Role of Multichance Fission in the Description of Fission-Fragment Mass Distributions at High Energies

Fission-fragment mass distributions were measured for U237-240, Np239-242, and Pu241-244 populated in the excitation-energy range from 10 to 60 MeV by multinucleon transfer channels in the reaction O18+U238 at the Japan Atomic Energy Agency tandem facility. Among them, the data for U240 and Np240,241,242 were observed for the first time. It was found that the mass distributions for all the studied nuclides maintain a double-humped shape up to the highest measured energy in contrast to expectations of predominantly symmetric fission due to the washing out of nuclear shell effects. From a comparison with the dynamical calculation based on the fluctuation-dissipation model, this behavior of the mass distributions was unambiguously attributed to the effect of multichance fission

Testing microscopically derived descriptions of nuclear collectivity : Coulomb excitation of 22Mg

Many-body nuclear theory utilizing microscopic or chiral potentials has developed to the point that collectivity might be studied within a microscopic or ab initio framework without the use of effective charges; for example with the proper evolution of the E2 operator, or alternatively, through the use of an appropriate and manageable subset of particle–hole excitations. We present a precise determination of E2 strength in 22Mg and its mirror 22Ne by Coulomb excitation, allowing for rigorous comparisons with theory. No-core symplectic shell-model calculations were performed and agree with the new B(E2) values while in-medium similarity-renormalization-group calculations consistently underpredict the absolute strength, with the missing strength found to have both isoscalar and isovector components. The discrepancy between two microscopic models demonstrates the sensitivity of E2 strength to the choice of many-body approximation employed

Atypical antipsychotic augmentation in SSRI treatment refractory obsessive-compulsive disorder: a systematic review and meta-analysis

Background: In 2006, the National Institute of Clinical and Health Excellence (NICE) guidelines for Obsessive Compulsive Disorder (OCD) recommended anti-psychotics as a class for SSRI treatment resistant OCD. The article aims to systematically review and conduct a meta-analysis on the clinical effectiveness of atypical anti-psychotics augmenting an SSRI. Methods: Studies that were double-blind randomized controlled trials of an atypical antipsychotic against a placebo, for a minimum of 4 weeks, in adults with OCD, were included. Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores were the primary outcome measure. Inclusion criteria included Y-BOCS score of 16 or more and at least one adequate trial of a SSRI or clomipramine for at least 8 weeks prior to randomization. Data sources included Medline, Embase, PsycINFO, Cochrane Database of Systematic Reviews (CDSR), trial registries and pharmaceutical databases and manufacturers up to September 2013. Forest-plots were drawn to display differences between drug and placebo on the Y-BOCS. Results: Two studies found aripiprazole to be effective in the short-term. There was a small effect-size for risperidone or anti-psychotics in general in the short-term. We found no evidence for the effectiveness of quetiapine or olanzapine in comparison to placebo. Conclusions: Risperidone and aripiprazole can be used cautiously at a low dose as an augmentation agent in non-responders to SSRIs and CBT but should be monitored at 4 weeks to determine efficacy

Coulomb excitation of the ∣Tz∣=12,A=23|T_z|=12, A=23 mirror pair

Background: Electric-quadrupole ($E2$) strengths relate to the underlying quadrupole deformation of a nucleus and present a challenge for many nuclear theories. Mirror nuclei in the vicinity of the line of $N=Z$ represent a convenient laboratory for testing deficiencies in such models, making use of the isospin-symmetry of the systems. Purpose: Uncertainties associated with literature $E2$ strengths in \textsuperscript{23}Mg are some of the largest in $T_z=\left|\frac{1}{2}\right|$ nuclei in the $sd$-shell. The purpose of the present work is to improve the precision with which these values are known, to enable better comparison with theoretical models. Methods: Coulomb-excitation measurements of $^{23}$Mg and $^{23}$Na were performed at the TRIUMF-ISAC facility using the TIGRESS spectrometer. They were used to determine the $E2$ matrix elements of mixed $E2$/$M1$ transitions. Results: Reduced $E2$ transition strengths, $B(E2)$, were extracted for \textsuperscript{23}Mg and \textsuperscript{23}Na. Their precision was improved by factors of approximately six for both isotopes, while agreeing within uncertainties with previous measurements. Conclusions: A comparison was made with both shell-model and {\it ab initio} valence-space in-medium similarity renormalization group calculations. Valence-space in-medium similarity-renormalization-group calculations were found to underpredict the absolute $E2$ strength - in agreement with previous studies

Identification of significant E0E0 strength in the 22+→21+2^+_2 \rightarrow 2^+_1 transitions of 58,60,62^{58, 60, 62}Ni

The $E0$ transition strength in the $2^+_2 \rightarrow 2^+_1$ transitions of $^{58,60,62}$Ni have been determined for the first time following a series of measurements at the Australian National University (ANU) and the University of Kentucky (UK). The CAESAR Compton-suppressed HPGe array and the Super-e solenoid at ANU were used to measure the $\delta(E2/M1)$ mixing ratio and internal conversion coefficient of each transition following inelastic proton scattering. Level half-lives, $\delta(E2/M1)$ mixing ratios and $\gamma$-ray branching ratios were measured at UK following inelastic neutron scattering. The new spectroscopic information was used to determine the $E0$ strengths. These are the first $2^+ \rightarrow 2^+$ $E0$ transition strengths measured in nuclei with spherical ground states and the $E0$ component is found to be unexpectedly large; in fact, these are amongst the largest $E0$ transition strengths in medium and heavy nuclei reported to date

Identification of Significant \u3cem\u3eE\u3c/em\u3e0 Strength in the 2\u3csub\u3e2\u3c/sub\u3e\u3csup\u3e+\u3c/sup\u3e → 2\u3csub\u3e1\u3c/sub\u3e\u3csup\u3e+\u3c/sup\u3e Transitions of \u3csup\u3e58,60,62\u3c/sup\u3eNi

The E0 transition strength in the 22+ → 21+ transitions of 58,60,62Ni have been determined for the first time following a series of measurements at the Australian National University (ANU) and the University of Kentucky (UK). The CAESAR Compton-suppressed HPGe array and the Super-e solenoid at ANU were used to measure the δ(E2/M1) mixing ratio and internal conversion coefficient of each transition following inelastic proton scattering. Level half-lives, δ(E2/M1) mixing ratios and γ-ray branching ratios were measured at UK following inelastic neutron scattering. The new spectroscopic information was used to determine the E0 strengths. These are the first 2+ → 2+ E0 transition strengths measured in nuclei with spherical ground states and the E0 component is found to be unexpectedly large; in fact, these are amongst the largest E0 transition strengths in medium and heavy nuclei reported to date