3,772 research outputs found
Sub-wavelength terahertz beam profiling of a THz source via an all-optical knife-edge technique
Terahertz technologies recently emerged as outstanding candidates for a variety of applications in such sectors as security, biomedical, pharmaceutical, aero spatial, etc. Imaging the terahertz field, however, still remains a challenge, particularly when sub-wavelength resolutions are involved. Here we demonstrate an all-optical technique for the terahertz near-field imaging directly at the source plane. A thin layer (<100 nm-thickness) of photo carriers is induced on the surface of the terahertz generation crystal, which acts as an all-optical, virtual blade for terahertz near-field imaging via a knife-edge technique. Remarkably, and in spite of the fact that the proposed approach does not require any mechanical probe, such as tips or apertures, we are able to demonstrate the imaging of a terahertz source with deeply sub-wavelength features (<30 μm) directly in its emission plane
Molecular basis for the folding of β-helical autotransporter passenger domains
Bacterial autotransporters comprise a C-terminal β-barrel domain, which must be correctly folded and inserted into the outer membrane to facilitate translocation of the N-terminal passenger domain to the cell exterior. Once at the surface, the passenger domains of most autotransporters are folded into an elongated β-helix. In a cellular context, key molecules catalyze the assembly of the autotransporter β-barrel domain. However, how the passenger domain folds into its functional form is poorly understood. Here we use mutational analysis on the autotransporter Pet to show that the β-hairpin structure of the fifth extracellular loop of the β-barrel domain has a crucial role for passenger domain folding into a β-helix. Bioinformatics and structural analyses, and mutagenesis of a homologous autotransporter, suggest that this function is conserved among autotransporter proteins with β-helical passenger domains. We propose that the autotransporter β-barrel domain is a folding vector that nucleates folding of the passenger domain
A portrait of the immune response to proliferative kidney disease (PKD) in rainbow trout
This work was supported by the European Commission under the Horizon H2020 research and innovation programme (Grant H2020‐634429 ParaFishControl) and by the European Research Council (ERC Consolidator Grant 2016 725061 TEMUBLYM). CB was supported by the SNSF Post‐Doc Mobility grant P400PB_183824.Peer reviewedPublisher PD
Experimental demonstration of a BDCZ quantum repeater node
Quantum communication is a method that offers efficient and secure ways for
the exchange of information in a network. Large-scale quantum communication (of
the order of 100 km) has been achieved; however, serious problems occur beyond
this distance scale, mainly due to inevitable photon loss in the transmission
channel. Quantum communication eventually fails when the probability of a dark
count in the photon detectors becomes comparable to the probability that a
photon is correctly detected. To overcome this problem, Briegel, D\"{u}r, Cirac
and Zoller (BDCZ) introduced the concept of quantum repeaters, combining
entanglement swapping and quantum memory to efficiently extend the achievable
distances. Although entanglement swapping has been experimentally demonstrated,
the implementation of BDCZ quantum repeaters has proved challenging owing to
the difficulty of integrating a quantum memory. Here we realize entanglement
swapping with storage and retrieval of light, a building block of the BDCZ
quantum repeater. We follow a scheme that incorporates the strategy of BDCZ
with atomic quantum memories. Two atomic ensembles, each originally entangled
with a single emitted photon, are projected into an entangled state by
performing a joint Bell state measurement on the two single photons after they
have passed through a 300-m fibre-based communication channel. The entanglement
is stored in the atomic ensembles and later verified by converting the atomic
excitations into photons. Our method is intrinsically phase insensitive and
establishes the essential element needed to realize quantum repeaters with
stationary atomic qubits as quantum memories and flying photonic qubits as
quantum messengers.Comment: 5 pages, 4 figure
Physics Opportunities of e+e- Linear Colliders
We describe the anticipated experimental program of an e+e- linear collider
in the energy range 500 GeV -- 1.5 TeV. We begin with a description of current
collider designs and the expected experimental environment. We then discuss
precision studies of the W boson and top quark. Finally, we review the range of
models proposed to explain the physics of electroweak symmetry breaking and
show, for each case, the central role that the linear collider experiments will
play in elucidating this physics. (to appear in Annual Reviews of Nuclear and
Particle Science)Comment: 93 pages, latex + 23 figures; typos corrections + 1 reference adde
Risk of congenital anomalies in pregnant users of statin drugs
What is already known about this subjectCholesterol is known to be essential for fetal development.Statins, which inhibit cholesterol production, have therefore been considered as potential teratogens and are contraindicated in pregnancy.Data available thus far on the risks of congenital anomalies associated with statin therapy have come from non-analytic postmarketing surveillance studies.Given the increasing use of statins in women of childbearing age, there is a need for a population-based study on the risks of congenital anomalies associated with gestational statin use.What this study addsIn this pharmacoepidemiological study, we determined the risk of congenital anomalies in women who filled prescriptions for statins during the first trimester of pregnancy, compared with women who had stopped statins before pregnancy or those who used fibrates during pregnancy.We found no evidence of an increased risk of fetal anomalies among first-trimester statin users, or any discernable pattern of congenital anomalies among live births.However, in the absence of outcome data on nonlive births, conclusions remain uncertain
Heralded quantum entanglement between two crystals
Quantum networks require the crucial ability to entangle quantum nodes. A
prominent example is the quantum repeater which allows overcoming the distance
barrier of direct transmission of single photons, provided remote quantum
memories can be entangled in a heralded fashion. Here we report the observation
of heralded entanglement between two ensembles of rare-earth-ions doped into
separate crystals. A heralded single photon is sent through a 50/50
beamsplitter, creating a single-photon entangled state delocalized between two
spatial modes. The quantum state of each mode is subsequently mapped onto a
crystal, leading to an entangled state consisting of a single collective
excitation delocalized between two crystals. This entanglement is revealed by
mapping it back to optical modes and by estimating the concurrence of the
retrieved light state. Our results highlight the potential of rare-earth-ions
doped crystals for entangled quantum nodes and bring quantum networks based on
solid-state resources one step closer.Comment: 10 pages, 5 figure
Success Factors of European Syndromic Surveillance Systems: A Worked Example of Applying Qualitative Comparative Analysis
Introduction: Syndromic surveillance aims at augmenting traditional public health surveillance with timely information. To gain a head start, it mainly analyses existing data such as from web searches or patient records. Despite the setup of many syndromic surveillance systems, there is still much doubt about the benefit of the approach. There are diverse interactions between performance indicators such as timeliness and various system characteristics. This makes the performance assessment of syndromic surveillance systems a complex endeavour. We assessed if the comparison of several syndromic surveillance systems through Qualitative Comparative Analysis helps to evaluate performance and identify key success factors.
Materials and Methods: We compiled case-based, mixed data on performance and characteristics of 19 syndromic surveillance systems in Europe from scientific and grey literature and from site visits. We identified success factors by applying crisp-set Qualitative Comparative Analysis. We focused on two main areas of syndromic surveillance application: seasonal influenza surveillance and situational awareness during different types of potentially health threatening events.
Results: We found that syndromic surveillance systems might detect the onset or peak of seasonal influenza earlier if they analyse non-clinical data sources. Timely situational awareness during different types of events is supported by an automated syndromic surveillance system capable of analysing multiple syndromes. To our surprise, the analysis of multiple data sources was no key success factor for situational awareness.
Conclusions: We suggest to consider these key success factors when designing or further developing syndromic surveillance systems. Qualitative Comparative Analysis helped interpreting complex, mixed data on small-N cases and resulted in concrete and practically relevant findings
Interleukin 7 from Maternal Milk Crosses the Intestinal Barrier and Modulates T- Cell Development in Offspring
Background
Breastfeeding protects against illnesses and death in hazardous environments, an
effect partly mediated by improved immune function. One hypothesis suggests that
factors within milk supplement the inadequate immune response of the offspring,
but this has not been able to account for a series of observations showing that
factors within maternally derived milk may supplement the development of the
immune system through a direct effect on the primary lymphoid organs. In a
previous human study we reported evidence suggesting a link between IL-7 in
breast milk and the thymic output of infants. Here we report evidence in mice of
direct action of maternally-derived IL-7 on T cell development in the offspring.
Methods and Findings
We have used recombinant IL-7 labelled with a fluorescent dye to trace the
movement in live mice of IL-7 from the stomach across the gut and into the
lymphoid tissues. To validate the functional ability of maternally derived IL-
7 we cross fostered IL-7 knock-out mice onto normal wild type mothers. Subsets
of thymocytes and populations of peripheral T cells were significantly higher
than those found in knock-out mice receiving milk from IL-7 knock-out mothers.
Conclusions/Significance Our study provides direct evidence that interleukin 7,
a factor which is critical in the development of T lymphocytes, when maternally
derived can transfer across the intestine of the offspring, increase T cell
production in the thymus and support the survival of T cells in the peripheral
secondary lymphoid tissue
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