Do native predators feed on non-native prey? The case of round goby in a fluvial piscivorous fish assemblage

We evaluated whether or not the invasive round goby (Neogobius melanostomus) represents an important prey source for seven native fish predators in Lake St. Pierre (St. Lawrence River, Canada). The frequency of occurrence of round goby in the stomach contents of brown bullhead (Ameiurus nebulosus) and channel catfish (Ictalurus punctatus) was very low (< 5%), while for the five other predators, it varied between 22% (yellow perch; Perca flavescens) and 65% (sauger; Sander canadensis). Several competing models linking the probability of occurrence of round goby in stomach contents to variables related to space, physical habitat, biotic interactions and predator size were tested for the five species feeding on round goby. Results indicated that space variables influenced round goby occurrence in stomachs for all species. In addition, physical habitat variables had an influence for sauger and walleye (Sander vitreus); biotic variables had an influence for yellow perch, walleye and sauger; and size had an influence for northern pike (Esox lucius), smallmouth bass (Micropterus dolomieu) and walleye. These results are discussed in light of known biological features of the round goby and native predators studied here and have important implications in terms of understanding round goby invasion success in the Great Lakes–St. Lawrence system.     

DIVCLUS-T: A monothetic divisive hierarchical clustering method

DIVCLUS-T is a divisive hierarchical clustering algorithm based on a monothetic bipartitional approach allowing the dendrogram of the hierarchy to be read as a decision tree. It is designed for either numerical or categorical data. Like the Ward agglomerative hierarchical clustering algorithm and the k-means partitioning algorithm, it is based on the minimization of the inertia criterion. However, unlike Ward and k-means, it provides a simple and natural interpretation of the clusters. The price paid by construction in terms of inertia by DIVCLUS-T for this additional interpretation is studied by applying the three algorithms on six databases from the UCI Machine Learning repository.     

Scattering on a ring of processors

In this note, we prove that the complexity of scattering in an oriented ring of p processors is (p - 1) (β + Lτ) where L is the length of the messages, β the communication startup, and τ the elemental propagation time.     

A method of generating translations of unseen n‐grams by using proportional analogy

In recent years, statistical machine translation has gained much attention. The phrase‐based statistical machine translation model has made significant advancement in translation quality over the word‐based model. In this paper, we attempt to apply the technique of proportional analogy to statistical machine translation systems. We propose a novel approach to apply proportional analogy to generate translations of unseen n‐grams from the phrase table for phrase‐based statistical machine translation. Experiments are conducted with two datasets of different sizes. We also investigate two methods to integrate n‐grams translations produced by proportional analogy into the state‐of‐the‐art statistical machine translation system, Moses.¹ The experimental results show that unseen n‐grams translations generated using the technique of proportional analogy are rewarding for statistical machine translation systems with small datasets. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Peculiar crystallization kinetics of biodegradable poly(lactic acid)/poly(propylene carbonate) blends

Binary blends of poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) were found to display a peculiar crystallization kinetics. The two biodegradable polymers were blended by melt mixing, to obtain binary blends at various compositions. Temperature‐modulated calorimetry and dynamic‐mechanical analysis indicated that the blend components are partially miscible, and display two separate glass transitions, at temperatures intermediate to those of the plain polymers. Electron microscopy analysis disclosed the morphology of PLA/PPC blends, made of PPC‐rich particles finely dispersed within the PLA‐rich matrix. The possible establishment of interactions between the functional groups of the two polymers upon melt mixing has been hypothesized as the reason for partial miscibility and compatibility of the two biodegradable polymers. The PLA/PPC blends display good mechanical properties, with enhanced performance at rupture compared with plain PLA. Most importantly, the addition of PPC affects also the crystallization kinetics of PLA, since the more mobile PPC chains favor diffusion of the stiffer PLA chain segments towards the growing crystals, which fastens the spherulite growth rate of PLA. Such positive influence of an amorphous polymer on crystal growth rate has been demonstrated here for the first time in blends that display phase‐separation in the melt. POLYM. ENG. SCI., 55:2698–2705, 2015. © 2015 Society of Plastics Engineers     

Relationship between structure and rheological,mechanical and thermal properties of polylactide/Cloisite 30B nanocomposites

Melt‐state and solid state mechanical properties and thermal stability of polylactide layered silicate nanocomposites elaborated by melt intercalation were studied as a function of clay content. Wide angle X‐ray scattering results, transmission electron microscopy observations, and rheological measurements indicated that the clay was finely distributed in the polylactide matrix. Contrary to nonlinear mechanical properties, thermal and linear mechanical properties were shown to increase with increasing clay fraction. The nanoindentation measurements confirm the significant increase of linear mechanical properties previously observed by tensile tests. The good correlation of linear mechanical properties at the macrometric and nanometric scales is explained by the high dispersion degree of the nanofiller in the biodegradable polymer matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Microrheology: new methods to approach the functional properties of food

Three configurations have been developed to improve the understanding of structural element interactions in food material during deformation. The three configurations combine an inverted confocal scanning laser microscope (CSLM) and a cell that can apply to the sample a specific deformation: continuous shear, linear oscillatory shear and biaxial extension (compression).In the continuous shear and oscillatory shear configurations (OSCs), a zero-velocity plane is created in the sample by moving two plates in opposite direction, maintaining stable observation conditions of the structural behaviour under deformation. The OSC allows simultaneous application of CSLM and diffusing wave spectroscopy, a multiple light scattering technique. The third configuration (compression configuration) allows observation at a stagnation point during rheometric measurements. The configurations accept semi-liquid products (dressing, sauces, dairy products, etc.) for investigations in area such as aggregation, gelation, interactions at interface, coalescence, break-up.     

Tracking maximum efficiency of hydrogen genset used as electric vehicle range extender

This paper investigates a hydrogen-based genset maximum efficiency tracking problem in the context of electric vehicle range extension. This genset is cheaper than fuel cells and has the desirable property of being greenhouse gas emission free in addition to being less pollutant than the conventional gasoline based gensets. Using Taylor's series, a parametric efficiency model is built iteratively. This model is used by a nonlinear optimization method which searches for the optimal operating conditions for a maximum achievable efficiency. The root-mean-square-error between experimental data and the model is less than 5 × 10⁻⁴. The hardware-in-the-loop simulation demonstrated that the proposed tracking approach is effective. In addition, it can improve the hydrogen-based genset efficiency up to 7.15% compared to the commonly used industrial method based on a constant speed drive approach.