Intrapersonal positive future thinking predicts repeat suicide attempts in hospital-treated suicide attempters

Objective: Although there is clear evidence that low levels of positive future thinking (anticipation of positive experiences in the future) and hopelessness are associated with suicide risk, the relationship between the content of positive future thinking and suicidal behavior has yet to be investigated. This is the first study to determine whether the positive future thinking–suicide attempt relationship varies as a function of the content of the thoughts and whether positive future thinking predicts suicide attempts over time. Method: A total of 388 patients hospitalized following a suicide attempt completed a range of clinical and psychological measures (depression, hopelessness, suicidal ideation, suicidal intent and positive future thinking). Fifteen months later, a nationally linked database was used to determine who had been hospitalized again after a suicide attempt. Results: During follow-up, 25.6% of linked participants were readmitted to hospital following a suicide attempt. In univariate logistic regression analyses, previous suicide attempts, suicidal ideation, hopelessness, and depression—as well as low levels of achievement, low levels of financial positive future thoughts, and high levels of intrapersonal (thoughts about the individual and no one else) positive future thoughts predicted repeat suicide attempts. However, only previous suicide attempts, suicidal ideation, and high levels of intrapersonal positive future thinking were significant predictors in multivariate analyses. Discussion: Positive future thinking has predictive utility over time; however, the content of the thinking affects the direction and strength of the positive future thinking–suicidal behavior relationship. Future research is required to understand the mechanisms that link high levels of intrapersonal positive future thinking to suicide risk and how intrapersonal thinking should be targeted in treatment interventions

In vivo activation of Wnt/Beta-catenin signaling to model Schwann cell tumors in mice

Faculty advisor: Dr. David LargaespadaThis research was supported by the Undergraduate Research Opportunities Program (UROP)

The Singular Hydrodynamic Interactions Between Two Spheres In Stokes Flow

We study exact solutions for the slow viscous flow of an infinite liquid caused by two rigid spheres approaching each either along or parallel to their line of centres, valid at all separations. This goes beyond the applicable range of existing solutions for singular hydrodynamic interactions (HIs) which, for practical applications, are limited to the near-contact or far field region of the flow. For the normal component of the HI, by use of a bipolar coordinate system, we derive the stream function for the flow as $Re\to 0$ and a formula for the singular (squeeze) force between the spheres as an infinite series. We also obtain the asymptotic behaviour of the forces as the nondimensional separation between the spheres goes to zero and infinity, rigorously confirming and improving upon known results relevant to a widely accepted lubrication theory. Additionally, we recover the force on a sphere moving perpendicularly to a plane as a special case. For the tangential component, again by using a bipolar coordinate system, we obtain the corresponding infinite series expression of the (shear) singular force between the spheres. All results hold for retreating spheres, consistent with the reversibility of Stokes flow. We demonstrate substantial differences in numerical simulations of colloidal fluids when using the present theory compared with existing multipole methods. Furthermore, we show that the present theory preserves positive definiteness of the resistance matrix $\boldsymbol{R}$ in a number of situations in which positivity is destroyed for multipole/perturbative methods.Comment: 28 pages, 12 Figure

Analysis and applications of dynamic density functional theory

Classical fluid mechanics and, in particular, the general compressible Navier-Stokes-Fourier equations, have long been of great use in the prediction and understanding of the flow of fluids in various scenarios. While the classical theory is well established in increasingly rigorous mathematical frameworks, the atomistic properties and microscopic processes of fluids must be considered by other means. A central problem in fluid mechanics concerns capturing microscopic effects in meso/macroscopic continuum models. With more attention given to the non-Newtonian properties of many naturally occurring fluid flows, resolving the gaps between the atomistic viewpoint and the continuum approach of Navier-Stokes-Fourier is a rich and open field. This thesis centres on the modelling, analysis and computation of one continuum method designed to resolve the highly multiscale nature of non-equilibrium fluid flow on the particle scale: Dynamic Density Functional Theory (DDFT). A generalised version of DDFT is derived from first principles to include: driven flow, inertia and hydrodynamic interactions (HI) and it is observed that the equations reproduce known dynamics in heuristic overdamped and inviscid limits. Also included are rigorous, analytical derivations of the short-range lubrication forces on particles at low Reynolds number, with accompanying asymptotic theory, uniformly valid in the entire regime of particle distances and size ranges, which were previously unknown. As well as demonstrating an improvement on known classical results, these calculations were determined necessary to comply with the continuous nature of the integro-differential equations for DDFT. The numerical implementation of the driven, inertial equations with short range HI for a range of colloidal systems in confining geometries is also included by developing the pseudo-spectral collocation scheme 2DChebClass [67]. A further area of interest for non-equilibrium fluids is mathematical well–posedness. This thesis provides, for the first time, the existence and uniqueness of weak solutions to an overdamped DDFT with HI, as well as a rigorous investigation of its equilibrium behaviour

Marine bird foraging around headlands in tidal streams

HydrodynamicsAbstrac

A Comparative Analysis of Potential Spatio-Temporal Access to Palliative Care Services in Two Canadian Provinces

Background Access to health services such as palliative care is determined not only by health policy but a number of legacies linked to geography and settlement patterns. We use GIS to calculate potential spatio-temporal access to palliative care services. In addition, we combine qualitative data with spatial analysis to develop a unique mixed-methods approach. Methods Inpatient health care facilities with dedicated palliative care beds were sampled in two Canadian provinces: Newfoundland and Saskatchewan. We then calculated one-hour travel time catchments to palliative health services and extended the spatial model to integrate available beds as well as documented wait times. Results 26 facilities with dedicated palliative care beds in Newfoundland and 69 in Saskatchewan were identified. Spatial analysis of one-hour travel times and palliative beds per 100,000 population in each province showed distinctly different geographical patterns. In Saskatchewan, 96.7 % of the population living within a-1 h of drive to a designated palliative care bed. In Newfoundland, 93.2 % of the population aged 65+ were living within a-1 h of drive to a designated palliative care bed. However, when the relationship between wait time and bed availability was examined for each facility within these two provinces, the relationship was found to be weak in Newfoundland (R2 = 0.26) and virtually nonexistent in Saskatchewan (R2 = 0.01). Conclusions Our spatial analysis shows that when wait times are incorporated as a way to understand potential spatio-temporal access to dedicated palliative care beds, as opposed to spatial access alone, the picture of access changes