706 research outputs found
Dominant BIN1-related centronuclear myopathy (CNM) revealed by lower limb myalgia and moderate CK elevation
We report a BIN1-related CNM family with unusual clinical phenotype. The proband, a 56-year-old man suffered of lower limbs myalgia since the age of 52. Clinical examination showed short stature, mild symmetric eyelid ptosis without ophthalmoplegia, scapular winging and Achilles tendon retraction. A muscle weakness was not noted. CK levels were up to 350 UI/L. Deltoid muscle biopsy showed nuclear centralization and clustering, deep sarcolemmal invaginations and type 1 fiber hypotrophy. Whole body MRI revealed fatty infiltration of posterior legs compartments, lumbar paraspinal and serratus muscles. Myotonic dystrophy type1 and 2, Pompe disease and MTM1 and DNM2-related CNM were ruled out. By sequencing BIN1, we identified a heterozygous pathogenic mutation [c.107C > A (p.A36E)], and we demonstrate that the mutation strongly impairs the membrane tubulation property of the protein. One affected sister carried the same mutation. Her clinical examination and muscle MRI revealed a similar phenotype. Our findings expand the clinical and genetic spectrum of the autosomal dominant CNM associated with BIN1 mutations
Sub-Doppler laser cooling of potassium atoms
We investigate sub-Doppler laser cooling of bosonic potassium isotopes, whose
small hyperfine splitting has so far prevented cooling below the Doppler
temperature. We find instead that the combination of a dark optical molasses
scheme that naturally arises in this kind of systems and an adiabatic ramping
of the laser parameters allows to reach sub-Doppler temperatures for small
laser detunings. We demonstrate temperatures as low as 25(3)microK and
47(5)microK in high-density samples of the two isotopes 39K and 41K,
respectively. Our findings will find application to other atomic systems.Comment: 7 pages, 9 figure
Expansion dynamics of a dipolar Bose-Einstein condensate
Our recent measurements on the expansion of a chromium dipolar condensate
after release from an optical trapping potential are in good agreement with an
exact solution of the hydrodynamic equations for dipolar Bose gases. We report
here the theoretical method used to interpret the measurement data as well as
more details of the experiment and its analysis. The theory reported here is a
tool for the investigation of different dynamical situations in time-dependent
harmonic traps.Comment: 12 pages. Submitted to PR
Observation of dipole-dipole interaction in a degenerate quantum gas
We have investigated the expansion of a Bose-Einstein condensate (BEC) of
strongly magnetic chromium atoms. The long-range and anisotropic magnetic
dipole-dipole interaction leads to an anisotropic deformation of the expanding
Cr-BEC which depends on the orientation of the atomic dipole moments. Our
measurements are consistent with the theory of dipolar quantum gases and show
that a Cr-BEC is an excellent model system to study dipolar interactions in
such gases.Comment: 4 pages, 2 figure
Atom interferometry gravity-gradiometer for the determination of the Newtonian gravitational constant G
We developed a gravity-gradiometer based on atom interferometry for the
determination of the Newtonian gravitational constant \textit{G}. The
apparatus, combining a Rb fountain, Raman interferometry and a juggling scheme
for fast launch of two atomic clouds, was specifically designed to reduce
possible systematic effects. We present instrument performances and show that
the sensor is able to detect the gravitational field induced by source masses.
A discussion of projected accuracy for \textit{G} measurement using this new
scheme shows that the results of the experiment will be significant to
discriminate between previous inconsistent values.Comment: 9 pages,9 figures, Submitte
Towards an atom interferometric determination of the Newtonian gravitational constant
We report on progress towards an atom interferometric determination of the Newtonian gravitational constant. Free-falling laser-cooled atoms will probe the gravitational potential of nearby source masses. To reduce systematic errors, we will perform double differential measurements between two vertically separated atom clouds and with different source mass positions
Feshbach resonances in ultracold K(39)
We discover several magnetic Feshbach resonances in collisions of ultracold
K(39) atoms, by studying atom losses and molecule formation. Accurate
determination of the magnetic-field resonance locations allows us to optimize a
quantum collision model for potassium isotopes. We employ the model to predict
the magnetic-field dependence of scattering lengths and of near-threshold
molecular levels. Our findings will be useful to plan future experiments on
ultracold potassium atoms and molecules.Comment: 7 pages, 6 figure
Ramsey interferometry with an atom laser
We present results on a free-space atom interferometer operating on the first
order magnetically insensitive |F=1,mF=0> -> |F=2,mF=0> transition of
Bose-condensed 87Rb atoms. A pulsed atom laser is output-coupled from a
Bose-Einstein condensate and propagates through a sequence of two internal
state beam splitters, realized via coherent Raman transitions between the two
interfering states. We observe Ramsey fringes with a visibility close to 100%
and determine the current and the potentially achievable interferometric phase
sensitivity. This system is well suited to testing recent proposals for
generating and detecting squeezed atomic states.Comment: published version, 8 pages, 3 figure
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