Sublimation-driven morphogenesis of Zen stones on ice surfaces

In this article, the formation of Zen stones on frozen lakes and the shape of the resulting pedestal are elucidated. Zen stones are natural structures in which a stone, initially resting on an ice surface, ends up balanced atop a narrow ice pedestal. We provide a physical explanation for their formation, sometimes believed to be caused by the melting of the ice. Instead, we show that slow surface sublimation is indeed the physical mechanism responsible for the differential ablation. Far from the stone, the sublimation rate is governed by the diffuse sunlight, while in its vicinity, the shade it creates inhibits the sublimation process. We reproduced the phenomenon in laboratory-scale experiments conducted in a lyophilizer and studied the dynamics of the morphogenesis. In this apparatus, which imposes controlled constant sublimation rate, a variety of model stones consisting of metal disks was used, which allows us to rule out the possible influence of the thermal conduction in the morphogenesis process. Instead, we show that the stone only acts as an umbrella whose shade hinders the sublimation, hence protecting the ice underneath, which leads to the formation of the pedestal. Numerical simulations, in which the local ablation rate of the surface depends solely on the visible portion of the sky, allow us to study the influence of the shape of the stone on the formation of the ice foot. Finally, we show that the far-infrared black-body irradiance of the stone itself leads to the formation of a depression surrounding the pedestal.

Slow surface diffusion on Cu substrates in Li metal batteries

Dendrite growth on the lithium metal anode still obstructs a widespread commercialization of high energy density lithium metal batteries. In this work, we investigate how the crystal structure of the...

SLOW SURFACE ELECTROMAGNETIC WAVES AT THE METASURFACE / DISSIPATIVE DIELECTRIC INTERFACE

The possibilities of the slow surface electromagnetic waves propagation along the flat boundary of a metasurface with a dissipative dielectric are studied. The metasurface is a thin flat slab of metamaterial with simultaneously negative permittivity and permeability with "amplification". All media were assumed to be isotropic. Dispersion dependences are obtained for the eigenmodes of such a waveguide structure. The possibility of full compensation of the energy losses of surface waves by the appropriate choice of the “gains” values is demonstrated.

Reading

“Reading” is one of the most provocative terms in literary theory, in part because it connotes both an activity and a product: on the one hand, an effort to comprehend a text or object of knowledge, and on the other, a more formal response. Both senses of the term originate in the premise that literary and other cultural texts—including performances, scripted or not—require a more deliberative parsing than weather reports and recipes, or sentences like “rain is expected today” and “add one cup of flour.” At the same time, reading serves as an explanatory trope across various sites of 21st-century culture; in a tennis match, players “read” the strengths and weaknesses of their opponents and strategize accordingly; a cab driver “reads” a GPS when plotting an efficient route to convey a passenger. But an engagement with literary and cultural texts is a different matter. In its former sense as a set of protocols or procedures, reading resides at the center of disciplinary debates as newly formed schools, theories, or methods rise to challenge dominant notions of understanding literature, film, painting, and other forms. Frequently, these debates focus on tensions between binary oppositions (real or presumed): casual versus professional reading (or fast vs. slow), surface reading versus symptomatic reading, close reading versus distant reading, and others. Like the term “reading,” readers are variously described as “informed,” “ideal,” “implied,” and more. In some theoretical formulations, they are anticipated by texts; in others, readers produce or complete them by filling lacunae or conducting other tasks. Complicating matters further, reading also exists in close proximity to several other terms with which it is often associated: interpretation, criticism, and critique. Issues of “textuality” introduce yet another factor in disagreements about the priorities of critical reading, as notions of a relatively autonomous or closed work or object have been supplanted by a focus on both historical context and a work’s “intertextuality,” or its inevitable relationship to, even quotation of, other texts. In the latter sense of a reading as an intellectual or scholarly product, more variables inform definitions. Every reading of a text, as Paul Ricouer describes, “takes place within a community, a tradition, or a living current of thought.” The term “reading” is complicated not only because of the thing studied but also because of both the historically grounded human subject undertaking the activity and the disciplinary expectations shaping and delimiting the interpretations they produce. And, in the 21st century, technologies and practices have emerged to revise these conversations, including machine learning, computational modeling, and digital textuality.

Обратная волна Ценнека вдоль плоской границы раздела сред

We consider the surface Zennek wave along the plane boundaries of the vacuum-medium interface with isotropic permittivity, and the vacuum-medium described by isotropic dielectric and magnetic permittivity. In the latter case, we also consider the H-wave and the possibility of negative real parts of the permeability. Forward and backward waves at the boundary of a material with an inhomogeneous permittivity profile are considered. The conditions for the existence of forward and backward surface and volume waves, as well as fast and slow surface waves, are studied.