Sensitivity Kernels for Flows in Time-Distance Helioseismology: Extension to Spherical Geometry

We extend an existing Born approximation method for calculating the linear sensitivity of helioseismic travel times to flows from Cartesian to spherical geometry. This development is necessary for using the Born approximation for inferring large-scale flows in the deep solar interior. In a first sanity check, we compare two $f-$mode kernels from our spherical method and from an existing Cartesian method. The horizontal and total integrals agree to within 0.3 %. As a second consistency test, we consider a uniformly rotating Sun and a travel distance of 42 degrees. The analytical travel-time difference agrees with the forward-modelled travel-time difference to within 2 %. In addition, we evaluate the impact of different choices of filter functions on the kernels for a meridional travel distance of 42 degrees. For all filters, the sensitivity is found to be distributed over a large fraction of the convection zone. We show that the kernels depend on the filter function employed in the data analysis process. If modes of higher harmonic degree ($90\lesssim l \lesssim 170$) are permitted, a noisy pattern of a spatial scale corresponding to $l\approx 260$ appears near the surface. When mainly low-degree modes are used ($l\lesssim70$), the sensitivity is concentrated in the deepest regions and it visually resembles a ray-path-like structure. Among the different low-degree filters used, we find the kernel for phase-speed filtered measurements to be best localized in depth.Comment: 17 pages, 5 figures, 2 tables, accepted for publication in ApJ. v2: typo in arXiv author list correcte

Unraveling North-African riverine and eolian contributions to central Mediterranean sediments during Holocene sapropel S1 formation

Hydroclimate variability has exerted a fundamental control on the alternating deposition of organic-lean marl and organic-rich sapropel sediments in the eastern Mediterranean Sea (EMS). However, the exact mechanisms regarding the freshwater sources and related changes are still debated. Here, Sr and Nd isotopes and high-resolution elemental data are used to constrain different riverine and eolian supplies to the central Mediterranean over the past 9.8 ka. The detrital sediments in core CP10BC, taken at the margin of the Libyan shelf in the southwestern Ionian Sea, can be described by a three-endmember mixing system based on Sr and Nd isotopic compositions. The same systematics can also be deduced from Ti and K compositional variability. The endmembers comprise: Saharan Dust, Aegean/Nile, and Libyan Soil, representing the eolian supply from North Africa, the riverine inputs from the Aegean/Nile areas, as well as the riverine and shelf-derived fluxes from the Libyan-Tunisian margin, respectively. For the sapropel S1 period in particular, we find important detrital supplies from fossil river/wadi systems along the Libyan-Tunisian margin, activated by intensified African monsoon precipitation. Combining the temporal profiles with the consistent variability observed in the 87Sr/86Sr–1000/Sr diagram, such Libyan contribution has been most prominent during the uppermost period of sapropel S1 in core CP10BC. This observation is in agreement with hydroclimate reconstructions of northwestern Libya. Comparison of the Sr-Nd isotope data between core CP10BC and four cores taken along a west–east transect throughout the EMS shows that this detrital supply originated mainly from western Libya/Tunisia, and was transported as far eastward as ∼25°E while being diluted by an increasing Nile contribution

Alpha-decay properties of superheavy elements Z=113−125Z=113-125 in the relativistic mean-field theory with vector self-coupling of ω\omega meson

We have investigated properties of $\alpha$-decay chains of recently produced superheavy elements Z=115 and Z=113 using the new Lagrangian model NL-SV1 with inclusion of the vector self-coupling of $\omega$ meson in the framework of the relativistic mean-field theory. It is shown that the experimentally observed alpha-decay energies and half-lives are reproduced well by this Lagrangian model. Further calculations for the heavier elements with Z=117-125 show that these nuclei are superdeformed with a prolate shape in the ground state. A superdeformed shell-closure at Z=118 lends an additional binding and an extra stability to nuclei in this region. Consequently, it is predicted that the corresponding $Q_\alpha$ values provide $\alpha$-decay half-lives for heavier superheavy nuclei within the experimentally feasible conditions. The results are compared with those of macroscopic-microscopic approaches. A perspective of the difference in shell effects amongst various approaches is presented and its consequences on superheavy nuclei are discussed.Comment: Revised version, 14 pages, 12 eps figures. To appear in PRC. Discussion on shell effects is shortened in the revised version. However, commonality of the role of shell effects in extreme superheavy regions and in the regions near the r-process path is maintained. Existence of a secondary superdeformed minimum for Z=113 is verified with another Lagrangian se

Model simulations on the long-term dispersal of 137Cs released into the Pacific Ocean off Fukushima

A sequence of global ocean circulation models, with horizontal mesh sizes of 0.5°, 0.25° and 0.1°, are used to estimate the long-term dispersion by ocean currents and mesoscale eddies of a slowly decaying tracer (half-life of 30 years, comparable to that of 137Cs) from the local waters off the Fukushima Dai-ichi Nuclear Power Plants. The tracer was continuously injected into the coastal waters over some weeks; its subsequent spreading and dilution in the Pacific Ocean was then simulated for 10 years. The simulations do not include any data assimilation, and thus, do not account for the actual state of the local ocean currents during the release of highly contaminated water from the damaged plants in March–April 2011. An ensemble differing in initial current distributions illustrates their importance for the tracer patterns evolving during the first months, but suggests a minor relevance for the large-scale tracer distributions after 2–3 years. By then the tracer cloud has penetrated to depths of more than 400 m, spanning the western and central North Pacific between 25°N and 55°N, leading to a rapid dilution of concentrations. The rate of dilution declines in the following years, while the main tracer patch propagates eastward across the Pacific Ocean, reaching the coastal waters of North America after about 5–6 years. Tentatively assuming a value of 10 PBq for the net 137Cs input during the first weeks after the Fukushima incident, the simulation suggests a rapid dilution of peak radioactivity values to about 10 Bq m−3 during the first two years, followed by a gradual decline to 1–2 Bq m−3 over the next 4–7 years. The total peak radioactivity levels would then still be about twice the pre-Fukushima values

The Randomized Shortened Dental Arch Study: Tooth Loss

The evidence concerning the management of shortened dental arch (SDA) cases is sparse. This multi-center study was aimed at generating data on outcomes and survival rates for two common treatments, removable dental prostheses (RDP) for molar replacement or no replacement (SDA). The hypothesis was that the treatments lead to different incidences of tooth loss. We included 215 patients with complete molar loss in one jaw. Molars were either replaced by RDP or not replaced, according to the SDA concept. First tooth loss after treatment was the primary outcome measure. This event occurred in 13 patients in the RDP group and nine patients in the SDA group. The respective Kaplan-Meier survival rates at 38 months were 0.83 (95% CI: 0.74-0.91) in the RDP group and 0.86 (95% CI: 0.78-0.95) in the SDA group, the difference being non-significant

Image-based dosimetry for 225Ac-PSMA-I&T therapy using quantitative SPECT

Purpose!#!After a decade of PET/MR, the case of attenuation correction (AC) remains open. The initial four-compartment (air, water, fat, soft tissue) Dixon-based AC scheme has since been expanded with several features, the latest being MR field-of-view extension and a bone atlas. As this potentially changes quantification, we evaluated the impact of these features in PET AC in prostate cancer patients.!##!Methods!#!Two hundred prostate cancer patients were examined with either !##!Results!#!High correlation and no visually perceivable differences between all evaluated methods (r > 0.996) were found. The mean relative difference in lesion uptake of !##!Conclusions!#!Based on these results and the encountered bone atlas registration inaccuracy, we deduce that including bones and extending the MR field-of-view did not introduce clinically significant differences in PSMA diagnostic accuracy and tracer uptake quantification in prostate cancer pelvic lesions, facilitating the analysis of serial studies respectively. However, in the absence of ground truth data, we advise against atlas-based methods when comparing serial scans for bone lesions

Shell structure of superheavy nuclei in self-consistent mean-field models

We study the extrapolation of nuclear shell structure to the region of superheavy nuclei in self-consistent mean-field models -- the Skyrme-Hartree-Fock approach and the relativistic mean-field model -- using a large number of parameterizations. Results obtained with the Folded-Yukawa potential are shown for comparison. We focus on differences in the isospin dependence of the spin-orbit interaction and the effective mass between the models and their influence on single-particle spectra. While all relativistic models give a reasonable description of spin-orbit splittings, all non-relativistic models show a wrong trend with mass number. The spin-orbit splitting of heavy nuclei might be overestimated by 40%-80%. Spherical doubly-magic superheavy nuclei are found at (Z=114,N=184), (Z=120,N=172) or (Z=126,N=184) depending on the parameterization. The Z=114 proton shell closure, which is related to a large spin-orbit splitting of proton 2f states, is predicted only by forces which by far overestimate the proton spin-orbit splitting in Pb208. The Z=120 and N=172 shell closures predicted by the relativistic models and some Skyrme interactions are found to be related to a central depression of the nuclear density distribution. This effect cannot appear in macroscopic-microscopic models which have a limited freedom for the density distribution only. In summary, our findings give a strong argument for (Z=120,N=172) to be the next spherical doubly-magic superheavy nucleus.Comment: 22 pages REVTeX, 16 eps figures, accepted for publication in Phys. Rev.