5,554 research outputs found
Identification of a recurring bacterial contaminant in a spacecraft watering system
Bacterial contaminant in Biosatellite water syste
The Manchester occulting mask imager (MOMI) - first results on the environment of P Cygni
The design and first use of the Manchester occulting mask imager (MOMI) is
described. This device, when combined with the Cassegrain or Ritchey-Chretien
foci of large telescopes, is dedicated to the imagery of faint line emission
regions around bright central sources.
Initial observations, with MOMI on the Nordic Optical telescope (NOT), of the
V=4.8 mag P~Cygni environment, have revealed a ~5~arcmin long [NII] 6584A
emitting filament projecting from the outer nebular shell of this luminous blue
variable (LBV) star. The presence of a mono-polar lobe older than both the
inner (22 arcsec diameter) and outer (1.6 arcmin diameter) shells is suggested.Comment: 4 pages, 4 figures, accepted MNRAS 1998 June 1
Engineering a flux-dependent mobility edge in disordered zigzag chains
There has been great interest in realizing quantum simulators of charged
particles in artificial gauge fields. Here, we perform the first quantum
simulation explorations of the combination of artificial gauge fields and
disorder. Using synthetic lattice techniques based on parametrically-coupled
atomic momentum states, we engineer zigzag chains with a tunable homogeneous
flux. The breaking of time-reversal symmetry by the applied flux leads to
analogs of spin-orbit coupling and spin-momentum locking, which we observe
directly through the chiral dynamics of atoms initialized to single lattice
sites. We additionally introduce precisely controlled disorder in the site
energy landscape, allowing us to explore the interplay of disorder and large
effective magnetic fields. The combination of correlated disorder and
controlled intra- and inter-row tunneling in this system naturally supports
energy-dependent localization, relating to a single-particle mobility edge. We
measure the localization properties of the extremal eigenstates of this system,
the ground state and the most-excited state, and demonstrate clear evidence for
a flux-dependent mobility edge. These measurements constitute the first direct
evidence for energy-dependent localization in a lower-dimensional system, as
well as the first explorations of the combined influence of artificial gauge
fields and engineered disorder. Moreover, we provide direct evidence for
interaction shifts of the localization transitions for both low- and
high-energy eigenstates in correlated disorder, relating to the presence of a
many-body mobility edge. The unique combination of strong interactions,
controlled disorder, and tunable artificial gauge fields present in this
synthetic lattice system should enable myriad explorations into intriguing
correlated transport phenomena.Comment: 10 pages, 5 figures, 5 pages of supplementary materials; updated
version has additional dat
An assessment of the quality of the I-DSD and the I-CAH registries - international registries for rare conditions affecting sex development
With the proliferation of rare disease registries, there is a need for registries to undergo an assessment of their quality against agreed standards to ensure their long-term sustainability and acceptability.This study was performed to evaluate the I-DSD and I-CAH Registries and identify their strengths and weaknesses. The design and operational aspects of the registries were evaluated against published quality indicators. Additional criteria included the level of activity, international acceptability of the registries and their use for research. The design of the I-DSD and I-CAH Registries provides them with the ability to perform multiple studies and meet the standards for data elements, data sources and eligibility criteria. The registries follow the standards for data security, governance, ethical and legal issues, sustainability and communication of activities. The data have a high degree of validity, consistency and accuracy and the completeness is maximal for specific conditions such as androgen insensitivity syndrome and congenital adrenal hyperplasia. In terms of research output, the external validity is strong but the wide variety of cases needs further review. The internal validity of data was condition specific and highest for conditions such as congenital adrenal hyperplasia. The shift of the registry from a European registry to an international registry and the creation of a discrete but linked CAH registry increased the number of users and stakeholders as well as the international acceptability of both registries. The I-DSD and I-CAH registries comply with the standards set by expert organisations. Recent modifications in their operation have allowed the registries to increase their user acceptability
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