688 research outputs found
Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter
The Thorium-229 isotope features a nuclear isomer state with an extremely low
energy. The currently most accepted energy value, 7.8 +- 0.5 eV, was obtained
from an indirect measurement using a NASA x-ray microcalorimeter with an
instrumental resolution 26 eV. We study, how state-of-the-art magnetic metallic
microcalorimeters with an energy resolution down to a few eV can be used to
measure the isomer energy. In particular, resolving the 29.18 keV doublet in
the \gamma-spectrum following the \alpha-decay of Uranium-233, corresponding to
the decay into the ground and isomer state, allows to measure the isomer
transition energy without additional theoretical input parameters, and increase
the energy accuracy. We study the possibility of resolving the 29.18 keV line
as a doublet and the dependence of the attainable precision of the energy
measurement on the signal and background count rates and the instrumental
resolution.Comment: 32 pages, 8 figures, eq. (3) correcte
Chemical Composition by Neutron Activation Analysis (INAA) of Neo-Assyrian Palace Ware from Iraq, Syria and Israel
Neo-Assyrian Palace Ware is an 8th-7th century B.C.E. fine-ware which originated in Northern Mesopotamia and spread throughout the greater Levant. The mechanism by which Palace Ware moved across the Neo-Assyrian imperial landscape (trade or local imitation/emulation) is of great archaeological interest. This dataset provides chemical compositional data, generated using instrumental neutron activation analysis (INAA), for Palace Ware vessels from Nimrud and Nineveh, in the Assyrian imperial core (Iraq), Dūr-Katlimmu, in one of the annexed provinces (Syria), and Tell Jemmeh, located outside the Neo-Assyrian provincial system (Israel)
The INSEN Experience, by INSEN Chairs
As a feature of this issue, we asked INSEN chairs to share their thoughts about what the organization has meant to them as they led this network of colleagues in the mission of improving nuclear security education and training at institutions and organizations around the world.
Below are their stories. The chairs describe their paths to INSEN leadership, the organization’s work, challenges, and successes, and how the experience of leading INSEN affected their professional and personal lives. IJNS thanks each of the authors contributing to this collaborative article.
Every chair has done a tremendous job in their tenure as INSEN’s leader—and we, the membership and all who have benefitted from their dedication and expertise, are deeply grateful. We look forward to INSEN’s next decade under the leadership of colleagues and friends like these
Cervical spine injuries in facial fracture patients - injury mechanism and fracture type matter
Evidence supports the notion that craniofacial fractures are significant predictors of cervical spine injuries (CSIs), but some debate remains on the injury mechanism of co-existing CSIs in craniofacial fractures and the relationship between CSI and specific facial fractures. In this retrospective study, we aim to assess the incidence rates of specific facial fracture types as well as other important variables and their relationship with CSIs. The primary outcome variable, CSI, and several predictor variables, including facial fracture type, were evaluated with logistic regression analyses. Of 2919 patients, the total CSI incidence rate was 3.0%. Rates of CSI in patients with isolated mandibular fractures (OR 0.26 CI 0.10, 0.63; p = 0.006) were lower than those previously reported, whereas isolated nasal fractures were strongly associated with CSI (OR 2.67 CI 1.36, 5.22; p = 0.004). Patients with concomitant cranial injuries were twice as likely to have CSI (OR 2.00, CI 1.22, 3.27; p = 0.006). Even though there is a strong occurrence rate of CSIs in patients with cranial injuries, clinicians should be aware that patients presenting with isolated facial fractures are at significant risk for sustaining CSIs also. (C) 2021 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.Peer reviewe
Blunt cerebrovascular injuries in the craniofacial fracture population - Are we screening the right patients?
Current knowledge of blunt cerebrovascular injuries (BCVIs) in craniomaxillofacial fracture (CMF) patients is limited. The purpose of this study was to determine the occurrence of BCVIs in patients with all types of CMF. This retrospective study included CMF patients in a level 1 trauma centre during a 3-year period. Patients who were not imaged with computed tomography angiography and patients with mechanisms other than blunt injury were excluded. The primary outcome variable was BCVI. A total of 753 patients were included in the analysis. A BCVI was detected in 4.4% of the patients screened. BCVIs occurred in 8.7% of cranial fracture patients, 7.1% of combined craniofacial fracture patients, and 3.1% of facial fracture patients. The risk of BCVI was significantly increased in patients with isolated cranial fractures (odds ratio (OR) 2.55, 95% confidence interval (CI) 1.18?5.50; P = 0.017), those involved in motor vehicle accidents (OR 3.42, 95% CI 1.63?7.17; P = 0.001), and those sustaining high-energy injuries (OR 3.17, 95% CI 1.57?6.40; P = 0.001). BCVIs in CMF patients are relatively common in highenergy injuries. However, these injuries also occur in minor traumas. Imaging thresholds should be kept low in this patient population when BCVIs are suspected.Peer reviewe
Does postoperative orbital volume predict postoperative globe malposition after blow-out fracture reconstruction? A 6-month clinical follow-up study
Purpose: The aim of this study was to investigate the relationship between intraorbital volume change caused by orbital fracture and globe malposition (GMP) in blow-out fracture patients undergoing surgery and to clarify the significance of different radiologically detected predictors associated with GMP.Patients and methods: A 6-month prospective follow-up study of unilateral isolated orbital fractures was designed and implemented. The main outcome variable was GMP (present or absent); the secondary outcome was orientation of GMP (horizontal or vertical). The primary predictor variable was postoperative orbital volume difference determined as the difference between the fractured and non-fractured orbit (measured in milliliter and analyzed in milliliter and percentages). The explanatory variables were gender, age, treatment delay from trauma to surgery, fracture site, horizontal depth of the fracture, fracture area, maximum vertical dislocation of the fracture, and preoperative volume difference.Results: A total of 15 patients fulfilled the inclusion criteria and were followed for 6months from a larger cohort. GMP was detected in 6/15 patients (40.0%). GMP was more often present in large (2.5cm(2)) fractures (55.6%), in combined orbital fractures (50.0%), and in fractures with preoperative volume difference 2.5ml (62.5%) regardless of the postoperative volume correction. Postoperatively, patients with and without GMP displayed overcorrection of orbital volume; 4.15% corresponded to 1.15ml (with GMP) and 7.6% corresponded to 1.9ml (without GMP).Conclusion: GMP was present in large and combined orbital fractures. Clinically detectable postoperative GMP occurred despite satisfactory orbital reconstruction and overcorrection. Mild GMP, however, is not significant for the patient.</div
Does postoperative orbital volume predict postoperative globe malposition after blow-out fracture reconstruction? A 6-month clinical follow-up study
PurposeThe aim of this study was to investigate the relationship between intraorbital volume change caused by orbital fracture and globe malposition (GMP) in blow-out fracture patients undergoing surgery and to clarify the significance of different radiologically detected predictors associated with GMP.Patients and methodsA 6-month prospective follow-up study of unilateral isolated orbital fractures was designed and implemented. The main outcome variable was GMP (present or absent); the secondary outcome was orientation of GMP (horizontal or vertical). The primary predictor variable was postoperative orbital volume difference determined as the difference between the fractured and non-fractured orbit (measured in milliliter and analyzed in milliliter and percentages). The explanatory variables were gender, age, treatment delay from trauma to surgery, fracture site, horizontal depth of the fracture, fracture area, maximum vertical dislocation of the fracture, and preoperative volume difference.ResultsA total of 15 patients fulfilled the inclusion criteria and were followed for 6months from a larger cohort. GMP was detected in 6/15 patients (40.0%). GMP was more often present in large (2.5cm(2)) fractures (55.6%), in combined orbital fractures (50.0%), and in fractures with preoperative volume difference 2.5ml (62.5%) regardless of the postoperative volume correction. Postoperatively, patients with and without GMP displayed overcorrection of orbital volume; 4.15% corresponded to 1.15ml (with GMP) and 7.6% corresponded to 1.9ml (without GMP).ConclusionGMP was present in large and combined orbital fractures. Clinically detectable postoperative GMP occurred despite satisfactory orbital reconstruction and overcorrection. Mild GMP, however, is not significant for the patient.Peer reviewe
Settling the half-life of ⁶⁰Fe: fundamental for a versatile astrophysical chronometer
In order to resolve a recent discrepancy in the half-life of ⁶⁰Fe, we performed an independent measurement with a new method that determines the ⁶⁰Fe content of a material relative to Fe55 (t1/2=2.744yr) with accelerator mass spectrometry. Our result of (2.50±0.12)×10⁶yr clearly favors the recently reported value (2.62±0.04)×10⁶yr, and rules out the older result of (1.49±0.27)×10⁶yr. The present weighted mean half-life value of (2.60±0.05)×10⁶yr substantially improves the reliability as an important chronometer for astrophysical applications in the million-year time range. This includes its use as a sensitive probe for studying recent chemical evolution of our Galaxy, the formation of the early Solar System, nucleosynthesis processes in massive stars, and as an indicator of a recent nearby supernova.Part of this work was funded by the Austrian Science
Fund (FWF) Projects No. AP20434 and AI00428 (FWF
and CoDustMas, Eurogenesis via ESF)
Performance of a 229 Thorium solid-state nuclear clock
The 7.8 eV nuclear isomer transition in 229 Thorium has been suggested as an
etalon transition in a new type of optical frequency standard. Here we discuss
the construction of a "solid-state nuclear clock" from Thorium nuclei implanted
into single crystals transparent in the vacuum ultraviolet range. We
investigate crystal-induced line shifts and broadening effects for the specific
system of Calcium fluoride. At liquid Nitrogen temperatures, the clock
performance will be limited by decoherence due to magnetic coupling of the
Thorium nucleus to neighboring nuclear moments, ruling out the commonly used
Rabi or Ramsey interrogation schemes. We propose a clock stabilization based on
counting of flourescence photons and present optimized operation parameters.
Taking advantage of the high number of quantum oscillators under continuous
interrogation, a fractional instability level of 10^{-19} might be reached
within the solid-state approach.Comment: 28 pages, 9 figure
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