2,839 research outputs found
The critical properties of the agent-based model with environmental-economic interactions
The steady-state and nonequilibrium properties of the model of
environmental-economic interactions are studied. The interacting heterogeneous
agents are simulated on the platform of the emission dynamics of cellular
automaton. The model possess the discontinuous transition between the safe and
catastrophic ecology. Right at the critical line, the broad-scale power-law
distributions of emission rates have been identified. Their relationship to
Zipf's law and models of self-organized criticality is discussed.Comment: 12 pages, 6 figures, published in Physica
Ischemia and reperfusion injury in kidney transplantation : relevant mechanisms in injury and repair
Ischemia and reperfusion injury (IRI) is a complex pathophysiological phenomenon, inevitable in kidney transplantation and one of the most important mechanisms for non- or delayed function immediately after transplantation. Long term, it is associated with acute rejection and chronic graft dysfunction due to interstitial fibrosis and tubular atrophy. Recently, more insight has been gained in the underlying molecular pathways and signalling cascades involved, which opens the door to new therapeutic opportunities aiming to reduce IRI and improve graft survival. This review systemically discusses the specific molecular pathways involved in the pathophysiology of IRI and highlights new therapeutic strategies targeting these pathways
Realization of a classical counterpart of a scalable design for adiabatic quantum computation
We implement a classical counterpart of a scalable design for adiabatic
quantum computation. The key element of this design is a coupler providing
controllable coupling between two bistable elements (in our case
superconducting rings with a single Josephson junction playing the role of a
classical counterpart of superconducting flux qubits) The coupler is also a
superconducting ring with a single Josephson junction that operates in the
non-hysteretic mode. The flux coupling between two bistable rings can be
controlled by changing the magnetic flux through the coupler. Thereby, the
coupling can be tuned from ferromagnetic trough zero to to anti-ferromagnetic.Comment: 3 pages, 3 figures v2: extended discussion experimental result
Measurement of the ground-state flux diagram of three coupled qubits as a first step towards the demonstration of adiabatic quantum computation
The ground state susceptibility of a system consisting of three flux-qubits
was measured in the complete three dimensional flux space around the common
degeneracy point of the qubits. The system's Hamiltonian could be completely
reconstructed from measurements made far away from the common degeneracy point.
The subsequent measurements made around this point show complete agreement with
the theoretical predictions which follow from this Hamiltonian. The ground
state anti-crossings of the system could be read-out directly from these
measurements. This allows one to determine the ground-state flux diagram, which
provides the solution for the non-polynomial optimization problem MAXCUT
encoded in the Hamiltonian of the three-flux-qubit system. Our results show
that adiabatic quantum computation can be demonstrated with this system
provided that the energy gap and/or the speed of the read-out is increased.Comment: accepted for publication by Europhysics Letter
The relationships between internal and external threat and right-wing attitudes: A three-wave longitudinal study
The interplay between threat and right-wing attitudes has received much research attention, but its longitudinal relationship has hardly been investigated. In this study, we investigated the longitudinal relationships between internal and external threat and right-wing attitudes using a cross-lagged design at three different time points in a large nationally representative sample (N = 800). We found evidence for bidirectional relationships. Higher levels of external threat were related to higher levels of Right-Wing Authoritarianism and to both the egalitarianism and dominance dimensions of Social Dominance Orientation at a later point in time. Conversely, higher levels of RWA were also related to increased perception of external threat later in time. Internal threat did not yield significant direct or indirect longitudinal relationships with right-wing attitudes. Theoretical and practical implications of these longitudinal effects are discussed
Four-qubit device with mixed couplings
We present the first experimental results on a device with more than two
superconducting qubits. The circuit consists of four three-junction flux
qubits, with simultaneous ferro- and antiferromagnetic coupling implemented
using shared Josephson junctions. Its response, which is dominated by the
ground state, is characterized using low-frequency impedance measurement with a
superconducting tank circuit coupled to the qubits. The results are found to be
in excellent agreement with the quantum-mechanical predictions.Comment: REVTeX 4, 5pp., 7 EPS figure files. N.B.: "Alec" is my first, and
"Maassen van den Brink" my family name. v2: final published version, with
changed title, different sample micrograph, and several clarification
Coupling Superconducting Qubits via a Cavity Bus
Superconducting circuits are promising candidates for constructing quantum
bits (qubits) in a quantum computer; single-qubit operations are now routine,
and several examples of two qubit interactions and gates having been
demonstrated. These experiments show that two nearby qubits can be readily
coupled with local interactions. Performing gates between an arbitrary pair of
distant qubits is highly desirable for any quantum computer architecture, but
has not yet been demonstrated. An efficient way to achieve this goal is to
couple the qubits to a quantum bus, which distributes quantum information among
the qubits. Here we show the implementation of such a quantum bus, using
microwave photons confined in a transmission line cavity, to couple two
superconducting qubits on opposite sides of a chip. The interaction is mediated
by the exchange of virtual rather than real photons, avoiding cavity induced
loss. Using fast control of the qubits to switch the coupling effectively on
and off, we demonstrate coherent transfer of quantum states between the qubits.
The cavity is also used to perform multiplexed control and measurement of the
qubit states. This approach can be expanded to more than two qubits, and is an
attractive architecture for quantum information processing on a chip.Comment: 6 pages, 4 figures, to be published in Natur
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