6,025 research outputs found
Quantum Phases and Collective Excitations in Bose-Hubbard Models with Staggered Magnetic Flux
We study the quantum phases of a Bose-Hubbard model with staggered magnetic
flux in two dimensions, as has been realized recently [Aidelsburger {\it et
al.}, PRL, {\bf 107}, 255301 (2011)]. Within mean field theory, we show how the
structure of the condensates evolves from weak to strong coupling limit,
exhibiting a tricritical point at the Mott-superfluid transition. Non-trivial
topological structures (Dirac points) in the quasi-particle (hole) excitations
in the Mott state are found within random phase approximation and we discuss
how interaction modifies their structures. Excitation gap in the Mott state
closes at different points when approaching the superfluid states,
which is consistent with the findings of mean field theory.Comment: 5 pages, 3 figure
Quantum state tomography with disentanglement algorithm
In this work, we report on a novel quantum state reconstruction process based
on the disentanglement algorithm. Using variational quantum circuits, we
disentangle the quantum state to a product of computational zero states.
Inverse evolution of the zero states reconstructs the quantum state up to an
overall phase. By sequentially disentangling the qubit one by one, we reduce
the required measurements with only single qubit measurement. Demonstrations
with our proposal for the reconstruction of the random states are presented
where variational quantum circuit is optimized by disentangling process. To
facilitate experimental implementation, we also employ reinforcement learning
for quantum circuit design with limited discrete quantum gates. Our method is
universal and imposes no specific ansatz or constrain on the quantum state.Comment: 5 pages, 6 figure
Positivity constraints on the low-energy constants of the chiral pion-nucleon Lagrangian
Positivity constraints on the pion-nucleon scattering amplitude are derived
in this article with the help of general S-matrix arguments, such as
analyticity, crossing symmetry and unitarity, in the upper part of Mandelstam
triangle, R. Scanning inside the region R, the most stringent bounds on the
chiral low energy constants of the pion-nucleon Lagrangian are determined. When
just considering the central values of the fit results from covariant baryon
chiral perturbation theory using extended-on-mass-shell scheme, it is found
that these bounds are well respected numerically both at O(p^3) and O(p^4)
level. Nevertheless, when taking the errors into account, only the O(p^4)
bounds are obeyed in the full error interval, while the bounds on O(p^3) fits
are slightly violated. If one disregards loop contributions, the bounds always
fail in certain regions of R. Thus, at a given chiral order these terms are not
numerically negligible and one needs to consider all possible contributions,
i.e., both tree-level and loop diagrams. We have provided the constraints for
special points in R where the bounds are nearly optimal in terms of just a few
chiral couplings, which can be easily implemented and employed to constrain
future analyses. Some issues about calculations with an explicit Delta(1232)
resonance are also discussed.Comment: 15 pages, 13 eps figures, 2 table
TRPV4, TRPC1, and TRPP2 assemble to form a flow-sensitive heteromeric channel
Transient receptor potential (TRP) channels, a superfamily of ion channels, can be divided into 7 subfamilies, including TRPV, TRPC, TRPP, and 4 others. Functional TRP channels are tetrameric complexes consisting of 4 pore-forming subunits. The purpose of this study was to explore the heteromerization of TRP subunits crossing different TRP subfamilies. Two-step coimmunoprecipitation (co-IP) and fluorescence resonance energy transfer (FRET) were used to determine the interaction of the different TRP subunits. Patch-clamp and cytosolic Ca2+ measurements were used to determine the functional role of the ion channels in flow conditions. The analysis demonstrated the formation of a heteromeric TRPV4-C1-P2 complex in primary cultured rat mesenteric artery endothelial cells (MAECs) and HEK293 cells that were cotransfected with TRPV4, TRPC1, and TRPP2. In functional experiments, pore-dead mutants for each of these 3 TRP isoforms nearly abolished the flow-induced cation currents and Ca2+ increase, suggesting that all 3 TRPs contribute to the ion permeation pore of the channels. We identified the first heteromeric TRP channels composed of subunits from 3 different TRP subfamilies. Functionally, this heteromeric TRPV4- C1-P2 channel mediates the flow-induced Ca2+ increase in native vascular endothelial cells.-Du, J., Ma, X., Shen, B., Huang, Y., Birnbaumer, L., Yao, X. TRPV4, TRPC1, and TRPP2 assemble to form a flowsensitive heteromeric channel.Fil: Du, Juan. Chinese University Of Hong Kong; Hong Kong. Anhui Medical University; ChinaFil: Ma, Xin. Chinese University Of Hong Kong; Hong KongFil: Shen, Bing. Chinese University Of Hong Kong; Hong Kong. Anhui Medical University; ChinaFil: Huang, Yu. Chinese University Of Hong Kong; Hong KongFil: Birnbaumer, Lutz. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. National Institutes of Health; Estados UnidosFil: Yao, Xiaoqiang. Chinese University Of Hong Kong; Hong Kon
3,19-Diacetyl-12-nitroÂmethyl-14-deoxyÂandrographolide
In the crystal of the title compound, C24H33NO9, interÂmolecular C—H⋯O hydrogen bonds link the molÂecules
MONITORING DATA PRODUCT QUALITY
The importance of data quality has been considered for many years and is well recognized among practitioners and researchers. A great deal of work has been done and most of the work to date fall under two main categories. One group of scientists has focused on mathematical and statistical model to work at the database layer to introduce constrain based mechanism to prevent data quality problems. Another group has focused on the management of the process of data generation. While the body of knowledge in the area is vast, the practical application of these approaches is still limited. One particular area which is still rarely considered in improving data quality is the development cycle of information system. Recognising this limitation and aiming to provide a practical-orient approach, we take a process centric view, and focus on preventing deficiencies during the IS design. In this paper we propose a process centric framework for data quality monitoring
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