15,676 research outputs found
[Letter from Alex Bradford to Lieutenant and Mrs. Ray Starner - November 4, 1940]
No full textLetter from Alex Bradford to Lieutenant and Mrs. Ray Starner describing the the current state of affairs that the author was experiencing, including: the London blitz, the moral of the troops on the ground, and the collective company of men opposing the Nazi regime
Correlation of Solar X-ray Flux and SID Modified VLF Signal Strength
No full textThis paper presents a quantitative comparison of the X-ray flux during solar flares, as measured by the GOES-15 satellite, and the associated effects on the ionization levels in the lower ionosphere as measured by Sudden Ionospheric Disturbance (SID) monitors around the globe. These monitors detect signals from a variety of different transmitting stations, each sending a unique Very Low Frequency (VLF) or Low Frequency (LF) radio wave signal ranging from 16.4 to 77.5 kHz. Global signal propagation distances are achieved via the Earth-ionosphere waveguide propagation mode. During a solar flare, the increased X-ray flux enhances the ionization response in the sunlit ionosphere. The resulting SID in the lower ionosphere alters LF and VLF signal propagation. The monitored signal strength increases as a result of increased conductivity of the layer and a decrease in height of the ionosphere boundary. X-ray flux and SID modified signal strength were analyzed from March 2010 to June 2014. Ionospheric incubation times, and duration and strength of signal enhancement are related to flare strength via the X-ray flux enhancement
The student's guide to completing an author study
No full textThe 'Student's guide to completing an author study' emerged during the early development of the school library resource center program at Glen Stewart Elementary School in Stratford Canada on Prince Edward Island. This research process centered on an author study, with direct teaching and clear assignment. The resulting model has been adapted to various grade levels and subject areas in different schools.Source type: Electronic(1)http://proquest.umi.com/pqdweb?did=49237063&Fmt=7&clientId=65345&RQT=309&VName=PQ
Active X-ray optics for the next generation of X-ray space telescopes
No full textDescribed within is the design, manufacture, metrology and X-ray testing of an active X-ray
prototype intended for the next generation of X-ray telescopes. One of the challenges faced by
the X-ray telescope community is how to combine high resolution and high sensitivity into one
system, as weight limitations place constraints on the optics that can be launched. Therefore the
mandate of the active X-ray prototype is to provide high sensitivity through the ability of the optics
to be nested and to deliver high angular resolution through the active control of the optic’s form.
Piezoelectric unimorph actuators provide the active component: it is intended that they will correct
for figure errors within the optic and therefore increase the angular resolution capability.
The prototype’s design is based upon an ellipsoidal segment which provides point-to-point
focussing of an X-ray source. The prototype itself is composed of an electroformed nickel optic
where the non-reflective surface is populated with 30 piezoelectric actuators and it is the production
of the prototype that is the core of the presented research. Metrology of the actuators’ influence
functions is presented and highlight the prototype’s ability to deform its optic surface by microns.
In addition, the measured influence functions are compared against finite element models and a
distinct similarity between the functions is observed.
The prototype was tested at an X-ray beamline facility in November 2008 and the results
showed the prototype’s ability to correct the optic to achieve an improved angular resolution: from
0.786 arc-minutes to 0.686 arc-minutes in terms of full width half maximum. Finally, difficulties
in the manufacture of the prototype and X-ray testing shall be presented alongside future work in
conclusion to this thesis
Author, Geraldine Brooks at the National Library of Australia for the 2009 Ray Mathew Lecture, Canberra, 23 October 2009 [picture] /
No full textTitle from acquisitions documentation.; Part of the collection: Portraits of author, Geraldine Brooks during her visit to the National Library of Australia for the 2009 Ray Mathew Lecture, Canberra, 23 October 2009.; Acquired in digital format; access copy available online.; Mode of access: Internet via World Wide Web.; Photographed by a staff member of the National Library of Australia
Ça c'est l'amour : du film M.G.M. "les girls" / Tony Bennett, chant ; avec Neal Hefti et son orchestre. In the middle of an island / Tony Bennett, chant ; avec Ray Ellis et son orchestre. Whatever Lola wants / Tony Bennett, chant ; avec Sid Feller et son orchestre. One kiss away from heaven / Tony Bennett, chant ; avec Percy Faith et son orchestre
No full textComprend : Ça c'est l'amour / Tony Bennett, chant ; avec Neal Hefti et son orchestre ; In the middle of an island / Tony Bennett, chant ; avec Ray Ellis et son orchestre ; Whatever Lola wants / Tony Bennett, chant ; avec Sid Feller et son orchestre ; One kiss away from heaven / Tony Bennett, chant ; avec Percy Faith et son orchestreBnF-Partenariats, Collection sonore - BelieveContient une table des matière
Ray Boots, Don Simmons, John Claunch, Jim Bronstad and Sid Schmidt
No full textStarters Ray Boots, Don Simmons, John Claunch, Jim Bronstad and Sid Schmidt, left to right, have helped Paschal to unbeaten record in 4A-3 basketball race. Published in Fort Worth Star-Telegram evening January 26, 1954.https://mavmatrix.uta.edu/specialcollections_startelegram1950s/30319/thumbnail.jp
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
X-ray polarization in relativistic jets
No full textWe investigate the polarization properties of Comptonized X-rays from relativistic jets in active galactic nuclei (AGN) using Monte Carlo simulations. We consider three scenarios commonly proposed for the observed X-ray emission in AGN: Compton scattering of blackbody photons emitted from an accretion disc; scattering of cosmic microwave background (CMB) photons and self-Comptonization of intrinsically polarized synchrotron photons emitted by jet electrons. Our simulations show that for Comptonization of disc and CMB photons, the degree of polarization of the scattered photons increases with the viewing inclination angle with respect to the jet axis. In both cases, the maximum linear polarization is ≈20 per cent. In the case of synchrotron self-Comptonization (SSC), we find that the resulting X-ray polarization depends strongly on the seed synchrotron photon injection site, with typical fractional polarizations P≈ 10–20 per cent when synchrotron emission is localized near the jet base, while P≈ 20–70 per cent for the case of uniform emission throughout the jet. These results indicate that X-ray polarimetry may be capable of providing unique clues to identify the location of particle acceleration sites in relativistic jets. In particular, if synchrotron photons are emitted quasi-uniformly throughout a jet, then the observed degree of X-ray polarization may be sufficiently different for each of the competing X-ray emission mechanisms (synchrotron, SSC or external Comptonization) to determine which is the dominant process. However, X-ray polarimetry alone is unlikely to be able to distinguish between disc and CMB Comptonization
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Observations of the 57Fe+23 hyperfine transition in clusters of galaxies
No full textWe present a search for the hyperfine transition of the 57Fe+23 ion at 3.071 mm in clusters of galaxies with the ATNF Mopra telescope. The results are compared with a realistic estimate of the peak brightness temperature of the line in a cooling flow cluster A85, using the available X-ray data
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