It has been shown that the ESS Maximum Principle, used to find evolutionarily stable strategies, is applicable to a large class of population dynamic models. These include both differential and difference equation models. To date, this principle has been used to find an evolutionarily stable strategy (ESS) for single-stage systems. That is, systems in which the density of all individuals of a given species or phenotype are represented by a scalar. There are many situations in which more detail is needed in order to properly model the state of a system (e.g. within a given species or phenotype, juveniles may effect the fitness of adults and vice versa). In this case, the density of a species or phenotype is more properly represented by a vector. Each component of the vector represents the density of a particular life stage. We show here that the ESS Maximum Principle may be extended to include multistage systems in a very natural way. In the scalar case, we have used a scalar G-function (fitness generating function) to model the system and formulate the ESS Maximum Principle. We have shown that it is necessary for the G-function, when evaluated at equilibrium, to take on a maximum with respect to the ESS strategy. Here we show, for multistage systems that a G-matrix may be used to model the system and the ESS Maximum Principle may be stated in terms of a G-matrix. In this case the real part of the dominant eigenvalue of the G-matrix, when evaluated at equilibrium, must take on a maximum with respect to the ESS strategy. Two multistage examples are given to illustrate use of the theory.
The use of Quantrad Sensor's ScoutTM in field type applications is described. The portability of the ScoutTM enables the user to obtain more accurate information in the field versus a survey meter. Isotopic identification is possible
when ancillary information is combined with built-in software libraries. Data from the ScoutTM in remediation at Stanford Linear Accelerator (SLAC), NORM (Naturally Occurring Radioactive Maerial) measurements in California's
Central Valley oil fields, medical isotope identification at nuclear pharmaceutical company and emergency response applications
are presented. Additionally, custom software enabled the use of the ScoutTM in identification, qualification and detection of Special Nuclear Materials (SNM) in illicit trafficking and portal monitoring
The thermal behaviour of Ba[Cu(C2O4)2(H2O)]·5H2O in N2 and in O2 has been examined using thermogravimetry (TG) and differential scanning calorimetry (DSC). The dehydration starts at relatively
low temperatures (about 80°C), but continues until the onset of the decomposition (about 280°C). The decomposition takes place
in two major stages (onsets 280 and 390°C). The mass of the intermediate after the first stage corresponded to the formation
of barium oxalate and copper metal and, after the second stage, to the formation of barium carbonate and copper metal. The
enthalpy for the dehydration was found to be 311±30 kJ mol−1 (or 52±5 kJ (mol of H2O)−1). The overall enthalpy change for the decomposition of Ba[Cu(C2O4)2] in N2 was estimated from the combined area of the peaks of the DSC curve as −347 kJ mol−1. The kinetics of the thermal dehydration and decomposition were studied using isothermal TG. The dehydration was strongly
deceleratory and the α-time curves could be described by the three dimensional diffusion (D3) model. The values of the activation
energy and the pre-exponential factor for the dehydration were 125±4 kJ mol−1 and (1.38±0.08)×1015 min−1, respectively. The decomposition was complex, consisting of at least two concurrent processes. The decomposition was analysed
in terms of two overlapping deceleratory processes. One process was fast and could be described by the contracting-geometry
model withn=5. The other process was slow and could also be described by the contracting-geometry model, but withn=2.
The values ofEa andA were 206±23 kJ mol−1 and (2.2±0.5)×1019 min−1, respectively, for the fast process, and 259±37 kJ mol−1 and (6.3±1.8)×1023 min−1, respectively, for the slow process.
We investigated the neighbourhood-scale effect of weeding on native plants in Lance McCaskill Nature Reserve, Canterbury, New Zealand. The reserve is an unproductive basin of limestone debris. Originally set up to protect the Castle Hill buttercup,
, the reserve also offers protection for nationally endangered species:
. Our aim was to investigate whether removal of introduced plants increased the cover of remaining native species. We removed introduced plants, by hand, every year for 6 years from half of the plots. We used nonparametric multivariate analysis to compare overall species cover.The results suggest that weeding does benefit the native plants in this area. There was a significant difference in the mean of the overall native species cover between the weeded and the non-weeded plots. For the ten species measured, the mean area covered per square metre was higher in the weeded plots than in the non-weeded plots in most years of the study. There was considerable variation in the data and we discuss possible reasons for this.
Authors:I. Brown, R. Carpenter, E. Link, and J. Mitchell
Heavy radiohalogenated derivatives of methylene blue of potential value as possible diagnostic and endoradiotherapeutic agents for malignant melanoma, have been synthesized by both electrophilic and nucleophilic reaction routes. Thermal halogen isotope exchange in molten crown ether catalyst facilitated the rapid preparation of high specific activity radioiodinated and [211At]-astatinated derivatives; radiochemical yields were in the order of 60–79%. Radiohalogenation mediated by chloramine-T or via diazonium intermediary proved more laborious, far less efficient and inappropriately is only suited to the preparation of low specific activity product.
Authors:A. Cheng, F. Ziemba, J. Browning, and N. Szluk
Quantrad Sensor's hand-held multichannel analyzer (MCA), the ScoutTM, has evolved considerably from the initial licensing from Pacific Northwest Laboratories (operated by Battelle Memorial Institute
for the U.S. DOE). The ScoutTM has grown into a flexible MCA system with alpha-, gamma-, X-ray and neutron detection capabilities with wide ranging applications.
The development philosophy is discussed along with specific examples of design choices in areas such as manufacturability,
upgradability, probe interchangability and software user interface. Recently introduced products include: software enhancements,
additional probes, customized software and a second generation instrument, the Scout512TM, that boasts increased capabilities. Future developments are also discussed.
The effect of electrolysis on the devitrification of aluminosilicate glasses containing 2–10 wt. % Ti, V, Fe, Co and Ni was studied by DTA. In all cases the devitrification temperature is lowered under electrolysis by an amount greater than that which would be achieved by independently electrolysing or doping with the transition metal ion. The relative effect of the different transition metal ions on devitrification is explained in terms of the strengths of the respective metal-oxygen bonds and the octahedral/tetrahedral site preferences of the ions. The electrolysis mechanism is similar to that of the undoped base glass, but also includes migration of the transition metal ions to the cathode and the possibility of interaction between these species and the residual protons of the base glass.
Authors:K. Gulenchyn, R. Brown, M. Green, and J. Ash
Sixteen thyroid and 2 total body iodine scans were obtained using123I in children aged 18 to 147 months. The dose of123I was 5.5–37MBq (150–1000 μCi), based on body surface area. Since the ratio of body surface area to mass is greater in children
than in adults, this method of dose calculation results in an increased dose per kilogram in the child. Furthermore, the administered
dose must be even greater than calculated in order to shorten imaging time and prevent image degradation by patient movement.
Since thyroid imaging using99mTc-pertechnetate generally gives an equivalent amount of information, this radiopharmaceutical should remain the agent of
choice in children.
Authors:W. Li, J. Cashion, R. Pollard, and L. Brown
Treating iron-doped ZSM-5 zeolite with NO2 produced a complete change in the parameters of its 57Fe Mössbauer spectrum. The intensity of the absorption showed a dramatic decrease at 40–70 K with smooth, but anharmonic, behavior above this temperature. The results can be interpreted in terms of the modification of the iron environment to form an approximately square-well potential. This results in an asymmetric potential in which the iron becomes frozen in one region at low temperatures.