Implementation of Cavity Squeezing of a Collective Atomic Spin

We squeeze unconditionally the collective spin of a dilute ensemble of laser-cooled rubidium-87 atoms using their interaction with a driven optical resonator. The shape and size of the resulting spin uncertainty region are well described by a simple analytical model [M.H.S., I.D.L., V.V., arXiv:0911.3936] through two orders of magnitude in the effective interaction strength, without free parameters. We deterministically generate states with up to 5.6(6) dB of metrologically relevant spin squeezing on the canonical rubidium-87 hyperfine clock transition.Comment: 4 pages, 2 figures. To be published in Phys. Rev. Lett. Some additional details and clarified wording in response to referee comments. Figures and results unchange

Squeezing the Collective Spin of a Dilute Atomic Ensemble by Cavity Feedback

We propose and analyze a simple method to squeeze dynamically and unconditionally the collective spin of a dilute atomic ensemble by interaction with a driven mode of an optical resonator, as recently demonstrated [I. D. L., M. H. S., and V. V., Phys. Rev. Lett. 104, 073602 (2010)]. We show that substantial squeezing can be achieved in the regime of strong collective ensemble-resonator coupling. The squeezing is ultimately limited either by photon emission into free space or by the curvature of the Bloch sphere. We derive both limits and show where each prevails.Comment: 4 pages, 2 figures. Minor revision. To appear in Phys. Rev.

The experiences of first time fathers in Western Australia: A qualitative analysis into the transition to fatherhood

According to critical life events framework, the transition to parenthood can be filled with anticipation and excitement, yet it can be extremely difficult for some. The transition to parenthood begins during pregnancy when the parents begin to form emotional bonds with the unborn child, and continues for some time after the birth of the baby, ending when the infant reaches two years of age. There exists a vast amount of research on the experiences of the female transition, but there is little in comparison about the experiences of the male transition to becoming a father for the first time. The aim of this research was to investigate the experiences of first time fathers in Perth, Western Australia, in the 21st century. Using thematic content analysis, interviews with five first time fathers aged between 25 and 38 (M = 31, SD = 6.12), with infants aged between 2 and 20 months (M = 8.8, SD = 8.23) were conducted. Whilst there is a deficiency in current empirical evidence on the transitional experience of first time fathers in Western Australia, the data revealed aspects of fatherhood that are traditionally ignored. This revelation is two-fold in benefit, in that it acknowledges and adds meaning to the male perspective in child rearing, and adds to the body of literature outside other countries such as the United States of America. This research may aid health care professionals gain a better understanding of the issues faced by first time fathers, and identifies the need for improvement in current education and information packages assisting first time fathers with their transition to fatherhood

A comparison of surface sensible and latent heat fluxes from aircraft and surface measurements in FIFE 1987

Surface fluxes of sensible and latent heat over a tall-grass prairie in central Kansas, as measured by 22 surface stations during FIFE 1987, are compared with values gained indirectly by linear extrapolation of aircraft-measured flux profiles to the surface. The results of 33 such comparisons covering the period 26 June to 13 October 1987 indicate that the sensible heat flux profiles were generally more linear with less scatter in the measurements at each level than were the latent heat flux profiles, the profile extrapolations of sensible heat flux in general underestimate the surface averages by about 30 percent, with slightly better agreement during periods of small flux, and the profile extrapolations of latent heat flux in general underestimate the surface averages by about 15 percent, with overestimates during periods of small fluxes (dry conditions) and overestimates during periods of large fluxes (moist conditions). Possible origins of the differences between the two sets of measurements are discussed, as directions for further research

The surface filtration of oil in water dispersions with imposed fluid rotation

The separation of oil in water dispersions is an important process, with research principally concentrating upon polymeric and ceramic filters where the filtration mechanism is predominantly by capture within the depth of the filter. This work utilises novel metal filters which possess a non-tortuous pore channel and so filter by a sieving mechanism. An evaluation of a variety of types of metal surface filters was conducted with a large proportion of the research focusing upon a filter possessing circular pores which open into a conical shape. Rejection of challenging emulsified oil droplets was solely by exclusion due to size at this pore. Enhancement of emulsion filtration was combined with the surface filters using a selection of rod and helical inserts within a tubular filter to modify the flow conditions; in the case of helical inserts to produce a centrifugal velocity upon the less dense oil droplets away from the filter surface. Further filtration enhancement was produced by air backflushing to alleviate fouling of the filter surface and electrolytic generation of bubbles to capture oil drops on bubbles. The latter method increased the overall feed size and should have increased the centrifugal separation by lowering particle or aggregate density. Research is also reported into the mechanism of rejection of emulsified oil droplets using filters with circular pores. The mechanism has been evaluated and shown to depend on the capillary pressure of deformable oil drops impinging upon the pore. A mathematical model is described, which predicts the deformation of drops using the physical properties of contact angle and interfacial tension combined with the properties of pore size, shape and droplet size

Testing use of mitochondrial COI sequences for the identification and phylogenetic analysis of New Zealand caddisflies (Trichoptera)

We tested the hypothesis that cytochrome c oxidase subunit 1 (COI) sequences would successfully discriminate recognised species of New Zealand caddisflies. We further examined whether phylogenetic analyses, based on the COI locus, could recover currently recognised superfamilies and suborders. COI sequences were obtained from 105 individuals representing 61 species and all 16 families of Trichoptera known from New Zealand. No sequence sharing was observed between members of different species, and congeneric species showed from 2.3 to 19.5% divergence. Sequence divergence among members of a species was typically low (mean = 0.7%; range 0.0–8.5%), but two species showed intraspecific divergences in excess of 2%. Phylogenetic reconstructions based on COI were largely congruent with previous conclusions based on morphology, although the sequence data did not support placement of the purse-cased caddisflies (Hydroptilidae) within the uncased caddisflies, and, in particular, the Rhyacophiloidea. We conclude that sequence variation in the COI gene locus is an effective tool for the identification of New Zealand caddisfly species, and can provide preliminary phylogenetic inferences. Further research is needed to ascertain the significance of the few instances of high intra-specific divergence and to determine if any instances of sequence sharing will be detected with larger sample sizes