Modification of surface energy in nuclear multifragmentation

Within the statistical multifragmentation model we study modifications of the surface and symmetry energy of primary fragments in the freeze-out volume. The ALADIN experimental data on multifragmentation obtained in reactions induced by high-energy projectiles with different neutron richness are analyzed. We have extracted the isospin dependence of the surface energy coefficient at different degrees of fragmentation. We conclude that the surface energy of hot fragments produced in multifragmentation reactions differs from the values extracted for isolated nuclei at low excitation. At high fragment multiplicity, it becomes nearly independent of the neutron content of the fragments.Comment: 11 pages with 13 figure

Determination of anomalous pulmonary venous return with high-pitch low-dose computed tomography in paediatric patients

Background: In this study, we aimed to image pulmonary venous return anomalies and associated cardiovascular and pulmonary abnormalities by high-pitch low-dose computed tomography (CT) in children. Materials and methods: Forty-one patients with total or partial anomalous pulmonary venous return anomalous between May 2012 and June 2019 were retrospectively reviewed. The anomalies were determined using high-pitch low-dose CT. The patients’ mean age was 3 years (6 months to 15 years), and 24 of them were female. Results: There were 10 patients with total pulmonary venous return anomalies (TPVRA) and 31 patients with partial pulmonary venous return anomalies (PPVRA). Six (60%) patients with TPVRA had the supracardiac type, 2 (20%) had the cardiac type, and 2 (20%) had the mixed type. All patients with TPVRA had a large atrial septal defect (ASD), 1 patient also had patent ductus arteriosus, and 1 patient had right cardiac hypertrophy. Forty cases of PPVRA were found in 31 patients. Twenty-seven (67%) of them were right-sided, and 13 were left-sided (33%). Twenty (65%) patients also had an additional cardiovascular anomaly (ASD in 12 patients, persistent superior vena cava in 4 patients, patent ductus arteriosus in 3 patients, and aortic coarctation in 2 patients). Of the 27 patients with right-sided PPVRA, it drained into the superior vena cava in 19 patients, the right atrium in 5 patients, and the inferior vena cava in 3 patients. In left-sided cases, the anomalous pulmonary vein drained into the left innominate vein in 9 patients, and in 4 patients, there were accessory pulmonary veins that drained into the left innominate vein. Many of the patients had additional lung anomalies, including pneumonic infiltration (n = 12), atelectasis (n = 8), and lobar emphysema (n = 5), and some of these findings coexisted. Conclusions: Anomalous pulmonary venous drains and associated cardiac and extra-cardiac anomalies can be detected reliably and quickly with high-pitch low-dose CT without sedation in paediatric patients

Common coeliacomesenteric trunk: a computed tomography radiological study

Background: There is an increasing trend for administration of invasive radiological interventions, laparoscopic surgery, and transplantation procedures in recent years, and determining the vascular variations prior to these procedures is crucially important. Coeliacomesenteric trunk (CMT) is among these variations. This study aimed to retrospectively evaluate this rare anomaly by computed tomography (CT). Materials and methods: A total of 1000 CT angiography images were analysed retrospectively, and the patients with mesenteric and coeliac arteries arising from the abdominal aorta with a single root were identified. The level that CMT arose, and its branching patterns were determined individually for all patients. Results: Ten patients (6 males and 4 females) with a mean age of 50.2 years (17–87 years) had CMT in CT images. Conclusions: The knowledge of variations in the CMT prior to vascular or laparoscopic interventions will contribute to early intervention in case of a complication, or to avoid from a potential damage

Non-invasive detection of biliary leaks using Gd-EOB-DTPA-enhanced MR cholangiography: Comparison with T2-weighted MR cholangiography

Objective: To evaluate the added role of T1-weighted (T1w) gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance cholangiography (MRC) compared with T2-weighted MRC (T2w-MRC) in the detection of biliary leaks. Methods: Ninety-nine patients with suspected biliary complications underwent routine T2w-MRC and T1w contrast-enhanced (CE) MRC using Gd-EOB-DTPA to identify biliary leaks. Two observers reviewed the image sets separately and together. MRC findings were compared with those of surgery and percutaneous transhepatic cholangiopancreatography. The sensitivity, specificity and accuracy of the techniques in identifying biliary leaks were calculated. Results: Accuracy of locating biliary leaks was superior with the combination of Gd-EOB-DTPA-enhanced MRC and T2w-MRC (P < 0.05).The mean sensitivities were 79 % vs 59 %, and the mean accuracy rates were 84 % vs 58 % for combined CE-MRC and T2w-MRC vs sole T2w-MRC. Nineteen out of 21 patients with biliary-cyst communication, 90.4 %, and 12/15 patients with post-traumatic biliary extravasations, 80 %, were detected by the combination of Gd-EOB-DTPA-enhanced MRC and T2w-MRC images, P < 0.05. Conclusions: Gd-EOB-DTPA-enhanced MRC yields information that complements T2w-MRC findings and improves the identification and localisation of the bile extravasations (84 % accuracy, 100 % specificity, P < 0.05). We recommend Gd-EOB-DTPA-enhanced MRC in addition to T2w-MRC to increase the preoperative accuracy of identifying and locating extravasations of bile. Key Points: • Magnetic resonance cholangiography (MRC) does not always detect bile leakage and cysto-biliary communications. • Gd-EOB-DTPA-enhanced MRC helps by demonstrating extravasation of contrast material into fluid collections. • Gd-EOB-DTPA-enhanced MRC also demonstrates the leakage site and bile duct injury type. • Combined Gd-EOB-DTPA-enhanced and T2w-MRC can provide comprehensive information about biliary system. • Gd-EOB-DTPA-enhanced MRC is non-invasive and does not use ionising radiation. © 2013 The Author(s)

Isospin dependent multifragmentation of relativistic projectiles

The N/Z dependence of projectile fragmentation at relativistic energies has been studied with the ALADIN forward spectrometer at the GSI Schwerionen Synchrotron (SIS). Stable and radioactive Sn and La beams with an incident energy of 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. For the interpretation of the data, calculations with the statistical multifragmentation model for a properly chosen ensemble of excited sources were performed. The parameters of the ensemble, representing the variety of excited spectator nuclei expected in a participant-spectator scenario, are determined empirically by searching for an optimum reproduction of the measured fragment-charge distributions and correlations. An overall very good agreement is obtained. The possible modification of the liquid-drop parameters of the fragment description in the hot freeze-out environment is studied, and a significant reduction of the symmetry-term coefficient is found necessary to reproduce the mean neutron-to-proton ratios /Z and the isoscaling parameters of Z<=10 fragments. The calculations are, furthermore, used to address open questions regarding the modification of the surface-term coefficient at freeze-out, the N/Z dependence of the nuclear caloric curve, and the isotopic evolution of the spectator system between its formation during the initial cascade stage of the reaction and its subsequent breakup.Comment: 23 pages, 29 figures, published in Physical Review

Symmetry energy of fragments produced in multifragmentation

Isospin properties of fragments measured in multifragmentation of 136Xe and 124Xe projectiles in mid-peripheral collisions with a lead target at 1 A GeV were studied within the statistical approach describing the liquid-gas nuclear phase transition. By analyzing the isoscaling phenomenon and the mean N-over-Z ratio of the fragments with Z=10-13 we have concluded that the symmetry energy of hot fragments produced in multifragment environment at subnuclear densities at high temperatures decreases in comparison with cold nuclei.Comment: 10 pages, 4 figures, background information on http://www-w2k.gsi.de/charms