210 research outputs found
Supprimierter Immunstatus durch strukturelle und funktionelle immunologische Defizite bei Patienten mit Karzinomen aus dem Kopf- und Halsbereich
Epidemiologische Daten und Tiermodelle geben Hinweise auf eine verschlechterte Immunabwehr bei Karzinomen des Kopf- und Halsbereiches, wobei die genauen Wirkmechanismen bisher nicht aufgeschlüsselt werden konnten. In Untersuchungen konnte gezeigt werden, dass Karzinome im Kopf- und Halsbereich mit erhöhten Konzentrationen an Prostaglandinen im Serum einhergehen, ein anderer Autor wies eine verminderte Expression des Chemokinrezeptors CCR5 auf Monozyten nach Behandlung mit Prostaglandin nach. In der vorliegenden Arbeit konnte erstmalig aufgezeigt werden, dass es im Rahmen einer Karzinomerkrankung im Hals- und Kopfbereich zu strukturellen und funktionellen Defiziten der Monozytenfunktion kommt. Hierbei finden sich erniedrigte Expressionsraten an CCR5, CCR2 und des Adhäsionsmoleküls CD11b des β-Integrins Mac-1 sowie eine verminderte Adhäsionsfähigkeit der Monozyten an das interzelluläre Adhäsionsmolekül ICAM-1. Weiterhin konnte nachgewiesen werden, dass nach Inkubation der Monozyten in Serum gesunder Spender die verminderte Immunfunktion wieder verbessert wird. Parallel dazu zeigte sich, dass die oben beschriebenen Immundefekte auf Monozyten gesunder Spender durch Inkubation in Serum von Tumorpatienten künstlich herbeigeführt werden können. Dies legt den Schluss nahe, dass im Rahmen einer Karzinomerkrankung Metaboliten im Serum gelöst sind, die eine immunologische Tumorabwehr erschweren. Diese Erkenntnisse sind ein
weiterer Schritt zum Verständnis der Tumorimmunologie und könnten dazu hilfreich sein, immunologische Therapieverfahren voranzubringen
A source of polarization-entangled photon pairs interfacing quantum memories with telecom photons
We present a source of polarization-entangled photon pairs suitable for the
implementation of long-distance quantum communication protocols using quantum
memories. Photon pairs with wavelengths 883 nm and 1338 nm are produced by
coherently pumping two periodically poled nonlinear waveguides embedded in the
arms of a polarization interferometer. Subsequent spectral filtering reduces
the bandwidth of the photons to 240 MHz. The bandwidth is well-matched to a
quantum memory based on an Nd:YSO crystal, to which, in addition, the center
frequency of the 883 nm photons is actively stabilized. A theoretical model
that includes the effect of the filtering is presented and accurately fits the
measured correlation functions of the generated photons. The model can also be
used as a way to properly assess the properties of the source. The quality of
the entanglement is revealed by a visibility of V = 96.1(9)% in a Bell-type
experiment and through the violation of a Bell inequality.Comment: 15 pages, 8 figures, 3 table
Quantum storage of polarization qubits in birefringent and anisotropically absorbing materials
Storage of quantum information encoded into true single photons is an
essential constituent of long-distance quantum communication based on quantum
repeaters and of optical quantum information processing. The storage of
photonic polarization qubits is, however, complicated by the fact that many
materials are birefringent and have polarization-dependent absorption. Here we
present and demonstrate a simple scheme that allows compensating for these
polarization effects. The scheme is demonstrated using a solid-state quantum
memory implemented with an ensemble of rare-earth ions doped into a biaxial
yttrium orthosilicate () crystal. Heralded single photons generated
from a filtered spontaneous parametric downconversion source are stored, and
quantum state tomography of the retrieved polarization state reveals an average
fidelity of , which is significantly higher than what is
achievable with a measure-and-prepare strategy.Comment: 7 pages, 3 figures, 1 table, corrected typos and added ref. 3
Partitioned vs. Integrated Planning of Hinterland Networks for LCL Transportation
Utilizing existing transportation networks better and designing (parts of)
networks involves routing decisions to minimize transportation costs and
maximize consolidation effects. We study the concrete example of hinterland
networks for the truck-transportation of less-than-container-load (LCL) ocean
freight shipments: A set of LCL shipments is given. They have to be routed
through the hinterland network to be transported to an origin port and finally
to the destination port via ship. On their way, they can be consolidated in
hubs to full-container-load (FCL) shipments. The overall transportation cost
depends on the selection of the origin port and the routing and consolidation
in the hinterland network. A problem of this type appears for the global
logistics provider DB Schenker. We translate the business problem into a hub
location problem, describe it mathematically, and discuss solution strategies.
As a result, an integrated modeling approach has several advantages over
solving a simplified version of the problem, although it requires more
computational effort
Quantum teleportation from a telecom-wavelength photon to a solid-state quantum memory
In quantum teleportation, the state of a single quantum system is disembodied
into classical information and purely quantum correlations, to be later
reconstructed onto a second system that has never directly interacted with the
first one. This counterintuitive phenomenon is a cornerstone of quantum
information science due to its essential role in several important tasks such
as the long-distance transmission of quantum information using quantum
repeaters. In this context, a challenge of paramount importance is the
distribution of entanglement between remote nodes, and to use this entanglement
as a resource for long-distance light-to-matter quantum teleportation. Here we
demonstrate quantum teleportation of the polarization state of a
telecom-wavelength photon onto the state of a solid-state quantum memory.
Entanglement is established between a rare-earth-ion doped crystal storing a
single photon that is polarization-entangled with a flying telecom-wavelength
photon. The latter is jointly measured with another flying qubit carrying the
polarization state to be teleported, which heralds the teleportation. The
fidelity of the polarization state of the photon retrieved from the memory is
shown to be greater than the maximum fidelity achievable without entanglement,
even when the combined distances travelled by the two flying qubits is 25 km of
standard optical fibre. This light-to-matter teleportation channel paves the
way towards long-distance implementations of quantum networks with solid-state
quantum memories.Comment: 5 pages (main text) + appendix (10 pages
Three-dimensional self-assembling nanofiber matrix rejuvenates aged/degenerative human tendon stem/progenitor cells
The poor healing capacity of tendons is known to worsen in the elderly. During tendon aging and degeneration,
endogenous human tendon stem/progenitor cells (hTSPCs) experience profound pathological changes. Here, we
explored a rejuvenation strategy for hTSPCs derived from aged/degenerated Achilles tendons (A-TSPCs) by
providing three-dimensional (3D) nanofiber hydrogels and comparing them to young/healthy TSPCs (Y-TSPCs).
RADA peptide hydrogel has a self-assembling ability, forms a nanofibrous 3D niche and can be further functionalized
by adding RGD motifs. Cell survival, apoptosis, and proliferation assays demonstrated that RADA and
RADA/RGD hydrogels support A-TSPCs in a comparable manner to Y-TSPCs. Moreover, they rejuvenated ATSPCs
to a phenotype similar to that of Y-TSPCs, as evidenced by restored cell morphology and cytoskeletal
architecture. Transmission electron, confocal laser scanning and atomic force microscopies demonstrated
comparable ultrastructure, surface roughness and elastic modulus of A- and Y-TSPC-loaded hydrogels. Lastly,
quantitative PCR revealed similar expression profiles, as well a significant upregulation of genes related to
tenogenesis and multipotency. Taken together, the RADA-based hydrogels exert a rejuvenating effect by recapitulating
in vitro specific features of the natural microenvironment of human TSPCs, which strongly indicates
their potential to direct cell behaviour and overcome the challenge of cell aging and degeneration in tendon
repair.D.D. acknowledges the EU Twinning Grant Achilles (H2020-
WIDESPREAD-05-2017-Twinning Grant Nr. 810850). H.Y. thanks for
the support of China Scholarship Council (CSC Grant Nr.
201606200072). S.K. and H.C-S. acknowledge the financial support for
CANTER by the Bavarian State Ministry for Science and Education. The
authors thank Daniela Drenkard for valuable technical assistance and
Dr. Girish Pattappa for English proof-readin
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
Fetal RHD Screening in RH1 Negative Pregnant Women: Experience in Switzerland.
RH1 incompatibility between mother and fetus can cause hemolytic disease of the fetus and newborn. In Switzerland, fetal RHD genotyping from maternal blood has been recommended from gestational age 18 onwards since the year 2020. This facilitates tailored administration of RH immunoglobulin (RHIG) only to RH1 negative women carrying a RH1 positive fetus. Data from 30 months of noninvasive fetal RHD screening is presented. Cell-free DNA was extracted from 7192 plasma samples using a commercial kit, followed by an in-house qPCR to detect RHD exons 5 and 7, in addition to an amplification control. Valid results were obtained from 7072 samples, with 4515 (64%) fetuses typed RHD positive and 2556 (36%) fetuses being RHD negative. A total of 120 samples led to inconclusive results due to the presence of maternal or fetal RHD variants (46%), followed by women being serologically RH1 positive (37%), and technical issues (17%). One sample was typed false positive, possibly due to contamination. No false negative results were observed. We show that unnecessary administration of RHIG can be avoided for more than one third of RH1 negative pregnant women in Switzerland. This reduces the risks of exposure to a blood-derived product and conserves this limited resource to women in actual need
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