3,520 research outputs found
Anomalous Phase Transition in Strained SrTiO Thin Films
We have studied the cubic to tetragonal phase transition in epitaxial
SrTiO films under various biaxial strain conditions using synchrotron X-ray
diffraction. Measuring the superlattice peak associated with TiO octahedra
rotation in the low temperature tetragonal phase indicates the presence of a
phase transition whose critical temperature is a strong function of strain,
with T as much as 50K above the corresponding bulk temperature.
Surprisingly, the lattice constants evolve smoothly through the transition with
no indication of a phase change. This signals an important change in the nature
of the phase transition due to the epitaxy strain and substrate clamping
effect. The internal degrees of freedom (TiO rotations) have become
uncoupled from the overall lattice shape.Comment: 4 pages, 3 figures, REVTeX
Inhibited effects of veliparib combined doxorubicin for BEL-7404 proliferation of human liver cancer cell line
AbstractObjectiveTo explore inhibition effects of veliparib as PARP inhibitor combined doxorubicin for BEL-7404 proliferation of human liver cancer cell line.MethodsBEL-7404 was taken as the object of study and conventional culture was performed. It wastreated by doxorubicin and (or) veliparib after 24 h. Cell proliferation rate was detected by four methyl thiazolyl tetrazolium (MTT) assay, cell apoptosis was measured with annexin V-FITC/PI double staining method by flow cytometry, DNA damage degree evaluation by single cell gel electrophoresis assay, and cytosolic C levels of the mitochondrial and cytosol by polyacrylamide gel electrophoresis (Western blotting).ResultsCell proliferation rate of doxorubicin combined veliparib group was lower than that of the control group and doxorubicin alone treated group significantly (P<0.01), the apoptosis rate was significantly higher than that of the control group and doxorubicin alone treated group (P<0.05). At the same time, DNA damage level of doxorubicin combined with veliparib group was significantly higher than doxorubicin alone treatment group and the control group (P<0.01), and cytochrome C in the cytosol was significantly higher than that of control group and doxorubicin alone treated group (P<0.01).ConclusionsVeliparib, PARP inhibitor could inhibit PARP activity, block tumor cell DNA repair, and have significant sensitizing effect for hepatocellular carcinoma cell line BEL-7404 treated with doxorubicin. This might provide a new target for clinical treatment of hepatic carcinoma
Temperature-dependent release of ATP from human erythrocytes: Mechanism for the control of local tissue perfusion
Copyright @ 2012 The AuthorsThis article has been made available through the Brunel Open Access Publishing Fund.Human limb muscle and skin blood flow increases significantly with elevations in temperature, possibly through physiological processes that involve temperature-sensitive regulatory mechanisms. Here we tested the hypothesis that the release of the vasodilator ATP from human erythrocytes is sensitive to physiological increases in temperature both in vitro and in vivo, and examined potential channel/transporters involved. To investigate the source of ATP release, whole blood, red blood cells (RBCs), plasma and serum were heated in vitro to 33, 36, 39 and 42Ā°C. In vitro heating augmented plasma or ābathing solutionā ATP in whole blood and RBC samples, but not in either isolated plasma or serum samples. Heat-induced ATP release was blocked by niflumic acid and glibenclamide, but was not affected by inhibitors of nucleoside transport or anion exchange. Heating blood to 42Ā°C enhanced (P < 0.05) membrane protein abundance of cystic fibrosis transmembrane conductance regulator (CFTR) in RBCs. In a parallel in vivo study in humans exposed to whole-body heating at rest and during exercise, increases in muscle temperature from 35 to 40Ā°C correlated strongly with elevations in arterial plasma ATP (r2 = 0.91; P = 0.0001), but not with femoral venous plasma ATP (r2 = 0.61; P = 0.14). In vitro, however, the increase in ATP release from RBCs was similar in arterial and venous samples heated to 39Ā°C. Our findings demonstrate that erythrocyte ATP release is sensitive to physiological increases in temperature, possibly via activation of CFTR-like channels, and suggest that temperature-dependent release of ATP from erythrocytes might be an important mechanism regulating human limb muscle and skin perfusion in conditions that alter blood and tissue temperature.This article is made available through the Brunel Open Access Publishing Fund
Generic two-phase coexistence in nonequilibrium systems
Gibbs' phase rule states that two-phase coexistence of a single-component
system, characterized by an n-dimensional parameter-space, may occur in an
n-1-dimensional region. For example, the two equilibrium phases of the Ising
model coexist on a line in the temperature-magnetic-field phase diagram.
Nonequilibrium systems may violate this rule and several models, where phase
coexistence occurs over a finite (n-dimensional) region of the parameter space,
have been reported. The first example of this behaviour was found in Toom's
model [Toom,Geoff,GG], that exhibits generic bistability, i.e. two-phase
coexistence over a finite region of its two-dimensional parameter space (see
Section 1). In addition to its interest as a genuine nonequilibrium property,
generic multistability, defined as a generalization of bistability, is both of
practical and theoretical relevance. In particular, it has been used recently
to argue that some complex structures appearing in nature could be truly stable
rather than metastable (with important applications in theoretical biology),
and as the theoretical basis for an error-correction method in computer science
(see [GG,Gacs] for an illuminating and pedagogical discussion of these ideas).Comment: 7 pages, 6 figures, to appear in Eur. Phys. J. B, svjour.cls and
svepj.clo neede
Identification of gene expression logical invariants in Arabidopsis.
Numerous gene expression datasets from diverse tissue samples from the plant variety Arabidopsis thaliana have been already deposited in the public domain. There have been several attempts to do large scale meta-analyses of all of these datasets. Most of these analyses summarize pairwise gene expression relationships using correlation, or identify differentially expressed genes in two conditions. We propose here a new large scale meta-analysis of the publicly available Arabidopsis datasets to identify Boolean logical relationships between genes. Boolean logic is a branch of mathematics that deals with two possible values. In the context of gene expression datasets we use qualitative high and low expression values. A strong logical relationship between genes emerges if at least one of the quadrants is sparsely populated. We pointed out serious issues in the data normalization steps widely accepted and published recently in this context. We put together a web resource where gene expression relationships can be explored online which helps visualize the logical relationships between genes. We believe that this website will be useful in identifying important genes in different biological context. The web link is http://hegemon.ucsd.edu/plant/
Video Infringement Detection via Feature Disentanglement and Mutual Information Maximization
The self-media era provides us tremendous high quality videos. Unfortunately,
frequent video copyright infringements are now seriously damaging the interests
and enthusiasm of video creators. Identifying infringing videos is therefore a
compelling task. Current state-of-the-art methods tend to simply feed
high-dimensional mixed video features into deep neural networks and count on
the networks to extract useful representations. Despite its simplicity, this
paradigm heavily relies on the original entangled features and lacks
constraints guaranteeing that useful task-relevant semantics are extracted from
the features.
In this paper, we seek to tackle the above challenges from two aspects: (1)
We propose to disentangle an original high-dimensional feature into multiple
sub-features, explicitly disentangling the feature into exclusive
lower-dimensional components. We expect the sub-features to encode
non-overlapping semantics of the original feature and remove redundant
information.
(2) On top of the disentangled sub-features, we further learn an auxiliary
feature to enhance the sub-features. We theoretically analyzed the mutual
information between the label and the disentangled features, arriving at a loss
that maximizes the extraction of task-relevant information from the original
feature.
Extensive experiments on two large-scale benchmark datasets (i.e., SVD and
VCSL) demonstrate that our method achieves 90.1% TOP-100 mAP on the large-scale
SVD dataset and also sets the new state-of-the-art on the VCSL benchmark
dataset. Our code and model have been released at
https://github.com/yyyooooo/DMI/, hoping to contribute to the community.Comment: This paper is accepted by ACM MM 202
Coronatine-insensitive 1 (COI1) mediates transcriptional responses of <i>Arabidopsis thaliana</i> to external potassium supply
The ability to adjust growth and development to the availability of mineral nutrients in the soil is an essential life skill of plants but the underlying signaling pathways are poorly understood. In <i>Arabidopsis thaliana</i>, shortage of potassium (K) induces a number of genes related to the phytohormone jasmonic acid (JA). Using comparative microarray analysis of wild-type and coi1-16 mutant plants, we classified transcriptional responses to K with respect to their dependence on COI1, a central component of oxylipin signaling. Expression profiles obtained in a short-term experiment clearly distinguished between COI1-dependent and COI1-independent K-responsive genes, and identified both known and novel targets of JA-COI1-signaling. During long-term K-deficiency, coi-16 mutants displayed de novo responses covering similar functions as COI1-targets except for defense. A putative role of JA for enhancing the defense potential of K-deficient plants was further supported by the observation that plants grown on low K were less damaged by thrips than plants grown with sufficient K
Exo70-Mediated Recruitment of Nucleoporin Nup62 at the Leading Edge of Migrating Cells is Required for Cell Migration
Nucleoporin Nup62 localizes at the central channel of the nuclear pore complex and is essential for nucleocytoplasmic transport. Through its FG-repeat domain, Nup62 regulates nuclear pore permeability and binds nuclear transport receptors. Here, we report that Nup62 interacts directly with Exo70 and colocalizes with Exo70 at the leading edge of migrating cells. Nup62 binds the N-terminal domain of Exo70 through its coiled-coil domain but not through its FG-repeat domain. Selective inhibition of leading edge Nup62 using RNA interference significantly reduces cell migration. Furthermore, Exo70 recruits Nup62 at the plasma membrane and at filopodia. Removal of the Exo70-binding domain of Nup62 prevents leading edge localization of Nup62. Analogous to Exo70, Nup62 cycles between the plasma membrane and the perinuclear recycling compartment. Altogether, we propose that Nup62 not solely regulates access to the cell nucleus, but additionally functions in conjunction with Exo70, a key regulator of exocytosis and actin dynamics, at the leading edge of migrating cells
Dynamic changes in optical and chemical properties of tar ball aerosols by atmospheric photochemical aging
Following wood pyrolysis, tar ball aerosols were laboratory generated from
wood tar separated into polar and nonpolar phases. Chemical information of
fresh tar balls was obtained from a high-resolution time-of-flight aerosol
mass spectrometer (HR-ToF-AMS) and single-particle laser desorption/resonance
enhanced multiphoton ionization mass spectrometry (SP-LD-REMPI-MS). Their
continuous refractive index (RI) between 365 and 425 nm was retrieved using
a broadband cavity enhanced spectroscopy (BBCES). Dynamic changes in the
optical and chemical properties for the nonpolar tar ball aerosols in
NOx-dependent photochemical process were investigated in an
oxidation flow reactor (OFR). Distinct differences in the chemical
composition of the fresh polar and nonpolar tar aerosols were identified.
Nonpolar tar aerosols contain predominantly high-molecular weight
unsubstituted and alkyl-substituted polycylic aromatic hydrocarbons (PAHs),
while polar tar aerosols consist of a high number of oxidized aromatic
substances (e.g., methoxy-phenols, benzenediol) with higher O : C ratios
and carbon oxidation states. Fresh tar balls have light absorption
characteristics similar to atmospheric brown carbon (BrC) aerosol with higher
absorption efficiency towards the UV wavelengths. The average retrieved RI is
1.661+0.020i and 1.635+0.003i for the nonpolar and polar tar aerosols,
respectively, with an absorption Ć
ngstrƶm exponent (AAE) between 5.7
and 7.8 in the detected wavelength range. The RI fits a volume mixing rule
for internally mixed nonpolar/polar tar balls. The RI of the tar ball
aerosols decreased with increasing wavelength under photochemical oxidation.
Photolysis by UV light (254 nm), without strong oxidants in the system,
slightly decreased the RI and increased the oxidation state of the tar balls.
Oxidation under varying OH exposure levels and in the absence of
NOx diminished the absorption (bleaching) and increased the
O : C ratio of the tar balls. The photobleaching via OH radical initiated
oxidation is mainly attributed to decomposition of chromophoric aromatics,
nitrogen-containing organics, and high-molecular weight components in the
aged particles. Photolysis of nitrous oxide (N2O) was used to
simulate NOx-dependent photochemical aging of tar balls in
the OFR. Under high-NOx conditions with similar OH exposure,
photochemical aging led to the formation of organic nitrates, and increased
both oxidation degree and light absorption for the aged tar ball aerosols.
These observations suggest that secondary organic nitrate formation
counteracts the bleaching by OH radical photooxidation to eventually regain
some absorption of the aged tar ball aerosols. The atmospheric implication
and climate effects from tar balls upon various oxidation processes are
briefly discussed.</p
Human isotypeādependent inhibitory antibody responses against Mycobacterium tuberculosis
Accumulating evidence from experimental animal models suggests that antibodies
play a protective role against tuberculosis (TB). However, little is known
about the antibodies generated upon Mycobacterium tuberculosis (MTB) exposure
in humans. Here, we performed a molecular and functional characterization of
the human Bācell response to MTB by generating recombinant monoclonal
antibodies from single isolated B cells of untreated adult patients with acute
pulmonary TB and from MTBāexposed healthcare workers. The data suggest that
the acute plasmablast response to MTB originates from reactivated memory B
cells and indicates a mucosal origin. Through functional analyses, we
identified MTB inhibitory antibodies against mycobacterial antigens including
virulence factors that play important roles in host cell infection. The
inhibitory activity of antiāMTB antibodies was directly linked to their
isotype. Monoclonal as well as purified serum IgA antibodies showed MTB
blocking activity independently of Fc alpha receptor expression, whereas IgG
antibodies promoted the host cell infection. Together, the data provide
molecular insights into the human antibody response to MTB and may thereby
facilitate the design of protective vaccination strategies
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