Sistemas alimentarios, semillas y complejidad : una mirada al sistema alimentario colombiano

El presente artículo de investigación aborda un fenómeno que resulta tan vital como relevante para la humanidad: las semillas, su producción, comercialización, utilización y control. Desde la perspectiva de las ciencias de la complejidad, se efectúa un proceso de observancia y análisis de fenómenos que se manifiestan en el marco de sistemas complejos, específicamente sistemas alimentarios. Por consiguiente, se lleva a cabo una caracterización del sistema alimentario colombiano, a la vez que se referencia el sistema alimentario global a partir de una visión de la fractalidad. Así mismo, se analizan fenómenos complejos tales como acciones sociales de auto organización y manifestaciones de inteligencia de enjambre, en torno a la protección de semillas nativas y saberes ancestrales de la agricultura, a nivel regional y local.This paper approaches a phenomenon as vital as it is relevant for humanity: production, distribution, use and control of seeds. An analysis of phenomena manifested in the framework of complex systems is brought about by complexity science perspective, specifically food systems. Henceforth, it is carried out a characterization of Colombian food system, while global food system is alluded from a vision of fractality. Likewise, it is pursued an analysis of complex phenomena as social actions of self-organization and swarm intelligence demonstrations, around the protection of native seeds and ancestral knowledge of agriculture, in a regional and local level

Bordering Through Exemption: Extracontinental Migration Flows in Mexico

This paper examines Mexico’s governmentality of extracontinental migration in transit to the United States. It argues that, in the context of transit control regimes, exemption is instrumentalised as a bordering mechanism and practice in which transit states assume, react and utilise their role as a ‘transit’ country. By drawing on statistical information about migrant populations from Asia and Africa intercepted by Mexican authorities from 2010 to 2019, four arrangements are identified: (1) sporadic expulsion, (2) regularisation façade, (3) guardianship and (4) self-deportation. The analysis sheds light on the transformative and adaptive dimension of the Mexican Transit Control Regime and how this is geared towards maintaining its focus on intercepting and deterring Central American migrants in transit to the United States

Quantum gravitational corrected evolution equations of charged black holes

We explain how quantum gravity, treated as an effective field theory, might modify the evaporative evolution of a four-dimensional, non-extremal, non-rotating, charged black hole. With some approximations, we derive a set of coupled differential equations describing the charge and mass of the black hole as a function of time. These equations represent a generalisation of the analogous ones already present in the literature for classical black holes.Comment: 12 pages; accepted for publication in JHA

Lyapunov exponents in N=2\mathbf{{\cal N}=2} supersymmetric Jackiw-Teitelboim gravity

We study $\mathcal{N}=2$ supersymmetric Jackiw-Teitelboim (JT) gravity at finite temperature coupled to matter. The matter fields are related to superconformal primaries by AdS/CFT duality. Due to broken super reparametrisation invariance in the SCFT dual, there are corrections to superconformal correlators. These are generated by the exchange of super-Schwarzian modes which is dual to the exchange of 2D supergravity modes. We compute corrections to four-point functions for superconformal primaries and analyse the behaviour of out-of-time-ordered correlators. In particular, four-point functions of two pairs of primaries with mutually vanishing two-point functions are considered. By decomposing the corresponding supermultiplet into its components, we find different Lyapunov exponents. The value of the Lyapunov exponents depends on whether the correction is due to graviton, gravitini or graviphoton exchange. If mutual two-point functions do not vanish all components grow with maximal Lyapunov exponent.Comment: 13 pages, v2: reference adde

Influence of homeostatic mechanisms of bacterial growth and division on structural properties of biofilms. A computer simulation study

Bacterial growth and division generally occur by the process known as binary fission, in which the cells grow polarly until they divide into two daughter cells. Although this process is affected by factors that introduce stochastic variability in both growth rate and daughter cell length, the fact is that the size distribution in bacterial communities, also known as biofilm, remains stable over time. This suggests the existence of homeostatic mechanisms that contribute to maintaining a stable size distribution. Those known as sizer and adder stand out among these mechanisms whose relevance is not entirely determined. In this work, computer simulations using an agent-based model, are used to study the effect of these homeostatic mechanisms on the geometrical and structural properties of the developing biofilm, focusing on the early stages of its development. Also, it was examined the effect of linear or exponential dependence with the time of cellular growth on these properties. From our study, we deduce that these mechanisms do not have a noticeable impact on the properties studied, which could be due to the importance that stochastic factors play in the cell division and growth process. In addition, we discuss how competition between cell growth and diffusion is a key aspect in explaining the structure and geometry of developing bacterial colonies

Raman-scattering study of the phonon dispersion in twisted bi-layer graphene

Bi-layer graphene with a twist angle \theta\ between the layers generates a superlattice structure known as Moir\'{e} pattern. This superlattice provides a \theta-dependent q wavevector that activates phonons in the interior of the Brillouin zone. Here we show that this superlattice-induced Raman scattering can be used to probe the phonon dispersion in twisted bi-layer graphene (tBLG). The effect reported here is different from the broadly studied double-resonance in graphene-related materials in many aspects, and despite the absence of stacking order in tBLG, layer breathing vibrations (namely ZO' phonons) are observed.Comment: 18 pages, 4 figures, research articl

Schwarzschild-type black holes in Starobinsky-Bel-Robinson gravity

We study physical properties of a Schwarzschild-type black hole in the framework of the recently proposed Starobinsky-Bel-Robinson (SBR) modified theory of gravity, working perturbatively in the new coupling constant. In particular, we compute the temperature, entropy, pressure and lifetime of a Schwarzschild-type black hole.Comment: 10 pages; v3: one more reference added, final version accepted for publication in Physics Letters

Arbitrary Detention of Mexican Citizens by Mexican Immigration Authorities

On 3 September 2015, Mexican immigration authorities detained four Indigenous Tzeltal Mexicans who were travelling by bus to the northern state of Sonora. Despite identifying themselves as Mexican citizens, the authorities considered their documents false, and they were detained for nine days until their identities were certified. The Mexican State took four years to acknowledge publicly and apologise for this arbitrary detention. Similarly, in 2017, a 39‑year‑old man born in Oaxaca, living in the streets of Puebla after being deported by the United States Government, was detained for being ‘identified’ as a Salvadorian citizen by Mexican authorities. However, it would be a mistake to consider these cases an exception or anomaly in the Mexican Transit Control Regime. Drawing on statistical and archival information from 2010 to 2020, as well as semi-structured interviews conducted in 2021, in this article, we examine the arbitrary detention of Mexican citizens by Mexican immigration authorities. We highlight the multiple rights violated, question how these detentions have been framed in the official discourse and examine the outcome of these detentions. Our analysis sheds light on the racialisation of migration control in Mexico