799 research outputs found
First Order Sea Clutter Cross Section for HF Hybrid Sky-Surface Wave Radar
This paper presents a modified method to simulate the first order sea clutter cross section for high frequency (HF) hybrid sky-surface wave radar, based on the existent model applied in the bistatic HF surface wave radar. The modification focuses on the derivation of Bragg scattering frequency and the ionosphere dispersive impact on the clutter resolution cell. Meanwhile, an analytic expression to calculate the dispersive transfer function is derived on condition that the ionosphere is spherical stratified. Simulation results explicate the variance of the cross section after taking account of the influence triggered by the actual clutter resolution cell, and the spectral width of the first order sea clutter is defined so as to compare the difference. Eventually, experiment results are present to verify the rationality and validity of the proposed method
Space-time Characteristics and Experimental Analysis of Broadening First-order Sea Clutter in HF Hybrid Sky-surface Wave Radar
In high frequency (HF) hybrid sky-surface wave radar, the first-order sea clutter broadening is very complex and serious under the influence of ionosphere and bistatic angle, which affects the detection of ship target. This paper analyzes the space-time characteristics based on the HF sky-surface wave experimental system. We first introduce the basic structure, working principle and position principle based on our experimental system. Also analyzed is the influence of ionosphere and bistatic angle on the space-time coupling characteristics of broadening first-order sea clutter and the performance of space-time adaptive processing (STAP). Finally, the results of theoretic analysis are examined with the experimental data. Simulation results show that the results of experiment consist with that of theoretic analysis
Plasmid encoding matrix protein of vesicular stomatitis viruses as an antitumor agent inhibiting rat glioma growth in situ
Aim: Oncolytic effect of vesicular stomatitis virus (VSV) has been proved previously. Aim of the study is to investigate glioma inhibition effect of Matrix (M) protein of VSV in situ. Materials and Methods: A recombinant plasmid encoding VSV M protein (PM) was genetically engineered, and then transfected into cultured C6 gliomas cells in vitro. C6 transfected with Liposome-encapsulated PM (LEPM) was implanted intracranially for tumorigenicity study. In treatment experiment, rats were sequentially established intracranial gliomas with wild-typed C6 cells, and accepted LEPM injection intravenously. Possible mechanism of M protein was studied by using Hoechst staining, PI-stained flow cytometric analysis, TUNEL staining and CD31 staining. Results: M protein can induce generous gliomas lysis in vitro. None of the rats implanted with LEPM-treated cells developed any significant tumors, whereas all rats in control group developed tumors. In treatment experiment, smaller tumor volume and prolonged survival time was found in the LEPM-treated group. Histological studies revealed that possible mechanism were apoptosis and anti-angiogenesis. Conclusion: VSV-M protein can inhibit gliomas growth in vitro and in situ, which indicates such a potential novel biotherapeutic strategy for glioma treatment.Π¦Π΅Π»Ρ: ΠΈΠ·ΡΡΠΈΡΡ ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΡ ΠΌΠ°ΡΡΠΈΠΊΡΠ½ΠΎΠ³ΠΎ ΠΏΡΠΎΡΠ΅ΠΈΠ½Π° (Π ΠΏΡΠΎΡΠ΅ΠΈΠ½Π°) Π²ΠΈΡΡΡΠ° Π²Π΅Π·ΠΈΠΊΡΠ»ΡΡΠ½ΠΎΠ³ΠΎ ΡΡΠΎΠΌΠ°ΡΠΈΡΠ° (ΠΠΠ‘) ΡΠ³Π½Π΅ΡΠ°ΡΡ ΡΠΎΡΡ Π³Π»ΠΈΠΎΠΌΡ
in situ. ΠΠ°ΡΠ΅ΡΠΈΠ°Π»Ρ ΠΈ ΠΌΠ΅ΡΠΎΠ΄Ρ: ΡΠΊΠΎΠ½ΡΡΡΡΠΈΡΠΎΠ²Π°Π½Π° ΡΠ΅ΠΊΠΎΠΌΠ±ΠΈΠ½Π°Π½ΡΠ½Π°Ρ ΠΏΠ»Π°Π·ΠΌΠΈΠ΄Π°, ΠΊΠΎΠ΄ΠΈΡΡΡΡΠ°Ρ Π ΠΏΡΠΎΡΠ΅ΠΈΠ½ ΠΠΠ‘, ΠΊΠΎΡΠΎΡΠ°Ρ Π·Π°ΡΠ΅ΠΌ Π±ΡΠ»Π°
ΡΡΠ°Π½ΡΡΠ΅ΡΠΈΡΠΎΠ²Π°Π½Π° Π² ΠΊΡΠ»ΡΡΠΈΠ²ΠΈΡΠΎΠ²Π°Π½Π½ΡΠ΅ ΠΊΠ»Π΅ΡΠΊΠΈ Π³Π»ΠΈΠΎΠΌΡ Π‘6 in. ΠΠ»Π΅ΡΠΊΠΈ Π³Π»ΠΈΠΎΠΌΡ Π‘6, ΡΡΠ°Π½ΡΡΠ΅ΡΠΈΡΠΎΠ²Π°Π½Π½ΡΠ΅ ΠΈΠ½ΠΊΠ°ΠΏΡΡΠ»ΠΈΡΠΎΠ²Π°Π½Π½ΡΠΌ
Π² Π»ΠΈΠΏΠΎΡΠΎΠΌΡ Π ΠΏΡΠΎΡΠ΅ΠΈΠ½ΠΎΠΌ (ΠΠΠΠ), ΠΈΠΌΠΏΠ»Π°Π½ΡΠΈΡΠΎΠ²Π°Π»ΠΈ ΠΈΠ½ΡΡΠ°ΠΊΡΠ°Π½ΠΈΠ°Π»ΡΠ½ΠΎ Π΄Π»Ρ ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ ΡΡΠΌΠΎΡΠΎΠ³Π΅Π½Π½ΠΎΡΡΠΈ. Π ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ΅ ΠΊΡΡΡΠ°ΠΌ
Ρ ΡΡΠ°Π½ΡΠΏΠ»Π°Π½ΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΉ ΠΈΠ½ΡΡΠ°ΠΊΡΠ°Π½ΠΈΠ°Π»ΡΠ½ΠΎ Π³Π»ΠΈΠΎΠΌΠΎΠΉ Π‘6 (ΠΈΡΡ
ΠΎΠ΄Π½ΡΠΉ ΡΡΠ°ΠΌΠΌ) Π²Π½ΡΡΡΠΈΠ²Π΅Π½Π½ΠΎ Π²Π²ΠΎΠ΄ΠΈΠ»ΠΈ ΠΠΠΠ. ΠΠΏΠΎΠΏΡΠΎΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ Π΄Π΅ΠΉΡΡΠ²ΠΈΠ΅
Π ΠΏΡΠΎΡΠ΅ΠΈΠ½Π° Π½Π° ΠΎΠΏΡΡ
ΠΎΠ»Π΅Π²ΡΠ΅ ΠΊΠ»Π΅ΡΠΊΠΈ ΠΈΠ·ΡΡΠ°Π»ΠΈ Ρ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ΠΌ ΡΠ»ΡΠΎΡΠ΅ΡΡΠ΅Π½ΡΠ΅Π½ΡΠ½ΠΎΠΉ ΠΌΠΈΠΊΡΠΎΡΠΊΠΎΠΏΠΈΠΈ (ΠΎΠΊΡΠ°ΡΠΈΠ²Π°Π½ΠΈΠ΅ ΠΏΠΎ Π₯Π΅Ρ
ΡΡΡ),
ΠΏΡΠΎΡΠΎΡΠ½ΠΎΠΉ ΡΠΈΡΠΎΠΌΠ΅ΡΡΠΈΠΈ (ΠΎΠΊΡΠ°ΡΠΈΠ²Π°Π½ΠΈΠ΅ ΠΏΡΠΎΠΏΠΈΠ΄ΠΈΡΠΌΠΎΠΌ ΠΉΠΎΠ΄ΠΈΠ΄ΠΎΠΌ), TUNEL Π²Π°ΡΠΊΡΠ»ΡΡΠΈΠ·Π°ΡΠΈΡ ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ ΠΎΡΠ΅Π½ΠΈΠ²Π°Π»ΠΈ Π³ΠΈΡΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈ ΠΈ Π²Π°ΡΠΊΡΠ»ΡΡΠΈΠ·Π°ΡΠΈΡ ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ ΠΎΡΠ΅Π½ΠΈΠ²Π°Π»ΠΈ Π³ΠΈΡΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈ ΠΈ
ΠΈΠΌΠΌΡΠ½ΠΎΠ³ΠΈΡΡΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈ Ρ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ΠΌ Π°Π½ΡΠΈ-CD31 ΠΌΠΎΠ½ΠΎΠΊΠ»ΠΎΠ½Π°Π»ΡΠ½ΡΡ
Π°Π½ΡΠΈΡΠ΅Π». 31 ΠΌΠΎΠ½ΠΎΠΊΠ»ΠΎΠ½Π°Π»ΡΠ½ΡΡ
Π°Π½ΡΠΈΡΠ΅Π». 31 ΠΌΠΎΠ½ΠΎΠΊΠ»ΠΎΠ½Π°Π»ΡΠ½ΡΡ
Π°Π½ΡΠΈΡΠ΅Π». Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ: Π ΠΏΡΠΎΡΠ΅ΠΈΠ½ ΠΌΠΎΠΆΠ΅Ρ ΠΈΠ½Π΄ΡΡΠΈΡΠΎΠ²Π°ΡΡ
Π»ΠΈΠ·ΠΈΡ ΠΊΠ»Π΅ΡΠΎΠΊ Π³Π»ΠΈΠΎΠΌΡ in. ΠΠΈ Ρ ΠΎΠ΄Π½ΠΎΠ³ΠΎ ΠΆΠΈΠ²ΠΎΡΠ½ΠΎΠ³ΠΎ Ρ ΡΡΠ°Π½ΡΠΏΠ»Π°Π½ΡΠΈΡΠΎΠ²Π°Π½Π½ΡΠΌΠΈ ΠΊΠ»Π΅ΡΠΊΠ°ΠΌΠΈ Π³Π»ΠΈΠΎΠΌΡ, ΠΎΠ±ΡΠ°Π±ΠΎΡΠ°Π½Π½ΡΠΌΠΈ ΠΠΠΠ,
Π½Π΅ Π²ΠΎΠ·Π½ΠΈΠΊΠ°Π»ΠΈ ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎΠ³ΠΎ ΡΠ°Π·ΠΌΠ΅ΡΠ°, ΡΠΎΠ³Π΄Π° ΠΊΠ°ΠΊ Ρ Π²ΡΠ΅Ρ
ΠΊΡΡΡ ΠΈΠ· ΠΊΠΎΠ½ΡΡΠΎΠ»ΡΠ½ΠΎΠΉ Π³ΡΡΠΏΠΏΡ ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ ΡΠ°Π·Π²ΠΈΠ²Π°Π»ΠΈΡΡ. Π Π³ΡΡΠΏΠΏΠ΅
ΠΆΠΈΠ²ΠΎΡΠ½ΡΡ
, ΠΊΠΎΡΠΎΡΡΠΌ Π²Π²ΠΎΠ΄ΠΈΠ»ΠΈ ΠΠΠΠ, ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ Π±ΡΠ»ΠΈ ΠΌΠ΅Π½ΡΡΠ΅Π³ΠΎ ΠΎΠ±ΡΠ΅ΠΌΠ° ΠΈ ΠΎΡΠΌΠ΅ΡΠ°Π»ΠΈ ΡΠ²Π΅Π»ΠΈΡΠ΅Π½ΠΈΠ΅ ΠΏΡΠΎΠ΄ΠΎΠ»ΠΆΠΈΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ ΠΆΠΈΠ·Π½ΠΈ
ΠΆΠΈΠ²ΠΎΡΠ½ΡΡ
. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ Π ΠΏΡΠΎΡΠ΅ΠΈΠ½ ΠΏΡΠΎΡΠ²Π»ΡΠ΅Ρ Π°Π½ΡΠΈΠ°Π½Π³ΠΈΠΎΠ³Π΅Π½Π½ΡΠ΅ ΡΠ²ΠΎΠΉΡΡΠ²Π° ΠΈ ΠΎΠ±Π»Π°Π΄Π°Π΅Ρ ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΡΡ ΠΈΠ½Π΄ΡΡΠΈΡΠΎΠ²Π°ΡΡ Π°ΠΏΠΎΠΏΡΠΎΠ·.
ΠΡΠ²ΠΎΠ΄Ρ: Π ΠΏΡΠΎΡΠ΅ΠΈΠ½ ΠΠΠ‘ ΠΈΠ½Π³ΠΈΠ±ΠΈΡΡΠ΅Ρ ΡΠΎΡΡ Π³Π»ΠΈΠΎΠΌΡ in ΠΈ in. ΠΠ° ΡΡΠΎΠΉ ΠΎΡΠ½ΠΎΠ²Π΅ ΠΌΠΎΠΆΠ΅Ρ Π±ΡΡΡ ΡΠ°Π·ΡΠ°Π±ΠΎΡΠ°Π½Π° ΠΏΠΎΡΠ΅Π½ΡΠΈΠ°Π»ΡΠ½ΠΎ Π½ΠΎΠ²Π°Ρ
Π±ΠΈΠΎΡΠ΅ΡΠ°ΠΏΠ΅Π²ΡΠΈΡΠ΅ΡΠΊΠ°Ρ ΡΡΡΠ°ΡΠ΅Π³ΠΈΡ Π΄Π»Ρ Π»Π΅ΡΠ΅Π½ΠΈΡ ΠΏΠ°ΡΠΈΠ΅Π½ΡΠΎΠ² Ρ Π³Π»ΠΈΠΎΠΌΠ°ΠΌΠΈ
Interacting Agegraphic Dark Energy
A new dark energy model, named "agegraphic dark energy", has been proposed
recently, based on the so-called K\'{a}rolyh\'{a}zy uncertainty relation, which
arises from quantum mechanics together with general relativity. In this note,
we extend the original agegraphic dark energy model by including the
interaction between agegraphic dark energy and pressureless (dark) matter. In
the interacting agegraphic dark energy model, there are many interesting
features different from the original agegraphic dark energy model and
holographic dark energy model. The similarity and difference between agegraphic
dark energy and holographic dark energy are also discussed.Comment: 10 pages, 5 figures, revtex4; v2: references added; v3: accepted by
Eur. Phys. J. C; v4: published versio
Heat transport of electron-doped Cobaltates
Within the t-J model, the heat transport of electron-doped cobaltates is
studied based on the fermion-spin theory. It is shown that the temperature
dependent thermal conductivity is characterized by the low temperature peak
located at a finite temperature. The thermal conductivity increases
monotonously with increasing temperature at low temperatures T 0.1, and
then decreases with increasing temperature for higher temperatures T
0.1, in qualitative agreement with experimental result observed from
NaCoO .Comment: 4 pages, 1 fig, corrected typos, accepted for publication in Commun.
Theor. Phy
Non-Markovian entanglement dynamics in coupled superconducting qubit systems
We theoretically analyze the entanglement generation and dynamics by coupled
Josephson junction qubits. Considering a current-biased Josephson junction
(CBJJ), we generate maximally entangled states. In particular, the entanglement
dynamics is considered as a function of the decoherence parameters, such as the
temperature, the ratio between the reservoir cutoff
frequency and the system oscillator frequency , % between
the characteristic frequency of the %quantum system of interest, and
the cut-off frequency of %Ohmic reservoir and the energy levels
split of the superconducting circuits in the non-Markovian master equation. We
analyzed the entanglement sudden death (ESD) and entanglement sudden birth
(ESB) by the non-Markovian master equation. Furthermore, we find that the
larger the ratio and the thermal energy , the shorter the
decoherence. In this superconducting qubit system we find that the entanglement
can be controlled and the ESD time can be prolonged by adjusting the
temperature and the superconducting phases which split the energy
levels.Comment: 13 pages, 3 figure
Isotope effects and possible pairing mechanism in optimally doped cuprate superconductors
We have studied the oxygen-isotope effects on T_{c} and in-plane penetration
depth \lambda_{ab}(0) in an optimally doped 3-layer cuprate
Bi_{1.6}Pb_{0.4}Sr_{2}Ca_{2}Cu_{3}O_{10+y} (T_{c} \sim 107 K). We find a small
oxygen-isotope effect on T_{c} (\alpha_{O} = 0.019), and a substantial effect
on \lambda_{ab} (0) (\Delta \lambda_{ab} (0)/\lambda_{ab} (0) = 2.5\pm0.5%).
The present results along with the previously observed isotope effects in
single-layer and double-layer cuprates indicate that the isotope exponent
\alpha_{O} in optimally doped cuprates is small while the isotope effect on the
in-plane effective supercarrier mass is substantial and nearly independent of
the number of the CuO_{2} layers. A plausible pairing mechanism is proposed to
explain the isotope effects, high-T_{c} superconductivity and tunneling spectra
in a consistent way.Comment: 5 pages, 4 figure
Kinetic energy driven superconductivity in the electron doped cobaltate NaCoOHO
Within the charge-spin separation fermion-spin theory, we have shown that the
mechanism of superconductivity in the electron doped cobaltate
NaCoOHO is ascribed to its kinetic energy. The dressed
fermions interact occurring directly through the kinetic energy by exchanging
magnetic excitations. This interaction leads to a net attractive force between
dressed fermions, then the electron Cooper pairs originating from the dressed
fermion pairing state are due to the charge-spin recombination, and their
condensation reveals the superconducting ground state. The superconducting
transition temperature is identical to the dressed fermion pair transition
temperature, and is suppressed to a lower temperature due to the strong
magnetic frustration. The optimal superconducting transition temperature occurs
in the electron doping concentration , and then decreases
for both underdoped and overdoped regimes, in qualitative agreement with the
experimental results.Comment: 6 pages, 2 figs, corrected typos, accepted for publication in Commun.
Theor. Phy
Another Two Dark Energy Models Motivated from Karolyhazy Uncertainty Relation
The Krolyhzy uncertainty relation
indicates that there exists the minimal detectable cell over the
region in Minkowski spacetime. Due to the energy-time uncertainty
relation, the energy of the cell can not be less .
Then we get a new energy density of metric fluctuations of Minkowski spacetime
as . Motivated by the energy density, we propose two new dark
energy models. One model is characterized by the age of the universe and the
other is characterized by the conformal age of the universe. We find that in
the two models, the dark energy mimics a cosmological constant in the late
time.Comment: 10 pages, 5 figures, References are adde
Solidification of Al alloys under electromagnetic pulses and characterization of the 3D microstructures under synchrotron x-ray tomography
A novel programmable electromagnetic pulse device was developed and used to study the solidification of Al-15 pct Cu and Al-35 pct Cu alloys. The pulsed magnetic fluxes and Lorentz forces generated inside the solidifying melts were simulated using finite element methods, and their effects on the solidification microstructures were characterized using electron microscopy and synchrotron X-ray tomography. Using a discharging voltage of 120 V, a pulsed magnetic field with the peak Lorentz force of ~1.6 N was generated inside the solidifying Al-Cu melts which were showed sufficiently enough to disrupt the growth of the primary Al dendrites and the Al2Cu intermetallic phases. The microstructures exhibit a strong correlation to the characteristics of the applied pulse, forming a periodical pattern that resonates the frequency of the applied electromagnetic field
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