6,442 research outputs found
Gravitational wave astronomy
Get PDFWe are entering a new era of gravitational-wave astronomy. The ground-based interferometers have reached their initial design sensitivity in the audio band. Several upper limits have been set for anticipated astrophysical sources from the science data. The advanced detectors in the US and in Europe are expected to be operational around 2015. New advanced detectors are also planned in Japan and in India. The first direct detections of gravitational waves are expected within this decade. In the meanwhile, three pulsar timing array projects are forming an international collaboration to detect gravitational waves directly in the nanoHertz range using timing data from millisecond pulsars. The first direct detection of nanoHertz gravitational waves are also expected within this decade. In this paper, we review the status of current gravitational-wave detectors, possible types of sources, observational upper limits achieved, and future prospects for direct detection of gravitational waves
sj-pdf-1-jcb-10.1177_0271678X231204426 - Supplemental material for Large-scale functional network connectivity mediates the associations between lipids metabolism and cognition in type 2 diabetes
No full textSupplemental material, sj-pdf-1-jcb-10.1177_0271678X231204426 for Large-scale functional network connectivity mediates the associations between lipids metabolism and cognition in type 2 diabetes by Wen Zhang, Linqing Fu, Yan Bi, Jiani Liu, Xin Li, Xin Zhang, Zhou Zhang, Yingwen Miao, Haiyan Cheng and Bing Zhang in Journal of Cerebral Blood Flow & Metabolism</p
A study of the long-term behavior of galactic X-ray sources with RXTE
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2001.Includes bibliographical references (p. 145-157).I have carried out several investigations of the long-term behavior of galactic X-ray sources using the 4.5-year database of the All Sky Monitor (ASM), and pointed observations made with the Proportional Counter Array (PCA) on board the Rossi X-ray Timing Explorer (RXTE). I have conducted a systematic search through the ASM data of all the 300 X-ray sources monitored for evidence of periodic behavior. Follow-up investigations are pursued on the discoveries I made in (1) the state transition and orbital modulation of the black hole candidate Cyg X-1; (2) a 4.4-d period in a previously poorly-known X-ray source X 1908+075; and (3) a 98-d period in another previously poorly known X-ray source XTE J1716-389. In Cyg X-1, I have detected its orbital period in the low-hard state but not in the high-soft state. I show that absorption of X-rays by a stellar wind from the companion star can reproduce the observed modulations in the hard state. To explain the low orbital modulation in the soft-state data, a reduction of the wind density during the soft state would be required. In addition, I have discovered an evolution of the correlation between the 1.5-12 keV X-ray count rate of Cyg X-1 and its spectral hardness during the 1996 spectral state transition. I present a quantitative study of this evolution using both the ASM and the PCA data. Implications of our findings are discussed. I have discovered a 4.4-d period in the ASM light curves of the X-ray source XTE J1716-389. I present the results of the investigations on this 98-d periodic modulation using both the ASM and the PCA data. The possible cause of this period and the nature of this system are discussed.by Linqing Wen.Ph.D
VizieR Online Data Catalog: Gravitational waves search from known PSR with LIGO (Abbott+, 2017)
No full textWe have obtained timings for 200 known pulsars. Timing was performed using the 42ft telescope and Lovell telescope at Jodrell Bank (UK), the 26m telescope at Hartebeesthoek (South Africa), the Parkes radio telescope (Australia), the Nancay Decimetric Radio Telescope (France), the Arecibo Observatory (Puerto Rico) and the Fermi Large Area Telescope (LAT). Of these, 122 have been targeted in previous campaigns (Aasi+ 2014, J/ApJ/785/119), while 78 are new to this search
Predicting hospitalization for heat-related illness at the census-tract level: Accuracy of a generic heat vulnerability index in phoenix, Arizona (USA)
No full textabstract: Background: Vulnerability mapping based on vulnerability indices is a pragmatic approach for highlighting the areas in a city where people are at the greatest risk of harm from heat, but the manner in which vulnerability is conceptualized influences the results.
Objectives: We tested a generic national heat-vulnerability index, based on a 10-variable indicator framework, using data on heat-related hospitalizations in Phoenix, Arizona. We also identified potential local risk factors not included in the generic indicators.
Methods: To evaluate the accuracy of the generic index in a city-specific context, we used factor scores, derived from a factor analysis using census tract–level characteristics, as independent variables, and heat hospitalizations (with census tracts categorized as zero-, moderate-, or highincidence) as dependent variables in a multinomial logistic regression model. We also compared the geographical differences between a vulnerability map derived from the generic index and one derived from actual heat-related hospitalizations at the census-tract scale.
Results: We found that the national-indicator framework correctly classified just over half (54%) of census tracts in Phoenix. Compared with all census tracts, high-vulnerability tracts that were misclassified by the index as zero-vulnerability tracts had higher average income and higher proportions of residents with a duration of residency < 5 years.
Conclusion: The generic indicators of vulnerability are useful, but they are sensitive to scale, measurement, and context. Decision makers need to consider the characteristics of their cities to determine how closely vulnerability maps based on generic indicators reflect actual risk of harm.Corresponding Author:
Wen-Ching Chuang
Arizona State University
[email protected]
First person – Yi-Wen Xu
No full textABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Yi-Wen Xu is the first author on ‘Maternal DCAF2 is crucial for maintenance of genome stability during the first cell cycle in mice’, published in Journal of Cell Science. Yi-Wen is a PhD student in the lab of Heng-Yu Fan at the Life Sciences Institute, Zhejiang University, China, investigating the mechanisms of mammalian germ cell development and disease models relating to the female reproductive system.</jats:p
First person – Chih-Wen Chu
No full textABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Chih-Wen Chu is the first author on ‘The Ajuba family protein Wtip regulates actomyosin contractility during vertebrate neural tube closure’, published in Journal of Cell Science. Chih-Wen is an associate scientist in the lab of Sergei Sokol at Icahn School of Medicine at Mount Sinai, New York, USA, investigating apical constriction and planar cell polarity, with a focus on protein dynamics at the cell junctions.</jats:p
Extracting Information about EMRIs using Time-Frequency Methods
Get PDFThe inspirals of stellar-mass compact objects into supermassive black holes are some of the most exciting sources of gravitational waves for LISA. Detection of these sources using fully coherent matched filtering is computationally intractable, so alternative approaches are required. In Wen & Gair (2005), we proposed a detection method based on searching for significant deviation of power density from noise in a time-frequency spectrogram of the LISA data. The performance of the algorithm was assessed in Gair & Wen (2005) using Monte-Carlo simulations on several trial waveforms and approximations to the noise statistics. We found that typical extreme mass ratio inspirals (EMRIs) could be detected at distances of up to 1-3 Gpc, depending on the source parameters. In this paper, we first give an overview of our previous work in Wen & Gair (2005) and Gair & Wen (2005), and discuss the performance of the method in a broad sense. We then introduce a decomposition method for LISA data that decodes LISA's directional sensitivity. This decomposition method could be used to improve the detection efficiency, to extract the source waveform, and to help solve the source confusion problem. Our approach to constraining EMRI parameters using the output from the time-frequency method will be outlined
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Jetting, In-Nozzle Meniscus Motion and Nozzle-Plate Flooding in An Industrial Drop-on-Demand Print Head
Get PDFThe state of the ink film at and near the nozzles of a drop-ondemand(DoD) print head during jetting has a direct impact on
printing performance and reliability. We have developed highspeed imaging apparatus and analytical techniques to investigate
the ink film dynamics on an industrial print head nozzle-plate in real-time. In addition to a direct correlation between the jet
emergence velocity and drive voltage, drive-dependent variations in the oscillation of the ink meniscus in adjacent nozzles were also observed. Using a ray-tracing model to analyze the meniscus shape, the meniscus oscillations for both printing and nonprinting nozzles were found to be complex and involve elements such as pre-oscillation and high-order surface waves. The flooding of non-firing nozzles, deliberately caused by the application of maximum drive voltage to a neighboring nozzle, has been recorded and analyzed dynamically. The build-up of fluid in an annulus around the nozzle (flooding rate) has been characterized and compared with models for the net ink flow
through the nozzle
The Menkaure Triad, Numerical Thinking, and Divine Configurations in Ancient Egypt
Get PDFAbout the Author
Formerly an undergraduate at the University of California, Los Angeles, Wen Li Teng is a transfer student at the University of Chicago. Wen Li is currently pursuing a major in History
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