Xuewu Wang

TYPE Iax SUPERNOVAE: A NEW CLASS OF STELLAR EXPLOSION*

We describe observed properties of the Type Iax class of supernovae (SNe Iax), consisting of SNe observationally similar to its prototypical member, SN 2002cx. The class currently has 25 members, and we present optical photometry and/or optical spectroscopy for most of them. SNe Iax are spectroscopically similar to SNe Ia, but have lower maximum-light velocities (2000 . |v| . 8000 kms −1 ), typically lower peak magnitudes ( 14.2 � MV,peak & 18.9 mag), and most have hot photospheres. Relative to SNe Ia, SNe Iax have low luminosities for their light-curve shape. There is a correlation between luminosity and light-curve shape, similar to that of SNe Ia, but offset from that of SNe Ia and with larger scatter. Despite a host-galaxy morphology distribution that is highly skewed to late-type galaxies without any SNe Iax discovered in elliptical galaxies, there are several indications that the progenitor stars are white dwarfs (WDs): evidence of C/O burning in their maximum-light spectra, low (typically �0.5 M⊙) ejecta masses, strong Fe lines in their late-time spectra, a lack of X-ray detections, and deep limits on massive stars and star formation at the SN sites. However, two SNe Iax show strong He lines in their spectra. The progenitor system and explosion model that best fits all of the data is a binary system of a C/O WD that accretes matter from a He star and has a deflagration. At least some of the time, this explosion will not disrupt the WD. The small number of SNe in this class prohibit a detailed analysis of the homogeneity and heterogeneity of the entire class. We estimate that in a given volume there are 31 +1713 SNe Iax for every 100 SNe Ia, and for every 1 M⊙ of iron generated by SNe Ia at z = 0, SNe Iax generate �0.036 M⊙. Being the largest class of peculiar SNe, thousands of SNe Iax will be discovered by LSST. Future detailed observations of SNe Iax should further our understanding of both their progenitor systems and explosions as well as those of SNe Ia. Subject headings: supernovae: general — supernovae: individual (SN 1991bj, SN 1999ax, SN 2002bp, SN 2002cx, SN 2003gq, SN 2004cs, SN 2004gw, SN 2005P, SN 2005cc, SN 2005hk, SN 2006hn, SN 2007J, SN 2007ie, SN 2007qd, SN 2008A, SN 2008ae, SN 2008ge, SN 2008ha, SN 2009J, SN 2009ku, SN 2010ae, SN 2010el, SN 2011ay, SN 2011ce, SN 2012Z)

Perspectives of a mid-rapidity dimuon program at the RHIC: a novel and compact muon telescope detector

Perspectives of a mid-rapidity dimuon program at the RHIC: a novel and compact muon telescope detector L Ruan 1 , G Lin 2 , Z Xu 1 , K Asselta 1 , H F Chen 3 , W Christie 1 , H J Crawford 4 , J Engelage 4 , G Eppley 5 , T J Hallman 1 , C Li 3 , J Liu 5 , W J Llope 5 , R Majka 2 , T Nussbaum 5 , J Scheblein 1 , M Shao 3 , R Soja 1 , Y Sun 3 , Z Tang 3 , X Wang 6 and Y Wang 6 July 17, 2009 This work was supported by the Director, Office of Science, Office of Nuclear Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

A Novel Planar Switched Parasitic Array Antenna With Steered Conical Pattern

A novel planar switched parasitic array antenna has been proposed for wireless communication. Compared with conventional switched array antennas, this array antenna has more compact planar structure and steered conical elevation pattern. Simulation and measurement have been carried out to validate the design. PIN diodes and micro-controller unit (MCU) are used to implement a beam switching system. Experimental results show that this antenna has the capacity to provide beam switching.

Metabolic Syndrome: Prevalence and Risk Factors in Southern China

This was a cross-sectional study to investigate the epidemiology of metabolic syndrome and the distribution of interrelated metabolic abnormalities in different population groups in Guangdong, southern China. Individuals were recruited according to the percentage of different occupational populations in southern China. The study cohort included 1206 subjects, and the prevalence and distribution of the components of metabolic syndrome were assessed using the National Cholesterol Education Program Adult Treatment Panel III 2005 criteria. The unadjusted rate of metabolic syndrome was 26.7%, and the prevalences of hypertension and diabetes were 38.0% and 4.3% respectively. Hypertension, diabetes, metabolic syndrome, abdominal obesity, elevated blood glucose and elevated blood pressure decreased significantly with increasing levels of life stress and anxiety. The prevalence of hypertension and metabolic syndrome in southern China is very high, and early identification and treatment of at-risk individuals may help target intervention to improve future cardiovascular health.

Primary malignant melanoma of the esophagus: a study of clinical features, pathology, management and prognosis.

Primary malignant melanoma of the esophagus (PMME) is a rare disease that is characterized by aggressive invasion, early metastasis, and poor prognosis. Treatment protocols are not well-established. To understand this condition more precisely, we performed a retrospective review of eight cases of PMME diagnosed at the Thoracic Department of the Cancer Center at Sun Yat-Sen University between 1985 and 2009. Eight PMME patients (five men and three women) with a mean age of 58 years (range: 48 to 72 years) were included. Dysphagia was the most common presenting symptom. All patients underwent an Ivor-Lewis esophagogastrectomy and lymph node dissection with postoperative adjuvant chemotherapy. One patient with stage III/pT4N0M0 underwent postoperative chemotherapy plus radiotherapy. Four patients died of distant metastases. The median survival time was 28 months (range: 11 months to 6 years). Our data confirm that PMME is a highly aggressive disease with a poor prognosis. If the diagnosis is suspected or confirmed as PMME, and the patients have no distal metastases or extensive lymph node enlargement, we suggest that surgery should be the first choice of treatment. With regard to adjuvant therapy, we recommend the addition of chemotherapy. The role of radiotherapy remains questionable and requires further investigation.

New prototype multi-gap resistive plate chambers with long strips

A new kind of Multi-gap Resistive Plate Chamber (MRPC) has been built for the large-area Muon Telescope Detector (MTD) for the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). These long read-out strip Multi-gap Resistive Plate Chambers (LMRPCs) have an active area of 87.0 � 17.0 cm 2 and ten 250mm-thick gas gaps arranged as a double stack. Each read-out strip is 2.5 cm wide and 90 cm long. The signals are read-out at both ends of each strip. Cosmic ray tests indicate a time resolution of � 70 ps and a detection efficiency of greater than 95%. Beam tests performed at T963 at Fermilab indicate a time resolution of 60–70 ps and a spatial resolution of � 1 cm along the strip direction. & 2008 Elsevier B.V. All rights reserved.

Design and construction of muon tomography facility based on MRPC detector for high-Z materials detection

Muon tomography with cosmic ray muons is a novel technology for high-Z material detection. The tomographic imaging is based on multiple coulomb scattering of cosmic ray muons in matter, which requires large-scale, high-efficiency, high spatial resolution detectors for tracking of incoming and outgoing muons. From previous studies, the multi-gap resistive plate chamber (MRPC) would be an excellent and inexpensive choice for this application, which also offers the possibility of introducing energy information of muons by TOF measurement for image reconstruction of muon tomography. A prototype of muon tomography facility with 6 layers large-scale MRPC detectors has been designed and is under construction, the preliminary results of muon tomography and design details of the MRPC detectors and electronics were presented.

Our experience on management of Boerhaave's syndrome with late presentation

A retrospective review of 18 patients treated for Boerhaaves syndrome in our center from 1954 to 2006 was undertaken. The patients were divided into two groups: group 1, the time delayed before treatment was less than 24 hours; group 2, the time delayed was more than 24 hours. The time interval between perforation and the onset of treatment in group 2 was from 50 hours to 30 days. Roentgenograms of the chest and esophagogram with a water-soluble contrast medium are able to reveal the perforation in most cases, and thoracentesis or thoracic drainage after swallow methylene blue may provide help as well. Surgical intervention was adopted in all three patients in group 1 and 12 in group 2, and conservative intervention in three in group 2. In group 1, two patients recovered uneventfully, the other one developed a postoperative respiratory infection, and he recovered after the infection was controlled. The mortality in group 2 was 33.3% (5/15), and the mortality in patients with conservative intervention was 100% (3/3). Five complications occurred after surgical intervention in group 2, including four fistulae and one incision infection. In conclusion, it may be appropriate to manage patients aggressively with primary repair and adequate mediastinal and pleural drainage when patients present late. Because of the syndromes initial severity and a tendency to postoperative complications, patients should be closely monitored, and correct antibiotic therapy and adequate nutrition are very important in treatment.

A portable gas sensor based on cataluminescence

We describe a portable gas sensor based on cataluminescence. Miniaturization of the gas sensor was achieved by using a miniature photomultiplier tube, a miniature gas pump and a simple light seal. The signal to noise ratio (SNR) was considered as the evaluation criteria for the design and testing of the sensor. The main source of noise was from thermal background. Optimal working temperature and flow rate were determined experimentally from the viewpoint of improvement in SNR. A series of parameters related to analytical performance was estimated. The limitation of detection of the sensor was 7 ppm (SNR = 3) for ethanol and 10 ppm (SNR = 3) for hydrogen sulphide. Zirconia and barium carbonate were respectively selected as nano-sized catalysts for ethanol and hydrogen sulphide.

Effect of SiO2/Al2O3 Ratio on Crystallization and Dielectric Properties of Barium Strontium Titanate Glass-Ceramics

The effect of SiO2/Al2O3 ratio on crystallization and dielectric properties of barium strontium titanate (BST) glass-ceramics has been investigated by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), Raman spectrometry, and dielectric measurements. The experimental results showed that appropriate SiO2/Al2O3 ratio promoted the crystallization of a ferroelectric BST phase and improved the dielectric properties of the BST glass-ceramics. These studies revealed that the Al2O3 not only served as a network former, but also acted as a network modifier, weakening the network. Additionally, the variation of the SiO2/Al2O3 ratio significantly influenced the dielectric properties of the BST glass-ceramics.