Ancient Greek Hydromyths About the Submarine Transport of Terrestrial Fresh Water Through Seabeds Offshore of Karstic Regions

This study examined the relationship between ancient Greek texts and the physical possibility of focused, distal flow of terrestrial fresh water through the seabed, particularly offshore of karstic coasts. The four ancient texts which were analyzed describe powerful discharges from submarine springs in the eastern Black Sea; the local transport of groundwater through the bed of Turkey’s Bay of Miletus; alleged subterranean–submarine connections between coastal western Turkey and the Greek northeast Peloponnese; and alleged connections between the coastal western Peloponnese and southeastern coastal Sicily. The plausibility or implausibility of these legends was assessed in the context of modern reports indicating that seabed pathways can transport continental fresh water up to 60 km offshore. Other reports identify fresh water in the seabed as far as 160 km offshore, presumably due to marine-induced forces. These documented cases validated ancient claims of nearshore groundwater transport and legitimized transoceanic claims as mythologized extrapolations of local karstic hydrogeology. As submarine fresh groundwater becomes increasingly important in understanding material transport and in identifying potentially exploitable coastal water supplies, ancient stories from past civilizations may give clues to offshore sites meriting further exploration

Karst Hydrology in Ancient Myths from Arcadia and Argolis, Greece

The history of karst science includes ancient Greek literary narratives that describe the behavior of karstic waters, yet remain largely unrecognized for their hydrogeological relevance. This paper integrates karst hydrology with ancient myths and travelogues describing natural features in Arcadia and Argolis of the Greek Peloponnese. The karstic landscapes of these two regions were figuratively represented in the interrelated myths of the Danaids, Poseidon, and Amymone. In a nonmythical report of a historical occurrence, a deer hunter chased a deer into the temporarily flooded polje of ancient Stymphalus, but a sudden dislodging of the sinkhole debris plug caused the lake to drain so rapidly that the hunter and his prey were suctioned helplessly down into the whirlpool. Other ancient narratives described the subterranean connection of the Stymphalian polje and the Argolic springs of Erasinus. Some accounts stemmed from an ancient religious practice of throwing items into waters to propitiate the water gods: In one case, the watery disposition of propitiatory wreaths was determined by interweavings of the surface and subsurface components of the two karstic rivers named Alpheus and Eurotas. In other ancient accounts, certain rivers were said to sink underground at the coastline, travel through the bed of a bay or sea, and resurge as subaerial freshwater springs on the opposite shore of the saline waterbody

Antitrust - Restraint of Trade - Group Boycott - NFL College Draft

The United States District Court for the District of Columbia has held that the National Football League\u27s annual college draft is a concerted refusal to deal amounting to a group boycott, and is thus a per se violation of section 1 of the Sherman Act. Smith v. Pro-Football, 420 F. Supp. 738 (D.D.C. 1976)

A study of after-images, influences of the after-image on memory and perception

Thesis (M.A.)--University of Kansas, Psychology, 1932

The effects of refractive index heterogeneity within kidney tissue on multiphoton fluorescence excitation microscopy

Although multiphoton fluorescence excitation microscopy has improved the depth at which useful fluorescence images can be collected in biological tissues, the reach of multiphoton fluorescence excitation microscopy is nonetheless limited by tissue scattering and spherical aberration. Scattering can be reduced in fixed samples by mounting in a medium whose refractive index closely matches that of the fixed material. Using optical 'clearing', the effects of refractive index heterogeneity on signal attenuation with depth are investigated. Quantitative measurements show that by mounting kidney tissue in a high refractive index medium, less than 50% of signal attenuates in 100 μm of depth

Deep Tissue Fluorescent Imaging in Scattering Specimens Using Confocal Microscopy

In scattering specimens, multiphoton excitation and nondescanned detection improve imaging depth by a factor of 2 or more over confocal microscopy; however, imaging depth is still limited by scattering. We applied the concept of clearing to deep tissue imaging of highly scattering specimens. Clearing is a remarkably effective approach to improving image quality at depth using either confocal or multiphoton microscopy. Tissue clearing appears to eliminate the need for multiphoton excitation for deep tissue imaging

A mechanical model of early somite segmentation

Somitogenesis is often described using the clock-and-wavefront (CW) model, which does not explain how molecular signaling rearranges the pre-somitic mesoderm (PSM) cells into somites. Our scanning electron microscopy analysis of chicken embryos reveals a caudally-progressing epithelialization front in the dorsal PSM that precedes somite formation. Signs of apical constriction and tissue segmentation appear in this layer 3-4 somite lengths caudal to the last-formed somite. We propose a mechanical instability model in which a steady increase of apical contractility leads to periodic failure of adhesion junctions within the dorsal PSM and positions the future inter-somite boundaries. This model produces spatially periodic segments whose size depends on the speed of the activation front of contraction (F), and the buildup rate of contractility (Λ). The Λ/F ratio determines whether this mechanism produces spatially and temporally regular or irregular segments, and whether segment size increases with the front speed

The effects of spherical aberration on multiphoton fluorescence excitation microscopy

Multiphoton fluorescence excitation microscopy is almost invariably conducted with samples whose refractive index differ from that of the objective immersion medium, conditions that cause spherical aberration. Due to the quadratic nature of multiphoton fluorescence excitation, spherical aberration is expected to profoundly affect the depth dependence of fluorescence excitation. In order to determine the effect of refractive index mismatch in multiphoton fluorescence excitation microscopy, we measured signal attenuation, photobleaching rates and resolution degradation with depth in homogeneous samples with minimal light scattering and absorption over a range of refractive indices. These studies demonstrate that signal levels and resolution both rapidly decline with depth into refractive index mismatched samples. Analyses of photobleaching rates indicate that the preponderance of signal attenuation with depth results from decreased rates of fluorescence excitation, even in a system with a descanned emission collection pathway. Similar results were obtained in analyses of fluorescence microspheres embedded in rat kidney tissue, demonstrating that spherical aberration is an important limiting factor in multiphoton fluorescence excitation microscopy of biological samples

Cadherin-4 plays a role in the development of zebrafish cranial ganglia and lateral line system

We previously reported that cadherin-4 (also called R-cadherin) was expressed by the majority of the developing zebrafish cranial and lateral line ganglia. Cadherin-4 (Cdh4) function in the formation of these structures in zebrafish was studied using morpholino antisense technology. Differentiation of the cranial and lateral line ganglia and lateral line nerve and neuromasts of the cdh4 morphants was analyzed using multiple neural markers. We found that a subset of the morphant cranial and lateral line ganglia were disorganized, smaller, with reduced staining, and/or with altered shape compared to control embryos. Increased cell death in the morphant ganglia likely contributed to these defects. Moreover, cdh4 morphants had shorter lateral line nerves and a reduced number of neuromasts, which was likely caused by disrupted migration of the lateral line primordia. These results indicate that Cdh4 plays a role in the normal formation of the zebrafish lateral line system and a subset of the cranial ganglia. Developmental Dynamics 236:893–902, 2007. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55963/1/21085_ftp.pd

Virtual-tissue computer simulations define the roles of cell adhesion and proliferation in the onset of kidney cystic disease

In autosomal dominant polycystic kidney disease (ADPKD), cysts accumulate and progressively impair renal function. Mutations in PKD1 and PKD2 genes are causally linked to ADPKD, but how these mutations drive cell behaviors that underlie ADPKD pathogenesis is unknown. Human ADPKD cysts frequently express cadherin-8 (cad8), and expression of cad8 ectopically in vitro suffices to initiate cystogenesis. To explore cell behavioral mechanisms of cad8-driven cyst initiation, we developed a virtual-tissue computer model. Our simulations predicted that either reduced cell-cell adhesion or reduced contact inhibition of proliferation triggers cyst induction. To reproduce the full range of cyst morphologies observed in vivo, changes in both cell adhesion and proliferation are required. However, only loss-of-adhesion simulations produced morphologies matching in vitro cad8-induced cysts. Conversely, the saccular cysts described by others arise predominantly by decreased contact inhibition, that is, increased proliferation. In vitro experiments confirmed that cell-cell adhesion was reduced and proliferation was increased by ectopic cad8 expression. We conclude that adhesion loss due to cadherin type switching in ADPKD suffices to drive cystogenesis. Thus, control of cadherin type switching provides a new target for therapeutic intervention