1,008 research outputs found
Direct Josephson coupling between superconducting flux qubits
We have demonstrated strong antiferromagnetic coupling between two
three-junction flux qubits based on a shared Josephson junction, and therefore
not limited by the small inductances of the qubit loops. The coupling sign and
magnitude were measured by coupling the system to a high-quality
superconducting tank circuit. Design modifications allowing to continuously
tune the coupling strength and/or make the coupling ferromagnetic are
discussed.Comment: REVTeX 4, 4 pages, 5 figures; v2: completely rewritten, added
finite-temperature results and proposals for ferromagnetic galvanic couplin
A new find of Megalotragus priscus (Alcelaphini, Bovidae) from the central Karoo, South Africa
Main articleWe document the occurrence of the Florisian, or late Quaternary, form of the giant alcelaphine,
Megalotragus priscus, from dongas on the Ongers River, near Britstown in the central Karoo. This
is significant as it confirms the occurrence of the species in the Karoo and it suggests significantly
wetter environments and productive grasslands in the central Karoo in pre-Holocene times. The
present-day Karoo environment did not maintain populations of large ruminant grazers similar to
M. priscus, and other specialized Florisian grazers, prior to the advent of agriculture and pasture
management. Aridification in recent times is the likely cause of changes in grassland quality and
the local dissappearance of these animals, if not their extinction.Non
The prognostic value of the hamstring outcome score to predict the risk of hamstring injuries
OBJECTIVES: Hamstring injuries are common among soccer players. The hamstring outcome score (HaOS) might be useful to identify amateur players at risk of hamstring injury. Therefore the aims of this study were: To determine the association between the HaOS and prior and new hamstring injuries in amateur soccer players, and to determine the prognostic value of the HaOS for identifying players with or without previous hamstring injuries at risk of future injury. DESIGN: Cohort study. METHODS: HaOS scores and information about previous injuries were collected at baseline and new injuries were prospectively registered during a cluster-randomized controlled trial involving 400 amateur soccer players. Analysis of variance and t-tests were used to determine the association between the HaOS and previous and new hamstring injury, respectively. Logistic regression analysis indicated the prognostic value of the HaOS for predicting new hamstring injuries. RESULTS: Analysis of data of 356 players indicated that lower HaOS scores were associated with more previous hamstring injuries (F=17.4; p=0.000) and that players with lower HaOS scores sustained more new hamstring injuries (T=3.59, df=67.23, p=0.001). With a conventional HaOS score cut-off of 80%, logistic regression models yielded a probability of hamstring injuries of 11%, 18%, and 28% for players with 0,1, or 2 hamstring injuries in the previous season, respectively. CONCLUSIONS: The HaOS is associated with previous and future hamstring injury and might be a useful tool to provide players with insight into their risk of sustaining a new hamstring injury risk when used in combination with previous injuries
PENGONTROL TEMPERATUR RUANGAN BERBASIS MICROCONTROLLER AT89S51
Dalam ruangan yang tertutup (close-loop system), suhu adalah salah satu faktor yang berpengaruh terhadap lingkungannya
Metastable Voltage States of Coupled Josephson Junctions
We investigate a chain of capacitively coupled Josephson junctions in the
regime where the charging energy dominates over the Josephson coupling,
exploiting the analogy between this system and a multi-dimensional crystal. We
find that the current-voltage characteristic of the current-driven chain has a
staircase shape, beginning with an (insulating) non-zero voltage plateau at
small currents. This behavior differs qualitatively from that of a single
junction, which should show Bloch oscillations with vanishing dc voltage. The
simplest system where this effect can be observed consists of three grains
connected by two junctions. The theory explains the results of recent
experiments on Josephson junction arrays.Comment: 5 pages, 4 figures include
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
Effective spinless fermions in the strong coupling Kondo model
Starting from the two-orbital Kondo-lattice model with classical t_2g spins,
an effective spinless fermion model is derived for strong Hund coupling J_H
with a projection technique. The model is studied by Monte Carlo simulations
and analytically using a uniform hopping approximation. The results for the
spinless fermion model are in remarkable agreement with those of the original
Kondo-lattice model, independent of the carrier concentration, and even for
moderate Hund coupling J_H. Phase separation, the phase diagram in uniform
hopping approximation, as well as spectral properties including the formation
of a pseudo-gap are discussed for both the Kondo-lattice and the effective
spinless fermion model in one and three dimensions.Comment: Revtex4, 10 pages, 15 figures, typos correcte
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