2,230 research outputs found
Practical Decoy State for Quantum Key Distribution
Decoy states have recently been proposed as a useful method for substantially
improving the performance of quantum key distribution. Here, we present a
general theory of the decoy state protocol based on only two decoy states and
one signal state. We perform optimization on the choice of intensities of the
two decoy states and the signal state. Our result shows that a decoy state
protocol with only two types of decoy states--the vacuum and a weak decoy
state--asymptotically approaches the theoretical limit of the most general type
of decoy state protocols (with an infinite number of decoy states). We also
present a one-decoy-state protocol. Moreover, we provide estimations on the
effects of statistical fluctuations and suggest that, even for long distance
(larger than 100km) QKD, our two-decoy-state protocol can be implemented with
only a few hours of experimental data. In conclusion, decoy state quantum key
distribution is highly practical.Comment: 31 pages. 6 figures. Preprint forma
An All-Recombinant Protein-Based Culture System Specifically Identifies Hematopoietic Stem Cell Maintenance Factors.
Hematopoietic stem cells (HSCs) are considered one of the most promising therapeutic targets for the treatment of various blood disorders. However, due to difficulties in establishing stable maintenance and expansion of HSCs in vitro, their insufficient supply is a major constraint to transplantation studies. To solve these problems we have developed a fully defined, all-recombinant protein-based culture system. Through this system, we have identified hemopexin (HPX) and interleukin-1α as responsible for HSC maintenance in vitro. Subsequent molecular analysis revealed that HPX reduces intracellular reactive oxygen species levels within cultured HSCs. Furthermore, bone marrow immunostaining and 3D immunohistochemistry revealed that HPX is expressed in non-myelinating Schwann cells, known HSC niche constituents. These results highlight the utility of this fully defined all-recombinant protein-based culture system for reproducible in vitro HSC culture and its potential to contribute to the identification of factors responsible for in vitro maintenance, expansion, and differentiation of stem cell populations
A projection method for approximating fixed points of quasinonexpansive mappings in Hadamard spaces
Theory of magnetoelectric resonance in two-dimensional antiferromagnet via spin-dependent metal-ligand hybridization mechanism
We investigate magnetic excitations in an Heisenberg model
representing two-dimensional antiferromagnet . In
terahertz absorption experiment of the compound, Goldstone mode as well as
novel magnetic excitations, conventional magnetic resonance at 2 meV and both
electric- and magnetic-active excitation at 4 meV, have been observed. By
introducing a hard uniaxial anisotropy term , three modes can
be explained naturally. We also indicate that, via the spin-dependent
metal-ligand hybridization mechanism, the 4 meV excitation is an
electric-active mode through the coupling between spin and electric-dipole.
Moreover, at 4 meV excitation, an interference between magnetic and electric
responses emerges as a cross correlated effect. Such cross correlation effects
explain the non-reciprocal linear directional dichroism observed in .Comment: 5 pages, 3 figure
Non-commutative geometry of 4-dimensional quantum Hall droplet
We develop the description of non-commutative geometry of the 4-dimensional
quantum Hall fluid's theory proposed recently by Zhang and Hu. The
non-commutative structure of fuzzy appears naturally in this theory.
The fuzzy monopole harmonics, which are the essential elements in this
non-commutative geometry, are explicitly constructed and their obeying the
matrix algebra is obtained. This matrix algebra is associative. We also propose
a fusion scheme of the fuzzy monopole harmonics of the coupling system from
those of the subsystems, and determine the fusion rule in such fusion scheme.
By products, we provide some essential ingredients of the theory of SO(5)
angular momentum. In particular, the explicit expression of the coupling
coefficients, in the theory of SO(5) angular momentum, are given. It is
discussed that some possible applications of our results to the 4-dimensional
quantum Hall system and the matrix brane construction in M-theory.Comment: latex 22 pages, no figures. some references added. some results are
clarifie
Comments on Heterotic Flux Compactifications
In heterotic flux compactification with supersymmetry, three different
connections with torsion appear naturally, all in the form .
Supersymmetry condition carries , the Dirac operator has , and
higher order term in the effective action involves . With a view toward
the gauge sector, we explore the geometry with such torsions. After reviewing
the supersymmetry constraints and finding a relation between the scalar
curvature and the flux, we derive the squared form of the zero mode equations
for gauge fermions. With \d H=0, the operator has a positive potential term,
and the mass of the unbroken gauge sector appears formally positive definite.
However, this apparent contradiction is avoided by a no-go theorem that the
compactification with and \d H=0 is necessarily singular, and the
formal positivity is invalid. With \d H\neq 0, smooth compactification
becomes possible. We show that, at least near smooth supersymmetric solution,
the size of should be comparable to that of \d H and the consistent
truncation of action has to keep term. A warp factor equation of
motion is rewritten with contribution included precisely, and
some limits are considered.Comment: 31 pages, a numerical factor correcte
A Randomized Pilot Study of Atractylenolide I on Gastric Cancer Cachexia Patients
We determined the therapeutic efficacy of atractylenolide I (ATR), extracted from largehead atractylodes rhizome, in managing gastric cancer cachexia (GCC), and interpreted its probable pharmacological mechanism via investigating tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6) and proteolysis-inducing factor (PIF). This was a randomized but not-blinded pilot. The study group (n = 11) received 1.32 g per day of atractylenolide I (ATR) and the control group (n = 11) received 3.6 g per day of fish-oil-enriched nutritional supplementation (FOE) for 7 weeks. Conservative therapy was similar in both groups. Clinical [appetite, body weight, mid-arm muscle circumference (MAMC), Karnofsky performance status (KPS) status], biomarker (TNF-α, IL-1, IL-6 and PIF) were evaluated in the basal state, at the third and seventh weeks. To analyze changes of cytokines, an immumohistochemistry technique was adopted. Base line characteristics were similar in both groups. Effects on MAMC and body weight increase, TNF-α increase and IL-1 decreases of serum level were significant in both groups (P < 0.05). ATR was significantly more effective than FOE in improving appetite and KPS status, and decreasing PIF positive rate (P < 0.05). Slight nausea (3/11) and dry mouth (1/11) were shown in intervention groups but did not interrupt treatment. These preliminary findings suggest that ATR might be beneficial in alleviating symptoms, in modulating cytokine and in inhibiting PIF proteolysis of gastric cancer cachexia. Further research using a randomized controlled design is necessary to confirm these pilot study findings
Cathodoluminescene study of Mg implanted GaN: the impact of dislocation on Mg diffusion
Magnesium (Mg) ion implanted homoepitaxial GaN layers is investigated by cathodoluminescence (CL) and secondary ion mass spectrometry (SIMS). The impact of dislocations on Mg diffusion is clarified by CL monitoring the Mg-related donor-acceptor pair (DAP) emission on novel angle cutting specimen. CL results suggest that: (1) there exist high concentration of nonradiative defects in a Mg implanted layer; and (2) Mg shows pipe diffusion along threading dislocations throughout epilayer to substrate. To achieve successful Mg doping by ion implantation, it is necessary to suppress the formation of a dead region in the Mg implanted layer and the pipe diffusion along threading dislocations
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