136 research outputs found

    The Blue Emu

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    The primary goal in designing the Blue Emu was to provide an airline with a cost efficient and profitable means of transporting passengers between the major cities in Aeroworld. The design attacks the market where a demand for inexpensive transportation exists and for this reason the Blue Emu is an attractive investment for any airline. In order to provide a profitable aircraft, special attention was paid to cost and economics. For example, in manufacturing, simplicity was stressed in structural design to reduce construction time and cost. Aerodynamic design employed a tapered wing which reduced the induced drag coefficient while also reducing the weight of the wing. Even the propulsion system was selected with cost effectiveness in mind, yet also to maintain the marketability of the aircraft. Thus, in every aspect of the design, consideration was given to economics and marketability of the final product

    Creating Improved Communication Between Nursing and Physicians: Importance of Collaboration within a Hospital System

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    Background: Optimal communication between all members of the healthcare team is important to ensure safe and efficient patient care.Objective: To improve communication between nurses and resident physicians by developing and implementing a paging protocol.Methods: A resident-led workgroup was assembled to identify opportunities for improving communication. A survey was designed to assess current practices and perceptions related to resident and nurse communication. A facilitated focus group of residents and nurses met on two separate occasions to review the survey results and develop a set of mutually agreeable paging guidelines. The group chose to adopt the ISBARR communication tool and planned educational interventions accordingly. Residents and nurses were resurveyed roughly three months’ post-intervention.Results: The results indicated a 12.8% reduction (p=0.017) in the percentage of nurse respondents that “never” inquire whether or not another nurse on the unit needs to speak with the same physician prior to paging. A 10.3% increase (p=0.033) in resident respondents that “usually” receive grouped pages, and an 11% reduction (p=0.042) in the percentage of resident respondents that “never: receive grouped pages. However, only 53.3% (n=60) of nurse respondents and 44.1% (n=68) of resident respondents felt their ISBARR training was adequate. Moreover, only 38.4% and 30.9% of nurse and resident respondents, respectively felt the paging guidelines and ISBARR had improved overall communications between the two groups.Conclusions: While the follow-up survey results revealed some improvements in paging practices, the need for continued education was clear

    Ground deformation analysis at Campi Flegrei (Southern Italy) by CGPS and tide-gauge network

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    Campi Flegrei caldera is located 15 km west of the city of Naples, within the central-southern sector of a large graben called Campanian Plain. It is an active volcanic area marked by a quasi-circular caldera depression, formed by a huge ignimbritic eruption occurred about 37000 years ago. This caldera was generated by several collapses produced by strong explosive eruptions (the last eruption, occurred in 1538, built an about 130 m spatter cone called Mt. Nuovo). Campi Flegrei area periodically experiences significant deformation episodes, with uplift phenomena up to more than 3.5 m in 15 years (from 1970 to 1984), which caused during 1983-84 the temporary evacuation of about 40000 people from the ancient part of Pozzuoli town. The deformation field obtainable by CGPS and tidegauge stations plays an important role for the modelling and interpretation of volcanic phenomena, as well as for forecasting purposes. The structural complexity of the Campi Flegrei area, together with the evidence of a strong interaction between magmatic chamber and shallow geothermal system, calls for a detailed characterization of the substructure and of magma-water interaction processes. The incoming experiment of deep drilling, down to about 4 km, will give detailed structural and physical constraints able to resolve the intrinsic ambiguities of geophysical data and in particular geodetic ones. In this poster we describe the recent ground deformations at Campi Flegrei area by means of GPS technique and tide gauge stations, discussing the possible interpretations also in light of further constraints likely coming from the next CFDDP (Campi Flegrei Deep Drilling) deep drilling experiment

    Establishment Failure in Biological Invasions: A Case History of Littorina littorea in California, USA

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    The early stages of biological invasions are rarely observed, but can provide significant insight into the invasion process as well as the influence vectors have on invasion success or failure.We characterized three newly discovered populations of an introduced gastropod, Littorina littorea (Linné, 1758), in California, USA, comparing them to potential source populations in native Europe and the North American East Coast, where the snail is also introduced. Demographic surveys were used to assess spatial distribution and sizes of the snail in San Francisco and Anaheim Bays, California. Mitochondrial DNA was sequenced and compared among these nascent populations, and various populations from the North American East Coast and Europe, to characterize the California populations and ascertain their likely source. Demographic and genetic data were considered together to deduce likely vectors for the California populations. We found that the three large California L. littorea populations contained only adult snails and had unexpectedly high genetic diversity rather than showing an extreme bottleneck as typically expected in recent introductions. Haplotype diversity in Californian populations was significantly reduced compared to European populations, but not compared to East Coast populations. Genetic analyses clearly suggested the East Coast as the source region for the California introductions.The California L. littorea populations were at an early, non-established phase of invasion with no evidence of recruitment. The live seafood trade is the most likely invasion vector for these populations, as it preferentially transports large numbers of adult L. littorea, matching the demographic structure of the introduced California L. littorea populations. Our results highlight continued operation of live seafood trade vectors and the influence of vectors on the demographic and genetic structure of the resulting populations, especially early stages of the invasion process

    The 2dF Galaxy Redshift Survey: galaxy clustering per spectral type

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    We have calculated the two-point correlation functions in redshift space, ξ(σ, π), for galaxies of different spectral types in the 2dF Galaxy Redshift Survey. Using these correlation functions, we are able to estimate values of the linear redshift-space distortion parameter, β≡Ω0.6m/b, the pairwise velocity dispersion, a, and the real-space correlation function, ξ(r), for galaxies with both relatively low star formation rates (for which the present rate of star formation is less than 10 per cent of its past averaged value) and galaxies with higher current star formation activity. At small separations, the real-space clustering of passive galaxies is very much stronger than that of the more actively star-forming galaxies; the correlation-function slopes are, respectively, 1.93 and 1.50, and the relative bias between the two classes is a declining function of scale. On scales larger than 10 h−1 Mpc, there is evidence that the relative bias tends to a constant, bpassive/bactive≃ 1. This result is consistent with the similar degrees of redshift-space distortions seen in the correlation functions of the two classes - the contours of ξ(σ, π) require βactive= 0.49 ± 0.13 and βpassive= 0.48 ± 0.14. The pairwise velocity dispersion is highly correlated with β. Despite this, a significant difference is seen between the two classes. Over the range 8-20 h−1 Mpc, the pairwise velocity dispersion has mean values of 416 ± 76 and 612 ± 92 km s−1 for the active and passive galaxy samples, respectively. This is consistent with the expectation from morphological segregation, in which passively evolving galaxies preferentially inhabit the cores of high-mass virialized region

    The 2dF Galaxy Redshift Survey: correlation functions, peculiar velocities and the matter density of the Universe

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    We present a detailed analysis of the two-point correlation function, ξ(σ, π), from the 2dF Galaxy Redshift Survey (2dFGRS). The large size of the catalogue, which contains ∼220 000 redshifts, allows us to make high-precision measurements of various properties of the galaxy clustering pattern. The effective redshift at which our estimates are made is zs≈ 0.15, and similarly the effective luminosity, Ls≈ 1.4L*. We estimate the redshift-space correlation function, ξ(s), from which we measure the redshift-space clustering length, s0= 6.82 ± 0.28 h−1 Mpc. We also estimate the projected correlation function, Ξ(σ), and the real-space correlation function, ξ(r), which can be fit by a power law (r/r0), with r0= 5.05 ± 0.26 h−1 Mpc, γr= 1.67 ± 0.03. For r≳ 20 h−1 Mpc, ξ drops below a power law as, for instance, is expected in the popular Λ cold dark matter model. The ratio of amplitudes of the real- and redshift-space correlation functions on scales of 8-30 h−1 Mpc gives an estimate of the redshift-space distortion parameter β. The quadrupole moment of ξ(σ, π) on scales 30-40 h−1 Mpc provides another estimate of β. We also estimate the distribution function of pairwise peculiar velocities, ƒ(v), including rigorously the significant effect due to the infall velocities, and we find that the distribution is well fit by an exponential form. The accuracy of our ξ(σ, π) measurement is sufficient to constrain a model, which simultaneously fits the shape and amplitude of ξ(r) and the two redshift-space distortion effects parametrized by β and velocity dispersion, a. We find β= 0.49 ± 0.09 and a= 506 ± 52 km s−1, although the best-fitting values are strongly correlated. We measure the variation of the peculiar velocity dispersion with projected separation, a(σ), and find that the shape is consistent with models and simulations. This is the first time that β and ƒ(v) have been estimated from a self-consistent model of galaxy velocities. Using the constraints on bias from recent estimates, and taking account of redshift evolution, we conclude that β (L=L*, z= 0) = 0.47 ± 0.08, and that the present-day matter density of the Universe, Ωm≈ 0.3, consistent with other 2dFGRS estimates and independent analyse

    The 2dF Galaxy Redshift Survey: the nature of the relative bias between galaxies of different spectral type

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    We present an analysis of the relative bias between early- and late-type galaxies in the Two-degree Field Galaxy Redshift Survey (2dFGRS) - as defined by the η parameter of Madgwick et al., which quantifies the spectral type of galaxies in the survey. We calculate counts in cells for flux-limited samples of early- and late-type galaxies, using approximately cubical cells with sides ranging from 7 to 42 h−1 Mpc. We measure the variance of the counts in cells using the method of Efstathiou et al., which we find requires a correction for a finite volume effect equivalent to the integral constraint bias of the autocorrelation function. Using a maximum-likelihood technique we fit lognormal models to the one-point density distribution, and develop methods of dealing with biases in the recovered variances resulting from this technique. We then examine the joint density distribution function, f(δE, δL), and directly fit deterministic bias models to the joint counts in cells. We measure a linear relative bias of ≈1.3, which does not vary significantly with ℓ. A deterministic linear bias model is, however, a poor approximation to the data, especially on small scales (ℓ≤ 28h−1 Mpc) where deterministic linear bias is excluded at high significance. A power-law bias model with index b1≈ 0.75 is a significantly better fit to the data on all scales, although linear bias becomes consistent with the data for ℓ≳ 40h−1 Mp
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