A search for the heaviest isotopes of fluorine, neon, and sodium was conducted by fragmentation of an intense ^{48}Ca beam at 345 MeV/nucleon with a 20-mm-thick beryllium target and identification ...of isotopes in the large-acceptance separator BigRIPS at the RIKEN Radioactive Isotope Beam Factory. No events were observed for ^{32,33}F, ^{35,36}Ne, and ^{38}Na and only one event for ^{39}Na after extensive running. Comparison with predicted yields excludes the existence of bound states of these unobserved isotopes with high confidence levels. The present work indicates that ^{31}F and ^{34}Ne are the heaviest bound isotopes of fluorine and neon, respectively. The neutron dripline has thus been experimentally confirmed up to neon for the first time since ^{24}O was confirmed to be the dripline nucleus nearly 20 years ago. These data provide new keys to understanding the nuclear stability at extremely neutron-rich conditions.
Crocodylia is the sole extant remnant of quadrupedal archosaurs playing a pivotal role in understanding the evolution of growth allometry in the archosaur locomotor apparatus. However, among ...crocodylians, the postnatal growth of the postcranial skeleton has almost exclusively been examined in Alligator mississippiensis, and whether other species share the same growth pattern is unknown. Here, we tested whether the following allometric trends are conserved across Crocodylia: (1) forelimb length grows isometrically relative to hindlimb length; (2) fore‐ and hindlimb lengths become relatively shorter with increasing body size; and (3) long bone cross‐sectional geometry becomes more robust relative to body size. We examined the relationships of limb lengths, stylopodial circumferences and presacral length (body size proxy) in extant crocodylians using reduced major axis regressions and compared the slopes among species. The result revealed non‐uniform growth patterns of limb architecture among living crocodylians. Generally, the hindlimb grows with negative allometry against the forelimb in non‐gavialid crocodylians, whereas two gavialids (Gavialis gangeticus and Tomistoma schlegelii) showed isometry in hind‐ vs. forelimb length scaling, potentially reflecting their unique locomotor ecology. Femur circumference scales negatively against humerus circumference in most of the species examined, which may be related to the anterior shift of the center of mass during growth. Stylopodial circumferences scale variously against stylopodial lengths and presacral length in crocodylians, lending little support to hypotheses that these allometries correlate with adult body size or metabolism (i.e. ectothermic or endothermic) in tetrapods.
Crocodylia is the sole remnant of quadrupedal archosaurs playing a significant role in understanding the evolution of archosaur locomotor ontogeny. However, the postcranial growth has almost exclusively been examined in Alligator mississippiensis, and whether other species share the same growth pattern is unknown. In this paper, we provide the first comprehensive interspecific comparisons of the limb and body proportion ontogeny among extant crocodylian species. The result showed that the fore‐ vs. hindlimb length scaling patterns are different between non‐gavialids and gavialids (Gavialis gangeticus and Tomistoma schlegelii), probably reflecting the unique locomotor ecology in gavialids. The growth of humeral midshaft circumference is faster than that of femur in most of the species, suggesting that the ontogenetic anterior shift of the center of mass might be the shared characteristic in Crocodylia.
•In-flight particle identification of RI beams developed for BigRIPS separator.•Atomic number Z and mass-to-charge ratio A/Q are deduced by the TOF-Bρ-ΔE.•Precise determinations of Bρ and TOF with ...trajectory reconstruction and slew correction, respectively.•The achieved A/Q resolution is high enough to clearly identify the charge state.•Thorough removal of background events improves the reliability of identification.
We have developed a method for achieving excellent resolving power in in-flight particle identification of radioactive isotope (RI) beams at the BigRIPS fragment separator at the RIKEN Nishina Center RI Beam Factory (RIBF). In the BigRIPS separator, RI beams are identified by their atomic number Z and mass-to-charge ratio A/Q which are deduced from the measurements of time of flight (TOF), magnetic rigidity (Bρ) and energy loss (ΔE), and delivered as tagged RI beams to a variety of experiments including secondary reaction measurements. High A/Q resolution is an essential requirement for this scheme, because the charge state Q of RI beams has to be identified at RIBF energies such as 200–300MeV/nucleon. By precisely determining the Bρ and TOF values, we have achieved relative A/Q resolution as good as 0.034% (root-mean-square value). The achieved A/Q resolution is high enough to clearly identify the charge state Q in the Z versus A/Q particle identification plot, where fully-stripped and hydrogen-like peaks are very closely located. The precise Bρ determination is achieved by refined particle trajectory reconstruction, while a slew correction is performed to precisely determine the TOF value. Furthermore background events are thoroughly removed to improve reliability of the particle identification. In the present paper we present the details of the particle identification scheme in the BigRIPS separator. The isotope separation in the BigRIPS separator is also briefly introduced.
A crucial requirement for quantum-information processing is the realization of multiple-qubit quantum gates. Here, we demonstrate an electron spin-based all-electrical two-qubit gate consisting of ...single-spin rotations and interdot spin exchange in a double quantum dot. A partially entangled output state is obtained by the application of the two-qubit gate to an initial, uncorrelated state. We find that the degree of entanglement is controllable by the exchange operation time. The approach represents a key step towards the realization of universal multiple-qubit gates.
Exposure to workplace aggression adversely affects workers' health; however, little is known regarding the impact of specific types of verbal content.
We aimed to examine the relationship between ...exposure to several types of aggressive words at work and the victim's depressive symptoms and sleep disturbance using text mining.
We conducted a longitudinal survey with 800 workers in wholesale and retail companies; of which, 500 responded to the follow-up survey. The Centre for Epidemiologic Studies-Depression Scale and Pittsburgh Sleep Quality Index were filled out by the participants, and their responses were analysed by logistic regression to evaluate the risk of depression or sleep problems. We collected exact aggressive words encountered at work over the past year as a dependent variable and classified it into four types using text mining, such as words criticizing one's performance.
The follow-up rate was 63%. Exposure to words threatening one's life showed a significant relationship with the risk of depression (odds ratio OR = 13.94, 95% confidence interval CI = 1.76-110.56). The exposure to words criticizing one's job performance is significantly related to the risk of sleep disturbance (OR = 5.56, 95% CI = 2.08-14.88).
These findings suggest that different contents of verbal aggression can have different impacts on workers' health. This indicates that not only overtly threatening and abusive language but also words related to one's performance can be a risk factor for workers, depending on how they are delivered. To mitigate the adverse effects, promoting effective communication and cultivating psychological detachment from work may be beneficial.
The field limit of a superconducting radio-frequency cavity made of a type II superconductor with a large Ginzburg–Landau parameter is studied, taking the effects of nano-scale surface topography ...into account. If the surface is ideally flat, the field limit is imposed by the superheating field. On the surface of cavity, however, nano-defects almost continuously distribute and suppress the superheating field everywhere. The field limit is imposed by an effective superheating field given by the product of the superheating field for an ideal flat surface and a suppression factor that contains the effects of nano-defects. A nano-defect is modeled by a triangular groove with a depth smaller than the penetration depth. An analytical formula for the suppression factor of bulk and multilayer superconductors is derived in the framework of the London theory. As an immediate application, the suppression factor of the dirty Nb processed by electropolishing is evaluated by using results of surface topographic study. The estimated field limit is consistent with the present record field of nitrogen-doped Nb cavities. Suppression factors of surfaces of other bulk and multilayer superconductors, and those after various surface processing technologies, can also be evaluated by using the formula.
SAMURAI spectrometer for RI beam experiments Kobayashi, T.; Chiga, N.; Isobe, T. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
12/2013, Letnik:
317
Journal Article
Recenzirano
A large-acceptance multiparticle spectrometer SAMURAI has been constructed at the RIKEN RI Beam Factory (RIBF) for RI beam experiments. It was designed primarily for kinematically complete ...experiments such as the invariant-mass spectroscopy of particle-unbound states in exotic nuclei, by detecting heavy fragments and projectile-rapidity nucleons in coincidence. The system consists of a superconducting dipole magnet, beam line detectors, heavy fragment detectors, neutron detectors, and proton detectors. The SAMURAI spectrometer was commissioned in March 2012, and a rigidity resolution of about 1/1500 was obtained for RI beams up to 2.4GeV/c.
A study of metal‐organic chemical vapor deposition (MOCVD) grown AlN nucleation layer (NL) on breakdown characteristics for GaN‐on‐Si is presented. It is widely believed that AlN NL can act as an ...insulator because of its large band gap ∼6.2 eV. On contrary, this study of AlN NL/Si reveals conductive nature and shows high vertical leakage. The structural examinations along with electrical characterization show AlN NL/Si quality depends on the growth temperature. The surface morphology and presence of unintentional oxygen impurities govern the vertical leakage of AlN NL/Si. Interestingly, the AlN NL influences the growth of subsequent epitaxial layers as well as their vertical breakdown voltages (BVs). Further, it is found that AlGaN intermediate layer and multipairs of AlGaN/AlN strained layer superlattice (SLS) grown over AlN NL with better surface properties enhances the vertical BV. A high BV of 1.3 kV is achieved for SLS multipairs with a total thickness of 4.4 μm and the translated breakdown field strength is 2.8 MV cm−1 for MOCVD grown GaN‐on‐Si.
The rapid rise of spintronics and quantum information science has led to a strong interest in developing the ability to coherently manipulate electron spins. Electron spin resonance is a powerful ...technique for manipulating spins that is commonly achieved by applying an oscillating magnetic field. However, the technique has proven very challenging when addressing individual spins. In contrast, by mixing the spin and charge degrees of freedom in a controlled way through engineered non-uniform magnetic fields, electron spin can be manipulated electrically without the need of high-frequency magnetic fields. Here we report experiments in which electrically driven addressable spin rotations on two individual electrons were realized by integrating a micrometre-size ferromagnet into a double-quantum-dot device. We find that it is the stray magnetic field of the micromagnet that enables the electrical control and spin selectivity. The results suggest that our approach can be tailored to multidot architecture and therefore could open an avenue towards manipulating electron spins electrically in a scalable way.
Prior studies have presented contradictory results after analyzing associations between donor and recipient sex on survival after heart transplantation and causes of death such as acute rejection ...(AR) and cardiac allograft vasculopathy (CAV). We used the International Society for Heart and Lung Transplantation (ISHLT) Registry, the largest repository of heart transplant outcomes worldwide, to comprehensively address these questions.
We studied 60,584 adult recipients of heart transplants performed between 1990 and 2008. Outcomes of interest were overall survival, death-censored allograft survival, AR, and CAV, which were studied using regression models. To assess whether donor/recipient sex mismatch affected outcomes, the experience of male recipients with female vs male donors was compared with that of female recipients with female vs male donors through inclusion of an interaction term between donor and recipient sex.
Significant differences were observed between male and female recipients in overall survival and death-censored allograft survival for female vs male donors. Male recipients of female allografts had a 10% increase in adjusted mortality relative to male recipients of male allografts, whereas female recipients of female allografts had a 10% decrease in adjusted mortality relative to female recipients of male allografts (p < 0.0001). Findings were similar for death-censored allograft survival. Differences in the effect of donor sex on AR or CAV between male and female recipients were not significant.
Analysis of the ISHLT data set has demonstrated a strong association between donor/recipient sex mismatch and reduced survival after heart transplantation.
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