Search Results - (Author, Cooperation:S. O'Brien)
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1Latest Papers from Table of Contents or Articles in PressSeldina, Y. I., Petro, C. D., Servetas, S. L., Vergis, J. M., Ventura, C. L., Merrell, D. S., O'Brien, A. D.
The American Society for Microbiology (ASM)
Published 2018Staff ViewPublication Date: 2018-05-23Publisher: The American Society for Microbiology (ASM)Print ISSN: 0019-9567Electronic ISSN: 1098-5522Topics: MedicinePublished by: -
2Latest Papers from Table of Contents or Articles in PressE. D. Jarvis ; S. Mirarab ; A. J. Aberer ; B. Li ; P. Houde ; C. Li ; S. Y. Ho ; B. C. Faircloth ; B. Nabholz ; J. T. Howard ; A. Suh ; C. C. Weber ; R. R. da Fonseca ; J. Li ; F. Zhang ; H. Li ; L. Zhou ; N. Narula ; L. Liu ; G. Ganapathy ; B. Boussau ; M. S. Bayzid ; V. Zavidovych ; S. Subramanian ; T. Gabaldon ; S. Capella-Gutierrez ; J. Huerta-Cepas ; B. Rekepalli ; K. Munch ; M. Schierup ; B. Lindow ; W. C. Warren ; D. Ray ; R. E. Green ; M. W. Bruford ; X. Zhan ; A. Dixon ; S. Li ; N. Li ; Y. Huang ; E. P. Derryberry ; M. F. Bertelsen ; F. H. Sheldon ; R. T. Brumfield ; C. V. Mello ; P. V. Lovell ; M. Wirthlin ; M. P. Schneider ; F. Prosdocimi ; J. A. Samaniego ; A. M. Vargas Velazquez ; A. Alfaro-Nunez ; P. F. Campos ; B. Petersen ; T. Sicheritz-Ponten ; A. Pas ; T. Bailey ; P. Scofield ; M. Bunce ; D. M. Lambert ; Q. Zhou ; P. Perelman ; A. C. Driskell ; B. Shapiro ; Z. Xiong ; Y. Zeng ; S. Liu ; Z. Li ; B. Liu ; K. Wu ; J. Xiao ; X. Yinqi ; Q. Zheng ; Y. Zhang ; H. Yang ; J. Wang ; L. Smeds ; F. E. Rheindt ; M. Braun ; J. Fjeldsa ; L. Orlando ; F. K. Barker ; K. A. Jonsson ; W. Johnson ; K. P. Koepfli ; S. O'Brien ; D. Haussler ; O. A. Ryder ; C. Rahbek ; E. Willerslev ; G. R. Graves ; T. C. Glenn ; J. McCormack ; D. Burt ; H. Ellegren ; P. Alstrom ; S. V. Edwards ; A. Stamatakis ; D. P. Mindell ; J. Cracraft ; E. L. Braun ; T. Warnow ; W. Jun ; M. T. Gilbert ; G. Zhang
American Association for the Advancement of Science (AAAS)
Published 2014Staff ViewPublication Date: 2014-12-17Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsKeywords: Animals ; Avian Proteins/genetics ; Base Sequence ; Biological Evolution ; Birds/classification/*genetics ; DNA Transposable Elements ; Genes ; Genetic Speciation ; *Genome ; INDEL Mutation ; Introns ; *Phylogeny ; Sequence Analysis, DNAPublished by: -
3Latest Papers from Table of Contents or Articles in PressEvan S. O’Brien, Jake C. Russell, Matthew Bartnof, Alexander D. Christodoulides, Kihong Lee, Jordan A. De; Gayner, Daniel W. Paley, Alan J. H. McGaughey, Wee-Liat Ong, Jonathan A. Malen, X.-Y. Zhu, Xavier Roy
American Chemical Society (ACS)
Published 2018Staff ViewPublication Date: 2018-11-13Publisher: American Chemical Society (ACS)Print ISSN: 0002-7863Electronic ISSN: 1520-5126Topics: Chemistry and PharmacologyPublished by: -
4Articles: DFG German National LicensesStaff View
ISSN: 0005-7916Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: PsychologyType of Medium: Electronic ResourceURL: -
5Articles: DFG German National LicensesO'Brien, S. ; Shealy, J. R. ; Chia, V. K. F. ; Chi, J. Y.
[S.l.] : American Institute of Physics (AIP)
Published 1990Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Substantial blue shifts in the photoluminescence (PL) transition energies of GaInAs/AlInAs single quantum wells were observed due to localized SiO2 capping and rapid thermal annealing at temperatures between 750 and 900 °C. Secondary-ion mass spectroscopy analyses show that the blue shifts are caused by the impurity-induced interdiffusion of the quantum well interfaces due to the simultaneous diffusion of silicon and oxygen into the crystal. The selective intermixing occurred in regions capped with SiO2 and exhibited blue shifts up to 74 meV while regions with no SiO2 showed only minimal shifting. With this band gap change, a lateral index change of approximately 0.6% is anticipated, making this process suitable for index-guided structures. Samples also exhibited up to 26-fold increases in PL efficiencies due to the annealing process. The dependence of energy shifts and PL efficiencies are studied by measuring room-temperature and low-temperature (≈80 K) photoluminescence. Interdiffusion coefficients have also been calculated as a function of temperature.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesO'Brien, S. ; Shealy, J. R. ; Chambers, F. A. ; Devane, G.
[S.l.] : American Institute of Physics (AIP)
Published 1992Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Impurity-free interdiffusion has been used to fabricate single mode quantum well ridge lasers from the same (Al)GaAs epitaxial material which differ in emission wavelength by as much as 11.7 nm. This represents a shift of approximately 80 laser linewidths, as measured under pulsed conditions. Threshold currents for the interdiffused and nondiffused lasers are nearly identical. However, the differential quantum efficiencies of the most interdiffused lasers are a factor of 2 lower than nondiffused lasers. The interdiffusion coefficients for the quantum well laser structure are approximately a factor of 6 smaller than those observed for intrinsic GaAs multiple quantum wells.Type of Medium: Electronic ResourceURL: -
7Articles: DFG German National LicensesStaff View
ISSN: 1089-7666Source: AIP Digital ArchiveTopics: PhysicsNotes: In rimming flow, a thin film of viscous liquid is entrained on the inside of a horizontally rotating cylinder. We give an explicit criterion for determining whether or not shock solutions occur and show that the location and height of these shocks can be determined using a simple lubrication theory. © 1998 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
8Articles: DFG German National LicensesStaff View
ISSN: 1089-7666Source: AIP Digital ArchiveTopics: PhysicsNotes: We consider steady flow of a thin viscous liquid film over a small two-dimensional topography and develop a Green's function for the linearized problem. The solutions so obtained can be used to analyze the effect of arbitrary small substrate defects on the coating applied to a substrate. © 2000 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
9Articles: DFG German National LicensesO'Brien, S. ; Shealy, J. R. ; Wicks, G. W.
Woodbury, NY : American Institute of Physics (AIP)
Published 1991Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: The monolithic integration of an intracavity modulator with a multiple quantum well (Al)GaAs laser has been accomplished with the use of selective partial interdiffusion. Interdiffusion was used to create a blue-shifted and semitransparent modulator section in a ridge laser structure. In measuring the total optical output power from the devices, steady-state extinction ratios of 20 dB were measured at reverse biases of −4.6 and −3.6 V for modulator sections with lengths of 200 and 400 μm, respectively. Shifting of the lasing mode towards longer wavelengths (Δλ≈0–50 A(ring)) was also observed making the structure useful as a tunable device and for frequency modulation applications.Type of Medium: Electronic ResourceURL: -
10Articles: DFG German National LicensesO'Brien, S. ; Bour, D. P. ; Shealy, J. R.
Woodbury, NY : American Institute of Physics (AIP)
Published 1988Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: The disordering of an ordered state of Ga0.5In0.5P and the partial intermixing of Ga0.5In0.5P/Al0.5In0.5P superlattices has been demonstrated at temperatures between 650 and 975 °C. The localized disordering or intermixing was accomplished by the deposition of SiO2 followed by rapid thermal annealing. Regions with no SiO2 showed minimal intermixing over this temperature range while the capped areas exhibited superlattice energy shifts up to 47 meV. Bulk Ga0.5In0.5P disordered at 900–925 °C for these samples with SiO2 while remaining ordered for samples with no SiO2. The degree of disordering or intermixing was measured using room-temperature and low-temperature photoluminescence and Raman spectroscopy.Type of Medium: Electronic ResourceURL: -
11Articles: DFG German National LicensesRalston, J. D. ; O'Brien, S. ; Wicks, G. W. ; Eastman, L. F.
Woodbury, NY : American Institute of Physics (AIP)
Published 1988Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: Substantial increases are observed in the energies of room-temperature exciton transitions in GaAs/AlGaAs superlattices which have been partially intermixed via the impurity-free vacancy diffusion process. Localized intermixing of the layered structure was accomplished by selective deposition of a SiO2 capping layer followed by rapid thermal annealing at temperatures between 850 and 950 °C for 15 s. In the samples studied, the above process allows continuously variable energy shifts of at least 61 meV while still maintaining clearly resolved excitonic behavior. Shifting and broadening of the exciton transitions are studied using room-temperature photoluminescence and photocurrent spectroscopies. A transmission resonance calculation is used to determine the interdiffusion coefficient as a function of temperature from the measured energy shifts.Type of Medium: Electronic ResourceURL: -
12Articles: DFG German National LicensesO'Brien, S. ; Shealy, J. R. ; Bour, D. P. ; Elbaum, L. ; Chi, J. Y.
Woodbury, NY : American Institute of Physics (AIP)
Published 1990Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: Substantial blue shifts in the transition energies of GaInAs/AlInAs single quantum wells were observed due to localized SiO2 capping and rapid thermal annealing at temperatures between 750 and 900 °C. In contrast to previously reported results, regions capped with SiO2 exhibited blue shifts up to 74 meV while regions with no SiO2 showed minimal shifting. With this band-gap change, a lateral index change of approximately −0.6% is anticipated making this process suitable for index-guided lasers. Samples also exhibited up to 15-fold increases in PL efficiencies due to the annealing process. The dependence of energy shifts and PL efficiencies is studied by measuring room-temperature and low-temperature photoluminescence.Type of Medium: Electronic ResourceURL: -
13Articles: DFG German National LicensesBhal, PS ; Pugh, N ; O'Brien, S ; Rimmington, M ; Sizer, A ; Pembridge, J ; Walker, SM ; Shaw, RW
Oxford, UK : Blackwell Publishing Ltd
Published 1998Staff ViewISSN: 1471-0528Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: MedicineType of Medium: Electronic ResourceURL: -
14Articles: DFG German National LicensesGeusic, M. E. ; Morse, M. D. ; O'Brien, S. C. ; Smalley, R. E.
[S.l.] : American Institute of Physics (AIP)
Published 1985Staff ViewISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: A new fast flow device for the study of metal cluster reactions in the gas phase is described and characterized. The new device utilizes metal clusters made by laser vaporization of an appropriate metal target mounted in the throat of a supersonic nozzle which exhausts into a fast-flow reaction tube. Reactants are injected into the flowing helium–metal cluster mixture at a point in the flow tube where shock waves have reheated the gas to roughly 320 K. Turbulence in the wake of these shock waves produces efficient mixing of the reactants. Measurement of the flow properties of this reaction tube indicate a residence time of 150–200 μs with an average density of helium buffer gas equivalent to 50–100 Torr at room temperature. Subsequent free expansion of this reaction mixture into a large vacuum chamber produces a supersonic beam with extensive cooling of the various constituents in the mixture (pyrazine was measured to be rotationally cooled to 10 K). The new cluster reaction device is, therefore, an excellent source for future studies of the jet-cooled metal cluster reaction products themselves.Type of Medium: Electronic ResourceURL: -
15Articles: DFG German National LicensesJAMES, D. ; PERALTA, B. ; PORTER, S. ; DARVILL, D. ; WALKER, J. ; McCALL, M. ; CALDER, A. ; O'BRIEN, S. ; BEVERIDGE, R. ; LIU, D. ; SHELTON, L. ; JUSTICE, T. ; STANGER, D.
Oxford, UK : Blackwell Publishing Ltd
Published 1988Staff ViewISSN: 1471-0528Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: MedicineNotes: Summary. A commercially produced domiciliary fetal monitoring (DFM) system was assessed in four centres in the UK (Bristol, Glasgow, London and Nottingham) chosen to allow for comprehensive assessment in various settings in many different women. Overall, 825 recordings were made from 368 women (2·24 per woman). There were 56 unsuccessful attempts at transmission (6·8%), most were due to problems with telephone equipment. The system worked most efficiently when a dedicated direct line was used. The data transmission time varied between 40 and 60 s. The median telephone time (including data transmission and conversation) with a dedicated direct line was 7min. Mean acceptance times from the four centres were between 70 and 80%. All recordings with acceptance times of 40% or more were interpretable. Ten recordings were abnormal. The women and midwives were equally proficient at using the DFM system. The DFM system represents an important addition to current methods of fetal assessment. Specific guidelines are outlined.Type of Medium: Electronic ResourceURL: -
16Articles: DFG German National LicensesZimmermann, C. ; Hänsch, T. W. ; Byer, R. ; O'Brien, S. ; Welch, D.
Woodbury, NY : American Institute of Physics (AIP)
Published 1992Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: We have doubled the frequency of a single mode distributed Bragg reflection (DBR) semiconductor laser. The laser is optically locked to an external enhancement ring resonator that contains an antireflection coated potassium niobate crystal. Unlike Fabry–Perot cavity lasers the DBR laser is found to operate in only one longitudinal mode and allows stable second harmonic generation. We present the results obtained with a singly and doubly resonant cavity. A total output of 1.2 mW tunable single mode radiation near 486 nm has been generated from a laser output power of 25 mW at 972 nm without the use of optical isolators or active feedback control.Type of Medium: Electronic ResourceURL: -
17Articles: DFG German National LicensesO'Brien, S. ; Mehuys, D. ; Welch, D. F. ; Parke, R. ; Scifres, D.
Woodbury, NY : American Institute of Physics (AIP)
Published 1992Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: An integrated coherent beam expander utilizing a transverse leaky mode waveguide has been integrated with a single mode distributed Bragg reflector laser and a preamplifier producing powers in excess of 70 mW cw in a single spectral and spatial mode across an aperture over 100 μm wide. The far-field pattern in the direction parallel to the plane of the p-n junction, consists of one main lobe 0.45° wide, indicating that the beam is coherent over the full emitting aperture. The expanded beam is suitable as an injection source for an integrated broad area amplifier.Type of Medium: Electronic ResourceURL: -
18Articles: DFG German National LicensesO'Brien, S. C. ; Heath, J. R. ; Curl, R. F. ; Smalley, R. E.
College Park, Md. : American Institute of Physics (AIP)
Published 1988Staff ViewISSN: 1089-7690Source: AIP Digital ArchiveTopics: PhysicsChemistry and PharmacologyNotes: The laser-induced fragmentation behavior of positive carbon cluster ions has been investigated by tandem time-of-flight techniques for the jet-cooled clusters up to 80 atoms in size. Two distinct photophysical regimes were found. The first applies to clusters with 34 atoms or more, all of which dissociate to produce even numbered fragments. Large even clusters fragment by the loss of the high energy species C2, odd ones lose a C atom. The second regime applies to clusters composed of 31 or less atoms, all of which fragment by the loss of C3. These two regimes are sharply separated by C+32 which fragments to produce small cluster ions in the 10–19 atom size range. Fragmentation of the large clusters occurs on a microsecond or faster time scale only at very high levels of excitation (〉12.8 eV). These photophysical results are interpreted as consequences of the large even clusters having edgeless, spheroidal cage structures while the small ones have linear chain or ring structures.Type of Medium: Electronic ResourceURL: -
19Articles: DFG German National LicensesHeath, J. R. ; Liu, Yuan ; O'Brien, S. C. ; Zhang, Qing-Ling ; Curl, R. F. ; Tittel, F. K. ; Smalley, R. E.
College Park, Md. : American Institute of Physics (AIP)
Published 1985Staff ViewISSN: 1089-7690Source: AIP Digital ArchiveTopics: PhysicsChemistry and PharmacologyNotes: Supersonic beams of clusters of Si and Ge atoms have been produced by laser vaporization followed by supersonic expansion in a helium carrier. The cluster beams were characterized by F2(7.9 eV) and ArF(6.4 eV) excimer laser ionization accompanied by time-of-flight mass analysis. In addition, the feasibility of a resonant two-photon ionization (R2PI) spectroscopic study was explored by two-color experiments involving initial excitation with the second (2.36 eV) and third (3.54 eV) harmonics of the Nd:YAG followed by excimer laser ionization. All two-photon ionization processes were found to produce extensive fragmentation of the larger clusters. The observed fragmentation pattern for the silicon and germanium clusters were remarkably similar to each other, but drastically different from that seen for metal clusters in the same apparatus. Unlike metal clusters, which tend to lose one atom at a time, these semiconductor clusters appear to fragment by a fission process, the daughter ions falling almost exclusively in the size range from 6 to 11 atoms. Time delay studies in the two-color experiments established that clusters of both Si and Ge have excited electronic states with lifetimes of approximately 100 ns. This again is dramatically different from the behavior found with metal clusters, and indicates the feasibility of R2PI spectroscopy on these cold semiconductor particles. The existence of such long-lived excited states indicates that there is probably an energy gap between the band of electronic states being excited and the ground electronic state.Type of Medium: Electronic ResourceURL: -
20Articles: DFG German National LicensesO'Brien, S. C. ; Liu, Y. ; Zhang, Q. ; Heath, J. R. ; Tittel, F. K. ; Curl, R. F. ; Smalley, R. E.
College Park, Md. : American Institute of Physics (AIP)
Published 1986Staff ViewISSN: 1089-7690Source: AIP Digital ArchiveTopics: PhysicsChemistry and PharmacologyNotes: Supersonic beams of semiconductor clusters with the formula GaxAsy were generated by laser vaporization of a disc of pure GaAs mounted on the side of a pulsed supersonic nozzle. These cluster beams were characterized by laser photoionization with various fixed-frequency lasers followed by time-of-flight mass spectrometry. Mass analysis of the clusters with x+y〉10 showed all clusters in the composition range from Gax+y through GaxAsy to Asx+y to be present in roughly the amount expected from a binomial distribution. In the smaller clusters strong variations were observed from this expected binomial distirbution as a result of kinetic effects in the cluster formation process. Photoionization with an ArF excimer laser at very low pulse energy revealed a pronounced even/odd alternation in the photoionization cross section of the GaxAsy clusters, depending only on the total number of atoms in the cluster. Clusters in the 5–21 atom range with an odd number of atoms were one-photon ionized by the 6.4 eV ArF excimer laser photons. This even/odd alternation in ionization properties of the clusters supports the view that the even clusters have fully paired singlet ground states with no dangling bonds. At higher ArF excimer laser fluences, the observed mass spectrum became increasingly affected by fragmentation. As is true with bulk GaAs surfaces, these GaxAsy clusters evaporate largely by the loss of arsenic (probably As2) when heated by the laser, leaving behind clusters which are richer in gallium.Type of Medium: Electronic ResourceURL: