Parthenope University of Naples
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Travelling pulses in the Barkley model: A geometric singular perturbation approach
No full textIn this work, we investigate travelling pulse solutions to the Barkley model, a prototypical example of excitable system with activator-inhibitor dynamics. Such patterns are numerically observed for a wide range of parameter values and show how coherent structures can be induced by mechanisms different from diffusion-driven instability. The intrinsic multiscale nature of this system allows us to apply Geometric Singular Perturbation Theory (GSPT) to constructively establish the existence of travelling pulses as homoclinic orbits in the corresponding three-dimensional phase-space. The analytical findings are corroborated by a thorough numerical investigation via direct simulation as well as continuation based on the software AUTO
Bio-electrosynthesis of polyhydroxybutyrate and surfactants in microbial fuel cells: a preliminary study
No full textMicrobial Electrochemical Technology (MET) offers a promising avenue for CO2 utilization by leveraging the ability of chemolithotrophic microorganisms to use inorganic carbon in biosynthetic processes. By harnessing the power of electroactive bacteria, METs can facilitate the conversion of inorganic carbon into organic compounds. Therefore, this work combines biosurfactant production at the anode and PHB production at the cathode of Microbial Fuel Cells (MFCs), while testing the efficiency of Microbial Electrosynthesis Cells (MECs), and traditional culture in liquid media. This study employed a consortium of Pseudomonas aeruginosa PA1430/CO1 and Shewanella oneidensis MR-1, to provide reducing equivalents to Cupriavidus necator DSM428 for CO2 fixation and polyhydroxybutyrate (PHB) production. Glycerol was used as a carbon source by the anode consortium to investigate biosurfactant production. Additionally, Adaptive Laboratory Evolution (ALE) was employed to enhance the efficiency of this process to develop biofilms capable of synthesizing PHB from CO2 in MFCs under a controlled gas atmosphere (10% CO2, 10% O2, 2% H2, 78% N2). Observed results showed a higher direct CO2 removal from the gas mix in MECs (73%) than in MFCs (65%) compared to control cultures. Anionic (18.8 mg/L) and non-ionic (14.6 mg/L) surfactants were primarily present at the anodes of MFCs. Confocal microscope analysis revealed that the accumulation of PHBs in C. necator was significantly higher in MFCs (73% of cell volume) rather than in MECs (23%) and control cultures (40%). Further analyses on metabolites in the different systems are ongoing. Our data gave evidence that the anode consortium was able to provide enough electrons to sustain the chemolithotrophic growth of C. necator and the biosynthesis of PHBs at the cathode of MFCs, in a mechanism suggestive of the direct interspecies electron transfer (DIET), naturally occurring in natural environment
Scenarios of fuel vector trajectories in the Italian road vehicle fleet to 2030 and their impacts on EU GHG reduction targets
No full textThe transport sector’s decarbonization remains a critical challenge in reducing greenhouse gas (GHG) emissions and achieving the EU Green Deal 2030 targets (−43.7% with respect to 2005). This article develops forecasts for 2030 to assess the potential reduction in tank-to-wheel (TtW) and well-to-wheel (WtW) GHG emissions within the Italian road transportation sector. Two tendential scenarios, namely, “High Decarbo” and “Moderate Decarbo,” are constructed based on differing hypotheses and on adoption rates of measures and policies aimed at promoting sustainable transportation (e.g., subsidies for electric vehicles) that are already in effect. The “Moderate Decarbo” forecasts project a 12% TtW and a 15% WtW GHG emissions reduction compared to 2005 levels. Under favorable assumptions, GHG emissions could potentially be reduced by 28% TtW and 33% WtW, nearing EU targets but still falling below them. The impact of electrification has been broken down, and the hybrid electric vehicle (HEV) contribution on GHG reduction is expected to be very close to that of battery electric vehicles (BEVs), underlining the advantages that an increased spread of HEVs might have, in addition to the BEVs. The introduction of the law-required quantities of second-generation biofuels is the main driver for the higher WtW reductions. Two more “trend-breaking” 2030 scenarios are developed in which biofuels are spread, maximizing the Italian production capabilities to abate the environmental impact of the freight sector. In the High Decarbo scenario, the WtW GHG emissions reduction is up to 40%, demonstrating the impact that a smart use of biofuels might have
Bio-Chronostratigraphy and Facies character of the Upper Cretaceous carbonates of the Coste Chiavarine Formation in the north Venafro Mountains (Central Apennines, Italy).
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Prefazione al vol.: Cantieri di linguaggi. Ricerca e didattica sperimentale per lo sviluppo espressivo e di creatività
No full textThe Expanding Nexus of Conflict: Multidimensional Struggles across Discourses and Domains
No full textConflict is an intrinsic aspect of human interaction which emerges in both overt and subtle ways across various communicative contexts. By definition, conflict has traditionally been associated with physical confrontation, warfare, and political unrest, yet from a sociolinguistic and discourse analytical perspective, the concept extends well beyond such associations. The manner in which individuals and groups negotiate power, identity, and ideology through language is, in fact, inevitably, even naturally, imbued with opposition. From a discursive standpoint therefore, conflict is not merely an outcome of opposing positions but a dynamic process that unfolds through competing narratives where language plays a crucial role. Discursive strategies such as mitigation, polarisation and purposeful ambiguity are frequently employed to frame ideological struggles in particular ways, reinforcing or contesting existing power structures. Conflict is also central to identity construction and group belonging. It can emerge at the intersection of ethnicity, gender, class, and other social variables, as linguistic choices and communicative styles become sites of struggle over legitimacy and representation
Exploring the dark side of entrepreneurial team diversity: A post-mortem analysis of failed start-ups
No full textThis study challenges the predominantly positive view of entrepreneurial team diversity by exploring its negative effects on start-up survival across different development stages. Drawing on secondary data from interviews of failed start-ups retrieved from the Failory database, triangulated with additional publicly available sources of evidence, the research employs an inductive qualitative analysis grounded in the Gioia method and a retrospective approach, to examine which demographic, informational, personality, and cognitive diversity characteristics contribute to failure during the idea, product development, and launch stages. Findings reveal that personality and cognitive diversity are critical in idea development, personality and informational diversity during product development, and personality and demographic diversity during the launch stage. Adopting a dynamic perspective, the study deepens the understanding of team dynamics and venture survival in the entrepreneurial context. The findings guide managers and policymakers on leveraging diversity as a strategic asset while addressing challenges throughout the venture’s lifecycle
Trust in municipal government and recycling behaviour
No full textThis paper contributes to the literature on institutional trust by examining the relationship between household waste recycling behaviour and two key dimensions of local governance: trust in municipal governments and the perceived quality of the municipal public services. Using data from the Italian National Statistical Office’s Aspects of Daily Life survey (2018–2021), we investigate whether higher levels of trust in local institutions and more positive evaluations of the services provided are associated with greater engagement in recycling practices. We use non-linear regression models and carry out robustness checks to test the consistency of the results. The findings reveal a positive and statistically significant correlation between trust in municipal governments and recycling behaviour, whereas trust in other public institutions — such as the European Parliament, the national Parliament, and regional governments — shows no significant association. These associations are more pronounced in Northern Italy compared to Central and Southern Italy, and in the years preceding the COVID-19 pandemic. The perceived quality of the municipal public services also highlights a consistent positive correlation with recycling behaviour