11,552 research outputs found
Paradoxical effect of rapamycin on inflammatory stress-induced insulin resistance in vitro and in vivo
Insulin resistance is closely related to inflammatory stress and the mammalian target of rapamycin/S6 kinase (mTOR/S6K) pathway. The present study investigated whether rapamycin, a specific inhibitor of mTOR, ameliorates inflammatory stress-induced insulin resistance in vitro and in vivo. We used tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) stimulation in HepG2 hepatocytes, C2C12 myoblasts and 3T3-L1 adipocytes and casein injection in C57BL/6J mice to induce inflammatory stress. Our results showed that inflammatory stress impairs insulin signaling by reducing the expression of total IRS-1, p-IRS-1 (tyr632), and p-AKT (ser473); it also activates the mTOR/S6K signaling pathway both in vitro and in vivo. In vitro, rapamycin treatment reversed inflammatory cytokine-stimulated IRS-1 serine phosphorylation, increased insulin signaling to AKT and enhanced glucose utilization. In vivo, rapamycin treatment also ameliorated the impaired insulin signaling induced by inflammatory stress, but it induced pancreatic β-cell apoptosis, reduced pancreatic β-cell function and enhanced hepatic gluconeogenesis, thereby resulting in hyperglycemia and glucose intolerance in casein-injected mice. Our results indicate a paradoxical effect of rapamycin on insulin resistance between the in vitro and in vivo environments under inflammatory stress and provide additional insight into the clinical application of rapamycin
Heterogeneous mantle source and magma differentiation of quaternary arc-like volcanic rocks from Tengchong, SE margin of the Tibetan Plateau
The Tengchong volcanic field north of the Burma arc comprises numerous Quaternary volcanoes in the southeastern margin of the Tibetan Plateau. The volcanic rocks are grouped into four units (1-4) from the oldest to youngest. Units 1, 3 and 4 are composed of olivine trachybasalt, basaltic trachyandesite and trachyandesite, and Unit 2 consists of hornblende dacite. The rocks of Units 1, 3, and 4 form a generally alkaline suite in which the rocks plot along generally linear trends on Harker diagrams with only slight offset from unit to unit. They contain olivine phenocrysts with Fo values ranging from 65 to 85 mol% and have Cr-spinel with Cr# ranging from 23 to 35. All the rocks have chondrite-normalized REE patterns enriched in LREE and primitive mantle-normalized trace element patterns depleted in Ti, Nb and Ta, but they are rich in Th, Ti and P relative to typical arc volcanics. Despite minor crustal contamination, 87Sr/ 86Sr ratios (0.706-0.709), εNd values (-3.2 to -8.7), and εHf values (+4.8 to -6.4) indicate a highly heterogeneous mantle source. The Pb isotopic ratios of the lavas ( 206Pb/ 204Pb = 18.02-18.30) clearly show an EMI-type mantle source. The underlying mantle source was previously modified by subduction of the Neo-Tethyan oceanic and Indian continental lithosphere. The present heterogeneous mantle source is interpreted to have formed by variable additions of fluids and sediments derived from the subducted Indian Oceanic lithosphere, probably the Ninety East Ridge. Magma generation and emplacement was facilitated by transtensional NS-trending strike-slip faulting. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 28 May 201
High-energy scale revival and giant kink in the dispersion of a cuprate superconductor
In the present photoemission study of a cuprate superconductor
Bi1.74Pb0.38Sr1.88CuO6+delta, we discovered a large scale dispersion of the
lowest band, which unexpectedly follows the band structure calculation very
well. The incoherent nature of the spectra suggests that the hopping-dominated
dispersion occurs possibly with the assistance of local spin correlations. A
giant kink in the dispersion is observed, and the complete self-energy
containing all interaction information is extracted for a doped cuprate in the
low energy region. These results recovered significant missing pieces in our
current understanding of the electronic structure of cuprates.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Lett. on May 21, 200
Structural phase transition in IrTe: A combined study of optical spectroscopy and band structure calculations
IrPtTe is an interesting system showing competing phenomenon
between structural instability and superconductivity. Due to the large atomic
numbers of Ir and Te, the spin-orbital coupling is expected to be strong in the
system which may lead to nonconventional superconductivity. We grew single
crystal samples of this system and investigated their electronic properties. In
particular, we performed optical spectroscopic measurements, in combination
with density function calculations, on the undoped compound IrTe in an
effort to elucidate the origin of the structural phase transition at 280 K. The
measurement revealed a dramatic reconstruction of band structure and a
significant reduction of conducting carriers below the phase transition. We
elaborate that the transition is not driven by the density wave type
instability but caused by the crystal field effect which further
splits/separates the energy levels of Te (p, p) and Te p bands.Comment: 16 pages, 5 figure
Efficient and long-lived quantum memory with cold atoms inside a ring cavity
Quantum memories are regarded as one of the fundamental building blocks of
linear-optical quantum computation and long-distance quantum communication. A
long standing goal to realize scalable quantum information processing is to
build a long-lived and efficient quantum memory. There have been significant
efforts distributed towards this goal. However, either efficient but
short-lived or long-lived but inefficient quantum memories have been
demonstrated so far. Here we report a high-performance quantum memory in which
long lifetime and high retrieval efficiency meet for the first time. By placing
a ring cavity around an atomic ensemble, employing a pair of clock states,
creating a long-wavelength spin wave, and arranging the setup in the
gravitational direction, we realize a quantum memory with an intrinsic spin
wave to photon conversion efficiency of 73(2)% together with a storage lifetime
of 3.2(1) ms. This realization provides an essential tool towards scalable
linear-optical quantum information processing.Comment: 6 pages, 4 figure
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Imaging the lithosphere beneath NE Tibet: Teleseismic P and S body wave tomography incorporating surface wave starting models
The northeastern margin of the Tibetan Plateau, which includes the Qiangtang and Songpan-Ganzi terranes as well as the Kunlun Shan and the Qaidam Basin, continues to deform in response to the ongoing India–Eurasia collision. To test competing hypotheses concerning the mechanisms for this deformation, we assembled a high-quality data set of approximately 14 000 P- and 4000 S-wave arrival times from earthquakes at teleseismic distances from the International Deep Profiling of Tibet and the Himalaya, Phase IV broad-band seismometer deployments. We analyse these arrival times to determine tomographic images of P- and S-wave velocities in the upper mantle beneath this part of the plateau. To account for the effects of major heterogeneity in crustal and uppermost mantle wave velocities in Tibet, we use recent surface wave models to construct a starting model for our teleseismic body wave inversion. We compare the results from our model with those from simpler starting models, and find that while the reduction in residuals and results for deep structure are similar between models, the results for shallow structure are different. Checkerboard tests indicate that features of ~125km length scale are reliably imaged throughout the study region. Using synthetic tests, we show that the best recovery is below ~300km, and that broad variations in shallow structure can also be recovered. We also find that significant smearing can occur, especially at the edges of the model. We observe a shallow dipping seismically fast structure at depths of ~140–240km, which dies out gradually between 33°N and 35°N. Based on the lateral continuity of this structure (from the surface waves) we interpret it as Indian lithosphere. Alternatively, the entire area could be thickened by pure shear, or the northern part could be an underthrust Lhasa Terrane lithospheric slab with only the southern part from India. We see a deep fast wave velocity anomaly (below 300?km), that is consistent with receiver function observations of a thickened transition zone and could be a fragment of oceanic lithosphere. In NE Tibet, it appears to be disconnected from faster wave velocities above (i.e. it is not downwelling or subducting here). Our models corroborate results of previous work which imaged a relatively slow wave velocity region below the Kunlun Shan and northern Songpan-Ganzi Terrane, which is difficult to reconcile with the hypothesis of southward-directed continental subduction at the northern margin. Wave velocities in the shallow mantle beneath the Qaidam Basin are faster than normal, and more so in the east than the west.This work was supported by a Natural Environment Research Council studentship
(grant NE/H52449X/1)This version of record of this article can be found in Geophysical Journal International (March, 2014) 196 (3): 1724-1741. doi: 10.1093/gji/ggt47
Large-Scale Sleep Condition Analysis Using Selfies from Social Media
Sleep condition is closely related to an individual's health. Poor sleep
conditions such as sleep disorder and sleep deprivation affect one's daily
performance, and may also cause many chronic diseases. Many efforts have been
devoted to monitoring people's sleep conditions. However, traditional
methodologies require sophisticated equipment and consume a significant amount
of time. In this paper, we attempt to develop a novel way to predict
individual's sleep condition via scrutinizing facial cues as doctors would.
Rather than measuring the sleep condition directly, we measure the
sleep-deprived fatigue which indirectly reflects the sleep condition. Our
method can predict a sleep-deprived fatigue rate based on a selfie provided by
a subject. This rate is used to indicate the sleep condition. To gain deeper
insights of human sleep conditions, we collected around 100,000 faces from
selfies posted on Twitter and Instagram, and identified their age, gender, and
race using automatic algorithms. Next, we investigated the sleep condition
distributions with respect to age, gender, and race. Our study suggests among
the age groups, fatigue percentage of the 0-20 youth and adolescent group is
the highest, implying that poor sleep condition is more prevalent in this age
group. For gender, the fatigue percentage of females is higher than that of
males, implying that more females are suffering from sleep issues than males.
Among ethnic groups, the fatigue percentage in Caucasian is the highest
followed by Asian and African American.Comment: 2017 International Conference on Social Computing,
Behavioral-Cultural Modeling, & Prediction and Behavior Representation in
Modeling and Simulation (SBP-BRiMS'17
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