898 research outputs found
Precision measurement of gravity with cold atoms in an optical lattice and comparison with a classical gravimeter
We report on a high precision measurement of gravitational acceleration using
ultracold strontium atoms trapped in a vertical optical lattice. Using
amplitude modulation of the lattice intensity, an uncertainty was reached by measuring at the 5 harmonic of the Bloch
oscillation frequency. After a careful analysis of systematic effects, the
value obtained with this microscopic quantum system is consistent with the one
we measured with a classical absolute gravimeter at the same location. This
result is of relevance for the recent interpretation of related experiments as
tests of gravitational redshift and opens the way to new tests of gravity at
micrometer scale.Comment: 4 pages, 4 figure
Coherent control of quantum transport: modulation-enhanced phase detection and band spectroscopy
Amplitude modulation of a tilted optical lattice can be used to steer the
quantum transport of matter wave packets in a very flexible way. This allows
the experimental study of the phase sensitivity in a multimode interferometer
based on delocalization-enhanced Bloch oscillations and to probe the band
structure modified by a constant force.Comment: 8 pages, 3 figures, Submitted to EPJ Special Topics for the special
issue on "Novel Quantum Phases and Mesoscopic Physics in Quantum Gases
Test of Einstein Equivalence Principle for 0-spin and half-integer-spin atoms: Search for spin-gravity coupling effects
We report on a conceptually new test of the equivalence principle performed
by measuring the acceleration in Earth's gravity field of two isotopes of
strontium atoms, namely, the bosonic Sr isotope which has no spin vs the
fermionic Sr isotope which has a half-integer spin. The effect of
gravity upon the two atomic species has been probed by means of a precision
differential measurement of the Bloch frequency for the two atomic matter waves
in a vertical optical lattice. We obtain the values for the E\"otv\"os parameter and
for the coupling between nuclear spin and gravity.
This is the first reported experimental test of the equivalence principle for
bosonic and fermionic particles and opens a new way to the search for the
predicted spin-gravity coupling effects.Comment: 5 pages, 4 figures. New spin-gravtity coupling analysis on the data
added to the manuscrip
Precise study of asymptotic physics with subradiant ultracold molecules
Weakly bound molecules have physical properties without atomic analogues,
even as the bond length approaches dissociation. In particular, the internal
symmetries of homonuclear diatomic molecules result in formation of two-body
superradiant and subradiant excited states. While superradiance has been
demonstrated in a variety of systems, subradiance is more elusive due to the
inherently weak interaction with the environment. Here we characterize the
properties of deeply subradiant molecular states with intrinsic quality factors
exceeding via precise optical spectroscopy with the longest
molecule-light coherent interaction times to date. We find that two competing
effects limit the lifetimes of the subradiant molecules, with different
asymptotic behaviors. The first is radiative decay via weak magnetic-dipole and
electric-quadrupole interactions. We prove that its rate increases
quadratically with the bond length, confirming quantum mechanical predictions.
The second is nonradiative decay through weak gyroscopic predissociation, with
a rate proportional to the vibrational mode spacing and sensitive to
short-range physics. This work bridges the gap between atomic and molecular
metrology based on lattice-clock techniques, yielding new understanding of
long-range interatomic interactions and placing ultracold molecules at the
forefront of precision measurements.Comment: 12 pages, 6 figure
High-precision spectroscopy of ultracold molecules in an optical lattice
The study of ultracold molecules tightly trapped in an optical lattice can
expand the frontier of precision measurement and spectroscopy, and provide a
deeper insight into molecular and fundamental physics. Here we create, probe,
and image microkelvin Sr molecules in a lattice, and demonstrate
precise measurements of molecular parameters as well as coherent control of
molecular quantum states using optical fields. We discuss the sensitivity of
the system to dimensional effects, a new bound-to-continuum spectroscopy
technique for highly accurate binding energy measurements, and prospects for
new physics with this rich experimental system.Comment: 12 pages, 4 figure
Humerus shaft fracture complicated by radial nerve palsy: Is surgical exploration necessary?
Fractures of the humerus shaft often are complicated by radial nerve palsy. Controversy still exists in the treatment that includes clinical observation and eventually late surgical exploration or early surgical exploration. Algorithms have been proposed to provide recommendations with regard to management of the injuries. However, advantages and disadvantages are associated with each of these algorithms. The aim of this study was to analyze the indications of each treatment options and facilitate the surgeon in choosing the conduct for each lesion, proposing our own algorithm
BaH molecular spectroscopy with relevance to laser cooling
We describe a simple experimental apparatus for laser ablation of barium
monohydride (BaH) molecules and the study of their rovibrational spectra that
are relevant to direct laser cooling. We present a detailed analysis of the
properties of ablation plumes that can improve the understanding of surface
ablation and deposition technologies. A range of absorption spectroscopy and
collisional thermalization regimes has been studied. We directly measured the
Franck-Condon factor of the
transition.
Prospects for production of a high luminosity cryogenic BaH beam are outlined.
This molecule is a promising candidate for laser cooling and ultracold
fragmentation, both of which are precursors to novel experiments in many-body
physics and precision measurement.Comment: 11 pages, 10 figure
Technology applications in shoulder replacement
The advancement of technologies in orthopaedic surgery should provide the surgeon with precise and trustworthy support for pre-operative planning, intra-operative guidance and post-operative follow-up. The request for greater accuracy, predictable results and fewer complications, is the engine of digital evolution in pre-operative planning and computer-assisted surgery (CAS). It is an evolution rather than a revolution, and in the last few years these developments have begun to involve shoulder replacement surgery, too
Targeted Gene Mutations in the Forest Pathogen Dothistroma septosporum Using CRISPR/Cas9.
Dothistroma needle blight, caused by Dothistroma septosporum, has increased in incidence and severity over the last few decades and is now one of the most important global diseases of pines. Disease resistance breeding could be accelerated by knowledge of pathogen virulence factors and their host targets. However, this is hindered due to inefficient targeted gene disruption in D. septosporum, which is required for virulence gene characterisation. Here we report the first successful application of CRISPR/Cas9 gene editing to a Dothideomycete forest pathogen, D. septosporum. Disruption of the dothistromin pathway regulator gene AflR, with a known phenotype, was performed using nonhomologous end-joining repair with an efficiency of > 90%. Transformants with a range of disruption mutations in AflR were produced. Disruption of Ds74283, a D. septosporum gene encoding a secreted cell death elicitor, was also achieved using CRISPR/Cas9, by using a specific donor DNA repair template to aid selection where the phenotype was unknown. In this case, 100% of screened transformants were identified as disruptants. In establishing CRISPR/Cas9 as a tool for gene editing in D. septosporum, our research could fast track the functional characterisation of candidate virulence factors in D. septosporum and helps set the foundation for development of this technology in other forest pathogens.Published onlin
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