Shape-preserving and unidirectional frequency conversion using four-wave mixing Bragg scattering

In this work, we investigate the properties of four-wave mixing Bragg scattering in a configuration that employs orthogonally polarized pumps in a birefringent waveguide. This configuration enables a large signal conversion bandwidth, and allows strongly unidirectional frequency conversion as undesired Bragg-scattering processes are suppressed by waveguide birefringence. Moreover, we show that this form of four-wave mixing Bragg scattering preserves the (arbitrary) signal pulse shape, even when driven by pulsed pumps.Comment: 11 pages + refs, 5 figure

d1005+68: A New Faint Dwarf Galaxy in the M81 Group

We present the discovery of d1005+68, a new faint dwarf galaxy in the M81 Group, using observations taken with the Subaru Hyper Suprime-Cam. d1005+68's color-magnitude diagram is consistent with a distance of $3.98_{-0.43}^{+0.39}$ Mpc, establishing group membership. We derive an absolute $V$-band magnitude, from stellar isochrone fitting, of $M_{V} = -7.94_{-0.50}^{+0.38}$, with a half-light radius of $r_{h} = 188_{-41}^{+39}$ pc. These place d1005+68 within the radius-luminosity locus of Local Group and M81 satellites and among the faintest confirmed satellites outside the Local Group. Assuming an age of 12 Gyr, d1005+68's red giant branch is best fit by an isochrone of [Fe/H] $= -1.90 \pm 0.24$. It has a projected separation from nearby M81 satellite BK5N of only 5 kpc. As this is well within BK5N's virial radius, we speculate that d1005+68 may be a satellite of BK5N. If confirmed, this would make d1005+68 one of the first detected satellites-of-a-satellite.Comment: 7 pages, 4 figures, 1 table, additional affiliations include

Association of key foods and beverages with obesity in Australian schoolchildren

Objective: To examine the pattern of intake of key foods and beverages of children aged 4&ndash;12 years and the association with weight status.Design and setting: A computer-assisted telephone interview was used to determine the intake of fruit, vegetables, packaged snacks, fast foods and sweetened drinks &lsquo;yesterday&rsquo; and &lsquo;usually&rsquo; as reported by parents/guardians of a representative sample of 2184 children from the Barwon South-Western region of Victoria, Australia.Results: Children who consumed .2&ndash;3, .3&ndash;4 and .4 servings of fruit juice/drinks &lsquo;yesterday&rsquo; were, respectively, 1.7 (95% confidence interval (CI) 1.2&ndash;2.2), 1.7 (95% CI 1.2&ndash;2.5) and 2.1 (95% CI 1.5&ndash;2.9) times more likely to be overweight/obese compared with those who had no servings of fruit juice/drink &lsquo;yesterday&rsquo;, adjusted for age, gender and socio-economic status (SES). Further, children who had $3 servingsof soft drink &lsquo;yesterday&rsquo; were 2.2 (95% CI 1.3&ndash;3.9) times more likely to beoverweight/obese compared with those who had no servings of soft drink &lsquo;yesterday&rsquo;, adjusted for age, gender and SES. In addition, children who &lsquo;usually&rsquo; drank fruit juice/drinks twice or more per day were 1.7 (95% CI 1.2&ndash;2.4) times more likely to be overweight/obese compared with those who drank these beverages once or less per week, adjusted for age, gender and SES. Although fast foods and packaged snacks were regularly eaten, there were no associations between weight status andconsumption of these foods.Conclusions: Intake of sweetened beverages was associated with overweight and obesity in this population of Australian schoolchildren and should be a target for intervention programmes aimed at preventing unhealthy weight gain in children.<br /

Tropical Forests Of Oceania. Anthropological Perspectives

The tropical forests of Oceania are an enduring source of concern for indigenous communities, for the migrants who move to them, for the states that encompass them within their borders, for the multilateral institutions and aid agencies, and for the non-governmental organisations that focus on their conservation. Grounded in the perspective of political ecology, contributors to this volume approach forests as socially alive spaces produced by a confluence of local histories and global circulations. In doing so, they collectively explore the multiple ways in which these forests come into view and therefore into being. Exploring the local dynamics within and around these forests provides an insight into regional issues that have global resonance. Intertwined as they are with cosmological beliefs and livelihoods, as sites of biodiversity and Western desire, these forests have been and are still being transformed by the interaction of foreign and local entities. Focusing on case studies from Papua New Guinea, the Solomon Islands and the Gambier Islands, this volume brings new perspectives on how Pacific Islanders continue to creatively engage with the various processes at play in and around their forests

A Dirac sea pilot-wave model for quantum field theory

We present a pilot-wave model for quantum field theory in which the Dirac sea is taken seriously. The model ascribes particle trajectories to all the fermions, including the fermions filling the Dirac sea. The model is deterministic and applies to the regime in which fermion number is superselected. This work is a further elaboration of work by Colin, in which a Dirac sea pilot-wave model is presented for quantum electrodynamics. We extend his work to non-electromagnetic interactions, we discuss a cut-off regularization of the pilot-wave model and study how it reproduces the standard quantum predictions. The Dirac sea pilot-wave model can be seen as a possible continuum generalization of a lattice model by Bell. It can also be seen as a development and generalization of the ideas by Bohm, Hiley and Kaloyerou, who also suggested the use of the Dirac sea for the development of a pilot-wave model for quantum electrodynamics.Comment: 41 pages, no figures, LaTex, v2 minor improvements and addition