8,148 research outputs found
Mixed mode education: implications for library user services
The Faculty of Information Technology at QUT does not formally carry out distance education for any of its courses. However, it has pursued a number of initiatives that have made it possible for students to carry out an increasing proportion of their coursework off-site. These initiatives include computer-managed learning, World Wide Web and CDROM delivery of administrative and educational materials, and most recently the development of an integrated learning environment (ILE) for electronic delivery. These developments have been complemented and supported by the QUT Library by means of different avenues of access to CDROMs, a regional electronic document delivery service (REDD), and an electronic reserve (E-Reserve) service. Issues associated with the operation and evaluation of such facilities are described, and future library role in educational delivery are discussed
Nonlinear Gravitational Clustering: dreams of a paradigm
We discuss the late time evolution of the gravitational clustering in an
expanding universe, based on the nonlinear scaling relations (NSR) which
connect the nonlinear and linear two point correlation functions. The existence
of critical indices for the NSR suggests that the evolution may proceed towards
a universal profile which does not change its shape at late times. We begin by
clarifying the relation between the density profiles of the individual halo and
the slope of the correlation function and discuss the conditions under which
the slopes of the correlation function at the extreme nonlinear end can be
independent of the initial power spectrum. If the evolution should lead to a
profile which preserves the shape at late times, then the correlation function
should grow as [in a universe] een at nonlinear scales. We
prove that such exact solutions do not exist; however, ther e exists a class of
solutions (``psuedo-linear profiles'', PLP's for short) which evolve as
to a good approximation. It turns out that the PLP's are the correlation
functions which arise if the individual halos are assumed to be isothermal
spheres. They are also configurations of mass in which the nonlinear effects of
gravitational clustering is a minimum and hence can act as building blocks of
the nonlinear universe. We discuss the implicatios of this result.Comment: 32 Pages, Submitted to Ap
The scale of homogeneity in the Las Campanas Redshift Survey
We analyse the Las Campanas Redshift Survey using the integrated conditional
density (or density of neighbors) in volume-limited subsamples up to
unprecedented scales (200 Mpc/) in order to determine without ambiguity the
behavior of the density field. We find that the survey is well described by a
fractal up to 20-30 Mpc/, but flattens toward homogeneity at larger scales.
Although the data are still insufficient to establish with high significance
the expected homogeneous behavior, and therefore to rule out a fractal trend to
larger scales, a fit with a CDM-like spectrum with high normalization well
represents the data.Comment: 8 pages, 3 figures, accepted on Ap.J. Letter
The results of prolonged administration of isoniazid to mice, rats and hamsters.
THE demonstration that isoniazid (INH) is carcinogenic for the lungs of mice (Juhasz, Balo and Kendrey, 1957) raised a new type of cancer problem. Most known carcinogens are avoidable as human hazards and many are subject to restrictive legislation. However, INH is a valuable life-saving drug in the control of tuberculosis, and the assessment of it as a potential carcinogenic hazard for man is therefore a matter of unusual concern. Moreover, it must be noted that the induction of pulmonary alveolar adenoma or adenocarcinoma in mice by a variety of chemically dissimilar carcinogens (e.g. urethane and 4-nitro-quinoline-N-oxide) is most striking in those strains, such as A and BALB/c, which have a high spontaneous incidence of such tumours. Tumours of similar histogenesis can be induced experimentally in rats but they very rarely occur spontaneously. In terms of initiators and promoters, mice of different strains behave as though they have variable amounts of some inborn initiator which determines the response of their alveolar cells to a variety of carcinogenic promoters. Apart from known genetic factors no " initiator " a
Amplitude and Phase Fluctuations for Gravitational Waves Propagating through Inhomogeneous Mass Distribution in the Universe
When a gravitational wave (GW) from a distant source propagates through the
universe, its amplitude and phase change due to gravitational lensing by the
inhomogeneous mass distribution. We derive the amplitude and phase
fluctuations, and calculate these variances in the limit of a weak
gravitational field of density perturbation. If the scale of the perturbation
is smaller than the Fresnel scale ( is the
GW frequency), the GW is not magnified due to the diffraction effect. The rms
amplitude fluctuation is for Hz, but it is reduced less
than 5% for a very low frequency of Hz. The rms phase
fluctuation in the chirp signal is radian at LISA frequency band
( Hz). Measurements of these fluctuations will provide
information about the matter power spectrum on the Fresnel scale pc.Comment: 6 pages, 6 figures, refferences added, accepted for publication in
Ap
Attraction of Acorn-Infesting \u3ci\u3eCydia Latiferreana\u3c/i\u3e (Lepidoptera: Tortricidae) to Pheromone-Baited Traps
Males of acorn-infesting Cydia latiferreana are attracted to an equilibrium mixture of the four isomers of 8, 10-dodecadien-l-ol acetate, the virgin female-produced pheromone. Trap height relative to the height of trees in which traps are placed seems to be a significant factor influencing moth catches at attractant-baited traps. In an oak woodlot and in an oak nursery, catches of male moths were greater in traps placed near the upper periphery of the canopy than at traps deployed at lower levels in the tree. Practical application of pheromone-baited traps in a forest situation will require further study on lure formulation and on trap deployment under forest conditions
Spontaneous and induced hyperplasia and neoplasia in the mouse lung.
,SINCE Livingood (1896) first described a spontaneous pulmonary tumour in a mouse, much has been written on the histogenesis of this common tumour, vet it is still difficult to decide whether an early lesion should be classified as hyperplastic or neoplastic. Since the introduction of line-bred strains of mice by Strong (1936) and their general use by research workers, genetic differences in susceptibility have been extensively investigated by Heston (1940) and manv others. It is accepted that the susceptibility to spontaneous development of pulmonary tumours is high in A Strain and low in C57 Black, but that there is no essential difference between the type or range of tumours seen in different strains (Stewart, 1953). As to the sites of origin and distribution of these tumours, most authors describe them as subpleural and as originating in the alveolar epithelium. As far as we know, there has been no evidence as to localising factors which cause one alveolus rather than another to develop neoplastic growth
- …