16 research outputs found

    Constraining supernova equations of state with equilibrium constants from heavy-ion collisions

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    Cluster formation is a fundamental aspect of the equation of state (EOS) of warm and dense nuclear matter such as can be found in supernovae (SNe). Similar matter can be studied in heavy-ion collisions (HIC). We use the experimental data of Qin et al. [Phys. Rev. Lett. 108, 172701 (2012)] to test calculations of cluster formation and the role of in-medium modifications of cluster properties in SN EOSs. For the comparison between theory and experiment we use chemical equilibrium constants as the main observables. This reduces some of the systematic uncertainties and allows deviations from ideal gas behavior to be identified clearly. In the analysis, we carefully account for the differences between matter in SNe and HICs. We find that, at the lowest densities, the experiment and all theoretical models are consistent with the ideal gas behavior. At higher densities ideal behavior is clearly ruled out and interaction effects have to be considered. The contributions of continuum correlations are of relevance in the virial expansion and remain a difficult problem to solve at higher densities. We conclude that at the densities and temperatures discussed mean-field interactions of nucleons, inclusion of all relevant light clusters, and a suppression mechanism of clusters at high densities have to be incorporated in the SN EOS.Comment: 20 pages, 15 figures, v2: matches published version, only minor editorial correction

    Using Light Charged Particles to Probe the Asymmetry Dependence of the Nuclear Caloric Curve

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    Recently, we observed a clear dependence of the nuclear caloric curve on neutron-proton asymmetry N−ZA\frac{N-Z}{A} through examination of fully reconstructed equilibrated quasi-projectile sources produced in heavy ion collisions at E/A = 35 MeV. In the present work, we extend our analysis using multiple light charged particle probes of the temperature. Temperatures are extracted with five distinct probes using a kinetic thermometer approach. Additionally, temperatures are extracted using two probes within a chemical thermometer approach (Albergo method). All seven measurements show a significant linear dependence of the source temperature on the source asymmetry. For the kinetic thermometer, the strength of the asymmetry dependence varies with the probe particle species in a way which is consistent with an average emission-time ordering.Comment: 7 pages, 4 figure

    Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

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    IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

    The Feasibility and Impact of a Painted Designs Intervention on School Children’s Physical Activity

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    This is an Accepted Manuscript of an article published by Taylor & Francis in Leisure/Loisir on 16 Jun 2022, available at: http://www.tandfonline.com/doi/full/10.1080/14927713.2022.2085156.Interventions such as painted designs on school tarmacs may increase children’s physical activity during school hours. This mixed-methods study examined the influence of a painted designs (e.g., traditional games, random circles) intervention on the physical activity experiences of elementary school children. Systematic observations and accelerometer data were collected to evaluate the type and quantity of student physical activity. Interviews were used to explore teacher and student experiences. Observed physical activity was not significantly different between intervention and control schools (t(43) = 0.22, p = 0.83), and children at the intervention schools undertook less physical activity (steps, moderate, vigorous, and combined moderate-to-vigorous activity) as compared with the control school (t = 2.71- 4.35, p < 0.05). Teachers and students commented that the painted designs were confusing but held potential for inclusiveness, physical activity, and learning. Additional resources and instruction may assist in better use of painted designs for physical activity and academic learning

    Searching for states analogous to the 12^{12}C Hoyle state in heavier nuclei using the thick target inverse kinematics technique

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    Identification of alpha cluster states analogous to the 12^{12}C Hoyle state in heavier alpha-conjugate nuclei can provide tests of the existence of alpha condensates in nuclei. Such states are predicted for 16^{16}O, 20^{20}Ne, 24^{24}Mg, 28^{28}Si etc. at excitation energies slightly above the multi-alpha particle decay threshold, but have not yet been experimentally identified. The Thick Target Inverse Kinematics (TTIK) technique can be used to study the breakup of excited self-conjugate nuclei into many alpha particles. The reaction 20Ne+α{\alpha} was studied using a 20^{20}Ne beam at 12MeV/nucleon from the K150 cyclotron at Texas A&M University. The TTIK method was used to study both single α{\alpha}-particle emission and multiple α{\alpha}-particle decays. Events with alpha multiplicity up to four were analyzed. The analysis of the three α{\alpha}- particle emission data allowed the identification of the Hoyle state and other 12^{12}C excited states decaying into three alpha particles. The results are shown and compared with other data available in the literature. Although the statistics for events with alpha multiplicity four is low, the data show a structure at about 15.2 MeV that could indicate the existence in 16^{16}O of a state analogous to the 12^{12}C Hoyle state. This structure is confirmed by the re-analysis of alpha multiplicity four events from a previous experiment performed at 9.7 MeV/nucleon with a similar setup but lower granularity. Moreover, the reconstructed excitation energy of 24^{24}Mg for these events peaks at around 34 MeV, very close to the predicted excitation energy for an excited state analogous to the 12^{12}C Hoyle state in 24^{24}Mg

    Study of the yield of D-D, D-3He fusion reactions produced by the interaction of intense ultrafast laser pulses with molecular clusters

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    The interaction of intense ultrafast laser pulses with molecular clusters produces a Coulomb explosion of the clusters. In this process, the positive ions from the clusters might gain enough kinetic energy to drive nuclear reactions. An experiment to measure the yield of D-D and D-3He fusion reactions was performed at University of Texas Center for High Intensity Laser Science. Laser pulses of energy ranging from 100 to 180 J and duration 150fs were delivered by the Petawatt laser. The temperature of the energetic deuterium ions was measured using a Faraday cup, whereas the yields of the D-D reactions were measured by detecting the characteristic 2.45 MeV neutrons and 3.02 MeV protons. In order to allow the simultaneous measurement of 3He(D,p) 4He and D-D reactions, different concentrations of D2 and 3He or CD4 and 3He were mixed in the gas jet target. The 2.45 MeV neutrons from the D(D,n)3He reaction were detecteded as well as the 14.7 MeV protons from the 3He(D,p)4He reaction. The preliminary results will be shown

    Diagnostics improvement in the ABC facility and preliminary tests on laser interaction with light-atom clusters and p+11B targets

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    The diagnostics of particle flows in Inertial Confinement Fusion experiments is a delicate issue, due to the fast timescales and to the strong radiative electromagnetic contributions. This makes the discrimination of the different particles produced by the laser-plasma interaction not trivial, and requires the use of several diagnostic techniques. We describe here the diagnostics improvement in the ABC facility. They will provide more detailed analysis of microwave fields and particles originating from the interaction of laser with targets foreseen for future experiments

    Rapid decrease of fragment emission time in the range of 3-5 MeV/u excitation energy

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    Multifragment emission processes from highly excited nuclei produced in 40Ar+197Au reactions at incident energies of 30 and 60 McV/u are compared. At the lowest bombarding energy and 3.3 MeV/u excitation energy, the composite system decay process supports the hypothesis of long-lived equilibrated nuclei decaying by successive binary splittings. For excited nuclei around 5 MeV/u, the depletion observed at small relative angles in the correlation functions is interpreted as the result of a strong reduction in the fragment emission time scale.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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