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Search Results: 1 - 10 of 96518 matches for " W. Tian "
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Hydrogen Lyman emission through the solar cycle
W. Curdt,H. Tian
Physics , 2010,
Abstract: We present observations and results of radiance and irradiance studies completed by SoHO-SUMER during the past solar cycle. We find that the cycle variation in Ly-alpha irradiance as observed by e.g. UARS-SOLSTICE can not be explained by quiet sun radiance data, and conclude that the explanation must be related to differences in the Ly-alpha radiance of various solar features and changes in their fractional distribution over the solar cycle. Consequently, we studied the emission of the hydrogen Ly-alpha line in various solar features - for the first time observed by SUMER on disk in full resolution - to investigate the imprint of the magnetic field on line profile and radiance distribution. We also compare quasi-simultaneous Ly-alpha and Ly-beta line profiles. Such high-resolution observations - not hampered by geocoronal absorption - have never been completed before.
A Josephson Junction Microscope for Low-frequency Fluctuators
L. Tian,R. W. Simmonds
Physics , 2007, DOI: 10.1103/PhysRevLett.99.137002
Abstract: The high-Q harmonic oscillator mode of a Josephson junction can be used as a novel probe of spurious two-level systems (TLSs) inside the amorphous oxide tunnel barriers of the junction. In particular, we show that spectroscopic transmission measurements of the junction resonator mode can reveal how the coupling magnitude between the junction and the TLSs varies with an external magnetic field applied in the plane of the tunnel barrier. The proposed experiments offer the possibility of clearly resolving the underlying coupling mechanism for these spurious TLSs, an important decoherence source limiting the quality of superconducting quantum devices.
Ricci Flow and the Poincare Conjecture
John W. Morgan,Gang Tian
Mathematics , 2006,
Abstract: This manuscript contains a detailed proof of the Poincare Conjecture. The arguments we present here are expanded versions of the ones given by Perelman in his three preprints posted in 2002 and 2003. This is a revised version taking in account the comments of the referees and others. It has been reformatted in the AMS book style.
High velocity HI is not associated with TeV supernova remnant W51C
W. W. Tian,D. A. Leahy
Physics , 2013, DOI: 10.1088/2041-8205/769/1/L17
Abstract: The recently-detected TeV gamma-ray source HESS J1923+141 coincides with Supernova Remnant (SNR) W51C and the star forming region W51B of the W51 complex. We construct HI absorption spectra to SNR W51C, HII regions G49.2-0.35 and G49.1-0.38 in W51B, and a nearby compact extragalactic source. Our study detects high-velocity (HV) HI clouds (above 83 km/s) which coincide with W51B, but finds that the clouds are behind W51B. Both W51C and G49.2-0.35 have have similar highest-velocity absorption features at ~70 km/s. The HII region G49.1-0.38 is behind the SNR because its HI absorption spectrum has a feature at 83 km/s. These new results argue against previous claims that the SNR has shocked the HV HI clouds. Therefore the TeV emission from the complex should not be associated with the HV HI clouds. W51C has a distance of about 4.3 kpc, smaller than the tangent point distance of 5.5 kpc in that direction, but still in the Sagittarius spiral arm.
SNR G349.7+0.2: A gamma-ray source in the far 3 kpc arm of the Galactic center
W. W. Tian,D. A Leahy
Physics , 2014, DOI: 10.1088/2041-8205/783/1/L2
Abstract: We analyze the HI absorption profile for TeV Supernova Remnant (SNR) G349.7+0.2 based on updated knowledge of the inner Galaxy's structure. We significantly revise its kinematic distance from the previous ~ 22 kpc to ~11.5 kpc, indicating it is in the far 3 kpc arm of the Galactic center. We give a revised age of ~ 1800 year for G349.7+0.2 which has a low explosion energy of ~ 2.5 x 10^50 ergs. This removes G349.7+0.2 from the set of brightest SNRs in radio, X-ray to gamma-ray wavebands and helps understand gamma-ray emission originating from this remnant better. However, one needs to use caution for old kinematic distances of Galactic objects (e.g. SNRs, Pulsars and HII regions) in the range of -12 degree =< l =< 12 degree and having distance estimates of >= 5.5 kpc.
Supernova remnant W49B and its environment
H. Zhu,W. W. Tian,P. Zuo
Physics , 2014, DOI: 10.1088/0004-637X/793/2/95
Abstract: We study Gamma-ray supernova remnant W49B and its environment using recent radio and infrared data. {\it Spitzer} IRS low resolution data of W49B shows shocked excitation lines of H$_{2}$ (0,0) S(0)-S(7) from the SNR-molecular cloud interaction. The H$_2$ gas is composed of two components with temperature of $\sim$260 K and $\sim$1060 K respectively. Various spectral lines from atomic and ionic particles are detected towards W49B. We suggest the ionic phase has an electron density of $\sim$500 cm${}^{-3}$ and a temperature of $\sim$${10^4}$ K by the spectral line diagnoses. The mid- and far-infrared data from {\it MSX}, {\it Spitzer} and {\it Herschel} reveals a 151 $\pm$ 20 K hot dust component with a mass of 7.5 $\pm$ 6.6 $\times$ ${10}^{-4} {\Msol}$ and a 45 $\pm$ 4 K warm dust component with a mass of 6.4 $\pm$ 3.2 ${\Msol}$. The hot dust is likely from materials swept up by the shock of W49B. The warm dust may possibly originate from the evaporation of clouds interacting with W49B. We build the HI absorption spectra of W49B and nearby four {\HII} regions (W49A, G42.90+0.58, G42.43-0.26 and G43.19-0.53), and study the relation between W49B and the surrounding molecular clouds by employing the 2.12 $\mu$m infrared and CO data. We therefore obtain a kinematic distance of $\sim$10 kpc for W49B and suggest that the remnant is likely associated with the CO cloud at about 40 km s$^{-1}$.
Pulsars identified from the NRAO VLA Sky Survey
J. L. Han,W. W. Tian
Physics , 1999, DOI: 10.1051/aas:1999234
Abstract: We identified 97 strong pulsars from the NRAO VLA Sky Survey (NVSS) at 1.4 GHz north of Dec(J2000) $>-40\degr$. The total flux density, linear polarization intensity and polarization angle (PA) of all pulsars are extracted from the NVSS catalog. The well-calibrated PA measurement of 5 pulsars can be used for absolute PA calibrations in other observations. Comparing the source positions with those in the pulsar catalog, we got the first measurement of the proper motion upper limit of PSR B0031-07, which is $\mu_{\alpha}\cos\delta = -102 \pm 74 mas/yr$ and $\mu_{\delta} = -105 \pm 78 mas/yr$.
Suzaku observation and distance of supernova remnant G332.5-5.6
H. Zhu,W. W. Tian,D. Wu
Physics , 2015,
Abstract: We analyze the Suzaku XIS data of the central region of supernova remnant G332.5-5.6. The X-ray data are well described by a single non-equilibrium ionization thermal model, {\tt vnei}, with an absorbing hydrogen column density of 1.4$^{+0.4}_{-0.1}$ $\times$ 10$^{21}$ cm$^{-2}$. The plasma is characterized by an electron temperature of 0.49$^{+0.08}_{-0.06}$ keV with subsolar abundances for O (0.58$^{+0.06}_{-0.05}$ solar value) and Fe (0.72$^{+0.06}_{-0.05}$ solar value) and slightly overabundance for Mg (1.23$^{+0.14}_{-0.14}$ solar value). It seems that the central X-ray emission originates from projection effect or evaporation of residual clouds inside G332.5-5.6. We estimate a distance of 3.0 $\pm$ 0.8 kpc for G332.5-5.6 based on the extinction-distance relation. G332.5-5.6 has an age of 7 - 9 kyr.
Anaesthesia Management of Caesarean Section in Two Patients with Eisenmenger's Syndrome
G. Fang,Y. K. Tian,W. Mei
Anesthesiology Research and Practice , 2011, DOI: 10.1155/2011/972671
Abstract: Recently two parturients with Eisenmenger's syndrome underwent caesarean section at our hospital. They were managed by a multidisciplinary team during their perioperative period. The caesarean sections were uneventfully performed, one under general anaesthesia and one with epidural anaesthesia, with delivery of two newborns with satisfactory Apgar scores. One patient died in the post-partum period, and the other did well. We discuss the anaesthetic considerations in managing these high-risk patients. 1. Introduction During a normal pregnancy, parturients undergo dramatic physiological changes in multiple organ systems. Changes in the cardiovascular system include decreased systemic vascular resistance (SVR), increased blood volume, and increased cardiac output (CO) secondary to increased heart rate (HR) and stroke volume (SV). Cardiac disease is a major cause of maternal death, and approximately 25% of maternal cardiac deaths in the last 30 years have been due to congenital heart disease [1]. Eisenmenger’s syndrome is classified in the high-risk category, with potentially severe cardiac and neonatal complications [2]. Eisenmenger’s syndrome is characterized by right-to-left or bidirectional shunting from severe pulmonary hypertension. Despite advances in medicine, the perioperative maternal mortality remains unacceptably high (estimated at 30%–50%) [3]. The anaesthetic management of caesarean section for parturients with Eisenmenger’s syndrome remains an anaesthetic challenge. We present our anaesthetic management of caesarean section of two recent cases. The reporting of these cases was approved by the Institutional Review Board of Tongji Medical College. 2. Case Presentation 2.1. Case 1 A 19-year-old primigravida (weight 60?kg, height 160?cm) at 33-week gestation was referred to our hospital for VSD with Eisenmenger's syndrome. A cardiac murmur was noted in childhood, but no diagnosis or treatment was performed. She had no symptoms until she developed frequent and severe nausea and vomiting during her pregnancy. Nine days prior to admission, she developed severe fatigue, progressive cough, and shortness of breath. Past medical history was significant only for penicillin allergy. Physical examination revealed cyanosis and clubbing of her fingers. Vital signs were temperature 36.8°C, heart rate (HR) 84 beats·min?1, respiratory rate (RR) 24 breaths·min?1, blood pressure (BP) 140/95?mmHg, and oxygen saturation by pulse oximetry (SpO2) 74% on 6?L·min?1 of oxygen by facemask. Auscultation revealed a loud P2 and a grade 4/6 systolic murmur at the pulmonary
Tumor necrosis factor signaling is implicated in intestinal mucosal injury of cancer cachexic mice
Jia Y, Tian W, Cui B
OncoTargets and Therapy , 2012, DOI: http://dx.doi.org/10.2147/OTT.S36119
Abstract: mor necrosis factor signaling is implicated in intestinal mucosal injury of cancer cachexic mice Original Research (862) Total Article Views Authors: Jia Y, Tian W, Cui B Published Date November 2012 Volume 2012:5 Pages 343 - 348 DOI: http://dx.doi.org/10.2147/OTT.S36119 Received: 19 July 2012 Accepted: 14 September 2012 Published: 12 November 2012 Yunhe Jia,1,* Wenjing Tian,2,* Binbin Cui1 *Jia Y and Tian W contributed equally to this work (co-first author) 1The Colorectal Cancer Surgery Department, the Third Affiliated Hospital of Harbin Medical University, Harbin, PR China; 2Department of Epidemiology, Public Health College, Harbin Medical University, Harbin, Heilongjiang Province, PR China Abstract: This study will examine the relationship between tumor necrosis factor (TNF) and intestinal mucosal injury in a cancer cachexia mouse model. The C26 adenocarcinoma cancer model was set up, and immunohistochemistry was performed to investigate the histological chances of injuring the intestinal mucosa and the intestinal villi. The liquid-phase protein chip was employed to examine the changes in TNF and its receptors. The results demonstrated an intestinal mucosal injury in the cancer cachexia mouse model. The height of the intestinal villi decreased, and thinner basal membrane thickness was noted. The serum TNF-alpha and sTNFR1 increased, while in the mucosa, the TNF-alpha concentration increased; sTNFR1 and sTNFR2 decreased when compared to the control group. In conclusion, there is a potential association between the TNF signaling pathway and the intestinal mucosal injury in a cancer cachexia mouse model. Such understanding provides insights into the development of novel therapeutic targets for intestinal mucosa protection in clinical practice.
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