674 research outputs found
Bose-Einstein condensation in strong-coupling quark color superconductor near flavor SU(3) limit
Near the flavor SU(3) limit, we propose an analytical description for
color-flavor-locked-type Bardeen-Cooper-Schrieffer (BCS) phase in the Nambu
Jona-Lasinio (NJL) model. The diquark behaviors in light-flavor and
strange-flavor-involved channels and Bose-Einstein condensation (BEC) of bound
diquark states are studied. When the attractive interaction between quarks is
strong enough, a BCS-BEC crossover is predicted in the environment with
color-flavor-locked pairing pattern. The resulting Bose-Einstein condensed
phase is found to be an intergrade phase before the emergence of the
previous-predicted BEC phase in two-flavor quark superconductor.Comment: 15 pages, 5 figures; 2nd versio
Boron-Doped Homoepitaxial Diamond (100) Film Investigated by Scanning Tunneling Microscopy
Conducting epitaxial diamond films of high quality are essential for many diamond studies and diamond electronic device fabrication. We have grown boron-doped epitaxial diamond films on type Ila natural diamond (100) substrates by microwave plasma chemical vapor deposition. A gas mixture of H2/CH4 was used. Boron doping was done by placing solid sources of pure boron in the microwave plasma. Homoepitaxial films with atomic smoothness were achieved under the following growth conditions: substrate temperature 900 °C, gas pressure 40 Torr, and gas flow rates of H2/CH4 = 900/7.2 seem. The growth rate was 0.87 µm/hr. Surfaces of the homoepitaxial films were studied by scanning tunneling microscopy (STM). STM images show smooth and continuous surface with ripple-like features on micrometer scale. On nanometer scale, alternating terraces of 2x1 and 1x2 dimerization were clearly observed
Experimental quantum e-commerce
E-commerce, a type of trading that occurs at a high frequency on the
Internet, requires guaranteeing the integrity, authentication and
non-repudiation of messages through long distance. As current e-commerce
schemes are vulnerable to computational attacks, quantum cryptography, ensuring
information-theoretic security against adversary's repudiation and forgery,
provides a solution to this problem. However, quantum solutions generally have
much lower performance compared to classical ones. Besides, when considering
imperfect devices, the performance of quantum schemes exhibits a significant
decline. Here, for the first time, we demonstrate the whole e-commerce process
of involving the signing of a contract and payment among three parties by
proposing a quantum e-commerce scheme, which shows resistance of attacks from
imperfect devices. Results show that with a maximum attenuation of 25 dB among
participants, our scheme can achieve a signature rate of 0.82 times per second
for an agreement size of approximately 0.428 megabit. This proposed scheme
presents a promising solution for providing information-theoretic security for
e-commerce.Comment: 16 pages, 5 figures, Comments are weclome
Impact of Fibronectin Knockout on Proliferation and Differentiation of Human Infrapatellar Fat Pad-Derived Stem Cells
Fibronectin plays an essential role in tissue development and regeneration. However, the effects of fibronectin knockout (FN1-KO) on stem cells’ proliferation and differentiation remain unknown. In this study, CRISPR/Cas9 generated FN1-KO in human infrapatellar fat pad-derived stem cells (IPFSCs) was evaluated for proliferation ability including cell cycle and surface markers as well as stemness gene expression and for differentiation capacity including chondrogenic and adipogenic differentiation. High passage IPFSCs were also evaluated for proliferation and differentiation capacity after expansion on decellularized ECM (dECM) deposited by FN1-KO cells. Successful FN1-KO in IPFSCs was confirmed by Sanger sequencing and Inference of CRISPR Edits analysis (ICE) as well as immunostaining for fibronectin expression. Compared to the GFP control, FN1-KO cells showed an increase in cell growth, percentage of cells in the S and G2 phases, and CD105 and CD146 expression but a decrease in expression of stemness markers CD73, CD90, SSEA4, and mesenchymal condensation marker CDH2 gene. FN1-KO decreased both chondrogenic and adipogenic differentiation capacity. Interestingly, IPFSCs grown on dECMs deposited by FN1-KO cells exhibited a decrease in cell proliferation along with a decline in CDH2 expression. After induction, IPFSCs plated on dECMs deposited by FN1-KO cells also displayed decreased expression of both chondrogenic and adipogenic capacity. We concluded that FN1-KO increased human IPFSCs’ proliferation capacity; however, this capacity was reversed after expansion on dECM deposited by FN1-KO cells. Significance of fibronectin in chondrogenic and adipogenic differentiation was demonstrated in both FN1-KO IPFSCs and FN(–) matrix microenvironment
Intrinsic-Stabilization Uni-Directional Quantum Key Distribution Between Beijing and Tianjin
Quantum key distribution provides unconditional security for communication.
Unfortunately, current experiment schemes are not suitable for long-distance
fiber transmission because of instability or backscattering. We present a
uni-directional intrinsic-stabilization scheme that is based on
Michelson-Faraday interferometers, in which reflectors are replaced with 90
degree Faraday mirrors. With the scheme, key exchange from Beijing to Tianjin
over 125 kilometers with an average error rate is below 6% has been achieved
and its limited distance exceeds 150 kilometers. Experimental result shows the
system is insensitive to environment and can run over day and night without any
break even in the noise workshop.Comment: 7 pages,4 figure
One-Time Universal Hashing Quantum Digital Signatures without Perfect Keys
Quantum digital signatures (QDS), generating correlated bit strings among
three remote parties for signatures through quantum law, can guarantee
non-repudiation, authenticity, and integrity of messages. Recently, one-time
universal hashing QDS framework, exploiting the quantum asymmetric encryption
and universal hash functions, has been proposed to significantly improve the
signature rate and ensure unconditional security by directly signing the hash
value of long messages. However, similar to quantum key distribution, this
framework utilizes keys with perfect secrecy by performing privacy
amplification that introduces cumbersome matrix operations, thereby consuming
large computational resources, causing delays and increasing failure
probability. Here, we prove that, different from private communication,
imperfect quantum keys with limited information leakage can be used for digital
signatures and authentication without compromising the security while having
eight orders of magnitude improvement on signature rate for signing a megabit
message compared with conventional single-bit schemes. This study significantly
reduces the delay for data postprocessing and is compatible with any quantum
key generation protocols. In our simulation, taking two-photon twin-field key
generation protocol as an example, QDS can be practically implemented over a
fiber distance of 650 km between the signer and receiver. For the first time,
this study offers a cryptographic application of quantum keys with imperfect
secrecy and paves a way for the practical and agile implementation of digital
signatures in a future quantum network.Comment: Comments are welcome
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