TRA-957: LONDON ON BIKES – LONDON’S CYCLING MASTER PLAN STRATEGIC CHANGES TO IMPROVE LONDON’S CYCLING CULTURE & INFRASTRUCTURE

The City of London, Canada has been implementing cycling infrastructure since the 1980s. The City’s formal cycling master planning efforts to improve the cycling culture within the City were successfully “launched” in 2005 with the development and adoption of the City’s first Cycling Master Plan. The first master plan was followed by a strategic implementation plan which was completed in 2007 and used to guide planning, design and engineering efforts by City staff. The completion and adoption of both of these plans has led to the development of comprehensive off-road network of cycling facilities along the City’s premier Thames River Valley and an initial on-road network

Ab initio study on the magneto-structural properties of MnAs

The magnetic and structural properties of MnAs are studied with ab initio methods, and by mapping total energies onto a Heisenberg model. The stability of the different phases is found to depend mainly on the volume and on the amount of magnetic order, confirming previous experimental findings and phenomenological models. It is generally found that for large lattice constants the ferromagnetic state is favored, whereas for small lattice constants different antiferromagnetic states can be stabilized. In the ferromagnetic state the structure with minimal energy is always hexagonal, whereas it becomes orthorhombically distorted if there is an antiferromagnetic component in the hexagonal plane. For the paramagnetic state the stable cell is found to be orthorhombic up to a critical lattice constant of about 3.7 Angstrom, above which it remains hexagonal. This leads to the second order structural phase transition between paramagnetic states at about 400 K, where the lattice parameter increases above this critical value with rising temperature due to the thermal expansion. For the paramagnetic state an analytic approximation for the magnitude of the orthorhombic distortion as a function of the lattice constant is given. Within the mean field approximation the dependence of the Curie temperature on the volume and on the orthorhombic distortion is calculated. For orthorhombically distorted cells the Curie temperature is much smaller than for hexagonal cells. This is mainly due to the fact that some of the exchange coupling constants in the hexagonal plane become negative for distorted cells. With these results a description of the susceptibility as function of temperature is given

Shear-melting of a hexagonal columnar crystal by proliferation of dislocations

A hexagonal columnar crystal undergoes a shear-melting transition above a critical shear rate or stress. We combine the analysis of the shear-thinning regime below the melting with that of synchrotron X-ray scattering data under shear and propose the melting to be due to a proliferation of dislocations, whose density is determined by both techniques to vary as a power law of the shear rate with a 2/3 exponent, as expected for a creep model of crystalline solids. Moreover, our data suggest the existence under shear of a line hexatic phase, between the columnar crystal and the liquid phase

Structure and Strength of Dislocation Junctions: An Atomic Level Analysis

The quasicontinuum method is used to simulate three-dimensional Lomer-Cottrell junctions both in the absence and in the presence of an applied stress. The simulations show that this type of junction is destroyed by an unzipping mechanism in which the dislocations that form the junction are gradually pulled apart along the junction segment. The calculated critical stress needed for breaking the junction is comparable to that predicted by line tension models. The simulations also demonstrate a strong influence of the initial dislocation line directions on the breaking mechanism, an effect that is neglected in the macroscopic treatment of the hardening effect of junctions.Comment: 4 pages, 3 figure

Finite Sized Atomistic Simulations of Screw Dislocations

The interaction of screw dislocations with an applied stress is studied using atomistic simulations in conjunction with a continuum treatment of the role played by the far field boundary condition. A finite cell of atoms is used to consider the response of dislocations to an applied stress and this introduces an additional force on the dislocation due to the presence of the boundary. Continuum mechanics is used to calculate the boundary force which is subsequently accounted for in the equilibrium condition for the dislocation. Using this formulation, the lattice resistance curve and the associated Peierls stress are calculated for screw dislocations in several close packed metals. As a concrete example of the boundary force method, we compute the bow out of a pinned screw dislocation; the line-tension of the dislocation is calculated from the results of the atomistic simulations using a variational principle that explicitly accounts for the boundary force.Comment: LaTex, 20 pages, 11 figure

Ab Initio Study of Screw Dislocations in Mo and Ta: A new picture of plasticity in bcc transition metals

We report the first ab initio density-functional study of screw dislocations cores in the bcc transition metals Mo and Ta. Our results suggest a new picture of bcc plasticity with symmetric and compact dislocation cores, contrary to the presently accepted picture based on continuum and interatomic potentials. Core energy scales in this new picture are in much better agreement with the Peierls energy barriers to dislocation motion suggested by experiments.Comment: 3 figures, 3 table

Exploring the theories, determinants and policy-options of street vending: a demand-side approach

Street vending has been a common feature of urban centres for several decades, with a relatively high proportion of developing countries’ populations depending on it for employment, income or survival. Taking a supply-side approach, studies have shown that urban planners’ responses to street vending have followed the modernism theory. In this paper, we take a demand-side (buyer-focused) approach to studying street vending, which to date has received little attention from the academic community. Employing data from Lagos state, Nigeria, we report four explanations underpinning the demand-side of street vending: formal economy failures, social/redistributive, financial gains, and multifeature. These are, in turn, explained by individuals’ marital status, level of education, and perception. Our findings highlight the need for urban planners to embrace pragmatic policies in addressing these demand-side drivers of street vending and use of urban space, rather than criminalising its actors

DUNDRUM-2: Prospective validation of a structured professional judgment instrument assessing priority for admission from the waiting list for a forensic mental health hospital

<p>Abstract</p> <p>Background</p> <p>The criteria for deciding who should be admitted first from a waiting list to a forensic secure hospital are not necessarily the same as those for assessing need. Criteria were drafted qualitatively and tested in a prospective 'real life' observational study over a 6-month period.</p> <p>Methods</p> <p>A researcher rated all those presented at the weekly referrals meeting using the DUNDRUM-1 triage security scale and the DUNDRUM-2 triage urgency scale. The key outcome measure was whether or not the individual was admitted.</p> <p>Results</p> <p>Inter-rater reliability and internal consistency for the DUNDRUM-2 were acceptable. The DUNDRUM-1 triage security score and the DUNDRUM-2 triage urgency score correlated r = 0.663. At the time of admission, after a mean of 23.9 (SD35.9) days on the waiting list, those admitted had higher scores on the DUNDRUM-2 triage urgency scale than those not admitted, with no significant difference between locations (remand or sentenced prisoners, less secure hospitals) at the time of admission. Those admitted also had higher DUNDRUM-1 triage security scores. At baseline the receiver operating characteristic area under the curve for a combined score was the best predictor of admission while at the time of admission the DUNDRUM-2 triage urgency score had the largest AUC (0.912, 95% CI 0.838 to 0.986).</p> <p>Conclusions</p> <p>The triage urgency items and scale add predictive power to the decision to admit. This is particularly true in maintaining equitability between those referred from different locations.</p

New Bending Algorithm for Field-Driven Molecular Dynamics

A field-driven bending method is introduced in this paper according to the coordinate transformation between straight and curved coordinates. This novel method can incorporate with the periodic boundary conditions in analysis along axial, bending, and transverse directions. For the case of small bending, the bending strain can be compatible with the beam theory. Consequently, it can be regarded as a generalized SLLOD algorithm. In this work, the bulk copper beam under bending is analyzed first by the novel bending method. The bending stress estimated here is well consistent to the results predicted by the beam theory. Moreover, a hollow nanowire is also analyzed. The zigzag traces of atomic stress and the corresponding 422 common neighbor type can be observed near the inner surface of the hollow nanowire, which values are increased with an increase of time. It can be seen that the novel bending method with periodic boundary condition along axial direction can provide a more physical significance than the traditional method with fixed boundary condition