A simulation of the NiO/Ag interface with point defects

The NiO/Ag interface has been modelled using established simulation techniques, which have been modified to include the image interactions between the oxide ions and the induced charge in the metal. The energies of point defects near the interface were calculated and it was found that the surface rumpling was such that defects with a negative net charge were favoured. This will result in a space charge layer with excess cation vacancies which will cancel the interfacial potential. A low energy interface was modelled in which the cation sub-lattice of the second oxide plane was saturated with vacancies and Ni3+. ions. Such a structure may be responsible for the observed excess of oxygen near the NiO/Ni interface, and also for the low wetting angles of metals on NiO, compared with MgO

Study of the pd→3HeK+K−pd\to ^3\textrm{He} K^+K^- and pd→3Heϕpd\to ^3\textrm{He} \phi reactions close to threshold

Two--kaon production in proton--deuteron collisions has been studied at three energies close to threshold using a calibrated magnetic spectrograph to measure the final $^3$He and a vertex detector to measure the $K^+K^-$ pair. Differential and total cross sections are presented for the production of $\phi$--mesons, decaying through $\phi\to K^+K^-$, as well as for prompt $K^+K^-$ production. The prompt production seems to follow phase space in both its differential distributions and in its energy dependence. The amplitude for the $pd\to ^3${He}$\phi$ reaction varies little for excess energies below 22 MeV and the value is consistent with that obtained from a threshold measurement. The angular distribution of the $K^+K^-$ decay pair shows that near threshold the $\phi$--mesons are dominantly produced with polarization $m=0$ along the initial proton direction. No conclusive evidence for $f_0(980)$ production is found in the data.Comment: 13 figure

One-Year Outcomes of Open Lumbar Discectomy in Shahid Bahonar Hospital, Kerman, Iran, 2012

Background: Despite the frequency of lumbar disc surgery in Iran, just few studies have been undertaken in this respect. So, the present study aimed to investigate one-year outcomes of lumbar discectomy in Shahid Bahonar Hospital, Kerman, Iran. Methods: All the patients referred to this hospital in 2012 to have lumbar disc operation were entered the study. Then, patients with lumbar canal stenosis were excluded. Pain intensity, and disability were studied before and 1, 4, and 12 months after the surgery based on visual analog scale (VAS), and Oswestry disability index (ODI), respectively. Results: 169 patients with the mean age of 41.6 ± 9.8 years participated in this study. Before the surgery, pain intensity and disability index were 88.2 ± 9.3 and 73.4 ± 8.5, respectively. Twelve months after the surgery, pain intensity decreased to 27.3 ± 4.3, disability index decreased to 23.6 ± 6.2, and the level of patient satisfaction was 92%. Conclusion: In this study, level of patient satisfaction, and decrease in pain intensity and disability index were somewhat similar to those of other studies; however, further multicenter studies including larger numbers of participants are recommended. Keywords Discectomy; Spine; outcome; Lumba

Experimental study of the pd(d p) → 3 He ππ reactions close to threshold

New experimental data on the pd → 3 He π+π− reaction obtained with the COSY-MOMO detector below the three-pion threshold are presented. The reaction was also studied in inverse kinematics with a deuteron beam and the higher counting rates achieved were especially important at low excess energies. The comparison of these data with inclusive pd → 3 He X0 rates allowed estimates also to be made of π0π0 production. The results confirm our earlier findings that, close to threshold, there is no enhancement at low excitation energies in the π+π− system, where the data seem largely suppressed compared with phase space. Possible explanations for this behavior, such as strong p waves in the π+π− system or the influence of two-step processes, are explored

Migration control: A distance compensation strategy in ants

©The Author(s) 2016. This article is published with open access at Springerlink.com. Migratory behaviour forms an intrinsic part of the life histories of many organisms but is often a high-risk process. Consequently, varied strategies have evolved to negate such risks, but empirical data relating to their functioning are limited. In this study, we use the model system of the househunting ant Temnothorax albipennis to demonstrate a key strategy that can shorten migration exposure times in a group of social insects. Colonies of these ants frequently migrate to new nest sites, and due to the nature of their habitat, the distances over which they do so are variable, leading to fluctuating potential costs dependent on migration parameters. We show that colonies of this species facultatively alter the dynamics of a migration and so compensate for the distance over which a given migration occurs. Specifically, they achieve this by modulating the rate of ‘tandem running’, in which workers teach each other the route to a new nest site. Using this method, colonies are able to engage a larger number of individuals in the migration process when the distance to be traversed is greater, and furthermore, the system appears to be based on perceived encounter rate at the individual level. This form of decentralised control highlights the adaptive nature of a behaviour of ecological importance, and indicates that the key to its robustness lies in the use of simple rules. Additionally, our results suggest that such coordinated group reactions are central to achieving the high levels of ecological success seen in many eusocial organisms

Intraocular colchicine inhibits competition between resident and foreign optic axons for functional connections in the doubly innervated goldfish optic tectum

After unilateral optic tectum ablation in the goldfish, regenerating optic axons grow into the optic layers of the remaining ipsilateral tectal lobe and regain visual function. The terminal arbors of the foreign fibers are initially diffusely distributed among the resident optic axons, but within two months the axon terminals from each retina are seen to segregate into irregular ocular dominance patches. Visual recovery is delayed until after segregation. This suggests that the foreign fibers compete with the residents for tectal targets and that the segregation of axon terminations is an anatomical characteristic of the process. Here we investigate whether inhibiting axonal transport in the resident fibers inhibits competition with foreign fibers. The eye contralateral to the intact tectal lobe received a single injection of 0.1 [mu]g colchicine, which does not block vision with the intact eye. We measured visual function using a classical conditioning technique. Segregation of axon terminations was examined shortly following visual recovery by autoradiography. The no-drug control fish showed reappearance of vision with the experimental eye at 9 weeks postoperatively and ocular dominance patches were well developed. Colchicine administered to the intact eye (resident fibers) several weeks postsurgery decreased the time to reappearance of vision with the experimental eye by several weeks. Autoradiography revealed some signs of axonal segregation but the labeled foreign axons were mainly continuously distributed. Administration of colchicine at the time of tectum ablation, or of lumicolchicine at two weeks postoperatively produced normal visual recovery times. Fast axonal transport of 3H-labeled protein was inhibited by 1.0 and 0.5 [mu]g but not by 0.1 [mu]g of colchicine or by 1.0 [mu]g of lumicolchicine. Previous studies showed that while 0.1 [mu]g of colchicine does not block vision it is sufficient to inhibit axonal regeneration following optic nerve crush. We conclude that two retinas can functionally innervate one tectum without forming conspicuous ocular dominance columns, and that the ability of residents to compete with the in-growing foreign axons is very sensitive to inhibition of axoplasmic transport or other processes that are inhibited by intraocular colchicine.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26010/1/0000077.pd