Surprising Charge-Radius Kink in the Sc Isotopes at N=20.

Charge radii of neutron deficient ^{40}Sc and ^{41}Sc nuclei were determined using collinear laser spectroscopy. With the new data, the chain of Sc charge radii extends below the neutron magic number N=20 and shows a pronounced kink, generally taken as a signature of a shell closure, but one notably absent in the neighboring Ca, K, and Ar isotopic chains. Theoretical models that explain the trend at N=20 for the Ca isotopes cannot reproduce this puzzling behavior.

Ab initio predictions link the neutron skin of 208Pb to nuclear forces.

Heavy atomic nuclei have an excess of neutrons over protons, which leads to the formation of a neutron skin whose thickness is sensitive to details of the nuclear force. This links atomic nuclei to properties of neutron stars, thereby relating objects that differ in size by orders of magnitude. The nucleus 208Pb is of particular interest because it exhibits a simple structure and is experimentally accessible. However, computing such a heavy nucleus has been out of reach for ab initio theory. By combining advances in quantum many-body methods, statistical tools and emulator technology, we make quantitative predictions for the properties of 208Pb starting from nuclear forces that are consistent with symmetries of low-energy quantum chromodynamics. We explore 109 different nuclear force parameterizations via history matching, confront them with data in select light nuclei and arrive at an importance-weighted ensemble of interactions. We accurately reproduce bulk properties of 208Pb and determine the neutron skin thickness, which is smaller and more precise than a recent extraction from parity-violating electron scattering but in agreement with other experimental probes. This work demonstrates how realistic two- and three-nucleon forces act in a heavy nucleus and allows us to make quantitative predictions across the nuclear landscape.

Early detection of complications in pancreas transplants by microdialysis catheters, an observational feasibility study.

BACKGROUND: Despite advances in immunosuppression and surgical technique, pancreas transplantation is encumbered with a high rate of complication and graft losses. Particularly, venous graft thrombi occur relatively frequently and are rarely detected before the transplant is irreversibly damaged. METHODS: To detect complications early, when the grafts are potentially salvageable, we placed microdialysis catheters anteriorly and posteriorly to the graft in a cohort of 34 consecutive patients. Glucose, lactate, pyruvate, and glycerol were measured at the bedside every 1-2 hours. RESULTS: Nine patients with graft venous thrombosis had significant lactate and lactate-to-pyruvate-ratio increases without concomitant rise in blood glucose or clinical symptoms. The median lactate in these patients was significantly higher in both catheters compared to non-events (n = 15). Out of the nine thrombi, four grafts underwent successful angiographic extraction, one did not require intervention and four grafts were irreversibly damaged and explanted. Four patients with enteric anastomosis leakages had significantly higher glycerol measurements compared to non-events. As with the venous thrombi, lactate and lactate-to-pyruvate ratio were also increased in six patients with graft surrounding hematomas. CONCLUSIONS: Bedside monitoring with microdialysis catheters is a promising surveillance modality of pancreatic grafts, but differentiating between the various pathologies proves challenging.

Global Sensitivity Analysis of Bulk Properties of an Atomic Nucleus.

We perform a global sensitivity analysis of the binding energy and the charge radius of the nucleus ^{16}O to identify the most influential low-energy constants in the next-to-next-to-leading order chiral Hamiltonian with two- and three-nucleon forces. For this purpose, we develop a subspace-projected coupled-cluster method using eigenvector continuation [Frame D. et al., Phys. Rev. Lett. 121, 032501 (2018)PRLTAO0031-900710.1103/PhysRevLett.121.032501]. With this method, we compute the binding energy and charge radius of ^{16}O at more than 10^{6} different values of the 16 low-energy constants in one hour on a standard laptop computer. For relatively small subspace projections, the root-mean-square error is about 1% compared to full-space coupled-cluster results. We find that 58(1)% of the variance in energy can be apportioned to a single contact term in the ^{3}S_{1} wave, whereas the radius depends sensitively on several low-energy constants and their higher-order correlations. The results identify the most important parameters for describing nuclear saturation and help prioritize efforts for uncertainty reduction of theoretical predictions. The achieved acceleration opens up an array of computational statistics analyses of the underlying description of the strong nuclear interaction in nuclei across the Segrè chart.

Choosing the best reconstruction technique in abdominal computed tomography: a systematic approach.

OBJECTIVE: There is uncertainty regarding the effect of iterative reconstruction (IR) techniques and other reconstruction algorithms on image quality. The aim of this study was to optimize image quality in relation to radiation dose in computed tomography (CT) liver examinations by comparing images reconstructed with different abdominal filters with and without IR. METHODS: An anthropomorphic phantom was scanned on a Toshiba Aquilion ONE CT scanner. Images at 2 different dose levels were reconstructed with 12 different body reconstruction filters, all with both filtered back-projection and Adaptive Iterative Dose Reduction 3 dimensional. Receiver operating characteristic curves were constructed. The 2 reconstruction combinations with the highest scores from the phantom study were evaluated in a second comparison of clinical images. Six liver examinations were reconstructed with both filters and evaluated using visual grading analysis. RESULTS: Two combinations of reconstruction filters and IR were the only 2 options among the 8 best images at both dose levels (area under the curve, 0.96 and 0.94 for 15 mGy as well as 0.86 and 0.84 for 10 mGy). In the patient study, one of these filters in combination with IR scored slightly higher than the other in combination with IR (mean score, 2.60 and 2.57, respectively; P = 0.56). Iterative reconstruction did not significantly increase lesion detectability for any of the filters. CONCLUSIONS: This study indicates that the preferred choice for reconstruction of CT liver examinations performed with the Toshiba Aquilion ONE should be the FC18 filter with IR, although the IR technique did not significantly improve lesion detectability and did not compensate for the dose reduction in this study.

[Angiography with 64-channel CT upon suspicion of stable coronary disease]. / Angiografi med 64-kanalers CT ved mistenkt stabil koronarsykdom.

BACKGROUND: Invasive coronary angiography is the gold standard for diagnosing coronary artery disease. CT angiography (CTA) is a non-invasive alternative that is more available and less expensive. Previous Norwegian experience with 16-channel CT has been less successful than that reported from other countries. Improved image resolution has increased expectations of a better diagnostic accuracy, but a new local assessment of the method's usefulness is needed before routine usage is implemented. MATERIAL AND METHODS: Patients with suspected stabile coronary disease, referred to invasive coronary angiography, were first assessed with 64-channel CT angiography. Patients with atrial fibrillation or previous bypass operation were not included. All patients who fulfilled the eligibility criteria were included in the study (104), but 13 who had an Agatston calcium score > or = 800 and three for whom the examinations were technically unsuccessful were excluded; the study material therefore consisted of 88 patients. We assessed the method's ability (diagnostic accuracy) to detect diameter stenoses > or = 50% in coronary segments > or = 2 mm (without stent). RESULTS: When 4% non-interpretable segments were interpreted as positive (stenotic), the sensitivity was 97%, the specificity 78% and the positive and negative predictive values were 77 and 98% on a patient level. For 50 patients who did not have significant stenosis, CTA correctly identified 39, but overestimated the degree of stenosis in 11 patients. INTERPRETATION: 64-channel CTA is best at ruling out obstructive coronary artery disease in patients with intermediate risk of such disease. Few patients with significant lesions were missed due to false negative CTA evaluations, but false positive findings are a problem in low risk populations.

Local tumor progression after radiofrequency ablation of colorectal liver metastases: evaluation of ablative margin and three-dimensional volumetric analysis.

PURPOSE: Detection of local tumor progression (LTP) after radiofrequency (RF) ablation of colorectal cancer liver metastases may facilitate repeat intervention with potential benefits for patient survival. Ablative margins 1 month after RF ablation may predict LTP, and repeated three-dimensional (3D) volumetric analysis of coagulation volume after ablation may provide earlier detection of LTP versus conventional morphologic criteria. MATERIALS AND METHODS: Seven patients with LTP and four patients without LTP after a follow-up of at least 24 months were identified. Multidetector computed tomography (CT) was performed at 1 and 3 months after RF ablation and then at 3-month intervals until 24 months. Ablative margins were determined from preablation tumor diameter and the corresponding coagulation diameter 1 month after ablation. Postablation coagulation volume was measured from 81 follow-up multidetector CT images using a seeding-based semiautomatic 3D method. RESULTS: LTP was detected at a median of 9 months (range, 6-21 months) after RF ablation. A coagulation diameter smaller than the preoperative tumor diameter was associated with LTP. Increase in coagulation volume was found in six of seven patients at the time of diagnosis of LTP by conventional morphologic criteria. CONCLUSION: Three-dimensional volumetric analysis of postablation coagulation volume is feasible for detection of LTP after RF ablation of colorectal cancer liver metastases. No advantage in early detection of LTP was found for 3D volumetric analysis compared with conventional morphologic criteria in this preliminary study. These findings may reflect a type II error caused by the limited sample size.