Effects of a model for random bottom structure on acoustic intensity in isospeed shallow water are studied. The randomness is due to stochastic variations in the bottom density and sound speed in the horizontal direction beneath a plane water-bottom interface. Ray geometry, spreading loss, and bottom loss and phase shift are examined in order to derive formulas for mean intensity and the varian...

OBJECTIVES The aim of this study was to determine the occurrence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli at an equine clinic and a horseback riding centre, and to discuss the impact of antimicrobial treatment on resistance selection. METHODS Faeces from horses, environmental smears and flies were sampled at both the clinic and riding centre. Staff at the equine clin...

Douglas Theobald recently developed an interesting test putatively capable of quantifying the evidence for a Universal Common Ancestry uniting the three domains of life (Eukarya, Archaea and Bacteria) against hypotheses of Independent Origins for some of these domains. We review here his model, in particular in relation to the treatment of Horizontal Gene Transfer (HGT) and to the quality of se...

Many insect species maintain mutualistic relationships with endosymbiotic bacteria. In contrast to their free-living relatives, horizontal gene transfer (HGT) has traditionally been considered rare in long-term endosymbionts. Nevertheless, meta-omics exploration of certain symbiotic models has unveiled an increasing number of bacteria-bacteria and bacteria-host genetic transfers. The abundance ...

Biological systems are modular, and this modularity affects the evolution of biological systems over time and in different environments. We here develop a theory for the dynamics of evolution in a rugged, modular fitness landscape. We show analytically how horizontal gene transfer couples to the modularity in the system and leads to more rapid rates of evolution at short times. The model, in ge...

Horizontal gene transfer (HGT) is a sensational topic largely because its exploitation to date has been primarily journalistic. Properly packaged it captures the attention of a sensitized lay public and peps up circulation. HGT provides technical challenges for academic scientists as well as market analysts. For fans of science fiction as well as for environmental pessimists, HGT is the stuff o...

One of the main concerns to design earth dam is the stability of the upstream slope of the earth dam in phase of rapid drawdown. Confined pore water pressure reduces the effective stress in this mode, so possibility of the instability and slippage will be increased. The main goal of this research is to investigate changes in the pore water pressure by using horizontal drains in upstream slope o...

The results of an ongoing FEM parametric study are presented regarding the dependence of the resulting piled raft behavior under lateral load and combination of loads on pile diameter, pile length, arrangement of piles and raft thickness. Taguchi method with Analysis of Variance (ANOVA) was employed to calculate the contribution ratio of these factors on the lateral displacement of piled raft. ...

Microbes have recently been recognized as dominant forces in nature, with studies benefiting from gene markers that can be quickly, informatively, and universally surveyed. Viruses, where explored, have proven to be powerful modulators of locally and globally important microbes through mortality, horizontal gene transfer, and metabolic reprogramming. However, community-wide virus studies have b...

An ancient endosymbiosis of an α-proteobacterium produced a diverse range of organelles including mitochondria. Reconstruction of the Pygsuia biforma proteome adds to the mosaic of functional systems present in mitochondrial-related organelles and demonstrates the role of horizontal gene transfer.