619 research outputs found
as a molecule from the pole counting rule
A comprehensive study on the nature of the resonant structure is
carried out in this work. By constructing the pertinent effective Lagrangians
and considering the important final-state-interaction effects, we first give a
unified description to all the relevant experimental data available, including
the and invariant mass distributions from the process, the distribution from and
also the spectrum in the process.
After fitting the unknown parameters to the previous data, we search the pole
in the complex energy plane and find only one pole in the nearby energy region
in different Riemann sheets. Therefore we conclude that is of
molecular nature, according to the pole counting rule
method~[Nucl.~Phys.~A543, 632 (1992); Phys.~Rev.~D 35,~1633 (1987)]. We
emphasize that the conclusion based upon the pole counting method is not
trivial, since both the contact interactions and the explicit
exchanges are introduced in our analyses and they lead to the same
conclusion.Comment: 21 pages, 9 figures. To match the published version in PRD.
Additional discussion on the spectral density function is include
Tribological properties of surface dimple-textured by pellet-pressing
AbstractSurface texturing is thought to be as an effective tribological method of decreasing friction coefficient of contact pairs. Firstly, AISI1045 steel surface is dimple-textured by a convenient and economical way of pellet-pressing, then, the textured and polished samples is against SiC ball lubricated by engine oil to carry out tribological tests in reciprocating mode in tribomachine type UMT-II. It is concluded that surface dimple-texture made by pellet-pressing is beneficial to improve tribological properties lubricated by engine oil under10N load and 5mm/s sliding speed
Effects of diurnal fluctuation of temperature on growth, photosynthetic activity response of two morphotypes cells of Emiliania huxleyi
349-356The effects of different thermal regimes on growth and physiological performance of the marine microalgae Emiliania huxleyi were studied . Two morphological distinct strains, one coccoliths-bearing cells called Calcified cells and one non-motile naked cells, were allocated to four different experimental groups. The groups were submitted to constant temperature of 20 °C and three different daily fluctuation ranges of temperature: a lower range of 20±2 °C, an intermediate range of 20±4 °C and the last higher range of 20±6 °C. This investigation demonstrated that there is a correlation between degree of calcification and photosynthesis. The cells with a decreased level of calcification resulted in a down regulation of photoprotective mechanisms. The cells grew high extent for all levels of fluctuation, presenting elevated concentrations at higher temperature amplitude. Elevated temperature shifts (20±6 °C) increased photosynthetic activity on both morphotypes strains of E. huxleyi
Phase diagram and magnetic excitations of - Heisenberg model on the square lattice
We study the phase diagram and the dynamical spin structure factor of the
spin-1/2 J1-J3 Heisenberg model on the square lattice using density matrix
renormalization group, exact diagonalization (ED), and cluster perturbation
theory (CPT). By extrapolating the order parameters and studying the level
crossings of the low-lying energy and entanglement spectra, we obtain the phase
diagram of this model and identify a narrow region of quantum spin liquid (QSL)
phase followed by a plaquette valence-bond solid (PVBS) state in the
intermediate region, whose nature has been controversial for many years. More
importantly, we use CPT and ED to study the dynamical spin structure factor in
the QSL and the PVBS phase. In the QSL phase, the high-energy magnon mode
completely turns into some dispersive weak excitations around the X and M
points. For the PVBS phase, the low-energy spectrum is characterized by a
gapped triplet excitation, and at the high energy, we find another branch of
dispersive excitation with broad continua, which is unlike the plaquette phase
in the 2x2 checkerboard model. In the latter case, the second branch of
excitation is nearly flat due to the weak effective interactions between the
local excitations of the plaquettes. And in the J1-J3 Heisenberg model, the
uniform interactions and the spontaneously translational symmetry breaking of
the PVBS phase make the difference in the excitation spectra.Comment: 14 pages, 14 figure
Haldane phases and phase diagrams of the S = 3/2, 1 bilinear-biquadratic Heisenberg model on the orthogonal dimer chain
We systematically study the effects of higher-order interactions on the S =
3/2, 1 orthogonal dimer chains using exact diagonalization and density matrix
renormalization group. Due to frustration and higher spin, there are rich
quantum phases, including three Haldane phases, two gapless phases and several
magnetically ordered phases. To characterize these phases and their phase
transitions, we study various physical quantities such as energy gap, energy
level crossing, fidelity susceptibility, spin correlation, entanglement
spectrum and central charge. According to our calculations, the biquadratic
term can enhance the Haldane phase regions. In particular, we numerically
identify that a Haldane phase in S = 3/2 case is adiabatically connected to the
exact AKLT point when adding bicubic term. Our study on the orthogonal dimer
model, which is a 1D version of Shastry-Sutherland model, provides insights
into understanding the possible S = 3/2, 1 Haldane phases in quasi-1D and 2D
frustrated magnetic materials.Comment: 14 pages, 17 figure
Characterizing random-singlet state in two-dimensional frustrated quantum magnets and implications for the double perovskite SrCuTeWO
Motivated by experimental observation of the non-magnetic phase in the
compounds with frustration and disorder, we study the ground state of the
spin- square-lattice Heisenberg model with randomly distributed
nearest-neighbor and next-nearest-neighbor couplings. By using the
density matrix renormalization group (DMRG) calculation on cylinder system with
circumference up to lattice sites, we identify a disordered phase between
the N\'eel and stripe magnetic phase with growing in the presence
of strong randomness. The vanished spin-freezing parameter indicates the absent
spin glass order. The large-scale DMRG results unveil the size-scaling
behaviors of the spin-freezing parameter, the power-law decay of average spin
correlation, and the exponential decay of typical spin correlation, which all
agree with the corresponding behavior in the one-dimensional random singlet
(RS) state and characterize the RS nature of this non-magnetic state. The DMRG
simulation also opens new insight and opportunities for characterizing a class
of non-magnetic states in two-dimensional frustrated magnets with disorder. We
also compare with existing experiments and suggest more measurements for
understanding the spin-liquid-like behavior in the double perovskite
SrCuTeWO.Comment: 11 pages,10 figure
Identification of Magnetic Interactions and High-field Quantum Spin Liquid in -RuCl
The frustrated magnet -RuCl constitutes a fascinating quantum
material platform that harbors the intriguing Kitaev physics. However, a
consensus on its intricate spin interactions and field-induced quantum phases
has not been reached yet. Here we exploit multiple state-of-the-art many-body
methods and determine the microscopic spin model that quantitatively explains
major observations in -RuCl, including the zigzag order,
double-peak specific heat, magnetic anisotropy, and the characteristic M-star
dynamical spin structure, etc. According to our model simulations, the in-plane
field drives the system into the polarized phase at about 7 T and a thermal
fractionalization occurs at finite temperature, reconciling observations in
different experiments. Under out-of-plane fields, the zigzag order is
suppressed at 35 T, above which, and below a polarization field of 100 T level,
there emerges a field-induced quantum spin liquid. The fractional entropy and
algebraic low-temperature specific heat unveil the nature of a gapless spin
liquid, which can be explored in high-field measurements on -RuCl.Comment: To appear in Nature Communications (12 pages, 6 figures, and 5
Supplementary Notes
ChemiQ: A Chemistry Simulator for Quantum Computer
Quantum computing, an innovative computing system carrying prominent
processing rate, is meant to be the solutions to problems in many fields. Among
these realms, the most intuitive application is to help chemical researchers
correctly de-scribe strong correlation and complex systems, which are the great
challenge in current chemistry simulation. In this paper, we will present a
standalone quantum simulation tool for chemistry, ChemiQ, which is designed to
assist people carry out chemical research or molecular calculation on real or
virtual quantum computers. Under the idea of modular programming in C++
language, the software is designed as a full-stack tool without third-party
physics or chemistry application packages. It provides services as follow:
visually construct molecular structure, quickly simulate ground-state energy,
scan molecular potential energy curve by distance or angle, study chemical
reaction, and return calculation results graphically after analysis.Comment: software,7 pages, 5 figure
Discovering multiple transcripts of human hepatocytes using massively parallel signature sequencing (MPSS)
<p>Abstract</p> <p>Background</p> <p>The liver is the largest human internal organ – it is composed of multiple cell types and plays a vital role in fulfilling the body's metabolic needs and maintaining homeostasis. Of these cell types the hepatocytes, which account for three-quarters of the liver's volume, perform its main functions. To discover the molecular basis of hepatocyte function, we employed Massively Parallel Signature Sequencing (MPSS) to determine the transcriptomic profile of adult human hepatocytes obtained by laser capture microdissection (LCM).</p> <p>Results</p> <p>10,279 UniGene clusters, representing 7,475 known genes, were detected in human hepatocytes. In addition, 1,819 unique MPSS signatures matching the antisense strand of 1,605 non-redundant UniGene clusters (such as <it>APOC1</it>, <it>APOC2</it>, <it>APOB </it>and <it>APOH</it>) were highly expressed in hepatocytes.</p> <p>Conclusion</p> <p>Apart from a large number of protein-coding genes, some of the antisense transcripts expressed in hepatocytes could play important roles in transcriptional interference via a <it>cis</it>-/<it>trans</it>-regulation mechanism. Our result provided a comprehensively transcriptomic atlas of human hepatocytes using MPSS technique, which could be served as an available resource for an in-depth understanding of human liver biology and diseases.</p
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