4,205 research outputs found

    Investigation of in-plane nuclear field formation in single self-assembled quantum dots

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    We studied the formation mechanism of the in-plane nuclear field in single self-assembled In0.75_{0.75}Al0.25_{0.25}As/Al0.3_{0.3}Ga0.7_{0.7}As quantum dots. The Hanle curves with an anomalously large width and hysteretic behavior at the critical transverse magnetic field were observed in many single quantum dots grown in the same QD sample. In order to explain the anomalies in the Hanle curve indicating the formation of a large nuclear field perpendicular to the photo-injected electron spin polarization, we propose a new model based on the current phenomenological model for dynamic nuclear spin polarization. The model includes the effects of the nuclear quadrupole interaction and the sign inversion between in-plane and out-of-plane g-factors, and the model calculations reproduce successfully the characteristics of the observed anomalies in the Hanle curves.Comment: 7 pages, 6 figure

    Precise measurements of electron and hole g-factors of single quantum dots by using nuclear field

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    We demonstrated the cancellation of the external magnetic field by the nuclear field at one edge of the nuclear polarization bistability in single InAlAs quantum dots. The cancellation for the electron Zeeman splitting gives the precise value of the hole g-factor. By combining with the exciton g-factor that is obtained from the Zeeman splitting for linearly polarized excitation, the magnitude and sign of the electron and hole g-factors in the growth direction are evaluated.Comment: 3 pages, 2 figure

    Pathogenesis of dystonia: is it of cerebellar or basal ganglia origin?

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    Dystonia is a disorder of motor programmes controlling semiautomatic movements or postures, with clinical features such as sensory trick, which suggests sensorimotor mismatch as the basis. Dystonia was originally classified as a basal ganglia disease. It is now regarded as a 'network' disorder including the cerebellum, but the exact pathogenesis being unknown. Rare autopsy studies have found pathology both in the striatum and the cerebellum, and functional disorganisation was reported in the somatosensory cortex in patients. Recent animal studies showed physiologically tight disynaptic connections between the cerebellum and the striatum. We review clinical evidence in light of this new functional interaction between the cerebellum and basal ganglia, and put forward a hypothesis that dystonia is a basal ganglia disorder that can be induced by aberrant afferent inputs from the cerebellum

    Structural insights into initial and intermediate steps of the ribosome-recycling process

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    The ribosome recycling factor (RRF) and elongation factor G (EF-G) disassemble the 70S post-termination complex (PoTC) into mRNA, tRNA, and two ribosomal subunits. We have determined cryo-EM structures of the PoTC•RRF complex, with and without EF-G. We find that domain II of RRF initially interacts with universally conserved residues of the 23S rRNA helices 43 and 95, and protein L11 within the 50S ribosomal subunit. Upon EF-G binding, both RRF and tRNA are driven toward the tRNA-exit (E) site, with a large rotational movement of domain II of RRF toward the 30S ribosomal subunit. During this intermediate step of the recycling process, domain II of RRF and domain IV of EF-G adapt unusual conformations. Furthermore, binding of EF-G to the PoTC•RRF complex reverts the ribosome from ratcheted to unratcheted state. These results suggest that (i) the ribosomal intersubunit reorganizations upon RRF binding and subsequent EF-G binding could be instrumental in destabilizing the PoTC, and (ii) the modes of action of EF-G during tRNA translocation and ribosome recycling steps are markedly different

    Characterisation of an analogue liquid for hydrodynamic studies of gas-ionic liquid flows

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    Ionic liquids are liquid salts at low temperatures (normally less than 100°C). They are powerful solvents with very low vapour pressure. They have great potentials in many applications such as gas absorption and chemical synthesis. However, they are expensive. This limits extensive studies towards establishing phenomenological models. To address this limitation, an analogue liquid, with properties similar to an ionic liquid, has been identified which on the grounds of cost and safety appears to be suitable. In this paper, the hydrodynamic behaviour of an ionic liquid in a bubble column is compared with those of water and other liquids with similar physical properties. Average gas holdup, bubble coalescence, bubble size and specific interfacial area with different liquids are examined. Gas hold-up was determined by monitoring the change of conductivity between two flush mounted rings. The differences in bubble size and coalescence are revealed by analysing the stills taken from a high speed video camera. The dominant flow pattern in a small diameter column with ionic liquids or other fluids having similar viscosity is slug flow. The small bubbles in the liquid slugs make a smaller contribution to the specific interfacial area than Taylor bubbles. It is observed that Taylor bubbles can coalesce. The hydrodynamics of an ionic liquid in a bubble column can be estimated from that of a fluid with similar physical properties

    The Impact of Suspect Descriptions in University Crime Reports on Racial Bias

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    Crime reports often include suspect descriptions to alert community members and aid in police investigations. However, vague descriptions of suspects with racial identifiers can potentially do more harm than good. We first conducted an archival study to examine the frequency of reporting suspect race, as well as the relationship between the inclusion of race and the likelihood that the suspect was caught. Then we conducted an experimental study to examine how reporting race may affect overt and subtle racial attitudes. We found no significant relationship between the racial identification of a suspect and the likelihood that the suspect was caught in our archival study. However, our findings from the experimental study demonstrate increased overt and subtle racial bias towards Black people when comparing participants who read a crime report with a Black suspect to those who read one about a suspect with no racial identification. Implications and future directions are discussed

    Augmented Reality in Smart Cities: A Multimedia Approach

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    Intro: This paper presents an advance overview of utilizing Augmented Reality (AR) in smart cities. Although, Smart cities contain six major aspects (mobility, economy, government, environment, living, and people), this paper focuses on three of them that have more potentiality in using virtual assistant (mobility, environment, and living). Methodology: Presenting a state-of-the-art review studies undertake between 2013 and 2017, which is driven from highlighted libraries is the aim of this research. After exact examine, 15 emphasized studies are chosen to divide the main aspects while 120 selective articles are supporting them. These categorizes have been critically compared with an aim, method and chronological perspectives. Results: First of All, Environmental issues (Museums industry) attract the most attention of researchers while the living issues (maintenance) have lower significant compare t latter and mobility (indoor-outdoor navigation) attract the least. Moreover, a close connection between academic and industry fields is going to be created. Conclusions: it has been concluded that, because of economic advantages, utilizing AR technology has improved in the tourism and maintenance. Moreover, until now, most of studies try to prove their concept rather than illustrate well stablished analytic approach. Because of hardware and software improvement, it is essential for the future studies to evaluate their hypothesis in a real urban context
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