Modeling electrokinetic flows with the discrete ion stochastic continuum overdamped solvent algorithm.

In this article we develop an algorithm for the efficient simulation of electrolytes in the presence of physical boundaries. In previous work the discrete ion stochastic continuum overdamped solvent (DISCOS) algorithm was derived for triply periodic domains, and was validated through ion-ion pair correlation functions and Debye-Hückel-Onsager theory for conductivity, including the Wien effect for strong electric fields. In extending this approach to include an accurate treatment of physical boundaries we must address several important issues. First, the modifications to the spreading and interpolation operators necessary to incorporate interactions of the ions with the boundary are described. Next we discuss the modifications to the electrostatic solver to handle the influence of charges near either a fixed potential or dielectric boundary. An additional short-ranged potential is also introduced to represent interaction of the ions with a solid wall. Finally, the dry diffusion term is modified to account for the reduced mobility of ions near a boundary, which introduces an additional stochastic drift correction. Several validation tests are presented confirming the correct equilibrium distribution of ions in a channel. Additionally, the methodology is demonstrated using electro-osmosis and induced-charge electro-osmosis, with comparison made to theory and other numerical methods. Notably, the DISCOS approach achieves greater accuracy than a continuum electrostatic simulation method. We also examine the effect of under-resolving hydrodynamic effects using a "dry diffusion" approach, and find that considerable computational speedup can be achieved with a negligible impact on accuracy.

European Space Agency experiments on thermodiffusion of fluid mixtures in space.

This paper describes the European Space Agency (ESA) experiments devoted to study thermodiffusion of fluid mixtures in microgravity environment, where sedimentation and convection do not affect the mass flow induced by the Soret effect. First, the experiments performed on binary mixtures in the IVIDIL and GRADFLEX experiments are described. Then, further experiments on ternary mixtures and complex fluids performed in DCMIX and planned to be performed in the context of the NEUF-DIX project are presented. Finally, multi-component mixtures studied in the SCCO project are detailed.

General Blending Models for Data From Mixture Experiments.

We propose a new class of models providing a powerful unification and extension of existing statistical methodology for analysis of data obtained in mixture experiments. These models, which integrate models proposed by Scheffé and Becker, extend considerably the range of mixture component effects that may be described. They become complex when the studied phenomenon requires it, but remain simple whenever possible. This article has supplementary material online.

Multifunctional composites: optimizing microstructures for simultaneous transport of heat and electricity.

Composite materials are ideally suited to achieve multifunctionality since the best features of different materials can be combined to form a new material that has a broad spectrum of desired properties. Nature's ultimate multifunctional composites are biological materials. There are presently no simple examples that rigorously demonstrate the effect of competing property demands on composite microstructures. To illustrate the fascinating types of microstructures that can arise in multifunctional optimization, we maximize the simultaneous transport of heat and electricity in three-dimensional, two-phase composites using rigorous optimization techniques. Interestingly, we discover that the optimal three-dimensional structures are bicontinuous triply periodic minimal surfaces.

Crossover designs with correlated observations.

Crossover designs are widely used in different medical investigations where a number of treatments have to be compared. Sequences of treatments are given to subjects, and in practice the observations within each subject are likely to be correlated. This paper is concerned with the construction of crossover designs for such cases. The design problem is nonlinear in the parameters, and design optimality depends on the parameters defining the correlation structure. When the correlation structure is known, local optimum designs are obtained. When the distribution of its parameters is known, optimum Bayesian crossover designs are constructed. The optimum sizes of the groups of subjects receiving the same sequence of treatments are also determined.

Modelling and design of cross-over trials.

There are many diseases and conditions that can be studied using a cross-over clinical trial, where the subjects receive sequences of treatments. The treatments are then compared using the repeated measurements taken 'within' subjects. The actual plan or design of the trial is usually obtained by consulting a published table of designs or by applying relatively simple rules such as using all possible permutations of the treatments. However, there is a danger is this approach because the model assumed for the data when the tables or rules were constructed may not be appropriate for the new trial being planned. Also, there may be restrictions in the new trial on the number of treatment sequences that can be used or on the number of periods of treatment particular subjects can be given. Such restrictions may mean that a published design of the ideal size cannot be found unless compromises are made. A better approach is to make the design satisfy the objectives of the trial rather than vice versa. In this paper we describe an approach to constructing such tailor-made designs which we hope will lead to ill-fitting 'off the peg' designs being a thing of the past. We use a computer algorithm to search for optimal designs and illustrate it using a number of examples. The criterion of optimality used in this paper is A-optimality but our approach is not restricted to one particular criterion. The model used in the search for the optimal design is chosen to suit the nature of the trial at hand and as an example a variety of models for three treatments are considered. We also illustrate the construction of designs for the comparison of two active treatments and a placebo where it can be assumed that the carry-over effects of the active treatments are similar. Finally, we illustrate an augmentation of a design that could arise when the objectives of a trial change.

[Studies of the etiology of infectious abortion in cows in Ruse District]. / Prouchvaniia vurkhu etiologiiata na infektsioznite aborti po kravite v Rusenski okrug.

A total of 28,159 blood serum samples have been examined for brucellosis, 87--for leptospirosis, 84--for toxoplasmosis, 554--for the presence of rickettsii and neoreckettsii, and 193--for total protein content, albumin, and protein fractions, taken from cows in the course of the years on 40 dairy farms in the district of Rousse. Bacteriologically were examined 349 aborted fetuses, 178 samples of estral secretion, 57 placentae, and 1002 samples of washings and seminal fluid from bulls for vibriosis. Bacteriologic investigations were also carried out on 383 fetuses for salmonellosis, listeriosis, and colibacteriosis, and virologic studies of 398 placentae and parenchymal organs of fetuses. Twenty-eight fetuses were studied parasitologically for toxoplasmosis, and 118 blood smears were examined for hemosporidiosis. It was established that most important in the etiology of the infectious abortions in cows in the district of Rousse were Vibrio organisms. They were found in 36.9 per cent of the studied bovine fetuses and in 24.4 per cent of all materials examined bacteriologically. Only 4 cases were noted of neorickettsii from fetuses and placentae. Serologically, there were 23.6 per cent cases positive for neorickettsiosis, and 12.6 per cent--for Q fever; 56.4 per cent of the investigated sera proved positive for leptospirosis. In 0.8 per cent of the examined fetuses there was Escherichia coli. Abortions in cows were also due to anaplasmosis and francaillelosis; 14.2 per cent of the investigated respective sera were positive for toxoplasmosis. On the days of abortions the amount of total protein was 7.13 mg%, that of albumins--36%, and of globulins--64%. It is considered imperative to elucidate the cause of abortions of infectious nature in cows in connection with the establishing of cattle-breeding complexes.

[Epizootiological and parasitological status of the flocks at a poultry combine]. / Vurkhu epizootologichniia i parazitologichniia status na stadata v edin ptitsekombinat

A comprehensive epizootiologic study has been carried out at one of the large poultry dressing combines in this country. Results have shown that the part played by infections as against the remaining diseases established in the various technologic categories is as follows: 9 to 23.8 per cent in growing parents; 16.0 to 24.6 per cent in adult parents; and 4.8 to 13.4 per cent in broilers. So far as parasitic diseases are concerned the respective figures are 3.2 to 9.9 per cent, 3.0 to 3.3. per cent, and 2.9 to 3.0 to per cent. The import of birds from France and England intended for satisfying the needs of the poultry dressing combine in Roussé has contributed to the introduction of infections which have later on assumed an epizootic course, such as infections encephalomyelitis, infectious bronchitis, and Marek' disease. The epizootic status has been aggravated with the development of a number of diseases already existing in this country--fowl pox, lymphoid leukosis, chronic respiratory disease, salmonellosis, and above all infections caused by the so-called occasionally pathogenic agents--coli organisms, staphylococci, and Pseudomonas. Of the parasitic diseases only coccidiosis has developed, being caused by a variety of species: Eimeria acervulina, Eimeria necatrix, Eimeria maxima, Eimeria muvati and Eimeria tenella. The absence of helminth infections is due to the routinely adopted technological practice of raising birds in confinement and the strict veterinary control and guard. On the basis of the results obtained and the conclusions drawn some more effective prophylactic measures are suggested correcting and supplementing the existing prophylactic programme.

[Study of the outcome of pregnancy in sheep with positive serologic reactions to toxoplasmosis according to the complement fixation test]. / Prouchvaniia v'rkhu izkhoda na bremennostta pri ovtse, serologichno reagirali polozhitelno za toksoplazmoza po RSK

Studied were five flocks of 240 sheep each. It was found that prior to impregnation the positive complement-fixation test (c. f. test) reagents varied from 16 to 61 per cent with titers ranging from 1:50 to 1:10. Abortions, however, were established only in two of the flocks consisting of young sheep, aged 3 and 4 years, at the first or second lambing. The abortions took place in the fourth month of pregnancy. In one of these flocks having 43 per cent positive reagents there were 40 per cent returns, and 28 of the ewes miscarried, 12 of them being positive for toxoplasmosis. In the second flock there were 61 per cent positive reagents, and 9 of the ewes miscarried, 5 of them being positive for toxoplasmosis. In the remaining three flocks consisting of 5-year-old sheep there were no abortions. The ewes that miscarried and were positive for toxoplasmosis showed a rise in their serum titers: from 1:40 on the 15th day after the abortion to 1:80 on the 30th day. It is believed that in these sheep the abortions are not due to toxoplasmosis, and in sheep flocks with a high percent of positive toxoplasmosis reagnets there may not be abortions.

[Isolation of Toxoplasma strains via the digestive method]. / Izolirane na shtamove toksoplazmi chrez digestivniia metod

Tested was the effectiveness of the digestive method for the isolation of Toxoplasma strains. This method was used to study the musculature of the diaphragm in 80 sheep, 40 cattle, and 80 pigs. Isolated were one strain that was pathogenic and 3 apathogenic strains for albino mice. They were found only in the diaphragm of sheep. It is believed that the digestive method is effective for the isolation of Toxoplasma strains.