391 research outputs found
High frequency variations of Helicobacter pylori isolates in individual hosts in a Chinese population
SummaryBackgroundColonization of individual hosts by multiple Helicobacter pylori genotypes may be one reason why this infection is persistent and difficult to eradicate.MethodsIn order to study the diversity of H. pylori in individuals, a modified randomly amplified polymorphic DNA (RAPD) method was applied using primary culture isolates instead of passaged cultures.ResultsThe results showed that variations in H. pylori were prevalent among individuals in the Chinese population, and the incidence of multiple colonization was 99.1% (115/116), significantly higher than in other reports. Moreover, the number of RAPD genotypes was found to be significantly associated with the process of disease development (p<0.05). Indeed, a trend for a higher number of RAPD genotypes within a single host (up to five genotypes) was observed as the disease developed or became more serious. After subculturing for three generations in our experiment, some genotypes present in the primary cultures were lost. The different genotypes in one patient may have originated from a single ancestral strain, as determined by analysis of six H. pylori housekeeping gene alleles, most of which were shown to be identical.ConclusionsThese results suggest that investigating isolates of the primary culture will better reflect the H. pylori diversity in individuals. Also, they indicate that continuous variation of one strain in the gastric microenvironment may be the main cause of H. pylori diversity in individuals in the Chinese population
Simple Memristive SPICE Macro-Models and Reconfigurability in Filter and Antenna
Simple current- and voltage-controlled memristive circuit macro-models using SPICE are proposed to capture the nonlinear hysteresis loop behaviors in this paper. Different current-voltage characteristics are investigated by applying sinusoidal-wave, triangular-wave and square-wave source, respectively. Furthermore, using finite-difference time-domain (FDTD) emulator incorporated with a SPICE circuit solver, the current- or voltage-controlled memristive SPICE model is embedded into a planar microwave bandstop filter (BSF) and an ultra-wideband (UWB) monopole antenna, which connects two ends of the half-wavelength open-loop resonator and two sides of the U-slot in the radiating patch, respectively. The reconfigurability of the BSF and antenna notched band can be achieved by switching the states of the memristor
Direct and Indirect Detection of Dark Matter in D6 Flavor Symmetric Model
We study a fermionic dark matter in a non-supersymmetric extension of the
standard model with a family symmetry based on D6xZ2xZ2. In our model, the
final state of the dark matter annihilation is determined to be e+ e- by the
flavor symmetry, which is consistent with the PAMELA result. At first, we show
that our dark matter mass should be within the range of 230 GeV - 750 GeV in
the WMAP analysis combined with mu to e gamma constraint. Moreover we
simultaneously explain the experiments of direct and indirect detection, by
simply adding a gauge and D6 singlet real scalar field. In the direct detection
experiments, we show that the lighter dark matter mass ~ 230 GeV and the
lighter standard model Higgs boson ~ 115 GeV is in favor of the observed bounds
reported by CDMS II and XENON100. In the indirect detection experiments, we
explain the positron excess reported by PAMELA through the Breit-Wigner
enhancement mechanism. We also show that our model is consistent with no
antiproton excess suggested by PAMELA.Comment: 20 pages, 9 figures, 2 tables, accepted version for publication in
European Physical Journal
Partial Wave Analysis of
BES data on are presented. The
contribution peaks strongly near threshold. It is fitted with a
broad resonance with mass MeV, width MeV. A broad resonance peaking at 2020 MeV is also required
with width MeV. There is further evidence for a component
peaking at 2.55 GeV. The non- contribution is close to phase
space; it peaks at 2.6 GeV and is very different from .Comment: 15 pages, 6 figures, 1 table, Submitted to PL
Plasma Wakefield Acceleration with a Modulated Proton Bunch
The plasma wakefield amplitudes which could be achieved via the modulation of
a long proton bunch are investigated. We find that in the limit of long bunches
compared to the plasma wavelength, the strength of the accelerating fields is
directly proportional to the number of particles in the drive bunch and
inversely proportional to the square of the transverse bunch size. The scaling
laws were tested and verified in detailed simulations using parameters of
existing proton accelerators, and large electric fields were achieved, reaching
1 GV/m for LHC bunches. Energy gains for test electrons beyond 6 TeV were found
in this case.Comment: 9 pages, 7 figure
The energy dependence of angular correlations inferred from mean- fluctuation scale dependence in heavy ion collisions at the SPS and RHIC
We present the first study of the energy dependence of angular
correlations inferred from event-wise mean transverse momentum
fluctuations in heavy ion collisions. We compare our large-acceptance
measurements at CM energies $\sqrt{s_{NN}} =$ 19.6, 62.4, 130 and 200 GeV to
SPS measurements at 12.3 and 17.3 GeV. $p_t$ angular correlation structure
suggests that the principal source of $p_t$ correlations and fluctuations is
minijets (minimum-bias parton fragments). We observe a dramatic increase in
correlations and fluctuations from SPS to RHIC energies, increasing linearly
with $\ln \sqrt{s_{NN}}$ from the onset of observable jet-related
fluctuations near 10 GeV.Comment: 10 pages, 4 figure
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
Effect of event selection on jetlike correlation measurement in d+Au collisions at sNN=200 GeV
AbstractDihadron correlations are analyzed in sNN=200 GeV d+Au collisions classified by forward charged particle multiplicity and zero-degree neutral energy in the Au-beam direction. It is found that the jetlike correlated yield increases with the event multiplicity. After taking into account this dependence, the non-jet contribution on the away side is minimal, leaving little room for a back-to-back ridge in these collisions
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