Abstract
Nuclear charge radii globally scale with atomic mass number
A
as
A
1∕3
, and isotopes with an odd number of neutrons are usually slightly smaller in size than their even-neutron neighbours. ...This odd–even staggering, ubiquitous throughout the nuclear landscape
1
, varies with the number of protons and neutrons, and poses a substantial challenge for nuclear theory
2–4
. Here, we report measurements of the charge radii of short-lived copper isotopes up to the very exotic
78
Cu (with proton number
Z
= 29 and neutron number
N
= 49), produced at only 20 ions s
–1
, using the collinear resonance ionization spectroscopy method at the Isotope Mass Separator On-Line Device facility (ISOLDE) at CERN. We observe an unexpected reduction in the odd–even staggering for isotopes approaching the
N
= 50 shell gap. To describe the data, we applied models based on nuclear density functional theory
5,6
and
A
-body valence-space in-medium similarity renormalization group theory
7,8
. Through these comparisons, we demonstrate a relation between the global behaviour of charge radii and the saturation density of nuclear matter, and show that the local charge radii variations, which reflect the many-body polarization effects, naturally emerge from
A
-body calculations fitted to properties of
A
≤ 4 nuclei.
We investigate the effects of two-body currents on magnetic dipole moments of medium-mass and heavy nuclei using the valence-space in-medium similarity renormalization group with chiral effective ...field theory interactions and currents. Focusing on near doubly magic nuclei from oxygen to bismuth, we have found that the leading two-body currents globally improve the agreement with experimental magnetic moments. Moreover, our results show the importance of multishell effects for Ca 41 , which suggest that the Z = N = 20 gap in Ca 40 is not as robust as in Ca 48 . The increasing contribution of two-body currents in heavier systems is explained by the operator structure of the center-of-mass dependent Sachs term. Published by the American Physical Society 2024
Since the 26 December 2004 Indian Ocean tsunami, the role of mangrove forests as natural defenses protecting coastal communities from tsunami disaster has been highlighted. However, some mangrove ...forests were destroyed by that tsunami. They are expected to have lost their protective functions. In this study, we develop a fragility function to assess the mangrove trees' vulnerability, expressed as the damage probability of mangrove trees, based on field surveys and numerical modeling of the 2004 Indian Ocean tsunami in Banda Aceh, Indonesia. Based on the fragility function, we reconstruct a numerical model of tsunami inundation including the performance of mangrove forests in terms of reducing tsunami damage. The model reveals that a 10 year old mangrove forest in a 500 m wide area can reduce a tsunami's hydrodynamic force by approximately 70% for an incident wave of 3.0 m inundation depth and a wave period of 40 min at the shoreline. The model also shows, for a tsunami inundation depth of greater than 4 m, that a 10 year old mangrove forest would be mostly destroyed and that it would lose its force reduction capacity. Moreover, approximately 80% of a 30 year old mangrove forest would survive a 5 m tsunami and absorb 50% of the tsunami's hydrodynamic force.
Abstract
The tin isotope
100
Sn is of singular interest for nuclear structure due to its closed-shell proton and neutron configurations. It is also the heaviest nucleus comprising protons and ...neutrons in equal numbers—a feature that enhances the contribution of the short-range proton–neutron pairing interaction and strongly influences its decay via the weak interaction. Decay studies in the region of
100
Sn have attempted to prove its doubly magic character
1
but few have studied it from an ab initio theoretical perspective
2,3
, and none of these has addressed the odd-proton neighbours, which are inherently more difficult to describe but crucial for a complete test of nuclear forces. Here we present direct mass measurements of the exotic odd-proton nuclide
100
In, the beta-decay daughter of
100
Sn, and of
99
In, with one proton less than
100
Sn. We use advanced mass spectrometry techniques to measure
99
In, which is produced at a rate of only a few ions per second, and to resolve the ground and isomeric states in
101
In. The experimental results are compared with ab initio many-body calculations. The 100-fold improvement in precision of the
100
In mass value highlights a discrepancy in the atomic-mass values of
100
Sn deduced from recent beta-decay results
4,5
.
We previously found an inverse relationship between sialidase Neu1 expression and metastatic potential of marine cancer cells. To elucidate the mechanism underlying the cellular events, the human ...sialidase gene NEV1 was overexpressed or silenced in colon cancer HT-29 cells. When NEU1-overexpressing cells were injected transsplenically into mice, in vivo liver metastasis was significantly reduced. NEU1 suppressed cell migration, invasion and adhesion in vitro, whereas the silencing resulted in the opposite. One of the major molecular changes by NEU1 was decreased sialylation of integrin β4, assessed by PNA-and MAL-II-lectin blotting of immunoprecipitates with anti-integrin β4 antibody. The desialylation was accompanied by decreased phosphorylation of the integrin followed by attenuation of focal adhesion kinase and Erk1/2 pathway. Moreover, NEU1 caused downregulation of matrix metalloproteinase-7, overexpression of which is associated with cancer metastasis. Treatment of the cells with Ga1NAc-α-O-benzyl, an inhibitor of O-glycosylation, showed increased PNA-positive integrin β4 with its decreased phosphorylation, indicating that sialic acid removal from the integrin O-glycans results in the decreased phosphorylation. Biotinylation and immunofluorescence staining exhibited some NEU1 molecules to be at the cell surface accessible to the integrin. These results suggest that NEU1 is important in regulation of integrin β4-mediated signaling, leading to suppression of metastasis. doi:10.1038/onc.2008.471; published online 19 January 2009 Keywords: sialidase; integrin (34; sialic acid; metastasis; invasion; MMP-7
We present converged ab initio calculations of structure factors for elastic spin-dependent WIMP scattering off all nuclei used in dark matter direct-detection searches: ^{19}F, ^{23}Na, ^{27}Al, ...^{29}Si, ^{73}Ge, ^{127}I, and ^{129,131}Xe. From a set of established two- and three-nucleon interactions derived within chiral effective field theory, we construct consistent WIMP-nucleon currents at the one-body level, including effects from axial-vector two-body currents. We then apply the in-medium similarity renormalization group to construct effective valence-space Hamiltonians and consistently transformed operators of nuclear responses. Combining the recent advances of natural orbitals with three-nucleon forces expressed in large spaces, we obtain basis-space converged structure factors even in heavy nuclei. Generally results are consistent with previous calculations but large uncertainties in ^{127}I highlight the need for further study.
Mass measurements continue to provide invaluable information for elucidating nuclear structure and scenarios of astrophysical interest. The transition region between the Z=20 and 28 proton shell ...closures is particularly interesting due to the onset and evolution of nuclear deformation as nuclei become more neutron-rich. This provides a critical testing ground for emerging ab-initio nuclear structure models. Here, we present high-precision mass measurements of neutron-rich chromium isotopes using the sensitive electrostatic Multiple-Reflection Time-Of-Flight Mass Spectrometer (MR-TOF-MS) at TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN) facility. Our high-precision mass measurements of 59,61−63Cr confirm previous results, and the improved precision in measurements of 64−65Cr refine the mass surface beyond N=40. With the ab initio in-medium similarity renormalization group, we examine the trends in collectivity in chromium isotopes and give a complete picture of the N=40 island of inversion from calcium to nickel.
In spite of the high-density and strongly correlated nature of the atomic nucleus, experimental and theoretical evidence suggests that around particular 'magic' numbers of nucleons, nuclear ...properties are governed by a single unpaired nucleon1,2. A microscopic understanding of the extent of this behaviour and its evolution in neutron-rich nuclei remains an open question in nuclear physics3-5. The indium isotopes are considered a textbook example of this phenomenon6, in which the constancy of their electromagnetic properties indicated that a single unpaired proton hole can provide the identity of a complex many-nucleon system6,7. Here we present precision laser spectroscopy measurements performed to investigate the validity of this simple single-particle picture. Observation of an abrupt change in the dipole moment at N=82 indicates that, whereas the single-particle picture indeed dominates at neutron magic number N= 82 (refs.2,8), it does not for previously studied isotopes. To investigate the microscopic origin ofthese observations, our work provides a combined effort with developments in two complementary nuclear many-body methods: ab initio valence-space in-medium similarity renormalization group and density functional theory (DFT). We find that the inclusion of time-symmetry-breaking mean fields is essential for a correct description of nuclear magnetic properties, which were previously poorly constrained. These experimental and theoretical findings are key to understanding how seemingly simple single-particle phenomena naturally emerge from complex interactions among protons and neutrons.
Summary
Background
Taxanes are the current first‐line treatment for advanced cutaneous angiosarcoma (CAS) for patients who are considered difficult to treat with doxorubicin owing to advanced age or ...comorbidity. However, no effective second‐line therapy for such patients has been established.
Methods
We designed a single‐arm prospective observational study of eribulin mesylate (ERB) administered at a dose of 1·4 mg m−2 on days 1 and 8 in a 21‐day cycle. Patients with advanced CAS who were previously treated with a taxane and were scheduled to begin ERB treatment were enrolled. The primary endpoint was overall survival (OS) and the secondary endpoints were response rate (RR), progression‐free survival (PFS) and toxicity assessment.
Results
We enrolled a total of 25 patients. The median OS and PFS were 8·6 months and 3·0 months, respectively. The best overall RR was 20% (five of 25). In total, 16 grade 3/4 severe adverse events (SAEs) occurred; however, all patients recovered. Patients who achieved partial response or stable disease as best response had longer OS than those with progressive disease (median OS not reached and 3·3 months, respectively; P < 0·001). Patients who did not experience SAEs showed longer OS than those who did (median OS 18·8 months and 7·5 months, respectively; P < 0·05). Patients with distant metastasis had shorter median OS than those with locoregional disease, but without statistically significant difference.
Conclusions
ERB showed a promising RR and is a potential candidate for second‐line treatment for patients with CAS, after treatment with taxanes. However, owing to the occurrence of SAEs in over half of the participants, caution should be exercised regarding ERB use in elderly patients.
What is already known about this topic?
Taxanes are the current first‐line treatment for patients with advanced cutaneous angiosarcoma (CAS) who are considered difficult to treat with doxorubicin owing to advanced age or comorbidity.
No effective therapy for taxane‐resistant CAS has been established thus far.
Eribulin suppresses microtubule polymerization and elicits an antitumour effect similar to that of taxanes.
What does this study add?
In our single‐arm prospective observational study to evaluate the efficacy of eribulin for treating patients with advanced CAS who previously received taxanes, the median overall survival and progression‐free survival were 8·6 and 3·0 months, respectively.
Response rates at weeks 7, 13 and 25 were 20%, 17% and 14%, respectively.
Although 16 grade 3/4 severe adverse events occurred, all patients recovered.
Eribulin showed a promising response rate and is a potential candidate for second‐line treatment in CAS after taxane treatment.
Linked Comment: Smrke and Benson. Br J Dermatol 2020; 183:797–798.
What is already known about this topic?
Taxanes are the current first‐line treatment for patients with advanced cutaneous angiosarcoma (CAS) who are considered difficult to treat with doxorubicin owing to advanced age or comorbidity.
No effective therapy for taxane‐resistant CAS has been established thus far.
Eribulin suppresses microtubule polymerization and elicits an antitumour effect similar to that of taxanes.
What does this study add?
In our single‐arm prospective observational study to evaluate the efficacy of eribulin for treating patients with advanced CAS who previously received taxanes, the median overall survival and progression‐free survival were 8·6 and 3·0 months, respectively.
Response rates at weeks 7, 13 and 25 were 20%, 17% and 14%, respectively.
Although 16 grade 3/4 severe adverse events occurred, all patients recovered.
Eribulin showed a promising response rate and is a potential candidate for second‐line treatment in CAS after taxane treatment.
Linked Comment: Smrke and Benson. Br J Dermatol 2020; 183:797–798.
We report high-precision mass measurements of ^{50-55}Sc isotopes performed at the LEBIT facility at NSCL and at the TITAN facility at TRIUMF. Our results provide a substantial reduction of their ...uncertainties and indicate significant deviations, up to 0.7 MeV, from the previously recommended mass values for ^{53-55}Sc. The results of this work provide an important update to the description of emerging closed-shell phenomena at neutron numbers N=32 and N=34 above proton-magic Z=20. In particular, they finally enable a complete and precise characterization of the trends in ground state binding energies along the N=32 isotone, confirming that the empirical neutron shell gap energies peak at the doubly magic ^{52}Ca. Moreover, our data, combined with other recent measurements, do not support the existence of a closed neutron shell in ^{55}Sc at N=34. The results were compared to predictions from both ab initio and phenomenological nuclear theories, which all had success describing N=32 neutron shell gap energies but were highly disparate in the description of the N=34 isotone.
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