Metric characterization of cluster dynamics on the Sierpinski gasket

We develop and implement an algorithm for the quantitative characterization of cluster dynamics occurring on cellular automata defined on an arbitrary structure. As a prototype for such systems we focus on the Ising model on a finite Sierpsinski Gasket, which is known to possess a complex thermodynamic behavior. Our algorithm requires the projection of evolving configurations into an appropriate partition space, where an information-based metrics (Rohlin distance) can be naturally defined and worked out in order to detect the changing and the stable components of clusters. The analysis highlights the existence of different temperature regimes according to the size and the rate of change of clusters. Such regimes are, in turn, related to the correlation length and the emerging "critical" fluctuations, in agreement with previous thermodynamic analysis, hence providing a non-trivial geometric description of the peculiar critical-like behavior exhibited by the system. Moreover, at high temperatures, we highlight the existence of different time scales controlling the evolution towards chaos.Comment: 20 pages, 8 figure

Metric Features of a Dipolar Model

The lattice spin model, with nearest neighbor ferromagnetic exchange and long range dipolar interaction, is studied by the method of time series for observables based on cluster configurations and associated partitions, such as Shannon entropy, Hamming and Rohlin distances. Previous results based on the two peaks shape of the specific heat, suggested the existence of two possible transitions. By the analysis of the Shannon entropy we are able to prove that the first one is a true phase transition corresponding to a particular melting process of oriented domains, where colored noise is present almost independently of true fractality. The second one is not a real transition and it may be ascribed to a smooth balancing between two geometrical effects: a progressive fragmentation of the big clusters (possibly creating fractals), and the slow onset of a small clusters chaotic phase. Comparison with the nearest neighbor Ising ferromagnetic system points out a substantial difference in the cluster geometrical properties of the two models and in their critical behavior.Comment: 20 pages, 15 figures, submitted to JPhys

Microscopic energy flows in disordered Ising spin systems

An efficient microcanonical dynamics has been recently introduced for Ising spin models embedded in a generic connected graph even in the presence of disorder i.e. with the spin couplings chosen from a random distribution. Such a dynamics allows a coherent definition of local temperatures also when open boundaries are coupled to thermostats, imposing an energy flow. Within this framework, here we introduce a consistent definition for local energy currents and we study their dependence on the disorder. In the linear response regime, when the global gradient between thermostats is small, we also define local conductivities following a Fourier dicretized picture. Then, we work out a linearized "mean-field approximation", where local conductivities are supposed to depend on local couplings and temperatures only. We compare the approximated currents with the exact results of the nonlinear system, showing the reliability range of the mean-field approach, which proves very good at high temperatures and not so efficient in the critical region. In the numerical studies we focus on the disordered cylinder but our results could be extended to an arbitrary, disordered spin model on a generic discrete structures.Comment: 12 pages, 6 figure

The larval midgut of Hermetia illucens is characterized by a highly complex structural organization

The demand for food of animal origin is expected to increase by 70-80% within 2050, with a consequent rise in feed requirement. Another serious concern is represented by food waste disposal: in fact, it is estimated that 1.3 billion tons/year of food are globally wasted. The dipteran Hermetia illucens, also known as black soldier fly (BSF), is a promising insect species to tackle these critical challenges because of the ability of the larvae to grow on different organic substrates and their efficiency in the bioconversion process. Moreover, the high nutritional value of the larvae and pupae makes them an alternative protein source for the production of fish feed. A deep understanding of the biology of the larval midgut, which is implicated in food digestion and nutrient absorption, is essential to better comprehend the extraordinary dietary plasticity of the larva. In the present study, we performed a morphological characterization of the midgut of last instar larvae. Our results demonstrate that the larval midgut is composed of three distinct anatomical regions with different luminal pH. These regions are characterized by different cell types that accomplish digestion and absorption activities (columnar cells), acidification of the midgut lumen (cuprophilic cells), regulation processes (endocrine cells), and growth of the epithelium (stem cells). Moreover, we are investigating the expression of different enzymes along BSF midgut epithelium, which are involved in transport mechanisms. This work was supported by Fondazione Cariplo (Insect bioconversion: from vegetable waste to protein production for fish feed, ID 2014-0550)

Molecular and functional characterization of Hermetia illucens larval midgut

The increase in global demand for meat and the management of organic waste are huge global issues. In addition to policies to contain the excessive meat consumption and the production of food waste, a possible perspective is to consider insects as agents for organic waste reduction and as source of protein for monogastric feed production. The larvae of Hermetia illucens (Diptera: Stratiomyidae) are good candidates for bioconversion of vegetal waste and feed production because they grow on different organic substrates and the dry-matter of the prepupa contains a very high percentage of protein with high nutritional value. The study of H. illucens midgut physiology is essential to understand the extraordinary feeding plasticity of this insect and to best exploit this ability. We characterized the digestive enzymes involved in the initial phase of digestion in the three regions of the midgut (anterior, middle and posterior). The proteolytic activity was assayed using chromogenic substrates and specific inhibitors. The total proteolytic activity is highest in the posterior midgut and the major activity is due to serine proteases. We measured the activity and the transcript levels of the two main serine proteases involved in insect digestion: trypsin-like and chymotrypsin-like proteases. Moreover, we determined the total amylolytic activity and the highest value was recorded in the anterior midgut. Thanks to our data, we propose the first model of the functional activity of H. illucens midgut. This work was supported by Fondazione Cariplo (Insect bioconversion: from vegetable waste to protein production for fish feed, ID 2014-0550)

Insights Into the Immune Response of the Black Soldier Fly Larvae to Bacteria

In insects, a complex and effective immune system that can be rapidly activated by a plethora of stimuli has evolved. Although the main cellular and humoral mechanisms and their activation pathways are highly conserved across insects, the timing and the ef\ufb01cacy of triggered immune responses can differ among different species. In this scenario, an insect deserving particular attention is the black soldier \ufb02 y (BSF), Hermetia illucens (Diptera: Stratiomyidae). Indeed, BSF larvae can be reared on a wide range of decaying organic substrates and, thanks to their high protein and lipid content, they represent a valuable source of macromolecules useful for different applications (e.g., production of feedstuff, bioplastics, and biodiesel), thus contributing to the development of circular economy supply chains for waste valorization. However, decaying substrates bring the larvae into contact with different potential pathogens that can challenge their health status and growth. Although these life strategies have presumably contributed to shape the evolution of a sophisticated and ef \ufb01 cient immune system in this dipteran, knowledge about its functional features is still fragmentary. In the present study, we investigated the processes underpinning the immune response to bacteria in H. illucens larvae and characterized their reaction times. Our data demonstrate that the cellular and humoral responses in this insect show different kinetics: phagocytosis and encapsulation are rapidly triggered after the immune challenge, while the humoral components intervene later. Moreover, although both Gram-positive and Gram-negative bacteria are completely removed from the insect body within a few hours after injection, Gram-positive bacteria persist in the hemolymph longer than do Gram-negative bacteria. Finally, the activity of two key actors of the humoral response, i.e., lysozyme and phenoloxidase, show unusual dynamics as compared to other insects. This study represents the \ufb01 rst detailed characterization of the immune response to bacteria of H. illucens larvae, expanding knowledge on the defense mechanisms of this insect among Diptera. This information is a prerequisite to manipulating the larval immune response by nutritional and environmental factors to increase resistance to pathogens and optimize health status during mass rearing

Demonstration of the metaphylactic use of gamithromycin against bacterial pathogens associated with bovine respiratory disease in a multicentre farm trial

On five commercial cattle rearing sites across Europe, a total of 802 young cattle at high risk of developing bovine respiratory disease (BRD) associated with the bacterial pathogens Mannheimia haemolytica or Pasteurella multocida and/or Mycoplasma bovis were enrolled into a multicentre, controlled field trial. Half were treated with a single dose of gamithromycin at 6 mg/kg bodyweight by subcutaneous injection and half received an injection of a saline placebo as the control. All animals were observed daily for 14 days for signs of BRD as defined by set criteria. The proportion of metaphylactic preventive treatment successes, defined as animals surviving to day 14 without signs of BRD, in the gamithromycin-treated group (86 per cent) was significantly (P=0.0012) higher than in the saline-treated controls (61 per cent). Morbidity among the treated animals was reduced by 64 per cent compared with the controls

Polypeptides from Hermetia illucens: a bio source for innovative materials in the framework of a circular economy model

Plastic waste reduction is one of the main challenges of the 21st century from an environmental and sustainability perspective. Still nowadays, relatively little plastic waste is collected for recycling (less than 10%) and a large fraction (approximately 20%) of Municipal Solid Waste (MSW) goes to landfill. At the global level, the generation of municipal solid waste (MSW) is estimated to be 2.5 billion tonnes per year, of which 30-55% is represented by the so-called organic fraction of municipal solid waste (OFMSW). While the use of alternative, plastic-like materials from natural sources could be one of the most appealing solutions, the massive occupation of agricultural soils for their supply is a big concern. In this scenario, waste valorization is gaining major relevance within the framework of circular economy models, with bio-conversion mediated from insects being one possible and effective answer. The project RICH (Turning Rubbish Into biobased materials: a sustainable CHain for the full valorization of organic waste) aims to develop an innovative and integrated circular economy chain, which, starting from the biotransformation of the organic fraction of municipal solid waste (OFMSW), allows the targeted production of biobased materials with high technological value, such as bioplastics and other advanced protein-based materials. In the present study, proteins and polypeptides were extracted from larvae of Hermetia illucens, also known as black soldier fly. Extracts were characterized by means of proteomics techniques such as BCA, SDSPAGE, and LC-MS analyses. Procedures were next defined to prepare materials such as films, tuning the mechanical properties, and investigating the correlation with the molecular structure. Elastic films were obtained and the elasticity was correlated with the chemical composition and the protocol for film preparation. The results so far obtained pave the way for the application of these materials in the biomedical and packaging fields, bringing us closer to the completion of a new circular economy model

Innovative bioplastics from polypeptides of Hermetia illucens

The environmentally sustainable waste management, together with waste valorization, is one of the actual challenges pursued by the European Commission. UE policies are thus contributing in the frameworks of circular economy by promoting the extraction of high quality materials from wastes. At the European level, the generation of municipal solid waste (MSW) is estimated to be 500 kg per capita, of which 70% (discarded food, yard trimmings, paper and wood) is represented by the so-called organic fraction of municipal solid waste (OFMSW). In this scenario, organic waste valorization is gaining major relevance within circular economy models, with bioconversion mediated from insects being one possible and effective answer to the problem. The project RICH (Turning Rubbish Into biobased materials: a sustainable CHain for the full valorization of organic waste) aims to develop an innovative and integrated circular economy chain, which, starting from the biotransformation of the organic fraction of municipal solid waste (OFMSW), allows the targeted production of biobased materials with high technological value, such as bioplastics and other advanced protein-based materials. In the present study, proteins and polypeptides were extracted from larvae and pupae of Hermetia illucens, also known as Black Soldier Fly. The extraction efficiency from both stages was assessed. Crude extracts were characterized by means of proteomics techniques such as BCA, SDS-PAGE, and LC-MS analyses. State of art materials were prepared, investigating the correlation with the molecular structure through physical techniques (FTIR, Contact Angle, TGA). Results clearly points out a correlation between film-forming ability and the chosen larval stage, with extracts from Larvae at the 6th instar leading to the best results. A correlation with polypeptide chain length is proposed