Philosophy and childhood: theory and practice

An introduction to the Special Issu

Education Professionals and the COVID-19 Pandemic : Turning Crisis into New Opportunities

The COVID-19 pandemic emergency brought human vulnerability to the proscenium revealing the uncertainty associated with existence. It appears as a symptom of a deeper crisis of modern society, whose paradigms need to be questioned. Could this be an oppor-tunity, though? The qualitative study presented here aimed to investigate the emotions experienced and the responses developed by the education professionals during the first lockdown. It explored the areas related to motivation, fears, and the ideas prompted by the change, with a focus on the conditions able to foster “creative solutions”. Teamwork and the presence of training programs appear to be crucial elements

Universal upper limit on inflation energy scale from cosmic magnetic field

Recently observational lower bounds on the strength of cosmic magnetic fields were reported, based on gamma-ray flux from distant blazars. If inflation is responsible for the generation of such magnetic fields then the inflation energy scale is bounded from above as rho_{inf}^{1/4} < 2.5 times 10^{-7}M_{Pl} times (B_{obs}/10^{-15}G)^{-2} in a wide class of inflationary magnetogenesis models, where B_{obs} is the observed strength of cosmic magnetic fields. The tensor-to-scalar ratio is correspondingly constrained as r< 10^{-19} times (B_{obs}/10^{-15}G)^{-8}. Therefore, if the reported strength B_{obs} \geq 10^{-15}G is confirmed and if any signatures of gravitational waves from inflation are detected in the near future, then our result indicates some tensions between inflationary magnetogenesis and observations.Comment: 12pages, v2: several discussions and references added, version accepted for publication by JCA

To bi or not to bi? La bisessualità in Italia tra cancellazione, stereotipi e affermazione di sé: le sfide per l’educazione

Verso la bisessualità si è sviluppato nel tempo uno spettro di pratiche oppressive (bi-negatività) che includono forme di violenza, discriminazione, denigrazione e cancellazione epistemica: la sua esistenza viene ancora frequentemente negata (bi-erasure) oppure associata a manifestazioni di tipo patologico. Le evidenze scientifiche mostrano come la bi-negatività abbia impatti significativi sulla qualità della vita dei soggetti bi. Con l’obiettivo di approfondire quali siano i contesti e quali gli atteggiamenti, i comportamenti e le esperienze che possono favorire (oppure ostacolare) i vissuti positivi dei soggetti bisessuali – delineando così possibili piste di intervento educativo – è stata condotta un’indagine esplorativa che ha coinvolto complessivamente 519 individui bisessuali italiani (N=519). La raccolta dati è avvenuta a ottobre-novembre 2020, attraverso un questionario semi-strutturato online e i dati qualitativi sono stati codificati. La comunità LGBTQ+ e le relazioni con altri soggetti bi si mostrano come i contesti relazionali più favorevoli al benessere delle persone rispondenti, mentre il contesto familiare e la rappresentazione mediatica vengono riportati quali elementi di maggiore ostacolo. Fra gli elementi a favore di vissuti positivi emergono la possibilità di avere accesso a materiale informativo e/o a testimonianze di soggetti bisessuali e il vivere in contesti relazionali aperti e plurali. Fra gli aspetti più critici, invece, quelli legati alla scarsa (o superficiale) conoscenza sul tema, che alimenta bi-cancellazione e discriminazione. L’indagine pone in evidenza la necessità di informazione e formazione specifica nell’ambito dell’educazione degli adulti, l’urgenza di favorire contesti in cui il pensiero favorisca la decostruzione di stereotipi e pregiudizi e l’esigenza di un’educazione all’affettività, alla sessualità e alle tematiche LGBTQ+ che aiuti a costruire una nuova cultura della sessualità

Magnetic field generation in Higgs inflation model

We study the generation of magnetic field in Higgs-inflation models where the Standard Model Higgs boson has a large coupling to the Ricci scalar. We couple the Higgs field to the Electromagnetic fields via a non- renormalizable dimension six operator suppressed by the Planck scale in the Jordan frame. We show that during Higgs inflation magnetic fields with present value $10^{-6}$ Gauss and comoving coherence length of $100 kpc$ can be generated in the Einstein frame. The problem of large back-reaction which is generic in the usual inflation models of magneto-genesis is avoided as the back-reaction is suppressed by the large Higgs-curvature coupling.Comment: 10 pages, RevTeX

Standard Cosmology Delayed

The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.Comment: 12 pages, 3 figures, Revised with more elaborate discussions. Accepted for publication in JCA

Electric-magnetic duality and the conditions of inflationary magnetogenesis

The magnetogenesis scenarios triggered by the early variation of the gauge coupling are critically analyzed. In the absence of sources, it is shown that the electric and magnetic power spectra can be explicitly computed by means of electric-magnetic duality transformations. The remnants of a pre-inflationary expansion and the reheating process break explicitly electric-magnetic duality by inducing Ohmic currents. The generation of large-scale magnetic field and the physical distinction between electric and magnetic observables stems, in this class of models, from the final value reached by the conductivity of the plasma right after inflation. Specific numerical examples are given. The physical requirements of viable magnetogenesis scenarios are spelled out.Comment: 25 pages, 9 figure

Can slow roll inflation induce relevant helical magnetic fields?

We study the generation of helical magnetic fields during single field inflation induced by an axial coupling of the electromagnetic field to the inflaton. During slow roll inflation, we find that such a coupling always leads to a blue spectrum with $B^2(k) \propto k$, as long as the theory is treated perturbatively. The magnetic energy density at the end of inflation is found to be typically too small to backreact on the background dynamics of the inflaton. We also show that a short deviation from slow roll does not result in strong modifications to the shape of the spectrum. We calculate the evolution of the correlation length and the field amplitude during the inverse cascade and viscous damping of the helical magnetic field in the radiation era after inflation. We conclude that except for low scale inflation with very strong coupling, the magnetic fields generated by such an axial coupling in single field slow roll inflation with perturbative coupling to the inflaton are too weak to provide the seeds for the observed fields in galaxies and clusters.Comment: 33 pages 6 figures; v4 to match the accepted version to appear in JCA

Issues on Generating Primordial Anisotropies at the End of Inflation

We revisit the idea of generating primordial anisotropies at the end of inflation in models of inflation with gauge fields. To be specific we consider the charged hybrid inflation model where the waterfall field is charged under a U(1) gauge field so the surface of end of inflation is controlled both by inflaton and the gauge fields. Using delta N formalism properly we find that the anisotropies generated at the end of inflation from the gauge field fluctuations are exponentially suppressed on cosmological scales. This is because the gauge field evolves exponentially during inflation while in order to generate appreciable anisotropies at the end of inflation the spectator gauge field has to be frozen and scale invariant. We argue that this is a generic feature, that is, one can not generate observable anisotropies at the end of inflation within an FRW background.Comment: V3: new references added, JCAP published versio

Seminal magnetic fields from Inflato-electromagnetic Inflation

We extend some previous attempts to explain the origin and evolution of primordial magnetic fields during inflation induced from a 5D vacuum. We show that the usual quantum fluctuations of a generalized 5D electromagnetic field cannot provide us with the desired magnetic seeds. We show that special fields without propagation on the extra non-compact dimension are needed to arrive to appreciable magnetic strengths. We also identify a new magnetic tensor field $B_{ij}$ in this kind of extra dimensional theories. Our results are in very good agreement with observational requirements, in particular from TeV Blazars and CMB radiation limits we obtain that primordial cosmological magnetic fields should be close scale invariance.Comment: Improved version. arXiv admin note: text overlap with arXiv:1007.3891 by other author