4,339 research outputs found
Comprehensive Characterization of the Transmitted/Founder env Genes From a Single MSM Cohort in China
Background: The men having sex with men (MSM) population has become one of the major risk groups for HIV-1 infection in China. However, the epidemiological patterns, function of the env genes, and autologous and heterologous neutralization activity in the same MSM population have not been systematically characterized. Methods: The env gene sequences were obtained by the single genome amplification. The time to the most recent common ancestor was estimated for each genotype using the Bayesian Markov Chain Monte Carlo approach. Coreceptor usage was determined in NP-2 cells. Neutralization was analyzed using Env pseudoviruses in TZM-bl cells. Results: We have obtained 547 full-length env gene sequences by single genome amplification from 30 acute/early HIV-1–infected individuals in the Beijing MSM cohort. Three genotypes (subtype B, CRF01_AE, and CRF07_BC) were identified and 20% of the individuals were infected with multiple transmitted/founder (T/F) viruses. The tight clusters of the MSM sequences regardless of geographic origins indicated nearly exclusive transmission within the MSM population and limited number of introductions. The time to the most recent common ancestor for each genotype was 10–15 years after each was first introduced in China. Disparate preferences for coreceptor usages among 3 genotypes might lead to the changes in percentage of different genotypes in the MSM population over time. The genotype-matched and genotype-mismatched neutralization activity varied among the 3 genotypes. Conclusions: The identification of unique characteristics for transmission, coreceptor usage, neutralization profile, and epidemic patterns of HIV-1 is critical for the better understanding of transmission mechanisms, development of preventive strategies, and evaluation of vaccine efficacy in the MSM population in China
A novel configuration model for random graphs with given degree sequence
Recently, random graphs in which vertices are characterized by hidden
variables controlling the establishment of edges between pairs of vertices have
attracted much attention. Here, we present a specific realization of a class of
random network models in which the connection probability between two vertices
(i,j) is a specific function of degrees ki and kj. In the framework of the
configuration model of random graphs, we find analytical expressions for the
degree correlation and clustering as a function of the variance of the desired
degree distribution. The expressions obtained are checked by means of numerical
simulations. Possible applications of our model are discussed.Comment: 7 pages, 3 figure
Recommended from our members
Elucidating the Limit of Li Insertion into the Spinel Li4Ti5O12
In this work, we show that the well-known lithium-ion anode material, Li4Ti5O12, exhibits exceptionally high initial capacity of 310 mAh g-1 when it is discharged to 0.01 V. It maintains a reversible capacity of 230 mAh g-1, far exceeding the "theoretical" capacity of 175 mAh g-1 when this anode is lithiated to the composition Li7Ti5O12. Neutron diffraction analyses identify that additional Li reversibly enters into the Li7Ti5O12 to form Li8Ti5O12. density functional theory (DFT) calculations reveal the average potentials of the Li4Ti5O12 to Li7Ti5O12 step and the Li7Ti5O12 to Li8Ti5O12 step are 1.57 and 0.19 V, respectively, which are in excellent agreement with experimental results. Transmission electron microscopy (TEM) studies confirm that the irreversible capacity of Li4Ti5O12 during its first cycle originates from the formation of a solid electrolyte interface (SEI) layer. This work clarifies the fundamental lithiation mechanism of the Li4Ti5O12, when lithiated to 0.01 V vs Li
High performance perovskite solar cells using Cu9S5 supraparticles incorporated hole transport layers
Statefinder diagnosis in a non-flat universe and the holographic model of dark energy
In this paper, we study the holographic dark energy model in non-flat
universe from the statefinder viewpoint. We plot the evolutionary trajectories
of the holographic dark energy model for different values of the parameter
as well as for different contributions of spatial curvature, in the statefinder
parameter-planes. The statefinder diagrams characterize the properties of the
holographic dark energy and show the discrimination between this scenario and
other dark energy models. As we show, the contributions of the spatial
curvature in the model can be diagnosed out explicitly by the statefinder
diagrams. Furthermore, we also investigate the holographic dark energy model in
the plane, which can provide us with a useful dynamical diagnosis
complement to the statefinder geometrical diagnosis.Comment: 16 pages, 4 figures; final versio
On Gauge Theory and Topological String in Nekrasov-Shatashvili Limit
We study the Nekrasov-Shatashvili limit of the N=2 supersymmetric gauge
theory and topological string theory on certain local toric Calabi-Yau
manifolds. In this limit one of the two deformation parameters \epsilon_{1,2}
of the Omega background is set to zero and we study the perturbative expansion
of the topological amplitudes around the remaining parameter. We derive
differential equations from Seiberg-Witten curves and mirror geometries, which
determine the higher genus topological amplitudes up to a constant. We show
that the higher genus formulae previously obtained from holomorphic anomaly
equations and boundary conditions satisfy these differential equations. We also
provide a derivation of the holomorphic anomaly equations in the
Nekrasov-Shatashvili limit from these differential equations.Comment: 41 pages, no figure. v2: references adde
Jet Quenching in the Opposite Direction of a Tagged Photon in High-Energy Heavy-Ion Collisions
We point out that events associated with large direct photons in
high-energy heavy-ion collisions can be used to study jet energy loss in dense
matter. In such events, the spectrum of charged hadrons from jet
fragmentation in the opposite direction of the tagged photon is estimated to be
well above the background which can be reliably subtracted at moderately large
. We demonstrate that comparison between the extracted fragmentation
function in and collisions can be used to determine the jet energy
loss and the interaction mean-free-path in the dense matter produced in
high-energy heavy-ion collisions.Comment: 4 pages in RevTex twocolumn with embedded psfigure
Statefinder diagnostic for holographic dark energy model
In this paper we study the holographic dark energy model proposed by Li from
the statefinder viewpoint. We plot the evolutionary trajectories of the model
with in the statefinder parameter-planes. The statefinder diagrams
characterize the properties of the holographic dark energy and show the
discrimination between this scenario and other dark energy models. We also
perform a statefinder diagnostic to the holographic dark energy model in cases
of different which given by three fits to observational data. The result
indicates that from the statefinder viewpoint plays a significant role in
this model and should thus be determined seriously by future high precision
experiments.Comment: 13 pages, 3 figure
Inflationary universe in loop quantum cosmology
Loop quantum cosmology provides a nice solution of avoiding the big bang
singularity through a big bounce mechanism in the high energy region. In loop
quantum cosmology an inflationary universe is emergent after the big bounce, no
matter what matter component is filled in the universe. A super-inflation phase
without phantom matter will appear in a certain way in the initial stage after
the bounce; then the universe will undergo a normal inflation stage. We discuss
the condition of inflation in detail in this framework. Also, for slow-roll
inflation, we expect the imprint from the effects of the loop quantum cosmology
should be left in the primordial perturbation power spectrum. However, we show
that this imprint is too weak to be observed.Comment: 21 pages, 4 figures; accepted for publication in JCA
- …