9,887 research outputs found
Analysis of Photosynthetic Characteristics of \u3cem\u3eHeteropogon contortusin\u3c/em\u3e Arid‐Hot Valley Areas of Jinsha River
Effect of tartaric acid and phosphoric acid on the water resistance of magnesium oxychloride (MOC) cement
Magnesium oxychloride (MOC) cement is featured with high early strength, low thermal conductivity and low density, but is not widely applied in construction engineering due to its poor water resistance capability. This research has studied the effect of phosphoric acid and tartaric acid additions on the water resistance of MOC cement pastes, in which also reports the effects on setting time, hydration reactions, compressive strength, phase composition, thermal stability and microstructure. 1 wt% of phosphoric acid and tartaric acid additions can improve the water resistance and reduce thermal stability of MOC cement pastes, which is associated with formation of gel-like 5Mg(OH) 2 ·MgCl 2 ·8H 2 O. Moreover, these additions reduce the compressive strength and prolong the setting time of MOC cement pastes, as well as increase the total porosity, the volume fraction of gel pores (100 nm), however, decrease the volume fraction of small capillary pores (10–100 nm) of MOC cement pastes. These effects are caused by both additives but are most pronounced for MOC cement pastes containing phosphoric acid. In addition, 2Mg(OH) 2 ·MgCl 2 ·2H 2 O is a transitional phase in the formative stage of 5Mg(OH) 2 ·MgCl 2 ·8H 2 O in MOC cement
CP Asymmetry in Charged Higgs Decays in MSSM
We discuss and compare the charge-parity (CP) asymmetry in the charged Higgs
boson decays H -> \bar{u}_i d_j for the second and third generation quarks in
the minimal supersymmetric standard model. As part of the analysis, we derive
some general analytical formulas for the imaginary parts of two-point and
three-point scalar one-loop integrals and use them for calculating vectorial
and tensorial type integrals needed for the problem under consideration. We
find that, even though each decay mode has a potential to yield a CP asymmetry
larger than 10%, further analysis based on the number of required charged Higgs
events at colliders favors the \bar{t}b, \bar{c}b, and \bar{c}s channels, whose
asymmetry could reach 10-15% in certain parts of the parameter space.Comment: 25 pages, 9 figures. Discussion about charged Higgs observability
added, typos corrected, accepted for publication in PR
Heavy metals in an impacted wetland system : a typical case from southwestern China
Author name used in this publication: Grace P.Y. Sin2007-2008 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe
Allocation and source attribution of lead and cadmium in maize (Zea mays L.) impacted by smelting emissions
2008-2009 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe
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Predicting Conceptual Processing Capacity from Spontaneous Neuronal Activity of the Left Middle Temporal Gyrus
Conceptual processing is a crucial brain function for humans. Past research using neuropsychological and task-based functional brain-imaging paradigms indicates that widely distributed brain regions are related to conceptual processing. Here, we explore the potential contribution of intrinsic or spontaneous brain activity to conceptual processing by examining whether resting-state functional magnetic resonance imaging (rs-fMRI) signals can account for individual differences in the conceptual processing efficiencies of healthy individuals. We acquired rs-fMRI and behavioral data on object conceptual processing tasks. We found that the regional amplitude of spontaneous low-frequency fluctuations in the blood oxygen level-dependent signal in the left (posterior) middle temporal gyrus (LMTG) was highly correlated with participants' semantic processing efficiency. Furthermore, the strength of the functional connectivity between the LMTG and a series of brain regions-the left inferior frontal gyrus, bilateral anterior temporal lobe, bilateral medial temporal lobe, posterior cingulate gyrus, and ventromedial and dorsomedial prefrontal cortices-also significantly predicted conceptual behavior. The regional amplitude of low-frequency fluctuations and functionally relevant connectivity strengths of LMTG together accounted for 74% of individual variance in object conceptual performance. This semantic network, with the LMTG as its core component, largely overlaps with the regions reported in previous conceptual/semantic task-based fMRI studies. We conclude that the intrinsic or spontaneous activity of the human brain reflects the processing efficiency of the semantic system.Psycholog
Induced magnetization in LaSrMnO/BiFeO superlattices
Using polarized neutron reflectometry (PNR), we observe an induced
magnetization of 75 25 kA/m at 10 K in a LaSrMnO
(LSMO)/BiFeO superlattice extending from the interface through several
atomic layers of the BiFeO (BFO). The induced magnetization in BFO is
explained by density functional theory, where the size of bandgap of BFO plays
an important role. Considering a classical exchange field between the LSMO and
BFO layers, we further show that magnetization is expected to extend throughout
the BFO, which provides a theoretical explanation for the results of the
neutron scattering experiment.Comment: 5 pages, 4 figures, with Supplemental Materials. To appear in
Physical Review Letter
Effective one-band electron-phonon Hamiltonian for nickel perovskites
Inspired by recent experiments on the Sr-doped nickelates,
, we propose a minimal microscopic model capable to describe
the variety of the observed quasi-static charge/lattice modulations and the
resulting magnetic and electronic-transport anomalies. Analyzing the motion of
low-spin (s=1/2) holes in a high-spin (S=1) background as well as their their
coupling to the in-plane oxygen phonon modes, we construct a sort of
generalized Holstein t-J Hamiltonian for the planes, which contains
besides the rather complex ``composite-hole'' hopping part non-local spin-spin
and hole-phonon interaction terms.Comment: 12 pages, LaTeX, submitted to Phys. Rev.
Mott physics and band topology in materials with strong spin-orbit interaction
Recent theory and experiment have revealed that strong spin-orbit coupling
can have dramatic qualitative effects on the band structure of weakly
interacting solids. Indeed, it leads to a distinct phase of matter, the
topological band insulator. In this paper, we consider the combined effects of
spin-orbit coupling and strong electron correlation, and show that the former
has both quantitative and qualitative effects upon the correlation-driven Mott
transition. As a specific example we take Ir-based pyrochlores, where the
subsystem of Ir 5d electrons is known to undergo a Mott transition. At weak
electron-electron interaction, we predict that Ir electrons are in a metallic
phase at weak spin-orbit interaction, and in a topological band insulator phase
at strong spin-orbit interaction. Very generally, we show that with increasing
strength of the electron-electron interaction, the effective spin-orbit
coupling is enhanced, increasing the domain of the topological band insulator.
Furthermore, in our model, we argue that with increasing interactions, the
topological band insulator is transformed into a "topological Mott insulator"
phase, which is characterized by gapless surface spin-only excitations. The
full phase diagram also includes a narrow region of gapless Mott insulator with
a spinon Fermi surface, and a magnetically ordered state at still larger
electron-electron interaction.Comment: 10+ pages including 3+ pages of Supplementary Informatio
The empirical support for the radical cure strategy for eliminating Plasmodium vivax in China
BACKGROUND: With the recent certification by World Health Organization that the People's Republic of China is malaria-free, it is timely to consider how elimination of malaria was completed in People's Republic of China over the last 7 decades. Of the four widespread species of human malaria, Plasmodium vivax was the last to be eliminated by the national program of China. Understanding the incubation periods and relapses patterns of P. vivax through historical data from China is relevant for planning disease elimination in other malaria-endemic countries, with residual P. vivax malaria. METHODS: We collated data from both published and unpublished malaria parasite inoculation experiments conducted between 1979 and 1988 with parasites from different regions of the People's Republic of China. The studies had at least two years of follow-up. We categorized P. vivax incubation patterns via cluster analysis and investigated relapse studies by adapting a published within-host relapse model for P. vivax temperate phenotypes. Each model was fitted using the expectation-maximization (EM) algorithm initialized by hierarchical model-based agglomerative clustering. RESULTS: P. vivax parasites from the seven studies of five southern and central provinces in the People's Republic of China covering geographies ranging from the south temperate to north tropical zones. The parasites belonged to two distinct phenotypes: short- (10-19 days) or long-incubation (228-371 days). The larger the sporozoite inoculation, the more likely short incubation periods were observed, and with more subsequent relapses (Spearman's rank correlation between the number of inoculated sporozoites and the number of relapses of 0.51, p-value = 0.0043). The median of the posterior distribution for the duration of the first relapse interval after primary infection was 168.5 days (2.5% quantile: 89.7; 97.5% quantile: 227.69 days). The predicted survival proportions from the within-host model fit well to the original relapse data. The within-host model also captures the hypnozoite activation rates and relapse frequencies, which consequently influences the transmission possibility of P. vivax. CONCLUSIONS: Through a within-host model, we demonstrate the importance of clearance of hypnozoites. A strategy of two rounds of radical hypnozoite clearance via mass drug administration (MDA) deployed during transmission (summer and autumn) and non-transmission (late spring) seasons had a pronounced effect on outbreaks during the malaria epidemics in China. This understanding can inform malaria control strategies in other endemic countries with similar settings
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