Search Results - (Author, Cooperation:D. Chang)
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1Latest Papers from Table of Contents or Articles in PressStaff View
Publication Date: 2018-05-02Publisher: MDPI PublishingElectronic ISSN: 1996-1073Topics: Energy, Environment Protection, Nuclear Power EngineeringPublished by: -
2Latest Papers from Table of Contents or Articles in PressStaff View
Publication Date: 2018-05-31Publisher: American Physical Society (APS)Print ISSN: 0556-2821Electronic ISSN: 1089-4918Topics: PhysicsKeywords: Formal aspects of field theory, field theory in curved spacePublished by: -
3Latest Papers from Table of Contents or Articles in PressJames D. Chang, Ashley G. Wallace, Erin E. Foster and Sung Joon Kim
American Chemical Society (ACS)
Published 2018Staff ViewPublication Date: 2018-02-03Publisher: American Chemical Society (ACS)Print ISSN: 0006-2960Electronic ISSN: 1520-4995Topics: BiologyChemistry and PharmacologyPublished by: -
4Latest Papers from Table of Contents or Articles in PressZheng, D., Chang, S.-C., Wang, H., Fang, Y., Wang, J., Feng, C., Xie, G., Jarzembowski, E. A., Zhang, H., Wang, B.
American Association for the Advancement of Science (AAAS)
Published 2018Staff ViewPublication Date: 2018-09-06Publisher: American Association for the Advancement of Science (AAAS)Electronic ISSN: 2375-2548Topics: Natural Sciences in GeneralPublished by: -
5Latest Papers from Table of Contents or Articles in PressTan, L., Xing, D., Chang, C.-H., Li, H., Xie, X. S.
American Association for the Advancement of Science (AAAS)
Published 2018Staff ViewPublication Date: 2018-08-31Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyGeosciencesComputer ScienceMedicineNatural Sciences in GeneralPhysicsKeywords: Molecular BiologyPublished by: -
6Latest Papers from Table of Contents or Articles in PressKanno, T., Lin, W.-D., Chang, C.-L., Matzke, M., Matzke, A. J. M.
Genetics Society of America (GSA)
Published 2018Staff ViewPublication Date: 2018-03-29Publisher: Genetics Society of America (GSA)Electronic ISSN: 2160-1836Topics: BiologyPublished by: -
7Latest Papers from Table of Contents or Articles in PressJ. Wang ; J. Sun ; A. Aryal ; D. Raubenheimer ; D. Liu ; Y. Sheng ; D. Chang ; L. Shi ; J. Wu ; Z. Ma ; H. Wang ; X. Meng
American Association for the Advancement of Science (AAAS)
Published 2015Staff ViewPublication Date: 2015-02-28Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsKeywords: Animals ; China/ethnology ; Climate Change ; Conservation of Natural Resources ; Culture ; *Ethnic Groups ; Human Migration ; Humans ; Life Style/ethnology ; Population Density ; *ReindeerPublished by: -
8Latest Papers from Table of Contents or Articles in PressD. C. Martin ; M. Matuszewski ; P. Morrissey ; J. D. Neill ; A. Moore ; S. Cantalupo ; J. X. Prochaska ; D. Chang
Nature Publishing Group (NPG)
Published 2015Staff ViewPublication Date: 2015-08-08Publisher: Nature Publishing Group (NPG)Print ISSN: 0028-0836Electronic ISSN: 1476-4687Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsPublished by: -
9Latest Papers from Table of Contents or Articles in PressAkil A. Puckerin, Donald D. Chang, Zunaira Shuja, Papiya Choudhury, Joachim Scholz, Henry M. Colecraft
National Academy of Sciences
Published 2018Staff ViewPublication Date: 2018-11-21Publisher: National Academy of SciencesPrint ISSN: 0027-8424Electronic ISSN: 1091-6490Topics: BiologyMedicineNatural Sciences in GeneralPublished by: -
10Latest Papers from Table of Contents or Articles in PressW Yu, V Clericò, C Hernández Fuentevilla, X Shi, Y Jiang, D Saha, W K Lou, K Chang, D H Huang, G Gumbs, D Smirnov, C J Stanton, Z Jiang, V Bellani, Y Meziani, E Diez, W Pan, S D Hawkins and J F Klem
Institute of Physics (IOP)
Published 2018Staff ViewPublication Date: 2018-06-01Publisher: Institute of Physics (IOP)Electronic ISSN: 1367-2630Topics: PhysicsPublished by: -
11Latest Papers from Table of Contents or Articles in PressMichael J. Wishon, Alexandre Locquet, C. Y. Chang, D. Choi, and D. S. Citrin
American Physical Society (APS)
Published 2018Staff ViewPublication Date: 2018-03-29Publisher: American Physical Society (APS)Print ISSN: 1050-2947Electronic ISSN: 1094-1622Topics: PhysicsKeywords: Quantum optics, physics of lasers, nonlinear optics, classical opticsPublished by: -
12Articles: DFG German National LicensesPollack, S. A. ; Chang, D. B. ; Birnbaum, M. ; Kokta, M.
[S.l.] : American Institute of Physics (AIP)
Published 1991Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Upconversion-pumped lasing characteristics near 3 μm on the 4I11/2-4I13/2 transition of the Er3+ ion in Er:YSGG (erbium-yttrium-scandium-gallium garnet) and Er:YAG (erbium-yttrium-aluminum-garnet), laser state spectroscopy, and population kinetics, are the main subjects discussed. The wide difference in lasing patterns of both garnets can be attributed to the difference in population inversion kinetics which was studied by analyzing the rise and decay of fluorescence starting from the laser states. It is shown that the effective decay times, τ1 and τ2 of the lower and upper laser states, are changed during lasing by the nonlinear energy-transfer processes such that the resulting ratio becomes τ1/τ2〈1. In Er:YSGG this condition is established during the declining phase of the 4I11/2 population, whereas in Er:YAG it occurs only for a short time during the rising phase. Consequently Er:YAG lases in a self-terminating pulsed mode. The role of various energy-transfer processes in the upconversion-pumped population inversion kinetics is discussed and analyzed. It is experimentally shown that the lower 4I13/2 laser state in both garnets is depopulated by the cooperative energy summing due to the di- and tri-ionic interactions. Because of these interactions, the 4I11/2 and 4S3/2 states are populated with ensuing fluorescence from these states at 980 and 550 nm, respectively. The indication that the latter state is populated directly by the tri-ionic interaction, rather than via the former state by two sequential ion-pair interactions, follows from the experimental fact that the 550-nm fluorescence rises faster and reaches its maximum sooner than the 980-nm fluorescence. The previously proposed kinetic rate equations for Er:YAG and Er:YSGG were modified by adding a cubic term to represent the tri-ionic interaction. The steady-state solutions yielded approximately cubic dependence of green fluorescence intensity on the intensity of pump radiation in agreement with the experiment. These solutions also explained deviations from cubic dependence observed experimentally in several erbium-doped crystals.Type of Medium: Electronic ResourceURL: -
13Articles: DFG German National LicensesPollack, S. A. ; Chang, D. B. ; McFarlane, R. A. ; Jenssen, H.
[S.l.] : American Institute of Physics (AIP)
Published 1990Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsType of Medium: Electronic ResourceURL: -
14Articles: DFG German National LicensesStaff View
ISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: A high-current, high-energy, and long-pulse positive ion source for the KSTAR neutral beam system is being developed on the basis of proven technology. The original prototype ion source was the TFTR developed by LBNL, but the accelerator slit grid brazed with shaped molybdenum tubes was a barrier for success of the copied work. In order to cover the technical and economical problems caused by the molybdenum tubes, a new OFH copper grid with circular apertures has been designed and manufactured. Cooling circuits aligned along every line of the aperture arrays are made with the help of gun drills. The test and the first experimental results of the upgraded ion source, such as high-voltage characteristics, cooling characteristics, discharge characteristics, and first beam extraction characteristics are described. © 2002 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
15Articles: DFG German National LicensesPollack, S. A. ; Chang, D. B. ; Chudnovky, F. A. ; Khakhaev, I. A.
[S.l.] : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Passive Q switching of an Er:glass laser with the pulse width varying between 14 and 80 ns has been demonstrated, using three resonator vanadium-dioxide-coated (VO2) mirror samples with temperature-dependent reflectivity and differing in the reflectivity contrast. The reflectivity changes because of a phase transition from a semiconductor to a metallic state. Broad band operating characteristics of VO2 mirrors provide Q switching over a wide range of wavelengths. In addition, mode-locked pulses with much shorter time scales have been observed, due to exciton formation and recombination. A simple criterion is derived for the allowable ambient temperatures at which the Q switching operates effectively. A simple relation has also been found relating the duration of the Q-switched pulse to the contrast in reflectivities of the two mirror phases. © 1995 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
16Articles: DFG German National LicensesChang, I. M. ; Chuo, G. S. ; Chang, D. C. ; Chen, Y. F.
[S.l.] : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Time evolution of the photoluminescence spectra of low current density electrochemically etched porous silicon are studied. When the sample is exposed to light illumination in atmosphere, the luminescence intensity decays initially. However, after a short period of degradation, it starts to enhance gradually. The profiles of the photoluminescence spectra including peak position and line width are very different for the decay and enhancement processes. When the sample is illuminated in vacuum, only a decay process is observed. Infrared spectrum shows that the hydrogen related bonding in the as-anodized sample is replaced by the oxygen related termination. A quantum confinement model together with the activity of nonradiative recombination centers is proposed to explain our observations. After oxidation under light exposure, the intensity of the photoluminescence is strong and stable. Thus, our study also provides a room temperature oxidation method for producing strong and stable luminescent porous silicon. © 1995 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
17Articles: DFG German National LicensesPollack, S. A. ; Chang, D. B. ; Birnbaum, M.
Woodbury, NY : American Institute of Physics (AIP)
Published 1989Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: Lasing action at 1.73, 1.23, and 0.85 μm was obtained by a threefold upconversion process in Er:YLF at 110 K using a 1.53 μm Er:glass pump laser. The 1.73 μm transition had the lowest threshold and highest pump conversion efficiency.Type of Medium: Electronic ResourceURL: -
18Articles: DFG German National LicensesStaff View
ISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Ion-pair upconversion pumped laser emission at 2.7–2.9 μm between the 4I11/2 and 4I13/2 excited states of triply ionized erbium ions (Er3+) has been studied at 300 and 100 K in YLF, YAG, SrF2, and CaF2 hosts. Laser action was obtained by pumping directly into the transition's terminal laser level. In all four hosts, the lifetime of the 4I13/2 state is longer than that of the 4I11/2 state, by factors of 5 and 80 for the first two, and factors of (5)/(2) and 2 for the SrF2 and CaF2, respectively. The absorption coefficient for the 1.533-μm pump radiation is comparable in YLF, SrF2, and CaF2, but is larger by a factor of 3 in YAG. At room temperature the threshold pump energy for YAG is larger by a factor of 10 than for CaF2, SrF2, and YLF. Interpretation of the lasing delay times at threshold pumping levels in terms of a simple analytic model gives for the upconversion coefficients: αYLF =1.2×10−17 cm3 s−1, αYAG =5.4×10−17 cm3 s−1, αSrF2 =2.9×10−15 cm3 s−1, and αCaF2 =3.2×10−15 cm3 s−1. Nonoptimized upconversion pumped laser efficiency in Er:YLF was measured at 110 K to be 17%. A peculiar upconversion pumped lasing behavior was observed in Er:YAG at low temperatures.Type of Medium: Electronic ResourceURL: -
19Articles: DFG German National LicensesPollack, S. A. ; Chang, D. B. ; Moise, N. L.
[S.l.] : American Institute of Physics (AIP)
Published 1986Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: A study of upconversion processes in Er3+ ions in CaF2 has led to an unambiguous demonstration of IR lasing produced by upconversion pumping alone. The study has shown: (1) strong upconversion lines originating from the 4I11/2 state; (2) the existence of both two-photon and three-photon upconversion processes; (3) an optimum concentration of 5–10 mol % for Er3+; and (4) upconversion efficiencies for the visible bands as high as 10% at 77 K and 1% at 300 K. Measurements of lasing between the 4I11/2 and 4I13/2 levels show that even though the lifetime of the upper (4I11/2) state is only half that of the lower state, self-quenching does not occur. Upconversion is implicated for this transition both by the nonpersistence of a "red shift'' during a lasing pulse, and by the opposite dependence on concentration of laser threshold energy and upconversion-produced fluorescent intensity. A simple theoretical model shows that a 2.8-μm laser operating between the 4I11/2 and 4I13/2 levels can be pumped solely by upconversion of ions in the excited 4I13/2 state produced by absorption of a 1.54-μm pulse. In addition, (1) a minimum of 1.54-μm pump energy is required; (2) lasing occurs with a delay inversely proportional to the pump energy; and (3) lasing can persist for as long as the lifetime of the lower (4I13/2) state. These predictions have been experimentally verified. The lasing experiments give a lower limit for the upconversion coefficient of α=10−16 cm3 s−1.Type of Medium: Electronic ResourceURL: -
20Articles: DFG German National LicensesChang, D. ; Phillips, I. ; Rozansky, L.
College Park, Md. : American Institute of Physics (AIP)
Published 1992Staff ViewISSN: 1089-7658Source: AIP Digital ArchiveTopics: MathematicsPhysicsNotes: Quantum superalgebras suq(m||n) are studied in the framework of R-matrix formalism. Explicit parametrization of L(+) and L(−) matrices in terms of suq(m||n) generators are presented. We also show that quantum deformation of nonsimple superalgebra su(n||n) requires its extension to u(n||n).Type of Medium: Electronic ResourceURL: