Adipose-derived stem cells could sense the nano-scale cues as myogenic-differentiating factors

Microenvironmental cues, such as surface topography and substrate stiffness, may affect stem cells adhesion, morphology, alignment, proliferation and differentiation. Adipose derived stem cells (ASCs) have attracted considerable interest in regenerative medicine due to their easy isolation, extensive in vitro expandability and ability to differentiate along a number of different tissue-specific lineages. The aim of this work was to investigate ASCs adhesion, alignment and differentiation into myogenic lineage on nanofibrous polymeric scaffolds with anisotropic topography. Nanostructured scaffolds with randomized or parallel fibers were fabricated by electrospinning using polycaprolactone (PCL) and the polycarbonate-urethane ChronoFlex AL 80A (CFAL). Cells expressed myosin (fast skeletal) and tropomyosin in all surface topographies 7 days after seeding but myotube formation was only observed on CFAL scaffolds and only few myotubes were formed on PCL scaffolds. The different cell behavior could be ascribed to two main parameters: fibers dimensions and fibers orientation of the substrates that could result in a better myotube formation on CFAL scaffolds.     

Dispersion equilibria in spatial Cournot competition

We consider the standard model of spatial Cournot competition and show that for dispersion equilibria to exist, (a) a necessary condition is that the distribution be not unimodal, and (b) a sufficient condition is that the distribution be convex with a unique antimode and that asymmetry is not too strong.     

Effect of Myosin Isoforms on Cardiac Muscle Twitch of Mice,Rats and Humans

To understand how pathology-induced changes in contractile protein isoforms modulate cardiac muscle function, it is necessary to quantify the temporal-mechanical properties of contractions that occur under various conditions. Pathological responses are much easier to study in animal model systems than in humans, but extrapolation between species presents numerous challenges. Employing computational approaches can help elucidate relationships that are difficult to test experimentally by translating the observations from rats and mice, as model organisms, to the human heart. Here, we use the spatially explicit MUSICO platform to model twitch contractions from rodent and human trabeculae collected in a single laboratory. This approach allowed us to identify the variations in kinetic characteristics of α- and β-myosin isoforms across species and to quantify their effect on cardiac muscle contractile responses. The simulations showed how the twitch transient varied with the ratio of the two myosin isoforms. Particularly, the rate of tension rise was proportional to the fraction of α-myosin present, while the β-isoform dominated the rate of relaxation unless α-myosin was >50%. Moreover, both the myosin isoform and the Ca²⁺ transient contributed to the twitch tension transient, allowing two levels of regulation of twitch contraction.     

Habitat Suitability and Landscape Structure: A Maximum Entropy Approach in a Mediterranean Area

Species distribution models have recently become important tools in ecological research. Prediction of suitable habitats for threatened and endangered species is essential for the conservation and management of their native habitats. A landscape scale approach is relevant for biodiversity conservation since landscape planning and management are generally conducted at wide spatial scales, focusing on areas with complex landscape configuration as a consequence of human activities. The aims of this study were to test a maximum entropy approach (Maxent) to the development of a niche-based model for species of conservation interest and to relate this model to landscape structure metrics. The results obtained here showed a good predictive power of Maxent for the three target species and highlighted the importance of landscape structure analysis for the detection of patterns of habitat suitability. Moreover, this work stressed that combining classical environmental information with landscape structure in analysing habitat suitability for species of conservation interest may be used to guide conservation efforts and landscape management practices.     

External Shape Differences between Sympatric Populations of Commercial Clams <Emphasis Type="Italic">Tapes decussatus</Emphasis> and <Emphasis Type="Italic">T. philippinarum</Emphasis>

The actual Italian production of clams is chiefly sustained by the native Tapes decussatus and the fortuitously imported Tapes philippinarum. Both species are commercialized as “Vongola verace”, but the commercial value of T. philippinarum is lower. The discrimination of species by sight is usually difficult and it cannot be done by observation based on shell morphology but only when animals open their valves hence displaying the two siphons. In this study, we propose a new, noninvasive method to discriminate individuals of both species based on the analysis of the external shape of their shells. Accordingly, in sympatric populations at two sites of the Po river outlet, we have chosen individuals (63 for T. decussatus and 57 for T. philippinarum) of comparable commercial size for which a certain genetic discrimination was previously done. Pictures of the left side valve were taken for all specimens. Their profiles were analyzed with the elliptic Fourier analysis. The mean outline for each species was graphically extracted. The coefficients of the harmonic equations were analyzed by multivariate classification (partial least squares discriminant analysis [PLSDA]). Results showed a high percentage of correct classification of individuals of both species (96.6%). Contour analysis reflected the overall shell shape and thus identified morphological aspects that were difficult to recognize and quantify in sight. The high percentage of correct classifications obtained by combining the analysis of elliptic Fourier harmonics with PLSDA demonstrated the feasibility of this method to discriminate species with a high level of resemblance.     

A3M: an agent architecture for automated manufacturing

This paper proposes a software architecture based on mobile agents for distributed process control applications. A set of agents is employed to handle, in a single manufacturing cell, automatic assignment of control tasks to controllers, monitoring of cell functionalities and dynamic cell reconfiguration. The agents operate in a two‐layered structure: at the highest level, the planning agents analyse the inputs of the system designer and automatically create the field agents, which operate at the lowest level and embed the control tasks to be executed. Field agents, which are mobile, are able to reach autonomously the controllers of the cell, in order to perform the control activity there. Exploiting the mobility enables a field agent to change its running device when the variation of the design parameters or a system fault requires a new task distribution. A load‐balancing algorithm is introduced, with the objective of assigning each field agent to a controller of the manufacturing cell in order to fairly distribute the computation load. The algorithm uses a branch‐and‐bound technique to explore all possible solutions and applies two heuristics to throw away non‐feasible solutions and select the best branch to analyse. The algorithm is designed to run on‐line in order to allow a fast task redistribution when a fault condition occurs in the process control environment. Copyright © 2008 John Wiley & Sons, Ltd.