The data available from the A2 Collaboration at MAMI were analyzed to select the \(\gamma p\to \pi^0\eta p\) reaction on an event-by-event basis, which allows for partial-wave analyses of three-body ...final states to obtain more reliable results, compared to fits to measured distributions. These data provide the world's best statistical accuracy in the energy range from threshold to \(E_{\gamma}=1.45\) GeV, allowing a finer energy binning in the measurement of all observables needed for understanding the reaction dynamics. The results obtained for the measured observables are compared to existing models, and the impact from the new data is checked by the fit with the revised Mainz model.
The double-polarization observable \(E\) and the helicity-dependent cross sections \(\sigma_{1/2}\) and \(\sigma_{3/2}\) have been measured for the first time for single \(\pi^{0}\) photoproduction ...from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the \(\pi^0\) meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Effects from nuclear Fermi motion were removed by a kinematic reconstruction of the \(\pi^{0}N\) final state. A comparison to data measured with a free proton target showed that the absolute scale of the cross sections is significantly modified by nuclear final-state interaction (FSI) effects. However, there is no significant effect on the asymmetry \(E\) since the \(\sigma_{1/2}\) and \(\sigma_{3/2}\) components appear to be influenced in a similar way. Thus, the best approximation of the two helicity-dependent cross sections for the free neutron is obtained by combining the asymmetry \(E\) measured with quasi-free neutrons and the unpolarized cross section corrected for FSI effects under the assumption that the FSI effects are similar for neutrons and protons.
The reactions \(\gamma p\to \eta p\) and \(\gamma p\to \eta' p\) have been measured from their thresholds up to the center-of-mass energy \(W=1.96\)GeV with the tagged-photon facilities at the Mainz ...Microtron, MAMI. Differential cross sections were obtained with unprecedented accuracy, providing fine energy binning and full production-angle coverage. A strong cusp is observed in the total cross section and excitation functions for \(\eta\) photoproduction at the energies in vicinity of the \(\eta'\) threshold, \(W=1896\)MeV (\(E_\gamma=1447\)MeV). This behavior is explained in a revised \(\eta\)MAID isobar model by a significant branching of the \(N(1895)1/2^-\) nucleon resonance to both, \(\eta p\) and \(\eta' p\), confirming the existence and constraining the properties of this poorly known state.
The scalar dipole polarizabilities, \(\alpha_{E1}\) and \(\beta_{M1}\), are fundamental properties related to the internal dynamics of the nucleon. The currently accepted values of the proton ...polarizabilities were determined by fitting to unpolarized proton Compton scattering cross section data. The measurement of the beam asymmetry \(\Sigma_{3}\) in a certain kinematical range provides an alternative approach to the extraction of the scalar polarizabilities. At the Mainz Microtron (MAMI) the beam asymmetry was measured for Compton scattering below pion photoproduction threshold for the first time. The results are compared with model calculations and the influence of the experimental data on the extraction of the scalar polarizabilities is determined.
The role of adverse childhood experiences (ACEs) in predicting later adverse adult health outcomes is being widely recognized by makers of public policy. ACE questionnaires have the potential to ...identify in clinical practice unaddressed key social issues that can influence current health risks, morbidity, and early mortality. This study seeks to explore the feasibility of implementing the ACE screening of adults during routine family medicine office visits.
At 3 rural clinical practices, the 10-question ACE screen was used before visits with 111 consecutive patients of 7 clinicians. Clinician surveys about the use of the results and the effect on the visits were completed immediately after the visits. The presence of any ACE risk and "high-risk" ACE scores (≥4) were compared with clinician survey responses.
A risk of ACEs was present in 62% of patients; 22% had scores ≥4. Clinicians were more likely to have discussed ACE issues for high-risk patients (score 0-3, 36.8%; score ≥4, 83.3%; P =. 00). Clinicians also perceived that they gained new information (score 0-3, 35.6%; score ≥4, 83.3%; P = .00). Clinical care changed for a small proportion of high-risk patients, with no change in immediate referrals or plan for follow-up. In 91% of visits where a risk of ACEs was present, visit length increased by ≤5 minutes.
Incorporation of ACE screening during routine care is feasible and merits further study. ACE screening offers clinicians a more complete picture of important social determinants of health. Primary care-specific interventions that incorporate treatment of early life trauma are needed.
With the continuous development of hydropower on a global scale, stranding of freshwater fishes is of growing concern, and an understanding of the mechanisms and variables affecting fish stranding in ...hydropeaking rivers is urgently needed. In particular, a methodology is required to identify the magnitude and timing at which fish stranding occurs in relation to environmental conditions. Here, we studied fish stranding in three reaches downstream of a hydropeaking generation station in the Saskatchewan River, Saskatchewan, Canada, using an innovative remote photography approach with 45 trail cameras and traditional transect monitoring, conducting 323 transects. We observed that juvenile sport and commercial fish species are stranding at a higher proportion than small bodied fish species. The remote photography approach provided more precise fish stranding timing and associated the environmental and physical conditions with a given stranding event, but captured fewer fish and only rarely allowed species identification. The comparison of the two methodologies resulted in similar stranded fish densities, but the remote photography allowed for continuous observations whereas the transect monitoring was limited by the observer availability in the field. Remote photography allowed for additional information on the scavenging of stranded fish, with scavenging occurring on average within 240 minutes of the fish being stranded. The probability of fish stranding increased significantly with increasing water temperature and substrate particle size resulted in greater stranding on finer substrates. Our findings have important implications for hydroelectric flow management by introducing an innovative, standardized method to study the effects of hydropeaking events on fish stranding that can be applied to increase our understanding of the impacts of hydropeaking on fish communities.
•Iodine interacts with containment paint in several ways.•Some mechanistic understanding is required.•Paint aging and degradation mechanisms.•Iodine adsorption and release mechanisms.•The Severe ...Accident Research Network (SARNET) facilitates collaboration between members.
To assess the radiological consequences of a severe reactor accident, it is important to be able to predict the behaviour of iodine in containment. Some interactions between iodine and containment paint (e.g., adsorption) have been well known for a long time. However, in recent years, new phenomena have been identified that can affect the gas phase iodine concentration in the longer term (e.g., the release of molecular iodine and organic iodides from irradiated painted surfaces). Several international collaborations and organizations around the world are currently addressing different aspects of this topic, including laboratory experiments and theoretical studies (ab initio) designed to improve the mechanistic understanding of the phenomena. Knowledge of the underlying mechanisms will provide explanations for behavioural differences observed between paint types, and will support the extrapolation of laboratory results to the safety analyses of nuclear reactors.
The purpose of this paper is to present a selection of recent work performed by Severe Accident Research Network (SARNET) members regarding iodine–paint interactions and paint aging in order to improve the common understanding and better define what has still to be done in this area. The Severe Accident Research Network (SARNET) provides a framework within which members can share and discuss results.
To measure the relative biological effectiveness (RBE) of carbon ions in the rat spinal cord as a function of linear energy transfer (LET).
As an extension of a previous study, the cervical spinal ...cord of rats was irradiated with single doses of carbon ions at 6 positions of a 6-cm spread-out Bragg peak (16-99 keV/μm). The TD50 values (dose at 50% complication probability) were determined according to dose-response curves for the development of paresis grade 2 within an observation time of 300 days. The RBEs were calculated using TD50 for photons of our previous study.
Minimum latency time was found to be dose-dependent, but not significantly LET-dependent. The TD50 values for the onset of paresis grade 2 within 300 days were 19.5 ± 0.4 Gy (16 keV/μm), 18.4 ± 0.4 Gy (21 keV/μm), 17.7 ± 0.3 Gy (36 keV/μm), 16.1 ± 1.2 Gy (45 keV/μm), 14.6 ± 0.5 Gy (66 keV/μm), and 14.8 ± 0.5 Gy (99 keV/μm). The corresponding RBEs increased from 1.26 ± 0.05 (16 keV/μm) up to 1.68 ± 0.08 at 66 keV/μm. Unexpectedly, the RBE at 99 keV/μm was comparable to that at 66 keV/μm.
The data suggest a linear relation between RBE and LET at high doses for late effects in the spinal cord. Together with additional data from ongoing fractionated irradiation experiments, these data will provide an extended database to systematically benchmark RBE models for further improvements of carbon ion treatment planning.
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