Resilience, mental health and urban migrants: a narrative review

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The purpose of this paper is to provide a narrative review of the literature on mental health resilience and other positive mental health capacities of urban and internal migrants. The methodology for this narrative review included a search of articles published up to 2017. The abstracts were screened and relevant articles studied and discussed. Literature on the particular mental health challenges of urban migrants in India was also studied. References found in the literature relating to neuro-urbanism were also followed up to explore broader historical and conceptual contexts. Several key sources and resources for mental health resilience were identified – including familial and community networks and individual hope or optimism. Nevertheless, much of the literature tends to focus at the level of the individual person, even though ecological systems theory would suggest that mental health resilience is better understood as multi-layered i.e. relevant to, and impacted by, communities and broader societal and environmental contexts. This paper provides insight into an aspect of migrant mental health that has tended to be overlooked hitherto: the mental health resilience and positive mental health capacities of urban migrants. This is particularly relevant where professional ‘expert’ mental health provision for internal migrant communities is absent or unaffordable. Previous work has tended to focus predominantly on mental health risk factors, despite growing awareness that focusing on risk factors along can lead to an over-reliance on top-down expert-led interventions and overlook positive capacities for mental health that are sometimes possessed by individuals and their communities

A direct search conjugate directions algorithm for unconstrained minimization

A direct search algorithm for unconstrained minimization of smooth functions is described. The algorithm minimizes the function over a sequence of successively finer grids. Each grid is defined by a set of basis vectors. From time to time these basis vectors are updated to include available second derivative information by making some basis vectors mutually conjugate. Convergence to one or more stationary points is shown, and the finite termination property of conjugate direction methods on strictly convex quadratics is retained. Numerical results show that the algorithm is effective on a variety of problems including ill-conditioned problems

Historical changes in the phenology of British Odonata are related to climate

Responses of biota to climate change take a number of forms including distributional shifts, behavioural changes and life history changes. This study examined an extensive set of biological records to investigate changes in the timing of life history transitions (specifically emergence) in British Odonata between 1960 and 2004. The results show that there has been a significant, consistent advance in phenology in the taxon as a whole over the period of warming that is mediated by life history traits. British odonates significantly advanced the leading edge (first quartile date) of the flight period by a mean of 1.51 ±0.060 (SEM, n=17) days per decade or 3.08±1.16 (SEM, n=17) days per degree rise in temperature when phylogeny is controlled for. This study represents the first review of changes in odonate phenology in relation to climate change. The results suggest that the damped temperature oscillations experienced by aquatic organisms compared with terrestrial organisms are sufficient to evoke phenological responses similar to those of purely terrestrial taxa

Effect of limited precision on the BFGS quasi-Newton algorithm

Some claim that updating approximate Hessian information via the BFGS formula with a Cholesky factorisation offers greater numerical stability than the more straightforward approach of performing the update directly. Others claim that no such advantage exists and that any such improvement is probably due to early implementations of the DFP formula in conjunction with low accuracy line searches. We find no discernible advantage in choosing factorised implementations (over non-factorised implementations) of BFGS methods when approximate Hessian information is available to full machine precision. However, the type of implementation may have significant effects when approximate Hessian information is only available to limited precision. Furthermore, a conjugate directions factorisation outperforms the other methods explored (including Cholesky factorisation)

Direct search methods for nonlinearly constrained optimization using filters and frames

Abstract. A direct search method for nonlinear optimization problems with nonlinear inequality constraints is presented. A filter based approach is used, which allows infeasible starting points. The constraints are assumed to be continuously differentiable, and approximations to the constraint gradients are used. For simplicity it is assumed that the active constraint normals are linearly independent at all points of interest on the boundary of the feasible region. An infinite sequence of iterates is generated, some of which are surrounded by sets of points called bent frames. An infinite subsequence of these iterates is identified, and its convergence properties are studied by applying Clarke's non-smooth calculus to the bent frames. It is shown that each cluster point of this subsequence is a Karush-Kuhn-Tucker point of the optimization problem under mild conditions which include strict differentiability of the objective function at each cluster point. This permits the objective function to be non-smooth, infinite, or undefined away from these cluster points. When the objective function is only locally Lipschitz at these cluster points it is shown that certain directions still have interesting properties at these cluster points