Non-adiabatic corrections to elastic scattering of halo nuclei

We derive the formalism for the leading order corrections to the adiabatic approximation to the scattering of composite projectiles. Assuming a two-body projectile of core plus loosely-bound valence particle and a model (the core recoil model) in which the interaction of the valence particle and the target can be neglected, we derive the non-adiabatic correction terms both exactly, using a partial wave analysis, and using the eikonal approximation. Along with the expected energy dependence of the corrections, there is also a strong dependence on the valence-to-core mass ratio and on the strength of the imaginary potential for the core-target interaction, which relates to absorption of the core in its scattering by the target. The strength and diffuseness of the core-target potential also determine the size of the corrections. The first order non-adiabatic corrections were found to be smaller than qualitative estimates would expect. The large absorption associated with the core-target interaction in such halo nuclei as Be11 kills off most of the non-adiabatic corrections. We give an improved estimate for the range of validity of the adiabatic approximation when the valence-target interaction is neglected, which includes the effect of core absorption. Some consideration was given to the validity of the eikonal approximation in our calculations.Comment: 14 pages with 10 figures, REVTeX4, AMS-LaTeX v2.13, submitted to Phys. Rev.

Discrete Accidental Symmetry for a Particle in a Constant Magnetic Field on a Torus

A classical particle in a constant magnetic field undergoes cyclotron motion on a circular orbit. At the quantum level, the fact that all classical orbits are closed gives rise to degeneracies in the spectrum. It is well-known that the spectrum of a charged particle in a constant magnetic field consists of infinitely degenerate Landau levels. Just as for the $1/r$ and $r^2$ potentials, one thus expects some hidden accidental symmetry, in this case with infinite-dimensional representations. Indeed, the position of the center of the cyclotron circle plays the role of a Runge-Lenz vector. After identifying the corresponding accidental symmetry algebra, we re-analyze the system in a finite periodic volume. Interestingly, similar to the quantum mechanical breaking of CP invariance due to the $\theta$-vacuum angle in non-Abelian gauge theories, quantum effects due to two self-adjoint extension parameters $\theta_x$ and $\theta_y$ explicitly break the continuous translation invariance of the classical theory. This reduces the symmetry to a discrete magnetic translation group and leads to finite degeneracy. Similar to a particle moving on a cone, a particle in a constant magnetic field shows a very peculiar realization of accidental symmetry in quantum mechanics.Comment: 25 pages, 2 figure

Sharing data from clinical trials: the rationale for a controlled access approach.

The move towards increased transparency around clinical trials is welcome. Much focus has been on under-reporting of trials and access to individual patient data to allow independent verification of findings. There are many other good reasons for data sharing from clinical trials. We describe some key issues in data sharing, including the challenges of open access to data. These include issues in consent and disclosure; risks in identification, including self-identification; risks in distorting data to prevent self-identification; and risks in analysis. These risks have led us to develop a controlled access policy, which safeguards the rights of patients entered in our trials, guards the intellectual property rights of the original researchers who designed the trial and collected the data, provides a barrier against unnecessary duplication, and ensures that researchers have the necessary resources and skills to analyse the data

Effects of an induced three-body force in the incident channel of (d,p) reactions

A widely accepted practice for treating deuteron breakup in $A(d,p)B$ reactions relies on solving a three-body $A+n+p$ Schr\"odinger equation with pairwise $A$-$n$, $A$-$p$ and $n$-$p$ interactions. However, it was shown in [Phys. Rev. C \textbf{89}, 024605 (2014)] that projection of the many-body $A+2$ wave function into the three-body $A+n+p$ channel results in a complicated three-body operator that cannot be reduced to a sum of pairwise potentials. It contains explicit contributions from terms that include interactions between the neutron and proton via excitation of the target $A$. Such terms are normally neglected. We estimate the first order contribution of these induced three-body terms and show that applying the adiabatic approximation to solving the $A+n+p$ model results in a simple modification of the two-body nucleon optical potentials. We illustrate the role of these terms for the case of $^{40}$Ca($d,p$)$^{41}$Ca transfer reactions at incident deuteron energies of 11.8, 20 and 56 MeV, using several parameterisations of nonlocal optical potentials.Comment: 7 pages, 2 figures. Publication due in Phys. Rev.

Molecular surveillance of Theileria parasites of livestock in Oman

Background: Theileriosis is one of the most prevalent infectious diseases of livestock in the Arabian Peninsula, and causes high rates of mortality and morbidity in sheep and cattle. However, there is a paucity of information on the distribution of Theileria spp. over the whole region and their impact on different hosts. The present study carried out a country-wide molecular survey for Theileria spp. of livestock in Oman across four governorates. The aim of the survey was to define the prevalence of Theileria spp. in cattle, sheep and goats, highlight risk factors for infection and identify the main tick species involved in parasite transmission. Material and methods: A total of 2020 animals were examined in the survey consisting of sheep [n = 592], goats [n = 981] and cattle [n = 447]. All three species were raised and co-grazed on the same farms. Theileria parasites were detected using PCR-RFLP and RLB of the 18S rRNA gene. Cloning and sequencing of the 18S rRNA was carried out on 11 T. lestoquardi isolates from Ash-Sharqiyah, and Ad-Dhahira governorates, and phylogenetic relationships were inferred using additional sequences of T. lestoquardi, T. annulata and T. ovis available in GenBank. Results: Theileria spp. prevalence was 72.3%, 36.7% and 2.7% among cattle, sheep and goats, respectively. Strong similarity in results was obtained using RLB and PCR-RFLP for detection of Theileria spp. however, RLB detected a higher rate of mixed infection than PCR-RFPL (P < 0.001). Theileria annulata was the only parasite detected in cattle, while sheep and goats carried T. ovis, T. lestoquardi and T. annulata as well as Theileria spp. OT1. Of the four Theileria spp. detected in small ruminants, overall T. ovis was most prevalent (sheep [33.4%], goats [2.0%]), whereas T. lestoquardi was less prevalent (sheep [22.0%], goats [0.5%]). A large proportion of infected sheep (19%) carried mixed infection of T. ovis and T. lestoquardi. However, single T. lestoquardi infections (3.0%) were less prevalent than T. ovis infections (14.5%). Risk of Theileria spp. infection was significantly higher for exotic breeds, relative to native breeds, of cattle (p = 0.00002) and sheep (p = 0.005). Phylogenetic analysis placed T. lestoquardi in Oman in the same clade as other T. lestoquardi strains isolated from the same regional area (Iraq and Iran). The main tick species, identified on the examined animals, Hyalomma anatolicum, was widely distributed and was found in all of the surveyed governorates. Conclusion: Theileria spp. are widespread in Oman with variable prevalence detected in different regions. Two economically important hosts, cattle and sheep are at high risk from virulent T. annulata and T. lestoquardi, respectively. The survey indicates extensive exposure to ticks and transmission of infection that has a significant economic impact. The higher prevalence of T. lestoquardi as mixed rather than single infection requires further investigation

Developmental Changes in Infants' Categorization of Anger and Disgust Facial Expressions

For decades, scholars have examined how children first recognize emotional facial expressions. This research has found that infants younger than 10 months can discriminate negative, within-valence facial expressions in looking time tasks, and children older than 24 months struggle to categorize these expressions in labeling and free-sort tasks. Specifically, these older children, and even adults, consistently misidentify disgust expressions as anger. Although some scholars have hypothesized that young infants would also be unable to categorize anger and disgust expressions, this question has not been empirically tested. In addition, very little research has examined developmental changes in infants' perceptual categorization abilities with high arousal, within-valence emotions. For this reason, the current study tested 10- and 18-month-olds in a looking time task and found that both age groups could perceptually categorize anger and disgust facial expressions. Furthermore, 18-month-olds showed a heightened sensitivity to novel anger expressions, suggesting that, over the second year of life, infants' emotion categorization skills undergo developmental change. These findings are the first to demonstrate that young infants can categorize anger and disgust facial expressions and to document how this skill develops and changes over time