20 research outputs found
Fast optical source for quantum key distribution based on semiconductor optical amplifiers
A novel integrated optical source capable of emitting faint pulses with
different polarization states and with different intensity levels at 100 MHz
has been developed. The source relies on a single laser diode followed by four
semiconductor optical amplifiers and thin film polarizers, connected through a
fiber network. The use of a single laser ensures high level of
indistinguishability in time and spectrum of the pulses for the four different
polarizations and three different levels of intensity. The applicability of the
source is demonstrated in the lab through a free space quantum key distribution
experiment which makes use of the decoy state BB84 protocol. We achieved a
lower bound secure key rate of the order of 3.64 Mbps and a quantum bit error
ratio as low as while the lower bound secure key rate
became 187 bps for an equivalent attenuation of 35 dB. To our knowledge, this
is the fastest polarization encoded QKD system which has been reported so far.
The performance, reduced size, low power consumption and the fact that the
components used can be space qualified make the source particularly suitable
for secure satellite communication
New small diameter rotating coil shaft for characterizing new generation of multipolar magnets
HPLC Method Development and Validation for Formaldehyde in Enteric Coating of Hard Gelatin Capsules
NEUROG2 Drives Cell Cycle Exit of Neuronal Precursors by Specifically Repressing a Subset of Cyclins Acting at the G 1
Real-time moving human detection using HOG and Fourier descriptor based on CUDA implementation
Neural crest cells organize the eye via TGF-β and canonical Wnt signalling
In vertebrates, the lens and retina arise from different embryonic tissues raising the question of how they are aligned to form a functional eye. Neural crest cells are crucial for this process: in their absence, ectopic lenses develop far from the retina. Here we show, using the chick as a model system, that neural crest-derived transforming growth factor-ßs activate both Smad3 and canonical Wnt signalling in the adjacent ectoderm to position the lens next to the retina. They do so by controlling Pax6 activity: although Smad3 may inhibit Pax6 protein function, its sustained downregulation requires transcriptional repression by Wnt-initiated ß-catenin. We propose that the same neural crest-dependent signalling mechanism is used repeatedly to integrate different components of the eye and suggest a general role for the neural crest in coordinating central and peripheral parts of the sensory nervous system