a systematic downward revision of the metallicity of the Sun has led to the solar modeling problem, namely the disagreement between predictions of standard solar models and inferences from helioseismology. Recent solar wind measurements of the metallicity of the Sun, however, provide once more an indication of a high-metallicity Sun. Because of the effects of possible residual fractionation, the derived value of the metallicity Z circle dot=0.0196 +/- 0.0014 actually represents a lower limit to the true metallicity of the Sun. However, when compared with helioseismological measurements, solar models computed using these new abundances fail to restore agreement, owing to the implausibly high abundance of refractory (Mg, Si, S, Fe) elements, which correlates with a higher core temperature and hence an overproduction of solar neutrinos. Moreover, the robustness of these measurements is challenged by possible first ionization potential fractionation processes. I will discuss these solar wind measurements, which leave the solar modeling problem unsolved.
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| 29. |
- van der Tak, F. F. S., et al.
(författare)
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The Leiden Atomic and Molecular Database (LAMDA): Current status, recent updates, and future plans
- 2020
-
Ingår i: Atoms. - : MDPI AG. - 2218-2004. ; 8:2
-
Forskningsöversikt (refereegranskat)abstract
- The Leiden Atomic and Molecular Database (LAMDA) collects spectroscopic information and collisional rate coefficients for molecules, atoms, and ions of astrophysical and astrochemical interest. We describe the developments of the database since its inception in 2005, and outline our plans for the near future. Such a database is constrained both by the nature of its uses and by the availability of accurate data: we suggest ways to improve the synergies among users and suppliers of data. We summarize some recent developments in computation of collisional cross sections and rate coefficients. We consider atomic and molecular data that are needed to support astrophysics and astrochemistry with upcoming instruments that operate in the mid-and far-infrared parts of the spectrum.
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| 30. |
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| 31. |
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| 32. |
- Böhm, Paul, et al.
(författare)
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Search for Weak Side Branches in the Electromagnetic Decay Paths of the 6526-keV 10+ Isomer in 54Fe
- 2023
-
Ingår i: Atoms. - 2218-2004. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- High-spin nuclear isomers in N≈Z nuclei between doubly magic 40Ca and 56Ni provide an excellent testing ground for the nuclear shell model and questions related to isospin symmetry breaking in the vicinity of the proton drip line. The purpose of the present study is to investigate the possibility of weak electromagnetic decay branches along the decay paths of the 6526-keV 10+ isomer in 54Fe. The isomer was strongly populated by means of the fusion-evaporation reaction 24Mg(36Ar,α2p)54?Fe. The Gammasphere array was used to detect γ-ray cascades emitted from the isomeric state. By means of γγγ coincidences, weak non-yrast decay branches can be discriminated, with the isomer’s half-life confirmed at T1/2 =363(4) ns. The yrast 6+1→2+1 E4 cross-over transition was interrogated. The observations are compared with shell-model calculations.
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| 33. |
- Jönsson, Per, et al.
(författare)
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An Introduction to Relativistic Theory as Implemented in GRASP
- 2023
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Computational atomic physics continues to play a crucial role in both increasing the understanding of fundamental physics (e.g., quantum electrodynamics and correlation) and producing atomic data for interpreting observations from large-scale research facilities ranging from fusion reactors to high-power laser systems, space-based telescopes and isotope separators. A number of different computational methods, each with their own strengths and weaknesses, is available to meet these tasks. Here, we review the relativistic multiconfiguration method as it applies to the General Relativistic Atomic Structure Package [grasp2018, C. Froese Fischer, G. Gaigalas, P. Jonsson, J. Bieron, Comput. Phys. Commun. (2018). DOI: 10.1016/j.cpc.2018.10.032]. To illustrate the capacity of the package, examples of calculations of relevance for nuclear physics and astrophysics are presented.
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| 34. |
- Jönsson, Per, et al.
(författare)
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GRASP Manual for Users
- 2023
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- grasp is a software package in Fortran 95, adapted to run in parallel under MPI, for research in atomic physics. The basic premise is that, given a wave function, any observed atomic property can be computed. Thus, the first step is always to determine a wave function. Different properties challenge the accuracy of the wave function in different ways. This software is distributed under the MIT Licence.
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| 35. |
- Jönsson, Per, et al.
(författare)
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Multiconfiguration Dirac-Hartree-Fock Calculations with Spectroscopic Accuracy : Applications to Astrophysics
- 2017
-
Ingår i: Atoms. - : MDPI. - 2218-2004. ; 5:2
-
Forskningsöversikt (refereegranskat)abstract
- Atomic data, such as wavelengths, spectroscopic labels, broadening parameters and transition rates, are necessary for many applications, especially in plasma diagnostics, and for interpreting the spectra of distant astrophysical objects. The experiment with its limited resources is unlikely to ever be able to provide a complete dataset on any atomic system. Instead, the bulk of the data must be calculated. Based on fundamental principles and well-justified approximations, theoretical atomic physics derives and implements algorithms and computational procedures that yield the desired data. We review progress and recent developments in fully-relativistic multiconfiguration Dirac-Hartree-Fock methods and show how large-scale calculations can give transition energies of spectroscopic accuracy, i.e., with an accuracy comparable to the one obtained from observations, as well as transition rates with estimated uncertainties of a few percent for a broad range of ions. Finally, we discuss further developments and challenges.
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| 36. |
- Lestinsky, Michael, et al.
(författare)
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First Experiments with CRYRING@ESR
- 2022
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Ingår i: Atoms. - : MDPI AG. - 2218-2004. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- The low-energy heavy ion storage ring CRYRING was transported from Stockholm to Darmstadt, modernized and reconfigured, and recommissioned as CRYRING@ESR. The machine is now in operation with all installations in service and is available as a user facility for experiments proposed through the SPARC collaboration. During the 2020–2022 period, we brought a number of experimental installations into service and used them to measure first data: the ultra-cold electron cooler for merged-beam electron–ion collisions, the gas jet target for atomic collisions, a next-generation microcalorimeter-based X-ray spectroscopy setup, and others. Ions can be injected either in low charge states from a local ion source through a 300 keV/u RFQ linac, or in high charge states from the GSI accelerator chain through ESR. This allows for very broad access to ions across the entire periodic table. CRYRING@ESR is able to de- or accelerate ions and cool and store beams of isotopically pure species in a desired charge state. While the analysis is still largely ongoing, the first experimental data already show that the machine reached its expected performance level, and our high expectations regarding achievable resolution in spectroscopy experiments have been fulfilled. With access to new classes of ions available through ESR injection and a new generation of experimental instrumentation, CRYRING@ESR is a unique facility for experiments with heavy, highly charged ions. Here, we will review our present setup and machine performance, discuss the data from our first commissioning experiments and briefly preview the upcoming new installations for the coming years.
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| 37. |
- Li, Jiguang, et al.
(författare)
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Re-Evaluation of the Nuclear Magnetic Octupole Moment of Bi-209
- 2022
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- We modified the Hfs92 code of the GRASP package in order to describe the magnetic octupole hyperfine interaction. To illustrate the utility of the modified code, we carried out state-of-the-art calculations of the electronic factors of the magnetic octupole hyperfine interaction constants for levels in the ground configuration of the Bi atom. The nuclear magnetic octupole moment of the Bi-209 isotope was extracted by combining old measurements of the hyperfine structures of 6p(34)S(3/2)(o) [Hull, R.; Brink, G. Phys. Rev. A 1970, 1, 685] and 2P(3/2)(o) [Landman, D.A.; Lurio, A. Phys. Rev. A 1970, 1, 1330] using the atomic-beam magnetic-resonance technique with our theoretical electronic factors. The present extracted octupole moment was consistent with all the available values but the one obtained in the single-particle nuclear shell model approximation. This observation supports the previous finding that nuclear many-body effects, such as the core polarization, significantly contribute to the nuclear magnetic octupole moment in the case of Bi-209.
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| 38. |
- Li, Yanting, et al.
(författare)
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Fine-Tuning of Atomic Energies in Relativistic Multiconfiguration Calculations
- 2023
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio calculations sometimes do not reproduce the experimentally observed energy separations at a high enough accuracy. Fine-tuning of diagonal elements of the Hamiltonian matrix is a process which seeks to ensure that calculated energy separations of the states that mix are in agreement with experiment. The process gives more accurate measures of the mixing than can be obtained in ab initio calculations. Fine-tuning requires the Hamiltonian matrix to be diagonally dominant, which is generally not the case for calculations based on jj-coupled configuration state functions. We show that this problem can be circumvented by a method that transforms the Hamiltonian in jj-coupling to a Hamiltonian in LSJ-coupling for which fine-tuning applies. The fine-tuned matrix is then transformed back to a Hamiltonian in jj-coupling. The implementation of the method into the General Relativistic Atomic Structure Package is described and test runs to validate the program operations are reported. The new method is applied to the computation of the 2s(21)S(0)-2s2p(1,3)P(1) transitions in C III and to the computation of Rydberg transitions in B I, for which the 2s(2)p(22)S(1/2) perturber enters the 2s(2)ns(2)S(1/2) series. Improved convergence patterns and results are found compared with ab initio calculations.
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| 39. |
- Li, Yanting, et al.
(författare)
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Independently Optimized Orbital Sets in GRASP : The Case of Hyperfine Structure in Li I
- 2023
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- In multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations, there is a strong coupling between the localization of the orbital set and the configuration state function (CSF) expansion used to determine it. Furthermore, it is well known that an orbital set resulting from calculations, including CSFs describing core-core correlation and other effects, which aims to lower the weighted energies of a number of targeted states as much as possible, may be inadequate for building CSFs that account for correlation effects that are energetically unimportant but decisive for computed properties, e.g., hyperfine structures or transition rates. This inadequacy can be traced in irregular or oscillating convergence patterns of the computed properties as functions of the increasing orbital set. In order to alleviate the above problems, we propose a procedure in which the orbital set is obtained by merging several separately optimized, and mutually non-orthogonal, orbital sets. This computational strategy preserves the advantages of capturing electron correlation on the total energy through the variational MCDHF method and allows to target efficiently the correlation effects on the considered property. The orbital sets that are merged are successively orthogonalized against each other to retain orthonormality. The merged orbital set is used to build CSFs that efficiently lower the energy and also adequately account for the correlation effects that are important for the property. We apply the procedure to compute the hyperfine structure constants for the 1s(2)2s (2)S1/2 and 1s(2)2p (2Po)(1/2, 3/2) states in Li-7 and show that it leads to considerably improved convergence patterns with respect to the increasing orbital set compared to standard calculations based on a single orbital set, energy optimized in the variational procedure. The perspectives of the new procedure are discussed in a broader context in the summary.
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| 40. |
- Li, Yanting, et al.
(författare)
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Performance Tests and Improvements on the rmcdhf and rci Programs of GRASP
- 2023
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- The latest published version of GRASP (General-purpose Relativistic Atomic Structure Package), i.e., GRASP2018, retains a few suboptimal subroutines/algorithms, which reflect the limited memory and file storage of computers available in the 1980s. Here we show how the efficiency of the relativistic self-consistent-field (SCF) procedure of the multiconfiguration-Dirac-Hartree-Fock (MCDHF) method and the relativistic configuration-interaction (RCI) calculations can be improved significantly. Compared with the original GRASP codes, the present modified version reduces the CPU times by factors of a few tens or more. The MPI performances for all the original and modified codes are carefully analyzed. Except for diagonalization, all computational processes show good MPI scaling.
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| 41. |
- Nahar, S. N., et al.
(författare)
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Experimental and Theoretical Study of Photoionization of Cl III
- 2023
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Ingår i: Atoms. - : MDPI AG. - 2218-2004. ; 11:2
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Tidskriftsartikel (refereegranskat)abstract
- Photoionization of Cl III ions into Cl IV was studied theoretically using the ab initio relativistic Breit-Pauli R-matrix (BPRM) method and experimentally at the Advanced Light Source (ALS) synchrotron at the Lawrence Berkeley National Laboratory. A relative-ion-yield spectrum of Cl IV was measured with a photon energy resolution of 10 meV. The theoretical study was carried out using a large wave-function expansion of 45 levels of configurations 3s(2)3p(2), 3s3p(3), 3s(2)3p3d, 3s(2)3p4s, 3s3p(2)3d, and 3p(4). The resulting spectra are complex. We have compared the observed spectrum with photoionization cross sections (sigma PI) of the ground state 3s(2)3p(3)(S-4(3/2)o) and the seven lowest excited levels 3s(2)3p(3)(D-2(5/2)o), 3s(2)3p(3)(D-2(3/2)o), 3s(2)3p(3)(P-2(3/2)o), 3s(2)3p3(P-2(1/2)o), 3s(3)p(4)((4)P5/2), 3s(3)p(4)(P-4(3/2)) and 3s3p(4)(P-4(1/2)) of Cl III, as these can generate resonances within the energy range of the experiment. We were able to identify most of the resonances as belonging to various specific initial levels within the primary Cl III ion beam. Compared to the first five levels, resonant structures in the sigma PI of excited levels of 3s3p(4) appear to have a weaker presence. We have also produced combined theoretical spectra of the levels by convolving the cross sections with a Gaussian profile of experimental width and summing them using statistical weight factors. The theoretical and experimental features show good agreement with the first five levels of Cl III. These features are also expected to elucidate the recent observed spectra of Cl III by Sloan Digital Scan Survey project.
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| 42. |
- Ryabchikova, Tatiana, et al.
(författare)
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Using Molecular Lines to Determine Carbon and Nitrogen Abundances in the Atmospheres of Cool Stars
- 2022
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous analysis of the C2 and CN molecular bands in the 5100–5200 and 7930–8100 Å spectral regions is a promising alternative for the accurate determination of the carbon (C) and nitrogen (N) abundance in the atmospheres of the solar-like stars. Practical implementation of this new method became possible after recent improvements of the molecular constants for both molecules. The new molecular data predicted the correct line strength and line positions; therefore, they were included in the Vienna Atomic Line Database (VALD), which is widely used by astronomers and spectroscopists. In this paper, we demonstrate that the molecular data analysis provides C and, in particular, N abundances consistent with those derived from the atomic lines. We illustrate this by performing the analysis for three stars. Our results provide strong arguments for using the combination of C2 and CN molecular lines for accurate nitrogen abundance determination keeping in mind the difficulties of using the N i lines in the observed spectra of the solar-like stars.
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| 43. |
- Vinbladh, Jimmy, et al.
(författare)
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Relativistic Two-Photon Matrix Elements for Attosecond Delays
- 2022
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Ingår i: Atoms. - : MDPI AG. - 2218-2004. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- The theory of one-photon ionization and two-photon above-threshold ionization is formulated for applications to heavy atoms in attosecond science by using Dirac–Fock formalism. A direct comparison of Wigner–Smith–Eisenbud delays for photoionization is made with delays from the Reconstruction of Attosecond Beating By Interference of Two-photon Transitions (RABBIT) method. Photoionization by an attosecond pulse train, consisting of monochromatic fields in the extreme ultraviolet range, is computed with many-body effects at the level of the relativistic random phase approximation (RRPA). Subsequent absorption and emission processes of infrared laser photons in RABBIT are evaluated by using static ionic potentials as well as asymptotic properties of relativistic Coulomb functions. As expected, light elements, such as argon, show negligible relativistic effects, whereas heavier elements, such a krypton and xenon, exhibit delays that depend on the fine-structure of the ionic target. The relativistic effects are notably close to ionization thresholds and Cooper minima with differences in fine-structure delays predicted to be as large as tens of attoseconds. The separability of relativistic RABBIT delays into a Wigner–Smith–Eisenbud delay and a universal continuum–continuum delay is studied with reasonable separability found for photoelectrons emitted along the laser polarization axis in agreement with prior non-relativistic results.
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| 44. |
- Tempe, Fredrik, et al.
(författare)
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Cost analysis comparing ultrasonic fundus-first and conventional laparoscopic cholecystectomy using electrocautery
- 2013
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Ingår i: Surgical Endoscopy. - : Springer Science and Business Media LLC. - 0930-2794 .- 1432-2218. ; 27:8, s. 2856-2859
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Tidskriftsartikel (refereegranskat)abstract
- Costs associated with laparoscopic fundus-first cholecystectomy using ultrasonic dissection versus a conventional laparoscopic cholecystectomy has not been compared. Adult patients subjected to elective laparoscopic cholecystectomy between June 2002 and March 2004 were randomized to either an ultrasonic fundus-first dissection or dissection from the triangle of Calot with electrocautery. Differences in direct and indirect costs related to either technique were studied. The duration of the operation and hospitalization was longer when dissection was with the conventional technique. With the ultrasonic fundus-first technique, the direct cost was 1,190 SEK lower, and the total cost, taking also the cost for sick leave into account, was 5,370 SEK lower. Both direct and indirect costs are lower with a laparoscopic fundus-first cholecystectomy using ultrasonic dissection than conventional laparoscopic cholecystectomy using electrocautery.
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| 45. |
- Videhult, Per, et al.
(författare)
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How reliable is intraoperative cholangiography as a method for detecting common bile duct stones? : A prospective population-based study on 1171 patients
- 2009
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Ingår i: Surgical Endoscopy. - : Springer Science and Business Media LLC. - 0930-2794 .- 1432-2218. ; 23:2, s. 304-12
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Although intraoperative cholangiography (IOC) is a widely used method for detecting common bile duct stones (CBDS), its accuracy has not been fully evaluated in large nonselected patient samples. The purpose of this study was to assess the sensitivity, specificity and predictive value of dynamic IOC regarding its ability to diagnose CBDS in a population-based setting, and to assess the morbidity associated with the investigation. METHODS: All patients operated on for gallstone disease between 2003 and 2005 in the county of Uppsala in Sweden, a county with a population of 302,000 in December 2004, were registered prospectively. The outcome of cholangiography was validated against the postoperative clinical course. RESULTS: 1171 patients were registered, and among these IOC was performed in 1117 patients (95%). Common bile duct stones were found in 134 patients (11%). One perforation of the common bile duct caused by the IOC catheter was recorded. Sensitivity was 97%, specificity 99%, negative predictive value 99%, positive predictive value 95%, and overall accuracy 99%. In 7 of the 134 cases where IOC indicated CBDS, no stones could be verified on exploration. In 4 of the 979 cases where IOC was normal, the clinical course indicated overlooked CBDS. CONCLUSION: Intraoperative cholangiography is a safe and accurate method for detecting common bile duct stones.
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