2,984 research outputs found
Alternative approaches to multilevel modelling of survey non-contact and refusal
No full textWe review three alternative approaches to modelling survey non-contact and refusal: multinomial, sequential, and sample selection (bivariate probit) models. We then propose a multilevel extension of the sample selection model to allow for both interviewer effects and dependency between non-contact and refusal rates at the household and interviewer level. All methods are applied and compared in an analysis of household non-response in the United Kingdom, using a data set with unusually rich information on both respondents and non-respondents from six major surveys. After controlling for household characteristics, there is little evidence of residual correlation between the unobserved characteristics affecting non-contact and refusal propensities at either the household or the interviewer level. We also find that the estimated coefficients of the multinomial and sequential models are surprisingly similar, which further investigation via a simulation study suggests is due to non-contact and refusal having largely different predictor
Analysing interviewer call record data to understand the process leading to cooperation or refusal
No full textAnalysing the process leading to cooperation or refusal using call record data: A multilevel multinomial modelling approach
No full textIn recent years, survey agencies have started to collect detailed call record data, including information on the timing and outcome of each interviewer call to a household. In interviewbased household surveys, effective interviewer calling behaviours are critical in achieving cooperation and reducing the likelihood of refusal. This paper aims to analyze interviewer call record data to inform the process leading to cooperation or refusal in face-to-face surveys. Of particular interest are the influences on the outcome of a call of interactions between the interviewer and householder and of time-varying characteristics of the call. A multilevel multinomial logistic regression approach is used in which the different possible outcomes at each call are modelled jointly
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No full textHere is a curious book. Its title-page declares "The Artist's Book of Fables" but its pre-title-page has "Fables, Original and Selected, with a Memoir of the Author." After that title-page, it is identical with "Fables, Original and Selected" as in our copy printed by John Murray in 1833. There is again an AI at the front and an index of engravings and engravers at the back. I found that copy twenty years ago. I had found an inferior copy twenty-two years before that. At that time, I noted Aesopic fables here including "Stone Broth" and "The Mouse and the Oyster."This is a hardbound book (hard cover)James Northcote, R.A
Turbulent entrainment in a shearless mixing layer at the edge of a cloud
No full textThree-dimensional direct numerical simulations which combine the Eulerian description of temperature, vapor content and velocity with a Lagrangian ensemble of cloud water droplets are used to study the turbulent entrainment and subsequent mixing of clear air with a cloudy air filament. The study is conducted in a shearless mixing layer setup which is adjusted to realistic conditions at a cumulus cloud boundary. The magnitude of turbulent velocity fluctuations in- and outside the cloud can be varied independently. We find that the evolution of the cloud water droplet ensemble depends slightly only on the contrast of turbulent velocity fluctuations in- and outside the cloud filament. The buoyancy feedback on the flow via the evaporating droplets causes a transient amplification of all fluctuations before the turbulence eventually decays. We study the evolution of the probability density functions of droplet size as well as of supersaturation, temperature and vorticity at the droplet positions
Dimension-adaptive bounds on compressive FLD Classification
No full textEfficient dimensionality reduction by random projections (RP) gains popularity, hence the learning guarantees achievable in RP spaces are of great interest. In finite dimensional setting, it has been shown for the compressive Fisher Linear Discriminant (FLD) classifier that forgood generalisation the required target dimension grows only as the log of the number of classes and is not adversely affected by the number of projected data points. However these bounds depend on the dimensionality d of the original data space. In this paper we give further guarantees that remove d from the bounds under certain conditions of regularity on the data density structure. In particular, if the data density does not fill the ambient space then the error of compressive FLD is independent of the ambient dimension and depends only on a notion of ‘intrinsic dimension'
Flyleaf of The Village Politicians, signed by author and publisher R.A. Parsons, and printed by Guardian Ltd.
No full textNewIntroduction. Flyleaf of the The Village Politicans by R.A. Parsons and printed by Guardian Ltd.DA vol. 15 no.
Non-Linear Time Series Analysis of Deep Groundwater Levels: An application to the Veluwe
No full textThe objective of this study is to improve the simulation of deep groundwater levels by time se- ries models with pre-defined impulse response functions. This is attempted by adding a conceptual non-linear root zone model to simulate the recharge series to the model and by testing the use of a separate response function for the percolation zone. Three root zone models are developed based on two different recharge mechanisms: preferential flow, percolation, and a combination of the two. The performance of these models is compared to a linear model that is commonly used in time se- ries models to simulate the recharge. The approach is applied to groundwater level measurements in the Veluwe, a largely forested area in the Netherlands characterized by thick unsaturated zones. The effect of groundwater extractions and land reclamations is added to the model to further im- prove the simulation of the groundwater levels. The models are tested on three observations wells with increasing thickness of the unsaturated zone, varying from 7 m to 29 m to 49 m. The results show that model performance is improved by the implementation of a non-linear root zone model, particularly in simulating the peaks and lows in the groundwater levels. The recharge fluxes simulated by the non-linear models show different patterns that are physically more realistic than those simulated by the linear model. It is shown that different recharge series result in simulated groundwater levels that are very similar. This is a clear example of equifinality and it is recommended to introduce new sources of information to validate the modelled processes (e.g., water content measurements of the percolation zone or actual evaporation data). For the shallow well, the models with a single response function are selected as the best. The largest improvements for the deeper groundwater levels are obtained by the addition of a separate response for the percolation zone. For example, the average deviation from the observed ground- water levels decreased 0.18 m to 0.08 m for the deepest observation well by applying the separate response function. The models with an additional response function were better at simulating the estimated time to peak, the time it takes a recharge pulse to cause a peak in the groundwater levels. The time to peak is introduced in this research as a qualitative indicator to validate the modelled processes. The simulated responses indicate that the groundwater levels respond very quickly to water that leaves the root zone, even though the percolation zone is tens of metres thick. For each of the observations wells it is investigated if adding the effect of groundwater extrac- tions or land reclamations of Flevoland to the models improves the simulation of the groundwater levels. For the shallow well it is concluded that either the effect of land reclamations or groundwater extractions needs to be taken into account. Since these two stresses are correlated, it is concluded that only one of these should be taken into account when no further information is available to con- strain the models. For the medium deep well, the additional stresses did not significantly improve model performance and it is concluded that they do not have to be taken into account for this well. For the deep well, model performance is improved by both stresses. The largest improvements are observed when the effect of groundwater extractions is considered in the model. For implemen- tation of these stresses, the entire simulation period should be used for calibration, or constraints have to be implemented to obtain realistic results.Water ResourcesWater ManagementCivil Engineering and Geoscience
Chemicals from renewable biomass: A renaissance in carbohydrate chemistry
No full textThe conversion of sugars, derived from waste polysaccharide biomass, to commodity chemicals by fermentation or catalytic hydrogenation, oxidation or dehydration or combinations thereof are reviewed.Accepted Author ManuscriptBT/Biocatalysi
Growth Of Lignocellulosic-fermenting Fungi On Different Substrates Under Low Oxygenation Conditions
No full textFour soil fungi able to grow under low oxygenation conditions were selected and used in studies to determine the production of enzymes that promote the degradation of lignocellulosic materials. The capacity of these fungi to ferment such materials was also investigated. The fungi were grown in sugarcane bagasse and sawdust at final concentrations of 4 and 10%, as the carbon sources. The strains were cultivated under microaerophilic and combined conditions of oxygenation (aerobic followed by microaerophilic conditions). The results obtained with the basidiomycete specie, Trichocladium canadense, Geotrichum sp., and Fusarium sp. suggest that they prefer lower oxygen concentration for growth and enzyme production. Lignocellulolytic activities were detected in all strains but varied with the carbon source used. The highest levels of these activities were produced by the Basidiomycete specie and Fusarium sp. Ethanol and other nongaseous fermentation products were detected following high-performance liquid chromatography analysis using a supelcogel C-610H column, demonstrating the fermentative capability of these strains. In view of their ability to produce enzymes necessary for the breakdown of lignocellulosic materials and to utilize most of the degradation products for growth, these strains have a great potential for biotechnological application.98-100663677Wyman, C.E., (1994) Bioresour. Technol., 50, pp. 3-16Wyman, C.E., (1996) Handbook on Bioethanol: Production and Optimization, pp. 1-18. , Wyman, C. E., ed., Taylor and FrancisNikolov, T., Bakalova, N., Petrova, S., Benadova, R., Spasov, Kolev, D., (2000) Bioresour. Technol., 71, pp. 1-4Bhat, M.K., Bhat, S., (1997) Biotechnol. Adv., 15, pp. 583-620Pandey, A., Soccol, C.R., Nigam, P., Soccol, V., (2000) Bioresour. Technol., 74, pp. 69-80Coughlan, M.P., (1992) Bioresour. Technol., 39, pp. 107-115Beguin, P., Aubert, J.P., (1994) FEMS Microbiol. Rev., 13, pp. 25-58Himmel, M.E., Adney, W.S., Baker, J.O., Nieves, R.A., Thomas, S.R., (1996) Handbook on Bioethanol: Production and Optimization, pp. 143-162. , Wyman, C.E., ed., Taylor and FrancisBrigham, J., Adney, W.S., Himmel, M.E., (1996) Handbook on Bioethanol: Production and Optimization, pp. 119-142. , Wyman, C.E., ed., Taylor and FrancisMouchacca, J., (1997) Crypt. Mycol., 18, pp. 19-69Kaal, E.J., De Jong, E., Field, J.A., (1993) Appl. Environm. Microbiol., 59, pp. 4031-4036Lee, J., (1997) J. Biotechnol., 56, pp. 1-24Zeikus, J.G., (1990) Lignin Biodegradation: Microbiology, Chemistry and Potential Applications, 1. , Kirk, T. K., Higuchi, T., and Chang, H-M., eds., CRC Press, Boca Raton, FLBlanchette, R.A., (2000) Intern. Biodeter. Biodegrad., 46, pp. 189-204Singh, A., Kumar, P.K., Schuger, K., (1992) Biotechnol. Appl. Biochem., 16, pp. 296-302Durrant, L.R., Canale-Parola, E., Leschine, S.B., (1995) The Significance and Regulation of Soil Biodiversity, pp. 161-167. , Collins, H. P., Robertson, G. P., and Klug, M. J., eds., Kluwer Academic, The NetherlandsMiller, G.L.R., (1959) Anal. Biochem., 31, pp. 426-429Tien, M., Kirk, T.K., (1984) Proc. Natl. Acad. Sci. USA, 81, pp. 2280-2284Kuwahara, M., Glenn, J.K., Morgan, M.A., Gold, M.H., (1984) FEBS Lett., 169, pp. 247-250Szklark, G.D., Antibus, R.K., Sinsabaugh, R.L., Linkins, A.E., (1989) Mycology, 81, pp. 234-240Messner, R., Kubicek, C., (1991) Appl. Environ. Microbiol., 57, pp. 630-635Tuor, U., Winterhalter, K., Fiechter, A., (1995) J. Biotechnol., 41, pp. 1-17Pavarina, E.C., Sette, L.D., Anazawa, T.A., Durrant, L.R., (1999) Appl. Biochem. Biotechnol., 82, pp. 153-163Brune, A., Frenzel, P., Cypionka, H., (2000) FEMS Microbiol. Rev., 24, pp. 691-710Eiteman, M.A., Chastain, M.J., (1997) Anal. Chim. Acta, 338, pp. 69-7
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