Emergence of Leadership in a Group of Autonomous Robots

For modern biology and ethology, the reason for the emergence of leaders-followers patterns in groups of living organisms, is the need of social coordination. In this paper we attempt to examine factors contributing to the emergence of leadership, trying to understand the relation between leader role and behavioral capabilities. In order to achieve this goal, we use a simulation technique where a group of foraging robots has to choose between two identical food zones. Thus, robots must coordinate in some way in order to select the same food zone and collectively gathering food. Behavioral and quantitative analysis indicate that a form of leadership emerges and the emergence of leadership relates with high level of fitness. Moreover, we show that more skilled individuals in a group tend to assume a leadership role, in agreement with literature

Novel PBAT‐Based Biocomposites Reinforced with Bioresorbable Phosphate Glass Microparticles

Biocomposites based on poly(butylene adipate terephthalate) (PBAT) and reinforced with micro-particles of inorganic biodegradable phosphate glass (PG) at 2, 10, and 40 wt% are prepared and characterized from a mechanical and morphological point of view. Scanning electron microscope (SEM) images show a good dispersion of the PG micro-grains, even at high concentrations, in the PBAT matrix, resulting in homogeneous composites. Tensile and dynamic-mechanical tests, respectively, indicate that Young’s and storage moduli increase with PG concentration. The reinforcement of PBAT aims at modifying and tailoring the mechanical and viscoelastic properties of the material to expand its application field especially in the food and agricultural packaging sector, thanks to the similarity of PBAT performance with polyethylene

Preparation and characterization of innovative poly(butylene adipate terephthalate)-based biocomposites for agri-food packaging application

The present work reports on the preparation and subsequent mechanical, morphological and thermal characterization of composites based on poly(butylene adipate terephthalate) (PBAT), reinforced with micro-particles of inorganic bioabsorbable calcium-phosphate glass (CPG) at different contents up to 40 wt%. The PBAT-CPG composites were prepared by solvent casting. The resulting composite pellets were used for the injection molding of model 1BA specimens, according to standard UNI EN ISO 527. PBAT-CPG composites displayed an effective increase of the Young's modulus (E) up to 82% with respect to the pristine polymer, while showing a reduction of the yield stress (σy) up to 20%, of the stress at break (σB) up to 46%, of the strain at break (εB) up to 57% and of the toughness (T) up to 72%. The values of E, σy and σB were also compared and validated with theoretical values calculated using Kerner’s and Pukanszky’s models. Scanning electron microscopy (SEM) images display homogeneous dispersion and distribution of the filler particles in the polymer matrix with no aggregates or phase separation that would cause a deterioration of the material properties. Infrared (IR) spectroscopy did not show structural variations of the polymer matrix due to the CPG presence. The oxygen permeability in PBAT-based samples assumes significantly lower values when benchmarked with the permeability of low-density polyethylene (LDPE). Among the different composites, a decrease in oxygen permeability is observed as the CPG concentration increases. Regarding water vapor permeability, PBAT-based samples show a lower barrier effect than PE: in particular, permeability to water vapor assumes an increasing trend as the quantity of filler increases. The tuneable degradability of the final composite materials was defined by the disintegration degree (DD) determination under composting conditions in a laboratory-scale reactor. The developed materials prove to be valid biodegradable and eco-friendly alternatives to traditional thermoplastic polymers, such as LDPE, and can be applied in many fields, especially in package and mulch film applications

Preparation and characterization of innovative poly(butylene adipate terephthalate)‐based biocomposites for agri‐food packaging application

The present work reports on the preparation and subsequent mechanical, morphological and thermal characterization of composites based on poly(butylene adipate terephthalate) (PBAT), reinforced with micro-particles of inorganic bioabsorbable calcium-phosphate glass (CPG) at different contents up to 40 wt%. The PBAT-CPG composites were prepared by solvent casting. The resulting composite pellets were used for the injection molding of model 1BA specimens, according to standard UNI EN ISO 527. PBAT-CPG composites displayed an effective increase of the Young's modulus (E) up to 82% compared to the pristine polymer, while showing a reduction of the yield stress (σy) up to 20%, of the stress at break (σB) up to 46%, of the strain at break (εB) up to 57% and of the toughness (T) up to 72%. The values of E, σy and σB were also compared and validated with theoretical values calculated using Kerner's and Pukanszky's models. Scanning electron microscopy (SEM) images display homogeneous dispersion and distribution of the filler particles in the polymer matrix with no aggregates or phase separation that would cause a deterioration of the material properties. Infrared (IR) spectroscopy did not show structural variations of the polymer matrix due to the CPG presence. The oxygen permeability in PBAT-based samples assumes significantly lower values when benchmarked with the permeability of low-density polyethylene (LDPE). Among the different composites, a decrease in oxygen permeability is observed as the CPG concentration increases. Regarding water vapor permeability, PBAT-based samples show a lower barrier effect than polyethylene (PE): in particular, permeability to water vapor assumes an increasing trend as the quantity of filler increases. The tuneable degradation of the final composite materials was defined by the disintegration degree (DD) determination under composting conditions in a laboratory-scale reactor. The developed materials prove to be valid biodegradable and eco-friendly alternatives to traditional thermoplastic polymers, such as LDPE, and can be applied in many fields, especially in package and mulch film applications

Emergence of Leadership in a Group of Autonomous Robots

For modern biology and ethology, the reason for the emergence of leaders-followers patterns in groups of living organisms, is the need of social coordination. In this paper we attempt to examine factors contributing to the emergence of leadership, trying to understand the relation between leader role and behavioral capabilities. In order to achieve this goal, we use a simulation technique where a group of foraging robots has to choose between two identical food zones. Thus, robots must coordinate in some way in order to select the same food zone and collectively gathering food. Behavioral and quantitative analysis indicate that a form of leadership emerges and the emergence of leadership relates with high level of fitness. Moreover, we show that more skilled individuals in a group tend to assume a leadership role, in agreement with literature

Asymmetric posterior reversible encephalopathy syndrome in patient with hyperplastic anterior choroidal artery

We describe a case of asymmetric PRES due to the presence of hyperplastic anterior choroidal artery (AChA) in a man affected by sever hypertension. Posterior reversible encephalopathy syndrome (PRES) has become synonymous with a unique pattern of brain vasogenic edema and predominates in the parietal and occipital regions, accompanied by clinical neurological alterations. Sever hypertension is a risk factor that exceeds the limits of brain autoregulation, leading to breakthrough brain edema. In our knowledge this is the first case reported in literature, in which a similar vascular abnormality is linked to a PRES syndrome