An intelligent, free-flying robot

The ground based demonstration of the extensive extravehicular activity (EVA) Retriever, a voice-supervised, intelligent, free flying robot, is designed to evaluate the capability to retrieve objects (astronauts, equipment, and tools) which have accidentally separated from the Space Station. The major objective of the EVA Retriever Project is to design, develop, and evaluate an integrated robotic hardware and on-board software system which autonomously: (1) performs system activation and check-out; (2) searches for and acquires the target; (3) plans and executes a rendezvous while continuously tracking the target; (4) avoids stationary and moving obstacles; (5) reaches for and grapples the target; (6) returns to transfer the object; and (7) returns to base

Big Gay Church: Religion, Religiosity, and Visual Culture

Five academics explore their performed occupations of the National Art Education Association Annual Meetings. They have annually mounted Big Gay Church (BGC) services that deconstruct and question the ways visual culture, media representations, scriptural interpretations, and religious teaching have constructed (at times harmful) depictions of lesbian, gay, bisexual, transgender, queer and questioning (LGBTQ2) subjects. This essay recounts how co-authors have drawn on their multiple experiences with/in churches to play with religious rituals and narratives in ways that queerly comment on the damage or support organized religions offer LGBTQ2 students and educators

Tests of Transfer Reaction Determinations of Astrophysical S-Factors

The ${}^{16}O ({}^{3}He,d) {}^{17}F$ reaction has been used to determine asymptotic normalization coefficients for transitions to the ground and first excited states of ${}^{17}F$. The coefficients provide the normalization for the tails of the overlap functions for ${}^{17}F \to{}^{16}O + p$ and allow us to calculate the S-factors for ${}^{16}O (p,\gamma){}^{17}F$ at astrophysical energies. The calculated S-factors are compared to measurements and found to be in very good agreement. This provides the first test of this indirect method to determine astrophysical direct capture rates using transfer reactions. In addition, our results yield S(0) for capture to the ground and first excited states in $^{17}F$, without the uncertainty associated with extrapolation from higher energies.Comment: 6 pages, 2 figure

Multiple electromagnetic electron positron pair production in relativistic heavy ion collisions

We calculate the cross sections for the production of one and more electron-positron pairs due to the strong electromagnetic fields in relativistic heavy ion collisions. Using the generating functional of fermions in an external field we derive the N-pair amplitude. Neglecting the antisymmetrisation in the final state we find that the total probability to produce N pairs is a Poisson distribution. We calculate total cross sections for the production of one pair in lowest order and also include higher-order corrections from the Poisson distribution up to third order. Furthermore we calculate cross sections for the production of up to five pairs including corrections from the Poisson distribution.Comment: 13 pages REVTeX, 4 Postscript figures, This and related papers may also be obtained from http://www.phys.washington.edu/~hencken

Weighing Super-Massive Black Holes with Narrow Fe Kα\alpha Line

It has been suggested that the narrow cores of the Fe K$\alpha$ emission lines in Active Galactic Nuclei (AGNs) are likely produced in the torus, the inner radius of which can be measured by observing the lag time between the $V$ and $K$ band flux variations. In this paper we compare the virial products of the infrared time lags and the narrow Fe K$\alpha$ widths for 10 type 1 AGNs with the black hole masses from other techniques. We find the narrow Fe K$\alpha$ line width is in average 2.6$^{+0.9}_{-0.4}$ times broader than expected assuming an isotropic velocity distribution of the torus at the distance measured by the infrared lags. We propose the thick disk model of the torus could explain the observed larger line width. Another possibility is the contamination by emission from the broad line region or the outer accretion disk. Alternatively, the narrow iron line might originate from the inner most part of the obscuring torus within the sublimation radius, while the infrared emission from outer cooler part. We note the correlation between the black hole masses based on this new technique and those based on other known techniques is statistically insignificant. We argue that this could be attributed to the small sample size and the very large uncertainties in the measurements of iron K line widths. The next generation of X-ray observatories could help verify the origin of the narrow iron K$\alpha$ line and the reliability of this new technique.Comment: 12 pages, 2 figures, 2 tables, Science China G, in pres

Expanding the parameters of academia

This paper draws on qualitative data gathered from two studies funded by the UK Leadership Foundation for Higher Education to examine the expansion of academic identities in higher education. It builds on Whitchurch’s earlier work, which focused primarily on professional staff, to suggest that the emergence of broadly based projects such as widening participation, learning support and community partnership is also impacting on academic identities. Thus, academic as well as professional staff are increasingly likely to work in multi-professional teams across a variety of constituencies, as well as with external partners, and the binary distinction between ‘academic’ and ‘non-academic’ roles and activities is no longer clear-cut. Moreover, there is evidence from the studies of an intentionality about deviations from mainstream academic career routes among respondents who could have gone either way. Consideration is therefore given to factors that influence individuals to work in more project-oriented areas, as well as to variables that affect ways in which these roles and identities develop. Finally, three models of academically oriented project activity are identified, and the implications of an expansion of academic identities are reviewed

How does breakup influence the total fusion of 6,7^{6,7}Li at the Coulomb barrier?

Total (complete + incomplete) fusion excitation functions of $^{6,7}$Li on $^{59}$Co and $^{209}$Bi targets around the Coulomb barrier are obtained using a new continuum discretized coupled channel (CDCC) method of calculating fusion. The relative importance of breakup and bound-state structure effects on total fusion is particularly investigated. The effect of breakup on fusion can be observed in the total fusion excitation function. The breakup enhances the total fusion at energies just around the barrier, whereas it hardly affects the total fusion at energies well above the barrier. The difference between the experimental total fusion cross sections for $^{6,7}$Li on $^{59}$Co is notably caused by breakup, but this is not the case for the $^{209}$Bi target.Comment: 9 pages, 9 figures, Submitted to Phys. Rev.

Exact Z2Z^2 scaling of pair production in the high-energy limit of heavy-ion collisions

The two-center Dirac equation for an electron in the external electromagnetic field of two colliding heavy ions in the limit in which the ions are moving at the speed of light is exactly solved and nonperturbative amplitudes for free electron-positron pair production are obtained. We find the condition for the applicability of this solution for large but finite collision energy, and use it to explain recent experimental results. The observed scaling of positron yields as the square of the projectile and target charges is a result of an exact cancellation of a nonperturbative charge dependence and holds as well for large coupling. Other observables would be sensitive to nonperturbative phases.Comment: 4 pages, Revtex, no figures, submitted to PR

Higher Order Processes in Electromagnetic Production of Electron Positron Pairs in Relativistic Heavy Ion Collisions

We study higher-order effects in the electromagnetic production of electron-positron pairs in relativistic heavy ion collisions. Treating the field of the heavy ions as an external field and neglecting the interaction among electrons and positrons, we show that the $N$-pair creation amplitude is the antisymmetrised product of $N$ one-pair creation amplitudes and the vacuum amplitude. Neglecting contributions coming from exchange terms, we show that the total probability for $N$ pairs is approximately a Poisson distribution. We investigate further the structure of the reduced one-pair amplitude, concentrating especially on multiple-particle corrections. We calculate the first of these corrections in second order Magnus theory based on our previous result in second-order Born approximation for impact parameter $b$ zero. Explicit calculations show that the total probability is increased up to 10 \% by this correction for realistic collider parameters. The calculations can also be used to confirm the use of the Poisson distribution for the total probability.Comment: 29 pages RevTeX and 12 uuencoded figures (compressed postscript