Ground State of Quantum Jahn-Teller Model: Selftrapping vs Correlated Phonon-assisted Tunneling

Ground state of the quantum Jahn-Teller model with broken rotational symmetry was investigated by the variational approach in two cases: a lattice and a local ones. Both cases differ by the way of accounting for the nonlinearity hidden in the reflection-symmetric Hamiltonian. In spite of that the ground state energy in both cases shows the same features: there appear two regions of model parameters governing the ground state: the region of dominating selftrapping modified by the quantum effects and the region of dominating phonon-assisted tunneling (antiselftrapping). In the local case (i) the effect of quantum fluctuations and anharmonicity due to the two-mode correlations is up to two orders larger than contributions due to the reflection effects of two-center wave function; (ii) the variational results for the ground state energy were compared with exact numerical results. The coincidence is the better the more far away from the transition region at the E$\otimes$e symmetry where the variational approach fails.Comment: 18 pages, 7 figures, published in Adv.in Quantum Chemistr

Observation of Babbling in Children with Cochlear Implant at the Age of 12 to 21 months

A delay in canonical babbling can predict a later delay in speech development. Infants with normal hearing establish canonical babbling before 10 months of age. Children who receive cochlear implant (CI) begin to babble approximately four months after surgery. This study observed babbling children with cochlear implant. The hypothesis was that children who had had CI for four months begun to use canonical babbling and that the development thereafter did not differ from children with normal hearing. Six toddlers between 12 and 21 months participated. The babbling was judged from a validated observation form and compared with data from children with normal hearing. Intra- and interobserver reliability was good (0,783 to 0,988). Four out of the six children with CI (hearing age>4 months) had canonical babbling and there were no significant differences in articulation in comparison to children with normal hearing. There was a significant correlation between the age at implantation and the amount of canonical babbling in the children with CI. The method of observation was reliable and the results support the hypothesis.Försenad start av stavelsejoller kan predicera förseningar i tal- och språkutvecklingen. För normalhörande barn etableras stavelseproduktionen före 10 månaders ålder vilket inte är fallet hos döva barn. Barn som får cochleaimplantat (CI) börjar jollra cirka fyra månader efter operation och verkar ha en jollerutveckling liknande normalhörandes. Studiens syfte var att observera joller och artikulation på småbarn med CI utifrån ett validerat observationsformulär. Studiens hypotes var att barn med en hörselålder på mer än 4 månader har stavelsejoller och att jollerproduktionen inte skiljer sig nämnvärt från normalhörandes. Sex barn mellan 12 och 21 månader deltog. Jollret bedömdes utifrån ett validerat observationsformulär och jämfördes med data från normalhörande. Intra- och interbedömarreliabilitet var god (0,783 till 0,988). Fyra av sex barn med CI (hörselålder>4 månader) hade stavelsejoller och det fanns inga signifikanta skillnader beträffande artikulation jämfört med normalhörande barn. Det fanns ett signifikant samband mellan hörselålder och mängd stavelsejoller. Observationsmetoden var tillförlitlig och resultaten stöder studiens hypotes

Characterization of Venusian atmospheric dynamics using Venus Express images and ground-based observations

The equatorial atmosphere of Venus rotates 60 times faster than the solid planet, a poorly understood phenomenon known as superrotation. Kelvin-like waves have been hypothesized to maintain the superrotation against dissipation, and the planet- scale “Y-feature”, a transient cloud feature, is likely their visible manifestation. In order to detect these waves, the spatial and temporal evolution of Venus’ atmosphere as a whole must be better characterized on long time scales. Using data from the Venus Monitoring Camera on board Venus Express, we have found yearly average zonal wind profiles by using Correlation Image Velocimetry. In order to better char- acterize the measurement uncertainty and separate it from real variation compared to using the standard deviation, we have developed a method of uncertainty calcula- tion using correlation fields. We observed a consistent trend of increasing zonal wind velocity, about 20 ms−1 over eight years of observation, in the area that the Y-feature is present, which may be caused by Kelvin-like waves accelerating the mean flow. This variation is comparable to the standard deviation and uncertainty, and thus cannot be definitively confirmed. Our new method of uncertainty calculation gave comparable uncertainty to the standard deviation and future work will be needed for improvement in the uncertainty calculation

Flotation—A New Method to Circumvent PCR Inhibitors in the Diagnosis of Lawsonia intracellularis

The obligate intracellular bacterium Lawsonia intracellularis causes enteritis and poor growth in weaned pigs. Cultivation is difficult and diagnosis ante mortem is mainly based on techniques such as polymerase chain reaction. However, false negative results caused by the presence of PCR-inhibitory factors constitute a problem. This study aimed to develop and evaluate a new technique, flotation, to separate L. intracellularis from inhibitors in faeces prior to PCR. The technique was evaluated by comparison to two previously evaluated and commonly used methods, preparation by boiling lysate combined with nested PCR and preparation by a commercial kit combined with conventional PCR. Continuous density centrifugation of faecal samples containing L. intracellularis suggested the buoyant density of the microbe to be between 1.064 and 1.077 g/mL. Several flotation setups were tested to achieve optimal separation of the microbe from inhibitors and faecal particles. The finally selected setup floated whole L. intracellularis from the application site at the bottom to the upper part of the gradient while inhibitory components mainly remained in the bottom. PCR was performed directly on material recovered from the upper interphase. The method was evaluated on 116 clinical samples. As compared to sample preparation by boiling combined with nested PCR, fewer samples were inhibited but also fewer positives were identified. In comparison to preparation by a commercial kit combined with conventional PCR, presently used for routine diagnosis, similar results were obtained. However, the new method was comparably faster to perform. The new method, based on flotation of Lawsonia intracellularis combined with conventional PCR, was well suited for routine diagnosis

Electron correlations, spontaneous magnetization and momentum density in quantum dots

The magnetization of quantum dots is discussed in terms of a relatively simple but exactly solvable model Hamiltonian. The model predicts oscillations in spin polarization as a function of dot radius for a fixed electron density. These oscillations in magnetization are shown to yield distinct signature in the momentum density of the electron gas, suggesting the usefulness of momentum resolved spectroscopies for investigating the magnetization of dot systems. We also present variational quantum Monte Carlo calculations on a square dot containing 12 electrons in order to gain insight into correlation effects on the interactions between like and unlike spins in a quantum dot.Comment: 6 pages, 4 figure

Learning Efficient Navigation in Vortical Flow Fields

Efficient point-to-point navigation in the presence of a background flow field is important for robotic applications such as ocean surveying. In such applications, robots may only have knowledge of their immediate surroundings or be faced with time-varying currents, which limits the use of optimal control techniques for planning trajectories. Here, we apply a novel Reinforcement Learning algorithm to discover time-efficient navigation policies to steer a fixed-speed swimmer through an unsteady two-dimensional flow field. The algorithm entails inputting environmental cues into a deep neural network that determines the swimmer's actions, and deploying Remember and Forget Experience replay. We find that the resulting swimmers successfully exploit the background flow to reach the target, but that this success depends on the type of sensed environmental cue. Surprisingly, a velocity sensing approach outperformed a bio-mimetic vorticity sensing approach by nearly two-fold in success rate. Equipped with local velocity measurements, the reinforcement learning algorithm achieved near 100% success in reaching the target locations while approaching the time-efficiency of paths found by a global optimal control planner.Comment: 6 pages, 6 figure

Предметно-деятельное содержание патриотизма белорусских студентов

The municipal identities and the absence of shared benefits-A case of municipal cooperationbetween Norrköping and Linköping on issues of regional airports.This is a bachelor thesis concerning airports in the region of Östergötland and policy network cooperation between the municipal Norrköping and Linköping. The municipalities have numerous times interacted in other fields of the political administration. The thesis investigates the steps that have been taken by the municipalities since the last reports that were made in this matter. Why there have not been any achievements in interactions and what may happen in the future to these airports. The result is based on empirical evidence collected from an interview study; the respondents in the interviews are politicians and public officials in both municipals.The thesis shows that the implementation process of policy networks between the municipalities have been lingering and difficult. Politicians from the municipal of Linköping have not seen the benefits of a jointly owned operating company for the airports, while the politicians from the municipal of Norrköping has not worked proactive in the matter. The final conclusion of the thesis is that the two regional airports today are to varied in their structures to be able to corporate and the only output that came from the reports in this matter was an informal partnership agreement in marketing