2,975 research outputs found
Excitation and control of large amplitude standing magnetization waves
A robust approach to excitation and control of large amplitude standing
magnetization waves in an easy axis ferromagnetic by starting from a ground
state and passage through resonances with chirped frequency microwave or spin
torque drives is proposed. The formation of these waves involves two stages,
where in the first stage, a spatially uniform, precessing magnetization is
created via passage through a resonance followed by a self-phase-locking
(autoresonance) with a constant amplitude drive. In the second stage, the
passage trough an additional resonance with a spatial modulation of the driving
amplitude yields transformation of the uniform solution into a doubly
phase-locked standing wave, whose amplitude is controlled by the variation of
the driving frequency. The stability of this excitation process is analyzed
both numerically and via Whitham's averaged variational principle
Autoresonant excitation of Bose-Einstein condensates
Controlling the state of a Bose-Einstein condensate driven by a chirped
frequency perturbation in a one-dimensional anharmonic trapping potential is
discussed. By identifying four characteristic time scales in this
chirped-driven problem, three dimensionless parameters are defined
describing the driving strength, the anharmonicity of the trapping potential,
and the strength of the particles interaction, respectively. As the driving
frequency passes the linear resonance in the problem, and depending on the
location in the parameter space, the system may exhibit two very
different evolutions, i.e. the quantum energy ladder climbing (LC) and the
classical autoresonance (AR). These regimes are analysed both in theory and
simulations with the emphasis on the effect of the interaction parameter
. In particular, the transition thresholds on the driving parameter
and their width in in both the AR and LC regimes are discussed.
Different driving protocols are also illustrated, showing efficient control of
excitation and de-excitation of the condensate
Rashi, \u3cem\u3eThe \u3c/em\u3e Jewish Exegete
Until modern times virtually every Jewish child imbibed the teachings, the narrative, and law of the Pentateuch with the assistance of Rashi\u27s commentary, or, as the Yiddish expression has it, Humash mit Rashi. Rashi\u27s Bible and Talmud commentaries are still unmatched for conciseness, clarity, and the sure touch of the born educator. Though of medieval French provenance, Rashi\u27s expositions were adopted by Jews everywhere, Ashkenazic, Sephardic, and Oriental, for nearly a thousand years. Nor was his influence restricted to Jews. Within a century after his death, his commentary was taken up by a learned Franciscan monk whose discourses were to lend shape to Martin Luther\u27s rendition of the Hebrew Bible into German, thus indirectly affecting the King James Version
Phase-locking transition in a chirped superconducting Josephson resonator
By coupling a harmonic oscillator to a quantum system it is possible to
perform a dispersive measurement that is quantum non-demolition (QND), with
minimal backaction. A non-linear oscillator has the advantage of measurement
gain, but what is the backaction? Experiments on superconducting quantum bits
(qubits) coupled to a non-linear Josephson oscillator have thus far utilized
the switching of the oscillator near a dynamical bifurcation for sensitivity,
and have demonstrated partial QND measurement. The detailed backaction
associated with the switching process is complex, and may ultimately limit the
degree to which such a measurement can be QND. Here we demonstrate a new
dynamical effect in Josephson oscillators by which the bifurcation can be
accessed without switching. When energized with a frequency chirped drive with
an amplitude close to a sharp, phase-locking threshold, the oscillator evolves
smoothly in one of two diverging trajectories - a pointer for the state of a
qubit. The observed critical behavior agrees well with theory and suggests a
new modality for quantum state measurement.Comment: 5 pages, 4 figure
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Access to healthcare for people seeking and refused asylum in Great Britain: a review of evidence
This research report is a review of evidence looking at the barriers people seeking or refused asylum face in trying to access healthcare services in the UK, and what may help them to do so more easily.
This report, and the partner report on lived experiences (https://www.equalityhumanrights.com/en/publication-download/lived-experiences-access-healthcare-people-seeking-and-refused-asylum), will be of interest to people who play an important role in delivering healthcare and related support services to people seeking or refused asylum.
We have also made recommendations for what changes are needed (https://www.equalityhumanrights.com/en/publication-download/making-sure-people-seeking-and-refused-asylum-can-access-healthcare-what-needs) to make sure that people seeking and refused asylum have full enjoyment of their right to health.
This review was carried out by Imperial College London, with primary data provided by Doctors of the World UK
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