Collective behaviours: from biochemical kinetics to electronic circuits

In this work we aim to highlight a close analogy between cooperative behaviors in chemical kinetics and cybernetics; this is realized by using a common language for their description, that is mean-field statistical mechanics. First, we perform a one-to-one mapping between paradigmatic behaviors in chemical kinetics (i.e., non-cooperative, cooperative, ultra-sensitive, anti-cooperative) and in mean-field statistical mechanics (i.e., paramagnetic, high and low temperature ferromagnetic, anti-ferromagnetic). Interestingly, the statistical mechanics approach allows a unified, broad theory for all scenarios and, in particular, Michaelis-Menten, Hill and Adair equations are consistently recovered. This framework is then tested against experimental biological data with an overall excellent agreement. One step forward, we consistently read the whole mapping from a cybernetic perspective, highlighting deep structural analogies between the above-mentioned kinetics and fundamental bricks in electronics (i.e. operational amplifiers, flashes, flip-flops), so to build a clear bridge linking biochemical kinetics and cybernetics.Comment: 15 pages, 6 figures; to appear on Scientific Reports: Nature Publishing Grou

Percorsi a ‘sguardi multipli’: sfide e riflessioni sulla costruzione di pratiche decoloniali in università

‘Multiple Gaze’ Paths: Challenges and Reflections on the Construction of Decolonial Practices in the University. Reconstructing dynamics that emerged from a project on literary texts and racism in Italy, proposed in 2021 in the Department of Modern Languages, Literatures and Cultures at the University of Bologna, the article aims to reflect on the positive aspects, limits and critical issues of the path. The reflection will focus on specific aspects related to the project: the methods and choices of developing the work carried out with students, colleagues and teachers; the central role of the connection between text, body and experiences of racialized authors; the questioning of the rigid opposition between artistic quality and political value of literary works; and the need for cultural productions based on listening to historically marginalized voices. The proposed analysis will also be connected to broader aspects: the gap between anti-racist and decolonial projects and the real democratization of university; the question of responsibility, positioning and privilege in the university; the challenges posed by the “professionalising” insertion of professors into the neoliberal university system and the geopolitics of power in which this reality operates; and the importance of continuing to enact practices of decolonizing teaching and research, while being aware of the limits of these attempts. Finally, it will be proposed to interpret the university as a ‘crossing space’ in order to deconstruct the rhetoric of belonging and permanence – namely, ‘being of the university’ – and promote the idea of a space of connections that is open and capable of building transformative networks and alliances

« si brusquement tu cesses d’exister » : neruda/minghella ; moment du poème, vacillement du traduire, l’instance du trouvé-créé, dans truly, madly, deeply

A partir d’un fragment de Neruda prononcé en stéréophonie dans une scène de traduction et de revenance qui est le pivot poétique et le kairos du film de Minghella, Truly, Madly, Deeply, cet article propose de montrer comment ce moment du poème, suspendu entre deux langues, fait brèche dans l’écriture du film, pour créer une ouverture par laquelle on spirale hors-récit et hors-langue vers le lieu de la lecture pure. Afin d’éclairer ce lieu sont posées les questions de l’adresse de l’absent(e), et celle de la destination de l’écrit. Ce moment poétique, d’un flottement, est le lieu de notre questionnement, un moment suspendu à la menace d’une perte de sens

Congenital mirror movements in a new Italian family

Mirror movements (MMs) occur on the contralateral side of a limb being used intentionally. Because few families with congenital MMs and no other neurological signs have been reported, the underlying mechanisms of MMs are still not entirely clear. We report on the clinical, genetic, neurophysiological and neuroimaging findings of 10 of 26 living members of a novel four-generation family with congenital MMs. DCC and RAD51 were sequenced in affected members of the family. Five of the ten subjects with MMs underwent neurophysiological and neuroimaging evaluations. The neurophysiological evaluation consisted of electromyographic (EMG) mirror recordings, investigations of corticospinal excitability, and analysis of interhemispheric inhibition using transcranial magnetic stimulation techniques. The neuroimaging evaluation included functional MRI during finger movements. Eight (all females) of the ten members examined presented MMs of varying degrees at the clinical assessment. Transmission of MMs appears to have occurred according to an autosomal-dominant fashion with variable expression. No mutation in DCC or RAD51 was identified. EMG mirror activity was higher in MM subjects than in healthy controls. Short-latency interhemispheric inhibition was reduced in MM subjects. Ipsilateral motor-evoked potentials were detectable in the most severe case. The neuroimaging evaluation did not disclose any significant abnormalities in MM subjects. The variability of the clinical features of this family, and the lack of known genetic abnormalities, suggests that MMs are heterogeneous disorders. The pathophysiological mechanisms of MMs include abnormalities of transcallosal inhibition and corticospinal decussatio

Replica symmetry breaking in mean field spin glasses trough Hamilton-Jacobi technique

During the last years, through the combined effort of the insight, coming from physical intuition and computer simulation, and the exploitation of rigorous mathematical methods, the main features of the mean field Sherrington-Kirkpatrick spin glass model have been firmly established. In particular, it has been possible to prove the existence and uniqueness of the infinite volume limit for the free energy, and its Parisi expression, in terms of a variational principle, involving a functional order parameter. Even the expected property of ultrametricity, for the infinite volume states, seems to be near to a complete proof. The main structural feature of this model, and related models, is the deep phenomenon of spontaneous replica symmetry breaking (RSB), discovered by Parisi many years ago. By expanding on our previous work, the aim of this paper is to investigate a general frame, where replica symmetry breaking is embedded in a kind of mechanical scheme of the Hamilton-Jacobi type. Here, the analog of the "time" variable is a parameter characterizing the strength of the interaction, while the "space" variables rule out quantitatively the broken replica symmetry pattern. Starting from the simple cases, where annealing is assumed, or replica symmetry, we build up a progression of dynamical systems, with an increasing number of space variables, which allow to weaken the effect of the potential in the Hamilton-Jacobi equation, as the level of symmetry braking is increased. This new machinery allows to work out mechanically the general K-step RSB solutions, in a different interpretation with respect to the replica trick, and lightens easily their properties as existence or uniqueness.Comment: 24 pages, no figure

Notes on the p-spin glass studied via Hamilton-Jacobi and Smooth-Cavity techniques

In these notes, we continue our investigation of classical toy models of disordered statistical mechanics through various techniques recently developed and tested mainly on the paradigmatic SK spin glass. Here we consider the p-spin-glass model with Ising spins and interactions drawn from a normal distribution N[0,1]. After a general presentation of its properties (e.g. self-averaging of the free energy, existence of a suitable thermodynamic limit), we study its equilibrium behavior within the Hamilton-Jacobi framework and the smooth cavity approach. Through the former we find both the RS and the 1RSB expressions for the free energy, coupled with their self-consistent relations for the overlaps. Through the latter, we recover these results as irreducible expression, and we study the generalization of the overlap polynomial identities suitable for this model; a discussion on their deep connection with the structure of the internal energy and the entropy closes the investigation.Comment: To appear on JM

Biocompounds recovery from Spirulina by conventional and ohmic heating methodologies: chemical and biological properties

Extracting the totality of bio-compounds with industrial interest from Cyanobacterium is often prevented by the intrinsic rigidity of its cell wall. In this sense, the present study focuses on evaluating the influence thermal batch extraction (conventional extraction technologies) and ohmic heating (OH) assisted extraction (considered a greener alternative technology) in blue green microalgae Arthrospira platensis (Spirulina) cell disruption for bioactive fractions recovery. The proximal composition of Spirulina was initially determined. The maximum protein content (i.e., CPhycocyanin), total carbohydrates (TC) and total phenolic compounds (TPC) extracted in water at different times (30-120 min) and temperatures (30-51 ºC) was quantified after the conventional and OH- assisted extraction. The freeze-thawing process was used as control. The antioxidant activity (i.e., FRAP and DPPH assays) of the obtained extracts was assessed. Results showed that with the freeze-thawing process, traditionally used for the recovery of bio- compounds from Spirulina, the concentration of C-phycocyanin was approx. 42 mg/g of Spirulina, 26 mgGlcE/g Spirulina of TC and 9 mgGAE/g Spirulina of TPC. Using OH-assisted extraction, the maximum of C-Phycocyanin content obtained was 45 mg/g of Spirulina (obtained at 37 ºC, 30 min), the maximum carbohydrates content was 40 mgGlcE/g Spirulina and the maximum TPC was 10 mgGAE/g Spirulina. On the other hand, using conventional thermal treatment it can be observed that, under the same conditions, the bioactive compounds recovery decreased to 35 mg/g, 20 mgGlcE/g Spirulina for C-phycocyanin concentration and TC (p<0.05), respectively. The concentration in phenolic compounds is not so affected, but even so the ohmic heating potentiates the extraction of these secondary metabolites. The antioxidant activity of the extracts there was not different between conventional treatments andOH. Thus, the results indicated that OH is a good alternative to conventional methods aiming at the extraction of intracellular components with a decrease in processing time and energy costs associated with the extraction process, which together with an easy upscale make OH an interesting methodology for use in the industrial production of microalgae colorants and bioactive supplements.info:eu-repo/semantics/publishedVersio

The Impact of a Community-Based Childhood Obesity Prevention Program on Children’s Physical Activity and Fitness

The purpose of this study is to determine the effects of South County Food, Fitness and Fun (SCFFF), a 16-week community-based obesity prevention program, on children’s moderate to vigorous physical activity (MVPA), physical fitness, body mass index (BMI), and BMI z-score. A non-randomized pre-test and post-test study design was used to assess changes in MVPA, physical fitness, BMI and BMI z-score from baseline to program end. MVPA was measured by accelerometer, physical fitness measured by Fitnessgram, and height and weight were measured by stadiometer and scale and used to calculate BMI. The analytic sample for this study included 53 children from nine SCFFF programs conducted between 2011-2016. There was a significant increase in the percentage of time children spent participating in MVPA (1.12%; p=0.022), curl-ups (p\u3c0.001) and trunk lifts (p=0.004). BMI z-score decreased (p\u3c0.001). Results reinforce the importance of offering community-based interventions that include caregivers to prevent excess weight gain in children

Ferromagnetic models for cooperative behavior: Revisiting Universality in complex phenomena

Ferromagnetic models are harmonic oscillators in statistical mechanics. Beyond their original scope in tackling phase transition and symmetry breaking in theoretical physics, they are nowadays experiencing a renewal applicative interest as they capture the main features of disparate complex phenomena, whose quantitative investigation in the past were forbidden due to data lacking. After a streamlined introduction to these models, suitably embedded on random graphs, aim of the present paper is to show their importance in a plethora of widespread research fields, so to highlight the unifying framework reached by using statistical mechanics as a tool for their investigation. Specifically we will deal with examples stemmed from sociology, chemistry, cybernetics (electronics) and biology (immunology).Comment: Contributing to the proceedings of the Conference "Mathematical models and methods for Planet Heart", INdAM, Rome 201