Doctor of Philosophy

dissertationVocalizations are used in multiple contexts for widely different functions. However, the vocalizing individual may convey more information than merely the primary context of the vocalization, including caller identity, dominance status, reproductive status, body condition, etc. Decoding these potential signals could be useful as a noninvasive research tool in conservation. We explore this possibility in the long-distance vocalization of the male orangutan, the long call, and address three questions. When do males call? Researchers must first understand the temporal call patterns of the targeted species to know when and how to study the species. By using a passive acoustic monitoring (PAM) system and direct observation, we were able to study in an unbiased manner when flanged male orangutans call. We discovered that the diurnal orangutan calls more frequently at night than during the activity period. What influences the calling behavior of individuals? Understanding if social or environmental factors influence vocal behavior is necessary to be able to disentangle the information content of vocal signals. While multiple social factors, like association with another individual, do result in a higher long call rate of male orangutans, the dominant influence on vocal behavior was food availability. We discuss how local ecology may determine to which degree each factor can influence vocal behavior. How do vocalizations vary over time? Understanding which aspects of the vocalization remain constant and which vary is key to understanding which acoustic features may encode signals that should not change, such as identity, and signals that may change, such as body condition or dominance status. We found that, while there is inter-individual variation, overall the orangutan long call is not stereotyped, and the most easily measured acoustic features do not allow reliable identification of individuals over long time periods. With current rates of deforestation around the world, conservation managers seek a less labor intensive and noninvasive method to monitor habitat condition. If researchers are able to decode acoustic signals, vocal behavior may provide a more sensitive method to monitor populations and, potentially, habitat condition. This research shows for the highly endangered orangutan clear limitations in this approach, but also highlights that habitat condition may be reflected in the calling behavior

Platforms, portfolios, policy : how audience costs affect social welfare policy in multiparty cabinets

When and why do electoral commitments enhance parties’ ability to implement their preferred policy in multiparty governments? We propose an audience costs theory whereby strong platform commitments enhance parties’ negotiating positions in multiparty cabinets but only when they are on a salient policy issue for core voters and the party controls the policy-relevant portfolio. Utilizing new data on portfolio allocations in eight parliamentary democracies over 40 years, we show that absent a strong platform commitment, control of the portfolio of social affairs by social democrats, alone, is not associated with changes in welfare generosity. Notably, our findings are independent of party size and hold in most multiparty legislative systems not dominated by three parties

Approximate solutions and micro-regularity in the Denjoy–Carleman classes

AbstractWe begin with a sequence M of positive real numbers and we consider the Denjoy–Carleman class CM. We show how to construct M-approximate solutions for complex vector fields with CM coefficients. We then use our construction to study micro-local properties of boundary values of approximate solutions in general M-involutive structures of codimension one, where the approximate solution is defined in a wedge whose edge (where the boundary value exists) is a maximally real submanifold. We also obtain a CM version of the Edge-of-the-Wedge Theorem

Locally solvable vector fields and Hardy spaces

AbstractWe characterize the boundary value of homegeneous solutions of planar one-sided locally solvable vector fields with analytic coefficients with the property that the Lp norm of their traces is locally uniformly bounded, 0<p⩽1. For p≠1/n, n=1,2,…, the boundary value must locally belong to the local Hardy space hp(R) of Goldberg while for p=1/n, n=1,2,…, the answer calls for a new class of atomic Hardy spaces if the vector field is of infinite type at some boundary point