We use the Hamilton-Jacobi (H-J) formulation of stochastic inflation to describe the evolution of the inflaton during a period of Ultra-Slow Roll (USR), taking into account the field's velocity and its gravitational backreaction. We demonstrate how this formalism allows one to modify existing slow-roll (SR) formulae to be fully valid outside of the SR regime. We then compute the mass fraction, β, of Primordial Black Holes (PBHs) formed by a plateau in the inflationary potential. By fully accounting for the inflaton velocity as it enters the plateau, we find that PBHs are generically overproduced before the inflaton's velocity reaches zero, ruling out a period of free diffusion or even stochastic noise domination on the inflaton dynamics. We also examine a local inflection point and similarly conclude that PBHs are overproduced before entering a quantum diffusion dominated regime. We therefore surmise that the evolution of the inflaton is always predominantly classical with diffusion effects always subdominant. Both the plateau and the inflection point are characterized by a very sharp transition between the under- and over-production regimes. This can be seen either as severe fine-tunning on the inflationary production of PBHs, or as a very strong link between the fraction β and the shape of the potential and the plateau's extent.

We apply the functional Renormalisation Group (fRG) to study relaxation in a stochastic process governed by an overdamped Langevin equation with one degree of freedom, exploiting the connection with supersymmetric quantum mechanics in imaginary time. After reviewing the functional integral formulation of the system and its underlying symmetries, including the resulting Ward-Takahashi identities for arbitrary initial conditions, we compute the effective action Γ from the fRG, approximated in terms of the leading and subleading terms in the gradient expansion: the Local Potential Approximation and Wavefunction Renormalisation respectively. This is achieved by coarse-graining the thermal fluctuations in time resulting in e.g. an effective potential incorporating fluctuations at all timescales. We then use the resulting effective equations of motion to describe the decay of the covariance, and the relaxation of the average position and variance towards their equilibrium values at different temperatures. We use as examples a simple polynomial potential, an unequal Lennard-Jones type potential and a more complex potential with multiple trapping wells and barriers. We find that these are all handled well, with the accuracy of the approximations improving as the relaxation's spectral representation shifts to lower eigenvalues, in line with expectations about the validity of the gradient expansion. The spectral representation's range also correlates with temperature, leading to the conclusion that the gradient expansion works better for higher temperatures than lower ones. This work demonstrates the ability of the fRG to expedite the computation of statistical objects in otherwise long-timescale simulations, acting as a first step to more complicated systems.

Host membranes are inherently critical for niche homeostasis of vacuolar pathogens. Thus, intracellular bacteria frequently encode the capacity to regulate host lipogenesis as well as to modulate the lipid composition of host membranes. One membrane component that is often subverted by vacuolar bacteria is cholesterol – an abundant lipid that mammalian cells produce de novo at the endoplasmic reticulum (ER) or acquire exogenously from serum-derived lipoprotein carriers. Legionella pneumophila is an accidental human bacterial pathogen that infects and replicates within alveolar macrophages causing a severe atypical pneumonia known as Legionnaires’ disease. From within a unique ER-derived vacuole L. pneumophila promotes host lipogenesis and experimental evidence indicates that cholesterol production might be one facet of this response. Here we investigated the link between cellular cholesterol and L. pneumophila intracellular replication and discovered that disruption of cholesterol biosynthesis or cholesterol trafficking lowered bacterial replication in infected cells. These growth defects were rescued by addition of exogenous cholesterol. Conversely, bacterial growth within cholesterol-leaden macrophages was enhanced. Importantly, the growth benefit of cholesterol was observed strictly in cellular infections and L. pneumophila growth kinetics in axenic cultures did not change in the presence of cholesterol. Microscopy analyses indicate that cholesterol regulates a step in L. pneumophila intracellular lifecycle that occurs after bacteria begin to replicate within an established intracellular niche. Collectively, we provide experimental evidence that cellular cholesterol promotes L. pneumophila replication within a membrane bound organelle in infected macrophages.

Disasters experienced by a community place all members at risk for physical and psychological harm. While natural resilience may help many to recover, there may be barriers that hinder the recovery process. This qualitative study was conducted to examine barriers to recovery in a community impacted by both war and the tsunami. A group of 43 ethnically diverse Sri Lankans (F = 63%) participated in six focus groups and provided their perspectives on barriers they perceived to impede their recovery from traumatic events. Grounded-theory-based data analysis revealed culture-general and culture-specific socio-economic, environmental, sociocultural, and individual barriers that participants identified as impeding their recovery. Interventions and health policies targeting these groups could focus on helping communities to overcome these barriers as a means of facilitating recovery in these beleaguered communities.

Here we numerically solve the equations derived in part I of this two-part series and verify their validity. In particular we use the functional Renormalisation Group (fRG) flow equations to obtain effective potentials for initially highly anharmonic and non-polynomial potentials, including potentials with multiple trapping wells and barriers, and at different temperatures. The numerical computations determining the effective action are much faster than the direct simulation of the stochastic dynamics to which we compare our fRG results. We benchmark our numerical solutions to the flow equations by comparing the first two equilibrium cumulants from the fRG against the Boltzmann distribution. We obtain excellent agreement between the two methods demonstrating that numerical solutions for the effective potential can be accurately obtained in all the highly unharmonic cases we examined. We then assess the utility of the effective potential to describe the equilibrium 2-point correlation function x(0)x(t) and the relevant correlation time. We find that when Wavefunction Renormalisation is also utilized, these are obtained to percent accuracy for temperatures down to the typical height of the potentials' barriers but accuracy is quickly lost for lower temperatures. We also show how the fRG can offer strong agreement with direct numerical simulation of the nonequilibrium evolution of average position and variance. Also, the fRG solution represents the whole ensemble average, further adding to its convenience over other techniques, such as direct numerical simulations or solving the Fokker-Planck diffusion equation, which require multiple solutions with different initial conditions to construct averages over an ensemble.