23,663 research outputs found
Spin-current injection and detection in strongly correlated organic conductor
Spin-current injection into an organic semiconductor
film induced by the spin
pumping from an yttrium iron garnet (YIG) film. When magnetization dynamics in
the YIG film is excited by ferromagnetic or spin-wave resonance, a voltage
signal was found to appear in the
film.
Magnetic-field-angle dependence measurements indicate that the voltage signal
is governed by the inverse spin Hall effect in
. We found that the
voltage signal in the /YIG
system is critically suppressed around 80 K, around which magnetic and/or glass
transitions occur, implying that the efficiency of the spin-current injection
is suppressed by fluctuations which critically enhanced near the transitions
Response of internal solitary waves to tropical storm Washi in the northwestern South China Sea
Based on in-situ time series data from an array of temperature sensors and
an acoustic Doppler current profiler on the continental shelf of the
northwestern South China Sea, a sequence of internal solitary waves (ISWs)
were observed during the passage of tropical storm Washi in the summer of
2005, which provided a unique opportunity to investigate the ISW response to
the tropical cyclone. The passing tropical storm is found to play an
important role in affecting the stratification structure of the water
column, and consequently leading to significant variability in the propagating features
of the ISWs, such as the polarity reversal and amplitude variations of the
waves. The response of the ISWs to Washi can be divided into two stages,
direct forcing by the strong wind (during the arrival of Washi) and remote
forcing via the near-inertial internal waves induced by the tropical storm
(after the passage of Washi). The field observations as well as a
theoretical analysis suggest that the variations of the ISWs closely
coincide with the changing stratification structure and shear currents in
accompanied by the typhoon wind and near-inertial waves. This study presents
the first observations and analysis of the ISW response to the tropical
cyclone in the South China Sea
Linear scaling calculation of maximally-localized Wannier functions with atomic basis set
We have developed a linear scaling algorithm for calculating
maximally-localized Wannier functions (MLWFs) using atomic orbital basis. An
O(N) ground state calculation is carried out to get the density matrix (DM).
Through a projection of the DM onto atomic orbitals and a subsequent O(N)
orthogonalization, we obtain initial orthogonal localized orbitals. These
orbitals can be maximally localized in linear scaling by simple Jacobi sweeps.
Our O(N) method is validated by applying it to water molecule and wurtzite ZnO.
The linear scaling behavior of the new method is demonstrated by computing the
MLWFs of boron nitride nanotubes.Comment: J. Chem. Phys. in press (2006
Coherent control of plasma dynamics
Coherent control of a system involves steering an interaction to a final
coherent state by controlling the phase of an applied field. Plasmas support
coherent wave structures that can be generated by intense laser fields. Here,
we demonstrate the coherent control of plasma dynamics in a laser wakefield
electron acceleration experiment. A genetic algorithm is implemented using a
deformable mirror with the electron beam signal as feedback, which allows a
heuristic search for the optimal wavefront under laser-plasma conditions that
is not known a priori. We are able to improve both the electron beam charge and
angular distribution by an order of magnitude. These improvements do not simply
correlate with having the `best' focal spot, since the highest quality vacuum
focal spot produces a greatly inferior electron beam, but instead correspond to
the particular laser phase that steers the plasma wave to a final state with
optimal accelerating fields
Antiviral treatment alters the frequency of activating and inhibitory receptor-expressing natural killer cells in chronic Hepatitis B virus infected patients
Natural killer (NK) cells play a critical role in innate antiviral immunity, but little is known about the impact of antiviral therapy on the frequency of NK cell subsets. To this aim, we performed this longitudinal study to examine the dynamic changes of the frequency of different subsets of NK cells in CHB patients after initiation of tenofovir or adefovir therapy. We found that NK cell numbers and subset distribution differ between CHB patients and normal subjects; furthermore, the association was found between ALT level and CD158b+ NK cell in HBV patients. In tenofovir group, the frequency of NK cells increased during the treatment accompanied by downregulated expression of NKG2A and KIR2DL3. In adefovir group, NK cell numbers did not differ during the treatment, but also accompanied by downregulated expression of NKG2A and KIR2DL3. Our results demonstrate that treatment with tenofovir leads to viral load reduction, and correlated with NK cell frequencies in peripheral blood of chronic hepatitis B virus infection. In addition, treatments with both tenofovir and adefovir in chronic HBV infected patients induce a decrease of the frequency of inhibitory receptor+ NK cells, which may account for the partial restoration of the function of NK cells in peripheral blood following treatment
A random amplified polymorphic DNA (RAPD) molecular marker linked to late-bolting gene in pak-choi (Brassica campestris ssp. chinensis Makino L.)
Bulked segregant analysis (BSA) and random amplified polymorphic DNA (RAPD) methods were used to analyze F2 individuals of P-27 × P-28 to screen and characterize the molecular marker linked to latebolting gene in pak-choi (Brassica campestris ssp. chinensis Makino L.). A total of 200 random primers were used for RAPD analysis. One RAPD marker S265750 was identified to be co-segregating with the late-bolting gene, and the genetic distances between S265750 and late-bolting gene was 3.14 cM. The results of the study can be seen as a starting point for future researches on the pak-choi bolting gene mapping and molecular marker assisted breeding.Key words: Pak-choi, late bolting, random amplified polymorphic DNA (RAPD), bulked segregant analysis (BSA)
Trajectory optimization of unmanned aerial vehicle in dynamic soaring
An aircraft can extract energy from a gradient wind field by dynamic soaring. The paper presents trajectory optimization of an unmanned aerial vehicle for dynamic soaring by numerical analysis and validates the theoretical work through flight test. The collocation approach is used to convert the trajectory optimization problem into parameters optimization. The control and state parameters include lift coefficient, bank angle, positions, flight path angle, heading angle, and airspeed, which are obtained from the parameter optimization software. To validate the results of numerical simulation, the dynamic soaring experiment is also performed and experimental data are analyzed. This research work shows that the unmanned aerial vehicle can gain enough flight energy from the gradient wind field by following an optimal dynamic soaring trajectory. Meanwhile, the variation of flight path angle, heading angle, and airspeed has a significant influence on the energy transform. The solution can provide theoretical guide to unmanned aerial vehicles for extracting maximum energy from gradient wind fields. </jats:p
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