Regular Mixture Research Articles

Modelling group dynamic animal movement

Summary Group dynamics are a fundamental aspect of many species' movements. The need to adequately model individuals' interactions with other group members has been recognized, particularly in order to differentiate the role of social forces in individual movement from environmental factors. However, to date, practical statistical methods, which can include group dynamics in animal movement models, have been lacking. We consider a flexible modelling framework that distinguishes a group‐level model, describing the movement of the group's centre, and an individual‐level model, such that each individual makes its movement decisions relative to the group centroid. The basic idea is framed within the flexible class of hidden Markov models, extending previous work on modelling animal movement by means of multistate random walks. While in simulation experiments parameter estimators exhibit some bias in non‐ideal scenarios, we show that generally the estimation of models of this type is both feasible and ecologically informative. We illustrate the approach using real movement data from 11 reindeer (Rangifer tarandus). Results indicate a directional bias towards a group centroid for reindeer in an encamped state. Though the attraction to the group centroid is relatively weak, our model successfully captures group‐influenced movement dynamics. Specifically, as compared to a regular mixture of correlated random walks, the group dynamic model more accurately predicts the non‐diffusive behaviour of a cohesive mobile group. As technology continues to develop, it will become easier and less expensive to tag multiple individuals within a group in order to follow their movements. Our work provides a first inferential framework for understanding the relative influences of individual versus group‐level movement decisions. This framework can be extended to include covariates corresponding to environmental influences or body condition. As such, this framework allows for a broader understanding of the many internal and external factors that can influence an individual's movement.

Hydrodynamics of Liquid-Solid Semi-fluidized Bed with Regular Homogenous Ternary Mixture

Hydrodynamics studies in Semi-fluidized bed relating to bed pressure drop, height of top packed bed, minimum and maximum semi-fluidization velocities with regular (spherical glass beads) homogeneous ternary mixtures, have been made in 0.01, 0.025, 0.037, 0.05, and 0.065 m internal diameter Perspex columns, with water as the fluidizing medium. Ternary mixtures of glass beads of different sizes (-8+10, -10+12 and -12+14 BSS) have been used as the semi-fluidized solids. Experimental studies relate to establish the effect of system parameters viz. column diameter, average particle size of semi-fluidized solid and initial static bed height and operating parameters viz. superficial liquid velocity and bed expansion ratio on the above mentioned system variables. Empirical and semi-empirical models have been developed using dimensional as well as statistical analyses. The calculated values from the predicted models have been compared with their experimental counterparts and fairly good agreement has been obtained. The results have also been compared with those available in the literature for irregular homogenous ternary mixtures.

Diversity of potential hydrogen bonds in cellulose I revealed by molecular dynamics simulation

We have performed molecular dynamics calculations using a revised version of the Gromos56Acarbo force field to understand the consequences of the different potential hydrogen bonding patterns on the structural stability and thermal behavior of the Iα and Iβ forms of native cellulose. For each allomorph, we considered three patterns of hydrogen bonds: two patterns obtained from neutron diffraction data refinement and a regular mixture of the two. Upon annealing, the hydrogen bonding schemes of cellulose Iβ, irrespective of the starting structure, re-arranged into the main hydrogen bond pattern experimentally observed (pattern A). On the other hand, the Iα structures, irrespective of the starting hydrogen bonding pattern, converged to a non-experimental structure where the adjacent chains are shifted along the chain direction by 0.12 nm in the hydrogen-bonded plane, and the hydroxymethyl group conformation alternates between gt and tg along the chain. The exotic structure in Iα might be a consequence of a deficiency in force field parameters and/or potential molecular arrangement in less crystalline cellulose.

CHull as an alternative to AIC and BIC in the context of mixtures of factor analyzers

Mixture analysis is commonly used for clustering objects on the basis of multivariate data. When the data contain a large number of variables, regular mixture analysis may become problematic, because a large number of parameters need to be estimated for each cluster. To tackle this problem, the mixtures-of-factor-analyzers (MFA) model was proposed, which combines clustering with exploratory factor analysis. MFA model selection is rather intricate, as both the number of clusters and the number of underlying factors have to be determined. To this end, the Akaike (AIC) and Bayesian (BIC) information criteria are often used. AIC and BIC try to identify a model that optimally balances model fit and model complexity. In this article, the CHull (Ceulemans & Kiers, 2006) method, which also balances model fit and complexity, is presented as an interesting alternative model selection strategy for MFA. In an extensive simulation study, the performances of AIC, BIC, and CHull were compared. AIC performs poorly and systematically selects overly complex models, whereas BIC performs slightly better than CHull when considering the best model only. However, when taking model selection uncertainty into account by looking at the first three models retained, CHull outperforms BIC. This especially holds in more complex, and thus more realistic, situations (e.g., more clusters, factors, noise in the data, and overlap among clusters).

Intraoperative conditions and quality of postoperative analgesia after adding dexmedetomidine to epidural bupivacaine and fentanyl in elective cesarean section using combined spinal-epidural anesthesia.

This study was designed to evaluate the effect of adding dexmedetomidine to regular mixture of epidural drugs for pregnant women undergoing elective cesarean section with special emphasis on their sedative properties, ability to improve quality of intraoperative, postoperative analgesia, and neonatal outcome.Materials and Methods:Fifty women of ASA physical status I or II at term pregnancy were enrolled randomly to receive plain bupivacaine plus fentanyl (BF Group) or plain bupivacaine plus mixture of fentanyl and dexmedetomidine (DBF Group). Incidence of hypotension, bradycardia, Apgar scores, intraoperative pain assessment, onset of postoperative pain, sedation scores, and side effects were recorded.Results:No difference in the times taken for block to reach T4 sensory level, to reach the highest level of sensory block, and interval between first neuraxial injection and onset of surgery between the groups was noted. Onset of postoperative pain was significantly delayed in the DBF group (P = 0.001), the need for supplementary fentanyl was significantly less in DBF group (P = 0.03), no significant difference was noted between both groups regarding neonatal Apgar scores as well as the incidence of hypotension, bradycardia, nausea, vomiting, and duration of motor blockade. DBF group had significantly less incidence of shivering (P = 0.03).Conclusion:Adding dexmedetomidine to regular mixture of epidural anesthetics in women undergoing elective cesarean section improved intraoperative conditions and quality of postoperative analgesia without maternal or neonatal significant side effects.

Anaerobe degradation of maize infected by Fusarium graminearum

Last year intense rainfalls and moisture conditions were beneficial for the Fusarium sp. in Hungary. Fusarium strains decrease cereal quality (for example maize), furthermore may cause yield loss. Due to the toxin production, the fungi have a dangerous animal and human pathogen effect (Placinta et al., 1999).The effects of the Fusarium infection and its mycotoxin production haven’t been perfectly eliminated. Fusariumgraminearumis the most common agricultural pathogen in Hungary. The utilization of infected maize as an alternative biogas raw material may be an efficient and environmentally friendly disposal method. In this case, Fusarium-, and mycotoxin-content of the maize have to be analyzed as well as the impact of these factors’ on the biogas production process. Our experience was based on the raw material basis of a biogas plant. Different amount of Fusarium free and infected maize grits have been added to the regular raw material mixture. The detection of Fusarium fungi has been analyzedin experimental digesters throughout the different stages of mesophilic digestion. In the biogas liquid end product the Fusarium was detected by breeding and by microscope. According to our results, the Fusarium sp. was not detectable in the liquid end product after 30 days.

Partitioning two-dimensional mixed phase spaces

Hamiltonian systems typically exhibit a mixture of chaos and regularity, complicating any scheme to partition phase space and extract a symbolic description of the dynamics. In particular, the dynamics in the vicinity of stable islands can exhibit complicated topology that is qualitatively distinct from that away from the islands. We develop an approach to partition the chaotic phase space of a general dynamical system represented by a two-dimensional map (homeomorphism). This approach can accommodate mixed phase space structure with an arbitrarily high degree of accuracy. The partitioning scheme is built around networks of nested heteroclinic tangles—fundamental geometric objects that organize phase–space transport. These tangles can be used to progressively approximate the dynamics in the vicinity of stable island chains. The net result is a symbolic approximation to the dynamics in the chaotic sea, and an associated phase–space partition, which includes the influence of stable islands and which is approximately Markov.

Densities and viscosities of ten binary and ten ternary regular solution systems at 308.15 and 313.15 K

The densities and kinematic viscosities of binary and ternary regular mixtures containing cyclohexane, m-xylene, chlorobenzene, cyclooctane and decane were measured over the entire composition range at 308.15K and 313.15K, respectively. The experimental results were used to test the predictive capability of the six viscosity models available in the literature; namely, the generalized McAllister three-body interaction model, the pseudo-binary McAllister model, the group contribution (GC-UNIMOD) model, the generalized corresponding states principle (GCSP) model, the Allan and Teja correlation and the Grunberg and Nissan law of viscosity. The percentage average absolute deviation (%AAD) was employed as the criterion for comparing the predictive capabilities of the aforementioned models. The experimental pure component data obtained in the present study agreed well with the corresponding literature values at both designated temperatures. The model testing results showed that the generalized McAllister showed the best predictive capability resulting in the lowest %AADs; viz., 3.3 and 3.7 at 308.15K and 313.15K, respectively.

A particle filter driven dynamic Gaussian mixture model approach for complex process monitoring and fault diagnosis

Complex non-Gaussian processes may have dynamic operation scenario shifts so that the conventional monitoring methods become ill-suited. In this article, a new particle filter based dynamic Gaussian mixture model (DGMM) is developed by adopting particle filter re-sampling method to update the mixture model parameters in a dynamic fashion. Then the particle filtered Bayesian inference probability index is established for process fault detection. Furthermore, the particle filtered Bayesian inference contributions are decomposed among different process variables for fault diagnosis. The proposed DGMM monitoring approach is applied to the Tennessee Eastman Chemical process with dynamic mode changes and the results show its superiority to the dynamic principal component analysis (DPCA) and regular Gaussian mixture model (GMM) in terms of fault detection and diagnosis accuracy.

A Double-Clear Variant of Epithelial-Myoepithelial Carcinoma of the Parotid Gland

The hallmark of the histology of epithelial-myoepithelial carcinoma (EMC) is the presence of a regular repetitive mixture of bilayered duct-like structures with an outer layer of myoepithelial cells and inner ductal epithelial cells. Clear cell change in the myoepithelial component is common, but clearing of both cell types, giving an impression of a monocellular neoplasm, is rare. A parotid biopsy was received from an 83-year-old male and subject to routine histologic processing for conventional staining and immunohistochemistry. The encapsulated tumour was composed of sheets of PAS/diastase negative clear cells, separated by fibrous septae. The clear myoepithelial cells were positive for S-100 protein, SMA, and p63 and negative for CK19 and surrounded CK19-positive luminal cells. It is important to utilise immunohistochemistry to differentiate this tumour from others with a similar histologic pattern. Information about the behaviour of the double-clear EMC is limited since there are few cases reported.

A nonlinear kernel Gaussian mixture model based inferential monitoring approach for fault detection and diagnosis of chemical processes

A nonlinear kernel Gaussian mixture model (NKGMM) based inferential monitoring method is proposed in this article for chemical process fault detection and diagnosis. Aimed at the multimode non-Gaussian process with within-mode nonlinearity, the developed NKGMM approach projects the operating data from the raw measurement space into the high-dimensional kernel feature space. Thus the Gaussian mixture model can be estimated in the feature space with each component satisfying multivariate Gaussianity. As a comparison, the conventional independent component analysis (ICA) searches for the non-Gaussian subspace with maximized negentropy, which is not equivalent to the multi-Gaussianity in multimode process. The regular Gaussian mixture model (GMM) method, on the other hand, assumes the Gaussianity of each cluster in the original data space and thus cannot effectively handle the within-mode nonlinearity. With the extracted kernel Gaussian components, the geometric distance driven inferential index is further derived to monitor the process operation and detect the faulty events. Moreover, the kernel Gaussian mixture based inferential index is decomposed into variable contributions for fault diagnosis. For the simulated multimode wastewater treatment process, the proposed NKGMM approach outperforms the ICA and GMM methods in early detection of process faults, minimization of false alarms, and isolation of faulty variables of nonlinear and non-Gaussian multimode processes.

Potassium-bearing clinopyroxene: a review of experimental, crystal chemical and thermodynamic data with petrological applications

AbstractAvailable experimental data on chemical composition and crystal structure of K-bearing clinopyroxenes are compiled together with the results of atomistic simulations and thermodynamic calculations of mineral equilibria. It is shown that the limited solubility of K2O in clinopyroxene from crustal rocks cannot be ascribed to the strong non-ideality of mixing between diopside (CaMgSi2O6) and K-jadeite (KAlSi2O6) components. The more likely reason is the instability of the potassic endmember with respect to other K-bearing phases. As the volume effects of typical K-jadeite-forming reactions are negative, the incorporation of K in the clinopyroxene structure becomes less difficult at higher pressure. Atomistic simulations predict that the thermodynamic mixing properties of diopside-K-jadeite solid-solutions at high temperature approach those of a regular mixture with a relatively small positive excess enthalpy. The standard enthalpy of formation(ΔfH° =—2932.7 kJ/mol), the standard volume(V° =6.479 J mol–1bar–1) and the isothermal bulk modulus(K0=145 GPa) of K-jadeite were calculated from first principles, and the standard entropy(S°= 141.24 J mol–1K–1) and thermal-expansion coefficient (α = 3.3 x 1CP–5K–1) of the K-jadeite endmember were estimated using quasi-harmonic lattice-dynamic calculations based on a force-field model. The estimated thermodynamic data are used to compute compositions of K-bearing clinopyroxenes in diverse mineral assemblages within a wideP-Tinterval. The review substantiates the conclusion that clinopyroxene can serve as an effective container for K at upper-mantle conditions.

Partly-quenched systems containing charges. Structure and dynamics of ions in nanoporous materials

Disordered porous materials filled with liquid or solution may be considered as partly-quenched, i.e., as systems in which some of the degrees of freedom are quenched and others annealed. In such cases, the statistical-mechanical averages used to calculate the system's thermodynamical properties become double ensemble averages: first over the annealed degrees of freedom and then over all possible values of the quenched variables. In this respect, the quenched-annealed systems differ from regular mixtures. The multi-faceted applications of the partly-quenched systems to a kaleidoscope of technological and biological processes make the understanding of these systems important and of interest. Present contribution reviews recent developments in theory and simulation of partly-quenched systems containing charges. Specifically, two different models of such systems are discussed: (a) the model in which the nanoporous system (matrix subsystem) formed by charged obstacles is electroneutral, and (b) the model, where the subsystem of obstacles has some net charge. The latter model resembles, for example, the situation in ion exchange resins etc. Various theoretical methods are applied to investigate structural and dynamical peculiarities of such systems. One is the replica Ornstein-Zernike theory, especially adapted for charged systems, and the other is the Monte Carlo computer simulation method. These two approaches are well suited to study thermodynamical parameters, such as the mean activity coefficient of the annealed electrolyte or Donnan's exclusion parameter. Highly relevant issue of dynamics of ions in partly-quenched systems is also addressed. For this purpose, the Brownian dynamic method is used: the self-diffusion coefficients of ions are calculated for various model parameters and discussed in light of the experimental data. These results, together with the thermodynamical data mentioned above, provide additional evidence that properties of the adsorbed fluid substantially differ from those of its bulk counterpart.

Synergistic effects in mixtures of two identically charged ionic surfactants with different critical micelle concentrations

Expressions for the critical micelle concentration (cmc) and activity coefficients as functions of surfactant composition in mixtures of two identically charged monovalent ionic surfactants are derived from the nonlinear Poisson–Boltzmann (PB) theory. For the special case of no added salt, the simple expression cmcα = xcmcα1 + (1 − x)cmcα2 is deduced, where the exponential parameter α > 1 depends on the number of ionic species in a surfactant molecule as well as the curvature of the self-assembled interface. Theoretical predictions are compared with cmc values obtained with some different experimental techniques for mixtures of the two cationic surfactants didodecyldimethylammonium bromide (DDAB) and dodecyltrimethylammonium bromide (DTAB) in water and in the absence of added salt. It is demonstrated that the PB theory generates significantly better agreement with experimental data than predicted by ideal behaviour or the regular mixture theory. We find that maximum synergistic effects occur at a DDAB mole fraction in solution y = 0.005. According to the PB theory, this very low value of y corresponds to a mole fraction of DDAB in the self-assembled interfacial aggregates equal to x = 0.995. Moreover, our calculations of the surfactant composition in the self-assembled interfacial aggregates above cmc demonstrate that the transition from small micelles to large bilayer aggregates is found to consistently occur at a mole fraction of DDAB equal to about x = 0.41–0.42, irrespective of the surfactant molar ratio in solution. Experimental observations strongly support the fact that concentrations of free surfactant, as well as the surfactant composition in the self-assembled interfacial aggregates, may be accurately calculated from the non-linear Poison–Boltzmann theory. On the other hand, a micelle-to-bilayer transition induced by changes in surfactant mole fraction in the self-assembled interfacial aggregates is consistent with neither ideal surfactant behaviour nor synergistic behaviour according to the regular mixture theory.

Evaluation of the weight‐increasing effects of biphasic analog and regular NPH insulin mixtures in patients with Type 2 diabetes mellitus

Weight gain is a significant problem in diabetic patients in terms of worsening glycemic control, increasing diabetic and cardiovascular morbidity and mortality, and contributing to social and psychological problems. In the present study, we evaluated the effects of a biphasic analog and regular NPH insulin mixtures on weight gain in patients with Type 2 diabetes mellitus (T2DM) over 1 year. Group I consisted of 71 patients (29 men and 42 women) being treated with analog mixtures (insulin lispro 75/25 mix and biphasic insulin aspart 70/30 mix) twice daily; Group II consisted of 69 patients (23 men and 46 women) being treated with a regular insulin mixture (70/30) twice daily. Starting weight, body mass index, HbA1c, and hypoglycemic episodes were evaluated after 6 and 12 months. Weight gain in Group I at 6 and 12 months was 1.41 ± 2.70 and 2.08 ± 3.74 kg, respectively. In Group II, weight gain at 6 and 12 months was 1.5 ± 3.0 and 2.29 ± 3.85 kg, respectively. Intragroup comparisons indicated that, for both groups, weight gain at 6 and 12 months differed significantly from the starting weight. However, no significant differences in weight gain were found between the two groups (P > 0.05). The weight-increasing effects of an analog mixture of insulin and the NPH regular mixture of insulin appear to be similar. This should be taken into account when determining the type of insulin to use in treating T2DM patients.

Detonation propagation with velocity deficits in narrow channels

Propagation limits of detonations in narrow channels have been studied with a focus on velocity deficits and variation in cell widths. A channel was formed by a pair of metal plates of 1500 mm length which were inserted in a detonation tube of 50.5 mm inner diameter. Test gases were hydrogen–oxygen mixtures diluted with argon or nitrogen, which were selected as representatives of regular and irregular mixture systems. The velocity deficits predicted using the concept of negative boundary layer displacement thickness were compared to those obtained experimentally. From good agreement between the predicted and the experimental velocity deficits, the cell width enlarged in the channel was calculated using the induction zone length behind the decelerated leading shock front. Although this calculation underestimates the cell widths, the calculated cell widths were found to be well predicted when they were multiplied by an appropriate proportionality factor. It is found that for given mixtures, a combination of the calculated velocity deficit and the number of cells in a channel contributes to the prediction of propagation limits of detonations.

Monolayers of mixture of alkylaminomethyl rutin and lecithin at the air/water interface

A compound of flavonol-based biosurfactant, as C 8-substituted alkylaminomethyl rutin (DAMR) for a potential pharmaceutical or agrochemical use, was prepared experimentally. The surface behavior of DAMR and its mixture with lecithin from soybean (SL) had been studied. DAMR, regarded as a pseudo-amphoteric character, exhibits both liquid-condensed (LC) and liquid-expanded (LE) phases while SL is in the form of the LE phase only. The phase parameters of DAMR (including A limt, π coll) are observed to strongly depend on both the subphase temperature and the pH, which regulate the degree of ionization. In addition, the observed positive deviation calculated from excess Gibbs free energies of the DAMR–SL system suggests a repulsive interaction between DAMR and SL at all X DAMR values. Also the interaction parameter is found to increase linearly with surface pressure, regardless of composition. Notably, the relationship of logarithmic activity coefficient vs. X DAMR 2 reveals that the molecular interaction of DAMR–SL can be adequately simulated using a simple regular mixture model. Importantly, lower C S - 1 values of this mixture than those with pure DAMR and SL denote weak elasticity of mixed monolayers with values of X DAMR of 0.2–0.8, indicating that the direct addition of DAMR may exert a somewhat adverse influence on SL membranes.

Identification of a Novel l-Serine Analog That Suppresses Osteoclastogenesis in Vitro and Bone Turnover in Vivo

Osteoclasts are multinucleated giant cells with bone resorbing activity. We previously reported that the expression of the transcription factor NFAT2 (NFATc1) induced by receptor activator of NF-kappaB ligand (RANKL) is essential for the formation of multinucleated cells. We subsequently identified L-Ser in the differentiation medium as necessary for the expression of NFAT2. Here we searched for serine analogs that antagonize the function of L-Ser and suppress the formation of osteoclasts in bone marrow as well as RAW264 cells. An analog thus identified, H-Ser(tBu)-OMe x HCl, appeared to suppress the production of 3-ketodihydrosphingosine by serine palmitoyltransferase, and the expression and localization of RANK, a cognate receptor of RANKL, in membrane lipid rafts was down-regulated in the analog-treated cells. The addition of lactosylceramide, however, rescued the osteoclastic formation. When administered in vivo, the analog significantly increased bone density in mice and prevented high bone turnover induced by treatment with soluble RANKL. These results demonstrate a close connection between the metabolism of L-Ser and bone remodeling and also the potential of the analog as a novel therapeutic tool for bone destruction.

A self-organizing learning account of number-form synaesthesia

Some people automatically and involuntarily “see” mental images of numbers in spatial arrays when they think of numbers. This phenomenon, called number forms, shares three key characteristics with the other types of synaesthesia, within-individual consistency, between-individual variety, and mixture of regularity and randomness. A theoretical framework called SOLA (self-organizing learning account of number forms) is proposed, which explains the generation process of number forms and the origin of those three characteristics. The simulations replicated the qualitative properties of the shapes of number forms, the property that numbers are aligned in order of size, that discontinuity usually occurs at the point of carry, and that continuous lines tend to have many bends.

Application of Warm-Mix Modified Asphalt Mixture in Highway Maintenance Project

Warm-mix asphalt (WMA) is a relative new technology that has been used in constructing asphalt pavements around the world. WMA offers many advantages, such as energy-saving, environmental advantage, construction cost reduction, extension of construction season, etc. Current and past researches have indicated satisfactory performance of WMA pavements. Continued application and the desire for improvement of performance of WMA have attracted great interests from pavement communities worldwide. In this research, laboratory and field evaluations were conducted to systematically study the behavior and performance of WMA mixtures modified with styrene-butadiene rubber (SBR) emulsion or epoxy resin. The results showed that the use of epoxy resin resulted in a significant change in the penetration characteristic of WMA, while the addition of styrene-butadiene rubber (SBR) emulsion improved the viscosity and temperature susceptibility of WMA mixtures. No significant changes were observed in WMA ductility. With the same aggregate gradation, SBR-modified WMA mixtures exhibited superior water stability and high-temperature performance to regular WMA mixtures and hot mix asphalt mixtures. Overall, SBR-modified WMA mixtures showed equal or better performances than conventional hot-mix asphalt mixtures did.