Unfolding Orthogonal Polyhedra with Quadratic Refinement: The Delta-Unfolding Algorithm

We show that every orthogonal polyhedron homeomorphic to a sphere can be unfolded without overlap while using only polynomially many (orthogonal) cuts. By contrast, the best previous such result used exponentially many cuts. More precisely, given an orthogonal polyhedron with n vertices, the algorithm cuts the polyhedron only where it is met by the grid of coordinate planes passing through the vertices, together with Theta(n^2) additional coordinate planes between every two such grid planes.Comment: 15 pages, 10 figure

Conversion of relic gravitational waves into photons in cosmological magnetic fields

Conversion of gravitational waves into electromagnetic radiation is discussed. The probability of transformations of gravitons into photons in presence of cosmological background magnetic field is calculated at the recombination epoch and during subsequent cosmological stages. The produced electromagnetic radiation is concentrated in the X-ray part of the spectrum. It is shown that if the early Universe was dominated by primordial black holes (PBHs) prior to Big Bang Nucleosynthesis (BBN), the relic gravitons emitted by PBHs would transform to an almost isotropic background of electromagnetic radiation due to conversion of gravitons into photons in cosmological magnetic fields. Such extragalactic radiation could be noticeable or even dominant component of Cosmic X-ray Background.Comment: 24 pages, 8 figures and 1 table; minor changes and more references have been adde

Heathland Restoration Techniques: Ecological Consequences for Plant-Soil and Plant-Animal Interactions

We compare the soil and plant community development during heathland restoration on improved farmland when achieved through soil stripping with that achieved through soil acidification. We also test the potential for toxic metals to be made more available to plant and animal species as a result of these treatments. Acidification with elemental sulphur was found to be more effective than soil stripping for establishing an ericaceous sward despite the high levels of phosphate still present within the soil.However, both soil acidification and soil stripping were found to have the potential to increase the availability of potentially toxic metals. Acidification increased uptake of both aluminium and zinc in two common plant species Agrostis capillaris and Rumex acetosella and decreased the abundance of surface active spiders. The potential consequences for composition of restored heathland communities and for functioning of food chains are discussed

Gender Differences in Cognitive Ability of Children with Hearing Impairment on the Wechsler Intelligence Scale for Children-3rd Edition

This research thesis investigates possible gender differences of deaf children on the Wechsler Intelligence Scale for Children (3rd ed.). The Illinois School for the Deaf (ISD) in Jacksonville, Illinois collated the standard scores of the five standard WISC-III Performance scale subtests and the Performance IQ of 25 students attending ISD. To examine gender differences on the Performance scale subtests and the Performance IQ\u27s, a series of oneway-analyses of variance was calculated. No significant differences were noted on any comparison. A hypothesis that gender differences would occur was not confirmed. The results are discussed with respect to the intellectual assessment of all persons who are deaf

An insight into the interplay between culture, conflict and distance in globally distributed requirements negotiations

© 2003 IEEE. There is an increasing interest in research addressing issues of global software development. Specifying software requirements is a communication-intensive collaborative activity that is increasingly performed across cultural, language and time zone boundaries. While inadequate communication significantly impacts the bridging of geographical distance between stakeholders, the cultural differences cannot be considered less significant. Findings from two global software development organizations enables us to present a model of impact of distance and the affected requirements activities due to problems of cultural diversity, inadequate communication, knowledge management and time differences. This evidence provides an important insight into the interplay between culture and conflict as well as the impact of distance on the ability to reconcile different viewpoints with regards to requirements and requirements processes