OBJECTS IN TIME

Two recent lines of database research, proceeding independently, have been concerned with providing a richer, more intuitive view of information at the user level. Historical database research has focused on ways to provide users with a view of information anchored and evolving in the temporal dimension. Object-oriented database research focuses on encapsulating both the structure and the behavior of the objects that users intend to model. In this paper we explore how these two lines of research might be brought together, providing to the user the representation and management of objects in time.Information Systems Working Papers Serie

Time Lags in Compact Objects: Constraints on the Emission Models

Accreting black holes and neutron stars in their hard (low) state show not only very similar X/gamma-ray spectra but also that the behaviour of their light curves is quite similar which can be quantified as having similar power-density spectra and Fourier-frequency-dependent time/phase lags. Taken together this argues for a common mechanism of the X/gamma-ray production in these objects. This mechanism is probably a property of the accretion flow only since it does not depend on the nature of the compact object. In this paper, I review the observational data paying most attention to the properties of the temporal variability such as the time/phase lags that hopefully can help us to discriminate between different theoretical models. I also discuss the models developed to account for the basic observational facts. Particularly, I show that the commonly used Compton cloud models with constant temperature cannot explain variable sources without violating the energy conservation law. Alternative models where time lags are related to the spectral evolution during X-ray flares are discussed and compared with observations. Compton reflection from the outer edge of the accretion disc is shown to markedly affect the time lag Fourier spectrum.Comment: 16 pages; invited talk at the meeting "X-ray Astronomy 1999: Stellar Endpoints, AGN and the Diffuse Background", held in Bologna, Italy, September 199

Finding Pairwise Intersections Inside a Query Range

We study the following problem: preprocess a set O of objects into a data structure that allows us to efficiently report all pairs of objects from O that intersect inside an axis-aligned query range Q. We present data structures of size $O(n({\rm polylog} n))$ and with query time $O((k+1)({\rm polylog} n))$ time, where k is the number of reported pairs, for two classes of objects in the plane: axis-aligned rectangles and objects with small union complexity. For the 3-dimensional case where the objects and the query range are axis-aligned boxes in R^3, we present a data structures of size $O(n\sqrt{n}({\rm polylog} n))$ and query time $O((\sqrt{n}+k)({\rm polylog} n))$. When the objects and query are fat, we obtain $O((k+1)({\rm polylog} n))$ query time using $O(n({\rm polylog} n))$ storage

Lumensecity: Objects Illuminated in Time

This thesis explores the evolution of my work in graduate school. Upon entering into this course of study my artistic expression was polarized into realms of 2 and 3-Dimensional tactile works and experiments in 4-Dimensions (time) in the form of animations and short films. The content and context of these works have interwoven but their presentations remained polarized. In my masterʼs studies I have attempted to synergize the mediums of my artworks in order to achieve more realized and formal presentations. Following this course, I hope for my work to further evolve

Abstract Objects in a Metaphysical Perspective

The article presents an unconventional although not absolutely unprecedented view on abstract objects defending the position of metaphysical realism. It is argued that abstract objects taken in purely ontological sense are the forms of objects. The forms possess some common characteristics of abstract objects, they can exist not in physical space and time and play a grounding role in their relation to concrete objects. It is stated that commonly discussed abstract objects – properties, kinds, mathematical objects – are forms