| 1. |
- Reifarth, R., et al.
(författare)
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Nuclear astrophysics with radioactive ions at FAIR
- 2016
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 665:1
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Konferensbidrag (refereegranskat)abstract
- The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process beta-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes.
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| 2. |
- Antonov, A. N., et al.
(författare)
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The electron-ion scattering experiment ELISe at the International Facility for Antiproton and Ion Research (FAIR)-A conceptual design study
- 2011
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002 .- 0167-5087. ; 637:1, s. 60-76
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Tidskriftsartikel (refereegranskat)abstract
- The electron-ion scattering experiment ELISe is part of the installations envisaged at the new experimental storage ring at the International Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It offers an unique opportunity to use electrons as probe in investigations of the structure of exotic nuclei. The conceptual design and the scientific challenges of ELISe are presented. (C) 2011 Elsevier B.V. All rights reserved.
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| 3. |
- Sanchez-Cano, B., et al.
(författare)
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Total electron content in the Martian atmosphere : A critical assessment of the Mars Express MARSIS data sets
- 2015
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Ingår i: Journal of Geophysical Research - Space Physics. - 2169-9380 .- 2169-9402. ; 120:3, s. 2166-2182
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Tidskriftsartikel (refereegranskat)abstract
- The total electron content (TEC) is one of the most useful parameters to evaluate the behavior of the Martian ionosphere because it contains information on the total amount of free electrons, the main component of the Martian ionospheric plasma. The Mars Express Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) radar is able to derive TEC from both of its operation modes: (1) the active ionospheric sounding (AIS) mode and (2) the subsurface mode. TEC estimates from the subsurface sounding mode can be computed from the same raw data independently using different algorithms, which should yield similar results. Significant differences on the dayside, however, have been found from two of the algorithms. Moreover, both algorithms seem also to disagree with the TEC results from the AIS mode. This paper gives a critical, quantitative, and independent assessment of these discrepancies and indicates the possible uncertainty of these databases. In addition, a comparison between the results given by the empirical model of the Martian ionosphere developed by Sanchez-Cano et al. (2013) and the different data sets has been performed. The main result is that for solar zenith angles higher than 75 degrees, where the maximum plasma frequency is typically small compared with the radar frequencies, the two subsurface algorithms can be confidently used. For solar zenith angles less than 75 degrees, where the maximum plasma frequency is very close to the radar frequencies, both algorithms suffer limitations. Nevertheless, despite the solar zenith angle restrictions, the dayside TEC of one of the two algorithms is consistent with the modeled TEC.
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| 4. |
- Villalaín, C., et al.
(författare)
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Diagnostic accuracy of prenatal ultrasound in coarctation of aorta : systematic review and individual participant data meta-analysis
- 2024
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Ingår i: Ultrasound in Obstetrics and Gynecology. - 0960-7692. ; 63:4, s. 446-456
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Forskningsöversikt (refereegranskat)abstract
- Objective: To determine the diagnostic accuracy of prenatal ultrasound in detecting coarctation of the aorta (CoA). Methods: An individual participant data meta-analysis was performed to report on the strength of association and diagnostic accuracy of different ultrasound signs in detecting CoA prenatally. MEDLINE, EMBASE and CINAHL were searched for studies published between January 2000 and November 2021. Inclusion criteria were fetuses with suspected isolated CoA, defined as ventricular and/or great vessel disproportion with right dominance on ultrasound assessment. Individual participant-level data were obtained by two leading teams. PRISMA-IPD and PRISMA-DTA guidelines were used for extracting data, and the QUADAS-2 tool was used for assessing quality and applicability. The reference standard was CoA, defined as narrowing of the aortic arch, diagnosed after birth. The most commonly evaluated parameters on ultrasound, both in B-mode and on Doppler, constituted the index test. Summary estimates of sensitivity, specificity, diagnostic odds ratio (DOR) and likelihood ratios were computed using the hierarchical summary receiver-operating-characteristics model. Results: The initial search yielded 72 studies, of which 25 met the inclusion criteria. Seventeen studies (640 fetuses) were included. On random-effects logistic regression analysis, tricuspid valve/mitral valve diameter ratio > 1.4 and > 1.6, aortic isthmus/arterial duct diameter ratio < 0.7, hypoplastic aortic arch (all P < 0.001), aortic isthmus diameter Z-score of < −2 in the sagittal (P = 0.003) and three-vessel-and-trachea (P < 0.001) views, pulmonary artery/ascending aorta diameter ratio > 1.4 (P = 0.048) and bidirectional flow at the foramen ovale (P = 0.012) were independently associated with CoA. Redundant foramen ovale was inversely associated with CoA (P = 0.037). Regarding diagnostic accuracy, tricuspid valve/mitral valve diameter ratio > 1.4 had a sensitivity of 72.6% (95% CI, 48.2–88.3%), specificity of 65.4% (95% CI, 46.9–80.2%) and DOR of 5.02 (95% CI, 1.82–13.9). The sensitivity and specificity values were, respectively, 75.0% (95% CI, 61.1–86.0%) and 39.7% (95% CI, 27.0–53.4%) for pulmonary artery/ascending aorta diameter ratio > 1.4, 47.8% (95% CI, 14.6–83.0%) and 87.6% (95% CI, 27.3–99.3%) for aortic isthmus diameter Z-score of < –2 in the sagittal view and 74.1% (95% CI, 58.0–85.6%) and 62.0% (95% CI, 41.6–78.9%) for aortic isthmus diameter Z-score of < –2 in the three-vessel-and-trachea view. Hypoplastic aortic arch had a sensitivity of 70.0% (95% CI, 42.0–88.6%), specificity of 91.3% (95% CI, 78.6–96.8%) and DOR of 24.9 (95% CI, 6.18–100). The diagnostic yield of prenatal ultrasound in detecting CoA did not change significantly when considering multiple categorical parameters. Five of the 11 evaluated continuous parameters were independently associated with CoA (all P < 0.001) but all had low-to-moderate diagnostic yield. Conclusions: Several prenatal ultrasound parameters are associated with an increased risk for postnatal CoA. However, diagnostic accuracy is only moderate, even when combinations of parameters are considered.
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| 5. |
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| 6. |
- Sabater, L., et al.
(författare)
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Evidence-based guidelines for the management of exocrine pancreatic insufficiency after pancreatic surgery
- 2016
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Ingår i: Annals of Surgery. - 0003-4932 .- 1528-1140. ; 264:6, s. 949-958
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To provide evidence-based recommendations for the management of exocrine pancreatic insufficiency (EPI) after pancreatic surgery. Background: EPI is a common complication after pancreatic surgery but there is certain confusion about its frequency, optimal methods of diagnosis, and when and how to treat these patients. Methods: Eighteen multidisciplinary reviewers performed a systematic review on 10 predefined questions following the GRADE methodology. Six external expert referees reviewed the retrieved information. Members from Spanish Association of Pancreatology were invited to suggest modifications and voted for the quantification of agreement. Results: These guidelines analyze the definition of EPI after pancreatic surgery, (one question), its frequency after specific techniques and underlying disease (four questions), its clinical consequences (one question), diagnosis (one question), when and how to treat postsurgical EPI (two questions) and its impact on the quality of life (one question). Eleven statements answering those 10 questions were provided: one (9.1%) was rated as a strong recommendation according to GRADE, three (27.3%) as moderate and seven (63.6%) as weak. All statements had strong agreement. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
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| 7. |
- Schweikhard, L., et al.
(författare)
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Photodissociation of Au30+ clusters stored in a Penning trap
- 2005
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Ingår i: Eur. Phys. J. D. - : Springer Science and Business Media LLC. - 1434-6060. ; 36, s. 179-185
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Tidskriftsartikel (refereegranskat)abstract
- Ion trapping allows detailed studies of atomic clusters with various interactions and over a large range of timescales. An overview of methods at hand is given and a specific example is presented in detail where size-selected Au30+ clusters have been stored in a Penning trap and photofragmented by exposure to the third harmonic of a Nd:YAG laser. The resulting mass spectra were sampled after reaction periods varying from 10μs to 1s. The data are used to extract relative dissociation energies, which agree well with model-free values determined previously by other means, albeit with a slightly larger magnitude of the odd-even effect. Below n≃24 the relative dissociation energies extracted from the abundance spectra develop very little over the five orders of magnitude in time covered in the experiments. This behavior has been predicted, but not tested previously. Above n≃24 both spectra and dissociation energies develop odd-even effects after a storage time of 10–100 ms. Possible reasons for this behavior are discussed.
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| 8. |
- Hindell, Mark A., et al.
(författare)
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Circumpolar habitat use in the southern elephant seal : implications for foraging success and population trajectories
- 2016
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Ingår i: Ecosphere. - : Wiley. - 2150-8925 .- 2150-8925. ; 7:5
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Tidskriftsartikel (refereegranskat)abstract
- In the Southern Ocean, wide-ranging predators offer the opportunity to quantify how animals respond to differences in the environment because their behavior and population trends are an integrated signal of prevailing conditions within multiple marine habitats. Southern elephant seals in particular, can provide useful insights due to their circumpolar distribution, their long and distant migrations and their performance of extended bouts of deep diving. Furthermore, across their range, elephant seal populations have very different population trends. In this study, we present a data set from the International Polar Year project; Marine Mammals Exploring the Oceans Pole to Pole for southern elephant seals, in which a large number of instruments (N = 287) deployed on animals, encompassing a broad circum-Antarctic geographic extent, collected in situ ocean data and at-sea foraging metrics that explicitly link foraging behavior and habitat structure in time and space. Broadly speaking, the seals foraged in two habitats, the relatively shallow waters of the Antarctic continental shelf and the Kerguelen Plateau and deep open water regions. Animals of both sexes were more likely to exhibit area-restricted search (ARS) behavior rather than transit in shelf habitats. While Antarctic shelf waters can be regarded as prime habitat for both sexes, female seals tend to move northwards with the advance of sea ice in the late autumn or early winter. The water masses used by the seals also influenced their behavioral mode, with female ARS behavior being most likely in modified Circumpolar Deepwater or northerly Modified Shelf Water, both of which tend to be associated with the outer reaches of the Antarctic Continental Shelf. The combined effects of (1) the differing habitat quality, (2) differing responses to encroaching ice as the winter progresses among colonies, (3) differing distances between breeding and haul-out sites and high quality habitats, and (4) differing long-term -regional trends in sea ice extent can explain the differing population trends observed among elephant seal colonies.
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| 9. |
- López Herraiz, Joaquín, et al.
(författare)
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(e,e'p) reaction at true quasielastic kinematics in 16O, 12C, and 208Pb at JLab
- 2009
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Ingår i: La Rabida 2009, International Scientific Meeting on Nuclear Physics: Basic Concepts in Nuclear Physics : Theory Experiements and Applications - Theory Experiements and Applications. - : AIP. ; , s. 225-226
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Konferensbidrag (refereegranskat)abstract
- The reactions 16O(e,e'p) 15N, 208Pb(e,e'p) 207Tl and 12C(e,e'p) 11B were measured in experiments E00-102 and E06-007 performed at JLab (VA, USA) at true quasielastic kinematics (xB = 1) with constant energy (ω) and momentum (q) transferred over a wide pmiss range. These experiments address several open issues in nuclear structure such as the role of relativity and of long-range correlations in the description of nuclei as well as a possible dependence of the spectroscopic factors on Q2. Preliminary experimental results and theoretical predictions from a fully relativistic DWIA model carefully averaged over the experimental acceptances are shown.
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| 10. |
- Portela, E., et al.
(författare)
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Controls on Dense Shelf Water Formation in Four East Antarctic Polynyas
- 2022
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Ingår i: Journal of Geophysical Research: Oceans. - 2169-9275. ; 127:12
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Tidskriftsartikel (refereegranskat)abstract
- Coastal polynyas are key formation regions for dense shelf water (DSW) that ultimately contributes to the ventilation of the ocean abyss. However, not all polynyas form DSW. We examine how the physiographic setting, water-mass distribution and transformation, water column stratification, and sea-ice production regulate DSW formation in four East Antarctic coastal polynyas. We use a salt budget to estimate the relative contribution of sea-ice production and lateral advection to the monthly change in salinity in each polynya. DSW forms in Mackenzie polynya due to a combination of physical features (shallow water depth and a broad continental shelf) and high sea-ice production. Sea-ice formation begins early (March) in Mackenzie polynya, counteracting fresh advection and establishing a salty mixed layer in autumn that preconditions the water column for deep convection in winter. Sea-ice production is moderate in the other three polynyas, but saline DSW is not formed (a fresh variety is formed in the Barrier polynya). In the Shackleton polynya, brine rejection during winter is insufficient to overcome the very fresh autumn mixed layer. In Vincennes Bay, a strong inflow of modified Circumpolar Deep Water stratifies the water column, hindering deep convection and DSW formation. Our study highlights that DSW formation in a given polynya depends on a complex combination of factors, some of which may be strongly altered under a changing climate, with potentially important consequences for the ventilation of the deep ocean, the global meridional overturning circulation, and the transport of ocean heat to Antarctic ice shelves.
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