Single particles accelerate final stages of capillary break up

Droplet formation of suspensions is present in many industrial and technological processes such as coating and food engineering. Whilst the finite time singularity of the minimum neck diameter in capillary break-up of simple liquids can be described by well known self-similarity solutions, the pinching of non-Brownian suspension depends in a complex way on the particle dynamics in the thinning thread. Here we focus on the very dilute regime where the filament contains only isolated beads to identify the physical mechanisms leading to the pronounced acceleration of the filament thinning observed. This accelerated regime is characterized by an asymmetric shape of the filament with an enhanced curvature that depends on the size and the spatial distribution of the particles within the capillary thread.Comment: accepted for Europhysics Letter

Observing the evaporation transition in vibro-fluidized granular matter

By shaking a sand box the grains on the top start to jump giving the picture of evaporating a sand bulk, and a gaseous transition starts at the surface granular matter (GM) bed. Moreover the mixture of the grains in the whole bed starts to move in a cooperative way which is far away from a Brownian description. In a previous work we have shown that the key element to describe the statistics of this behavior is the exclusion of volume principle, whereby the system obeys a Fermi configurational approach. Even though the experiment involves an archetypal non-equilibrium system, we succeeded in defining a global temperature, as the quantity associated to the Lagrange parameter in a maximum entropic statistical description. In fact in order to close our approach we had to generalize the equipartition theorem for dissipative systems. Therefore we postulated, found and measured a fundamental dissipative parameter, written in terms of pumping and gravitational energies, linking the configurational entropy to the collective response for the expansion of the centre of mass (c.m.) of the granular bed. Here we present a kinetic approach to describe the experimental velocity distribution function (VDF) of this non-Maxwellian gas of macroscopic Fermi-like particles (mFp). The evaporation transition occurs mainly by jumping balls governed by the excluded volume principle. Surprisingly in the whole range of low temperatures that we measured this description reveals a lattice-gas, leading to a packing factor, which is independent of the external parameters. In addition we measure the mean free path, as a function of the driving frequency, and corroborate our prediction from the present kinetic theory.Comment: 6 pages, 4 figures, submitted for publication September 1st, 200

Viscoelastic response of confined powder under large strain oscillations, characterized by its noise temperature

We report a study on granular matter with and without small additions of silicon oil, under low-frequency and large amplitude oscillatory shear strain under constant normal pressure, by running experiments with a rotational rheometer with a cup-and-plate geometry. We analysed the expansion with the Chebyshev polynomials of the orthogonal decomposition of stress–strain Lissajous–Bowditch loops. We found the onset of the strain amplitude for the yielding regime indicated a regime change from filament-like structures of grains to grain rearrangements for the dry granulate and from oscillations to the breaking and regeneration of liquid bridges for wet granulates. We have shown that this viscoelastic dynamics can be characterized by a noise temperature following Sollich et al. (Phys Rev Lett https://doi.org/10.1103/ PhysRevLett.78.2020, 1997). The analysis of the first harmonics of the Chebyshev expansion showed that the state of disorder of dry and wet granular matter in pre-yielding and yielding regimes involved ensembles of different inherent states; thus, each of them was governed by a different noise temperature. The higherorder harmonics of the Chebyshev expansion revealed a proportionality between the viscous nonlinearity and the variation in the elastic nonlinearity induced by the deformation, which shows the coupling between the elastic deformation and the viscous flow of mesoscopic-scale structures

Goicochea, Adriana (Comp.) Miradas góticas. Del miedo al horror en la narrativa argentina actual. Viedma: Etiqueta Negra, 2021. 110 pp. Disponible on-line:

En Fantasy. Literatura y subversión, Jackson recurre al concepto óptico de paraxis (de par-axis: junto al eje) para presentar la tesis central de su libro: “es un área en la que los rayos de luz parecen unirse en un punto detrás de la refracción. En esta área el objeto y la imagen parecen chocar, pero en realidad ni el objeto ni la imagen reconstituida residen ahí verdaderamente: ahí no hay nada” (Jackson, p. 17). Lo fantástico constituye así una mirada a lo real que lo ensombrece y amenaza: “Toma lo real y lo quiebra” (Ib. p. 18). Esta característica subversiva y problematizadora de la percepción constituye una de las marcas centrales de las Miradas góticas que, compiladas por Adriana Goicochea, se disponen a acechar las modulaciones de “lo gótico” en la narrativa argentina reciente

A phenomenological description of the affectionate house in the domain of memory.

We present a phenomenological essay on the affective-home seeking to describe it within the scope of autobiographical experiences that confer elevated ways of comprehension of life in the poetic domain of image, remembrance and language. We seek to represent a current tradition of phenomenology whose convergence reflects hermeneutics in which the regions of belonging and rooting participate on certain fundamental ontology of the temporality of human existence. It seems to us to be a subject the within reach of a social psychology that seeks in the examination of microhistory the poetic structure of memory that unveils the feeling of inhabiting. We are looking for that original autobiographical time of Being in which we find our relationships of belonging.Apresentamos um ensaio fenomenológico da casa-afetiva procurando descrevê-la no âmbito das vivências autobiográficas que conferem formas elevadas de compreensão da vida no domínio poético da imagem, da lembrança e da linguagem. Buscamos representar uma corrente da fenomenologia cuja convergência reflete uma hermenêutica em que as regiões de pertencimento e enraizamento participam de certa ontologia fundamental da temporalidade da existência humana. Parece-nos uma matéria ao alcance de uma psicologia social que busca no exame da microhistória a estrutura poética da memória que desvela o sentimento de um habitar. Vamos em busca desse tempo autobiográfico originário do Ser no qual encontramos nossas relações de pertencimento

Sustentabilidade: um conceito de organização social das ordens de conservação e transformação do mundo

Este estudo apresenta uma análise semântica do termo sustentabilidade, procurando identificar se seria possível extrair do seu uso estratégico um projeto social. Parte-se da hipótese de que existe uma vacuidade conceitual em seu uso, de modo que suas projeções semânticas não são suficientes para estruturá-lo como conceito organizador de processos sociais compatíveis. Sob o enfoque deste trabalho, o termo sustentabilidade se constituiria no interior da atividade psicológica imanente ao sujeito, que busca interpretar seu mundo e explicar suas ordens de conservação e transformação. O método da pesquisa envolve a construção de um sistema de interpretação do termo sustentabilidade que designa forças semânticas presentes no seu emprego. Observou-se que não é possível extrair do seu uso um conceito de organização social, mas de construções teóricas transformacionistas que se impõem como necessidades lógicas com resignado apelo às referências tecnocientíficas e, ao mesmo tempo, como elemento intersubjetivo regulador de processos socioambientais não revolucionários