Secant varieties of toric varieties

Let $X_P$ be a smooth projective toric variety of dimension $n$ embedded in \PP^r using all of the lattice points of the polytope $P$. We compute the dimension and degree of the secant variety \Sec X_P. We also give explicit formulas in dimensions 2 and 3 and obtain partial results for the projective varieties $X_A$ embedded using a set of lattice points A \subset P\cap\ZZ^n containing the vertices of $P$ and their nearest neighbors.Comment: v1, AMS LaTex, 5 figures, 25 pages; v2, reference added; v3, This is a major rewrite. We have strengthened our main results to include a classification of smooth lattice polytopes P such that Sec X_P does not have the expected dimension. (See Theorems 1.4 and 1.5.) There was also a considerable amount of reorganization, and some expository material was eliminated; v4, 28 pages, minor corrections, additional and updated reference

LOW BPR TURBOFAN PERFORMANCE WITH POWER EXTRACTION

Military aircraft require more electrical power than they used to do. The increased power consumption is dueto a transition from pneumatic and hydraulic systems to electrical and the introduction of new, more powerconsuming equipment. This paper summarizes an engine performance study, performed with a modeled lowbypass ratio mixed flow turbofan engine, where power is extracted from the low-pressure shaft, the highpressureshaft or a combination of the two. High-pressure shaft power extraction results in a considerableturbine inlet temperature increase. If the operating point has sufficient margin to the maximum turbine inlettemperature limit and if the power extraction is acceptable from an operability point of view, power can beextracted from the high-pressure shaft without causing much penalty on engine thrust. If the engine is runningclose to its maximum turbine inlet temperature, which is typically the case at low altitude and high aircraftspeed, power extraction from the low-pressure shaft could be a better alternative due to the lower turbine inlettemperature increase. This gives a higher margin to the maximum turbine inlet temperature limit. However, ifthe full potential of low-pressure shaft power extraction is to be utilized, the high-pressure compressor musthave some aerodynamic overspeed margin for the low-pressure shaft power extraction case. At part power,the lower specific thrust of the low-pressure shaft extraction case compared to the high-pressure shaft powerextraction case, is favorable from a propulsive efficiency and fuel consumption perspective

Diversity and power in the world city network

There are three purposes: (1) to illustrate diversity amongst world cities; (2) to show how this reflects/constitutes power relativities between cities; and (3) to place debates on diversity and power on a firm empirical basis. The power of cities is interpreted both as a capacity (‘power over’) and as a medium (‘power to’). World cities are treated as global service centres and the world city network is conceptualised as being ‘interlocked’ through provision of business and financial services by global firms. The study is primarily empirical and uses a global data set comprising information on 100 global service firms in 123 world cities. Seven different ways of measuring and illustrating power differentials are presented: global network connectivity, banking/finance connectivity, dominant centres, global command centres, regional command centres, high connectivity gateways, and gateways to emerging markets. These categories have been identified before but never specified as comprehensively and rigorously as here. Whereas power as command power is concentrated in the USA, western Europe and Tokyo, network power is much more geographically diffused transcending the old ‘North-South divide’. Finally the focus on diversity makes problematic the lazy policy tendency for emulation of a few well-known ‘global cities’

Femoral artery ultrasound examination: a new role in predicting cardiovascular risk

We compared intima-media thickness (IMT) and the prevalence of plaques in the common carotid artery (CCA) and common femoral artery (CFA) in apparently healthy participants. This multicenter study included 322 participants (59.9% female; age 20-78 years, mean 52.1 ± 15.3 years) who underwent Echo-color Doppler examination of the CCA and CFA bilaterally. Prevalence and composition of plaque were recorded. A significant ( P < .01) difference between mean CCA-IMT and mean CFA-IMT was detected (0.70 vs 0.73 mm). Plaque prevalence was significantly higher in the CFA compared to the CCA (40.7% vs 30.4%). Atherosclerotic plaques were found in both CFA and CCA in 46% of the cases, solely in CFA in 38%, and in CCA alone in 17%. The observed difference in plaque prevalence was even greater when only fibrolipid isolated plaques were considered (CFA 39.4% vs CCA 22.1%). In a healthy general population, atherosclerotic plaques were present in the CFA but not in the CCA in over one-third of the cases. Further studies must confirm whether ultrasonography of the CFA might be introduced in the screening protocols for cardiovascular risk assessment

Password-Authenticated Group Key Agreement with Adaptive Security and Contributiveness

The original publication is available at www.springerlink.comInternational audienceAdaptively-secure key exchange allows the establishment of secure channels even in the presence of an adversary that can corrupt parties adaptively and obtain their internal states. In this paper, we give a formal definition of contributory protocols and define an ideal functionality for password-based group key exchange with explicit authentication and contributiveness in the UC framework. As with previous definitions in the same framework, our definitions do not assume any particular distribution on passwords or independence between passwords of different parties. We also provide the first steps toward realizing this functionality in the above strong adaptive setting by analyzing an efficient existing protocol and showing that it realizes the ideal functionality in the random-oracle and ideal-cipher models based on the CDH assumption

2024 Inequality Landscape : Health and Socioeconomic Divides in Scotland

This report is the first major output by the Scottish Health Equity Research Unit (SHERU) since its creation earlier this year. It examines how Scotland is faring regarding key health-related policies since the last suite of reports published as part of the Health Foundation’s independent review in 2023. Our focus is on the main socioeconomic factors that affect health and inequalities

Health Inequalities in Scotland : Trends in the Socio-economic Determinants of Health in Scotland

Socioeconomic factors play a critical role in influencing health and health inequalities. These socioeconomic factors include the pay, security and nature of the jobs that people do. They include households’ financial security, which influences the extent to which people are exposed to stress and anxiety, the time and resources people have to adopt healthy behaviours, and their ability to secure a decent standard of living generally. They also include the physical environment in which people live, both in terms of housing – poor quality or overcrowded housing can affect health in various ways – and neighbourhoods more generally (which influence opportunities for work, play and exercise, and exposure to pollution). The aim of this report is to examine trends in key socioeconomic determinants of health in Scotland since 1999, the year of the establishment of the Scottish parliament. The report is based on six thematic chapters which examine trends in: the labour market; household income and financial security; education and social mobility; housing; public services; and neighbourhoods. A seventh chapter examines trends in socioeconomic determinants of health during the Covid-19 pandemic and the emerging cost-of-living crisis