Chapter 7 Cellular Control of Time, Size, and Shape in Development and Evolution

The rules by which anatomical size and shape are generated have intrigued scientists for centuries. In 1638, Galileo suggested a mathematical relationship between proportional changes in the shape of bones as animals increase in size, which he argued was a functional necessity for weight bearing (1914). The formalism of Galileo, whereby, physical forces and mathematical laws became integrated with studies of size and shape in biology, was most conspicuously encapsulated over a hundred years ago in the 1917 monumental tome by D’Arcy Thompson entitled, On Growth and Form (Thompson 1917). In a breathtakingly comprehensive manner, Thompson synthesized the observations of numerous predecessors and contemporaries, and through countless examples built a theoretical and experimental framework for describing changes in morphology that persists to this day (Stern and Emlen 1999; Arthur 2006)

The impact of weather variability and climate change on pesticide applications in the US - An empirical investigation

Weather variability and climate change affect the application of pesticides in agriculture, in turn impacting the environment. Using panel data regression for the US, we find that weather and climate differences significantly influence the application rates of most pesticides. Subsequently, the regression results are linked to downscaled climate change scenario the Canadian and Hadley climate change models. We find that the application of most pesticides increase under both scenarios. The projection results vary by crop, region, and pesticide.Climate change, weather variability, pesticide, regression, panel data, North America, US

Economic impacts of changes in fish population dynamics: the role of the fishermen’s harvesting strategies

Using a bioeconomic model of the cod (Gadus morhua) and capelin (Mallotus villosus) fisheries of the Barents Sea, this study assesses the role of the fishermen’s behavior in reducing or intensifying the effects on the stocks caused by altered population dynamics. The analysis focuses on the economic development of the fisheries employing a profit-maximizing harvesting strategy over a given number of fishing periods. The scenarios assessed cover a time period of 100 years with sudden changes of the productivity of both species occurring at the midpoint of each simulation. Stock sizes and landings of fish are determined for each fishing period, and the net present values of profits over periods of interest prior to and following the change in population dynamics are calculated. Results show that if the profit-maximizing harvesting strategy is based on a short optimization period, the fleets with the higher efficiency are generally favored. If the strategy is based on an optimization over two or more fishing periods, fishing activities may be deferred to allow for stock regrowth. In such cases, smaller and less cost-intensive vessels are preferred. A reduction of either the productivity or the carrying capacities of the two species has little impact on the fisheries if the change is fairly small. A substantial reduction of either quantity has a lasting negative economic impact which mainly manifests itself in a severely reduced profitability of mainly the cod fishery.bioeconomic modeling, Barents Sea, cod, capelin, population dynamics, harvesting strategy

Rebuilding the Eastern Baltic cod stock under environmental change - a preliminary approach using stock, environmental, and management constraints

The population dynamics of the Eastern Baltic cod (Gadus morhua callarias L.), unlike many other stocks, shows a strong dependency on environmental conditions. To test the implications of different management policies on the stock and the fishery in a system of global environmental change, we apply a spatially disaggregated, discrete time, age-structured model of the Eastern Baltic cod stock in 50 year simulation analyses. The simulation provides an analysis of stock, yield, and revenue development under various management policies and environmental scenarios. The policy analysis, focusing on different regulations of fishing mortality, is embedded into three environmental scenarios, assuming low, medium, or high climate and environmental change. The environmental assumptions are based on simulation results from a coupled atmosphere-ocean regional climate model, which project salinity in the Baltic Sea to decrease by 7-47% in the period 2071-2100 relative to the reference period 1961-1990. Our simulation results show that a significant reduction in fishing mortality is necessary for achieving high long-term economic yields. Moreover, under the presented environmental scenarios, a stock collapse cannot be prevented. It can, however, be postponed by the establishment of a marine reserve in ICES subdivision 25.Baltic cod, climate change, environmental variability, reproductive volume, population dynamics, management, policy, age-structured model, temporal marine reserve

Rebuilding the Eastern Baltic cod stock under environmental change - Part II: The economic viability of a marine protected area

This study adds a cost analysis of the Eastern Baltic cod fishery to the existing model presented in Röckmann et al. (forthcoming). As cost data on this international fishery do not exist, available data from Denmark are extrapolated to the whole international fishery. Additionally, unit and total variable costs are simulated and the sensitivity to a set of different cost-stock and cost-output elasticities is tested. The study supports preliminary conclusions that a temporary marine reserve policy, which focuses on protecting the Eastern Baltic cod spawning stock in ICES subdivision 25, is a valuable fisheries management tool to (a) rebuild the overexploited Eastern Baltic cod stock and (b) increase operating profits. The negative effects of climate change can be postponed for at least 20 years – depending on the assumed rate of future climate change. Including costs in the economic analysis does not change the ranking of management policies as proposed in the previous study where costs were neglected.Development, Baltic cod, cost-stock elasticity, cost-output elasticity, sensitivity analysis, climate change scenario, management, policy, temporal marine reserve

Average-passage simulation of counter-rotating propfan propulsion systems as applied to cruise missiles

Counter-rotating propfan (CRP) propulsion technologies are currently being evaluated as cruise missile propulsion systems. The aerodynamic integration concerns associated with this application are being addressed through the computational modeling of the missile body-propfan flowfield interactions. The work described in this paper consists of a detailed analysis of the aerodynamic interactions between the control surfaces and the propfan blades through the solution of the average-passage equation system. Two baseline configurations were studied, the control fins mounted forward of the counter-rotating propeller and the control fins mounted aft of the counter-rotating propeller. In both cases, control fin-propfan separation distance and control fin deflection angle were varied

Chapter 7 Cellular Control of Time, Size, and Shape in Development and Evolution

The rules by which anatomical size and shape are generated have intrigued scientists for centuries. In 1638, Galileo suggested a mathematical relationship between proportional changes in the shape of bones as animals increase in size, which he argued was a functional necessity for weight bearing (1914). The formalism of Galileo, whereby, physical forces and mathematical laws became integrated with studies of size and shape in biology, was most conspicuously encapsulated over a hundred years ago in the 1917 monumental tome by D’Arcy Thompson entitled, On Growth and Form (Thompson 1917). In a breathtakingly comprehensive manner, Thompson synthesized the observations of numerous predecessors and contemporaries, and through countless examples built a theoretical and experimental framework for describing changes in morphology that persists to this day (Stern and Emlen 1999; Arthur 2006)

Preface

It has been shown by Freris, Graham and Kumar that clocks in distributed networks cannot be synchronized precisely in the presence of asymmetric time delays even in idealized situations. Motivated by that impossibility result, we test under similar settings the performance of some existing clock synchronization protocols and show that the synchronization errors between neighboring nodes can be bounded within an acceptable level of accuracy that is determined by the degree of asymmetry in time delays. After studying the basic case of synchronizing two clocks in the two-way message passing process, we first analyze the directed ring networks, in which neighboring clocks are likely to experience severe asymmetric time delays. We then discuss connected undirected networks with two-way message passing between each pair of adjacent nodes. In the end, we expand the discussions to networks with directed topologies that are strongly connected

Testing the implications of a permanent or seasonal marine reserve on the population dynamics of Eastern Baltic cod under varying environmental conditions

In order to test the implications of the establishment of a marine reserve in the Baltic Sea, a spatially disaggregated, discrete time, age-structured model for the Eastern Baltic cod (Gadus morhua callarias L.) stock was constructed. Functional relationships for recruitment and predation mortality were developed by multiple regression analyses. The resultant model output compares well with observed data from the fishery. The model was then applied to simulate stock development over a 50 year time period using different management policies and a variety of environmental conditions. The investigated management policies reduce fishing mortality and range from a moratorium on the Eastern Baltic cod fishery via the establishment of a permanent or a seasonal marine reserve in ICES subdivision 25 to a fishing as usual scenario. The environmental conditions incorporated were based on the size of the reproductive volume (RV) and comprise a best case and a worst case of reproductive conditions, and two more realistic scenarios, where we assumed that a historic series of RV-sizes reoccurs over the simulation period. Our results show a strong dependence of stock dynamics on the environmental conditions. Under prevailing low RV, our model projects stock extinction by the year 2020, if fishing continues as usual. Under the restrictive scenarios, where fishing mortality is reduced either directly or by implementation of a marine reserve, the stock benefits from an increase in stock size and an improved age-structure. A seasonal closure of SD 25 as opposed to a closure of the entire Baltic Sea appears to be sufficient to prevent the Eastern Baltic cod stock from falling below safe biological limits.Baltic cod, management, age-structured model, population dynamics, MPA, environmental variability, reproductive volume