Globally Optimized Parameters for a Model of Mitotic Control in Frog Egg Extracts

DNA synthesis and nuclear division in the developing frog egg are controlled by fluctuations in the activity of M-phase promoting factor (MPF). The biochemical mechanism of MPF regulation is most easily studied in cytoplasmic extracts of frog eggs, for which careful experimental studies of the kinetics of phosphorylation and dephosphorylation of MPF and its regulators have been made. In 1998 Marlovits et al. used these data sets to estimate the kinetic rate constants in a mathematical model of the control system originally proposed by Novak and Tyson. In a recent publication, we showed that a gradient-based optimization algorithm finds a locally optimal parameter set quite close to the Marlovits estimates. In this paper, we combine global and local optimization strategies to show that the refined Marlovits parameter set, with one minor but significant modification to the Novak-Tyson equations, is the unique, best-fitting solution to the parameter estimation problem

What Makes a Better Annuity?

The wide gulf between actual and predicted annuity demand has been well documented. However, a comparable gap exists between the current and ideal annuity market. In a world with costly and limited annuity products, we investigate what types of new annuity products could improve annuity market participation and increase individual welfare. We find that participation gains are most likely for new annuity products that focus on late-life payouts which offer a large price discount relative to their financial market analogues. For example, the marginal utility from the first dollar allocated to a late-life annuity can be several times that of an immediate annuity. Our welfare analysis indicates that an individual’s current assets suggest desirable new annuity products since annuities that lower the cost of the existing consumption plan necessarily improve welfare. Finally, we consider the implications for annuity demand if new annuity products ultimately complete the annuity market. Given access to a complete market, we find all individuals only purchase annuity contracts with a significant time gap between purchase and payout. At a minimum, enough time must pass between purchase and payout to build up a mortality discount sufficient to overcome the cost of creating the contract. Since most existing annuity products, such as immediate annuities, do not have this feature, few current annuity contract configurations are likely to survive significant product innovation. Taken together, our results indicate that there is ample opportunity for innovation to spur annuity demand and improve individual welfare

P4_5 The Relativistic Ionisation Speed Limit

The paper explores a possible speed limit to be enforced on relativistic vehicles so as to not expose pedestrians to ionising electromagnetic radiation; a result of Doppler shifted light from the vehicle’s headlights. A maximum speed limit of 2.89 × 108 ms-1, 0.96 times the speed of light, was established.Â

P4_8 The Solar Escapee

The paper investigates the circumstances in which a planet with an orbital radius of 1 AU from the Sun would escape the solar system due to the force supplied by the solar radiation pressure of the Sun. It is found that Earth, while fixing the mass, would require a radius above 3.06×1026 m before it would be ejected from the solar system. Alternatively a planet with the same density and orbit as Earth, but an unfixed mass, would require a radius below 2.76×10-7 m.Â

P4_2 Using the Forks: The Energy Yield of a Lightning Bolt

Lightning may be considered as a potential energy source if the yield is comparable to other renewable energy sources. The energy yield of one strike was evaluated to be 7.5×107 J, where approximately 50 strikes produce a yield equivalent to that of an average wind turbine in a year

P4_1 Dead Sea Walking

The paper investigates the possibility of walking on the water of the Dead Sea under the assumption that salt can be added to the lake. The current salinity is not sufficient to enable a person to walk on the water. Theoretically, this feat would be achievable if the lake contained 9.71 × 1015 kg of salt. Practically, this amount of salt would not dissolve in the volume of water present in the Dead Sea

P4_9 Stealing Our Atmosphere

This paper investigates two scenarios; the first is the solar wind velocity required to compress Earth’s magnetopause to an altitude of 1500km and an unrealistic value of 1.6x108ms-1 is found. The second scenario is the time it would take the solar wind to erode all of the oxygen in the atmosphere if the Earth did not have a magnetic field and an approximate value of 1.97x109 years is calculated

P4_4 The Solar Cell Efficiency of Superman

The paper investigates how efficiently Superman must absorb energy from the Sun's emission spectrum to be able to perform flight for 8 hours at a constant altitude. A solar cell efficiency of 656000% is calculated, which seemingly disobeys the law of conservation of energy assuming the model of Superman as a solar cell is reasonable