A Threshold Interpretation of the Ratio-Form Contest Success Function

Ratio-form contest success functions have been widely used due to their appealing axiomatic properties. Existing microfoundational models offer additional justifications for their use in specific economic applications. I propose a new structure under which a ratio-form contest success function can be derived as a limit result using an underlying contest with multiple rounds and threshold success levels. This model generalizes the stochastic equivalence of ratio-form contest success functions and patent race games, allowing greater fl exibility in the underlying structural interpretation. I additionally formulate a spatial interpretation of the model and apply the general structure to existing models of conflict.

A Conflict Theory of Voting

Research in the behavioral psychology of voting has found that voters tend to be poorly informed, highly responsive to candidate personality, and follow a "fast and frugal" heuristic. This paper analyzes optimal candidate strategies in a two-party election in which voters are assumed to behave according to these traits. Under this assumption, candidates face a trade-off between appealing to a broader base and being overly ambiguous in their policy stances. A decrease in the cost of ambiguity within this model offers a parsimonious justification for the increase in voter independence, candidate ambiguity, and party politics that empirical studies have revealed over the last five decades. I additionally argue a decrease in the cost of ambiguity is a natural result of the primary system, campaign finance reform, and changing media environment.

Essays on the theory of conflict

This dissertation consists of two papers in the field of conflict theory. In the first paper, I offer a model of American Presidential politics in which voters utilize an information heuristic. Specifically, voters vote for the candidate who espouses their ideal policy platform. If both candidates advocate this platform, voters probabilistically choose a candidate based on a contest success function incorporating policy ambiguity and candidate personality. Using this framework, I find that the optimal level of policy overlap in any given election is based only on voters' sensitivity towards policy ambiguity. As such, the recent changes in American presidential election trends are also expected to rely on this sensitivity. In the second paper, I propose a new microeconomic structure under which a ratio-form contest success function can be derived as a limit result using an underlying contest with multiple rounds and threshold success levels. This model generalizes the stochastic equivalence of ratio-form contest success functions and patent race games, allowing greater flexibility in the underlying structural interpretation. In addition, I formulate a spatial interpretation of the model in which the effectivity functions of a contest success function are related to a player's ability to increase his precision in hitting a target. Through the use of the threshold success level, I am able to relate a given effectivity function to a precision technology having desired productive characteristics

TRPC channels function independently of STIM1 and Orai1

Recent studies have defined roles for STIM1 and Orai1 as calcium sensor and calcium channel, respectively, for Ca2+-release activated Ca2+ (CRAC) channels, channels underlying store-operated Ca2+ entry (SOCE). In addition, these proteins have been suggested to function in signalling and constructing other channels with biophysical properties distinct from the CRAC channels. Using the human kidney cell line, HEK293, we examined the hypothesis that STIM1 can interact with and regulate members of a family of non-selective cation channels (TRPC) which have been suggested to also function in SOCE pathways under certain conditions. Our data reveal no role for either STIM1 or Orai1 in signalling of TRPC channels. Specifically, Ca2+ entry seen after carbachol treatment in cells transiently expressing TRPC1, TRPC3, TRPC5 or TRPC6 was not enhanced by the co-expression of STIM1. Further, knockdown of STIM1 in cells expressing TRPC5 did not reduce TRPC5 activity, in contrast to one published report. We previously reported in stable TRPC7 cells a Ca2+ entry which was dependent on TRPC7 and appeared store-operated. However, we show here that this TRPC7-mediated entry was also not dependent on either STIM1 or Orai1, as determined by RNA interference (RNAi) and expression of a constitutively active mutant of STIM1. Further, we determined that this entry was not actually store-operated, but instead TRPC7 activity which appears to be regulated by SERCA. Importantly, endogenous TRPC activity was also not regulated by STIM1. In vascular smooth muscle cells, arginine-vasopressin (AVP) activated non-selective cation currents associated with TRPC6 activity were not affected by RNAi knockdown of STIM1, while SOCE was largely inhibited. Finally, disruption of lipid rafts significantly attenuated TRPC3 activity, while having no effect on STIM1 localization or the development of ICRAC. Also, STIM1 punctae were found to localize in regions distinct from lipid rafts. This suggests that TRPC signalling and STIM1/Orai1 signalling occur in distinct plasma membrane domains. Thus, TRPC channels appear to be activated by mechanisms dependent on phospholipase C which do not involve the Ca2+ sensor, STIM1

Structure and fragmentation of growling grass frog metapopulations

Metapopulations occur in fragmented landscapes, and consist of demographically-independent populations connected by dispersal. Nevertheless, anthropogenic habitat fragmentation may be fatal to metapopulations, as it disrupts dispersal and gene flow, and undermines the balance between population extinction and colonization. Understanding the extent to which particular land-use practices disrupt dispersal and gene flow is therefore crucial for conserving metapopulations. We examined the structure and fragmentation of metapopulations of the endangered growling grass frog (Litoria raniformis) in an urbanizing landscape in southern Australia. Population clustering analyses revealed three distinct genetic units, corresponding to the three wetland clusters sampled. Isolation-by-distance was apparent between populations, and genetic distance was significantly correlated with the presence of urban barriers between populations. Our study provides evidence that urbanization fragments metapopulations of L. raniformis. Managers of L. raniformis in urbanizing landscapes should seek to mitigate effects of urbanization on dispersal and gene flow.Joshua M. Hale, Geoffrey W. Heard, Katie L. Smith, Kirsten M. Parris, Jeremy J. Austin, Michael Kearney, Jane Melvill