The Concept of Necropolitics during the Pandemic of Covid-19 in Brazil

The present article aims to reflect the access to health in Brazil, especially in the current context of the Covid-19 pandemic, establishing theoretical and conceptual paradigms between the fields of biopolitics and necropolitics. In this context, this study analyses the political discourses during the pandemic of Covid-19 in Brazil. The methodology comes from a bibliographic review, based on the hypothetical-deductive method, mostly based on the concept of necropolitics. Finally, it has been observed that even more dangerous than the virus itself is the necropolitical perspective that dictates who lives and who dies – in this case, who breathes and who suffocates - the nation’s economy over human lives. It’s also been verified that the admission of certain health protocols, under the bioethical perspective, portray the death policy that dictates who lives and who dies in a State completely ineffective in its political, social and even economic dimensions

The two-site Bose--Hubbard model

The two-site Bose--Hubbard model is a simple model used to study Josephson tunneling between two Bose--Einstein condensates. In this work we give an overview of some mathematical aspects of this model. Using a classical analysis, we study the equations of motion and the level curves of the Hamiltonian. Then, the quantum dynamics of the model is investigated using direct diagonalisation of the Hamiltonian. In both of these analyses, the existence of a threshold coupling between a delocalised and a self-trapped phase is evident, in qualitative agreement with experiments. We end with a discussion of the exact solvability of the model via the algebraic Bethe ansatz.Comment: 10 pages, 5 figures, submitted for publication in Annales Henri Poincar

Behaviour of the energy gap in a model of Josephson coupled Bose-Einstein condensates

In this work we investigate the energy gap between the ground state and the first excited state in a model of two single-mode Bose-Einstein condensates coupled via Josephson tunneling. The energy gap is never zero when the tunneling interaction is non-zero. The gap exhibits no local minimum below a threshold coupling which separates a delocalised phase from a self-trapping phase which occurs in the absence of the external potential. Above this threshold point one minimum occurs close to the Josephson regime, and a set of minima and maxima appear in the Fock regime. Analytic expressions for the position of these minima and maxima are obtained. The connection between these minima and maxima and the dynamics for the expectation value of the relative number of particles is analysed in detail. We find that the dynamics of the system changes as the coupling crosses these points.Comment: 12 pages, 5 .eps figures + 4 figs, classical analysis, perturbation theor

Integrable Impurity Spin Ladder Systems

Two integrable spin ladder systems with different types of impurities are proposed. The impurities are introduced in such a way that the integrability of the models is not violated. The models are solved exactly and the Bethe ansatz equations as well as the energy eigenvalues are obtained. We show for both models that a phase transition between gapped and gapless spin excitations occurs at a critical value of the rung coupling J. In addition, the dependence of the impurities on this phase transition is determined explicitly. Remarkably, in one of the models a decreasing of the spin gap with increasing impurity strength is found.Comment: 11 pages, 3 eps figure

Control of tunneling in an atomtronic switching device

The precise control of quantum systems will play a major role in the realization of atomtronic devices. As in the case of electronic systems, a desirable property is the ability to implement switching. Here we show how to implement switching in a model of dipolar bosons confined to three coupled wells. The model describes interactions between bosons, tunneling of bosons between adjacent wells, and the effect of an external field. We conduct a study of the quantum dynamics of the system to probe the conditions under which switching behavior can occur. The analysis considers both integrable and non-integrable regimes within the model. Through variation of the external field, we demonstrate how the system can be controlled between various switched-on and switched-off configurations.Comment: Revised Communications Physics (open access) version; Major revision: 8 pages, 6 figures; Supplementary material: 2 pages, 5 figure

Classical and quantum dynamics of a model for atomic-molecular Bose--Einstein condensates

We study a model for a two-mode atomic-molecular Bose--Einstein condensate. Starting with a classical analysis we determine the phase space fixed points of the system. It is found that bifurcations of the fixed points naturally separate the coupling parameter space into four regions. The different regions give rise to qualitatively different dynamics. We then show that this classification holds true for the quantum dynamics.Comment: 13 pages, 7 eps figure

.

L \u27autore, rappresentante della Sinistra triestina, affronta alcune tematiche storiche che hanno interessato il dibattito politico e storiografico italiano negli ultimi anni, in particolar modo le foibe e l \u27esodo dall \u27Istria, analizzando i motivi della loro rimozione da parte della Sinistra italiana fino ad anni a noi recenti.Kao pripadnik trséanske ljevice, autor razmatra neke povijesne teme koje su posljednjih godina aktualizirane u okviru suvremenih politickih i povijesno-znanstvenih rasprava, osobito problem masovnih grobnica i iselj avanj a iz lstre analizirajuéi ujedno razloge zbog kojih je ta pitanja talijanska ljevica otklanjala sve do najnovijih dana