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Two forces are necessary and sufficient to produce the transformation of the newt neural plate from a hemispheric sheet of cells one cell thick to a keyhole shape. These forces are: (1) a regionally programmed shrinkage of the surface of the neural plate (accomplished by contraction of the apical surfaces of the neural plate cells and elongation of these(More)
Is sovereign borrowing so different from corporate debt that there is no need for bankruptcy-style procedures to protect debtors? With the waiver of immunity, sovereign debtors who already face severe disruption from short-term creditors grabbing their currency reserves are also exposed to litigious creditors trying to seize what assets they can in a 'race(More)
We have discovered a series of expansion and contraction, solitary waves that correlate with discrete steps of differentiation in the urodele amphibian axolotl embryo (Ambystoma mexicanum). Here we examine in detail the proposition that the blastopore is a set of differentiation waves. We superimposed the image of the axolotl fate map onto our digitized(More)
In the face of increasing CO 2 emissions from conventional energy (gasoline), and the anticipated scarcity of crude oil, a worldwide effort is underway for cost-effective renewable alternative energy sources. Here, we review a simple line of reasoning: (a) geologists claim that much crude oil comes from diatoms; (b) diatoms do indeed make oil; (c)(More)
Zealand Ministry for the Environment. All copyright is the property of the Crown. This information may be copied and distributed to others without limitation, provided that the Ministry for the Environment and the providers of the information are acknowledged. Under no circumstances may a charge be made for this information without the express permission of(More)
The visually impaired have limited access to the world of mobile devices. Our goal was to design a handheld mobile device to overcome limitations such as reliance on visual display and lack of audio and tactile feedback. We built a prototype handheld device using a combination of tactile feedback and auditory display based on preliminary research and(More)
Although therapeutic treatment strategies appear promising for retarding the progression of HIV-related diseases, prevention remains the most effective strategy against the HIV/AIDS epidemic. This paper focuses on the effect of condom use as a single-strategy approach in HIV prevention in the absence of any treatment. There are two primary factors in the(More)
BACKGROUND There has been a sudden increase in the amount of money donors are willing to spend on the worldwide HIV/AIDS epidemic. Present plans are to hold most of the money in reserve and spend it slowly. However, rapid spending may be the best strategy for halting this disease. METHODS We develop a mathematical model that predicts eradication or(More)
Evolution on rugged landscapes ceases when a local maximum is attained. This poses the problem of how evolution could approach or attain a global maximum, especially for large genomes for which quasispecies are ineffective. I show how increasing the dimensionality of the landscape, which occurs every time there is a gene or higher order duplication (up to(More)