Direct Observation of Large Amplitude Spin Excitations Localized in a Spin-Transfer Nanocontact

We report the direct observation of large amplitude spin-excitations localized in a spin-transfer nanocontact using scanning transmission x-ray microscopy. Experiments were conducted using a nanocontact to an ultrathin ferromagnetic multilayer with perpendicular magnetic anisotropy. Element resolved x-ray magnetic circular dichroism images show an abrupt onset of spin excitations at a threshold current that are localized beneath the nanocontact, with average spin precession cone angles of 25{\deg} at the contact center. The results strongly suggest that we have observed a localized magnetic soliton.Comment: 5 pages, 3 figure

The JPL telerobotic Manipulator Control and Mechanization (MCM) subsystem

The Manipulator Control and Mechanization (MCM) subsystem of the telerobot system provides the real-time control of the robot manipulators in autonomous and teleoperated modes and real time input/output for a variety of sensors and actuators. Substantial hardware and software are included in this subsystem which interfaces in the hierarchy of the telerobot system with the other subsystems. The other subsystems are: run time control, task planning and reasoning, sensing and perception, and operator control subsystem. The architecture of the MCM subsystem, its capabilities, and details of various hardware and software elements are described. Important improvements in the MCM subsystem over the first version are: dual arm coordinated trajectory generation and control, addition of integrated teleoperation, shared control capability, replacement of the ultimate controllers with motor controllers, and substantial increase in real time processing capability

Telerobot control system

This invention relates to an operator interface for controlling a telerobot to perform tasks in a poorly modeled environment and/or within unplanned scenarios. The telerobot control system includes a remote robot manipulator linked to an operator interface. The operator interface includes a setup terminal, simulation terminal, and execution terminal for the control of the graphics simulator and local robot actuator as well as the remote robot actuator. These terminals may be combined in a single terminal. Complex tasks are developed from sequential combinations of parameterized task primitives and recorded teleoperations, and are tested by execution on a graphics simulator and/or local robot actuator, together with adjustable time delays. The novel features of this invention include the shared and supervisory control of the remote robot manipulator via operator interface by pretested complex tasks sequences based on sequences of parameterized task primitives combined with further teleoperation and run-time binding of parameters based on task context

Monte Carlo study of fermionic trions in a square lattice with harmonic confinement

We investigate the strong-coupling limit of a three-component Fermi mixture in an optical lattice with attractive interactions. In this limit bound states (trions) of the three components are formed. We derive an effective Hamiltonian for these composite fermions and show that it is asymptotically equivalent to an antiferromagnetic Ising model. By using Monte-Carlo simulations, we investigate the spatial arrangement of the trions and the formation of a trionic density wave (CDW), both in a homogeneous lattice and in the presence of an additional harmonic confinement. Depending on the strength of the confinement and on the temperature, we found several scenarios for the trionic distribution, including coexistence of disordered trions with CDW and band insulator phases. Our results show that, due to a proximity effect, staggered density modulations are induced in regions of the trap where they would not otherwise be present according to the local density approximation.Comment: 10 pages, 8 figure

X-Ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu

We have used a MHz lock-in x-ray spectro-microscopy technique to directly detect changes of magnetic moments in Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x-rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of $3\times 10^{-5}$ $\mu_\mathrm{B}$ on Cu atoms within the bulk of the 28 nm thick Cu film due to spin-accumulation. The moment value is compared to predictions by Mott's two current model. We also observe that the hybridization induced existing magnetic moments on Cu interface atoms are transiently increased by about 10% or $4\times 10^{-3}$ $\mu_\mathrm{B}$. This reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow

Planning is the key to success - but for whom and how? : action-state orientation and specificity as moderators of implementation intention effects on goal achievement

Abstract The present research was conducted in order to identify moderators of implementation intention effects, a flexibly applicable planning strategy. Individual differences and the phrasing of implementation intentions were scrutinized as potential moderators. In Part I we demonstrate in three studies that individual differences in action-state orientation moderate implementation intention effects. Individual differences in action-state orientation reflect relevant differences in self-regulatory competencies. Because action-state orientation makes different predictions about successful performance for different self-regulatory problems, we examined different self-regulatory challenges. As expected, the moderating effect of action-state orientation depended on the respective self-regulatory problem. State oriented individuals needed implementation intentions to initiate goal-directed behavior timely. Action oriented individuals increased their performance in complex decision making with implementation intentions. State oriented individuals however were handicapped in complex decision making when instructed to use implementation intentions. In Part II we scrutinize whether the specificity of implementation intentions moderates their effectiveness. Although we varied the experimental design repeatedly, neither the expected moderation nor implementation intention effects were found in any of the reaction time experiments. We discuss possible reasons for the lack of effects and propose further enhancements for future studies. Zusammenfassung In der vorliegenden Doktorarbeit wurden potentielle Moderatorvariablen des Implementierungsintentionseffekts untersucht. Implementierungsintentionen gelten als flexibel anwendbare Planungsstrategie, die die Erreichung eines Ziels fördert. Es wurden zum einen personenspezifische Variablen und zum anderen verschiedene Möglichkeiten, Implementierungsintentionen zu formulieren, als mögliche Moderatorvariablen betrachtet. Im ersten Teil wurde in drei Studien gezeigt, dass die personenspezifische Variable Handlungs-Lageorientierung, welche auf Unterschiede in selbstregulatorischen Kompetenzen schliessen lässt, Implementierungsintentionseffekte moderiert. Hierfür wurden verschiedene selbstregulatorisch herausfordernde Situationen untersucht: Zunächst wurde die Initiierung zielgerichteten Verhaltens, dann das Lösen von komplexen Problemen betrachtet. In den präsentierten Studien benötigten lageorientierte Personen Implementierungsintentionen, um zielgerichtetes Verhalten pünktlich zu initiieren, beim Lösen komplexer Probleme wurden sie jedoch durch Implementierungsintentionen behindert, während handlungsorientierte Personen beim Lösen komplexer Probleme von Implementierungsintentionen profitierten. Im zweiten Teil der Arbeit wurde untersucht, ob die Spezifität der Implementierungsintentionen deren Wirksamkeit beeinflusst. Obwohl das experimentelle Design in mehreren Reaktionszeitstudien variiert wurde, konnten weder Implementierungseffekte noch die erwartete moderierende Wirkung der Spezifität gezeigt werden. Es werden mögliche Ursachen für die ausbleibenden Effekte diskutiert

Apprentice pay in Britain, Germany and Switzerland: Institutions, market forces and market power

This is the accepted version of the original publication in the European Journal of Industrial Relations, which is available online at http://ejd.sagepub.com/content/19/3/201.The pay of metalworking apprentices is high in Britain, middling in Germany and low in Switzerland. We analyse these differences using fieldwork evidence and survey data, drawing on both economic and institutionalist theories. Several institutional attributes influence apprentice pay, partly by affecting supply and demand in markets for training places. Institutional support for apprenticeship training appears to involve important complementarities in both Germany and Switzerland, in contrast to Britain’s less coherent and more market-driven approach.We thank the Hans-Böckler-Stiftung, Anglo-German Foundation, SKOPE (Oxford), the Swiss federal government (OPET/SERI) and WZB (Berlin) for financial support

Understanding and optimising the packing density of perylene bisimide layers on CVD-grown graphene

The non-covalent functionalisation of graphene is an attractive strategy to alter the surface chemistry of graphene without damaging its superior electrical and mechanical properties. Using the facile method of aqueous-phase functionalisation on large-scale CVD-grown graphene, we investigated the formation of different packing densities in self-assembled monolayers (SAMs) of perylene bisimide derivatives and related this to the amount of substrate contamination. We were able to directly observe wet-chemically deposited SAMs in scanning tunnelling microscopy (STM) on transferred CVD graphene and revealed that the densely packed perylene ad-layers adsorb with the conjugated {\pi}-system of the core perpendicular to the graphene substrate. This elucidation of the non-covalent functionalisation of graphene has major implications on controlling its surface chemistry and opens new pathways for adaptable functionalisation in ambient conditions and on the large scale.Comment: 27 pages (including SI), 10 figure

Composable security of delegated quantum computation

Delegating difficult computations to remote large computation facilities, with appropriate security guarantees, is a possible solution for the ever-growing needs of personal computing power. For delegated computation protocols to be usable in a larger context---or simply to securely run two protocols in parallel---the security definitions need to be composable. Here, we define composable security for delegated quantum computation. We distinguish between protocols which provide only blindness---the computation is hidden from the server---and those that are also verifiable---the client can check that it has received the correct result. We show that the composable security definition capturing both these notions can be reduced to a combination of several distinct "trace-distance-type" criteria---which are, individually, non-composable security definitions. Additionally, we study the security of some known delegated quantum computation protocols, including Broadbent, Fitzsimons and Kashefi's Universal Blind Quantum Computation protocol. Even though these protocols were originally proposed with insufficient security criteria, they turn out to still be secure given the stronger composable definitions.Comment: 37+9 pages, 13 figures. v3: minor changes, new references. v2: extended the reduction between composable and local security to include entangled inputs, substantially rewritten the introduction to the Abstract Cryptography (AC) framewor