16,408 research outputs found
Improving the security of quantum direct communication with authentication
Two protocols of quantum direct communication with authentication [Phys. Rev.
A {\bf 73}, 042305 (2006)] are recently proposed by Lee, Lim and Yang. In this
paper we will show that in the two protocols the authenticator Trent should be
prevented from knowing the secret message of communication. The first protocol
can be eavesdropped by Trent using the the intercept-measure-resend attack,
while the second protocol can be eavesdropped by Trent using single-qubit
measurement. To fix these leaks, I revise the original versions of the
protocols by using the Pauli-Z operation instead of the original
bit-flip operation . As a consequence, the protocol securities are improved.Comment: Any suggestion,comment or help is welcome
On Random Walks with a General Moving Barrier
Random walks with a general, nonlinear barrier have found recent applications
ranging from reionization topology to refinements in the excursion set theory
of halos. Here, we derive the first-crossing distribution of random walks with
a moving barrier of an arbitrary shape. Such a distribution is shown to satisfy
an integral equation that can be solved by a simple matrix inversion, without
the need for Monte Carlo simulations, making this useful for exploring a large
parameter space. We discuss examples in which common analytic approximations
fail, a failure which can be remedied using the method described here.Comment: 6 pages, 7 figures, submitted to Ap
Evidence for a new resonance with in the old data of reaction
Distinctive patterns are predicted by quenched quark models and unquenched
quark models for the lowest SU(3) baryon nonet with spin parity .
While the quenched quark models predict the lowest resonance
to be above 1600 MeV, the unquenched quark models predict it to be around
energy. Here we re-examine some old data of the \kp \to \la
reaction and find that besides the well established with
, there is indeed some evidence for the possible existence of a new
resonance with around the same mass but with broader
decay width. Higher statistic data on relevant reactions are needed to clarify
the situation.Comment: 7 pages, 4 figure
Negative reflections of electromagnetic waves in chiral media
We investigate the reflection properties of electromagnetic/optical waves in
isotropic chiral media. When the chiral parameter is strong enough, we show
that an unusual \emph{negative reflection} occurs at the interface of the
chiral medium and a perfectly conducting plane, where the incident wave and one
of reflected eigenwaves lie in the same side of the boundary normal. Using such
a property, we further demonstrate that such a conducting plane can be used for
focusing in the strong chiral medium. The related equations under paraxial
optics approximation are deduced. In a special case of chiral medium, the
chiral nihility, one of the bi-reflections disappears and only single reflected
eigenwave exists, which goes exactly opposite to the incident wave. Hence the
incident and reflected electric fields will cancel each other to yield a zero
total electric field. In another word, any electromagnetic waves entering the
chiral nihility with perfectly conducting plane will disappear.Comment: 5 pages, 5 figure
Associated strangeness production in the pp to pK^+K^-p and pp to pK^+ pi^0 Sigma^0 reactions
The total and differential cross sections for associated strangeness
production in the and reactions
have been studied in a unified approach using an effective Lagrangian model. It
is assumed that both the and final states originate from
the decay of the resonance which was formed in the production
chain . The available experimental data
are well reproduced, especially the ratio of the two total cross sections,
which is much less sensitive to the particular model of the entrance channel.
The significant coupling of the resonance to is
further evidence for large components in the quark wave function of
the resonance.Comment: Published in Phys. Rev.
Biochemical, haematological and histopathological studies of extract of Ageratum conyzoides L. in Sprague Dawley rats
This study was conducted to evaluate the safety potential of the leaf extract of Ageratum conyzoides Linnaeus in Sprague Dawley (SD) rats using biochemical, haematological and histological indices of toxicity. Four groups of seven male SD rats per group were used for the study. To group A was administered 0.25% CMC-Na/ kg body weight and was used as the control group, while groups B, C and D were respectively administered with 500, 1000 and 1500 mg/kg body weight of the ethanolic leaf extract of A. conyzoides by gastric intubation for 14 days. Animals were subsequently anaesthetized, blood samples were collected for biochemical and haematological assays; organs were isolated and weighed, while the liver, kidney and spleen were processed for histopathological studies. Aspartate
amino transferase, lactate dehydrogenase, creatine kinase and alkaline phosphatase were significantly (p < 0.05) reduced in the groups treated with 1000 and 1500 mg/kg body weight of the extract. Furthermore, there was a significant (p < 0.05) elevation in white blood cell count, mean platelet volume and % platelet distribution width. Histopathological studies indicated various degrees of hepatocellular necrosis in all the treated groups accompanied by significant increases in the weight of liver and spleen. The results showed that the ethanolic leaf extract of A. conyzoides significantly alters the
biomarkers of cardiac and skeletal muscle disorders, and higher doses could induce liver cell injury
Possible under the peak in photoproduction
The LEPS collaboration has recently reported a measurement of the reaction
with linearly polarized photon beam at
resonance region. The observed beam asymmetry is sizably negative at
, in contrast to the presented theoretical
prediction. In this paper, we calculate this process in the framework of the
effective Lagrangian approach. By including a newly proposed
state with mass around 1380~MeV, the experimental
data for both and experiments can be well reproduced. It
is found that the and/or the contact term may play
important role and deserve further investigation.Comment: modified version to be published at Phys. Rev.
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