The one-neutron knockout from ^{52}Ca in inverse kinematics onto a proton target was performed at â¼230 MeV/nucleon combined with prompt γ spectroscopy. Exclusive quasifree scattering cross sections to bound states in ^{51}Ca and the momentum distributions corresponding to the removal of 1f_{7/2} and 2p_{3/2} neutrons were measured. The cross sections, interpreted within the distorted-wave impulse approximation reaction framework, are consistent with a shell closure at the neutron number N=32, found as strong as at N=28 and N=34 in Ca isotopes from the same observables. The analysis of the momentum distributions leads to a difference of the root-mean-square radii of the neutron 1f_{7/2} and 2p_{3/2} orbitals of 0.61(23) fm, in agreement with the modified-shell-model prediction of 0.7 fm suggesting that the large root-mean-square radius of the 2p_{3/2} orbital in neutron-rich Ca isotopes is responsible for the unexpected linear increase of the charge radius with the neutron number.
Direct proton-knockout reactions of ^{55}Sc at â¼220 MeV/nucleon were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of ^{54}Ca were investigated through γ-ray and invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological internucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors, which describe the wave function overlap of the ^{55}Sc ground state with states in ^{54}Ca. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of ^{55}Sc, valence proton removals populated predominantly the ground state of ^{54}Ca. This counterintuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.
Twenty-one two-proton knockout (p,3p) cross sections were measured from neutron-rich nuclei at â¼250 MeV/nucleon in inverse kinematics. The angular distribution of the three emitted protons was determined for the first time, demonstrating that the (p,3p) kinematics are consistent with two sequential proton-proton collisions within the projectile nucleus. Ratios of (p,3p) over (p,2p) inclusive cross sections follow the trend of other many-nucleon removal reactions, further reinforcing the sequential nature of (p,3p) in neutron-rich nuclei.
Here we present new information on the shape evolution of the very neutron-rich ^{92,94}Se nuclei from an isomer-decay spectroscopy experiment at the Radioactive Isotope Beam Factory at RIKEN. High-resolution germanium detectors were used to identify delayed γ rays emitted following the decay of their isomers. New transitions are reported extending the previously known level schemes. The isomeric levels are interpreted as originating from high-K quasineutron states with an oblate deformation of ßâ¼0.25, with the high-K state in ^{94}Se being metastable and K hindered. Following this, ^{94}Se is the lowest-mass neutron-rich nucleus known to date with such a substantial K hindrance. Furthermore, it is the first observation of an oblate K isomer in a deformed nucleus. This opens up the possibility for a new region of K isomers at low Z and at oblate deformation, involving the same neutron orbitals as the prolate orbitals within the classic Zâ¼72 deformed hafnium region. From an interpretation of the level scheme guided by theoretical calculations, an oblate deformation is also suggested for the ^{94}Se_{60} ground-state band.
Exclusive cross sections and momentum distributions have been measured for quasifree one-neutron knockout reactions from a ^{54}Ca beam striking on a liquid hydrogen target at â¼200 MeV/u. A significantly larger cross section to the p_{3/2} state compared to the f_{5/2} state observed in the excitation of ^{53}Ca provides direct evidence for the nature of the N=34 shell closure. This finding corroborates the arising of a new shell closure in neutron-rich calcium isotopes. The distorted-wave impulse approximation reaction formalism with shell model calculations using the effective GXPF1Bs interaction and ab initio calculations concur our experimental findings. Obtained transverse and parallel momentum distributions demonstrate the sensitivity of quasifree one-neutron knockout in inverse kinematics on a thick liquid hydrogen target with the reaction vertex reconstructed to final state spin-parity assignments.
Nuclear magic numbers correspond to fully occupied energy shells of protons or neutrons inside atomic nuclei. Doubly magic nuclei, with magic numbers for both protons and neutrons, are spherical and extremely rare across the nuclear landscape. Although the sequence of magic numbers is well established for stable nuclei, experimental evidence has revealed modifications for nuclei with a large asymmetry between proton and neutron numbers. Here we provide a spectroscopic study of the doubly magic nucleus 78Ni, which contains fourteen neutrons more than the heaviest stable nickel isotope. We provide direct evidence of its doubly magic nature, which is also predicted by ab initio calculations based on chiral effective-field theory interactions and the quasi-particle random-phase approximation. Our results also indicate the breakdown of the neutron magic number 50 and proton magic number 28 beyond this stronghold, caused by a competing deformed structure. State-of-the-art phenomenological shell-model calculations reproduce this shape coexistence, predicting a rapid transition from spherical to deformed ground states, with 78Ni as the turning point.
Fifty-five inclusive single nucleon-removal cross sections from medium mass neutron-rich nuclei impinging on a hydrogen target at â¼250 MeV/nucleon are measured at the RIKEN Radioactive Isotope Beam Factory. Systematically higher cross sections are found for proton removal from nuclei with an even number of protons as compared to odd-proton number projectiles for a given neutron separation energy. Neutron removal cross sections display no even-odd splitting, contrary to nuclear cascade model predictions. Both effects are understood through simple considerations of neutron separation energies and bound state level densities originating in pairing correlations in the daughter nuclei. These conclusions are supported by comparison with semimicroscopic model predictions, highlighting the enhanced role of low-lying level densities in nucleon-removal cross sections from loosely bound nuclei.
The first γ-ray spectroscopy of ^{52}Ar, with the neutron number N=34, was measured using the ^{53}K(p,2p) one-proton removal reaction at â¼210 MeV/u at the RIBF facility. The 2_{1}^{+} excitation energy is found at 1656(18) keV, the highest among the Ar isotopes with N>20. This result is the first experimental signature of the persistence of the N=34 subshell closure beyond ^{54}Ca, i.e., below the magic proton number Z=20. Shell-model calculations with phenomenological and chiral-effective-field-theory interactions both reproduce the measured 2_{1}^{+} systematics of neutron-rich Ar isotopes, and support a N=34 subshell closure in ^{52}Ar.
This corrects the article DOI: 10.1103/PhysRevLett.119.192501.
In-beam γ-ray spectroscopy of ^{79}Cu is performed at the Radioactive Isotope Beam Factory of RIKEN. The nucleus of interest is produced through proton knockout from a ^{80}Zn beam at 270 MeV/nucleon. The level scheme up to 4.6 MeV is established for the first time and the results are compared to Monte Carlo shell-model calculations. We do not observe significant knockout feeding to the excited states below 2.2 MeV, which indicates that the Z=28 gap at N=50 remains large. The results show that the ^{79}Cu nucleus can be described in terms of a valence proton outside a ^{78}Ni core, implying the magic character of the latter.
We report on the first γ-ray spectroscopy of low-lying states in neutron-rich ^{98,100}Kr isotopes obtained from ^{99,101}Rb(p,2p) reactions at â¼220 MeV/nucleon. A reduction of the 2_{1}^{+} state energies beyond N=60 demonstrates a significant increase of deformation, shifted in neutron number compared to the sharper transition observed in strontium and zirconium isotopes. State-of-the-art beyond-mean-field calculations using the Gogny D1S interaction predict level energies in good agreement with experimental results. The identification of a low-lying (0_{2}^{+}, 2_{2}^{+}) state in ^{98}Kr provides the first experimental evidence of a competing configuration at low energy in neutron-rich krypton isotopes consistent with the oblate-prolate shape coexistence picture suggested by theory.
The first measurement of the low-lying states of the neutron-rich ^{110}Zr and ^{112}Mo was performed via in-beam γ-ray spectroscopy after one proton removal on hydrogen at â¼200 MeV/nucleon. The 2_{1}^{+} excitation energies were found at 185(11) keV in ^{110}Zr, and 235(7) keV in ^{112}Mo, while the R_{42}=E(4_{1}^{+})/E(2_{1}^{+}) ratios are 3.1(2), close to the rigid rotor value, and 2.7(1), respectively. These results are compared to modern energy density functional based configuration mixing models using Gogny and Skyrme effective interactions. We conclude that first levels of ^{110}Zr exhibit a rotational behavior, in agreement with previous observations of lighter zirconium isotopes as well as with the most advanced Monte Carlo shell model predictions. The data, therefore, do not support a harmonic oscillator shell stabilization scenario at Z=40 and N=70. The present data also invalidate predictions for a tetrahedral ground state symmetry in ^{110}Zr.
We report on the measurement of the first 2(+) and 4(+) states of (66)Cr and (70,72)Fe via in-beam γ-ray spectroscopy. The nuclei of interest were produced by (p,2p) reactions at incident energies of 260 MeV/nucleon. The experiment was performed at the Radioactive Isotope Beam Factory, RIKEN, using the DALI 2γ-ray detector array and the novel MINOS device, a thick liquid hydrogen target combined with a vertex tracker. A low-energy plateau of 2(1)(+) and 4(1)(+) energies as a function of the neutron number was observed for N≥38 and N≥40 for even-even Cr and Fe isotopes, respectively. State-of-the-art shell model calculations with a modified Lenzi-Nowacki-Poves-Sieja (LNPS) interaction in the pfg(9/2)d(5/2) valence space reproduce the observations. Interpretation within the shell model shows an extension of the island of inversion at N=40 for more neutron-rich isotopes towards N=50.
The ASACUSA Micromegas Tracker (AMT; ASACUSA: Atomic Spectroscopy and Collisions Using Slow Antiprotons) was designed to be able to reconstruct antiproton-nucleon annihilation vertices in three dimensions. The goal of this device is to study antihydrogen formation processes in the ASACUSA cusp trap, which was designed to synthesise a spin-polarised antihydrogen beam for precise tests of Charge, Parity, and Time (CPT) symmetry invariance. This paper discusses the structure and technical details of an AMT detector built into such an environment, its data acquisition system and the first performance with cosmic rays.
In case of complex anal fistulae, the treatment can include muscular flaps. The gracilis transposition flap is the gold-standard in perineal reconstructive surgery, with wide use during the past decades. However, in some cases, this flap is too short to reach difficult locations such as the posterior perineum. The long head of the biceps femoris, which has already been studied in the electrically stimulated neosphincter formation, could be more appropriate in such clinical situations. Furthermore, its potential advantages, amongst which an excellent functional outcome, would be to allow persistent prone position, during both treatment and reconstruction, as well as a more favorable intramuscular vascularisation. We report the case of a 39-year-old man with a complex recurrent transphincteric posterior anal fistula with an external orifice in the right buttock and complicated with a severe cellulitis, treated with an endo-anal flap combined with a long head of biceps femoris pediculised flap.
Plastic Surgery Procedures/methods , Rectal Fistula/surgery , Surgical Flaps , Adult , Body Mass Index , Cellulitis/complications , Cellulitis/pathology , Cellulitis/surgery , Humans , Male , Rectal Fistula/complications , Rectal Fistula/pathology , Recurrence
Microanastomosis is a microsurgical gesture that involves suturing two very small blood vessels together. This gesture is used in many operations such as avulsed member auto-grafting, pediatric surgery, reconstructive surgery - including breast reconstruction by free flap. When vessels have diameters smaller than one millimeter, hand tremors make movements difficult to control. This paper introduces our preliminary steps towards robotic assistance for helping surgeons to perform microanastomosis in optimal conditions, in order to increase gesture quality and reliability even on smaller diameters. A general needs assessment and an experimental motion analysis were performed to define the requirements of the robot. Geometric parameters of the kinematic structure were then optimized to fulfill specific objectives. A prototype of the robot is currently being designed and built in order to providing a sufficient increase in accuracy without prolonging the duration of the procedure.
Anastomosis, Surgical/methods , Microsurgery/instrumentation , Plastic Surgery Procedures/instrumentation , Robotic Surgical Procedures/instrumentation , Anastomosis, Surgical/instrumentation , Animals , Arteries/surgery , Equipment Design , Microsurgery/methods , Motion , Rats , Plastic Surgery Procedures/methods , Reproducibility of Results , Robotic Surgical Procedures/methods
Pelvic magnetic resonance imaging (MRI) has been used successfully to diagnose ovarian masses that cannot be adequately evaluated using pelvic ultrasound. T1 hyperintensity is a common finding in an ovarian mass and has important diagnostic implications. The aims of this review are to list the substances that may produce high signal intensity on T1-weighted MRI, to explain the physical basis for causes of the high T1 signal intensity, and to describe common and uncommon T1 hyperintense ovarian lesions. The morphological findings, the imaging features of the additional sequences, and clinical variables can help in the differential diagnosis, and in some cases, enable a specific diagnosis, leading to appropriate management of the patient.
Magnetic Resonance Imaging/methods , Ovarian Neoplasms/diagnosis , Ovary/pathology , Diagnosis, Differential , Female , Humans , Ovarian Diseases/diagnosis
PURPOSE: Our goal was to determine how interpreting diagnostic CT together with PET-CT could improve the assessment of morphology in onco-haematology. PATIENTS AND METHODS: Fifty-nine patients with aggressive lymphoma were retrospectively included. The diagnostic CT scan was interpreted by two radiologists, followed by a combined analysis of the CT and the PET-CT carried out by two specialists in metabolic and morphological imaging. The diagnostic performances were assessed in terms of sensitivity and specificity, then concordance and discordance rates (kappa) were studied. RESULTS: A combined interpretation of CT and PET-CT showed better diagnostic performances than those of interpretations of CT only in the assessment of nodal sites (826 sites, sensitivity of 99% versus 85%, P<0.05), extranodal sites (649 sites, sensitivity of 88% versus 78%) and bone sites (one analysed per patient, sensitivity of 50% versus 27%). The combined interpretation also improved inter-observer agreement and led to an upgraded Ann Arbor staging in 15% of patients, with a change of treatment in 10%. CONCLUSION: Interpretation of diagnostic CT in onco-haematology can be improved by combining it with an assessment of PET-CT. The synergy between metabolic and morphological information leads to improved diagnostic capabilities and renders interpretations more reproducible.
Energy Metabolism/physiology , Hodgkin Disease/diagnosis , Image Enhancement/methods , Image Interpretation, Computer-Assisted , Lymphoma, Follicular/diagnosis , Lymphoma, Large B-Cell, Diffuse/diagnosis , Positron-Emission Tomography/methods , Tomography, X-Ray Computed/methods , Adolescent , Adult , Aged , Bone Marrow/pathology , Cooperative Behavior , Female , Hodgkin Disease/physiopathology , Humans , Interdisciplinary Communication , Iohexol/analogs & derivatives , Lymph Nodes/pathology , Lymphoma, Follicular/physiopathology , Lymphoma, Large B-Cell, Diffuse/physiopathology , Male , Middle Aged , Neoplasm Invasiveness , Neoplasm Staging , Observer Variation , Retrospective Studies , Sensitivity and Specificity , Spleen/pathology , Young Adult
The majority of breast lesions in men are benign. Gynaecomastia is a very common condition in which hormonal changes cause male breasts to enlarge. Three radiological patterns of gynaecomastia have been described: nodular, dendritic, and diffuse glandular pattern. The main differential diagnosis is lipomastia, which is when adipose tissue deposits are found in the subcutaneous tissue. Male breast cancer is rare. The main risk factors are pathologies that cause hormonal imbalances, a history of chest irradiation, and a family history of breast cancer (particularly in families carrying a mutation of the gene BRCA2). Mammography usually shows a mass with no calcifications. Sonography is useful to investigate local disease spread, and for detecting any enlarged axillary lymph nodes. MRI is not currently indicated to investigate male breast cancer. Very often, the clinical examination alone is enough to distinguish benign lesions from malignant lesions. Imaging must not be automatically carried out, but rather it should be used when the diagnosis is clinically uncertain or when patients present risk factors for breast cancer, as well as for guiding biopsies and for assessing disease spread.
Breast Diseases/diagnostic imaging , Breast Neoplasms, Male/diagnostic imaging , Diagnosis, Differential , Gynecomastia/diagnostic imaging , Humans , Male , Radiography , Ultrasonography
Preiser's disease, or avascular necrosis of the scaphoid occurs without fracture or non-union. Between 1998 and 2009, the authors report on 5 patients who complained of mild pain on the radial aspect of the wrist, associated with stiffness and/or loss of strength. Our management consisted in different options: one bilateral intraarticular injection of hyaluronic acid, three vascularised radial bone graft and one resection of the first carpal row. With four and a half years follow-up, our results are quite satisfactory for improvement of pain, sometimes with residual postoperative stiffness. Management remains difficult because Preiser's disease is rare and there are no relevant prospective control studies. We attempt to provide an algorithm for early management of the disease and to answer the question: "until when can we save the scaphoid and how?"
Osteonecrosis , Scaphoid Bone , Adult , Female , Humans , Male , Middle Aged , Osteonecrosis/therapy
