The ^{12}C+^{12}C fusion reaction plays a critical role in the evolution of massive stars and also strongly impacts various explosive astrophysical scenarios. The presence of resonances in this ...reaction at energies around and below the Coulomb barrier makes it impossible to carry out a simple extrapolation down to the Gamow window-the energy regime relevant to carbon burning in massive stars. The ^{12}C+^{12}C system forms a unique laboratory for challenging the contemporary picture of deep sub-barrier fusion (possible sub-barrier hindrance) and its interplay with nuclear structure (sub-barrier resonances). Here, we show that direct measurements of the ^{12}C+^{12}C fusion cross section may be made into the Gamow window using an advanced particle-gamma coincidence technique. The sensitivity of this technique effectively removes ambiguities in existing measurements made with gamma ray or charged-particle detection alone. The present cross-section data span over 8 orders of magnitude and support the fusion-hindrance model at deep sub-barrier energies.
Carbon burning at stellar energies Courtin, S.; Heine, M.; Monpribat, E. ...
Journal of physics. Conference series,
09/2023, Letnik:
2586, Številka:
1
Journal Article, Conference Proceeding
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Abstract
Fusion reactions with light nuclei play an essential role in understanding the energy production, the nucleosynthesis of chemical elements and the evolution of massive stars. The measurement ...of key fusion reactions at stellar energies is thus of interest, but highly challenging since the associated cross sections are extremely small, of the sub-nanobarn range. Among these reactions, the fusion of carbon nuclei, which drives the stellar carbon burning phase, is deeply connected with essential microscopic features such as the impact of symmetries, the access to quantum states, emerging of resonances or Pauli repulsion effects. These may manifest themselves in exceptional behaviour of the
S
-factor of this particular system and the precision of extrapolations to deep sub-barrier energies is limited. The present contribution discusses recent experimental results of the nuclear astrophysics community on the measurement of the carbon + carbon fusion reaction down to the astrophysics region. The interplay between nuclear structure, nucleosynthesis and stellar evolution is addressed.
Over the past 18 months, there has been scrutiny and controversy over the U.S. Food and Drug Administration's accelerated approval of aducanumab, a novel monoclonal antibody to treat Alzheimer's ...disease and prevent disease progression. As clinicians, educators, and advocates for our patients and caregivers impacted daily by this debilitating illness, this approval reinforces the need to maintain vigilance and awareness about emerging agents. The intent of the current article is to highlight some of the medications in Phase 3 clinical trials and share resources and updates on disease-modifying agents and their unique pharmacology.
(1), 6-10..
Local crystallographic configurations (also referred to as local micro-texture) which promote transgranular micro-crack initiation in 316LN stainless steel in low cycle fatigue are studied. Specimens ...were subjected to tension-compression with constant plastic strain amplitude, in air, at room temperature, during 5000 cycles (i.e. about 20% of the fatigue life). The first part of this work is devoted to a statistical analysis of slip marks and cracks observed at surface of one fatigued specimen using scanning electron microscope (SEM), in a region composed of about 1000 grains. 95 micro-cracks initiated along persistent slip markings detected in this region are analyzed with respect to different characteristics of grains, especially crystallographic orientation, measured using electron backscatter diffraction (EBSD). From the detailed analysis of the numerous data derived from these observations and measurements performed only at surface, the two main significant factors which are found to favour crack formation are the grain size and the orientation of the activated slip system with respect to the surface. Indeed, the mean size of grains which contain cracks is almost twice the one of the remaining grains. Moreover, for most grains in which cracks are observed, the angle between the normal to the surface and the activated Burgers vector (resp. the normal to the activated slip plane) lies in the range 30°, 50° (resp. 55°, 70°). No other characteristic was found to provide significant and direct information in order to identify initiation sites. Thus, in the second part of this work, the analysis of initiation sites is performed using additional information relative to three-dimensional (3D) aspects of the microstructure. 3D characterisation of the polycrystalline microstructure and some cracks in one fatigued specimen was achieved using serial-sectioning technique combined with SEM and EBSD. As an example, the study of one specific crack and its surrounding microstructure is presented, including crystal plasticity finite element (CPFE) simulation based on 3D mesh of the polycrystal in this studied region (composed of 386 grains). It is found that the predicted plastic slip activity is more intense within the grain where cracks have been actually observed. This study illustrates that CPFE simulations can provide consistent prediction of slip activity at surface of polycrystals, at least qualitatively, if the actual 3D microstructure is taken into account.
MedStar's Center for Successful Aging (CSA) participated in the Age-Friendly Health Systems initiative led by The John A. Hartford Foundation and the Institute for Healthcare Improvement in ...partnership with the American Hospital Association and the Catholic Health Association of the United States. This initiative focuses on bringing the 4Ms framework—What Matters, Medication, Mentation, and Mobility—to caring for older adults. A quality improvement project was conducted at the CSA to integrate the 4Ms framework into the CSA ambulatory clinical pathway. Our interventions found upward trends in patients receiving 4Ms care during their new patient visits. Positive preliminary feedback was also obtained from providers following the incorporation of the 4Ms framework in the high-risk rounds discussion. A focus on high-risk medications and deprescribing illustrated positive clinical outcomes. This ongoing interprofessional collaboration illustrates the importance of person-centered care and quality improvement to achieve Age-Friendly Health Systems status within an ambulatory practice.
Journal of Gerontological Nursing, 46
(10), 7–11.
Lifetimes or lifetime limits of a small number of excited states of the sulfur isotopes with mass numbers A=35, 36, 37, and 38 have been measured using the differential recoil-distance method. The ...isotopes of sulfur were populated in binary grazing reactions initiated by a beam of 36S ions of energy 225 MeV incident on a thin 208Pb target which was mounted in the Cologne plunger apparatus. The combination of the PRISMA magnetic spectrometer and an early implementation of the AGATA γ-ray tracking array was used to detect γ rays in coincidence with projectile-like nuclear species. Lifetime measurements of populated states were measured within the range from about 1 to 100 ps. The number of states for which lifetime measurements or lifetime limits were possible was limited by statistics. For 35S, the lifetime was determined for the first 1/2+ state at 1572 keV; the result is compared with a previous published lifetime value. The lifetime of the 3− state of 36S at 4193 keV was determined and compared with earlier measurements. No previous lifetime information exists for the (6+) state at 6690 keV; a lifetime measurement with large associated error was made in the present work. For 37S, the states for which lifetime limits were established were those at 646 keV with Jπ=3/2− and at 2776 keV with Jπ=11/2−; there are no previously published lifetime values for excited states of 37S. Finally, a lifetime limit was established for the Jπ=(6+) state of 38S at 3675 keV; no lifetime information exists for this state in the literature. Measured lifetime values were compared with the results of state-of-the-art shell-model calculations based on the PSDPF, SDPF-U, and FSU effective interactions. In addition, nuclear magnetic-dipole and electric-quadrupole moments, branching ratios, mixing ratios, and electromagnetic transition rates, where available, have been compared with shell-model values. The current work suffers from poor statistics; nevertheless, lifetime values and limits have been possible, allowing a useful discussion of the ability of state-of-the-art shell-model calculations to reproduce the experimental results.
TRP channels play a central role in the transduction of thermal and nociceptive stimuli by free nerve endings. Most of the research on these channels has been conducted in vitro or in vivo in ...nonhuman animals and translation of these results to humans must account for potential experimental biases and interspecific differences. This study aimed at evaluating the involvement of TRPM8, TRPA1 and TRPV1 channels in the transduction of heat and cold stimuli by the human thermonociceptive system. For this purpose, we evaluated the effects of topical agonists of these 3 channels (menthol, cinnamaldehyde and capsaicin) on the event-related brain potentials (ERPs) elicited by phasic thermal stimuli (target temperatures: 10°C, 42°C, and 60°C) selected to activate cold Aδ thermoreceptors, warm sensitive C thermoreceptors and heat sensitive Aδ polymodal nociceptors. Sixty-four participants were recruited, 16 allocated to each agonist solution group (20% menthol, 10% cinnamaldehyde, .025% capsaicin and 1% capsaicin). Participants were treated sequentially with the active solution on one forearm and vehicle only on the other forearm for 20 minutes. Menthol decreased the amplitude and increased the latency of cold and heat ERPs. Cinnamic aldehyde decreased the amplitude and increased the latency of heat but not cold ERPs. Capsaicin decreased the amplitude and increased the latency of heat ERPs and decreased the amplitude of the N2P2 complex of the cold ERPs without affecting the earlier N1 wave or the latencies of the peaks. These findings are compatible with previous evidence indicating that TRPM8 is involved in innocuous cold transduction and that TRPV1 and TRPA1 are involved in noxious heat transduction in humans. PERSPECTIVE: By chemically modulating TRPM8, TRPA1 and TRPV1 reactivity (key molecules in the transduction of temperature) and assessing how this affected EEG responses to the activation of cold thermoreceptors and heat nociceptors, we aimed at confirming the role of these channels in a functional healthy human model.
Purpose
To develop a prototype website to collect patient-reported outcomes in outpatient clinical oncology and link the data with the electronic medical record (EMR).
Methods
A multidisciplinary ...Research Network, including experts in outcomes research, clinical oncology, nursing, social work, information technology, EMRs, behavioral science, decision science, clinical trials, law, and a cancer survivor, was formed to design the prototype website. The Research Network developed the initial website specifications, elicited feedback from patients (
n
= 20) and clinicians (
n
= 7), constructed the website, and conducted usability testing (
n
= 10).
Results
Clinicians reported that the website could improve clinical practice if it was not burdensome and were most interested in tracking change over time. Patients were interested in using the website because of the potential to facilitate communication with their clinicians. Patients emphasized the importance of short and simple surveys and a user-friendly interface. The PatientViewpoint website was designed to meet these specifications. Usability testing suggested that patients had few problems accessing and using the site.
Conclusions
Preliminary reports from clinicians and patients suggest that a website to collect PROs and link them with the EMR could help improve the quality of cancer care. Further pilot-testing will evaluate the use, usefulness, and acceptability of PatientViewpoint.
•As stimulation surface increases, cold and warm detection thresholds decrease.•As stimulation surface increases, the detection process becomes less uncertain.•This reflects a compression of the ...psychometric function towards baseline values.•The detection of brief cooling seem less uncertain than that of warming.
Cold and warm stimuli delivered over a larger skin area tend to be more easily detected/elicit stronger sensations, a phenomenon referred to as spatial summation. The aim of the present study was to clarify how stimulation area affects thermal detection processes by evaluating whether increasing the stimulation area simply reduces the detection threshold or also reduces the uncertainty of the detection process.
Psychometric functions were fitted to the detection performance of 16 healthy subjects. Stimuli (duration: 200 ms; rate of change: 300 °C/s) were delivered to the volar forearm using a Peltier-effect contact thermode and three different stimulation surfaces (23 mm2, 69 mm2, and 116 mm). Stimulation intensities were selected trial-by-trial by the psi marginal method to optimize estimation of slope and threshold parameters of the psychometric function. The raw data (100 stimulus–response pairs per subject per surface and per modality) was used to fit group-level hierarchical models of cold and warm detection, allowing to assess the effect of stimulation surface and account for inter-individual variability.
Increasing stimulation area led to a compression of the psychometric function towards baseline skin temperature (reduced threshold and steeper slope), suggesting that spatial summation reflects a change in the precision of the neural representation of the stimulus which in turn influences the ability of the nervous system to distinguish true stimuli from sensory noise. Regardless of area, with the stimulation settings used in this study, cold detection appeared easier than warm detection, possibly because of structural and functional differences between cold- and warm-sensitive afferents.
A predictive method for remaining component lifetime evaluation consists in integrating the crack growth law of the material considered in a finite element step-by-step process. So, as part of a ...linear elastic fracture mechanics analysis, the determination of the stress intensity factor distribution is a crucial point. The aim of the present work is to test several existing numerical techniques reported in the literature. Both the crack opening displacement extrapolation method and the
J-integral approach are applied in 2D and 3D ABAQUS finite element models. The results obtained by these various means on CT specimens and cracked round bars are in good agreement with those found in the literature. Nevertheless, since the knowledge of the field near the crack tip is not required in the energetic method, the
J-integral calculations seem to be a good technique to deal with the fatigue growth of general cracks.
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