Spin-orbital phase synchronization in the magnetic field-driven electron dynamics in a double quantum dot

We study the dynamics of an electron confined in a one-dimensional double quantum dot in the presence of driving external magnetic fields. The orbital motion of the electron is coupled to the spin dynamics by spin orbit interaction of the Dresselhaus type. We derive an effective time-dependent Hamiltonian model for the orbital motion of the electron and obtain a synchronization condition between the orbital and the spin dynamics. From this model we deduce an analytical expression for the Arnold tongue and propose an experimental scheme for realizing the synchronization of the orbital and spin dynamics.Comment: 6 figures, 14 page

Strain-induced insulator state in La_0.7Sr_0.3CoO_3

We report on the observation of a strain-induced insulator state in ferromagnetic La_0.7Sr_0.3CoO_3 films. Tensile strain above 1% is found to enhance the resistivity by several orders of magnitude. Reversible strain of 0.15% applied using a piezoelectric substrate triggers huge resistance modulations, including a change by a factor of 10 in the paramagnetic regime at 300 K. However, below the ferromagnetic ordering temperature, the magnetization data indicate weak dependence on strain for the spin state of the Co ions. We interpret the changes observed in the transport properties in terms of a strain-induced splitting of the Co e_g levels and reduced double exchange, combined with a percolation-type conduction in an electronic cluster state

Reversible strain effect on the magnetization of LaCoO3 films

The magnetization of ferromagnetic LaCoO3 films grown epitaxially on piezoelectric substrates has been found to systematically decrease with the reduction of tensile strain. The magnetization change induced by the reversible strain variation reveals an increase of the Co magnetic moment with tensile strain. The biaxial strain dependence of the Curie temperature is estimated to be below 4K/% in the as-grown tensile strain state of our films. This is in agreement with results from statically strained films on various substrates

Peripheral Tolerance of CD8 T Lymphocytes

SummaryWhereas high-avidity recognition of peptide-MHC complexes by developing T cells in the thymus results in deletion and promotes self-tolerance, such recognition by mature T cells in the periphery results in activation and clonal expansion. This dichotomy represents the basis of a dilemma that has stumped immunologists for many years, how are self-specific T cells tolerized in the periphery? There appear to be two important criteria used to achieve this goal. The first is that in the absence of inflammatory pathogens, tolerance is promoted when T cells recognize antigen presented by quiescent dendritic cells (DCs) expressing low levels of costimulatory molecules. A second critical factor that defines “self” and drives tolerance through deletion, anergy, or suppression is the persistence of antigen

Design Considerations for an Orbital NonPropulsive Vent System

Minimizing of attitude disturbances during critical maneuvers in space is extremely important to the success of present and future aerospace missions. Thus, a means is needed to ensure that definite attitude positions can be maintained during specific phases of a mission and in some cases indefinitely. To fulfill this requirement, excess or residual propellant vapors and waste gases must be removed with minimum impulse unbalances imparted to the vehicle. The obvious method of accomplishing this is to employ a vent system that dissipates the impulse generated by the various effluents in a nonpropulsive manner. Such nonpropulsive vent (NPV) systems have been designed, installed and flown on several S-IV and S-IVB stages of the Saturn Launch Vehicles. This system was the first of its kind to be tested in orbit, and the data from these flights clearly substantiates the design adequacy of the system. Design considerations and the overall approach in resolving the requirements of this system are discussed in detail

Do Gang Injunctions Reduce Violent Crime? Four Tests in Merseyside, UK

Research Question: Did gang members and gangs named by police in four separate court-ordered 24-month injunctions, issued at different times, reduce the frequency and harm of crimes they committed, and suffer fewer crimes against themselves as well? Data: The study examined criminal histories of 36 members of four gangs for a 36-month period before and a 36-month period after their respective injunctions. Data also included records of crimes committed against the gang members in the same time periods. Criminal activity was measured by arrests, station interviews, fixed penalty notices and summonses. Days offenders spent in custody, which rose during the gang injunction periods, were removed from denominators calculating rates, so that the estimates of changes in offender behaviour and victimisations are all based on their days at liberty and out of prison or jail. Methods: The study compared the magnitude of change in both individual-level and gang-level measures of crime and victimisation from before to after the issuance of the injunction as ‘natural quasi-experiments’, with comparisons made to other gangs in Liverpool which had not been subjects of injunctions. Findings: Across all 36 gang members, their individual offending counts dropped by 70% in the 3 years after their gang injunctions, while the Cambridge Crime Harm Index weight of the seriousness of their total crimes dropped by 61%. Fewer criminal events were attributed to 92% of the individuals in the second 3-year period than in the first, while only 8% increased their detected activity. Taking the four gangs as the unit of analysis, their offences dropped by 74% in the 3 years after the injunctions, while their Crime Harm Index weight dropped by 70%. Victimisation of the gang members in their 3-year post-injunction period dropped by 60% compared to the pre-injunction period. Comparisons between gangs with injunctions and gangs without showed downward crime trends in the injunction gangs that were not observed in the comparisons during the same time periods, but regression to the mean could not be ruled out as an explanation for the findings. Conclusions: The evidence for the effectiveness of gang injunctions in reducing crime harm is stronger than the evidence for most police practices. There is no evidence in this study of these injunctions causing crime to increase. Police agencies may be encouraged to use such powers when available, as long as they track the trends with sufficient care to detect any potential backfire effects