Static and dynamic degradation of sintered calcium phosphate ceramics

The chemical compositions of calcium phosphate materials are similar to that of bone making them very attractive for use in the repair of critical size bone defects. The bioresorption of calcium phosphate occurs principally by dissolution. To determine the impact of composition and flow conditions on dissolution rates, calcium phosphate tablets were prepared by slip casting of ceramic slips with different ratios of hydroxyapatite (HA) and ß-tricalcium phosphate (ß-TCP). Dissolution was evaluated at pH4 using both a static and dynamic flow regime. Both the composition of the HA:ß-TCP tablet and flow regime noticeably influenced the rate of dissolution; the 50:50 HA:ß-TCP composition demonstrating the greatest level of dissolution, and, exposure of the ceramic specimens to dynamic conditions producing the highest rate of dissolution. Understanding the impact of phase composition and flow condition with respect to the dissolution of calcium phosphate will aid in the development and improvement of materials for bone substitution.

Technological Learning in Developing Countries

Technological learning refers to the learning processes involved in improving the productive capabilities of an enterprise, sector or economy to enable it to produce higher quality goods or services with increasing levels of efficiency. Approaches to the study of technological learning include case studies of particular countries, sectors and firms; measures of export sophistication; and composite indicators of innovation and competitiveness. The present review draws on these approaches to provide an overview of the policies and practices that have been successful in different regions (East-Asia and Latin America) ; contexts (import substitution and liberalization) ; sectors (pulp and paper, IT services, electronics and passenger cars); and firms (Embrear and Lenovo). While it is clear that there is strong complementarity between domestic technological capability and the ability to absorb foreign technology, there is no simple policy recipe which is appropriate for all times, industries or places. Technological learning builds on and is shaped by what is already known. It requires time, space and resources all of which are influenced by the wider domestic and international context. The current international context is challenging but countries and firms have to find ways of moving forward despite the limited strategy space.

Assessment of the double-skin façade passive thermal buffer effect.

Double Skin Façades (DSFs) are becoming increasingly popular architecture for commercial office buildings. Although DSFs are widely accepted to have the capacity to offer significant passive benefits and enable low energy building performance, there remains a paucity of knowledge with regard to their operation. Identification of the most determinant architectural parameters of DSFs is the focus of ongoing research. This paper presents an experimental and simulation study of a DSF installed on a commercial building in Dublin, Ireland. The DSF is south facing and acts to buffer the building from winter heat losses, but risks enhancing over-heating on sunny days. The façade is extensively monitored during winter months. Computational Fluid Dynamic (CFD) models are used to simulate the convective operation of the DSF. This research concludes DSFs as suited for passive, low energy architecture in temperature climates such as Ireland but identifies issues requiring attention in DSF design.

Development of a Vehicle-Bridge-Soil Dynamic Interaction Model for Scour Damage Modelling

Damage detection in bridges using vibration-based methods is an area of growing research interest. Improved assessment
methodologies combined with state-of-the-art sensor technology are rapidly making these approaches applicable for real-world
structures. Applying these techniques to the detection and monitoring of scour around bridge foundations has remained
challenging; however this area has gained attraction in recent years. Several authors have investigated a range of methods but
there is still significant work required to achieve a rounded and widely applicable methodology to detect and monitor scour.This
paper presents a novel Vehicle-Bridge-Soil Dynamic Interaction (VBSDI) model which can be used to simulate the effect of scour
on an integral bridge. The model outputs dynamic signals which can be analysed to determine modal parameters and the variation
of these parameters with respect to scour can be examined.The key novelty of this model is that it is the first numerical model for
simulating scour that combines a realistic vehicle loadingmodel with a robust foundation soil responsemodel.This paper provides a
description of the model development and explains the mathematical theory underlying themodel. Finally a case study application
of the model using typical bridge, soil, and vehicle properties is provided.

Bernard Mandeville and the doctrine of laissez-faire

The view of Mandeville as a pioneer of laissez-faire is difficultto reconcile with his repeated insistence that private vices were turnedinto public benefits by the ‘dexterous management of the skilfulpolitician’. Even if references to the skilful politician are regarded asshorthand for a legal and institutional framework, there remains thequestion of whether such a framework is a spontaneous order or theproduct of purposeful experiment as Mandeville thought? Mandevillewarned about the harmful effects of meddling but his complaint wasabout the actions of fashionable do-gooders rather than government. Heunderstood that the voluntariness of a transaction could be regarded asa defence against complaints of unfairness but he was quick to pointout the limitations of voluntariness especially in the market for labour.Mandeville’s objective was to teach people what they are not what theyshould be. He pointed to the strengths of the emerging market systembut was not afraid to expose its faults.

Determining the Presence of Scour around Bridge Foundations Using Vehicle-Induced Vibrations

Bridge scour is the number one cause of failure in bridges located over waterways. Scour leads to rapid losses in foundation stiffness and can cause sudden collapse. Previous research on bridge health monitoring has used changes in natural frequency to identify damage in bridge beams. The possibility of using a similar approach to identifying scour is investigated in this paper. To assess if this approach is feasible, it is necessary to establish how scour affects the natural frequency of a bridge, and if it is possible to measure changes in frequency using the bridge dynamic response to a passing vehicle. To address these questions, a novel vehicle–bridge–soil interaction (VBSI) model was developed. By carrying out a modal study in this model, it is shown that for a wide range of possible soil states, there is a clear reduction in the natural frequency of the first mode of the bridge with scour. Moreover, it is shown that the response signals on the bridge from vehicular loading are sufficient to allow these changes in frequency to be detected.

Canada seventy years ago : or, Prince Edward's visit to Niagara /

Verse.

Horton Family collection, 1912, 1919, 1924, n.d.

Dr. William Hamilton Merritt, Jr. was born in 1865 and died in 1924. He was the son of Jedidiah Prendergast Merritt and Emily Prescott, grandson of William Hamilton Merritt. In 1892 he was married to Maud Claudman Hudson of Memphis, Tennessee and had a daughter and a son. During World War I he commanded the 14th battery at Flanders and after becoming ill served as part of the 9th Canadian Field Ambulance, 3rd Canadian Division, serving at a military hospital in Orpington, Kent, England and in 1917 at a military hospital in France. Dr. Merritt served as alderman and mayor for the city of St. Catharines, Ont. He was also a vice-president of the Imperial Bank of Canada, and served on the board of the Niagara Falls Suspension Bridge. A memorial service was held in St. Thomas Church, St. Catharines, Ont. on April 24, 1924.

James D. Tait Company Limited Fonds, 1890-1939 [non-inclusive]

James D. Tait (1836-1907) came to Canada in 1855 from Scotland. He worked in the dry goods business until he established the James D. Tait Company in 1864. The business was first located on Ontario street and specialized in furs. The business expanded to include dry goods and dress-making. After the building was destroyed by fire, Tait established and expanded the business into the Prendergast building on the corner of St. Paul and William Streets. James D. Tait died in 1907 while on vacation in Muskoka. In 1912 upon the resignation (or removal) of Benjamin Brick and Arthur Harbour, Stanley G. Smith joins the company as a director and secretary-treasurer. 1918/1919 vice-president E.J. Dignum dies. 1919 S.J. Inksater becomes a director of the company (His stock was purchased by the J.D. Tait Co.) By the 1930s the business, still in the same location, was under the leadership of Malcolm Stobie, President, Samuel J. Inksater, Vice-President and Stanley G. Smith, Secretary-Treasurer. The James D. Tait Company Limited ceased operations on 17 August 1933. The 1935 St. Catharines city directory records John Stobie, a former manager of the James D. Tait Company, operating a dry goods business at the same location, but with one-third the size of the original store space.

Uso de la matriz extracelular como material para ingeniería de tejidos

Introducción: La evaluación de injertos vasculares de submucosa de intestino delgado para la regeneración de vasos sanguíneos ha producido una permeabilidad variable (0-100%) que ha sido concurrente con la variabilidad en las técnicas de fabricación. Metodología: Investigamos los efectos de fabricación en permeabilidad y regeneración en un diseño experimental de 22factorial que combino: 1) preservación (P) o remoción (R) de la capa estratum compactum del intestino, y 2) deshidratada (D) o hidratada (H), dentro de cuatro grupos de estudio (PD, RD, PH, RH). Los injertos fueron implantados en las Arterias Carótidas de porcinos (ID 4.5mm, N=4, 7d). Permeabilidad, trombogenicidad, reacción inflamatoria, vascularización, infiltración de fibroblastos, perfil de polarización de macrófagos y fuerza tensil biaxial fueron evaluadas. Resultados: Todos los injertos PD permanecieron permeables (4/4), pero tuvieron escasa vascularización e infiltración de fibroblastos. El grupo RD permaneció permeable (4/4), presentó una extensa vascularización e infiltración de fibroblastos, y el mayor número del fenotipo de macrófagos (M2) asociado a regeneración. El grupo RH presentó menor permeabilidad (3/4), una extensa vascularización e infiltración de fibroblastos, y un perfil dominante de M2. El grupo PH presentó el menor grado de permeabilidad, y a pesar de mayor infiltración celular que PD, exhibió un fenotipo de macrófagos dominante adverso. La elasticidad de los injertos R evolucionó de una manera similar a las Carótidas nativas (particularmente RD, mientras que los injertos P mantuvieron su rigidez inicial. Discusión: Concluimos que los parámetros de fabricación afectan drásticamente los resultados, siendo los injertos RD los que arrojaron mejores resultados.

Paseando entre jardines.

Se trata de dar a conocer la exposición `jardines impresionistas´ fruto de la alianza entre el Museo Thyssen-Bornemisza y la Fundación Caja Madrid. Con esta exposición se muestra la evolución histórico-artística de la pintura de jardines desde el Romanticismo hasta las primeras vanguardias del siglo XX. El entusiasmo por la creación, el cultivo y la representación del tema del jardín dentro de la pintura impresionista se gestó ya en la Francia de mediados del siglo XIX gracias a la pasión por el cultivo de las flores. Junto a los jardines privados, los impresionistas integraron en sus obras los parques públicos que surgieron en el París de Napoleón III. Por otro lado, Pisarro, Cézanne, Gauguin, Guillaumin y Van Gogh utilizaron el tema del jardín productivo en sus inicios postimpresionistas. El tema del jardín se expandió por Europa y Estados Unidos en pintores como Klimt, Liebermann, Prendergast y Chase, entre otros.