5,174 research outputs found
State Transfer of Two-level Quantum System Feedback Control Based on Online State Estimation
A quantum state feedback control method is proposed in this paper. The state of a two-level open quantum system is estimated online based on the continuous weak measurement and the compressed sensing theory. Based on the state estimated online and the Lyapunov stability theorem, the state feedback control law used to transfer the quantum state is designed. Moreover, three numerical simulation experiments are implemented in the MATLAB environment: the state transfer from eigenstates to eigenstates, superposition states to superposition states, and superposition states to mixed states. The experimental results verify high performance of the proposed feedback control based on the state estimated online
One-step Conjugation of Glycyrrhetinic Acid to Cationic Polymers for High-performance Gene Delivery to Cultured Liver Cell
Gene therapies represent a promising therapeutic route for liver cancers, but major challenges remain in the design of safe and efficient gene-targeting delivery systems. For example, cationic polymers show good transfection efficiency as gene carriers, but are hindered by cytotoxicity and non-specific targeting. Here we report a versatile method of one-step conjugation of glycyrrhetinic acid (GA) to reduce cytotoxicity and improve the cultured liver cell-targeting capability of cationic polymers. We have explored a series of cationic polymer derivatives by coupling different ratios of GA to polypropylenimine (PPI) dendrimer. These new gene carriers (GA-PPI dendrimer) were systematically characterized by UV-vis, 1 H NMR titration, electron microscopy, zeta potential, dynamic light-scattering, gel electrophoresis, confocal microscopy and flow cytometry. We demonstrate that GA-PPI dendrimers can efficiently load and protect pDNA, via formation of nanostructured GA-PPI/pDNA polyplexes. With optimal GA substitution degree (6.31%), GA-PPI dendrimers deliver higher liver cell transfection efficiency (43.5% vs 22.3%) and lower cytotoxicity (94.3% vs 62.5%, cell viability) than the commercial bench-mark DNA carrier bPEI (25kDa) with cultured liver model cells (HepG 2). There results suggest that our new GA-PPI dendrimer are a promising candidate gene carrier for targeted liver cancer therapy
Quantum Criticality of an Ising-like Spin-1/2 Antiferromagnetic Chain in Transverse Magnetic Field
We report on magnetization, sound velocity, and magnetocaloric-effect
measurements of the Ising-like spin-1/2 antiferromagnetic chain system
BaCoVO as a function of temperature down to 1.3 K and applied
transverse magnetic field up to 60 T. While across the N\'{e}el temperature of
K anomalies in magnetization and sound velocity confirm the
antiferromagnetic ordering transition, at the lowest temperature the
field-dependent measurements reveal a sharp softening of sound velocity
and a clear minimum of temperature at T,
indicating the suppression of the antiferromagnetic order. At higher fields,
the curve shows a broad minimum at T, accompanied by a
broad minimum in the sound velocity and a saturation-like magnetization. These
features signal a quantum phase transition which is further characterized by
the divergent behavior of the Gr\"{u}neisen parameter . By contrast, around the critical field, the
Gr\"{u}neisen parameter converges as temperature decreases, pointing to a
quantum critical point of the one-dimensional transverse-field Ising model.Comment: Phys. Rev. Lett., to appea
Effect of Reducing Atmosphere on the Magnetism of Zn1-xCoxO Nanoparticles
We report the crystal structure and magnetic properties of Zn1-xCoxO
nanoparticles synthesized by heating metal acetates in organic solvent. The
nanoparticles were crystallized in wurtzite ZnO structure after annealing in
air and in a forming gas (Ar95%+H5%). The X-ray diffraction and X-ray
photoemission spectroscopy (XPS) data for different Co content show clear
evidence for the Co+2 ions in tetrahedral symmetry, indicating the substitution
of Co+2 in ZnO lattice. However samples with x=0.08 and higher cobalt content
also indicate the presence of Co metal clusters. Only those samples annealed in
the reducing atmosphere of the forming gas, and that showed the presence of
oxygen vacancies, exhibited ferromagnetism at room temperature. The air
annealed samples remained non-magnetic down to 77K. The essential ingredient in
achieving room temperature ferromagnetism in these Zn1-xCoxO nanoparticles was
found to be the presence of additional carriers generated by the presence of
the oxygen vacancies.Comment: 11 pages, 6 figures, submitted to Nanotechnology IO
Concentration, temporal variation, and sources of black carbon in the Mt. Everest region retrieved by real-time observation and simulation
Based on the high-resolution measurement of black carbon (BC) at the
Qomolangma (Mt. Everest) Station (QOMS, 28.36° N, 86.95° E,
4276 m a.s.l.) from 15 May 2015 to 31 May 2017, we investigated the
seasonal and diurnal variations in BC and its potential source regions. Both
monthly and daily mean BC concentrations reached the highest values in the
pre-monsoon season and the lowest values in the monsoon season. The highest
monthly and daily mean BC concentrations were at least 1 order of magnitude
higher than the lowest concentrations. For the diurnal variation, the BC
concentrations remained significantly high from late at night to morning in
the pre-monsoon season. Meanwhile, the westerly winds prevailed during this
period, implying the potential for pollutants to be transported across the
Himalayas from long-distance sources to QOMS along the valley. In the monsoon
season, the BC concentrations remained low but peaked in the morning and at
noon, which might be caused by local emissions from cooking. By
analyzing the simulation results from the backward trajectories of air masses
and the fire spot distribution from the MODIS data, we found that the
seasonal cycle of BC was significantly influenced by the atmospheric
circulation and combustion intensity in the Mt. Everest region. The transport
mechanisms of BC were further revealed using a WRF-Chem simulation during
severe pollution episodes. For the pollution event in the monsoon season, BC
aerosols in southern Asia were uplifted and transported to the Mt. Everest
region by the southerly winds in the upper atmosphere. However, for the
events in the pre-monsoon season, BC from northern India was transported and
concentrated on the southern slope of the Himalayas by the northwesterly
winds in the lower atmosphere and then transported across the Himalayas by
the mountain-valley wind. A relatively smaller amount of BC from northwestern
India and central Asia was transported to the Mt. Everest region by the
westerly winds in the upper atmosphere.</p
Tracking System with Re-identification Using a RGB String Kernel
International audiencePeople re-identification consists to identify a person which comes back in a scene where it has been previously detected. This key problem in visual surveillance applications may concern single or multi camera systems. Features encoding each person should be rich enough to provide an efficient re-identification while being sufficiently robust to remain significant through the different phenomena which may alter the appearance of a person in a video. We propose in this paper a method which encodes people's appearance through a string of salient points. The similarity between two such strings is encoded by a kernel. This last kernel is combined with a tracking algorithm in order to associate a set of strings to each person and to measure similarities between persons entering into the scene and persons who left it
- …