199 research outputs found
50 Tbit/s Massively ParallelWDMTransmission in C and L Band Using Interleaved Cavity-Soliton Kerr Combs
Interleaving two soliton Kerr combs we generate 179 carriers for WDM transmission and demonstrate transmission of a data stream of 50 Tbit/s over 75 km. This is the highest data rate achieved with a chip-scale comb source
OA031-04. Impairment of HIV-1-specific CD8+ T cell function by soluble epithelial adhesion molecules
The tunnel magnetoresistance in chains of quantum dots weakly coupled to external leads
We analyze numerically the spin-dependent transport through coherent chains
of three coupled quantum dots weakly connected to external magnetic leads. In
particular, using the diagrammatic technique on the Keldysh contour, we
calculate the conductance, shot noise and tunnel magnetoresistance (TMR) in the
sequential and cotunneling regimes. We show that transport characteristics
greatly depend on the strength of the interdot Coulomb correlations, which
determines the spacial distribution of electron wave function in the chain.
When the correlations are relatively strong, depending on the transport regime,
we find both negative TMR as well as TMR enhanced above the Julliere value,
accompanied with negative differential conductance (NDC) and super-Poissonian
shot noise. This nontrivial behavior of tunnel magnetoresistance is associated
with selection rules that govern tunneling processes and various high-spin
states of the chain that are relevant for transport. For weak interdot
correlations, on the other hand, the TMR is always positive and not larger than
the Julliere TMR, although super-Poissonian shot noise and NDC can still be
observed
The communities of ectomycorrhizal fungal species associated with Betula pendula ROTH and Pinus sylvestris L. growing in heavy-metal contaminated soils
Aims Pioneer tree species such as Betula pendula and
Pinus sylvestris encroach soils contaminated with heavy
metals (HMs). This is facilitated by ectomycorrhizal
fungi colonizing tree roots. Thus, we evaluated the
ectomycorrhizal fungal (EMF) communities of
B. pendula and P. sylvestris growing in HMcontaminated
soils compared to non-contaminated soils.
We also studied the effect of HMs and soil properties on
EMF communities and soil fungal biomass.
Methods Roots of B. pendula and P. sylvestris were
collected from three HM-contaminated sites and from
two non-contaminated sites located in Poland. EMF
species were identified using DNA barcoding. Soil fungal
biomass was determined by soil ergosterol.
Results B. pendula and P. sylvestris growing in HMcontaminated
soils had similar EMF communities,
where Scleroderma, Rhizopogon and Russula as well
as ectomycorrhizae of the long-distance exploration
type dominated. Among all of the examined soil factors
studied, toxicity index (TITotal) was the most significant
factor shaping the composition of EMF communities.
Despite significant differences in the structure of the
EMF communities of trees growing in HMcontaminated
sites compared to control sites, no differences
in overall diversity were observed.
Conclusions Only well-adapted EMF species can survive
toxic conditions and form ectomycorrhizal symbiosis
with encroaching trees facilitating the forest succession
on contaminated soils
Significance of differential expression of thymidylate synthase in normal and primary tumor tissues from patients with colorectal cancer
The role of thymidylate synthase (TS) is essential as a key rate-limiting enzyme in DNA synthesis. It is the primary target of fluorouracil and its derivates in colorectal cancer. In this study, TS mRNA expression was examined in primary tumor and normal tissues from 76 patients with high- risk stage II/III colorectal cancer by laser capture microdissection and polymerase chain reaction. Thirty (39.47%) patients were found to have higher TS expression in primary tumors with earlier stage (P = 0.018), lower histological grades (P = 0.001) and high frequency microsatellite instability (P = 0.000). Multivariate analysis showed that microsatellite instability, histological grade and number of lymph nodes examined are independent prognostic markers
Searching for Exoplanets Using a Microresonator Astrocomb
Detection of weak radial velocity shifts of host stars induced by orbiting
planets is an important technique for discovering and characterizing planets
beyond our solar system. Optical frequency combs enable calibration of stellar
radial velocity shifts at levels required for detection of Earth analogs. A new
chip-based device, the Kerr soliton microcomb, has properties ideal for
ubiquitous application outside the lab and even in future space-borne
instruments. Moreover, microcomb spectra are ideally suited for astronomical
spectrograph calibration and eliminate filtering steps required by conventional
mode-locked-laser frequency combs. Here, for the calibration of astronomical
spectrographs, we demonstrate an atomic/molecular line-referenced,
near-infrared soliton microcomb. Efforts to search for the known exoplanet HD
187123b were conducted at the Keck-II telescope as a first in-the-field
demonstration of microcombs
Coherent WDM transmission using quantum-dash mode-locked laser diodes as multi-wavelength source and local oscillator
Quantum-dash (QD) mode-locked laser diodes (MLLD) lend themselves as
chip-scale frequency comb generators for highly scalable wavelength-division
multiplexing (WDM) links in future data-center, campus-area, or metropolitan
networks. Driven by a simple DC current, the devices generate flat broadband
frequency combs, containing tens of equidistant optical tones with line
spacings of tens of GHz. Here we show that QD-MLLDs can not only be used as
multi-wavelength light sources at a WDM transmitter, but also as
multi-wavelength local oscillators (LO) for parallel coherent reception. In our
experiments, we demonstrate transmission of an aggregate data rate of 4.1
Tbit/s (23x45 GBd PDM-QPSK) over 75 km standard single-mode fiber (SSMF). To
the best of our knowledge, this represents the first demonstration of a
coherent WDM link that relies on QD-MLLD both at the transmitter and the
receiver
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