Delayed response of a fermion-pair condensate to a modulation of the interaction strength

The effect of a sinusoidal modulation of the interaction strength on a fermion-pair condensate is analytically studied. The system is described by a generalization of the coupled fermion-boson model that incorporates a time-dependent intermode coupling induced via a magnetic Feshbach resonance. Nontrivial effects are shown to emerge depending on the relative magnitude of the modulation period and the relaxation time of the condensate. Specifically, a nonadiabatic modulation drives the system out of thermal equilibrium: the external field induces a variation of the quasiparticle energies, and, in turn, a disequilibrium of the associated populations. The subsequent relaxation process is studied and an analytical description of the gap dynamics is obtained. Recent experimental findings are explained: the delay observed in the response to the applied field is understood as a temperature effect linked to the condensate relaxation time.Comment: 6 page

A Computational Study of Blood Flow and Vascular Nitric Oxide Transport

Atherosclerosis occurs in a spatially heterogeneous fashion within the arterial system. The patchy nature of the disease is thought to reflect spatial variation in haemodynamic factors such as wall shear stress (WSS) and in the concentration of vascular species. This thesis numerically investigates blood flow and vascular transport of the atheroprotective agent nitric oxide (NO) using a spectral/hp element method. Firstly, NO distribution is analysed within a parallel-plate flow chamber coated with endothelial cells. Contrary to the accepted hypothesis that NO concentration increases with WSS (as does NO production), it is observed that NO concentration depends on WSS in a non-monotonic fashion. Furthermore, these results emphasise the effect of convection on in vitro NO transport, which has been overlooked or misinterpreted in most previous computational studies. Secondly, blood flow and NO transport are investigated within a detailed representation of the rabbit thoracic aorta and its branches, which was reconstructed using high resolution computed tomography (CT) scan data of a vascular corrosion cast. The computed WSS distribution exhibits significant spatial heterogeneity, reflecting the complexity of the blood flow. In particular it is observed that two Dean-type vortices (associated with a skewed velocity profile) form in the aortic arch and propagate along the descending aorta. This results in streaks of WSS similar in nature to the fatty streaks of early stage atherosclerosis observed in mature rabbits. This finding provides further support for the hypothesis that blood flow mediates atherogenesis. The vascular distribution of NO is found to depend significantly on the relationship between NO production and WSS. Furthermore, it is concluded that mechanisms preventing NO consumption by haemoglobin (such as diffusional barriers) must exist in order for NO to exert its atheroprotective action. This study represents the first effort to model NO transport in a realistic representation of the major arteries

Understanding the dependence on the pulling speed of the unfolding pathway of proteins

The dependence of the unfolding pathway of proteins on the pulling speed is investigated. This is done by introducing a simple one-dimensional chain comprising $N$ units, with different characteristic bistable free energies. These units represent either each of the modules in a modular protein or each of the intermediate "unfoldons" in a protein domain, which can be either folded or unfolded. The system is pulled by applying a force to the last unit of the chain, and the units unravel following a preferred sequence. We show that the unfolding sequence strongly depends on the pulling velocity $v_{p}$. In the simplest situation, there appears a critical pulling speed $v_{c}$: for pulling speeds $v_{p}v_{c}$ it is the pulled unit that unfolds first. By means of a perturbative expansion, we find quite an accurate expression for this critical velocity.Comment: accepted for publication in JSTA

Feynman diagrams with the effective action

A derivation is given of the Feynman rules to be used in the perturbative computation of the Green's functions of a generic quantum many-body theory when the action which is being perturbed is not necessarily quadratic. Some applications are discussed.Comment: Extended revised version. RevTex, 19 pages, 10 figure

Teachers\u27 Perspectives on Translanguaging as a Pedagogical Resource in Senior High School English Classes

Translanguaging has been documented in previous research as a pedagogical resource in language classrooms. However, the monolinguistic culture prevents the leveraging of this resource in language learning. In addition, despite the extensive research on translanguaging, its use as a pedagogical resource is limited, particularly in the Philippine context. This study explores teachers’ perspectives on translanguaging in Senior High School subjects where English is the medium of instruction. Findings from focus group discussions reveal that the participants leverage translanguaging as a resource to help students in knowledge construction, meaning-making, and problem-solving. This study concludes with implications for policymakers and language teachers who believe only English will help language learning