We present empirical metallicity-dependent calibrations of effective temperature against colours for dwarfs of luminosity classes IV and V and for giants of luminosity classes II and III, based on a ...collection from the literature of about two hundred nearby stars with direct effective temperature measurements of better than 2.5 per cent. The calibrations are valid for an effective temperature range 3100–10 000 K for dwarfs of spectral types M5 to A0 and 3100–5700 K for giants of spectral types K5 to G5. A total of 21 colours for dwarfs and 18 colours for giants of bands of four photometric systems, i.e. the Johnson (UBVR
J
I
J
JHK), the Cousins (R
C
I
C), the Sloan Digital Sky Survey (gr) and the Two Micron All Sky Survey (JHK
s), have been calibrated. Restricted by the metallicity range of the current sample, the calibrations are mainly applicable for disc stars (Fe/H ≳ − 1.0). The normalized percentage residuals of the calibrations are typically 2.0 and 1.5 per cent for dwarfs and giants, respectively. Some systematic discrepancies at various levels are found between the current scales and those available in the literature (e.g. those based on the infrared flux method or spectroscopy). Based on the current calibrations, we have re-determined the colours of the Sun. We have also investigated the systematic errors in effective temperatures yielded by the current on-going large-scale low- to intermediate-resolution stellar spectroscopic surveys. We show that the calibration of colour (g − K
s) presented in this work provides an invaluable tool for the estimation of stellar effective temperature for those on-going or upcoming surveys.
As a major component of the LAMOST Galactic surveys, the LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC) aims to survey a significant volume of the Galactic thin/thick discs and halo ...for a contiguous sky area of over 3400 deg2 centred on the Galactic anticentre (|b| ≤ 30°, 150 ≤ l ≤ 210°), and obtain λλ3700–9000 low-resolution (R ∼ 1800) spectra for a statistically complete sample of ∼3 M stars of all colours down to a limiting magnitude of r ∼ 17.8 mag (to 18.5 mag for limited fields). Together with Gaia, the LSS-GAC will yield a unique data set to advance our understanding of the structure and assemblage history of the Galaxy, in particular its disc(s). In addition to the main survey, the LSS-GAC will also target hundreds of thousands objects in the vicinity fields of M 31 and M 33 and survey a significant fraction (over a million) of randomly selected very bright stars (r ≤ 14 mag) in the Northern hemisphere. During the Pilot and the first year Regular Surveys of LAMOST, a total of 1042 586 750 867 spectra of a signal-to-noise ratio S/N(7450 Å) ≥ 10 S/N(4650 Å) ≥ 10 have been collected. In this paper, we present a detailed description of the target selection algorithm, survey design, observations and the first data release of value-added catalogues (including radial velocities, effective temperatures, surface gravities, metallicities, values of interstellar extinction, distances, proper motions and orbital parameters) of the LSS-GAC.
Glycolysis is critical for cancer stem cell reprogramming; however, the underlying regulatory mechanisms remain elusive. Here, we show that pyruvate dehydrogenase kinase 1 (PDK1) is enriched in ...breast cancer stem cells (BCSCs), whereas depletion of PDK1 remarkably diminishes ALDH
subpopulations, decreases stemness-related transcriptional factor expression, and inhibits sphere-formation ability and tumor growth. Conversely, high levels of PDK1 enhance BCSC properties and are correlated with poor overall survival. In mouse xenograft tumor, PDK1 is accumulated in hypoxic regions and activates glycolysis to promote stem-like traits. Moreover, through screening hypoxia-related long non-coding RNAs (lncRNAs) in PDK1-positive tissue, we find that lncRNA H19 is responsible for glycolysis and BCSC maintenance. Furthermore, H19 knockdown decreases PDK1 expression in hypoxia, and ablation of PDK1 counteracts H19-mediated glycolysis and self-renewal ability in vitro and in vivo. Accordingly, H19 and PDK1 expression exhibits strong correlations in primary breast carcinomas. H19 acting as a competitive endogenous RNA sequesters miRNA let-7 to release Hypoxia-inducible factor 1α, leading to an increase in PDK1 expression. Lastly, aspirin markedly attenuates glycolysis and cancer stem-like characteristics by suppressing both H19 and PDK1. Thus, these novel findings demonstrate that the glycolysis gatekeeper PDK1 has a critical role in BCSC reprogramming and provides a potential therapeutic strategy for breast malignancy.
H5N1 avian influenza virus (AIV) has emerged as a pathogenic entity for a variety of species, including humans, in recent years. Here we report an outbreak among migratory birds on Lake Qinghaihu, ...China, in May and June 2005, in which more than a thousand birds were affected. Pancreatic necrosis and abnormal neurological symptoms were the major clinical features. Sequencing of the complete genomes of four H5N1 AIV strains revealed them to be reassortants related to a peregrine falcon isolate from Hong Kong and to have known highly pathogenic characteristics. Experimental animal infections reproduced typical highly pathogenic AIV infection symptoms and pathology.
The c-Jun N-terminal kinases (JNKs) constitute one of the three major types of mitogen-activated protein kinases. Previous studies showed that JNK mediates multiple signaling transduction pathways ...implicated in cell proliferation, differentiation, inflammation, stress response and apoptosis in mammals. In the present study, we use goldfish as a model system and demonstrate that JNK kinases are necessary to promote embryonic survival and regulate eye development in vertebrates. During goldfish development, JNK1 and JNK2 are expressed at every stage from cleavage to hatching larvae. JNK3 is turned on at the gastrulation stage and then expressed at similar level to that of JNK2. JNK1 activity remains slightly fluctuated during different developmental stages. Inhibition of JNK activity caused massive apoptosis of blastula cells and significant death of goldfish embryos, which are associated with altered expression of the anti-apoptotic regulator, Mcl-1 and the proapoptotic regulator, Bak. These results provide novel information regarding the mechanisms by which JNKs promote embryonic survival. In addition, the embryos that survived inhibition of JNK activity displayed severe phenotype in the eye with clear microphthalmia and lens coloboma. To confirm that the observed phenotype is derived from JNK activity deficiency, we expressed JNK dominant negative mutant (DNM-JNK) in goldfish. Expression of DNM-JNK also caused similar phenotypes with altered expression of pax-6, Sox-2 and β-crystallin. Together, our results demonstrate that JNKs play important roles in promoting survival of vertebrate embryos and regulating development of vertebrate eye.
We re-estimate the peculiar velocity of the Sun with respect to the local standard of rest (LSR) using a sample of local stars within 600 pc of the Sun, selected from the Large Sky Area Multi-Object ...Fiber Spectroscopic Telescope (LAMOST, also named the Guoshoujing Telescope) Spectroscopic Survey of the Galactic Anti-centre (LSS-GAC). The sample consists of 94 332 FGK main-sequence stars with well-determined radial velocities and atmospheric parameters. To derive the LSR, two independent analyses are applied to the data. First, we determine the solar motion by comparing the observed velocity distribution to that generated with the analytic formulism of Schönrich & Binney that has been demonstrated to show excellent agreement with rigorous torus-based dynamics modelling by Binney & McMillan. Secondly, we propose that cold populations of thin disc stars, selected by applying an orbital eccentricity cut, can be directly used to determine the LSR without the need of asymmetric drift corrections. Both approaches yield consistent results of solar motion in the direction of Galactic rotation, V
⊙, that are much higher than the standard value adopted hitherto, derived from Strömgren's equation. The newly deduced values of V
⊙ are 1–2 km s−1 smaller than the more recent estimates derived from the Geneva–Copenhagen Survey (GCS) sample of stars in the solar neighbourhood (within 100 pc). We attribute the small difference to the presence of several well-known moving groups in the GCS sample that, fortunately, hardly affect the LSS-GAC sample. The newly derived radial (U
⊙) and vertical (W
⊙) components of the solar motion agree well with the previous studies. In addition, for all components of the solar motion, the values yielded by stars of different spectral types in the LSS-GAC sample are consistent with each other, suggesting that the local disc is well relaxed and that the LSR reported in the current work is robust. Our final recommended LSR is, (U⊙, V⊙, W⊙) = (7.01 ± 0.20, 10.13 ± 0.12, 4.95 ± 0.09) km s−1.
The amyloid-β protein (Aβ) protein plays a pivotal role in the pathogenesis of Alzheimer's disease (AD). It is believed that Aβ deposited in the brain originates from the brain tissue itself. ...However, Aβ is generated in both brain and peripheral tissues. Whether circulating Aβ contributes to brain AD-type pathologies remains largely unknown. In this study, using a model of parabiosis between APPswe/PS1dE9 transgenic AD mice and their wild-type littermates, we observed that the human Aβ originated from transgenic AD model mice entered the circulation and accumulated in the brains of wild-type mice, and formed cerebral amyloid angiopathy and Aβ plaques after a 12-month period of parabiosis. AD-type pathologies related to the Aβ accumulation including tau hyperphosphorylation, neurodegeneration, neuroinflammation and microhemorrhage were found in the brains of the parabiotic wild-type mice. More importantly, hippocampal CA1 long-term potentiation was markedly impaired in parabiotic wild-type mice. To the best of our knowledge, our study is the first to reveal that blood-derived Aβ can enter the brain, form the Aβ-related pathologies and induce functional deficits of neurons. Our study provides novel insight into AD pathogenesis and provides evidence that supports the development of therapies for AD by targeting Aβ metabolism in both the brain and the periphery.
A new methodology for ensuring that a three-coil wireless power transfer system is more energy efficient than a two-coil counterpart is presented in this paper. The theoretical proof and the ...conditions for meeting the objective are derived and practically verified in a practical prototype. The key features of the magnetic design are to: 1) shift the current stress from the primary driving circuit to the relay resonator; and 2) generate a large relay current for maximizing magnetic coupling with the receiver coil for efficient power transfer. Consequently, the current rating and cost of the driving circuit can be reduced and the overall quality factor and system energy efficiency are improved. This approach utilizes the combined advantages of the maximum efficiency principle and the use of relay resonator to overcome the energy efficiency problem for applications with extended energy transfer distances.
Abstract
This paper proposes an advanced encryption standard (AES) cryptosystem based on memristive neural network. A memristive chaotic neural network is constructed by using the nonlinear ...characteristics of a memristor. A chaotic sequence, which is sensitive to initial values and has good random characteristics, is used as the initial key of AES grouping to realize "one-time-one-secret" dynamic encryption. In addition, the Rivest-Shamir-Adleman (RSA) algorithm is applied to encrypt the initial values of the parameters of the memristive neural network. The results show that the proposed algorithm has higher security, a larger key space and stronger robustness than conventional AES. The proposed algorithm can effectively resist initial key-fixed and exhaustive attacks. Furthermore, the impact of device variability on the memristive neural network is analyzed, and a circuit architecture is proposed.
Tumor-associated macrophages (TAMs) play an essential role in metastasis. However, what enables TAMs to have a superior capacity to establish pre-metastatic microenvironment in distant organs is ...unclear. Here we have begun to uncover the effects of cytochrome P450 (CYP) 4A in TAMs on lung pre-metastatic niche formation and metastasis. CYP4A
TAM infiltration was positively associated with metastasis, pre-metastatic niche formation and poor prognosis in breast cancer patients. The pharmacological inhibition of CYP4A reduced lung pre-metastatic niche formation (evidenced by a decrease in vascular endothelial growth factor receptor 1 positive (VEGFR1
) myeloid cell recruitment and pro-metastatic protein expression) and metastatic burden, accompanied with TAM polarization away from the M2 phenotype in spontaneous metastasis models of 4T1 breast cancer and B16F10 melanoma. Co-implantation of 4T1 cells with CYP4A10
macrophages promoted lung pre-metastatic niche formation and metastasis. Depletion of TAMs disrupted lung pre-metastatic niches and thereby prevented metastasis. Treatment with the CM from CYP4A10
M2 macrophages (M2) increased pre-metastatic niche formation and metastatic burden in the lungs, whereas CYP4A inhibition attenuated these effects. In vitro TAM polarization away from the M2 phenotype induced by CYP4A inhibition decreased VEGFR1
myeloid cell migration and fibronectin expression, accompanied with downregulation of STAT3 signaling. Conversely, overexpression of CYP4A or exogenous addition of 20-hydroxyeicosatetraenoic acid promoted M2 polarization and cytokine production of macrophages and thereby enhanced migration of VEGFR1
myeloid cells, which were reversed by siRNA or pharmacological inhibition of STAT3. Importantly, a combined blocking M2 macrophage-derived factors TGF-β, VEGF and SDF-1 abolished VEGFR1
myeloid cell migration and fibroblast activation induced by CYP4A. In summary, CYP4A in TAMs is crucial for lung pre-metastatic niche formation and metastasis, and may serve as a potential therapeutic target in human cancer.
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