A5077194980- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Superconducting Materials and Applications
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Geophysics and Sensor Technology
- Advanced Frequency and Time Standards
- Space Science and Extraterrestrial Life
- Asymmetric Synthesis and Catalysis
- Synthetic Organic Chemistry Methods
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Indoor Air Quality and Microbial Exposure
- Antenna Design and Optimization
- Spacecraft and Cryogenic Technologies
- Radio Wave Propagation Studies
- Odor and Emission Control Technologies
- Astronomical Observations and Instrumentation
- Cosmology and Gravitation Theories
- Bioactive Compounds and Antitumor Agents
Hessian Agency for Nature Conservation, Environment and Geology
2014-2024
Cornell University
2005-2022
Time Domain (United States)
2017
Imperial College London
2011-2014
Landesamt für Umwelt
2014
Technische Universität Braunschweig
2014
University of Bremen
2011
Philipps University of Marburg
2009-2010
Arecibo Observatory
1981-1996
National Radio Astronomy Observatory
1986-1990
view Abstract Citations (351) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Flicker of extragalactic radio sources at two frequencies. Simonetti, J. H. ; Cordes, M. Heeschen, D. S. was investigated by observing 14 flat and 20 steep spectrum 1410 2380 MHz from the Arecibo Observatory on successive days. The rms intensity variation is, average, higher than for sources. variations are shown to have contributions time scales ranging least as...
The dispersive sweep of fast radio bursts (FRBs) has been used to probe the ionized baryon content intergalactic medium, which is assumed dominate total extragalactic dispersion. While host galaxy contributions dispersion measure (DM) appear be small for most FRBs, in at least one case there evidence an extreme magneto-ionic local environment and a compact persistent source. Here we report detection localization repeating FRB 20190520B, co-located with compact, source associated dwarf high...
view Abstract Citations (257) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observational limits on the location of pulsar emission regions. Cordes, J. M. The radial locations a pulsar's region are investigated in context Radhakrishnan and Cooke's (1969) 'polar cap' or 'plasma flow' model. Corotational velocities assumed to be secondary, upper placed aberration associated with corotation. Evidence suggesting that different radio frequencies...
view Abstract Citations (165) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Pulsar timing .III. Timing noise of 50 pulsars. Cordes, J. M. ; Helfand, D. An examination the behavior pulsars has shown that activity is more than 50% correlated with pulsar period derivative, weakly period, and uncorrelated radio luminosity, galactic altitude, other source parameters. upper limit placed on for binary PSR 1913 + 16 consistent its small derivative....
view Abstract Citations (97) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Interstellar Interferometry of the Pulsar PSR 1237+25 Wolszczan, A. ; Cordes, J. M. An episode exceptionally prominent double imaging pulsar caused by refraction in interstellar medium has been detected with Arecibo telescope at 430 MHz and used to resolve magnetosphere for first time. Multiple causes quasi-periodic modulation intensity time frequency that represents...
We discuss the giant-pulse phenomenon exhibited by pulsars and distances to which giant pulses might be detected from extragalactic pulsars. describe conditions under a single-pulse search is more sensitive than standard periodicity search. find that, for certain pulse-amplitude distribution power laws time series lengths, searches can superior. present results of toward several targets, including M33, LMC (PSR B0540-69), other galaxies. While we have not conclusively any these illustrate...
view Abstract Citations (82) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Pulsar timing. I. Observations from 1970 to 1978. Helfand, D. J. ; Taylor, H. Backus, P. R. Cordes, M. The results of a series pulsar timing programs spanning eight years were presented. data have yielded accurate periods, period derivatives, and positions for three-dozen sources. Proper motions three pulsars been determined, useful upper limits derived most the...
view Abstract Citations (82) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Pulsar timing. II. Analysis of random walk timing noise : application to the Crab pulsar. Cordes, J. M. Random irregularities in rotations pulsars are analyzed by use variance rotational phase, through which consistency with data can be demonstrated and a strength parameter determined. Application Princeton optical pulsar yields 0.66 plus or minus 0.31 x 10 -22nd sq...
Einstein@Home, a distributed computing project, discovered rare, isolated pulsar with low magnetic field.
view Abstract Citations (80) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Millisecond Pulsar in a 6 Hour Orbit: PSR J0751+1807 Lundgren, S. C. ; Zepka, A. F. Cordes, J. M. 3.48 ms pulsar 6.3 hr binary orbit has been discovered systematic survey of error boxes around unidentified gamma-ray sources. The spin-down energy the is not sufficient to power estimated γ-ray emission from putative source. mass function, small orbit, low...
Telling the difference quickly: Femtosecond laser pulses are not only suitable to distinguish structural isomers. They also provide access distinction of enantiomers by combination circular dichroism and mass spectrometry [picture: see text].
view Abstract Citations (50) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The radio spectrum of micropulses from pulsar PSR 0950+08. Rickett, B. J. ; Hankins, T. H. Cordes, M. microstructure in the pulses 0950+08 has been studied over both wide and narrow frequency ranges. characterized by 0.17 ms duration are broad-band, exhibiting 50 percent correlation between 111 318 MHz. Over 125 kllz centered on MHz dynamic spectra individual show...
view Abstract Citations (48) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Pulsar timing .IV. Physical models for noise processes. Cordes, J. M. ; Greenstein, G. Eight mechanisms that have been proposed to account the process in isolated pulsars are analyzed quantitatively. Of these, it is found five face severe difficulties meeting observations. These notions arises from: (1) starquakes; (2) random pinning and unpinning of vortex lines...
A five-step synthesis of the natural product angelicoin using a late stage highly regioselective palladium(0)-catalyzed decarboxylative prenyl migration and aromatization sequence as key step is reported. The method was extended with geranyl in eight-step total syntheses hericenone J hericenol from geraniol.
Multipath propagation in the interstellar medium distorts radio pulses, an effect predominant for distant pulsars observed at low frequencies. Typically, broadened pulses are analyzed to determine amount of propagation-induced pulse broadening, but with little interest determining undistorted shapes. In this paper we develop and apply a method that recovers both intrinsic shape broadening function describes scattering impulse. The resembles CLEAN algorithm used synthesis imaging...
Fast radio bursts are a new class of transient phenomena currently detected as millisecond pulses with very high dispersion measures. As surveys begin searching for FRBs large population is expected to be in real-time, triggering range multi-wavelength and multi-messenger telescopes search repeating and/or associated emission. Here we propose method disseminating FRB triggers using Virtual Observatory Events (VOEvents). This format was developed used successfully alerts across the...
Abstract This paper describes the total synthesis of fungal natural product mycophenolic acid through palladium‐catalyzed allylation, biomimetic cyclization, and aromatization. Methyl (4 E )‐6‐hydroxy‐4‐methylhex‐4‐enoate, which was converted in four steps into key diketo ester dioxinone via two selective C ‐acylation reactions, transformed a resorcylate. Subsequent phenol methylation, lactonization, iodo‐ether formation, halogenation gave tricyclic intermediate. Palladium‐catalyzed...
view Abstract Citations (36) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Superfluid Core Rotation in Pulsars. II. Postjump Relaxations Sedrakian, A. D. ; M. Cordes, J. Terzian, Yervant A theory of nonstationary dynamics neutron star superfluid core rotation, based on the proton vortex clusters is presented. Exact solutions describing postjump relaxation component are given with allowance for spatial dependence viscous friction. In this theory,...
Average 430 MHz pulse profiles and, where possible, modulation indices and pulse-nulling fractions are computed for 28 pulsars. Morphological classifications determined most of the The authors find that core emission components tend to have lower than conal pulsars having only a component never exhibit nulling. PSR 1612+07 is shown undergo mode changes.
Abstract This paper describes the synthesis of an array 9,10‐anthraquinones 2 by initial preparation 6‐benzylresorcylates 3 from oxo‐dioxinone precursors 4 and their subsequent conversion to anthrones cyclization oxidation. Resorcylates were obtained improved two‐step procedure oxo ester 5 acyl chlorides 6 . These methods applied in a seven‐step fungal natural product macrosporin ( 1 ).
In observations of four binary millisecond pulsars with the Palomar 200 inch (5.1 m) telescope, we have detected white dwarf companions to PSR J1640+2224 and J2145-0750 placed upper limits mr = 24 25 on J0751+1807 J2229+2643. The temperature inferred for companion is T 3700 ± 300 K. luminosity a star at distance 1.2 kpc consistent that expected from (2 1) × 109 yr old helium dwarf. For J2145-0750, measured colors are inconsistent, possibly due combination emission lines in spectrum...
Intermolecular palladium(0)-catalyzed allylic alkylation of diketoester-dioxinones was performed under neutral conditions with 2-alkenyl and 2-cycloalkenyl acetates. Subsequent aromatization using cesium carbonate gave rise to isopropylidene-protected hexasubstituted resorcylates.
Very long baseline interferometry at millimetre/submillimetre wavelengths (mmVLBI) offers the highest achievable spatial resolution any wavelength in astronomy. The anticipated inclusion of ALMA as a phased array into global VLBI network will bring unprecedented sensitivity and transformational leap capabilities for mmVLBI. Building on years pioneering efforts US Europe ongoing Phasing Project (APP), US-led international collaboration with MPIfR-led European contributions, is expected to...