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Effect of particle mixing morphology on aerosol scattering and absorption: A discrete dipole modeling study

AbstractAtmospheric aerosol particles may undergo phase separation due to differences in miscibility. This alters the morphology of particles such that they are no longer well-mixed, simple spheres. As a result, scattering and absorption of sunlight in Earth’s atmosphere could be affected. In turn, this may alter direct climate forcing by aerosols. In this work we examine the impact of phase separation on aerosol optics for the bi-sphere, core–shell, and engulfed morphologies. We find bi-spherical particles often exhibit very different scattering and absorption cross-sections for a mid-visible wavelength (0.53μm) relative to an equivalent, volume-weighted spherical case. Optical differences are largely driven by the particle shape, rather than differences in refractive index between phases. However, when averaged across a typical urban particle size distribution, the differences in light scattering largely vanish and bi-sphere and volume equivalent models generally agreed to within 10% for dielectric particles. For particles that are light absorbing, the bi-sphere and volume averaged cases often yielded dissimilar results with the volume-averaged case reflecting absorption >10% more than the phase separated particles. This was particularly true for bi-spheres in which one component particle is strongly light absorbing. Core–shell and engulfed morphologies yield volume scattering efficiencies within a few percent of volume-weighted spheres. However, modeled light absorption between the phase separated and volume averaged models frequently differ by >20% when inclusions absorb light strongly. Therefore, modeling light absorption of mixed-phase particles through the volume-mixing rule cannot be recommended

Spillway design floods for small dams in rural Missouri

Related publications: "Spillway Design Floods for Small Dams in Rural Missouri," T.E. Harbaugh and J.E. Thompson, Civil Engineering Studies, UMR, Hydrologic Series Bulletin, June, 1970. Two talks were also presented. Student supported: 1 Master's Student, Training for 200 Undergraduates and 25 Graduate Students.At present, 1970, over 1500 small dams exist within the boundaries of the state of Missouri. Estimates indicate the number is growing at the rate of one hundred to two hundred per year. The main factor in possible failure of these existing dams is in an inadequate spillway resulting from poor hydraulic practice and or lack of accurate hydrologic design information. This report presents the result of a state wide analysis of all existing hydrologic data for rural watersheds less than twenty square miles. The results are presented in nomograph form for the 25 and 50 year frequency floods. The report also contains equations for other frequencies at two accuracy levels. The results of this investigation should provide designers of spillways, culverts and bridges with the latest hydrologic flood frequency data for small rural Missouri watersheds.Project # A-025-MO Agreement # 14-31-0001-302

Health status among farm workers in the Western Cape - collateral evidence from a study of occupational hazards

No Abstrac

Pedestrian Solution of the Two-Dimensional Ising Model

The partition function of the two-dimensional Ising model with zero magnetic field on a square lattice with m x n sites wrapped on a torus is computed within the transfer matrix formalism in an explicit step-by-step approach inspired by Kaufman's work. However, working with two commuting representations of the complex rotation group SO(2n,C) helps us avoid a number of unnecessary complications. We find all eigenvalues of the transfer matrix and therefore the partition function in a straightforward way.Comment: 10 pages, 2 figures; eqs. (101) and (102) corrected, files for fig. 2 fixed, minor beautification

Accurately quantifying the shape of birds’ eggs

Describing the range of avian egg shapes quantitatively has long been recognized as difficult. A variety of approaches has been adopted, some of which aim to capture the shape accurately and some to provide intelligible indices of shape. The objectives here are to show that a (four‐parameter) method proposed by Preston (1953, The Auk, 70, 160) is the best option for quantifying egg shape, to provide and document an R program for applying this method to suitable photographs of eggs, to illustrate that intelligible shape indices can be derived from the summary this method provides, to review shape indices that have been proposed, and to report on the errors introduced using photographs of eggs at rest rather than horizontal

Nursing teamwork in the care of older people: A mixed methods study

Healthcare is increasingly complex and requires the ability to adapt to changing demands. Teamwork is essential to delivering high quality care and is central to nursing. The aims of this study were to identify the processes that underpin nursing teamwork and how these affect the care of older people, identify the relationship between perceived teamwork and perceived quality of care, and explore in depth the experience of working in nursing teams. The study was carried out in three older people's wards in a London teaching hospital. Nurses and healthcare assistants completed questionnaires (n=65) on known dynamics of teamwork (using the Nursing Teamwork Survey) together with ratings of organisational quality (using an adapted AHRQ HSPS scale). A sample (n=22; 34%) was then interviewed about their perceptions of care, teamwork and how good outcomes are delivered in everyday work. Results showed that many care difficulties were routinely encountered, and confirmed the importance of teamwork (e.g. shared mental models of tasks and team roles and responsibilities, supported by leadership) in adapting to challenges. Perceived quality of teamwork was positively related to perceived quality of care. Work system variability and the external environment influenced teamwork, and confirmed the importance of team adaptive capacity. The CARE model shows the centrality of teamwork in adapting to variable demand and capacity to deliver care processes, and the influence of broader system factors on teamworking

Ground--state energies and widths of 5^5He and 5^5Li

We extract energies and widths of the ground states of $^5$He and $^5$Li from recent single--level R--matrix fits to the spectra of the $^3$H$({\rm d},\gamma$)$^5$He and the $^3$He$({\rm d},\gamma$)$^5$Li reactions. The widths obtained differ significantly from the formal R--matrix values but they are close to those measured as full widths at half maxima of the spectra in various experiments. The energies are somewhat lower than those given by usual estimates of the peak positions. The extracted values are close to the S--matrix poles calculated previously from the multi--term analyses of the N-$^4$He elastic scattering data.Comment: 3 pages, no figures, uses revtex.sty, accepted for publication in PRC, uuencoded postscript and tex-files available at ftp://is1.kph.tuwien.ac.at/pub/ohu/fwidth.u

Feature selection through validation and un-censoring of endovascular repair survival data for predicting the risk of re-intervention

Background: Feature selection (FS) process is essential in the medical area as it reduces the effort and time needed for physicians to measure unnecessary features. Choosing useful variables is a difficult task with the presence of censoring which is the unique characteristic in survival analysis. Most survival FS methods depend on Cox's proportional hazard model; however, machine learning techniques (MLT) are preferred but not commonly used due to censoring. Techniques that have been proposed to adopt MLT to perform FS with survival data cannot be used with the high level of censoring. The researcher's previous publications proposed a technique to deal with the high level of censoring. It also used existing FS techniques to reduce dataset dimension. However, in this paper a new FS technique was proposed and combined with feature transformation and the proposed uncensoring approaches to select a reduced set of features and produce a stable predictive model. Methods: In this paper, a FS technique based on artificial neural network (ANN) MLT is proposed to deal with highly censored Endovascular Aortic Repair (EVAR). Survival data EVAR datasets were collected during 2004 to 2010 from two vascular centers in order to produce a final stable model. They contain almost 91% of censored patients. The proposed approach used a wrapper FS method with ANN to select a reduced subset of features that predict the risk of EVAR re-intervention after 5 years to patients from two different centers located in the United Kingdom, to allow it to be potentially applied to cross-centers predictions. The proposed model is compared with the two popular FS techniques; Akaike and Bayesian information criteria (AIC, BIC) that are used with Cox's model. Results: The final model outperforms other methods in distinguishing the high and low risk groups; as they both have concordance index and estimated AUC better than the Cox's model based on AIC, BIC, Lasso, and SCAD approaches. These models have p-values lower than 0.05, meaning that patients with different risk groups can be separated significantly and those who would need re-intervention can be correctly predicted. Conclusion: The proposed approach will save time and effort made by physicians to collect unnecessary variables. The final reduced model was able to predict the long-term risk of aortic complications after EVAR. This predictive model can help clinicians decide patients' future observation plan