28,523 research outputs found
Influences of environmental and biological factors on song complexity in songbirds : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Auckland, New Zealand
Content removed due to copyright reasons: Hill, S. D., Pawley, M. D. M., Anderson, M. G., & Weihong, J. (2017). Higher song complexity and intruder pressure at dawn in a vocally complex songbird. Emu - Austral Ornithology, 118(2), 147-157. doi:10.1080/01584197.2017.1380503In songbirds, song is important for mate attraction and territory defence. Females of
some species preferentially select males that have more complex songs, an honest
signal for male fitness. Examining variation in song complexity provides important
insights into the evolution of sexually-selected vocal characteristics. In this thesis,
hypotheses examining song complexity variation and a series of biological and
environmental factors were tested. A socially monogamous songbird with highly
complex songs and high extra-pair paternity (tui, Prosthemadera novaeseelandiae)
was selected as the main study model. Firstly, the hypothesis that song complexity in
songbird broadcast songs would be higher than in interactive songs was tested. In
addition, it was predicted that there would be a positive association between song
complexity and extra-pair paternity frequency. This was conducted across 78
songbird species, the most comprehensive analysis in this study area to date.
Concordant with the predictions, tui broadcast songs were found to have higher
complexity than interactive songs. Furthermore, after controlling for phylogenetic
relatedness, a significant positive association between extra-pair paternity frequency
and within-song complexity was found across multiple species. Secondly, I tested
the hypothesis that tui song complexity would be higher at dawn than at solar noon
and dusk. It has previously been established that dawn is a critical period for
intensified songbird vocal displays, such as increased song rate. However, little
research has been conducted on diurnal variations in song complexity, which was
predicted to be higher at dawn. As predicted, both tui song complexity and intrusion
rates were significantly greater at dawn than at dusk. In addition, two song
complexity variables were inversely correlated with intrusion rate. Thirdly, the
hypothesis that male tui would respond more aggressively to more complex songs
was tested, to assess whether song complexity plays a role in male-male interactions.
Male responses to rival male songs of different degrees of complexity were
subsequently examined using playback experiments. Male tui songs with higher
complexity evoked stronger and more aggressive intrasexual responses than simple
song as predicted. Fourthly, I tested the hypothesis that habitat complexity would
correlate positively with tui song complexity. The association between habitat
structure and tui song complexity was investigated by comparing male song
complexity in two types of habitat: forest remnants with high complexity, and open
habitats with lower complexity. As predicted, habitat complexity correlated
positively with tui song complexity. Overall, the findings in this thesis provide
evidence that several biological and environmental factors are associated with the
evolution of song complexity; a socially-selected vocal trait. This study suggests that
complex songs in vocally complex songbirds may have evolved under extra-pair
paternity, territorial and environmental pressures. It therefore has implications for
furthering our understanding of song complexity evolution in songbirds
Cartan Invariants of Symmetric Groups and Iwahori-Hecke Algebras
K\"{u}lshammer, Olsson and Robinson conjectured that a certain set of numbers
determined the invariant factors of the -Cartan matrix for
(equivalently, the invariant factors of the Cartan matrix for the Iwahori-Hecke
algebra , where is a primitive th root of unity).
We call these invariant factors Cartan invariants.
In a previous paper, the second author calculated these Cartan invariants
when , prime, and and went on to conjecture that the
formulae should hold for all . Another result was obtained, which is
surprising and counterintuitive from a block theoretic point of view. Namely,
given the prime decomposition , the Cartan matrix
of an -block of is a product of Cartan matrices associated to
-blocks of . In particular, the invariant factors of the Cartan
matrix associated to an -block of can be recovered from the Cartan
matrices associated to the -blocks.
In this paper, we formulate an explicit combinatorial determination of the
Cartan invariants of --not only for the full Cartan matrix, \emph{but for
an individual block}. We collect evidence for this conjecture, by showing that
the formulae predict the correct determinant of the -Cartan matrix. We
then go on to show that Hill's conjecture implies the conjecture of KOR
Poverty and Deprivation in Dumfries and Galloway: A Spatial Approach
This study was commissioned and funded by Dumfries and Galloway Council to provide evidence and analysis of the nature and patterns of poverty and deprivation across the region. It complements the Dumfries and Galloway Regional Economic Strategy Baseline Study and Regional Economic Profile published in 2014 and the four Area Profiles published earlier in the year (2015), and has been used to inform the development of the regionâs first Anti-Poverty Strategy. It is consistent with best practice in policy development by providing quantitative data, drawn from national and local sources and qualitative information, and qualitative data drawn from Discussion Groups with people experiencing poverty across the region. The findings will be used to inform Elected Members, officers and partners throughout the implementation of the Anti-Strategy over the coming five years and also in its final evaluation
P-adic interpolation of metaplectic forms of cohomological type
Let G be a reductive algebraic group over a number field k. It is shown how
Emerton's methods may be applied to the problem of p-adically interpolating the
metaplectic forms on G, i.e. the automorphic forms on metaplectic covers of G,
as long as the metaplectic covers involved split at the infinite places of k.Comment: 37 page
The Khovanov-Lauda 2-category and categorifications of a level two quantum sl(n) representation
We construct 2-functors from a 2-category categorifying quantum sl(n) to
2-categories categorifying the irreducible representation of highest weight $ 2
\omega_k.
Quantum supergroups V. Braid group action
We construct a braid group action on quantum covering groups. We further use
this action to construct a PBW basis for the positive half in finite type which
is pairwise-orthogonal under the inner product. This braid group action is
induced by operators on the integrable modules; however, these operators
satisfy spin braid relations.Comment: v1. 31 pages v2. minor revisions, updated references, to appear in
CM
Market feedback, investment constraints, and managerial behavior
This paper examines the joint role of market feedback and investment constraints on managerial behavior. Using a sample of UK fixed price initial public offerings, we show that underperformance of share returns at the IPO significantly affects managerial investment decisions in the period after the offering. Firms with better investment opportunities and proportionately lower fixed (higher intangible) assets are more sensitive to negative market feedback. Over the longer term, the more responsive firms perform significantly better than their non-responsive counterparts. The findings contribute to the debate on the informational advantage of managers over investors and present strong evidence that the market, on aggregate, can provide a superior assessment of a firm's opportunities. Managers who are able to respond to negative market feedback can significantly improve their firm's future prospects
A cyclo-stationary complex multichannel wiener filter for the prediction of wind speed and direction
This paper develops a linear predictor for application to wind speed and direction forecasting in time and across different sites. The wind speed and direction are modelled via the magnitude and phase of a complex-valued time-series. A multichannel adaptive filter is set to predict this signal, based on its past values and the spatio-temporal correlation between wind signals measured at numerous geographical locations. The time-varying nature of the underlying system and the annual cycle of seasons motivates the development of a cyclo-stationary Wiener filter, which is tested on hourly mean wind speed and direction data from 13 weather stations across the UK, and shown to provide an improvement over both stationary Wiener filtering and a recent auto-regressive approach
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