454 research outputs found
Unconventional superconductivity in a doped quantum spin Hall insulator
A monolayer of jacutingaite (PtHgSe) has recently been identified as
a novel quantum spin Hall insulator. By first-principles calculations, we study
its Fermiology in the doped regime and unveil a type-I and type-II van Hove
singularity for hole and electron doping, respectively. We find that the common
link between the propensity for a topological band gap at pristine filling and
unconventional superconductivity at finite doping roots in the longer ranged
hybridization integrals on the honeycomb lattice. In a combined effort of
random phase approximation and functional renormalization group, we find chiral
-wave order for the type-I and odd-parity -wave order for the type-II
regime.Comment: 5 pages, 4 figures, Supplemental Materia
Twisted Light Transmission over 143 kilometers
Spatial modes of light can potentially carry a vast amount of information,
making them promising candidates for both classical and quantum communication.
However, the distribution of such modes over large distances remains difficult.
Intermodal coupling complicates their use with common fibers, while free-space
transmission is thought to be strongly influenced by atmospheric turbulence.
Here we show the transmission of orbital angular momentum modes of light over a
distance of 143 kilometers between two Canary Islands, which is 50 times
greater than the maximum distance achieved previously. As a demonstration of
the transmission quality, we use superpositions of these modes to encode a
short message. At the receiver, an artificial neural network is used for
distinguishing between the different twisted light superpositions. The
algorithm is able to identify different mode superpositions with an accuracy of
more than 80% up to the third mode order, and decode the transmitted message
with an error rate of 8.33%. Using our data, we estimate that the distribution
of orbital angular momentum entanglement over more than 100 kilometers of free
space is feasible. Moreover, the quality of our free-space link can be further
improved by the use of state-of-the-art adaptive optics systems.Comment: 12 pages, 4 figure
Twisted photon entanglement through turbulent air across Vienna
Photons with a twisted phase front can carry a discrete, in principle
unbounded amount of orbital angular momentum (OAM). The large state space
allows for complex types of entanglement, interesting both for quantum
communication and for fundamental tests of quantum theory. However, the
distribution of such entangled states over large distances was thought to be
infeasible due to influence of atmospheric turbulence, indicating a serious
limitation on their usefulness. Here we show that it is possible to distribute
quantum entanglement encoded in OAM over a turbulent intra-city link of 3
kilometers. We confirm quantum entanglement of the first two higher-order
levels (with OAM= and ). They correspond to four new
quantum channels orthogonal to all that have been used in long-distance quantum
experiments so far. Therefore a promising application would be quantum
communication with a large alphabet. We also demonstrate that our link allows
access to up to 11 quantum channels of OAM. The restrictive factors towards
higher numbers are technical limitations that can be circumvented with readily
available technologies.Comment: 11 pages, 4 figure
Insights into Early-Pregnancy Mechanisms: Mast Cells and Chymase CMA1 Shape the Phenotype and Modulate the Functionality of Human Trophoblast Cells, Vascular Smooth-Muscle Cells and Endothelial Cells
Spiral-artery (SA) remodeling is a fundamental process during pregnancy that involves the
action of cells of the initial vessel, such as vascular smooth-muscle cells (VSMCs) and endothelial
cells, but also maternal immune cells and fetal extravillous trophoblast cells (EVTs). Mast cells
(MCs), and specifically chymase-expressing cells, have been identified as key to a sufficient SA remodeling process in vivo. However, the mechanisms are still unclear. The purpose of this study
is to evaluate the effects of the MC line HMC-1 and recombinant human chymase (rhuCMA1)
on human primary uterine vascular smooth-muscle cells (HUtSMCs), a human trophoblast cell
line (HTR8/SV-neo), and human umbilical-vein endothelial cells (HUVEC) in vitro. Both HMC-1
and rhuCMA1 stimulated migration, proliferation, and changed protein expression in HUtSMCs.
HMC-1 increased proliferation, migration, and changed gene expression of HTR8/SVneo cells, while
rhuCMA treatment led to increased migration and decreased expression of tissue inhibitors of matrix
metalloproteinases. Additionally, rhuCMA1 enhanced endothelial-cell-tube formation. Collectively,
we identified possible mechanisms by which MCs/rhuCMA1 promote SA remodeling. Our findings
are relevant to the understanding of this crucial step in pregnancy and thus of the dysregulated
pathways that can lead to pregnancy complications such as fetal growth restriction and preeclampsia
Prikazi, ocjene, osvrti
Prikazi, ocjene, osvrt
Communication with spatially modulated Light through turbulent Air across Vienna
The transverse spatial modes of light offer a large state-space with
interesting physical properties. For exploiting it in future long-distance
experiments, spatial modes will have to be transmitted over turbulent
free-space links. Numerous recent lab-scale experiments have found significant
degradation in the mode quality after transmission through simulated turbulence
and consecutive coherent detection. Here we experimentally analyze the
transmission of one prominent class of spatial modes, the orbital-angular
momentum (OAM) modes, through 3 km of strong turbulence over the city of
Vienna. Instead of performing a coherent phase-dependent measurement, we employ
an incoherent detection scheme which relies on the unambiguous intensity
patterns of the different spatial modes. We use a pattern recognition algorithm
(an artificial neural network) to identify the characteristic mode pattern
displayed on a screen at the receiver. We were able to distinguish between 16
different OAM mode superpositions with only ~1.7% error, and use them to encode
and transmit small grey-scale images. Moreover, we found that the relative
phase of the superposition modes is not affected by the atmosphere,
establishing the feasibility for performing long-distance quantum experiments
with the OAM of photons. Our detection method works for other classes of
spatial modes with unambiguous intensity patterns as well, and can further be
improved by modern techniques of pattern recognition.Comment: 11 pages, 4 figure
Development of the front-end electronics for a cost-effective PET-like detector system
Most detector systems used for positron emission particle tracking (PEPT) are
very expensive due to the use of inorganic plastic scintillators combined with
a high number of readout electronic channels. This work aims to reduce the
overall cost of a PEPT-capable detector system by using large and
cost-effective plastic scintillators and developing custom 2 x 2 silicon
photomultiplier (SiPM) arrays, preamplifiers, and discriminators. The use of
long (20 mm x 20 mm x 1000 mm) plastic scintillator bars read out with
photodetectors only at their respective ends allows an overall smaller number
of photodetectors and associated readout electronics, which in turn reduces the
overall cost of the system. In addition, the development of a custom SiPM array
and preamplifier allows a free selection of interconnection and readout, as
most commercial producers only offer specific types of interconnections and
therefore lack other connections such as serial or hybrid. Thus, several common
circuit types for SiPMs and preamplifiers were tested and compared in this
work, and it was found that a serial connection implemented in a hybrid
interconnection for the SiPMs and an inverting preamplifier based on a
high-frequency operational amplifier provided the best results for the proposed
detector system. Measured with a Na-22 source, the combination of SiPM array
and preamplifier led to a rise time of 3.7 ns and a signal amplitude of 175 mV.Comment: Published in Nuclear Instruments and Methods in Physics Research A
1057 (2023) 168767. This manuscript version is made available under the
CC-BY-NC-ND 4.0 licens
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