8,797 research outputs found
How I treat thrombotic thrombocytopenic purpura and atypical haemolytic uraemic syndrome
Thrombotic thrombocytopenic purpura (TTP) and atypical haemolytic uraemic syndrome (aHUS) are acute, rare life-threatening thrombotic microangiopathies that require rapid diagnosis and treatment. They are defined by microangiopathic haemolytic anaemia and thrombocytopenia, with renal involvement primarily in aHUS and neurological and cardiological sequelae in TTP. Prompt treatment for most cases of both conditions is with plasma exchange initially and monoclonal therapy (rituximab in TTP and eculizumab in aHUS) as the mainstay of therapy. Here we discuss the diagnosis and therapy for both disorders
"Explaining the Impact of Jacques Delors: Conceptualizing and Assessing the Commission Presidency"
This paper analyzes the Presidency of the European Commission as a political leadership position. It does so on three levels. First, it considers the relational nature of leadership, arguing that every leadership position is shaped by its "relationship network"- the relationship of the leader with his constituents, co-actors, and subordinates. Second, it develops a typology of leadership styles, that Commission Presidents might exercise within the limits of the Commission Presidency's highly constraining relationship network. The three main types (neo-functionalist, federalist and intergovernmentalist) integrate integration theory literature with existing knowledge of the activities of Commission Presidents. Third, these ideas, and a personality-assessment-at-a-distance technique, are employed in a case-study of Jacques Delors. The study shows that Delor's leadership cannot be understood in simple Euro-federalist terms. It also shows the ability of the concepts and methods used to advance comparative study of the Commission Presidency
Fluorescence interferometry
We describe an interferometer based on fluorescent emission of radiation of
two qubits in quasi-one-dimensional modes. Such a system can be readily
realized with dipole emitters near conducting surface-plasmonic nanowires or
with superconducting qubits coupled to coplanar waveguide transmission lines.Comment: 7 pages, 2 figure
Coherent control of atomic tunneling
We study the tunneling of a two-level atom in a double well potential while
the atom is coupled to a single electromagnetic field mode of a cavity. The
coupling between internal and external degrees of freedom, due to the
mechanical effect on the atom from photon emission into the cavity mode, can
dramatically change the tunneling behavior. We predict that in general the
tunneling process becomes quasiperiodic. In a certain regime of parameters a
collapse and revival of the tunneling occurs. Accessing the internal degrees of
freedom of the atom with a laser allows to coherently manipulate the atom
position, and in particular to prepare the atom in one of the two wells. The
effects described should be observable with atoms in an optical double well
trap.Comment: 6 pages revtex, 4 figures, extended version including numerical
results taking into account higher vibrationnal level
Generation of two-mode field squeezing through selective dynamics in cavity QED
We propose a scheme for the generation of a two-mode field squeezed state in
cavity QED. It is based on two-channel Raman excitations of a beam of
three-level atoms with random arrival times by two classical fields and two
high-Q resonator modes. It is shown that by suitably choosing the intensities
and detunings of fields the dynamical processes can be selective and two-mode
squeezing between the cavity modes can be generated at steady state. This
proposal does not need the preparation of the initial states of atoms and
cavity modes, and is robust against atomic spontaneous decay.Comment: 4 pages,2 figure
Quantum limit of optical magnetometry in the presence of ac-Stark shifts
We analyze systematic (classical) and fundamental (quantum) limitations of
the sensitivity of optical magnetometers resulting from ac-Stark shifts. We
show that in contrast to absorption-based techniques, the signal reduction
associated with classical broadening can be compensated in magnetometers based
on phase measurements using electromagnetically induced transparency (EIT).
However due to ac-Stark associated quantum noise the signal-to-noise ratio of
EIT-based magnetometers attains a maximum value at a certain laser intensity.
This value is independent on the quantum statistics of the light and defines a
standard quantum limit of sensitivity. We demonstrate that an EIT-based optical
magnetometer in Faraday configuration is the best candidate to achieve the
highest sensitivity of magnetic field detection and give a detailed analysis of
such a device.Comment: 11 pages, 4 figure
From EIT photon correlations to Raman anti-correlations in coherently prepared Rb vapor
We have experimentally observed switching between photon-photon correlations
(bunching) and anti-correlations (anti-bunching) between two orthogonally
polarized laser beams in an EIT configuration in Rb vapor. The bunching and
anti-bunching sswitching occurs at a specific magnetic field strength.Comment: 4 pages and 3 figure
Nonlinear coupling of nano mechanical resonators to Josephson quantum circuits
We propose a technique to couple the position operator of a nano mechanical
resonator to a SQUID device by modulating its magnetic flux bias. By tuning the
magnetic field properly, either linear or quadratic couplings can be realized,
with a discretely adjustable coupling strength. This provides a way to realize
coherent nonlinear effects in a nano mechanical resonator by coupling it to a
Josephson quantum circuit. As an example, we show how squeezing of the nano
mechanical resonator state can be realized with this technique. We also propose
a simple method to measure the uncertainty in the position of the nano
mechanical resonator without quantum state tomography
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