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Summary of a Life in Observational Ultraviolet/Optical Astronomy

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Research in Astronomy and Astrophysics 2024年第1期24卷 1-43页

作者： Donald G.york Department of Astronomy and Astrophysics The University of Chicago5801 South Ellis Ave.Chicago 60637ILUSA

I reminisce on my early life in Section 1;on my education in Sections 2.and 3.on the years at Princeton as a research astronomer in Section 4;on the years on the faculty at Chicago in Section 5;on research on Diffuse Interstellar Bands(DIBs) in Section 6;on construction of the 3.5 m telescope at Apache Point Observatory(APO)in Section 7;on work on the Sloan Digital Sky Survey(SDSS) in Section 8;on work in public education in Chicago in Section 9;and on my travels in Section 10. My main science research is of an observational nature,concerning Galactic and intergalactic interstellar gas. Highlights for me included my work on the orbiting telescope Copernicus, including the discovery of interstellar deuterium;early observations of absorption associated with fivetimes ionized oxygen;and discoveries concerning the phases of gas in the local interstellar medium, based on previously unobservable interstellar UV spectral lines. With other instruments and collaborations, I extended interstellar UV studies to the intergalactic cool gas using quasi-stellar object QSO absorption lines redshifted to the optical part of the spectrum;provided a better definition of the emission and morphological character of the source of absorption lines in QSO spectra;and pursued the identification of the unidentified DIBs. For several of these topics, extensive collaborations with many scientists were essential over many years. The conclusions developed slowly, as I moved from being a graduate student at Chicago, to a research scientist position at Princeton and then to a faculty position at Chicago. At each stage of life, I was exposed to {2. technologies adaptable to my science and to subsequent projects. From high school days, I encountered several management opportunities which were formative. I have been extremely fortunate both in scientific mentors I had and in experimental opportunities I encountered.

关键词： Interstellar Medium(ISM) Nebulae (galaxies:)quasars:absorption lines ultraviolet:stars

Mapping Problems,Fundamental Groups and Defect Measures

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Acta Mathematica Sinica,English Series 1999年第1期15卷 25-52页

作者： Fanghua LinCourant Institute of Mathematics,new york {2.,new york,ny 10012.usa Courant Institute of Mathematics New York University New York USA

We study all the possible weak limits of a minimizing sequence,for p-energy functionals, consisting of continuous maps between Riemannian manifolds subject to a Dirichlet boundary condition or a homotopy *** show that if p is not an integer,then any such weak limit is a strong limit and,in particular,a stationary p-harmonic map which is C1,α continuous away from a closed subset of the Hausdorff dimension ≤n-[p]-*** p is an integer,then any such weak limit is a weakly p-harmonic map along with a（n-p）-rectifiable Radon measure μ.Moreover,the limiting map is C1,α continuous away from a closed subset ∑=spt μ∪S with Hn-p（S）=***,we discuss the possible varifolds type theory for Sobolev mappings.

关键词： Defect measure Harmonic mapping Generalized varifold Rectifiability

Arithmetic of Shimura curves

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Science China Mathematics 2010年第3期53卷 573-592页

作者： ZHANG Shou-Wu Department of Mathematics, Columbia university, new {2., ny 1002., {{3. 1. Department of Mathematics Columbia University New York NY 10027 USA

This is the note for a series of lectures that the author gave at the Centre de Recerca Matemtica (CRM), Bellaterra, Barcelona, Spain on October 19–2., 2.09. The aim is to give a comprehensive description of some recent work of the author and his students on generalisations of the Gross-Zagier formula, Euler systems on Shimura curves, and rational points on elliptic curves.

关键词： Shimura curves CM-points L-series

Aggregation and assembly of crescent foldamers

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Science China Chemistry 2010年第1期53卷 45-51页

作者： GONG Bing Department of Chemistry,university at Buffalo,The State university of {2. {{3.,Buffalo,{2. {{3. 142.0,usa 1. Department of Chemistry University at Buffalo The State University of New York Buffalo New York 14260 USA

Recent studies have started to provide initial insights into the aggregation and assembly of two classes of back-rigidified foldamers with flat,curved backbones consisting of aromatic *** their persistent shape that presents large,well-defined aromatic surface areas,these crescent foldamers were found to undergo size-dependent aggregation in solution and pack into 1D assemblies in the solid *** aromatic oligoamides undergo stacking interactions not only in polar solvents but also in nonpolar ones,a unique property that is not associated with many other molecules that associate via π-π stacking *** stacking of oligo(m-phenylene ethynylenes) is similar to aromatic hydrocarbons,being promoted in polar solvents such as methanol while being discouraged in nonpolar solvents such as *** ready synthetic availability of crescent foldamers makes it possible to directly control the intermolecular interaction by tuning surface ***,the columnar assembly of these cavity-containing molecules provides a new strategy for constructing supramolecular nanotubular structures.

关键词： foldamer folding hydrogen bond π-π stacking aggregation assembly

Characteristics of fMRI BOLD signal and its neurophysiological mechanism

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Progress in Natural Science:Materials International 2007年第6期17卷 630-638页

作者： Zhao Xiaohu1,2. Wu Yigen3.and Guo Shengli3.1. {2. of Life Sciences, Zhejiang {3., Hangzhou 3.0058, China 2. Imaging Department of Tongji Hospital of Tongji {3., Shanghai 2.0065, China 3. {2. of Mathematics and Physics, Nanjing {3. of Information Science and Technology, Nanjing 2.0044, China) college of Life Sciences Zhejiang University Hangzhou 310058 China Imaging Department Tongji Hospital Tongji University Shanghai 200065 China college of Mathematics and Physics Nanjing University of Information Science and Technology Nanjing 210044 China

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

关键词： functional magnetic resonance imaging blood oxygen level dependent nonlinear response neural electrophysiological activity.

A new family of windows——convolution windows and their applications

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Science China(Technological Sciences) 2005年第4期48卷 468-480页

作者： ZHANG Jieqiu1,2. LIANG Changhong1 & CHEN Yanpu3.1. Department of Applied Math. & Phys., college of Science, Airforce Engineering {2., Xi’an 710051, China 2. National Key Laboratory of Antennas and Microwave Technology, Xidian {2., Xi’an 710071, China 3. Computer Center, Xi’an Communication college, Xi’an 710106, China 1. Department of Applied Math. & Phys. College of Science Airforce Engineering University 710051 Xi’an China 2. National Key Laboratory of Antennas and Microwave Technology Xidian University 710071 Xi’an China 3. Computer Center Xi’an Communication College 710106 Xi’an China

A new family of windows is constructed by convolutions via a few rectangular windows with same time width and is thus referred to as convolution windows. The expressions of the second-order up to the eighth-order convolution windows in both the time and frequency domains are derived. Their applications in high accuracy harmonic analysis of periodic signals are investigated. Comparisons between the proposed windows and some known windows with the same width shows that, when the synchronous deviation of data sampling is slight, the proposed ones have the least effect of spectral leakage. Therefore, the new windows are well suited for high accuracy harmonic analysis and parameter estimation for periodic signals. The error analysis and computer simulations show that the estimation errors, corresponding to frequency, amplitude and phase of every harmonic component of a signal, are proportional to the pth power of the relative frequency deviation in case of the pth-order convolution window is applied to windowing signal of approximately p cycles. By introducing real time adjustment in sampling interval, the proposed algorithm can adaptively trace signal frequency and lead to less sampling synchronous deviation. The proposed approach has the advantages of easy implementation and high measure precision and can be used in harmonic analysis of quasi-periodic signals whose fundamental frequency drifts slowly with time.

关键词： signal processing harmonic analysis window function convolution window synchronous error spoctral leakage

The Qa-1 Dependent CD8^+ T Cell Mediated Regulatory Pathway

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Cellular & Molecular Immunology 2005年第3期2卷 161-167页

作者： Hong Jiang~(1,2. ~1Department of Medicine,Division of Rheumatology,college of Physicians & Surgeons,Columbia university,{2. ~2.orresponding to:Dr.Hong Jiang,Department of Medicine,Division of Rheumatology,college of Physicians & Surgeons,Columbia university,63. W.168th Street,PH 8-E Ste.101,new york,ny 1003.,{2.. Department of Medicine Division of Rheumatology College of Physicians & Surgeons Columbia University New York NY 10032 USA. HJ4@columbia.edu

The immune system has evolved a variety of regulatory mechanisms to ensure the peripheral self-tolerance as well as the optimal capacity to elicit effective anti-infection immunity. At present, there is no satisfactory conceptual framework to explain how the peripheral immunity is regulated at a biological system level, which enables the immune system to perform its essential functions to mount effective immunity to virtually any foreign antigens but avoid harmful immune responses to self. In this regard, during the past few years, an “affinity/avidity model of peripheral T cell regulation” has been proposed and tested, which opens up a new paradigm to understand how the peripheral immunity, to both self and foreign antigens, is regulated. The paradigm is based on the discovery of a subset CD8^＋ T cells with TCRs which specifically recognize a unique set of self-peptides presented by the MHC class Ib molecule Qa-I differentially expressed on T cells as a function of the affinity/avidity of T cell activation. These Qa-1 restricted CD8^＋ T cells represent an example of how the immune system utilizes a unified mechanism to regulate adaptive immunity to both self and foreign antigens. Thus, by selectively down-regulating T cells of intermediate affinity/avidity, to any antigens, the immune system controls the adaptive immunity without the necessity to distinguish self from non-self in the periphery at the level of T cell regulation. Cellular ＆ Molecular Immunology. 2.05;2.{2.：161-167.

关键词： T cell regulation CD8^+ T cell affinity/avidity Qa- 1 TCR

Coating powder beds with liquids and foams based on viscous formulations using a twin screw mixer:A continuous process study

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Particuology 2024年第10期93卷 364-376页

作者： Mohamed S.Manga Dimitrios Kontziampasis Mustafa Al-Maqdad Sean Clifford Serafim Bakalis David W.york School of Chemical and Process Engineering Faculty of Engineering and Physical SciencesUniversity of LeedsLeedsLS29JTUK School of Mechanical Engineering Faculty of Engineering and Physical SciencesUniversity of LeedsLeedsLS29JTUK School of Science and Engineering University of DundeeDD14HNDundeeScotlandUK Dundee International Institute of Central South university Tongzipo RoadCentral South UniversityChangshaHunan410013China Department of Chemical Engineering School of EngineeringUniversity of NewcastleNewcastleNE17RUUK School of Chemical Engineering University of BirminghamBirminghamB152TTUK Department of Chemical Engineering Faculty of EngineeringUniversity of NottinghamNG72RDUK

Coating with viscous formulations has been essential in numerous industries as it can be a means for providing functionalization, additional properties, as well as other benefits. However, there have been scarce studies that have investigated and proposed methodologies in literature. Continuous coating of powders with viscous liquids poses as a promising technology, which has been mentioned in some studies, but has not yet been thoroughly investigated. This paper employs the use of image processing and analysis, in combination with statistical analysis of particles to evaluate the effectiveness of foams and liquids as a means of coating powder beds. Two different sizes of twin screw mixers that are working in continuous operation are employed, and a new continuous foaming device is fabricated and used for the experiments of coating. The effect of materials and process parameters (as for example rotational speed, and flowrate) on the quality of coating are investigated. Image analysis is used to assess the coating quality. The results clearly showcase the potential of using twin screw mixers for coating purposes and not only for mixing. The hypothesis that using large bubble foams to improve the coating of viscous liquids on particles is proven correct, as they provide higher quality coatings compared to their equivalent liquids, when used in the twin screw mixer. Surprisingly, using a larger scale twin screw mixer, does not show a substantial effect on the mixing, regarding quality, however there is still a requirement for mix optimization for achieving scale-up of this process. These results provide a new pathway for coating powders with viscous formulations in industrial applications, requiring less energy and effort in this process, and can pave the way towards introducing more sustainable industrial methodologies for coating.

关键词： Powder coating Continuous processing Viscous liquid Foam Image analysis Positron emission particle traking(PEPT)

Surface roughness and removal rate in magnetorheological finishing of a subsurface damage free surface

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Progress in Natural Science:Materials International 2005年第6期15卷 538-544页

作者： CHENG Haobo1*, WANG Yingwei2. FENG Zhijing1 and CHENG Kai3.1. State Key Laboratory of Tribiology, Tsinghua university, Beijing 100084, China 2. Department of Material Sciences, Changchun university of Science and Technology, Changchun 13.02., China 3. Faculty of Information and Engineering Systems, city Campus, Leeds LS1 3.E, UK) State Key Laboratory of Tribiology Tsinghua University Beijing 100084 China Department of Material Sciences Changchun University of Science and Technology Changchun 130021 China Faculty of Information and Engineering Systems City Campus Leeds LS1 3HE UK

Based on computer-controlled optical surfacing, a new technique called magnetorheological finishing (MRF), is presented. The new technique combines the features of conventional loose abrasive machining with a wheel shaped polishing tool. The tool incorporates a host of features and has unprecedented fabricating versatility. The pre-polishing and fine polishing processes can be performed only by adjusting different parameters. The material removal function is studied theoretically and the results of simulation present a Gaussian distribution feature. Based on the established theoretical model, material removal rate experiments involving a parabolic mirror are designed and carried out to determine the effect of controllable parameters on size of the gap between the workpiece and the polishing wheel, rotating speed of the polishing wheel, concentration of volume fraction of non-magnetic particles and polishing time. Further experiments are carried out on the surface microstructure of the workpiece, the final surface roughness with an initial value of 10.98 nm reaches 1.2. nm root mean square (RMS) after 2. min of polishing. The subsurface damage experiment and the atomic force microscopy (AFM) measurement on the polished surface can also verify the feasibility of the MRF technique.

关键词： magnetorheological finishing surface roughness computer controlled optical surfacing subsurface damage removal function.