2,342 research outputs found
Modelling the relaxation of red sprite plasma
No full textRed sprites consist of multiple ionised columns extending above a thunderstorm from ~30 km to ~90 km. Electron densities in these columns are very much larger than the ambient background, perhaps fives times at 70 km. These highly ionized structures cause observable perturbations in subionospheric VLF transmissions known as "VLF Sprites". Three models of initial sprite electron density are considered, and using a realistic ionization relaxation model the time dependence of electron density is derived. A 3-D Born propagation code of is used to compute the time profile of a VLF sprite. Two profiles show good agreement with the time signature experimentally observed, in that scattered amplitude and phase decrease linearly log(t). These simulations provide insight into the nature and structure of sprite columns, and indicate an additional constraint which should be applied to red sprite creation models
Determining the size of lightning-induced electron precipitation patches
No full text[1] We analyze Trimpi signatures during 23 and 24 April 1994 at four sites on or near the Antarctic Peninsula (Palmer, Faraday, Rothera, and Halley) on subionospheric VLF signals received from four U. S. naval transmitters (NAA, NSS, NLK, and NPM). Electron precipitation patches are found to be large, i.e., similar to1500 km x 600 km, with the longer axis orientated east-west. Calculations using a three-dimensional Born scattering model, where patch densities are 1.5 electrons cm(-3) above ambient at the center at similar to84 km altitude, provides results that are consistent with this picture. A high proportion (38%) of the Trimpi events were associated with strong lightning flashes in eastern United States. When lightning discharges had currents >65 kA (positive or negative), there was a >80% chance of seeing an associated Trimpi event. The chance of seeing any Trimpi events fell to near zero for discharges of <45 kA. The largest Trimpi perturbations occur when the center of the precipitation patch is 700-800 km from the receivers. This result is consistent with the modeling calculations for large patches. The equatorward edge of the precipitation patch was estimated to be at &SIM;60&DEG;S, close to the magnetic conjugate of the lightning. The close association of the equatorward edge of the precipitation patch with the conjugate location of the causative lightning is consistent with a quasi-ducted whistler-induced precipitation mechanism. Nonducted whistler-induced precipitation mechanisms would predict a 5&DEG;-10&DEG; latitudinal gap between the lightning and the equatorward edge of the patch. However, the lack of observed whistlers at the time of the Trimpi events is consistent with the nonducted whistler mechanism and is not consistent with the quasi-ducted mechanism, although the distances from duct exit point to receiver may have been too large (&SIM;700-1000 km) for the signals to be detectable. Using the significantly larger patch dimensions determined in this study, it is estimated that lightning may well be 10-100 times more effective at depleting the radiation belts than hiss
The Impact of PMSE on VLF Propagation
No full textABSTRACT PMSE or Polar Mesosphere Summer Echoes are a well known phenomenon in the summer northern polar regions, in which anomalous VHF/UHF radar echoes are returned from heights ~85 km. Associated phenomena at these altitudes are noctilucent clouds and electron density biteouts. The latter are electron density depletion layers of up to 90%, which may be several kms thick. Using the NOSC Modefndr code based on Wait's modal theory for subionospheric propagation, we calculate the shifts in received VLF amplitude and phase that occur as a result of electron density biteouts. The code assumes a homogeneous background ionosphere and a homogeneous biteout layer along the Great Circle Path (GCP) corridor, for transmitter receiver path lengths in the range 500-6000 km. For profiles during the 10hrs about midnight and under quiet geomagnetic conditions, where the electron density at 85 km would normally be less than 500 el/cc, it was found that received signal perturbations were significant, of the order of 1-4 dB and 5-40 degrees of phase. Perturbation amplitudes increase roughly as the square root of frequency. At short range perturbations are rather erratic, but more consistent at large ranges, readily interpretable in terms of the shifts in excitation factor, attenuation factor and v/c ratios for Wait's modes. Under these conditions such shifts should be detectable by a well constituted experiment involving multiple paths and multiple frequencies in the north polar region in summer. It is anticipated that VLF propagation could be a valuable diagnostic for biteout/PMSE when electron density at 85 km is under 500 el/cc, under which circumstances PMSE are not directly detectable by VHF/UHF radars. Keywords: 0689 Wave propagation, 2475 Polar ionosphere, 6934 Ionospheric propagation
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
Observation of psi(3686) -> e(+)e(-)chi(cJ) and chi(cJ) -> e(+)e(-)J/psi
No full textKolcu, Onur Buğra (Arel Author)Using 4.479 x 10(8) psi(3686) events collected with the BESIII detector, we search for the decays psi(3686) -> e(+)e(-)chi(cJ) and chi(cJ) -> e(+)e(-)J/psi, where J = 0, 1, 2. The decays psi(3686) -> e(+)e(-)chi(cJ) and chi(cJ) -> e(+)e(-)J/psi are observed for the first time. The measured branching fractions are B(psi(3686) -> e(+)e(-)chi(cJ)) = (11.7 +/- 2.5 +/- 1.0) x 10(-4), (8.6 +/- 0.3 +/- 0.6) x 10(-4), (6.9 +/- 0.5 +/- 0.6) x 10(-4) for J = 0, 1, 2, and B(chi(cJ) -> e(+)e(-)J/psi) = (1.51 +/- 0.30 +/- 0.13)x10(-4), (3.73 +/- 0.09 +/- 0.25)x10(-3), (2.48 +/- 0.08 +/- 0.16)x10(-3) for J = 0, 1, 2, respectively. The ratios of the branching fractions B(psi(3686) -> e(+)e(-)chi(cJ))/B(psi(3686) -> gamma chi(cJ)) and B(chi(cJ) -> e(+)e(-)J/psi)/B(chi(cJ) -> gamma J/psi) are also reported. Also, the alpha values of helicity angular distributions of the e(+)e(-) pair are determined for psi(3686) -> e(+)e(-)chi(c1,2) and chi(c1,2) -> e(+)e(-)J/psi
Asymptotic Stability of a Plane CJ Detonation Wave
No full text. We study the asymptotic stability of a plane CJ detonation wave under the assumption of small resolved heat release (SRHR). We prove that the solution exists globally and that the solution converges uniformly to a shifted CJ detonation wave as t!+ 1 for initial data which are small perturbations of the CJ detonation wave. The weighted energy method is used to overcome the difficulty arising from the sonic property at the end of the reaction. The SRHR model allows us to treat the non-monotone spike in the profile of the CJ detonation wave by the characteristic energy estimate. Key words. CJ detonation, shock wave, traveling wave, sonic point, asymptotic behavior, weighted energy estimate, characteristic energy estimate. AMS(MOS) subject classifications. 35L65, 35B40, 35B50, 76L05, 76J10. Acknowledgments. The author is grateful to Prof. T.-P. Liu for pointing out the reference of Matsumura and Nishihara to her. This work was partially supported by ONR N00014-92-J-1890. 1 Introduc..
Observation of chi(cJ) -> 4K(S)(0)
No full textKolcu, Onur Buğra (Arel Author)By analyzing (448.1 +/- 2.9) x 10(6) psi(3686) events collected with the BESIII detector operating at the BEPCII collider, the decays of chi(c)(J) -> 4K(S)(0) (J = 0, 1, 2) are observed for the first time with statistical significances of 26.5 sigma, 5.9 sigma and 11.4 sigma, respectively. The product branching fractions of psi(3686) -> gamma chi(cJ), chi(cJ) -> 4K(S)(0 )are presented, and the branching fractions of chi(cJ) -> 4K(S)(0) decays are determined to be B-chi c0 -> 4KS0 = (5.76 +/- 0.34 +/- 0.38) x 10(-4), B-chi c1 -> 4KS0 = (0.35 +/- 0.09 +/- 0.03) x 10(-4) and B-chi c2 -> 4KS0( )= (1.14 +/- 0.15 +/- 0.08) x 10(-4), where the first uncertainties are statistical and the second are systematic, respectively
"These signs forerun the death or fall of kings": renegotiating masculinities and centrality in Shakespeare's second tetralogy through adaptation, direction and performance (PhD Thesis): [Appendix 1.4] Fall of Kings (2018) - Rehearsal and Production Photographs
No full textThis item contains appendices content relating to the PhD thesis, "These signs forerun the death or fall of kings": renegotiating masculinities and centrality in Shakespeare's second tetralogy through adaptation, direction and performance, by doctoral candidate CJ Turner-McMullan.Fall of Kings is an adaptation of William Shakespeare's Richard II, exploring performed and embodied representations of masculinities, and how performance may subvert binary dichotomies and gendered power onstage. The production was photographed during rehearsals at Bath Spa University and performances at Burdall's Yard, Bath in March 2018.Adapted and directed by CJ Turner-McMullanFight Direction // Russell Eccleston and Tiffany RhodesLighting Design // Annabel EllisSound Design and Composition // Edward TerryPerformers // Toby Underwood, Russell Eccleston, Gabrielle Finnegan, Ross Scott, James Leyshon, Adam Lloyd-James, Mike Harley, Kian Keanu PollardReproduced with permission from CJ Turner-McMullan and Sam Chandler (photographers).All media is copyright restricted. No unauthorised use or distribution without consent of the author. Use of this repository acknowledges cooperation with its policies and relevant copyright law.</p
chi(cJ) polarizations at the Fermilab Tevatron
No full textWe propose the measurement of chi (cJ) polarizations at high energy hadron colliders to study heavy quarkonium production mechanism. We find that the color-singlet model in the k(t) factorization approach predicts very different behavior for chi (cJ) polarizations at the Fermilab Tevatron compared with the NRQCD predictions in the collinear parton model. In the color-singlet k(t) factorization approach, for both chi (c1) and chi (c2) productions, the helicity h = 0 states dominate over other helicity states at large p(T). These properties are very useful in distinguishing between the two production mechanisms which are related to the interesting issue of J psi and psi' polarizations, and may provide a crucial test for the k(t) factorization approach. (C) 2001 Elsevier Science B.V. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000167082100012&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, MultidisciplinarySCI(E)3ARTICLE1-299-10450
QCD radiative corrections to chi(cJ) production at hadron colliders
No full textTo clarify the outstanding problem in charmonium production that existing theories cannot explain the observed cross sections of chi(cJ)(J = 0, 1, 2) and ratio R-chi c = sigma(chi c2)/sigma(chi c1) approximate to 0.75(in contrast to the spin counting value 5/3) at the Tevatron, we study the complete next-to-leading order radiative corrections in nonrelativistic QCD, and find next-to-leading order contributions of P-3(J)vertical bar 1 vertical bar are more important than leading order at high p(T), and P-3(1)vertical bar 1 vertical bar decreases slower than P-3(2)vertical bar 1 vertical bar, implying a natural explanation for the R-chi c puzzle. By fitting R-chi c, the predicted cross sections of chi(cJ) are found to agree with data. The result indicates coloroctet contribution is crucially needed, thus providing a unique test for heavy quarkonium production mechanisms. Feed-down contributions of chi(cJ) to prompt J/psi production are estimated to be substantial, about 30%-40% at p(T) = 20 GeV. Production of chi(cJ)(J = 0, 1, 2) at the LHC is also predicted.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000291464100001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)71ARTICLE11null8
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