530 research outputs found
Integrated photonic qubit quantum computing on a superconducting chip
We study a quantum computing system using microwave photons in transmission
line resonators on a superconducting chip as qubits. We show that all control
necessary for quantum computing can be implemented by coupling to Josephson
devices on the same chip, and take advantage of their strong inherent
nonlinearities to realize qubit interactions. We analyze the gate error rate to
demonstrate that our scheme is realistic even for Josephson devices with
limited decoherence times. A conceptually innovative solution based on existing
technologies, our scheme provides an integrated and scalable approach to the
next key milestone for photonic qubit quantum computing.Comment: 5 pages, 3 figure
Poly[[[μ-1,1′-(butane-1,4-diÂyl)diimidazole-κ2 N 3:N 3′](μ-cycloÂhexane-1,4-dicarboxylÂato-κ4 O 1,O 1′:O 4,O 4′)nickel(II)] 0.25-hydrate]
In the title coordination polymer, {[Ni(C8H10O4)(C10H14N4)]·0.25H2O}n, the coordination of the NiII ion is distorted octaÂhedral. The 1,1′-(butane-1,4-diÂyl)diimidazole ligand and the cycloÂhexane-1,4-dicarboxylÂate dianion bridge metal centres, forming a two-dimensional (4,4) network. The network is consolidated by O—H⋯O hydrogen bonds between the statistically occupied water molecules and O atoms of the two carboxylate groups
Exchange-biased hybrid gamma-Fe2O3/NiO core-shell nanostructures:three-step synthesis, microstructure, and magnetic properties
A two-step solvothermal method combining a calcination process was conducted to synthesize gamma-Fe2O3/NiO core-shell nanostructures with controlled microstructure. The formation mechanism of this binary system has been discussed, and the influence of microstructures on magnetic properties has been analyzed in detail. Microstructural characterizations reveal that the NiO shells consisted of many irregular nanosheets with disordered orientations and monocrystalline structures, packed on the surface of the gamma-Fe2O3 microspheres. Both the grain size and NiO content of nanostructures increase with the increasing calcination temperature from 300 degrees C to 400 degrees C, accompanied by an enhancement of the compactness of NiO shells. Magnetic studies indicate that their magnetic properties are determined by four factors: the size effect, NiO phase content, interface microstructure, i.e. contact mode, area, roughness and compactness, and FM-AFM (where FM and AFM denote the ferromagnetic gamma-Fe2O3 and the antiferromagnetic NiO components, respectively) coupling effect. At 5 K, the gamma-Fe2O3/NiO core-shell nanostructures display certain exchange bias (H-E = 60 Oe) and enhanced coercivity (H-C = 213 Oe)
Eliminating Plasmodium falciparum in Hainan, China: a study on the use of behavioural change communication intervention to promote malaria prevention in mountain worker populations
BACKGROUND: In the island of Hainan, the great majority of malaria cases occur in mountain worker populations. Using the behavioral change communication (BCC) strategy, an interventional study was conducted to promote mountain worker malaria prevention at a test site. This study found the methods and measures that are suitable for malaria prevention among mountain worker populations. METHODS: During the Plasmodium falciparum elimination stage in Hainan, a representative sampling method was used to establish testing and control sites in areas of Hainan that were both affected by malaria and had a relatively high density of mountain workers. Two different methods were used: a BCC strategy and a conventional strategy as a control. Before and after the intervention, house visits, core group discussions, and structural surveys were utilized to collect qualitative and quantitative data regarding mountain worker populations (including knowledge, attitudes, and practices [KAPs]; infection status; and serological data), and these data from the testing and control areas were compared to evaluate the effectiveness of BCC strategies in the prevention of malaria. RESULTS: In the BCC malaria prevention strategy testing areas, the accuracy rates of malaria-related KAP were significantly improved among mountain worker populations. The accuracy rates in the 3 aspects of malaria-related KAP increased from 37.73%, 37.00%, and 43.04% to 89.01%, 91.53%, and 92.25%, respectively. The changes in all 3 aspects of KAP were statistically significant (p < 0.01). In the control sites, the changes in the indices were not as marked as in the testing areas, and the change was not statistically significant (p > 0.05). Furthermore, in the testing areas, both the percentage testing positive in the serum malaria indirect fluorescent antibody test (IFAT) and the number of people inflicted decreased more significantly than in the control sites (p < 0.01). CONCLUSION: The use of the BCC strategy significantly improved the ability of mountain workers in Hainan to avoid malarial infection. Educational and promotional materials and measures were developed and selected in the process, and hands-on experience was gained that will help achieve the goal of total malaria elimination in Hainan
Reduced tolerance to abiotic stress in transgenic Arabidopsis overexpressing a Capsicum annuum multiprotein bridging factor 1
BACKGROUND: The pepper fruit is the second most consumed vegetable worldwide. However, low temperature affects the vegetative development and reproduction of the pepper, resulting in economic losses. To identify cold-related genes regulated by abscisic acid (ABA) in pepper seedlings, cDNA representational difference analysis was previously performed using a suppression subtractive hybridization method. One of the genes cloned from the subtraction was homologous to Solanum tuberosum MBF1 (StMBF1) encoding the coactivator multiprotein bridging factor 1. Here, we have characterized this StMBF1 homolog (named CaMBF1) from Capsicum annuum and investigated its role in abiotic stress tolerance. RESULTS: Tissue expression profile analysis using quantitative RT-PCR showed that CaMBF1 was expressed in all tested tissues, and high-level expression was detected in the flowers and seeds. The expression of CaMBF1 in pepper seedlings was dramatically suppressed by exogenously supplied salicylic acid, high salt, osmotic and heavy metal stresses. Constitutive overexpression of CaMBF1 in Arabidopsis aggravated the visible symptoms of leaf damage and the electrolyte leakage of cell damage caused by cold stress in seedlings. Furthermore, the expression of RD29A, ERD15, KIN1, and RD22 in the transgenic plants was lower than that in the wild-type plants. On the other hand, seed germination, cotyledon greening and lateral root formation were more severely influenced by salt stress in transgenic lines compared with wild-type plants, indicating that CaMBF1-overexpressing Arabidopsis plants were hypersensitive to salt stress. CONCLUSIONS: Overexpression of CaMBF1 in Arabidopsis displayed reduced tolerance to cold and high salt stress during seed germination and post-germination stages. CaMBF1 transgenic Arabidopsis may reduce stress tolerance by downregulating stress-responsive genes to aggravate the leaf damage caused by cold stress. CaMBF1 may be useful for genetic engineering of novel pepper cultivars in the future
TMRT observations of 26 pulsars at 8.6 GHz
Integrated pulse profiles at 8.6~GHz obtained with the Shanghai Tian Ma Radio
Telescope (TMRT) are presented for a sample of 26 pulsars. Mean flux densities
and pulse width parameters of these pulsars are estimated. For eleven pulsars
these are the first high-frequency observations and for a further four, our
observations have a better signal-to-noise ratio than previous observations.
For one (PSR J0742-2822) the 8.6~GHz profiles differs from previously observed
profiles. A comparison of 19 profiles with those at other frequencies shows
that in nine cases the separation between the outmost leading and trailing
components decreases with frequency, roughly in agreement with
radius-to-frequency mapping, whereas in the other ten the separation is nearly
constant. Different spectral indices of profile components lead to the
variation of integrated pulse profile shapes with frequency. In seven pulsars
with multi-component profiles, the spectral indices of the central components
are steeper than those of the outer components. For the 12 pulsars with
multi-component profiles in the high-frequency sample, we estimate the core
width using gaussian fitting and discuss the width-period relationship.Comment: 33 pages, 49 figures, 5 Tables; accepted by Ap
Observation of first-order quantum phase transitions and ferromagnetism in twisted double bilayer graphene
Twisted graphene multilayers are highly tunable flatband systems for
developing new phases of matter. Thus far, while orbital ferromagnetism has
been observed in valley polarized phases, the long-range orders of other
correlated phases as well as the quantum phase transitions between different
orders mostly remain unknown. Here, we report an observation of Coulomb
interaction driven first-order quantum phase transitions and ferromagnetism in
twisted double bilayer graphene (TDBG). At zero magnetic field, the transitions
are revealed in a series of step-like abrupt resistance jumps with prominent
hysteresis loop when either the displacement field (D) or the carrier density
(n) is tuned across symmetry-breaking boundary near half filling, indicating a
formation of ordered domains. It is worth noting that the good turnability and
switching of these states gives a rise to a memory performance with a large
on/off ratio. Moreover, when both spin and valley play the roles at finite
magnetic field, we observe abundant first-order quantum phase transitions among
normal metallic states from charge neutral point, orbital ferromagnetic states
from quarter filling, and spin-polarized states from half filling. We interpret
these first-order phase transitions in the picture of phase separations and
spin domain percolations driven by multi-field tunable Coulomb interactions, in
agreement with Lifshitz transition from Hartree-Fock calculations. The observed
multi-filed tunable domain structure and its hysteresis resembles the
characteristics of multiferroics, revealing intriguing magnetoelectric
properties. Our result enriches the correlated phase diagram in TDBG for
discovering novel exotic phases and quantum phase transitions, and it would
benefit other twisted moir\'e systems as well
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