Excitation and characterization of long-lived hydrogenic Rydberg states of nitric oxide

High Rydberg states of nitric oxide (NO) with principal quantum numbers between 40 and 100 and lifetimes in excess of 10 $\mu$s have been prepared by resonance enhanced two-color two-photon laser excitation from the X $^2\Pi_{1/2}$ ground state through the A $^2\Sigma^+$ intermediate state. Molecules in these long-lived Rydberg states were detected and characterized 126 $\mu$s after laser photoexcitation by state-selective pulsed electric field ionization. The laser excitation and electric field ionization data were combined to construct two-dimensional spectral maps. These maps were used to identify the rotational states of the NO$^+$ ion core to which the observed series of long-lived hydrogenic Rydberg states converge. The results presented pave the way for Rydberg-Stark deceleration and electrostatic trapping experiments with NO, which are expected to shed further light on the decay dynamics of these long-lived excited states, and are of interest for studies of ion-molecule reactions at low temperatures.Comment: 12 pages, 10 figure

Positronium emission from mesoporous silica studied by laser-enhanced time-of-flight spectroscopy

The use of mesoporous silica films for the production and study of positronium (Ps) atoms has become increasingly important in recent years, providing a robust source of free Ps in vacuum that may be used for a wide variety of experiments, including precision spectroscopy and the production of antihydrogen. The ability of mesoporous materials to cool and confine Ps has also been utilized to conduct measurements of Ps–Ps scattering and Ps2 molecule formation, and this approach offers the possibility of making a sufficiently dense and cold Ps ensemble to realize a Ps Bose–Einstein condensate. As a result there is great interest in studying the dynamics of Ps atoms inside such mesoporous structures, and how their morphology affects Ps cooling, diffusion and emission into vacuum. It is now well established that Ps atoms are initially created in the bulk of such materials and are subsequently ejected into the internal voids with energies of the order of 1 eV, whereupon they rapidly cool via hundreds of thousands of wall collisions. This process can lead to thermalisation to the ambient sample temperature, but will be arrested when the Ps deBroglie wavelength approaches the size of the confining mesopores. At this point diffusion through the pore network can only proceed via tunneling, at a much slower rate. An important question then becomes, how long does it take for the Ps atoms to cool and escape into vacuum? In a direct measurement of this process, conducted using laser-enhanced positronium time-of-flight spectroscopy, we show that cooling to the quantum confinement regime in a film with approximately 5 nm diameter pores is nearly complete within 5 ns, and that emission into vacuum takes ~10 ns when the incident positron beam energy is 5 keV. The observed dependence of the Ps emission time on the positron implantation energy supports the idea that quantum confined Ps does not sample all of the available pore volume, but rather is limited to a subset of the mesoporous network

Measuring the Local Economic Impact of Cooperatives

The ability to measure the economic importance of cooperatives to communities is not purely an academic question. Policy makers, cooperative organizations, and community development practitioners are increasingly asking for such information. The most commonly used methodology is input-output analysis. The limitations of input-output analysis when applied to cooperatives have not yet been comprehensively explained in the literature, although they significantly affect the application of the model as well as the interpretation of results. We discuss five issues that need to be addressed when using input-output models and suggest additional analysis that should be completed to gain an accurate assessment of the local economic impact of cooperatives.cooperatives, economic impact, community development, input-output models, Agribusiness,

Examining the Examiner: Waiver of the Attorney-Client Privilege and the Outer Limits of an Examiner\u27s Powers in Bankruptcy

This article discusses the traditional role of an examiner in bankruptcy proceedings, as well as the fact that the role of an examiner is often expanded in complex Chapter 11 cases to include duties and powers normally reposed in bankruptcy trustees. The article examines the interesting question of whether an examiner may be cloaked with the powers of a bankruptcy trustee, and discusses this question in the context of addressing the issue of whether an examiner in bankruptcy has the power to waive a debtor\u27s attorney-client privilege

Precision VLBI astrometry: Instrumentation, algorithms and pulsar parallax determination

(Abridged) This thesis describes the development of DiFX, the first general-purpose software correlator for radio interferometry, and its use with the Australian Long Baseline Array (LBA) to complete the largest VLBI pulsar astrometry program undertaken to date in the Southern Hemisphere. This two year astrometry program has resulted in the measurement of seven new pulsar parallaxes, more than trebling the number of measured VLBI pulsar parallaxes in the Southern Hemisphere. The measurements included a determination of the distance and transverse velocity of PSR J0437-4715 with better than 1% accuracy, enabling improved tests of General Relativity, and the first significant measurement of parallax for the famous double pulsar system PSR J0737-3039A/B, which will allow tests of General Relativity in this system to proceed to the 0.01% level. The DiFX software correlator developed to enable this science has been extensively tested and is now an integral part of the upgraded LBA Major National Research Facility; furthermore, it has been selected to facilitate a substantial sensitivity upgrade for the US Very Long Baseline Array.Comment: PhD Thesis, Swinburne University, accepted January 2009. 202 pages, 51 figures. For a version with high resolution images, see http://www.aoc.nrao.edu/~adeller/AdamDellerPhDThesis.pd

A novel search for gravitationally lensed radio sources in wide-field VLBI imaging from the mJIVE-20 survey

We present a novel pilot search for gravitational lenses in the mJIVE-20 survey, which observed $24\,903$ radio sources selected from FIRST with the VLBA at an angular resolution of 5 mas. We have taken the visibility data for an initial $3\,640$ sources that were detected by the mJIVE-20 observations and re-mapped them to make wide-field images, selecting fourteen sources that had multiple components separated by $\geq100$ mas, with a flux-ratio of $\leq15$:$1$ and a surface brightness consistent with gravitational lensing. Two of these candidates are re-discoveries of gravitational lenses found as part of CLASS. The remaining twelve candidates were then re-observed at 1.4 GHz and then simultaneously at 4.1 and 7.1 GHz with the VLBA to measure the spectral index and surface brightness of the individual components as a function of frequency. Ten were rejected as core-jet or core-hotspot(s) systems, with surface brightness distributions and/or spectral indices inconsistent with gravitational lensing, and one was rejected after lens modelling demonstrated that the candidate lensed images failed the parity test. The final lens candidate has an image configuration that is consistent with a simple lens mass model, although further observations are required to confirm the lensing nature. Given the two confirmed gravitational lenses in the mJIVE-20 sample, we find a robust lensing-rate of $1$:($318\pm225$) for a statistical sample of 635 radio sources detected on mas-scales, which is consistent with that found for CLASS.Comment: 31 pages, 22 figures; accepted for publication in MNRA

Faith in view: religion and pirituality in factual British television 2000-2009

This thesis explores the nature of, and developments in, the coverage of religion and spirituality in factual British television programming 2000-2009, focusing on mainstream terrestrial networks (BBC, ITV, Channel 4, Five) with a public service remit. The study employs a mixed-method approach with an emphasis on discourse. Working within a broadly Critical Discourse Analysis (CDA) framework, it explores discourses around religion/spirituality, identity and nationality across a range of environments – from the programmes themselves to audience discussion (in focus groups, questionnaires, forum and Twitter discussions, YouTube comments and blogs) and industry accounts of production (in policies, guidelines, publicity and interviews with several of those involved at different stages of the production process). The theoretical context of this study includes debates over the ‘secularisation thesis’, the rise of ‘fundamentalism’, the individualisation of religion and the apparent interest in ‘spirituality’ as opposed to ‘religion’, the role of public service broadcasting, issues of media representation of minorities, and developments within British factual television genres. The study concludes that, despite public service commitments, there is a lack of diversity in the portrayal of religion and spirituality within mainstream factual British television, with Christianity, Islam and Atheism dominating coverage. All faiths are represented by a limited repertoire of signifiers. Audiences, both those who have been researched for this study and those who feature in research by the broadcasters and Ofcom, often complain about what they perceive as 'misrepresentation', whilst at the same time discussing 'other' people in stereotypical terms. Within all of the discursive contexts studied, there is a construction of Britain as a liberal, tolerant, moderate place, where spiritual/religious belief is acceptable as long as it operates within particular parameters. When beliefs and practices do not conform to these standards, they are exoticised, ridiculed or presented as dangerous, and often linked to other nations, thus emphasising how they are not a British way of expressing one's spirituality. However, I argue that the problematic nature of these constructions is in part a result of the complex interaction between audiences, programme makers, policy, academic discourse and media texts. Each area of discourse informs the other, replicating and reinforcing notions of Britishness, religion and spirituality across multiple contexts

Selective Production of Rydberg-Stark States of Positronium

Rydberg positronium (Ps) atoms have been prepared in selected Stark states via two-step (1s→2p→nd/ns) optical excitation. Two methods have been used to achieve Stark-state selection: a field ionization filter that transmits the outermost states with positive Stark shifts, and state-selected photoexcitation in a strong electric field. The former is demonstrated for n=17 and 18 while the latter is performed for n=11 in a homogeneous electric field of 1.9  kV/cm. The observed spectral intensities and their dependence on the polarization of the laser radiation are in agreement with calculations that include the perturbations of the intermediate n=2 manifold. Our results pave the way for the generation of Rydberg Ps atoms with large electric dipole moments that are required for the realization of schemes to control their motion using inhomogeneous electric fields, an essential feature of some proposed Ps free-fall measurements requiring focused beams of long-lived atoms

'Academics cry censorship, students cry trauma': Media representations of ‘safer spaces’ debates in Higher Education

Conference presentatio