Harmonic moment dynamics in Laplacian growth

Harmonic moments are integrals of integer powers of z = x+iy over a domain. Here the domain is an exterior of a bubble of air growing in an oil layer between two horizontal closely spaced plates. Harmonic moments are a natural basis for such Laplacian growth phenomena because, unlike other representations, these moments linearize the zero surface tension problem (Richardson, 1972), so that all moments except the lowest one are conserved in time. For non-zero surface tension, we show that the the harmonic moments decay in time rather than exhibiting the divergences of other representations. Our laboratory observations confirm the theoretical predictions and demonstrate that an interface dynamics description in terms of harmonic moments is physically realizable and robust. In addition, by extending the theory to include surface tension, we obtain from measurements of the time evolution of the harmonic moments a value for the surface tension that is within 20% of the accepted value.Comment: 10 pages, 7 figure

Moho Depth of Northern Baja California, Mexico, From Teleseismic Receiver Functions

We estimated Moho depths from data recorded by permanent and temporary broadband seismic stations deployed in northern Baja California, Mexico, using the receiver function technique. This region is composed of two subregions of contrasting geological and topographical characteristics: The Peninsular Ranges of Baja California (PRBC), a batholith with high elevations (up to 2600 m); and the Mexicali Valley (MV) region, a sedimentary environment close to sea level. Crustal thickness derived from the P‐to‐S converted phases at 29 seismic stations were analyzed in 3 profiles: two that cross the two subregions, in ∼W‐E direction, and the third one that runs over the PRBC in a N‐S direction. For the PRBC, Moho depths vary from 35 to 45‐km, from 33ºN to 32ºN; and from 30 to 46‐km depth from 32ºN to 30.5ºN. From a profile that crosses the subregions in the W‐E direction; Moho depths vary from 45 to ∼34‐km under western and eastern PRBC, respectively; with an abrupt change of depth under the Main Gulf Escarpment (30º), from ∼32 to 30‐km; and depths of 17‐20‐km under the MV. Moho depths of the profile in an ∼W‐E direction at ∼31.5ºN from ∼30 to 40‐km, under topography that increase from 0 to 2600 m; and became shallower (16‐km depth) as the profile reaches the Gulf of California. These results show that deeper Moho is related to higher elevations with an abrupt change under the Main Gulf Escarpment, except for western PRBC were the Moho depth is not simply reflect isostatic compensation

Moho Depth of Northern Baja California, Mexico, From Teleseismic Receiver Functions

We estimated Moho depth from data recorded by permanent and temporary broadband seismic stations deployed in northern Baja California, Mexico using the receiver function technique. This region is composed, mainly, of two subregions of contrasting geological and topographical characteristics: The Peninsular Ranges of Baja California (PRBC), a batholith with high elevations (up to 2600 m above mean sea level); and the Mexicali Valley (MV) region, a sedimentary environment at around the mean sea level. Crustal thickness derived from the P-to-S converted phases at 29 seismic stations were analyzed in 3 profiles: two that cross the two subregions, in a ~W-E direction, and the third one that runs over the PRBC in a N-S direction. For the PRBC region, Moho depths vary from 35 to 45 km, from 33°;N to 32°;N; and from 30 to 46 km depth from 32°;N to 30.5°;N. From a profile that crosses the subregions in the W-E direction; Moho depths vary from 45 to ~34 km under the PRBC; with an abrupt change of depth under the Main Gulf Escarpment, from ~32 to 30 km; and depths of 17-20 km under the MV region. Moho depths of the profile that runs, of an almost W-E direction at ~31.5°; N, follow the eltimetry from 0 to 2600 m: from ~30 to 40 km; and became shallower (16 km depth) as the profile reaches the Gulf of California. These results show that deeper Moho is related to higher elevations with an abrupt change under the Main Gulf Escarpment

New Technologies’ Promise to the Self and the Becoming of the Sacred: Insights from Georges Bataille’s Concept of Transgression

This article draws on Georges Bataille’s concept of transgression, a key element in Bataille’s theory of the sacred, to highlight structural implications of the way the self-empowerment ethos of new technologies suffuses the digital tracking culture. Pointing to the original conceptual stance of transgression, worked out against prohibition, I first argue that, beyond a critique of new technologies’ promise of self-empowerment as coming at the expense of an acknowledgement of the ultimate taboo—death—is the problem of the sanitizing of the tension between the crossing of the line of the symbolic taboo and prohibition; this undermines a “libidinal investment” towards the sacred, which is central in Bataille’s theory. Second, focussing on “eroticism”, since this embodies the emancipative potential of the Bataillean sacred, I argue that while a fear of eroticism marks out the digital technological realm, this is covered up by the blurring of boundaries between pleasure, fun and sex(iness) that currently governs our experience with technological devices

Grit ingestion and size-related consumption of tubers by Graylag Geese

In herbivorous birds the processing rate of food is constrained by gizzard capacity. To enhance digestive processes, many species ingest grit to grind the food. Grit ingestion, however, may further limit the capacity of file gizzard. Graylag Geese (Anser anser) wintering in SW Spain fed mainly on Alkali Bulrush (Scirpus maritimus) tubers, showing a preference for small tubers. This preference may be due to a faster disintegration of small tubers than larger ones inside the gizzard. As larger tubers are likely coarser than smaller tubers, more grit would be necessary to process larger tubers. However, the ingestion of more grit to grind large tubers would be at the expense of ingesting additional tubers because of gizzard capacity limitations. Under these circumstances, there may be an inverse relationship between tuber size and amount of grit ingested to optimize food ingestion. Indeed, we found such a relationship. Grit facilitated the disintegration of tubers. This suggests that relying on some amount of grit to facilitate the grinding of food should outweigh the loss of gizzard capacity to the amount of food ingested.Peer Reviewe

Silver Linings at the Dawn of a ‘Golden Age'

ACKNOWLEDGMENTS We would like to thank the editors at Frontiers for their support and patience, and the careful consideration two reviewers gave to this manuscript. MJW would like to acknowledge that, at Fairbanks, he is working on the ancestral land of Troth Yeddha’, home of the Lower Tanana people. He would also like to acknowledge that the lands on which he does his work are the ancestral lands of the Dené people who stewarded those lands for thousands of years and continue to steward those lands, further he would like to thank them and respect their enduring relationship to their homelands.Peer reviewedPublisher PD