27 research outputs found
Relativistic Binaries in Globular Clusters
Galactic globular clusters are old, dense star systems typically containing
10\super{4}--10\super{7} stars. As an old population of stars, globular
clusters contain many collapsed and degenerate objects. As a dense population
of stars, globular clusters are the scene of many interesting close dynamical
interactions between stars. These dynamical interactions can alter the
evolution of individual stars and can produce tight binary systems containing
one or two compact objects. In this review, we discuss theoretical models of
globular cluster evolution and binary evolution, techniques for simulating this
evolution that leads to relativistic binaries, and current and possible future
observational evidence for this population. Our discussion of globular cluster
evolution will focus on the processes that boost the production of hard binary
systems and the subsequent interaction of these binaries that can alter the
properties of both bodies and can lead to exotic objects. Direct {\it N}-body
integrations and Fokker--Planck simulations of the evolution of globular
clusters that incorporate tidal interactions and lead to predictions of
relativistic binary populations are also discussed. We discuss the current
observational evidence for cataclysmic variables, millisecond pulsars, and
low-mass X-ray binaries as well as possible future detection of relativistic
binaries with gravitational radiation.Comment: 88 pages, 13 figures. Submitted update of Living Reviews articl
Economical regulation power through load shifting with smart energy appliances
This paper considers the technical and economical feasibility of the introduction of automated demand response from domestic smart appliances in a European setting as a means to create a significant amount of regulating power. Simplified power-time flexibility models for appliances are introduced on which generic economic simulations can be based. These simulations permit a good indication of the economic value that can be attained as a function of model parameters. This shows that classical load shifting of washing appliances creates sufficient value in the day-ahead market to justify investments in smart energy control services. Cooling appliances create significant value on the balance market and while full scale deployment would lead to significant price erosion in today's market, it could accommodate additional unbalance caused future sustainable generation. The scale of domestic demand response resources can be quantified in two simple parameters: regulation power and storage capacity. For the Dutch situation these are 700 MW, equivalent to 5% of average national power consumption and 5 GWh storage: around 20 minutes of average national power consumption. Smart appliances can deliver a 100% efficient and CO2 friendly complement to the unpredictability of e.g., large scale wind power as planned in large parts of Europe in 10 to 15 years
Beyond the Parental Generation : The Influence of Grandfathers and Great-grandfathers on Status Attainment
Studies on intergenerational social mobility usually examine the extent to which social positions of one generation determine the social positions of the next. This study investigates whether the persistence of inequality can be expected to stretch over more than two generations. Using a multigenerational version of GENLIAS, a large-scale database containing information from digitized Dutch marriage certificates during 1812–1922, this study describes and explains the influence of grandfathers and great-grandfathers on the occupational status attainment of 119,662 men in the Netherlands during industrialization. Multilevel regression models show that both grandfather’s and great-grandfather’s status influence the status attainment of men, after fathers and uncles are taken into account. Whereas the influence of the father and uncles decreases over time, that of the grandfather and great-grandfather remains stable. The results further suggest that grandfathers influence their grandsons through contact but also without being in contact with them. Although the gain in terms of explained variance from using a multigenerational model is moderate, leaving out the influence of the extended family considerably misrepresents the influence of the family on status attainment