Young people and ICT 2002: findings from a survey conducted in Autumn 2002

This report describes a survey that explored the attitudes and experiences of young people aged 5-18 and their parents, in relation to the use of information and communications technology (ICT) at home and at schoo

Reviews

Martin Oliver (ed.), Innovation in the Evaluation of Learning Technology, London: University of North London, 1998. ISBN: 1–85377–256–9. Softback, 242 pages, £15.00

Reviews

Danny Saunders and Nina Smalley (eds.), The International Simulation and Gaming Research Yearbook — Volume 8: Simulations and Games for Transition and Change, London: Kogan Page, 2000. ISBN: 0–7494–3397–3. Hardback, viii+271 pages, £40.00

Deep 15um AKARI observations in the CDFS: estimating dust luminosities for a MIR-selected sample and for Lyman Break Galaxies and the evolution of L(dust)/L(UV) with the redshift

Deep observations of the CDFS have been secured at 15um with AKARI/IRC infrared space telescope (ESA open time). From these observations, we define a sample of MIR-selected galaxies at 15um and we also obtain 15um flux densities for a sample of LBGs at z=1 already observed at 24um with Spitzer/MIPS. Number counts for the MIR-selected sample show a bump around a 15um flux density of 0.2mJy that can be attributed to galaxies at z>0.4 and at z>0.8 for the fainter part of the bump. This bump seems to be shifted as compared to other works and a possible origin can be the Cosmic variance. Thanks to this dataset, we have tested, on the two above samples at z=1, the validity of the conversions from monochromatic luminosities nu.f(nu) at a rest-frame wavelength of 8um by a comparison with total dust luminosities estimated from Spitzer rest-frame 12um data that we use as a reference. We find that the 8um dust luminosities are not all consistent and that some of them are better when compared to L(dust) evaluated from longer wavelength luminosities. We also find that the rest-frame 8um luminosities provide globally good estimates of L(dust). By comparing our data for the two samples to several libraries of SEDs, we find that models can explain the diversity of the observed f(24)/f(15) ratio quite reasonably for the MIR-selected sample and better for the LBG sample which are less dispersed than the MIR selection. However, when we analyse the luminosity dependence of this ratio, we find important discrepancies. Finally, we revisit the evolution of L(dust)/L(UV) ratio with the redshift z by re-calibrating previous L(dust) at z=2 based on our results and added new data points at higher redshifts. The decreasing trend is amplified as compared to the previous estimate.Comment: Paper accepted for publication in PAS

Spitzer and ISO Galaxy Counts in the Mid-Infrared

Galaxy source counts that simultaneously fit the deep mid-infrared surveys at 24 microns and 15 microns made by the Spitzer Space Telescope and the Infrared Space Observatory (ISO) respectively are presented for two phenomenological models. The models are based on starburst and luminous infrared galaxy dominated populations. Both models produce excellent fits to the counts in both wavebands and provide an explanation for the high redshift population seen in the longer Spitzer 24 micron band supporting the hypothesis that they are luminous-ultraluminous infrared galaxies at z=2-3, being the mid-infrared counterparts to the sub-mm galaxy population. The source counts are characterized by strong evolution to redshift unity, followed by less drastic evolution to higher redshift. The number-redshift distributions in both wavebands are well explained by the effect of the many mid-infrared features passing through the observation windows. The sharp upturn at around a milliJansky in the 15 micron counts in particular depends critically on the distribution of mid-infrared features around 12 microns, in the assumed spectral energy distribution.Comment: 6 pages, 2 figures, accepted for publication MNRA

Detection of CFIRB with AKARI/FIS Deep Observations

The Cosmic Far-Infrared Background (CFIRB) contains information about the number and distribution of contributing sources and thus gives us an important key to understand the evolution of galaxies. Using a confusion study to set a fundamental limit to the observations, we investigate the potential to explore the CFIRB with AKARI/FIS deep observations. The Far-Infrared Surveyor (FIS) is one of the focal-plane instruments on the AKARI (formerly known as ASTRO-F) satellite, which was launched in early 2006. Based upon source distribution models assuming three different cosmological evolutionary scenarios (no evolution, weak evolution, and strong evolution), an extensive model for diffuse emission from infrared cirrus, and instrumental noise estimates, we present a comprehensive analysis for the determination of the confusion levels for deep far-infrared observations. We use our derived sensitivities to suggest the best observational strategy for the AKARI/FIS mission to detect the CFIRB fluctuations. If the source distribution follows the evolutionary models, observations will be mostly limited by source confusion. We find that we will be able to detect the CFIRB fluctuations and that these will in turn provide information to discriminate between the evolutionary scenarios of galaxies in most low-to-medium cirrus regions.Comment: 12 pages, 5 figures, uses elsart.cls, Accepted for publication in Advances in Space Research, 36th COSPAR Scientific Assembly Beijing, China, 16 ~ 23 July 200

<i>AKARI</i>/IRC source catalogues and source counts for the IRAC Dark Field, ELAIS North and the <i>AKARI</i> Deep Field South

We present the first detailed analysis of three extragalactic fields (IRAC Dark Field, ELAIS-N1, ADF-S) observed by the infrared satellite, AKARI, using an optimized data analysis toolkit specifically for the processing of extragalactic point sources. The InfaRed Camera (IRC) on AKARI complements the SpitzerSpace Telescope via its comprehensive coverage between 8–24 μm filling the gap between the Spitzer/IRAC and MIPS instruments. Source counts in the AKARI bands at 3.2, 4.1, 7, 11, 15 and 18 μm are presented. At near-infrared wavelengths, our source counts are consistent with counts made in other AKARI fields and in general with SpitzerIRAC (except at 3.2 μm where our counts lie above). In the mid-infrared (11 – 18 μm), we find our counts are consistent with both previous surveys by AKARI and the Spitzer peak-up imaging survey with the InfraRed Spectrograph (IRS). Using our counts to constrain contemporary evolutionary models, we find that although the models and counts are in agreement at mid-infrared wavelengths there are inconsistencies at wavelengths shortward of 7 μm, suggesting either a problem with stellar subtraction or indicating the need for refinement of the stellar population models. We have also investigated the AKARI/IRC filters, and find an active galactic nucleus selection criteria out to z AKARI 4.1, 11, 15 and 18 μm colours