225 research outputs found

    The last voyages of Firefly and Captain Kirby

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    Independent predictors of breastfeeding intention in a disadvantaged population of pregnant women

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    Background: Breastfeeding rates in Scotland are very low, particularly in the more disadvantaged areas. Despite a number of interventions to promote breastfeeding very few women actually intend to breastfeed their baby. The aim of this study was to identify personal and social factors independently associated with intention to breastfeed. Methods: Nine hundred and ninety seven women from two socio-economically disadvantaged housing estates located on the outskirts of Glasgow participated in a study that aimed to increase the prevalence of breastfeeding. Self-administered questionnaires completed by each participant collected information in early pregnancy, prior to exposure to the study intervention, on feeding intention, previous feeding experience and socio-demographic data. Results: Five factors were independently predictive of breastfeeding intention. These were previous breastfeeding experience, living with a partner, smoking, parity and maternal age. After adjusting for these five factors, neither deprivation nor receipt of milk tokens provided useful additional predictive information. Conclusion: In this population of socially disadvantaged pregnant women we identified five variables that were independently predictive of breastfeeding intention. These variables could be useful in identifying women at greatest risk of choosing not to breastfeed. Appropriate promotional efforts could then be designed to give due consideration to individual circumstances

    Verification of German methane emission inventories and their recent changes based on atmospheric observations

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    Continuous methane concentration records and stable isotope observations measured in the suburbs of Heidelberg, Germany, are presented. While delta13C-CH4 shows a significant trend of -0.14 permil per year, towards more depleted values, no trend is observed in the concentration data. Comparison of the Heidelberg records with clean air observations in the North Atlantic at Izana station (Tenerife) allows the determination of the continental methane excess at Heidelberg, decreasing by 20% from 190 ppb in 1992 to 150 ppb in 1997. The isotope ratio which is associated with this continental methane pile-up in the Heidelberg catchment area shows a significant trend to more depleted values from delta13C (source) = -47.4 ± 1.2 permil in 1992 to 52.9 ± 0.4 permil in 1995/96, pointing to a significant change in the methane source mix. Total methane emissions in the Heidelberg catchment area are estimated using the 222Radon (222Rn) tracer method: from the correlations of half hourly 222Rn and CH4 mixing ratios from 1995 to 1997, and the mean 222Rn exhalation rate from typical soils in the Rhine valley, a mean methane flux of 0.24 ± 0.5 g CH4 km-2 s-1 is derived. For the Heidelberg catchment area with an estimated radius of approximately 150 km, Core Inventories Air 1990 (CORINAIR90) emission estimates yield a flux of 0.47 g CH4 km-2 s-1, which is about 40% higher than the 222Rn derived number if extrapolated to 1990. The discrepancy can be explained by over-estimated emissions from waste management in the CORINAIR90 statistical assessment. The observed decrease in total emissions can be accounted for by decreasing contributions from fossil sources (mainly coal mining) and from cattle breeding. This finding is also supported by the observed decrease in mean source isotopic signatures

    Masking Ability of Zirconia with and without Veneering Porcelain

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    Purpose : The present study compared changes in CIE L*a*b* color coordinates of substrates of different colors when covered with zirconium oxide discs (Procera) and with such discs if veneered with two shades of porcelain. Material and Methods : Forty background substrates were fabricated and divided into four groups depending on the color of the substrates: white, black, gray, and tooth‐colored (Vita shade A3). The initial color of the substrates was measured using a colorimeter. The color of the substrates covered with plain zirconium oxide discs and with zirconium oxide discs veneered with porcelains of two shades (Vita shade A1 and B4) was measured. The color difference between the substrates, the substrates covered with plain discs, and the substrates covered with veneered discs was calculated, and the data were statistically analyzed with one‐way ANOVA and multiple paired t ‐test. Results : For each group of substrates, the resulting colors were significantly different when the substrates were covered by either plain zirconium oxide discs or zirconium oxide discs veneered with Vita shade A1 or B4 porcelain. Conclusion : While zirconium oxide coping material alone has a degree of masking ability, the resulting color of a restoration can be further modified with the veneering porcelain.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96301/1/j.1532-849X.2012.00915.x.pd

    Collocation analysis for UMLS knowledge-based word sense disambiguation

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    BACKGROUND: The effectiveness of knowledge-based word sense disambiguation (WSD) approaches depends in part on the information available in the reference knowledge resource. Off the shelf, these resources are not optimized for WSD and might lack terms to model the context properly. In addition, they might include noisy terms which contribute to false positives in the disambiguation results. METHODS: We analyzed some collocation types which could improve the performance of knowledge-based disambiguation methods. Collocations are obtained by extracting candidate collocations from MEDLINE and then assigning them to one of the senses of an ambiguous word. We performed this assignment either using semantic group profiles or a knowledge-based disambiguation method. In addition to collocations, we used second-order features from a previously implemented approach.Specifically, we measured the effect of these collocations in two knowledge-based WSD methods. The first method, AEC, uses the knowledge from the UMLS to collect examples from MEDLINE which are used to train a Naïve Bayes approach. The second method, MRD, builds a profile for each candidate sense based on the UMLS and compares the profile to the context of the ambiguous word.We have used two WSD test sets which contain disambiguation cases which are mapped to UMLS concepts. The first one, the NLM WSD set, was developed manually by several domain experts and contains words with high frequency occurrence in MEDLINE. The second one, the MSH WSD set, was developed automatically using the MeSH indexing in MEDLINE. It contains a larger set of words and covers a larger number of UMLS semantic types. RESULTS: The results indicate an improvement after the use of collocations, although the approaches have different performance depending on the data set. In the NLM WSD set, the improvement is larger for the MRD disambiguation method using second-order features. Assignment of collocations to a candidate sense based on UMLS semantic group profiles is more effective in the AEC method.In the MSH WSD set, the increment in performance is modest for all the methods. Collocations combined with the MRD disambiguation method have the best performance. The MRD disambiguation method and second-order features provide an insignificant change in performance. The AEC disambiguation method gives a modest improvement in performance. Assignment of collocations to a candidate sense based on knowledge-based methods has better performance. CONCLUSIONS: Collocations improve the performance of knowledge-based disambiguation methods, although results vary depending on the test set and method used. Generally, the AEC method is sensitive to query drift. Using AEC, just a few selected terms provide a large improvement in disambiguation performance. The MRD method handles noisy terms better but requires a larger set of terms to improve performance

    A randomized attitude slew planning algorithm for autonomous spacecraft

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    The ability to autonomously generate and execute large angle attitude maneuvers, while operating under a number of celestial and dynamical constraints, is a key factor in the development of several future space platforms. In this paper we propose a ran-domized attitude slew planning algorithm for autonomous spacecraft, which is able to address a variety of pointing constraints, including bright object avoidance and ground link maintenance, as well as constraints on the control inputs and spacecraft states, and integral constraints such as those deriving from thermal control requirements. Moreover, through the scheduling of feedback control policies, the algorithm provides a consistent decoupling between low-level control and attitude motion planning, and is robust with respect to uncertainties in the spacecraft dynamics and environmental disturbances. Sim-ulation examples are presented and discussed

    Wet and dry sizes of atmospheric aerosol particles: An AFM‐TEM Study

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    We studied the hygroscopic behavior of atmospheric aerosols by using a novel approach, the combination of atomic force microscopy (AFM) with transmission electron microscopy (TEM) imaging of the same individual particles. By comparing the dimensions of hydrated and dry ammonium sulfate particles collected above the North Atlantic Ocean, we determined that particle volumes are up to four times larger under ambient conditions (as determined by AFM) than in the vacuum of a transmission electron microscope. We interpret these changes as resulting from the loss of water. Organic films on the particles may be responsible for the relatively large water uptake at low relative humidities
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