Chandra and Swift X-ray Observations of the X-ray Pulsar SMC X-2 During the Outburst of 2015

We report the Chandra/HRC-S and Swift/XRT observations for the 2015 outburst of the high-mass X-ray binary pulsar in the Small Magellanic Cloud, SMC X-2. While previous studies suggested that either an O star or a Be star in the field is the high-mass companion of SMC X-2, our Chandra/HRC-S image unambiguously confirms the O-type star as the true optical counterpart. Using the Swift/XRT observations, we extracted accurate orbital parameters of the pulsar binary through a time of arrivals analysis. In addition, there were two X-ray dips near the inferior conjunction, which are possibly caused by eclipses or an ionized high-density shadow wind near the companion’s surface. Finally, we propose that an outflow driven by the radiation pressure from day ∼10 played an important role in the X-ray/optical evolution of the outburst.postprin

Swift Detection of a 65 Day X-Ray Period from the Ultraluminous Pulsar NGC 7793 P13

NGC 7793 P13 is an ultraluminous X-ray source harboring an accreting pulsar. We report on the detection of a ~65 day period X-ray modulation with Swift observations in this system. The modulation period found in the X-ray band is P = 65.05 ± 0.10 days and the profile is asymmetric with a fast rise and a slower decay. On the other hand, the u-band light curve collected by Swift UVOT confirmed an optical modulation with a period of P = 64.24 ± 0.13 days. We explored the phase evolution of the X-ray and optical periodicities and propose two solutions. A superorbital modulation with a period of ~2700–4700 days probably caused by the precession of a warped accretion disk is necessary to interpret the phase drift of the optical data. We further discuss the implication if this ~65 day periodicity is caused by the superorbital modulation. Estimated from the relationship between the spin-orbital and orbital-superorbital periods of known disk-fed high-mass X-ray binaries, the orbital period of P13 is roughly estimated as 3–7 days. In this case, an unknown mechanism with a much longer timescale is needed to interpret the phase drift. Further studies on the stability of these two periodicities with a long-term monitoring could help us to probe their physical origins.postprin

MicroRNA-375 inhibits tumour growth and metastasis in oesophageal squamous cell carcinoma through repressing insulin-like growth factor 1 receptor

Background: To understand the involvement of micro- RNA (miRNA) in the development and progression of oesophageal squamous cell carcinoma (ESCC), miRNA profiles were compared between tumour and corresponding non-tumour tissues. Methods: miRCURY LNA array was used to generate miRNA expressing profile. Real-time quantitative PCR was applied to detectthe expression of miR-375 in ESCC samples and its correlation with insulin-like growth factor 1 receptor (IGF1R). Methylation-specific PCR was used to study the methylation status in the promoter region of miR-375. The tumour-suppressive effect of miR-375 was determined by both in-vitro and in-vivo assays. Results: The downregulation of miR-375 was frequently detected in primary ESCC, which was significantly correlated with advanced stage (p=0.003), distant metastasis (p<0.0001), poor overall survival (p=0.048) and disease-free survival (p=0.0006). Promoter methylation of miR-375 was detected in 26 of 45 (57.8%) ESCC specimens. Functional assays demonstrated that miR-375 could inhibit clonogenicity, cell motility, cell proliferation, tumour formation and metastasis in mice. Further study showed that miR-375 could interact with the 39-untranslated region of IGF1R and downregulate its expression. In clinical specimens, the expression of IGF1R was also negatively correlated with miR-375 expression (p=0.008). Conclusions: This study demonstrates that miR-375 has a strong tumour-suppressive effect through inhibiting the expression of IGF1R. The downregulation of miR-375, which is mainly caused by promoter methylation, is one of the molecular mechanisms involved in the development and progression of ESCC.published_or_final_versio

Loss of APD1 in Yeast Confers Hydroxyurea Sensitivity Suppressed by Yap1p Transcription Factor

Ferredoxins are iron-sulfur proteins that play important roles in electron transport and redox homeostasis. Yeast Apd1p is a novel member of the family of thioredoxin-like ferredoxins. In this study, we characterized the hydroxyurea (HU)-hypersensitive phenotype of apd1Δ cells. HU is an inhibitor of DNA synthesis, a cellular stressor and an anticancer agent. Although the loss of APD1 did not influence cell proliferation or cell cycle progression, it resulted in HU sensitivity. This sensitivity was reverted in the presence of antioxidant N-acetyl-cysteine, implicating a role for intracellular redox. Mutation of the iron-binding motifs in Apd1p abrogated its ability to rescue HU sensitivity in apd1Δ cells. The iron-binding activity of Apd1p was verified by a color assay. By mass spectrometry two irons were found to be incorporated into one Apd1p protein molecule. Surprisingly, ribonucleotide reductase genes were not induced in apd1Δ cells and the HU sensitivity was unaffected when dNTP production was boosted. A suppressor screen was performed and the expression of stress-regulated transcription factor Yap1p was found to effectively rescue the HU sensitivity in apd1Δ cells. Taken together, our work identified Apd1p as a new ferredoxin which serves critical roles in cellular defense against HU.published_or_final_versio

Exploring the Intrabinary Shock from the Redback Millisecond Pulsar PSR J2129-0429

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Wnt2 secreted by tumour fibroblasts promotes tumour progression in oesophageal cancer by activation of the Wnt/β-catenin signalling pathway

Objectives: Interaction between neoplastic and stromal cells plays an important role in tumour progression. It was recently found that WNT2 was frequently overexpressed in fibroblasts isolated from tumour tissue tumour fibroblasts (TF) compared with fibroblasts from non-tumour tissue normal fibroblasts in oesophageal squamous cell carcinoma (OSCC). This study aimed to investigate the effect of TF-secreted Wnt2 in OSCC development via the tumour - stroma interaction. Methods: Quantitative PCR, western blotting, immunohistochemistry and immunofluorescence were used to study the expression pattern of Wnt2 and its effect on the Wnt/β-catenin pathway. A Wnt2-secreting system was established in Chinese hamster ovary cells and its conditioned medium was used to study the role of Wnt2 in cell proliferation and invasion. Results: Expression of Wnt2 could only be detected in TF but not in OSCC cancer cell lines. In OSCC tissues, Wnt2 (+) cells were mainly detected in the boundary between stroma and tumour tissue or scattered within tumour tissue. In this study, Wnt2-positive OSCC was defined when five or more Wnt2(+) cells were observed in 2003X microscopy field. Interestingly, Wnt2-positive OSCC (22/51 cases) was significantly associated with lymph node metastases (p=0.001), advanced TNM stage (p=0.001) and disease-specific survival (p<0.0001). Functional study demonstrated that secreted Wnt2 could promote oesophageal cancer cell growth by activating the Wnt/β-catenin signalling pathway and subsequently upregulated cyclin D1 and c-myc expression. Further study found that Wnt2 could enhance cell motility and invasiveness by inducing epithelial-mesenchymal transition. Conclusions: TF-secreted Wnt2 acts as a growth and invasion-promoting factor through activating the canonical Wnt/β-catenin signalling pathway in oesophageal cancer cells.published_or_final_versio

Charring rate for fire exposed X-Lam

Design of timber structures has been outlined in Eurocode 5. Notional charring rate for softwood and hardwood timber is given. For the performance of X-LAM panels in fire, only little information on charring is available and whether the fire behaviour of X-LAM is similar to homogenous timber panels has not yet been systematically analysed. This paper presents an overview of fire performance of X-LAM and evaluation of its resistance to elevated temperature as an element of structure in comparison to homogeneous timber panels. Numerical study has been carried out based on available experimental results. Charring rates for X-LAM panels obtained from experimental results are compared with those obtained from Eurocode 5 and proposed simplified model

MULTI-WAVELENGTH EMISSIONS FROM THE MILLISECOND PULSAR BINARY PSR J1023+0038 DURING AN ACCRETION ACTIVE STATE

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Discovery of an X-ray Emitting Contact Binary System 2MASS J11201034-2201340

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Searches for Millisecond Pulsar Candidates among the Unidentified <i>Fermi</i> Objects

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