Alternative Analytical Expressions for the General van Genuchten-Mualem and van Genuchten-Burdine Hydraulic Conductivity Models

The van Genuchten expressions for the unsaturated soil hydraulic properties, first published in 1980, are used frequently in various vadose zone flow and transport applications assuming a specific relationship between the m and n soil hydraulic parameters. By comparison, probably because of the complexity of the hydraulic conductivity equations, the more general solutions with independent m and n values are rarely used. We expressed the general van Genuchten-Mualem and van Genuchten-Burdine hydraulic conductivity equations in terms of hypergeometric functions, which can be approximated by infinite series that converge rapidly for relatively large values of the van Genuchten-Mualem parameter n but only very slowly when n is close to one. Alternative equations were derived that provide very close approximations of the analytical results. The newly proposed equations allow the use of independent values of the parameters m and n in the soil water retention model of van Genuchten for subsequent prediction of the van Genuchten-Mualem and van Genuchten-Burdine hydraulic conductivity models, thus providing more flexibility in fitting experimental pressure-head-dependent water content, theta(h), and hydraulic conductivity, K(h), or K(theta) data.

Modeling of transpiration reduction in van Genuchten-Mualem type soils

We derive an analytic expression for the matric flux potential (M) for van Genuchten-Mualem (VGM) type soils which can also be written in terms of a converging infinite series. Considering the first four terms of this series, the accuracy of the approximation was verified by comparing it to values of M estimated by numerical finite difference integration. Using values of the parameters for three soils from different texture classes, the proposed four-term approximation showed an almost perfect match with the numerical solution, except for effective saturations higher than 0.9. Including more terms reduced the discrepancy but also increased the complexity of the equation. The four-term equation can be used for most applications. Cases with special interest in nearly saturated soils should include more terms from the infinite series. A transpiration reduction function for use with the VGM equations is derived by combining the derived expression for M with a root water extraction model. The shape of the resulting reduction function and its dependency on the derivative of the soil hydraulic diffusivity D with respect to the soil water content theta is discussed. Positive and negative values of dD/d theta yield concave and convex or S-shaped reduction functions, respectively. On the basis of three data sets, the hydraulic properties of virtually all soils yield concave reduction curves. Such curves based solely on soil hydraulic properties do not account for the complex interactions between shoot growth, root growth, and water availability.

TonB-dependent outer-membrane proteins and siderophore utilization in Pseudomonas fluorescens Pf-5

The soil bacterium Pseudomonas fluorescens Pf-5 produces two siderophores, a pyoverdine and enantio-pyochelin, and its proteome includes 45 TonB-dependent outer-membrane proteins, which commonly function in uptake of siderophores and other substrates from the environment. The 45 proteins share the conserved beta-barrel and plug domains of TonB-dependent proteins but only 18 of them have an N-terminal signaling domain characteristic of TonB-dependent transducers (TBDTs), which participate in cell-surface signaling systems. Phylogenetic analyses of the 18 TBDTs and 27 TonB-dependent receptors (TBDRs), which lack the N-terminal signaling domain, suggest a complex evolutionary history including horizontal transfer among different microbial lineages. Putative functions were assigned to certain TBDRs and TBDTs in clades including well-characterized orthologs from other Pseudomonas spp. A mutant of Pf-5 with deletions in pyoverdine and enantio-pyochelin biosynthesis genes was constructed and characterized for iron-limited growth and utilization of a spectrum of siderophores. The mutant could utilize as iron sources a large number of pyoverdines with diverse structures as well as ferric citrate, heme, and the siderophores ferrichrome, ferrioxamine B, enterobactin, and aerobactin. The diversity and complexity of the TBDTs and TBDRs with roles in iron uptake clearly indicate the importance of iron in the fitness and survival of Pf-5 in the environment.

Biochemistry of the Envenomation Response-a Generator Theme for Interdisciplinary Integration

The understanding of complex physiological processes requires information from many different areas of knowledge. To meet this interdisciplinary scenario, the ability of integrating and articulating information is demanded. The difficulty of such approach arises because, more often than not, information is fragmented through under graduation education in Health Sciences. Shifting from a fragmentary and deep view of many topics to joining them horizontally in a global view is not a trivial task for teachers to implement. To attain that objective we proposed a course herein described Biochemistry of the envenomation response aimed at integrating previous contents of Health Sciences courses, following international recommendations of interdisciplinary model. The contents were organized by modules with increasing topic complexity. The full understanding of the envenoming pathophysiology of each module would be attained by the integration of knowledge from different disciplines. Active-learning strategy was employed focusing concept map drawing. Evaluation was obtained by a 30-item Likert-type survey answered by ninety students; 84% of the students considered that the number of relations that they were able to establish as seen by concept maps increased throughout the course. Similarly, 98% considered that both the theme and the strategy adopted in the course contributed to develop an interdisciplinary view.

Dissociation of deprotonated microcystin variants by collision-induced dissociation following electrospray ionization

Microcystins (MC) are a family of hepatotoxic cyclic heptapeptides produced by a number of different cyanobacterial species. Considering the recent advances in the characterization of deprotonated peptides by mass spectrometry, the fragmentation behavior of four structurally related microcystin compounds was investigated using collision-induced dissociation (CID) experiments on an orbitrap mass spectrometer. It is demonstrated in this study that significant structural information can be obtained from the CID spectra of deprotonated microcystins. A predominant ring-opening reaction at the isoMeAsp residue, as well as two major complementary fragmentation pathways, was observed, reducing the complexity of the product ion spectra in comparison with spectra observed from protonated species. This proposed fragmentation behavior was applied to characterize [Leu(1)]MC-LR from a cyanobacterial cell extract. In conclusion, CID spectra of microcystins in the negative ion mode provide rich structurally informative mass spectra which greatly enhance confidence in structural assignments, in particular when combined with complementary positive ion CID spectra. Copyright (C) 2011 John Wiley & Sons, Ltd.

On compliance of business processes with business contracts

This paper addresses the problem of ensuring compliance of business processes, implemented within and across organisational boundaries, with the constraints stated in related business contracts. In order to deal with the complexity of this problem we propose two solutions that allow for a systematic and increasingly automated support for addressing two specific compliance issues. One solution provides a set of guidelines for progressively transforming contract conditions into business processes that are consistent with contract conditions thus avoiding violation of the rules in contract. Another solution compares rules in business contracts and rules in business processes to check for possible inconsistencies. Both approaches rely on a computer interpretable representation of contract conditions that embodies contract semantics. This semantics is described in terms of a logic based formalism allowing for the description of obligations, prohibitions, permissions and violations conditions in contracts. This semantics was based on an analysis of typical building blocks of many commercial, financial and government contracts. The study proved that our contract formalism provides a good foundation for describing key types of conditions in contracts, and has also given several insights into valuable transformation techniques and formalisms needed to establish better alignment between these two, traditionally separate areas of research and endeavour. The study also revealed a number of new areas of research, some of which we intend to address in near future.

Air Entrainment Processes in a Full-Scale Rectangular Dropshaft at Large Flows

Rectangular dropshafts, commonly used in sewers and storm water systems, are characterised by significant flow aeration. New detailed air-water flow measurements were conducted in a near-full-scale dropshaft at large discharges. In the shaft pool and outflow channel, the results demonstrated the complexity of different competitive air entrainment mechanisms. Bubble size measurements showed a broad range of entrained bubble sizes. Analysis of streamwise distributions of bubbles suggested further some clustering process in the bubbly flow although, in the outflow channel, bubble chords were in average smaller than in the shaft pool. A robust hydrophone was tested to measure bubble acoustic spectra and to assess its field application potential. The acoustic results characterised accurately the order of magnitude of entrained bubble sizes, but the transformation from acoustic frequencies to bubble radii did not predict correctly the probability distribution functions of bubble sizes.

Central Cardiovascular Anatomy and Function in Crocodilia

Abstract: Among the vertebrates, crocodilians have the most complex anatomy of the heart and outflow channels. Their cardiovascular anatomy may also be the most func­tionally sophisticated, combining as it does the best features of both reptilian and mammalian (and avian) systems. The puzzlingly complex "plumbing" of crocodilians has fascinated ana­tomists and physiologists for a very long time, the first paper being that by Panizza (1833). Gradually, with the application of successive techniques of investigation as they became available, its functional significance has become reasonably clear, and the complexity is now revealed as a cardiovascular system of considerable elegance. In this paper I will review the main anatomical features of the heart and outflow channels, discuss what is known about the way they work, and speculate about the probable functional significance.

Thomas Parmeter: Poetaster and Rhymist

The life of Dr. Thomas Parmeter MD was one of astonishing complexity. Convicted of bigamy in London, he arrived in Sydney on 16 January 1816 and almost immediately resumed his medical practice. In England he had engaged in several literary activities and these too he soon resumed in New South Wales, contributing to contemporary newspapers. A riding accident in 1820 and a stroke in 1825 restricted his ability to practise medicine and so he turned to writing and farming for an income. Neither activity was a financial success and he died in poverty. Herein are collected together his poems, epigrams, aphorisms and quotations from poets and other writers. His contribution to the cultural life of Sydney, though not fully documented, was very likely significant.

One size doesn't fit all: Research methodologies in a language variation study of Sudanese teens

The research reported here draws on a study of five teenagers from a Dinka-speaking community of Sudanese settling in Australia. A range of factors including language proficiency, social network structure and language attitudes are examined as possible causes for the variability of language use. The results and discussion illustrate how the use of a triangular research approach captured the complexity of the participants' language situation and was critical to developing a full understanding of the interplay of factors influencing the teens' language maintenance and shift in a way that no single method could. Further, it shows that employment of different methodologies allowed for flexibility in data collection to ensure the fullest response from participants. Overall, this research suggests that for studies of non-standard communities, variability in research methods may prove more of a strength that the use of standardised instruments and approaches.

Mummy! Ball! Fish!: Why English-learning children produce nouns earlier than verbs

When English-learning children begin using words the majority of their early utterances (around 80%) are nouns. Compared to nouns, there is a paucity of verbs or non-verb relational words, such as 'up' meaning 'pick me up'. The primary explanations to account for these differences in use either argue in support of a 'cognitive account', which claims that verbs entail more cognitive complexity than nouns, or they provide evidence challenging this account. In this paper I propose an additional explanation for children's noun/verb asymmetry. Presenting a 'multi-modal account' of word-learning based on children's gesture and word combinations, I show that at the one-word stage English-learning children use gestures to express verb-like elements which leaves their words free to express noun-like elements.

BIO Logical Agents: Norms, Beliefs, Intentions in Defeasible Logic

In this paper we follow the BOID (Belief, Obligation, Intention, Desire) architecture to describe agents and agent types in Defeasible Logic. We argue, in particular, that the introduction of obligations can provide a new reading of the concepts of intention and intentionality. Then we examine the notion of social agent (i.e., an agent where obligations prevail over intentions) and discuss some computational and philosophical issues related to it. We show that the notion of social agent either requires more complex computations or has some philosophical drawbacks.

Wolbachia: Invasion biology in South Pacific butterflies

Wolbachia ensdosymbionts are well known for their ability to manipulate the population biology and development of their hosts. One of the less studied outcomes of Wolbachia infection with this symbiont is the selective killing of male embryos. Recent work on butterflies living on different South Pacific islands is beginning to help us understand the complexity of the co-evolutionary interactions between these partners.

Sampling phylogenetic tree space with the generalized Gibbs sampler

The generalized Gibbs sampler (GGS) is a recently developed Markov chain Monte Carlo (MCMC) technique that enables Gibbs-like sampling of state spaces that lack a convenient representation in terms of a fixed coordinate system. This paper describes a new sampler, called the tree sampler, which uses the GGS to sample from a state space consisting of phylogenetic trees. The tree sampler is useful for a wide range of phylogenetic applications, including Bayesian, maximum likelihood, and maximum parsimony methods. A fast new algorithm to search for a maximum parsimony phylogeny is presented, using the tree sampler in the context of simulated annealing. The mathematics underlying the algorithm is explained and its time complexity is analyzed. The method is tested on two large data sets consisting of 123 sequences and 500 sequences, respectively. The new algorithm is shown to compare very favorably in terms of speed and accuracy to the program DNAPARS from the PHYLIP package.

Multicomponent reversible reactions inside a porous catalyst pellet

This work deals with a solution method to handle multicomponents reversible reactions occurring inside a porous catalyst pellet. The complexity of this problem arises from the fact that the effective diffusivities and Biot number, which characterizes the external mass transfer, are different for each chemical species. In mathematical terms, this means that each chemical species has its own subspace and, therefore, when the technique of finite integral transform is applied to solve this multicomponent problem, each chemical species is associated with its own integral transform kernel. The analytical solutions obtained for this problem are compact and simple for any further manipulation. Application of this result to the catalytic reforming of C7 hydrocarbon system is shown in this paper.