Implications of surface noise for the motional coherence of trapped ions

Electric noise from metallic surfaces is a major obstacle towards quantum applications with trapped ions due to motional heating of the ions. Here, we discuss how the same noise source can also lead to pure dephasing of motional quantum states. The mechanism is particularly relevant at small ion-surface distances, thus imposing a new constraint on trap miniaturization. By means of a free induction decay experiment, we measure the dephasing time of the motion of a single ion trapped 50~$\mu$m above a Cu-Al surface. From the dephasing times we extract the integrated noise below the secular frequency of the ion. We find that none of the most commonly discussed surface noise models for ion traps describes both, the observed heating as well as the measured dephasing, satisfactorily. Thus, our measurements provide a benchmark for future models for the electric noise emitted by metallic surfaces.Comment: (5 pages, 4 figures

Asia's Land Down Under: the Socceroos and the 2015 Asian Cup

This is an Accepted Manuscript of an article published in Asia Pacific Journal of Sport and Social Science on 30 March 2015, available online: http://www.tandfonline.com/10.1080/21640599.2015.1021437On 31 January 2015, Australia's men's association football team (the Socceroos) won the Asian Cup for the first time, beating South Korea 2-1 after extra time in the final match played at Stadium Australia in Sydney. The victory in Sydney was a major milestone in two long-running processes – first, the ever closer relationship between Australia and Asia; second, the evolving status in Australian society of football, or ‘soccer’. In terms of assessing Australia's status as Asian, although part of the problem may lie with the Asian Football Confederation's definition of Asia, it is membership of that federation that has done more than any amount of trade relations and labour migration to give global public credence to the idea that Australia is possibly Asian, and almost certainly Asian-Pacific

Description of regional mitral annular nonplanarity in healthy human subjects: A novel methodology

ObjectiveFinite-element analysis demonstrates that the nonplanar shape of the mitral annulus diminishes mitral leaflet stress. It has therefore been postulated that repair with annuloplasty rings that maintain the nonplanar shape of the annulus could increase repair durability. Although the global nonplanarity of the mitral annulus has been adequately characterized, design of such a ring requires a quantitative description of regional annular geometry. By using real-time 3-dimensional echocardiography in conjunction with available image processing software, we developed a methodology for describing regional annular geometry and applied it to the characterization of the normal human mitral annulus.MethodsFive healthy volunteers underwent mitral valve imaging with real-time 3-dimensional echocardiography. Regional annular height was calculated at 36 evenly spaced intervals.ResultsMaximal annular height/commissural width ratio was found to occur at the midpoint of the anterior annulus in all cases. These values averaged 26% ± 3.1%, whereas those for the midposterior annulus averaged 18% ± 3.0%. The average commissural width was 35.2 ± 6.0 mm. Although substantial spatial heterogeneity was observed, regional annular height at a given rotational position was highly conserved among subjects when normalized to commissural width.ConclusionsThese quantitative imaging and analytic techniques demonstrate that the normal human mitral annulus is regionally heterogeneous in its nonplanarity, and they establish a means of describing annular geometry at a regional level. With wider application, these techniques may be used both to characterize pathologic annular geometry and to optimize the design of mitral valve annuloplasty devices

The diversity of bioactive proteins in Australian snake venoms

Australian elapid snakes are among the most venomous in the world. Their venoms contain multiple components that target blood hemostasis, neuromuscular signaling, and the cardiovascular system. We describe here a comprehensive approach to separation and identification of the venom proteins from 18 of these snake species, representing nine genera. The venom protein components were separated by two-dimensional PAGE and identified using mass spectrometry and de novo peptide sequencing. The venoms are complex mixtures showing up to 200 protein spots varying in size from 10. These include many proteins identified previously in Australian snake venoms, homologs identified in other snake species, and some novel proteins. In many cases multiple trains of spots were typically observed in the higher molecular mass range (> 20 kDa) (indicative of post-translational modification). Venom proteins and their post-translational modifications were characterized using specific kantibodies, phosphoprotein- and glycoprotein-specific stains, enzymatic digestion, lectin binding, and antivenom reactivity. In the lower molecular weight range, several proteins were identified, but the predominant species were phospholipase A(2) and alpha-neurotoxins, both represented by different sequence variants. The higher molecular weight range contained proteases, nucleotidases, oxidases, and homologs of mammalian coagulation factors. This information together with the identification of several novel proteins (metalloproteinases, vespryns, phospholipase A(2) inhibitors, protein-disulfide isomerase, 5'-nucleotidases, cysteinerich secreted proteins, C-type lectins, and acetylcholinesterases) aids in understanding the lethal mechanisms of elapid snake venoms and represents a valuable resource for future development of novel human therapeutics

The Performance of Private Equity Funds: Does Diversification Matter?

This paper is the first systematic analysis of the impact of diversification on the performance of private equity funds. A unique data set allows the exact evaluation of diversification across the dimensions financing stages, industries, and countries. Very different levels of diversification can be observed across sample funds. While some funds are highly specialized others are highly diversified. The empirical results show that the rate of return of private equity funds declines with diversification across financing stages, but increases with diversification across industries. Accordingly, the fraction of portfolio companies which have a negative return or return nothing at all, increase with diversification across financing stages. Diversification across countries has no systematic effect on the performance of private equity funds

Combined RAF1 protein expression and p53 mutational status provides a strong predictor of cellular radiosensitivity

The tumour suppressor gene, p53, and genes coding for positive signal transduction factors can influence transit through cell-cycle checkpoints and modulate radiosensitivity. Here we examine the effects of RAF1 protein on the rate of exit from a G2/M block induced by γ-irradiation in relation to intrinsic cellular radiosensitivity in human cell lines expressing wild-type p53 (wtp53) protein as compared to mutant p53 (mutp53) protein. Cell lines which expressed mutp53 protein were all relatively radioresistant and exhibited no relationship between RAF1 protein and cellular radiosensitivity. Cell lines expressing wtp53 protein, however, showed a strong relationship between RAF1 protein levels and the radiosensitivity parameter SF2. In addition, when post-irradiation perturbation of G2/M transit was compared using the parameter T50 (time after the peak of G2/M delay at which 50% of the cells had exited from a block induced by 2 Gy of irradiation), RAF1 was related to T50 in wtp53, but not mutp53, cell lines. Cell lines which expressed wtp53 protein and high levels of RAF1 had shorter T50s and were also more radiosensitive. These results suggest a cooperative role for wtp53 and RAF1 protein in determining cellular radiosensitivity in human cells, which involves control of the G2/M checkpoint. © 2000 Cancer Research Campaig

Low Cost and Compact Quantum Cryptography

We present the design of a novel free-space quantum cryptography system, complete with purpose-built software, that can operate in daylight conditions. The transmitter and receiver modules are built using inexpensive off-the-shelf components. Both modules are compact allowing the generation of renewed shared secrets on demand over a short range of a few metres. An analysis of the software is shown as well as results of error rates and therefore shared secret yields at varying background light levels. As the system is designed to eventually work in short-range consumer applications, we also present a use scenario where the consumer can regularly 'top up' a store of secrets for use in a variety of one-time-pad and authentication protocols.Comment: 18 pages, 9 figures, to be published in New Journal of Physic