10,868 research outputs found
The inertia of weighted unicyclic graphs
Let be a weighted graph. The \textit{inertia} of is the triple
, where
are the number of the positive, negative and zero
eigenvalues of the adjacency matrix of including their
multiplicities, respectively. , is called the
\textit{positive, negative index of inertia} of , respectively. In this
paper we present a lower bound for the positive, negative index of weighted
unicyclic graphs of order with fixed girth and characterize all weighted
unicyclic graphs attaining this lower bound. Moreover, we characterize the
weighted unicyclic graphs of order with two positive, two negative and at
least zero eigenvalues, respectively.Comment: 23 pages, 8figure
Nuclear stopping and sideward-flow correlation from 0.35A to 200A GeV
The correlation between the nuclear stopping and the scale invariant nucleon
sideward flow at energies ranging from those available at the GSI heavy ion
synchrotron (SIS) to those at the CERN Super Proton Synchrotron (SPS) is
studied within ultrarelativistic quantum molecular dynamics (UrQMD). The
universal behavior of the two experimental observables for various colliding
systems and scale impact parameters are found to be highly correlated with each
other. As there is no phase transition mechanism involved in the UrQMD, the
correlation may be broken down by the sudden change of the bulk properties of
the nuclear matter, such as the formation of quark-gluon plasma (QGP), which
can be employed as a QGP phase transition signal in high-energy heavy ion
collisions. Furthermore, we also point out that the appearance of a breakdown
of the correlation may be a powerful tool for searching for the critical point
on the QCD phase diagram.Comment: 5 pages, 4 figure
The Discussion of the Virtual High Drug Price
This article analyzes the situation of the medicine price in our medical industry, and the reason for the virtual high price of the medicine, including government regulation and medical insurance system defects. Then puts forward corresponding measures to solve the problem
PEDF in Diabetic Retinopathy: A Protective Effect of Oxidative Stress
Diabetic retinopathy (DR) is a major cause of blindness in working age adults, and oxidative stress plays a vital role in the pathogenesis of DR. Pigment-epithelium-derived factor (PEDF), a multifunctional protein, has shown to inhibit the development of DR by accumulating evidence. This paper highlights the current understanding of probable mechanism about how PEDF blocks the deterioration of DR through its antioxidative properties and application prospects of PEDF as a novel therapeutic target in DR. Gene therapy of PEDF is becoming more and more acceptable and will widely be applied to the actual treatment in the near future
Valley Carrier Dynamics in Monolayer Molybdenum Disulphide from Helicity Resolved Ultrafast Pump-probe Spectroscopy
We investigate the valley related carrier dynamics in monolayer MoS2 using
helicity resolved non-degenerate ultrafast pump-probe spectroscopy at the
vicinity of the high-symmetry K point under the temperature down to 78 K.
Monolayer MoS2 shows remarkable transient reflection signals, in stark contrast
to bilayer and bulk MoS2 due to the enhancement of many-body effect at reduced
dimensionality. The helicity resolved ultrafast time-resolved result shows that
the valley polarization is preserved for only several ps before scattering
process makes it undistinguishable. We suggest that the dynamical degradation
of valley polarization is attributable primarily to the exciton trapping by
defect states in the exfoliated MoS2 samples. Our experiment and a
tight-binding model analysis also show that the perfect valley CD selectivity
is fairly robust against disorder at the K point, but quickly decays from the
high-symmetry point in the momentum space in the presence of disorder.Comment: 15 pages,Accepted by ACS Nan
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