36 research outputs found
Detection of Tropheryma whippelii DNA in a patient with AIDS
A case of an AIDS patient infected with the Whipple's disease bacterium, Tropheryma whippelii, is reported. A DNA fragment with sequence specificity for the 16S rRNA gene of the bacterium was detected by PCR in a duodenal biopsy specimen from a 55-year-old male patient with AIDS and diarrhea. The biopsy specimen contained periodic acid-Schiff stain-positive macrophages which did not, however, resemble the sickleform-particle-containing cells characteristic of Whipple's disease. This observation raises two possibilities: either the patient had a coincidence of AIDS and Whipple's disease or Tropheryma whippelii acted as an opportunistic pathogen in this immunodeficient patient. The latter explanation is of interest in light of the ongoing discussion of immunologic abnormalities as predisposing factors for Whipple's disease
Effects of closed-loop automatic control of the inspiratory fraction of oxygen (FiO(2)-C) on outcome of extremely preterm infants - study protocol of a randomized controlled parallel group multicenter trial for safety and efficacy
Background: Most extremely low gestational age neonates (ELGANS, postmenstrual age at birth (PMA) < 28
completed weeks) require supplemental oxygen and experience frequent intermittent hypoxemic and hyperoxemic
episodes. Hypoxemic episodes and exposure to inadequately high concentrations of oxygen are associated with an
increased risk of retinopathy of prematurity (ROP), chronic lung disease of prematurity (BPD), necrotizing
enterocolitis (NEC), neurodevelopmental impairment (NDI), and death beyond 36 weeks PMA.
Closed-loop automated control of the inspiratory fraction of oxygen (FiO2-C) reduces time outside the hemoglobin
oxygen saturation (SpO2) target range, number and duration of hypo- and hyperoxemic episodes and caregivers’
workload. Effects on clinically important outcomes in ELGANs such as ROP, BPD, NEC, NDI and mortality have not
yet been studied.
Methods: An outcome-assessor-blinded, randomized controlled, parallel-group trial was designed and powered to
study the effect of FiO2-C (in addition to routine manual control (RMC) of FiO2), compared to RMC only, on death
and severe complications related to hypoxemia and/or hyperoxemia. 2340 ELGANS with a GA of 23 + 0/7 to 27 + 6/
7 weeks will be recruited in approximately 75 European tertiary care neonatal centers. Study participants are
randomly assigned to RMC (control-group) or FiO2-C in addition to RMC (intervention-group). Central
randomization is stratified for center, gender and PMA at birth (< 26 weeks and ≥ 26 weeks).
FiO2-C is provided by commercially available and CE-marked ventilators with an FiO2-C algorithm intended for use
in newborn infants. The primary outcome variable (composite of death, severe ROP, BPD or NEC) is assessed at 36
weeks PMA (or, in case of ROP, until complete vascularization of the retina, respectively). The co-primary outcome
variable (composite outcome of death, language/cognitive delay, motor impairment, severe visual impairment or
hearing impairment) is assessed at 24 months corrected age. Discussion: Short-term studies on FiO2-C showed improved time ELGANs spent within their assigned SpO2 target
range, but effects of FiO2-C on clinical outcomes are yet unknown and will be addressed in the FiO2-C trial. This will
ensure an appropriate assessment of safety and efficacy before FiO2-C may be implemented as standard therap
Ultrasensitive force and displacement detection using trapped ions
The ability to detect extremely small forces is vital for a variety of
disciplines including precision spin-resonance imaging, microscopy, and tests
of fundamental physical phenomena. Current force-detection sensitivity limits
have surpassed 1 (atto ) through coupling of micro or
nanofabricated mechanical resonators to a variety of physical systems including
single-electron transistors, superconducting microwave cavities, and individual
spins. These experiments have allowed for probing studies of a variety of
phenomena, but sensitivity requirements are ever-increasing as new regimes of
physical interactions are considered. Here we show that trapped atomic ions are
exquisitely sensitive force detectors, with a measured sensitivity more than
three orders of magnitude better than existing reports. We demonstrate
detection of forces as small as 174 (yocto ), with a
sensitivity 390 using crystals of Be
ions in a Penning trap. Our technique is based on the excitation of normal
motional modes in an ion trap by externally applied electric fields, detection
via and phase-coherent Doppler velocimetry, which allows for the discrimination
of ion motion with amplitudes on the scale of nanometers. These experimental
results and extracted force-detection sensitivities in the single-ion limit
validate proposals suggesting that trapped atomic ions are capable of detecting
of forces with sensitivity approaching 1 . We anticipate that
this demonstration will be strongly motivational for the development of a new
class of deployable trapped-ion-based sensors, and will permit scientists to
access new regimes in materials science.Comment: Expanded introduction and analysis. Methods section added. Subject to
press embarg
Heralded single photon absorption by a single atom
The emission and absorption of single photons by single atomic particles is a
fundamental limit of matter-light interaction, manifesting its quantum
mechanical nature. At the same time, as a controlled process it is a key
enabling tool for quantum technologies, such as quantum optical information
technology [1, 2] and quantum metrology [3, 4, 5, 6]. Controlling both emission
and absorption will allow implementing quantum networking scenarios [1, 7, 8,
9], where photonic communication of quantum information is interfaced with its
local processing in atoms. In studies of single-photon emission, recent
progress includes control of the shape, bandwidth, frequency, and polarization
of single-photon sources [10, 11, 12, 13, 14, 15, 16, 17], and the
demonstration of atom-photon entanglement [18, 19, 20]. Controlled absorption
of a single photon by a single atom is much less investigated; proposals exist
but only very preliminary steps have been taken experimentally such as
detecting the attenuation and phase shift of a weak laser beam by a single atom
[21, 22], and designing an optical system that covers a large fraction of the
full solid angle [23, 24, 25]. Here we report the interaction of single
heralded photons with a single trapped atom. We find strong correlations of the
detection of a heralding photon with a change in the quantum state of the atom
marking absorption of the quantum-correlated heralded photon. In coupling a
single absorber with a quantum light source, our experiment demonstrates
previously unexplored matter-light interaction, while opening up new avenues
towards photon-atom entanglement conversion in quantum technology.Comment: 10 pages, 4 figure
Reduced plantar sensation leads to heterogeneous reactions in plantar pressure distribution during normal walking
Ion traps with enhanced optical and physical access
Small, controllable, highly accessible quantum systems can serve as probes at
the single quantum level to study multiple physical effects, for example in
quantum optics or for electric and magnetic field sensing. The applicability of
trapped atomic ions as probes is highly dependent on the measurement situation
at hand and thus calls for specialized traps. Previous approaches for ion traps
with enhanced optical access included traps consisting of a single ring
electrode or two opposing endcap electrodes. Other possibilities are planar
trap geometries, which have been investigated for Penning traps and rf-trap
arrays. By not having the electrodes lie in a common plane the optical access
in the latter cases can be substantially increased. Here, we discuss the
fabrication and experimental characterization of a novel radio-frequency (rf)
ion trap geometry. It has a relatively simple structure and provides largely
unrestricted optical and physical access to the ion, of up to 96% of the total
4pi solid angle in one of the three traps tested. We also discuss potential
applications in quantum optics and field sensing. As a force sensor, we
estimate sensitivity to forces smaller than 1 yN Hz^(-1/2).Comment: 6 pages, 3 figures. Corrections of some typos, application section
expanded to account for reviewer comment
Photon-Atom Coupling with Parabolic Mirrors
Efficient coupling of light to single atomic systems has gained considerable
attention over the past decades. This development is driven by the continuous
growth of quantum technologies. The efficient coupling of light and matter is
an enabling technology for quantum information processing and quantum
communication. And indeed, in recent years much progress has been made in this
direction. But applications aside, the interaction of photons and atoms is a
fundamental physics problem. There are various possibilities for making this
interaction more efficient, among them the apparently 'natural' attempt of
mode-matching the light field to the free-space emission pattern of the atomic
system of interest. Here we will describe the necessary steps of implementing
this mode-matching with the ultimate aim of reaching unit coupling efficiency.
We describe the use of deep parabolic mirrors as the central optical element of
a free-space coupling scheme, covering the preparation of suitable modes of the
field incident onto these mirrors as well as the location of an atom at the
mirror's focus. Furthermore, we establish a robust method for determining the
efficiency of the photon-atom coupling.Comment: Book chapter in compilation "Engineering the Atom-Photon Interaction"
published by Springer in 2015, edited by A. Predojevic and M. W. Mitchell,
ISBN 9783319192307, http://www.springer.com/gp/book/9783319192307. Only
change to version1: now with hyperlinks to arXiv eprints of other book
chapters mentioned in this on
RKappa: Statistical sampling suite for Kappa models
We present RKappa, a framework for the development and analysis of rule-based
models within a mature, statistically empowered R environment. The
infrastructure allows model editing, modification, parameter sampling,
simulation, statistical analysis and visualisation without leaving the R
environment. We demonstrate its effectiveness through its application to Global
Sensitivity Analysis, exploring it in "parallel" and "concurrent"
implementations.
The pipeline was designed for high performance computing platforms and aims
to facilitate analysis of the behaviour of large-scale systems with limited
knowledge of exact mechanisms and respectively sparse availability of parameter
values, and is illustrated here with two biological examples.
The package is available on github: https://github.com/lptolik/R4KappaComment: Hybrid Systems and Biology 2014, Vienn