178,281 research outputs found
De gangbare sector als nieuwe bondgenoot ; Interview met Frank Wijnands
No full textNick van Eekeren (Louis Bolk Instituut) vindt het noodzakelijk om thema's als dierenwelzijn, huisvesting en milieu beter te combineren en te zoeken naar totaaloplossingen. Frank Wijnands (Wageningen UR) ziet kansen in onderzoek samen met de gangbare landbouw. Het zijn twee opvallende standpunten die naar voren komen tijdens een gesprek tussen de twee onderzoekers over dertig jaar onderzoek
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
On obtaining neutron star mass and radius constraints from quiescent low-mass X-ray binaries in the Galactic plane
No full textX-ray spectral analysis of quiescent low-mass X-ray binaries (LMXBs) has been one of the most common tools to measure the radius of neutron stars (NSs) for over a decade. So far, this method has been mainly applied to NSs in globular clusters, primarily because of their well-constrained distances. Here, we study Chandra data of seven transient LMXBs in the Galactic plane in quiescence to investigate the potential of constraining the radius (and mass) of the NSs inhabiting these systems. We find that only two of these objects had X-ray spectra of sufficient quality to obtain reasonable constraints on the radius, with the most stringent being an upper limit of R ≲14.5 km for EXO 0748-676 (for assumed ranges for mass and distance). Using these seven sources, we also investigate systematic biases on the mass/radius determination; for Aql X-1 we find that omitting a power-law spectral component when it does not seem to be required by the data, results in peculiar trends in the obtained radius with changing mass and distance. For EXO 0748-676 we find that a slight variation in the lower limit of the energy range chosen for the fit leads to systematically different masses and radii. Finally, we simulated Athena spectra and found that some of the biases can be lifted when higher quality spectra are available and that, in general, the search for constraints on the equation of state of ultra-dense matter via NS radius and mass measurements may receive a considerable boost in the future
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Compact objects in active galactic nuclei and X-ray binaries
No full textIn this thesis I study the inner-most regions of Active Galactic Nuclei (AGN) using
the reverberation mapping technique, and neutron star low-mass X-ray binaries in
quiescence using X-ray observations.
Using the 13-year optical monitoring data for the AGN NGC 5548, the luminosity dependence
of the Hβ emitting radius was modelled using a delay map, finding that
the radius scales with luminosity as predicted by recent theoretical models. Time-delays
between the continuum at different wavelengths in AGN can be used to probe the accretion
disc. Here, continuum time-delays in a sample of 14 AGN were used to measure the radial
temperature profile of the accretion discs, determine the nuclear extinction, and measure
distances to the objects. However, the distances measured correspond to a value for
Hubble's constant that is a factor of ~2 lower than the accepted value. The implications
of this on the thermal disc reprocessing model are discussed.
I present two Chandra observations of the neutron star transient in the globular
cluster NGC 6440 in quiescence, where the power-law component to the spectrum is seen
to be variable between the observations, suggesting that there is ongoing residual accretion.
From a Chandra observation of the globular cluster Terzan 1, I have identifed the likely
quiescent counterpart to a transient previously observed in outburst, and discuss the other
sources within the cluster. Using Chandra and XMM-Newton monitoring observations of
two neutron star transients (KS 1731-260 and MXB 1659-29) in quiescence I have found
that the neutron star crusts in both sources have now returned to thermal equilibrium
with the core. These observations also indicate that the crusts in both sources may have
a high thermal conductivity and that enhanced neutrino emission may be occurring in the
core. Finally, the discovery of an X-ray transient with XMM-Newton is presented, and the
other sources in this observation discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Boerennetwerk voor klimaatneutraal ondernemen : project doet beroep op eigen verantwoordelijkheid ondernemers (Interview met Frank Wijnands)
No full textZestien boeren, biologisch en gangbaar, gaan er de komende twee jaar alles aan doen om hun bedrijf klimaatneutraal te maken. Dit gebeurt in het netwerk BoerenKlimaat.nl dat binnenkort van start gaat
Letter from R. R. Zellick, Assistant Trust Officer, Anglo California National Bank of San Francisco, to Joseph R. Goodman, October 2, 1942
No full textLetter from R. R. Zellick, Assistant Trust Officer at The Anglo California National Bank of San Francisco, to Joseph R. Goodman, regarding property owned by Dave Tatsuno. Zellick mentions a dispute between current tenants and Tatsuno, and that Tatsuno has asked Goodman to help locate trustworthy tenants.Personal correspondence, organizational records, government documents, publications, and other papers created or collected by Joseph R. Goodman documenting the forced removal and incarceration of Japanese Americans during World War II, as well as organized resistance to incarceration. Included in the collection are records of the Japanese Young Men's Christian Association and the Japanese American Citizens' League in San Francisco, including papers of the Japanese YMCA's executive secretary Lincoln Kanai; Sakai family papers; Goodman's correspondence to and from Japanese American incarcerees, organizations opposing forced removal and incarceration of Japanese Americans, the War Relocation Authority, and others; publications, photographs, and ephemera from the Topaz Relocation Center, where Goodman taught high school; War Relocation Authority records and publications; and newspaper clippings, pamphlets, and reports about forced removal and incarceration created by various government, religious, and civic organizations, in California and nationwide
Further improved X-ray position and possible optical/nIR counterpart for XTE J1637-489
No full textWe report a further refinement of the position of the recently discovered X-ray transient XTE J1637-498 (Markwardt, Pereira and Swank, ATEL #1699). Using 1 ks of Swift XRT Photon Counting mode data and 3 Swift UVOT v band images from the observation described in Wijnands et al. (ATEL #1700), we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) of RA, Dec = 249.26112, -49.86128 deg which is equivalent to: RA (J2000): 16 37 2.67 Dec (J2000): -49 51 40.6 with an uncertainty of 1.8 arcsec (radius, 90% confidence)
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