Boundary Spatiotemporal Correlations in a Self-Organized Critical Model of Punctuated Equilibrium

In a semi-infinite geometry, a 1D, M-component model of biological evolution realizes microscopically an inhomogeneous branching process for $M \to \infty$. This implies in particular a size distribution exponent $\tau'=7/4$ for avalanches starting at a free end of the evolutionary chain. A bulk--like behavior with $\tau'=3/2$ is restored if `conservative' boundary conditions strictly fix to its critical, bulk value the average number of species directly involved in an evolutionary avalanche by the mutating species located at the chain end. A two-site correlation function exponent ${\tau_R}'=4$ is also calculated exactly in the `dissipative' case, when one of the points is at the border. These results, together with accurate numerical determinations of the time recurrence exponent $\tau_{first}'$, show also that, no matter whether dissipation is present or not, boundary avalanches have the same space and time fractal dimensions as in the bulk, and their distribution exponents obey the basic scaling laws holding there.Comment: 5 pages, 3 eps figure

Diets of shags Phalacrocorax aristotelis and cormorants P. carbo in Norway and possible implications for gadoid stock recruitment

The diets of shags and cormorants were studied in Norway through analyses of regurgitated pellets. Although this method has many limitations, indications were that both species rely heavily on small gadoids (Gadidae) and sand eels (Ammodytidae) for food throughout their range, but also eat other fish species when available. There was considerable dietary overlap between species, despite a tendency for cormorants to eat larger fish and more benthic items than shags. Predation by shags and cormorants could be a factor limiting the recruitment of cod and saithe into what are now severely reduced, but commercially important stocks in the Norwegian and Barents Seas

Empedocle e Freud: riflessioni su logica e linguaggio

The present piece, first presented on 19 November 2016 at the Centre Léon Robin (CNRS-Univ. Paris-Sorbonne-ENS Ulm) as part of the“Présocratiques” Seminar, is an investigation of the relationship between Empedocles and Freud. The analysis is divided into three parts: the first section examines the nature of Freud’s engagement with Empedocles; next, consideration is given to the similarities between their doctrines, based on the extant fragments of the Empedoclean corpus; finally, I offer a series of observations about Empedocles’ poetic style, which shares strong affinities with the spoken word in a manner typical of the oral tradition and is freighted with corporeal and emotional significance. It is here that we see the emergence of one of the key concepts of psychoanalysis: the relationship between logos and alogon, between that which can be rationally analysed and that which can be intuited but which eludes the domain of logos

Micromixing and microchannel design: Vortex shape and entropy

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.In very recent years microdevices, due to their potency in replacing large-scale conventional laboratory instrumentation, are becoming a fast and low cost technology for the treatment of several chemical and biological processes. In particular microfluidics has been massively investigated, aiming at improving the performance of chemical reactors. This is because of the fact that reaction is often an interface phenomenon where the greater the surface to volume ratio, the higher the reaction speed, and microscale mixing increases the interfacial area (in terms of mixing-induced-by-vortices generation). However, microfluidic systems suffer from the limitation that they are characterized mostly by very low Reynolds numbers, with the consequence that (i) they cannot take advantage from the turbulence mixing support, and (ii) viscosity hampers proper vortex detection. Therefore, the proper design of micro-channels (MCs) becomes essential. In this framework, several geometries have been proposed to induce mixing vortices in MCs. However a quantitative comparison between proposed geometries in terms of their passive mixing potency can be done only after proper definition of vortex formation (topology, size) and mixing performance. The objective of this study is to test the ability of different fluid dynamic metrics in vortex detection and mixing effectiveness in micromixers. This is done numerically solving different conditions for the flow in a classic passive mixer, a ring shaped MC. We speculate that MCs design could take advantage from fluidic metrics able to rank properly flow related mixing

Preparation and Characterization of Simvastatin Loaded PLGA Microparticles forTissue Engineering Applications

Simvastatin has been reported to promote osteoblastic activity and inhibit osteoclastic activity. The successful use of simvastatin to promote in vivo bone formation depends on the local concentration, and there have been continuous efforts to find an appropriate delivery system for local delivery. Controlled drug delivery approaches based on microparticles could be a promising approach for sustained-localized delivery of simvastatin. In this study, simvastatin-loaded PLGA microparticles were prepared by using a modified single emulsion-solvent evaporation method. Uniform, spherical simvastatin loaded PLGA microparticles of size below 10μm were produced by adopting three different drug polymer ratios such as 1:40, 1:20 and 1:10 with encapsulation efficiency above 85%w/w irrespective to the drug polymer ratio and maximum simvastatin loading within PLGA microparticles was observed at drug polymer ratio of 1:10. Two stage release of simvastatin from microparticles was observed for 45 days, illustrating a controlled release. Simvastatin loaded PLGA microparticles are compatible with hFOB cells and induced in vitro bio-mineralization during 11 days treatment. These studies illustrate the feasibility of achieving local delivery of simvastatin to induce in vivo bone formation activity by suitably engrafting simvastatin loaded microparticles within porous scaffolds

The temporalis muscle flap for reconstruction of soft palate and lateral oropharyngeal wall after transoral robotic surgery

Trans Oral Robotic Surgery (TORS) is a prominent surgical approach for the resection of oropharyngeal tumors without division of the lip and mandible. Some defects following TORS are large and complex enough to benefit soft-tissue coverage. The pedicled temporalis muscle flap is a versatile and reliable flap and may be a valid option to reconstruct defects of the lateral pharyngeal wall and partial soft palate