Emotion regulation capacity in older adults: Effects on facial expression and memory

This thesis primarily investigated the extent to which the capacity for emotion regulation is preserved in older adults. In doing this, the current research explored possible contributors that might help explain how older adults regulate their emotions as well as young adults, and the limitations to emotion regulation ability in ageing. Subtle changes in muscle activity associated with positive and negative facial expressions were measured with zygomaticus and corrugator facial electromyography (EMG) as a novel technique to determine age differences in specific emotion regulation use, as well as age differences in emotional reactivity

Missing Shapiro steps and the 8π8\pi-periodic Josephson effect in interacting helical electron systems

Two-particle backscattering in time-reversal invariant interacting helical electron systems can lead to the formation of quasiparticles with charge $e/2$. We propose a way to detect such states by means of the Josephson effect in the presence of proximity-induced superconductivity. In this case, the existence of $e/2$ charges leads to an $8 \pi$-periodic component of the Josephson current which can be identified through measurement of Shapiro steps in Josephson junctions. In particular, we show that even when there is weak explicit time-reversal symmetry breaking, which causes the two-particle backscattering to be a sub-leading effect at low energies, its presence can still be detected in driven, current-biased Shapiro step measurements. The disappearance of some of these steps as a function of the drive frequency is directly related to the existence of non-Abelian zero-energy states. We suggest that this effect can be measured in current state-of-the-art Rashba wires.Comment: 9 pages, 5 figures. A new submission extending and expanding our analysis in arXiv:1507.08881. (v2) References adde

Electronic spin-triplet nematic with a twist

We analyze a model of itinerant electrons interacting through a quadrupole density-density repulsion in three dimensions. At the mean field level, the interaction drives a continuous Pomeranchuk instability towards $d$-wave, spin-triplet nematic order, which simultaneously breaks the SU(2) spin-rotation and spatial rotational symmetries. This order results in spin antisymmetric, elliptical deformations of the Fermi surfaces of up and down spins. We show that the effects of quantum fluctuations are similar to those in metallic ferromagnets, rendering the nematic transition first-order at low temperatures. Using the fermionic quantum order-by-disorder approach to self-consistently calculate fluctuations around possible modulated states, we show that the first-order transition is pre-empted by the formation of a nematic state that is intertwined with a helical modulation in spin space. Such a state is closely related to $d$-wave bond density wave order in square-lattice systems. Moreover, we show that it may coexist with a modulated, $p$-wave superconducting state.Comment: 15 pages, 9 figure

The Geometric Phase and Gravitational Precession of D-Branes

We study Berry's phase in the D0-D4-brane system. When a D0-brane moves in the background of D4-branes, the first excited states undergo a holonomy described by a non-Abelian Berry connection. At weak coupling this is an SU(2) connection over R^5, known as the Yang monopole. At strong coupling, the holonomy is recast as the classical gravitational precession of a spinning particle. The Berry connection is the spin connection of the near-horizon limit of the D4-branes, which is a continuous deformation of the Yang and anti-Yang monopole.Comment: 23 pages; v3: typos correcte

Identifying as in, out, or sexually inexperienced: Perception of sex-related personal disclosures

The current research explored perceptions of disclosing the information of "I am gay", "I am heterosexual", and "I am a virgin" to a variety of audiences. Participants were 842 undergraduate students who evaluated the valence of each disclosure, listed the associated feelings, and rated the comfort of disclosing such information to various audiences (e.g., a family member, online community). Participants rated the statement consistent with their own sexual orientation as being significantly more positive. No significant difference was found between gay and heterosexual participants’ ratings about disclosing virginity, and disclosure of virginity status was ranked as the most uncomfortable of the three disclosures. Both heterosexual and gay respondents indicated it would be more comfortable to disclose a heterosexual orientation than a gay one, despite gay participants rating a gay orientation as more positive. The audience ranked most to least comfortable to disclose varied with sexual orientation and disclosure content. Perceived closeness of audience was correlated with comfort of disclosure for known (family, partner, friend, colleague) audiences, but not professional (counsellor) or unknown (stranger, online) audiences. These findings are discussed with reference to the literature on “coming out”, addressing important differences in the perceptions of in-group and out-group disclosure of sexual orientation, and sex-related personal information

The Geometric Phase in Supersymmetric Quantum Mechanics

We explore the geometric phase in N=(2,2) supersymmetric quantum mechanics. The Witten index ensures the existence of degenerate ground states, resulting in a non-Abelian Berry connection. We exhibit a non-renormalization theorem which prohibits the connection from receiving perturbative corrections. However, we show that it does receive corrections from BPS instantons. We compute the one-instanton contribution to the Berry connection for the massive CP^1 sigma-model as the potential is varied. This system has two ground states and the associated Berry connection is the smooth SU(2) 't Hooft-Polyakov monopole.Comment: 28 pages, 2 figures, references added. v2: clarification of possible corrections to Abelian Berry phase. v3: footnotes added to point the reader towards later development