Ubiquitous computing and knowledge management

MOBIlearn is a large European research project to develop a mobile learning system to facilitate formal, non formal and informal learning. The project has two primary objectives: • Develop a methodology for creating mobile learning scenarios and producing learning objects to implement them. • Develop the technology to deliver the learning objects to users via mobile computing devices. This paper will concentrate the MOBIlearn health care domain. One of this applications main objectives is managing and sharing of tacit knowledge. Using the system participants discuss case studies and alternative approaches to specific problems are evaluated and documented. This is then used and extended in future case studies. In a mobile learning environment, individual health workers can use the system to either advanced their skills, or in a ‘live’ incident, use it for reference and indeed call for backup.</p

Benjamin Franklin and the leather-apron men: the politics of class in eighteenth-century Philadelphia

Benjamin Franklin's autobiography reveals his deep investment in shaping and controlling how both his contemporaries and posterity assessed his life and achievements. This essay explores Franklin's construction and presentation of his pride in his working-class origins and identity, analysing how and why Franklin sought not to hide his poor origins but rather to celebrate them as a virtue. As an extremely successful printer, Franklin had risen from working-class obscurity to the highest ranks of Philadelphia society, yet unlike other self-made men of the era Franklin embraced and celebrated his artisanal roots, and he made deliberate use of his working-class identity during the Seven Years War and the subsequent imperial crisis, thereby consolidating his own reputation and firming up the support of urban workers who considered him one of their own

How extreme are the Wolf-Rayet clusters in NGC3125?

We reinvestigate the massive stellar content of NGC3125 (Tol3) using VLT/FORS1 imaging & spectroscopy, plus archival VLT/ISAAC, HST/FOC and HST/STIS datasets. Narrow-band imaging confirms that A and B knots represent the primary sites of Wolf-Rayet (WR) stars, whilst HST imaging reveals that both regions host multiple clusters. Clusters A1 + A2 within region A host WR stars. altough is not clear which cluster within region B hosts WR stars. Nebular properties infer an LMC-like metallicity. LMC template WN5-6 & WC4 spectra are matched to the observed optical WR bumps of A1 and B, permitting the contribution of WC stars to the blue bump to be quantified. We obtain N(WN5-6:WC4)=105:20, 55:0, 40:20 for clusters A1, A2 and B1+B2, a factor of 3 lower than optical studies, as a result of a lower E(B-V). Using Starburst99 models to estimate O star populations for individual clusters, we find N(WR)/N(O)=0.2 for A1 and 0.1 for A2 and B1+B2. From Halpha imaging, the O star content of the Giant HII regions A and B is found to be a factor of 5-10 times higher than that derived spectroscopically for the UV/optically bright clusters, suggesting that NGC3125 hosts optically obscured young massive clusters, further supported by VLT/ISAAC K band imaging. Archival HST/STIS UV spectroscopy confirms the low E(B-V) towards A1, for which we have determined an SMC extinction law, in preference to an LMC or starburst law. We obtain N(WN5-6)=110 from the slit-loss corrected HeII 1640 line flux, in excellent agreement with optical result. However, this is a factor of 35 times lower than that inferred from the same dataset by Chandar et al. due to their use of a starburst extinction law. Highly discrepant stellar populations may result in spatially resolved star forming regions from UV and optical studies through use of different extinction laws.Comment: 12 pages, 8 figures, accepted for MNRAS (fixes previous error in Table 2

A downward revision to the distance of the 1806-20 cluster and associated magnetar from Gemini near-Infrared spectroscopy

We present H- and K-band spectroscopy of OB and Wolf-Rayet (WR) members of the Milky Way cluster 1806-20 (G10.0-0.3), to obtain a revised cluster distance of relevance to the 2004 giant flare from the SGR 1806-20 magnetar. From GNIRS spectroscopy obtained with Gemini South, four candidate OB stars are confirmed as late O/early B supergiants, while we support previous mid WN and late WC classifications for two WR stars. Based upon an absolute Ks-band magnitude calibration for B supergiants and WR stars, and near-IR photometry from NIRI at Gemini North plus archival VLT/ISAAC datasets, we obtain a cluster distance modulus of 14.7+/-0.35 mag. The known stellar content of the 1806-20 cluster suggests an age of 3-5 Myr, from which theoretical isochrone fits infer a distance modulus of 14.7+/-0.7 mag. Together, our results favour a distance modulus of 14.7+/-0.4 mag (8.7^+1.8_-1.5 kpc) to the 1806-20 cluster, which is significantly lower than the nominal 15 kpc distance to the magnetar. For our preferred distance, the peak luminosity of the December 2004 giant flare is reduced by a factor of three to 7 X 10^46 erg/s, such that the contamination of BATSE short gamma ray bursts (GRB's) from giant flares of extragalactic magnetars is reduced to a few percent. We infer a magnetar progenitor mass of ~48^+20_-8 Msun, in close agreement with that obtained recently for the magnetar in Westerlund 1.Comment: 6 pages, 4 figures, accepted for MNRAS Letter

A survey of the Wolf-Rayet population of the barred, spiral galaxy NGC 1313

We present a VLT/FORS1 survey of Wolf-Rayet (WR) stars in the spiral galaxy NGC 1313. In total, 94 WR candidate sources have been identified from narrow-band imaging. Of these, 82 have been spectroscopically observed, for which WR emission features are confirmed in 70 cases, one of which also exhibits strong nebular HeII 4686 emission. We also detect strong nebular HeII 4686 emission within two other regions of NGC 1313, one of which is a possible supernova remnant. Nebular properties confirm that NGC 1313 has a metal-content log(O/H)+12=8.23+/-0.06, in good agreement with previous studies. From continuum subtracted Halpha images we infer a global star formation rate of 0.6 Msun/yr. Using template LMC WR stars, spectroscopy reveals that NGC 1313 hosts a minimum of 84 WR stars. Our census comprises 51 WN stars, including a rare WN/C transition star plus 32 WC stars. In addition, we identify one WO star which represents the first such case identified beyond the Local Group. The bright giant HII region PES 1, comparable in Halpha luminosity to NGC 595 in M 33, is found to host a minimum of 17 WR stars. The remaining photometric candidates generally display photometric properties consistent with WN stars, such that we expect a global WR population of ~115 stars with N(WR)/N(O)~0.01 and N(WC)/N(WN)~0.4.Comment: Accepted for publication in MNRAS. Finding charts omitted, full version available by anonymous ftp (ftp: hydra.shef.ac.uk/pub/lh/ngc1313-fullversion.pd

Metallicity in the Galactic Center: The Arches cluster

We present a quantitative spectral analysis of five very massive stars in the Arches cluster, located near the Galactic center, to determine stellar parameters, stellar wind properties and, most importantly, metallicity content. The analysis uses a new technique, presented here for the first time, and uses line-blanketed NLTE wind/atmosphere models fit to high-resolution near-infrared spectra of late-type nitrogen-rich Wolf-Rayet stars and OfI+ stars in the cluster. It relies on the fact that massive stars reach a maximum nitrogen abundance that is related to initial metallicity when they are in the WNL phase. We determine the present-day nitrogen abundance of the WNL stars in the Arches cluster to be 1.6% (mass fraction) and constrain the stellar metallicity in the cluster to be solar. This result is invariant to assumptions about the mass-luminosity relationship, the mass-loss rates, and rotation speeds. In addition, from this analysis, we find the age of the Arches cluster to be 2-2.5Myr, assuming coeval formation

A Very Large Telescope imaging and spectroscopic survey of the Wolf-Rayet population in NGC 7793

We present a VLT/FORS1 imaging and spectroscopic survey of the Wolf-Rayet (WR) population in the Sculptor group spiral galaxy NGC 7793. We identify 74 emission line candidates from archival narrow-band imaging, from which 39 were observed with the Multi Object Spectroscopy (MOS) mode of FORS1. 85% of these sources displayed WR features. Additional slits were used to observe HII regions, enabling an estimate of the metallicity gradient of NGC 7793 using strong line calibrations, from which a central oxygen content of log (O/H) + 12 = 8.6 was obtained, falling to 8.25 at R_25. We have estimated WR populations using a calibration of line luminosities of Large Magellanic Cloud stars, revealing ~27 WN and ~25 WC stars from 29 sources spectroscopically observed. Photometric properties of the remaining candidates suggest an additional ~27 WN and ~8 WC stars. A comparison with the WR census of the LMC suggests that our imaging survey has identified 80% of WN stars and 90% for the WC subclass. Allowing for incompleteness, NGC 7793 hosts ~105 WR stars for which N(WC)/N(WN)~0.5. From our spectroscopy of HII regions in NGC 7793, we revise the global Halpha star formation rate of Kennicutt et al. upward by 50% to 0.45 M_sun/yr. This allows us to obtain N(WR)/N(O)~0.018, which is somewhat lower than that resulting from the WR census by Schild et al. of another Sculptor group spiral NGC 300, whose global physical properties are similar to NGC 7793. Finally, we also report the fortuitous detection of a bright (m_V = 20.8 mag) background quasar Q2358-32 at z~2.02 resulting from CIV 1548-51 redshifted to the 4684 passband.Comment: 17 pages, 13 figures, accepted for MNRAS (detailed finding charts omitted)