Wake Vortex Pair Formation as an Analog for Dust Devil and Tornado Genesis

In 1966, meteorologist R.S. Scorer attempted to explain how large-scale oceanic tropical depressions become hurricanes or typhoons. His model was based on the idea that when these large-scale tropical depression structures begin to rotate, mostly due to Coriolis effects, an annular outer portion of that structure changes suddenly to a potential vortex segment, with the same outer radial limit as the low-pressure structure, but with an inner radius that conserves the overall system angular momentum and kinetic energy. By analogy with the jump instability describing sudden buckling of a vertical column, this paper shows that his conjecture merits additional consideration. If valid, the Scorer model implies that the controlling large scale flow is essentially an inviscid Rankine vortex. While hurricanes can sustain this Rankine vortex eye structure over warm ocean, over land smaller-scale tornadoes and dust devils cannot draw from a similar sustaining energy source. Scorer\u27s model implies that, without additional energy, the outer inviscid vortex region should force the rotating inner cylindrical region to collapse as the overall inviscid structure proceeds toward the rotational axis. That vortex evolution requires additional energy- from an unknown source. This paper utilizes Scorer\u27s finite vortex domain hypothesis on an evolving aircraft wake vortex pair, and his assertion that the inviscid vortex pair is the controlling flow, to generate turbulent non-equilibrium vortex cores and by extension explain how tornadoes and dust devils form from rotating atmosphere

Rho GTPase function in flies: insights from a developmental and organismal perspective.

Morphogenesis is a key event in the development of a multicellular organism and is reliant on coordinated transcriptional and signal transduction events. To establish the segmented body plan that underlies much of metazoan development, individual cells and groups of cells must respond to exogenous signals with complex movements and shape changes. One class of proteins that plays a pivotal role in the interpretation of extracellular cues into cellular behavior is the Rho family of small GTPases. These molecular switches are essential components of a growing number of signaling pathways, many of which regulate actin cytoskeletal remodeling. Much of our understanding of Rho biology has come from work done in cell culture. More recently, the fruit fly Drosophila melanogaster has emerged as an excellent genetic system for the study of these proteins in a developmental and organismal context. Studies in flies have greatly enhanced our understanding of pathways involving Rho GTPases and their roles in development

Wnt signalling and cancer stem cells

[Abstract] Intracellular signalling mediated by secreted Wnt proteins is essential for the establishment of cell fates and proper tissue patterning during embryo development and for the regulation of tissue homeostasis and stem cell function in adult tissues. Aberrant activation of Wnt signalling pathways has been directly linked to the genesis of different tumours. Here, the components and molecular mechanisms implicated in the transduction of Wnt signal, along with important results supporting a central role for this signalling pathway in stem cell function regulation and carcinogenesis will be briefly reviewed.Ministerio de Ciencia e Innovación; SAF2008-0060

The role of geochemical baselines in the assessment of land quality

In the light of recent European and UK government legislation there is a need to identify and quantify the potential hazard of contaminated land. Previous attempts to define ‘safe levels’ of Potentially Harmful Elements and Species (PHES) have proved to be less than satisfactory. For example, when the Council of European Communities (CEC) guideline for nickel was applied to regional geochemical baseline data in Finland, extensive areas of the north-west of the country were designated as contaminated it spite of their being little evidence of harm to the indigenous population or environment. In the UK, many areas containing high concentrations (i.e. above the Inter-governmental Committee on Redevelopment of Contaminated Land trigger values) of PHES have been identified. There is a clear role for geochemical baselines in assessing and revising these guidelines, and in the assessment of their potential economic impact