Two-dimensional two-component plasma with adsorbing impurities

We study the behavior of the two-dimensional two-component plasma in the presence of some adsorbing impurities. Using a solvable model, we find analytic expressions for the thermodynamic properties of the plasma such as the $n$-body densities, the grand potential, and the pressure. We specialize in the case where there are one or two adsorbing point impurities in the plasma, and in the case where there are one or two parallel adsorbing lines. In the former case we study the effective interaction between the impurities, due to the charge redistribution around them. The latter case is a model for electrodes with adsorbing sticky sites on their surface

Cannibalism as a life boat mechanism

Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one

Lorentz invariance of entanglement classes in multipartite systems

We analyze multipartite entanglement in systems of spin-1/2 particles from a relativistic perspective. General conditions which have to be met for any classification of multipartite entanglement to be Lorentz invariant are derived, which contributes to a physical understanding of entanglement classification. We show that quantum information in a relativistic setting requires the partition of the Hilbert space into particles to be taken seriously. Furthermore, we study exemplary cases and show how the spin and momentum entanglement transforms relativistically in a multipartite setting.Comment: v2: 5 pages, 4 figures, minor changes to main body, journal references update

Gravity as a tool to improve the hydrologic mass budget in karstic areas

Monitoring the water movements in karstic areas is a fundamental but challenging task due to the complexity of the drainage system and the difficulty in deploying a network of observations. Gravimetry offers a valid complement to classical hydrologic measurements in order to characterize such systems in which the recharge process causes temporarily accumulation of large water volumes in the voids of the epi-phreatic system. We show an innovative integration of gravimetric and hydrologic observations that constrains a hydrodynamic model of the Škocjan cave system (Slovenia). We demonstrate how the inclusion of gravity observations improves water mass budget estimates for the Škocjan area based on hydrological observations only. Finally, the detectability of water storage variations in other karstic contexts is discussed with respect to the noise performances of spring and super-conducting gravimeters

Entropy Maximization in the Presence of Higher-Curvature Interactions

Within the context of the entropic principle, we consider the entropy of supersymmetric black holes in N=2 supergravity theories in four dimensions with higher-curvature interactions, and we discuss its maximization at points in moduli space at which an excess of hypermultiplets becomes massless. We find that the gravitational coupling function F^(1) enhances the maximization at these points in moduli space. In principle, this enhancement may be modified by the contribution from higher F^(g)-couplings. We show that this is indeed the case for the resolved conifold by resorting to the non-perturbative expression for the topological free energy.Comment: 22 pages, 8 figures, AMS-LaTe

Representation theory of some infinite-dimensional algebras arising in continuously controlled algebra and topology

In this paper we determine the representation type of some algebras of infinite matrices continuously controlled at infinity by a compact metrizable space. We explicitly classify their finitely presented modules in the finite and tame cases. The algebra of row-column-finite (or locally finite) matrices over an arbitrary field is one of the algebras considered in this paper, its representation type is shown to be finite.Comment: 33 page

Thickness dependence of exchange coupling in epitaxial Fe 3 O 4/ CoFe 2 O 4 soft/hard magnetic bilayers

Epitaxial magnetic heterostructures of (soft-)Fe3O4/(hard-)CoFe2O4(001) have been fabricated with a varying thicknesses of soft ferrite from 5 to 25 nm. We report a change in the regime of magnetic interaction between the layers from rigid-coupling to exchange-spring behavior, above a critical thickness of the soft magnetic Fe3O4 layer. We show that the symmetry and epitaxial matching between the spinel structures of CoFe2O4 and Fe3O4 at the interface stabilize the Verwey transition close to the bulk value even for 5-nm-thick Fe3O4. The large interface exchange-coupling constant estimated from low-temperature M(H) data confirmed the good quality of the ferrite-ferrite interface and the major role played by the interface in the magnetization dynamics. The results presented here constitute a model system for understanding the magnetic behavior of interfaces in core/shell nanoparticles and magnetic oxide-based spintronic devices.Fil: Lavorato, Gabriel Carlos. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; ArgentinaFil: Winkler, Elin Lilian. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; ArgentinaFil: Rivas Murias, B.. Universidad de Santiago de Compostela. Facultad de Química; EspañaFil: Rivadulla, F.. Universidad de Santiago de Compostela. Facultad de Química; Españ

A importância da sincronia visual-tátil para a manutenção da ilusão de propriedade corporal em ambientes de realidade virtual

Trabalho de conclusão de curso (graduação)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Ciência da Computação, 2021.O mercado de realidade virtual e seus usos vem crescendo muito nos últimos anos. O acesso a um dispositivo dessa tecnologia está se tornando bastante acessível e, portanto, garantir uma boa experiência nos ambientes de realidade virtual é de interesse tanto da indústria como da comunidade científica. Nesse contexto, o estudo sobre a ilusão de propriedade corporal em ambientes virtuais, independente do seu propósito, tem se tornado cada vez mais relevante. A análise dos fatores que influenciam a resiliência dessa ilusão é uma tarefa que deve ser realizada minuciosamente até que se encontre um limiar aceitável e confiável. Assim, esse trabalho estuda dois tipos de quebra da expectativa, ou assincronias, de estímulos visual-táteis com o objetivo de compreender melhor o ponto de interrupção da ilusão. Para essa compreensão, voluntários foram convidados a participar de um experimento em realidade virtual. Inicialmente, elaborou- se um ambiente virtual de modo que garanta a ilusão para os voluntários do experimento. Em seguida, foram inseridos algumas assincronias visual-táteis ao longo da experiência. A maioria dos voluntários não reportaram uma interrupção da ilusão nos pontos em que houveram as quebras de expectativa. Ao final da análise dos dados coletados, notou-se que a resiliência da ilusão é maior do que se imaginava e é resistente a quebras de expectativa ao ponto de se conjecturar que acontece um descarte ou racionalização alternativa do que está se experienciando para lidar com a discrepância entre os estímulos sensoriais recebidos e os estímulos sensoriais esperados.Virtual Reality technology, and its uses, has seen a great growth in the latest years. Access to this tech is also becoming even cheaper and easier. Therefore, guaranteeing a good experience in virtual reality is of interest to both industry and the scientific community. Because of that, there has been an increase in interest about understanding the body ownership illusion. Thus, analysis of the factors that plays a role in its resilience is a task that demands careful work until a reliable and trustworthy threshold is found. This research evaluates two types of visual-tactile breaches of expectations, or, visual-tactile asynchronies. This is done to better understand the limits of the illusion. First, a virtual environment was designed to induce the volunteers into the illusion in such a way that it is guaranteed. Following that, some visual-tactile asynchronies were inserted throughout the experiment. The majority of volunteers did not report any interruption of the illusion where it was expected to happen, i.e., where asynchronies were purposefully added in a try to break the illusion. Analyzing the collected data, it was possible to conclude that the body ownership illusion is stronger than anticipated. It is so strong, in fact, that it is conjectured that there is some sort of alternative rationalization happening in the volunteers’ mind to make sense of the mismatches between the expected sensory inputs and the actual ones. Or, at least, something similar to this effect