Bifurcation of periodic solutions to the singular Yamabe problem on spheres

We obtain uncountably many periodic solutions to the singular Yamabe problem on a round sphere, that blow up along a great circle. These are (complete) constant scalar curvature metrics on the complement of $S^1$ inside $S^m$, $m\geq 5$, that are conformal to the round (incomplete) metric and "periodic" in the sense of being invariant under a discrete group of conformal transformations. These solutions come from bifurcating branches of constant scalar curvature metrics on compact quotients of $S^m \setminus S^1\cong S^{m-2}\times H^2$.Comment: LaTeX2e, 12 pages, final version. To appear in J. Differential Geo

The nonequilibrium Ehrenfest gas: a chaotic model with flat obstacles?

It is known that the non-equilibrium version of the Lorentz gas (a billiard with dispersing obstacles, electric field and Gaussian thermostat) is hyperbolic if the field is small. Differently the hyperbolicity of the non-equilibrium Ehrenfest gas constitutes an open problem, since its obstacles are rhombi and the techniques so far developed rely on the dispersing nature of the obstacles. We have developed analytical and numerical investigations which support the idea that this model of transport of matter has both chaotic (positive Lyapunov exponent) and non-chaotic steady states with a quite peculiar sensitive dependence on the field and on the geometry, not observed before. The associated transport behaviour is correspondingly highly irregular, with features whose understanding is of both theoretical and technological interest

Uniformly bounded representations and completely bounded multipliers of SL(2,R)

We estimate the norms of many matrix coefficients of irreducible uniformly bounded representations of SL(2, R) as completely bounded multipliers of the Fourier algebra. Our results suggest that the known inequality relating the uniformly bounded norm of a representation and the completely bounded norm of its coefficients may not be optimal

Visual observation to identify sexes in subspecies of adult Black Skimmers (Rynchops niger)

Identifying sexes in birds from visual observations could be a useful and inexpensive method. While sexual dichromatism and ornaments are readily used by observers, sexual size dimorphism can also be used to identify sexes in some bird species. This study assessed the applicability of visual observation of size differences to identify sexes in adult Black Skimmers (Rynchops niger). Black Skimmers do not have sexual dichromatism; however, Black Skimmer males are skeletally larger (6.7–31.7% depending on trait) and 33.3–37.5% heavier than females. The study focused on two subspecies: Amazonian (R. n. cinerascens) and South American (R. n. intercedens) Black Skimmers. Sex identified by visually observing size differences was consistent with the sex identified at specimen preparation from examining gonads (RGLMM = 0.996 ± 0.004). The identification of sexes from photographs using visual observation of size had a very high within- (RGLMM = 0.995 ± 0.001) and between- (RGLMM = 0.984 ± 0.002) observer repeatability. Non-invasive methods for identifying sex by visual observation may allow enhanced use of data from photographic datasets, citizen science projects, and surveys using direct observation or images

Using field photography to study avian moult

Methods to obtain moult data from wild birds have not changed much over the last century and most studies still depend on checking museum specimens or capturing birds. Here we assess the applicability of systematic field photography for detecting and scoring moult in adult Black Skimmers Rynchops niger from southern Brazil. Moult data extracted from photographs have a high within- (RGLMM = 0.98) and between-observer repeatability (RGLMM = 0.97) and show very good fit to current Underhill–Zucchini moult models (R2 = 0.75). Photography offers the advantages of being less invasive, requiring less equipment and human effort, being feasible in areas where captures may not be possible, and causing less disturbance, so enhancing the number of sampled individuals

Analysis of Spattering Activity at Halemaumau in 2015.

M.S. Thesis. University of Hawaiʻi at Mānoa 2017

What does it take to help an outgroup?

The present thesis has focused on helping behaviour towards disadvantaged outgroups. Research was done at an intergroup level, and obtained its theoretical foundation from the Social Identity theory (Tajfel & Turner, 1986), self-categorization theory (Turner, 1985; Turner et al., 1987) and the empathy-altruism model (Batson, 1987, 1991; Batson et al., 1989; Batson & Shaw, 1991) and focused on the influence of identity content and ingroup norms in investigating outgroup helping. Experiments were carried out concerning different instances that could affect outgroup helping and were centred around social identity and identity content, accountability, intragroup power and empathy towards the outgroup. The first two studies focused on the role of particular identities in terms of the Social identity theory (Tajfel & Turner, 1986). In experiment 1 it was found that people regulate their empathy towards beggars by their non-salient religious identity when they are together with others. The presence of others such as friends and partner, who are aware of the participant‘s religious identity, could possibly evoke accountability concerns, which are then reflected in empathy and prosocial behaviour towards a disadvantaged group. In experiment 2 a salient political identity only led to pro-social behavioural preferences and empathy towards beggars for those with left-wing identities; as opposed to those with a right wing preference. Concluding, the content of ideologically-defined identities (religious, political) served to regulate empathy and prosocial behaviour, but the salience of these identities could play a crucial mediating role in certain contexts. The plausible effect of accountability was further investigated in experiments 3 and 3a. Unfortunately no conclusive results were found. Experiments 4 and 5 investigated the role of intragroup power on outgroup helping. Results showed that people with high intragroup power either affect the prosocial behaviour of people that are less certain of their political preference compared to people who are certain of their political preference, possibly due to processes in accordance with the social comparison theory (Festinger, 1954) and intragroup differentiation (experiment 4), or were found to be less prosocial towards an outgroup (experiment 5) than people with lower intragroup power. Finally in experiment 6 and 7, research was directed towards intergroup awareness and empathy. Experiment 6 demonstrated that an outgroup will be perceived with more empathy and prosocial behaviour when awareness of the outgroup is high than when awareness of the outgroup is low. In experiment 7, people high in empathy towards a disadvantaged outgroup were more willing to allocate money to the outgroup than people lower in empathy. Overall, the results of the experiments in the subsequent chapters led to believe that ingroup identity and content, and ingroup norms are feasible with regard to helping a certain disadvantaged outgroup. These findings fit with the theories of social identity and self categorization, given that feeling and behaving according to ingroup norms is the objective, and suggesting that people each have a variety of different identities, which become activated in different social contexts. Furthermore inducing empathy towards an outgroup seemed to be an useful tool to promote helping behaviour towards an outgroup