134 research outputs found

    Shell-model half-lives for r-process waiting point nuclei including first-forbidden contributions

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    We have performed large-scale shell-model calculations of the half-lives and neutron-branching probabilities of the r-process waiting point nuclei at the magic neutron numbers N=50, 82, and 126. The calculations include contributions from allowed Gamow-Teller and first-forbidden transitions. We find good agreement with the measured half-lives for the N=50 nuclei with charge numbers Z=28-32 and for the N=82 nuclei 129Ag and 130Cd. The contribution of forbidden transitions reduce the half-lives of the N=126 waiting point nuclei significantly, while they have only a small effect on the half-lives of the N=50 and 82 r-process nuclei.Comment: 14 pages, 17 figures, submitted to Phys. Rev.

    Using Photodynamic Therapy to Estimate Effectiveness of Innovative Combined Diclofenac and Tazaroten Therapy of Disseminated Actinic Keratosis

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    Early diagnosis and therapy of precancerous lesions and malignant tumors belong to the most challenging tasks in modern medicine. Photodynamic diagnosis can help diagnose both precancerous lesions and early carcinoma. Actinic keratosis (AK) is the most common precancerous lesion of the skin. The available data show a high effectiveness of diclofenac in treating multifocal AK. We report a case of a 52-year-old woman who complained of multiple disseminated AK lesions predominantly on the lower limbs and trunk with a significant exacerbation within the last 6 months. Due to the spreading of disease and a high number of AK foci, as well as technical problems with visiting the hospital (PDT Laboratory), photodynamic therapy was not applied. The patient was treated for 2 months with a combination of local administration of 3% diclofenac and 0.1% tazaroten and 3% diclofenac only as a half side (left-right) comparison. The effects of therapy were later clinically evaluated and verified by means of photodynamic diagnosis (PDD) directly after therapy and at a follow-up examination 3 months later. The evaluation of treatment was blinded.Treatment with diclofenac only on the right side of the body resulted in clearing of 55% of all treated lesions, which increased to 60% three months after finishing therapy. On the left side of the body, where combined therapy (diclofenac 2 times daily on uneven dates and diclofenac once a day + tazaroten once a day on even dates) was used, 77.5% pathologic lesions disappeared, but this did not increase at follow up. The treatment of multifocal, disseminated AK is a difficult task and also burdensome for the patient due to side effects like scarring or burning and itching which occur during most therapies. Combined therapy with diclofenac and tazaroten supported by PDD may improve the effects of routine treatment of AK.</p

    Time-of-flight mass measurements of neutron-rich chromium isotopes up to N = 40 and implications for the accreted neutron star crust

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    We present the mass excesses of 59-64Cr, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The mass of 64Cr is determined for the first time, with an atomic mass excess of -33.48(44) MeV. We find a significantly different two-neutron separation energy S2n trend for neutron-rich isotopes of chromium, removing the previously observed enhancement in binding at N=38. Additionally, we extend the S2n trend for chromium to N=40, revealing behavior consistent with the previously identified island of inversion in this region. We compare our results to state-of-the-art shell-model calculations performed with a modified Lenzi-Nowacki-Poves-Sieja interaction in the fp shell, including the g9/2 and d5/2 orbits for the neutron valence space. We employ our result for the mass of 64Cr in accreted neutron star crust network calculations and find a reduction in the strength and depth of electron-capture heating from the A=64 isobaric chain, resulting in a cooler than expected accreted neutron star crust. This reduced heating is found to be due to the >1-MeV reduction in binding for 64Cr with respect to values from commonly used global mass models.Comment: Accepted to Physical Review

    Large-Scale Self-Consistent Nuclear Mass Calculations

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    The program of systematic large-scale self-consistent nuclear mass calculations that is based on the nuclear density functional theory represents a rich scientific agenda that is closely aligned with the main research directions in modern nuclear structure and astrophysics, especially the radioactive nuclear beam physics. The quest for the microscopic understanding of the phenomenon of nuclear binding represents, in fact, a number of fundamental and crucial questions of the quantum many-body problem, including the proper treatment of correlations and dynamics in the presence of symmetry breaking. Recent advances and open problems in the field of nuclear mass calculations are presented and discussed.Comment: 21 pages, 5 figures, submitted to International Journal of Mass Spectrometr

    Isomeric excitation energy for 99^{99}Inm^{m} from mass spectrometry reveals constant trend next to doubly magic 100^{100}Sn

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    The excitation energy of the 1/2−^- isomer in 99^{99}In at N=50{N=50} is measured to be 671(37) keV and the mass uncertainty of the 9/2+^+ ground state is significantly reduced using the ISOLTRAP mass spectrometer at ISOLDE/CERN. The measurements exploit a major improvement in the resolution of the multi-reflection time-of-flight mass spectrometer. The results reveal an intriguing constancy of the 1/2−1/2^- isomer excitation energies in neutron-deficient indium that persists down to the N=50N = 50 shell closure, even when all neutrons are removed from the valence shell. This trend is used to test large-scale shell model, \textit{ab initio}, and density functional theory calculations. The models have difficulties describing both the isomer excitation energies and ground-state electromagnetic moments along the indium chain.Comment: 13 pages, 4 figure

    Identifying and addressing barriers to implementing core electronic health record use metrics for ambulatory care: Virtual consensus conference proceedings

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    Precise, reliable, valid metrics that are cost-effective and require reasonable implementation time and effort are needed to drive electronic health record (EHR) improvements and decrease EHR burden. Differences exist between research and vendor definitions of metrics. PROCESS:  We convened three stakeholder groups (health system informatics leaders, EHR vendor representatives, and researchers) in a virtual workshop series to achieve consensus on barriers, solutions, and next steps to implementing the core EHR use metrics in ambulatory care. CONCLUSION:  Actionable solutions identified to address core categories of EHR metric implementation challenges include: (1) maintaining broad stakeholder engagement, (2) reaching agreement on standardized measure definitions across vendors, (3) integrating clinician perspectives, and (4) addressing cognitive and EHR burden. Building upon the momentum of this workshop\u27s outputs offers promise for overcoming barriers to implementing EHR use metrics

    First g(2+) measurement on neutron-rich 72 Zn, and the high-velocity transient field technique for radioactive heavy-ion beams

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    The high-velocity transient-field (HVTF) technique was used to measure the g factor of the 2+ state of 72Zn produced as a radioactive beam. The transient-field strength was probed at high velocity in ferromagnetic iron and gadolinium hosts using 76Ge beams. The potential of the HVTF method is demonstrated and the difficulties that need to be overcome for a reliable use of the TF technique with high-Z, high-velocity radioactive beams are revealed. The polarization of K-shell vacancies at high velocity, which shows more than an order of magnitude difference between Z = 20 and Z = 30 is discussed. The g-factor measurement hints at the theoretically predicted transition in the structure of the Zn isotopes near N = 40

    Nuclear Structure Towards N=40 60Ca: In-beam gamma-ray Spectroscopy of 58,60Ti

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    Excited states in the neutron-rich N=38,36 nuclei \nuc{60}{Ti} and \nuc{58}{Ti} were populated in nucleon-removal reactions from \nuc{61}{V} projectiles at 90~MeV/nucleon. The \gamma-ray transitions from such states in these Ti isotopes were detected with the advanced \gamma-ray tracking array GRETINA and were corrected event-by-event for large Doppler shifts (v/c \sim 0.4) using the \gamma-ray interaction points deduced from online signal decomposition. The new data indicate that a steep decrease in quadrupole collectivity occurs when moving from neutron-rich N=36,38 Fe and Cr toward the Ti and Ca isotones. In fact, \nuc{58,60}{Ti} provide some of the most neutron-rich benchmarks accessible today for calculations attempting to determine the structure of the potentially doubly-magic nucleus \nuc{60}{Ca}.Comment: Accepted for publication in Physical Review letter
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