Effect of stress and temperature on the optical properties of silicon nitride membranes at 1550 nm

Future gravitational-wave detectors operated at cryogenic temperatures are expected to be limited by thermal noise of the highly reflective mirror coatings. Silicon nitride is an interesting material for such coatings as it shows very low mechanical loss, a property related to low thermal noise, which is known to further decrease under stress. Low optical absorption is also required to maintain the low mirror temperature. Here, we investigate the effect of stress on the optical properties at 1,550 nm of silicon nitride membranes attached to a silicon frame. Our approach includes the measurement of the thermal expansion coefficient and the thermal conductivity of the membranes. The membrane and frame temperatures are varied, and translated into a change in stress using finite element modeling. The resulting product of the optical absorption and thermo-optic coefficient (dn/dT) is measured using photothermal common-path interferometry

Scottish leaders’ debates on Twitter: Sturgeon, Davidson, and ‘indyref2’ dominated proceedings

As the dust begins to settle on the 2017 General Election campaign, Graeme Baxter, Simon Burnett, John Isaacs, Iain MacLeod, Sarah Pedersen, and Elizabeth Tait reflect upon the Twitter response to the two televised Scottish leaders’ debates held in the lead-up to polling day

New radicals: digital political engagement in post-referendum Scotland: final report on pilot project to the communities and cultrue network+.

The main aim of this study will be to analyse the transition of social media activism since the Scottish referendum, in order to establish whether the related activism is sustained over a longer timescale, particularly in relation to younger voters. The objectives of the proposed study will be: To map and disaggregate post-referendum social media activity using social network analysis techniques To investigate the discourses and emerging narratives of the groups using digital ethnographic research To investigate the breadth and depth of engagement by conducting interviews with members of the groups (including political parties and civic campaign groups) To conduct a targeted investigation of engagement of young voters (especially those aged 16-17 at the time of the referendum) to determine whether the engagement levels in relation to the referendum are translating into broader engagement with politics

The Scottish economy [February 1986]

With the inauguration of the quarterly Scottish Business Survey (SBS) in September 1984 there are now two regular up-to-date indicators of trends in the Scottish industrial sector. The combination of the new survey and the long-standing CBI Industrial Trends Survey provides a comprehensive assessment of trends in Scottish industry. The two data sources are essentially complementary, but there are important differences between them

The British economy [February 1986]

Growth in the UK economy looks set to continue in 1986 although at a lower rate than in preceding years. Consumer expenditure will play a dominant role in determining growth while exports and investment will expand less rapidly than in 1985. In the November Statement the Chancellor forecast further reductions in the inflation rate and reductions in income tax in the Spring Budget. Unlike previous years, however, the Chancellor provided no clear indication of the likely scale of tax cuts. Avoidance of any specific commitment has now been proven wise as the Exchequer's revenues have been reduced by falling oil prices

Outlook and appraisal [February 1986]

During the course of 1986 economic growth in Scotland and in the rest of the UK is likely to proceed less rapidly than in 1985. Moreover, changes in the Scottish pattern of growth will reflect those taking place in the UK generally and in other European economies

The world economy [February 1986]

The present recovery in the world economy has now proceeded for almost twice as long as the typical cyclical phase of expansion during the past four decades. Growth in 1985 and prospective growth for 1986 is, however, modest in comparison to both the rates achieved in earlier upswings and that of 1983-4 when world expansion was driven by the strong growth of the US economy. With the deceleration of the US economy from its phase of rapid expansion and the continuing policy caution in the countries of Western Europe and Japan, growth in the major industrialised economies is likely to be of the order of 2.5% in 1986

The Scottish economy [February 1985]

With the inauguration of the quarterly Scottish Business Survey (SBS) in September 1984 there are now two regular and up-to-date indicators of trends in the Scottish industrial sector. The combination of the new survey and the long-standing CBI Industrial Trends Survey provides a comprehensive assessment of trends in Scottish industry