Buckling of imperfect cylinders under axial compression

Donnell equations, Newton method, and numerical solution applied to buckling of imperfect cylinders under axial compressio

3-manifolds with(out) metrics of nonpositive curvature

In the context of Thurstons geometrisation program we address the question which compact aspherical 3-manifolds admit Riemannian metrics of nonpositive curvature. We show that non-geometric Haken manifolds generically, but not always, admit such metrics. More precisely, we prove that a Haken manifold with, possibly empty, boundary of zero Euler characteristic admits metrics of nonpositive curvature if the boundary is non-empty or if at least one atoroidal component occurs in its canonical topological decomposition. Our arguments are based on Thurstons Hyperbolisation Theorem. We give examples of closed graph-manifolds with linear gluing graph and arbitrarily many Seifert components which do not admit metrics of nonpositive curvature.Comment: 16 page

The Great Big Doorstep Program

Program for the play Great Big Doorstep from New Rochelle College in 1944.https://digitalcommons.usm.maine.edu/giguere-early-life-and-education/1077/thumbnail.jp

A Note on Real Tunneling Geometries

In the Hartle-Hawking ``no boundary'' approach to quantum cosmology, a real tunneling geometry is a configuration that represents a transition from a compact Riemannian spacetime to a Lorentzian universe. I complete an earlier proof that in three spacetime dimensions, such a transition is ``probable,'' in the sense that the required Riemannian geometry yields a genuine maximum of the semiclassical wave function.Comment: 5 page

The nature of emotional support and counselling provision for people with sight loss in the United Kingdom

People with sight loss in the United Kingdom are known to have lower levels of emotional wellbeing and to be at higher risk of depression. Consequently ‘having someone to talk to’ is an important priority for people with visual impairment. An on-line survey of the provision of emotional support and counselling for people affected by sight loss across the UK was undertaken. The survey was distributed widely and received 182 responses. There were more services offering ‘emotional support’, in the form of listening and information and advice giving, than offered ‘counselling’. Services were delivered by providers with differing qualifications in a variety of formats. Waiting times were fairly short and clients presented with a wide range of issues. Funding came from a range of sources, but many felt their funding was vulnerable. Conclusions have been drawn about the need for a national standardised framework for the provision of emotional support and counselling services for blind and partially sighted people in the U

Time-Resolved Ultrafast Transient Polarization Spectroscopy to Investigate Nonlinear Processes and Dynamics in Electronically Excited Molecules on the Femtosecond Time Scale

We report a novel experimental technique to investigate ultrafast dynamics in photoexcited molecules by probing the third-order nonlinear optical susceptibility. A non-colinear 3-pulse scheme is developed to probe the ultrafast dynamics of excited electronic states using the optical Kerr effect by time-resolved polarization spectroscopy. Optical heterodyne and optical homodyne detection are demonstrated to measure the third-order nonlinear optical response for the S1 excited state of liquid nitrobenzene, which is populated by 2-photon absorption of a 780 nm 35 fs excitation pulse.Comment: 12 pages, 4 figures. Changes from previous version: added panel labels to figures 3-

The Generalized Ricci Flow for 3D Manifolds with One Killing Vector

We consider 3D flow equations inspired by the renormalization group (RG) equations of string theory with a three dimensional target space. By modifying the flow equations to include a U(1) gauge field, and adding carefully chosen De Turck terms, we are able to extend recent 2D results of Bakas to the case of a 3D Riemannian metric with one Killing vector. In particular, we show that the RG flow with De Turck terms can be reduced to two equations: the continual Toda flow solved by Bakas, plus its linearizaton. We find exact solutions which flow to homogeneous but not always isotropic geometries