88 research outputs found
The EMU Stability and Growth Pact: Is it dead? If so, does it matter?
IN DECEMBER 2004, the new Barroso Commission brought the saga of the French and German infringements of the Stability and Growth Pact to a close by lifting the "excessive deficit" procedure launched in 2003. That same month, the Commission launched infringement proceedings against Greece that has been providing inaccurate public deficit statistics since the creation of the Pact in 1997. The new head of the Commission also declared that there would be no major overhaul of the Pact. In the November 2003 crisis, when the Council suspended the implementation of the Pact at a time France and Germany overshot its deficit ceiling, most observers called the Pact dead and many rejoiced since the Stability and Growth Pact had come under heavy criticism for some time. A year after, we asked four leading scholars that have studied monetary integration: have news of the death of the Stability and Growth pact been grossly exaggerated? Should it be resuscitated? Why or why not? Amy Verdun and Nicolas Jabko argue that the Pact will survive for lack of an alternative able to gather the support of a large bipartisan cross-national coalition. Henrik Enderlein then argues that the pact should not be fixed but broken. Finally, Andrew Martin explains why the real problem does not so much lie with the Pact per se, but instead with the philosophy behind the EMU policy mix (restrictive fiscal and monetary policies). It creates vicious circles: By keeping economic growth too low the European central bank retarded the expansion of public revenue, making it more difficult to meet the Pact requirements
Single ions trapped in a one-dimensional optical lattice
We report on three-dimensional optical trapping of single ions in an optical
lattice formed by two counter-propagating laser beams. We characterize the
trapping parameters of the standing wave using the ion as a sensor stored in a
hybrid trap consisting of a radio-frequency (rf), a dc, and the optical
potential. When loading ions directly from the rf into the standing-wave trap,
we observe a dominant heating rate. Monte Carlo simulations confirm rf-induced
parametric excitations within the deep optical lattice as the main source. We
demonstrate a way around this effect by an alternative transfer protocol which
involves an intermediate step of optical confinement in a single-beam trap
avoiding the temporal overlap of the standing wave and the rf field.
Implications arise for hybrid (rf/optical) and pure optical traps as platforms
for ultra-cold chemistry experiments exploring atom--ion collisions or quantum
simulation experiments with ions, or combinations of ions and atoms.Comment: 5 pages, 4 figure
Influence of static electric fields on an optical ion trap
We recently reported on a proof-of-principle experiment demonstrating optical
trapping of an ion in a single-beam dipole trap superimposed by a static
electric potential [Nat. Photonics 4, 772--775 (2010)]. Here, we first discuss
the experimental procedures focussing on the influence and consequences of the
static electric potential. These potentials can easily prevent successful
optical trapping, if their configuration is not chosen carefully. Afterwards,
we analyse the dipole trap experiments with different analytic models, in which
different approximations are applied. According to these models the
experimental results agree with recoil heating as the relevant heating effect.
In addition, a Monte-Carlo simulation has been developed to refine the
analysis. It reveals a large impact of the static electric potential on the
dipole trap experiments in general. While it supports the results of the
analytic models for the parameters used in the experiments, the analytic models
cease their validity for significantly different parameters. Finally, we
propose technical improvements for future realizations of experiments with
optically trapped ions.Comment: 16 pages, 16 figure
Single NanoParticle Photothermal Tracking (SNaPT) of 5 nm gold beads in live cells
Tracking individual nano-objets in live cells during arbitrary long times is
an ubiquitous need in modern biology. We present here a method for tracking
individual 5 nm gold nanoparticles on live cells. It relies on the photothermal
effect and the detection of the Laser Induced Scattering around a NanoAbsorber
(LISNA). The key point for recording trajectories at video rate is the use of a
triangulation procedure. The effectiveness of the method is tested against
Single fluorescent Molecule Tracking in live COS7 cells on subsecond time
scales. We further demonstrate recordings for several minutes of AMPA receptors
trajectories on the plasma membrane of live neurons. SNaPT has the unique
potential to record arbitrary long trajectory of membrane proteins using
non-fluorescent nanometer sized labels
Recent Developments in Fluorescence Correlation Spectroscopy for Diffusion Measurements in Planar Lipid Membranes
Fluorescence correlation spectroscopy (FCS) is a single molecule technique used mainly for determination of mobility and local concentration of molecules. This review describes the specific problems of FCS in planar systems and reviews the state of the art experimental approaches such as 2-focus, Z-scan or scanning FCS, which overcome most of the artefacts and limitations of standard FCS. We focus on diffusion measurements of lipids and proteins in planar lipid membranes and review the contributions of FCS to elucidating membrane dynamics and the factors influencing it, such as membrane composition, ionic strength, presence of membrane proteins or frictional coupling with solid support
Recent Applications of Fluorescence Recovery after Photobleaching (FRAP) to Membrane Bio-Macromolecules
This review examines some recent applications of fluorescence recovery after photobleaching (FRAP) to biopolymers, while mainly focusing on membrane protein studies. Initially, we discuss the lateral diffusion of membrane proteins, as measured by FRAP. Then, we talk about the use of FRAP to probe interactions between membrane proteins by obtaining fundamental information such as geometry and stoichiometry of the interacting complex. Afterwards, we discuss some applications of FRAP at the cellular level as well as the level of organisms. We conclude by comparing diffusion coefficients obtained by FRAP and several other alternative methods
Demographic, clinical and antibody characteristics of patients with digital ulcers in systemic sclerosis: data from the DUO Registry
OBJECTIVES: The Digital Ulcers Outcome (DUO) Registry was designed to describe the clinical and antibody characteristics, disease course and outcomes of patients with digital ulcers associated with systemic sclerosis (SSc).
METHODS: The DUO Registry is a European, prospective, multicentre, observational, registry of SSc patients with ongoing digital ulcer disease, irrespective of treatment regimen. Data collected included demographics, SSc duration, SSc subset, internal organ manifestations, autoantibodies, previous and ongoing interventions and complications related to digital ulcers.
RESULTS: Up to 19 November 2010 a total of 2439 patients had enrolled into the registry. Most were classified as either limited cutaneous SSc (lcSSc; 52.2%) or diffuse cutaneous SSc (dcSSc; 36.9%). Digital ulcers developed earlier in patients with dcSSc compared with lcSSc. Almost all patients (95.7%) tested positive for antinuclear antibodies, 45.2% for anti-scleroderma-70 and 43.6% for anticentromere antibodies (ACA). The first digital ulcer in the anti-scleroderma-70-positive patient cohort occurred approximately 5 years earlier than the ACA-positive patient group.
CONCLUSIONS: This study provides data from a large cohort of SSc patients with a history of digital ulcers. The early occurrence and high frequency of digital ulcer complications are especially seen in patients with dcSSc and/or anti-scleroderma-70 antibodies
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