880 research outputs found
Experimental high-intensity three-photon entangled source
We experimentally realize a high-intensity three-photon
Greenberger-Horne-Zeilinger (GHZ) entanglement source directly following the
proposal by Rarity and Tapster [J. G. Rarity and P. R. Tapster, Phys. Rev. A
59, R35 (1999)]. The threefold coincidence rate can be more than 200 Hz with a
fidelity of 0.811, and the intensity can be further improved with moderate
fidelity degradation. The GHZ entanglement is characterized by testing the
Bell-Mermin inequality and using an entanglement witness operator. To optimize
the polarization-entangled source, we theoretically analyze the relationship
between the mean photon number of the single-photon source and the probability
of parametric down-conversion.Comment: 4 pages, 4 figure
Bis{μ-2-[1-(2-PyridylmethylÂimino)ethÂyl]phenolato}bisÂ[azidoÂcopper(II)]
The title compound, [Cu2(C14H13N2O)2(N3)2], was synthesized by the reaction of Cu(NO3)2·3H2O with the Schiff base 2-[1-(2-pyridylmethylÂimino)ethÂyl]phenol (HL) in methanol–water solution, adding NaN3 as the bridging ligand. The asymmetric unit contains one half-molÂecule, the other half being generated by the inversion center. Each CuII atom shows a slightly distorted trigonal-pyramidal geometry formed by two N atoms and one O atom from one Schiff base ligand, by another O atom of a second Schiff base ligand and by an azide N atom. The crystal structure is stabilized by intermolecular C—H⋯N hydrogen bonds
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Strict Major Histocompatibility Complex Molecule Class-Specific Binding by Co-Receptors Enforces MHC-Restricted αβ TCR Recognition during T Lineage Subset Commitment
Since the discovery of co-receptor dependent αβTCR recognition, considerable effort has been spent on elucidating the basis of CD4 and CD8 lineage commitment in the thymus. The latter is responsible for generating mature CD4 helper and CD8αβ cytotoxic T cell subsets. Although CD4+ and CD8+ T cell recognition of peptide antigens is known to be MHC class II- and MHC class I-restricted, respectively, the mechanism of single positive (SP) thymocyte lineage commitment from bipotential double-positive (DP) progenitors is not fully elucidated. Classical models to explain thymic CD4 vs. CD8 fate determination have included a stochastic selection model or instructional models. The latter are based either on strength of signal or duration of signal impacting fate. More recently, differential co-receptor gene imprinting has been shown to be involved in expression of transcription factors impacting cytotoxic T cell development. Here, we address commitment from a structural perspective, focusing on the nature of co-receptor binding to MHC molecules. By surveying 58 MHC class II and 224 MHC class I crystal structures in the Protein Data Bank, it becomes clear that CD4 cannot bind to MHC I molecules, nor can CD8αβ or CD8αα bind to MHC II molecules. Given that the co-receptor delivers Lck to phosphorylate exposed CD3 ITAMs within a peptide/MHC (pMHC)-ligated TCR complex to initiate cell signaling, this strict co-receptor recognition fosters MHC class-restricted SP thymocyte lineage commitment at the DP stage even though both co-receptors are expressed on a single cell. In short, the binding preference of an αβTCR for a peptide complexed with an MHC molecule dictates which co-receptor subsequently binds, thereby supporting development of that subset lineage. How function within the lineage is linked further to biopotential fate determination is discussed
Internet Of Rights(IOR) In Role Based Block Chain
A large amount of data has been accumulated. with the development of the
Internet industry. Many problems have been exposed with data explosion: 1. The
contradiction between data privacy and data collaborations; 2. The
contradiction between data ownership and the right of data usage; 3. The
legality of data collection and data usage; 4. The relationship between the
governance of data and the governance of rules; 5. Traceability of evidence
chain. In order to face such a complicated situation, many algorithms were
proposed and developed. This article tries to build a model from the
perspective of blockchain to make some breakthroughs.Internet Of Rights(IOR)
model uses multi-chain technology to logically break down the consensus
mechanism into layers, including storage consensus, permission consensus, role
consensus, transaction consensus etc. thus to build a new infrastructure, which
enables data sources with complex organizational structures and interactions to
collaborate smoothly on the premise of protecting data privacy. With
blockchain's nature of decentralization, openness, autonomy, immutability, and
controllable anonymity, Internet Of Rights(IOR) model registers the ownership
of data, enables applications to build ecosystem based on responsibilities and
rights. It also provides cross-domain processing with privacy protection, as
well as the separation of data governance and rule governance. With the
processing capabilities of artificial intelligence and big data technology, as
well as the ubiquitous data collection capabilities of the Internet of Things,
Internet Of Rights(IOR) model may provide a new infrastructure concept for
realizing swarm intelligence and building a new paradigm of the Internet, i.e.
intelligent governance
Effects of low-molecular-weight heparin and unfractionated heparin on traumatic disseminated intravascular coagulation
Purpose: To explore the effects of unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) on traumatic disseminated intravascular coagulation (DIC).Methods: A total of 77 cases of severe trauma (APACHE II score: 5 – 10) with DIC were collected and randomly assigned to one of three groups: LMWH treatment - 26 cases were subcutaneously injected with LMWH (75–150 units/kg/d); UFH treatment - 25 cases were subcutaneously injected with UFH (100 – 250 units/kg/d); control - 26 cases supplemented with blood coagulation factor only. Daily mortality in the intensive care unit (ICU), hospitalization time, bleeding rate, thrombin time, prothrombin time, activated partial thromboplastin time, and levels of fibrinogen, antithrombin III (ATIII), and D-dimer were recorded and analyzed.Results: In ICU, LMWH and UFH treatments resulted in lower mortality than in the control group. In addition, hospitalization time was longer in patients treated with LMWH and UFH than in control patients. No significant differences were found between LMWH-treated and control patients in terms of bleeding rate, but UFH-treated patients had lower bleeding rates than control patients. Multifactor analysis indicate a strong relationship between ATIII levels and bleeding rate.Conclusion: The results indicate that low-dose UFH and LMWH are effective options for the treatment of DIC.Keywords: Trauma, Disseminated intravascular coagulation, Unfractionated heparin, Low-molecularweight heparin, Fibrinogen, Antithrombi
Modulation of the thermodynamic, kinetic and magnetic properties of the hydrogen monomer on graphene by charge doping
The thermodynamic, kinetic and magnetic properties of the hydrogen monomer on
doped graphene layers were studied by ab initio simulations. Electron doping
was found to heighten the diffusion potential barrier, while hole doping lowers
it. However, both kinds of dopings heighten the desorption potential barrier.
The underlying mechanism was revealed by investigating the effect of doping on
the bond strength of graphene and on the electron transfer and the coulomb
interaction between the hydrogen monomer and graphene. The kinetic properties
of H and D monomers on doped graphene layers during both the annealing process
(annealing time 300 s) and the constant-rate heating process (heating
rate 1.0 K/s) were simulated. Both electron and hole dopings were
found to generally increase the desorption temperatures of hydrogen monomers.
Electron doping was found to prevent the diffusion of hydrogen monomers, while
the hole doping enhances their diffusion. Macroscopic diffusion of hydrogen
monomers on graphene can be achieved when the doping-hole density reaches
cm. The magnetic moment and exchange splitting were
found to be reduced by both electron and hole dopings, which was explained by a
simple exchange model. The study in this report can further enhance the
understanding of the interaction between hydrogen and graphene and is expected
to be helpful in the design of hydrogenated-graphene-based devices.Comment: Submitte
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